FEBS Letters

Transcriptional regulation of the hepatocyte growth factor gene by pyrrolidine dithiocarbamate.

Publication Date: 2008 May 9 PMID: 18474243
Authors: Harrison, P. M. - Farzaneh, F.
Journal: FEBS Lett

Hepatocyte growth factor (HGF) mediates cancer cell invasion and metastasis. This study characterised the down-regulation of HGF expression by pyrrolidine dithiocarbamate (PDTC), which markedly reduced HGF mRNA expression and protein production in MRC-5 cells. Reporter gene studies revealed that PDTC inhibited HGF gene transcription and that the response element is located in the region -75 to +42bp flanking the transcription initiation site. Electrophoretic mobility shift assay identified three specific protein complexes binding in this region, which were abrogated by exposure of cells to PDTC. PDTC deserves further investigation as a novel therapeutic agent for HGF-driven cancers.

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Glutamate-induced glioma cell proliferation is prevented by functional expression of the glutamate transporter GLT-1.

Publication Date: 2008 May 9 PMID: 18474242
Authors: Vanhoutte, N. - Hermans, E.
Journal: FEBS Lett

A tetracycline-dependent inducible system was used to achieve controlled expression of the glutamate transporter 1 (GLT-1) in C6 glioma cells. Non-induced cells show modest glutamate uptake and, in the presence of l-cystine, these cells tend to release substantial amounts of glutamate. Overnight exposure to doxycycline increased d-[(3)H]-aspartate uptake, reaching similar capacity as observed in cultured astrocytes. Efficient clearance of exogenously applied glutamate was evidenced in these cells, even in the presence of l-cystine. The addition of glutamate (100muM) to the medium of non-induced cells significantly increased their proliferation rate, an effect that was blocked when the expression of GLT-1 was induced. This suggests that impaired glutamate uptake capacity in glioma cells indirectly contributes to their proliferation.

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The mammalian CHORD-containing protein melusin is a stress response protein interacting with Hsp90 and Sgt1.

Publication Date: 2008 May 9 PMID: 18474241
Authors: Sbroggio, M. - Ferretti, R. - Percivalle, E. - Gutkowska, M. - Zylicz, A. - Michowski, W. - Kuznicki, J. - Accornero, F. - Pacchioni, B. - Lanfranchi, G. - Hamm, J. - Turco, E. - Silengo, L. - Tarone, G. - Brancaccio, M.
Journal: FEBS Lett

Melusin is a mammalian muscle specific CHORD containing protein capable of activating signal transduction pathways leading to cardiomyocytes hypertrophy in response to mechanical stress. To define melusin function we searched for molecular partners possibly involved in melusin dependent signal transduction. Here we show that melusin and heat shock proteins are co-regulated. Moreover, melusin directly binds to Hsp90, a ubiquitous chaperone involved in regulating several signaling pathways. In addition, melusin interacts with Sgt1, an Hsp90 binding molecule. Melusin does not behave as an Hsp90 substrate but rather as a chaperone capable to protect citrate synthase from heat induced aggregation. These results describe melusin as a new component of the Hsp90 chaperone machinery. STRUCTURED SUMMARY:

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Metabolic and signaling properties of an Itpk gene family in Glycine max.

Publication Date: 2008 May 9 PMID: 18474240
Authors: Stiles, A. R. - Qian, X. - Shears, S. B. - Grabau, E. A.
Journal: FEBS Lett

We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P(3) 5/6-kinase activity, but a kinetic analysis raised questions about its biological significance. Instead, we provide evidence that one alternative biological role for soybean Itpks is to interconvert the Cl(-) channel inhibitor, Ins(3,4,5,6)P(4), and its metabolic precursor, Ins(1,3,4,5,6)P(5), within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P(3) to Ins(1,3,4,6)P(4) which was further phosphorylated to Ins(1,3,4,5,6)P(5) by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid-independent pathway of InsP(6) synthesis.

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p3 peptide, a truncated form of Abeta devoid of synaptotoxic effect, does not assemble into soluble oligomers.

Publication Date: 2008 May 9 PMID: 18474239
Authors: Dulin, F. - Leveille, F. - Ortega, J. B. - Mornon, J. P. - Buisson, A. - Callebaut, I. - Colloc'h, N.
Journal: FEBS Lett

In previously proposed models of Abeta soluble oligomers, the N-terminal domain Abeta(1-16), which is missing in p3 peptides, protects the hydrophobic core of the oligomers from the solvent. Without this N-terminal part, oligomers of p3 peptides would likely expose hydrophobic residues to water and would consequently be less stable. We thus suggest, based on theoretical and experimental results, that p3 peptides would have a low propensity to assemble into stable oligomers, evolving then directly to fibrillar aggregates. These properties may explain why p3 would be devoid of any impact on synaptic function and moreover, strengthen the hypothesis that Abeta oligomers are the principal synaptotoxic forms of Abeta peptides in Alzheimer disease.

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The nuclear envelope as an integrator of nuclear and cytoplasmic architecture.

Publication Date: 2008 May 9 PMID: 18474238
Authors: Crisp, M. - Burke, B.
Journal: FEBS Lett

Initially perceived as little more than a container for the genome, our view of the nuclear envelope (NE) and its role in defining global nuclear architecture has evolved significantly in recent years. The recognition that certain human diseases arise from defects in NE components has provided new insight into its structural and regulatory functions. In particular, NE defects associated with striated muscle disease have been shown to cause structural perturbations not just of the nucleus itself but also of the cytoplasm. It is now becoming increasingly apparent that these two compartments display co-dependent mechanical properties. The identification of cytoskeletal binding complexes that localize to the NE now reveals a molecular framework that can seamlessly integrate nuclear and cytoplasmic architecture.

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The involvement of caspase-11 in TPEN-induced apoptosis.

Publication Date: 2008 May 9 PMID: 18474237
Authors: Lee, J. M. - Kim, Y. J. - Ra, H. - Kang, S. J. - Han, S. - Koh, J. Y. - Kim, Y. H.
Journal: FEBS Lett

The depletion of intracellular zinc with N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) induces protein synthesis-dependent apoptosis. Here we examined the involvement of caspase induction in apoptosis. Among the examined caspases, only caspase-11 was increased by TPEN. Caspase-11 activity also increased, which resulted in caspase-3 activation. Cycloheximide or actinomycin D blocked caspase-11 induction, reduced caspase-11 and -3 activation, and attenuated TPEN-induced neuronal apoptosis. Blockade of caspase-11 by a chemical inhibitor or genetic deletion attenuated TPEN-induced apoptosis, indicating a critical role of caspase-11 in TPEN-induced apoptosis. Although mitochondria-mediated caspase-9/-3 activation also contributed to TPEN-induced apoptosis, caspase-11 is likely a key inducible apoptosis-inducing protein.

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The antioxidant properties of serum albumin.

Publication Date: 2008 May 9 PMID: 18474236
Authors: Roche, M. - Rondeau, P. - Singh, N. R. - Tarnus, E. - Bourdon, E.
Journal: FEBS Lett

Free radicals are a normal component of cellular oxygen metabolism in mammals. However, free radical-associated damage is an important factor in many pathological processes. Glycation and oxidative damage cause protein modifications, frequently observed in numerous diseases. Albumin represents a very abundant and important circulating antioxidant. This review brings together recent insights on albumin antioxidant properties. First, it focuses on the different activities of albumin concerning protein antioxidation. In particular, we describe the role of albumin in ligand binding and free radical-trapping activities. In addition, physiological and pathological situations that modify the antioxidant properties of albumin are reported.

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Anionic phospholipid-induced regulation of reactive oxygen species production by human cytochrome P450 2E1.

Publication Date: 2008 May 7 PMID: 18472009
Authors: Cho, E. I. - Yun, C. H. - Chae, H. Z. - Chae, H. J. - Ahn, T.
Journal: FEBS Lett

We suggest that the cytochrome P450 2E1 (CYP2E1)-induced formation of reactive oxygen species (ROS) can be regulated by anionic phospholipids and the presence of the N-terminal region of the enzyme. When the content of cardiolipin (CL) in membranes at the expense of phosphatidylcholine matrix was increased, the ROS produced by recombinant human CYP2E1 was decreased as a function of CL concentration. On the contrary, the N-terminally truncated CYP2E1 had a decreased effect on the lipid-induced reduction of ROS formation. These results suggest that specific phospholipids can regulate the function of CYP2E1 by interaction with the enzyme including the N-terminal region(s).

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Homotropic allosteric control in clostridial glutamate dehydrogenase: Different mechanisms for glutamate and NAD(+)?

Publication Date: 2008 May 7 PMID: 18472008
Authors: Hamza, M. A. - Engel, P. C.
Journal: FEBS Lett

Clostridial glutamate dehydrogenase mutants with the 5 Trp residues in turn replaced by Phe showed the importance of Trp 64 and 449 in cooperativity with glutamate at pH 9. These mutants are examined here for their behaviour with NAD(+) at pH 7.0 and 9.0. The wild-type enzyme displays negative NAD(+) cooperativity at both pH values. At pH 7.0 W243F gives Michaelis-Menten kinetics, and the same behaviour is shown by W243F and also W310F at pH 9.0, but not by W64F or W449F. W243 and W310 are apparently much more important than W64 and W449 for the coenzyme negative cooperativity, implying that different conformational transitions are involved in cooperativity with the coenzyme and with glutamate.

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A novel anticancer effect of butein: Inhibition of invasion through the ERK1/2 and NF-kappaB signaling pathways in bladder cancer cells.

Publication Date: 2008 May 7 PMID: 18472007
Authors: Zhang, L. - Chen, W. - Li, X.
Journal: FEBS Lett

There is increasing evidence that epithelial-mesenchymal transition (EMT) plays a critical role in cancer metastasis. Butein is a polyphenolic compound, which has been found to exhibit anti-proliferation effects on cancer cells. Here, we report that in addition to its function as an anti-proliferation agent, butein can inhibit migration and invasion through the ERK1/2 and NF-kappaB signaling pathways in human bladder cancer cells, and this inhibitory effect may be associated with reversal of EMT. These results were further confirmed by RNAi-mediated suppression of NF-kappaB, which partly reverses EMT and inhibits cell invasive ability in vitro. These results suggest a novel function of butein as an invasion inhibitor in bladder cancer.

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Maintenance of luminal NADPH in the endoplasmic reticulum promotes the survival of human neutrophil granulocytes.

Publication Date: 2008 May 7 PMID: 18472006
Authors: Kardon, T. - Senesi, S. - Marcolongo, P. - Legeza, B. - Banhegyi, G. - Mandl, J. - Fulceri, R. - Benedetti, A.
Journal: FEBS Lett

The present study demonstrates the expression of hexose-6-phosphate dehydrogenase and 11beta-hydroxysteroid dehydrogenase type 1 in human neutrophils, and the presence and activity of these enzymes in the microsomal fraction of the cells. Their concerted action together with the previously described glucose-6-phosphate transporter is responsible for cortisone-cortisol interconversion detected in human neutrophils. Furthermore, the results suggest that luminal NADPH generation by the cortisol dehydrogenase activity of 11beta-hydroxysteroid dehydrogenase type 1 prevents neutrophil apoptosis provoked by the inhibition of the glucose-6-phosphate transporter. In conclusion, the maintenance of the luminal NADPH pool is an important antiapoptotic factor in neutrophil granulocytes.

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Nuclear dynamics and cytoskeleton signaling.

Publication Date: 2008 May 7 PMID: 18472005
Authors: Kutay, U. - Stournaris, C.
Journal: FEBS Lett

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Tissue-specific expression of ALA synthase-1 and heme oxygenase-1 and their expression in livers of rats chronically exposed to ethanol.

Publication Date: 2008 May 7 PMID: 18472004
Authors: Zheng, J. - Tian, Q. - Hou, W. - Watts, J. A. - Schrum, L. W. - Bonkovsky, H. L.
Journal: FEBS Lett

5-Aminolevulinic acid synthase-1 (ALAS1) and heme oxygenase-1 (HO-1) are the rate-controlling enzymes for heme biosynthesis and degradation, respectively. Expression of these two genes showed tissue-specific expression pattern at both mRNA and protein levels in selected non-treated rat tissues. In the livers of rats receiving oral ethanol for 10 weeks, ALAS1 mRNA levels were increased by 65%, and the precursor and mature ALAS1 protein levels were increased by 1.8- and 2.3-fold, respectively, while no changes were observed in HO-1 mRNA and protein levels, compared with pair-fed controls. These results provide novel insights into the effects of chronic ethanol consumption on hepatic heme biosynthesis and porphyrias.

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Both upstream and downstream intergenic regions are critical for the mob as tumor suppressor gene activity in Drosophila.

Publication Date: 2008 May 7 PMID: 18472003
Authors: Yang, Y. - Gupta, V. - Ho, L. L. - Zhou, B. - Fan, Q. - Zhu, Z. - Zhang, W. - Lai, Z. C.
Journal: FEBS Lett

The Drosophila mats gene plays a critical role in growth control. Using molecular genetic approaches we investigated how mats is regulated in development. A 2236-bp genomic sequence that contains entire mats including upstream and downstream intergenic regions can rescue mats mutant phenotypes, indicating that regulatory elements necessary for proper mats expression are mostly retained. However, constructs without the upstream or downstream intergenic region failed to rescue mats mutants, demonstrating the functional importance of these sequences. Moreover, mats expression is reduced in mats(e17), a mats allele with over one-third of the downstream intergenic region deleted. Consistent with a model that the downstream intergenic region is critical for mats activity, this sequence contains evolutionarily conserved elements and has enhancer activities.

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Arginine methylation of hnRNP K enhances p53 transcriptional activity.

Publication Date: 2008 May 7 PMID: 18472002
Authors: Chen, Y. - Zhou, X. - Chen, X. - Hu, G.
Journal: FEBS Lett

Previous studies have illustrated that hnRNP K, which could be methylated at arginine residues, plays a key role in coordinating transcriptional responses to DNA damage as a cofactor for p53. In this study, we observed that hnRNP K was markedly arginine methylated in response to UV radiation. Furthermore, arginine methylation of hnRNP K enhanced its affinity with p53. Inhibition of methylation in hnRNP K attenuated the recruitment of p53 to p21 promoter, and reduced p53 transcriptional activity. These data suggested that arginine methylation of hnRNP K is a key element for p53 transcriptional activity.

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Endogenous reductions in N-methyl-d-aspartate receptor activity inhibit nitric oxide production in the anoxic freshwater turtle cortex.

Publication Date: 2008 May 6 PMID: 18466771
Authors: Pamenter, M. E. - Hogg, D. W. - Buck, L. T.
Journal: FEBS Lett

Increased nitric oxide (NO) production from hypoxic mammalian neurons increases cerebral blood flow (CBF) but also glutamatergic excitotoxicity and DNA fragmentation. Anoxia-tolerant freshwater turtles have evolved NO-independent mechanisms to increase CBF; however, the mechanism(s) of NO regulation are not understood. In turtle cortex, anoxia or NMDAR blockade depressed NO production by 27+/-3% and 41+/-5%, respectively. NMDAR antagonists also reduced the subsequent anoxic decrease in NO by 74+/-6%, suggesting the majority of the anoxic decrease is due to endogenous suppression of NMDAR activity. Prevention of NO-mediated damage during the transition to and from anoxia may be incidental to natural reductions of NMDAR activity in the anoxic turtle cortex.

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Characterization of a novel aphid prenyltransferase displaying dual geranyl/farnesyl diphosphate synthase activity.

Publication Date: 2008 May 5 PMID: 18466770
Authors: Vandermoten, S. - Charloteaux, B. - Santini, S. - Sen, S. E. - Beliveau, C. - Vandenbol, M. - Francis, F. - Brasseur, R. - Cusson, M. - Haubruge, E.
Journal: FEBS Lett

We report on the cDNA cloning and characterization of a novel short-chain isoprenyl diphosphate synthase from the aphid Myzus persicae. Of the three IPPS cDNAs we cloned, two yielded prenyltransferase activity following expression in Escherichia coli; these cDNAs encode identical proteins except for the presence, in one of them, of an N-terminal mitochondrial targeting peptide. Although the aphid enzyme was predicted to be a farnesyl diphosphate synthase by BLASTP analysis, rMpIPPS, when isopentenyl diphosphate and dimethylallyl diphosphate are supplied as substrates, typically generated geranyl diphosphate (C10) as its main product, along with significant quantities of farnesyl diphosphate (C15). Analysis of an MpIPPS homology model pointed to substitutions that could confer GPP/FPP synthase activity to the aphid enzyme.

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Acyclic retinoid inhibits functional interaction of transcription factors Kruppel-like factor 5 and retinoic acid receptor-alpha.

Publication Date: 2008 May 5 PMID: 18466769
Authors: Kada, N. - Suzuki, T. - Aizawa, K. - Munemasa, Y. - Matsumura, T. - Sawaki, D. - Nagai, R.
Journal: FEBS Lett

We show that transcription factor Kruppel-like factor 5 (KLF5), which is important in cardiovascular remodeling, interacts with retinoic acid receptor-alpha (RARalpha) to regulate downstream gene expression. Here, we investigated whether acyclic retinoid (ACR) regulates KLF5 and inhibits vascular remodeling. Co-immunoprecipitation and pull-down binding assay showed that ACR attenuates functional interaction of KLF5 and RARalpha. ACR affects KLF5 functions by regulating transactivation of platelet-derived growth factor A (PDGF-A) chain. ACR may be a new vascular therapy to target KLF5 in cardiovascular pathology.

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The hydrophobic segment of Arabidopsis thaliana cluster I diacylglycerol kinases is sufficient to target the proteins to cell membranes.

Publication Date: 2008 May 6 PMID: 18466768
Authors: Vaultier, M. N. - Cantrel, C. - Guerbette, F. - Boutte, Y. - Vergnolle, C. - Cicek, D. - Bolte, S. - Zachowski, A. - Ruelland, E.
Journal: FEBS Lett

Diacylglycerol kinases (DGKs) catalyze the phosphorylation of diacylglycerol into phosphatidic acid. To fulfill their role in many signalling processes, DGKs must be located at, or in, membranes. Most mammalian DGKs are cytosolic and are recruited to membranes upon stimulation, except for epsilon type DGKs that are permanently membrane-associated through a hydrophobic segment. Nothing is known about the mechanism(s) involved in the membrane localization of plant DGKs. By fusion to fluorescent proteins, we show that two DGKs from cluster I in Arabidopsis thaliana possess amino-terminal hydrophobic segments that are sufficient to address them to endoplasmic reticulum membranes.

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Domain organization of photosystem II in membranes of the cyanobacterium Synechocystis PCC6803 investigated by electron microscopy.

Publication Date: 2008 May 6 PMID: 18466767
Authors: Folea, I. M. - Zhang, P. - Aro, E. M. - Boekema, E. J.
Journal: FEBS Lett

The supramolecular organization of photosystem II (PSII) complexes in the photosynthetic membrane of the cyanobacterium Synechocystis 6803 was studied by electron microscopy. After mild detergent solubilization, crystalline PSII arrays were extracted in which dimeric PSII particles associate in multiple rows. Image processing of the arrays shows that the PSII dimers are tightly packed at distances of 12.2 and 16.7nm. The domains are considered to be an important type of association for preventing either spill-over energy from PSII towards photosystem I (PSI) or direct energy flow from phycobilisomes to PSI, because the latter can only be at periphery of the arrays.

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Rho GTPases in cancer cell biology.

Publication Date: 2008 May 5 PMID: 18460342
Authors: Vega, F. M. - Ridley, A. J.
Journal: FEBS Lett

Rho GTPases contribute to multiple cellular processes that could affect cancer progression, including cytoskeletal dynamics, cell cycle progression, transcriptional regulation, cell survival and vesicle trafficking. In vitro several Rho GTPases have oncogenic activity and/or can promote cancer cell invasion, and this correlates with increased expression and activity in a variety of cancers. Conversely, other family members appear to act as tumour suppressors and are deleted, mutated or downregulated in some cancers. Genetic models are starting to provide new information on how Rho GTPases affect cancer development and progression. Here, we discuss how Rho GTPases could contribute to different steps of cancer progression, including proliferation, survival, invasion and metastasis.

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FGF21 attenuates lipolysis in human adipocytes - A possible link to improved insulin sensitivity.

Publication Date: 2008 May 5 PMID: 18460341
Authors: Arner, P. - Pettersson, A. - Mitchell, P. J. - Dunbar, J. D. - Kharitonenkov, A. - Ryden, M.
Journal: FEBS Lett

Fibroblast growth factor 21 (FGF21) is active in murine adipocytes and has beneficial metabolic effects in animal models of type 2 diabetes mellitus. We assessed whether FGF21 influences lipolysis in human adipocytes and 3T3-L1 cells. FGF21 had no short-time effect (h) while a 3-day incubation with FGF21 attenuated hormone-stimulated lipolysis. FGF21 did not influence the mRNA expression of genes involved in regulating lipolysis, but significantly reduced the expression of the lipid droplet-associated phosphoprotein perilipin without affecting differentiation. Via reduced release of fatty acids into the circulation, the anti-lipolytic effect could be a mechanism through which FGF21 promotes insulin sensitivity in man.

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High molecular weight adiponectin activates AMPK and suppresses cytokine-induced NF-kappaB activation in vascular endothelial cells.

Publication Date: 2008 May 1 PMID: 18455514
Authors: Hattori, Y. - Nakano, Y. - Hattori, S. - Tomizawa, A. - Inukai, K. - Kasai, K.
Journal: FEBS Lett

Various isoforms of adiponectin circulate in the plasma. We purified high molecular weight (HMW) adiponectin from human plasma. HMW adiponectin was observed to activate AMP-activated protein kinase (AMPK), thereby increasing the phosphorylation of eNOS and NO production in endothelial cells. On the other hand, cells preincubated with HMW adiponectin had reduced TNFalpha-induced NF-kappaB activation. HMW adiponectin by itself was found to modestly activate NF-kappaB, which was significantly enhanced by inhibition of AMPK/eNOS activation. Thus, HMW adiponectin might have dual action, both pro and anti-inflammatory. An initial period of NF-kappaB activation by HMW adiponectin might be proinflammatory, but it could be counteracted by activation of AMPK/eNOS, which lead to a potential reduction in a second activation of NF-kappaB against inflammatory stimuli.

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Directional sensing during chemotaxis.

Publication Date: 2008 Apr 29 PMID: 18452713
Authors: Janetopoulos, C. - Firtel, R. A.
Journal: FEBS Lett

Cells have the innate ability to sense and move towards a variety of chemoattractants. We investigate the pathways by which cells sense and respond to chemoattractant gradients. We focus on the model system Dictyostelium and compare our understanding of chemotaxis in this system with recent advances made using neutrophils and other mammalian cell types, which share many molecular components and signaling pathways with Dictyostelium. This review also examines models that have been proposed to explain how cells are able to respond to small differences in ligand concentrations between the anterior leading edge and posterior of the cell. In addition, we highlight the overlapping functions of many signaling components in diverse processes beyond chemotaxis, including random cell motility and cell division.

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Investigating the nucleic acid interactions and antimicrobial mechanism of buforin II.

Publication Date: 2008 Apr 28 PMID: 18448075
Authors: Uyterhoeven, E. T. - Butler, C. H. - Ko, D. - Elmore, D. E.
Journal: FEBS Lett

Buforin II (BF2) is an antimicrobial peptide that is hypothesized to kill bacteria by entering cells and binding nucleic acids. To further investigate this proposed mechanism, we used computer modeling and experimental measurements to consider the interactions between BF2 and DNA. Computational and experimental results imply that the peptide forms specific interactions with DNA. Moreover, we observe a general correlation between DNA affinity and antimicrobial activity for a series of BF2 variants. Thus, our results support the proposed mechanism for BF2 and provide a useful approach for evaluating the nucleic acid interactions of other antimicrobial peptides.

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Chromatin remodelling and actin organisation.

Publication Date: 2008 Apr 28 PMID: 18442483
Authors: Farrants, A. K.
Journal: FEBS Lett

Chromatin remodelling is a prerequisite for nuclear processes, and cells have several different ways of remodelling the chromatin structure. The ATP-dependent chromatin remodelling complexes are large multiprotein complexes that use ATP to change DNA-histone contacts. These complexes are classified into 4 sub-families depending on the central ATPase. The switch mating type/sucrose non-fermenting (SWI/SNF) complexes are mainly involved in transcriptional regulation, and this means that they are involved in many processes, such as the formation of actin filaments in the cytoplasm. SWI/SNF complexes are involved in the regulation of genes expressing cell adhesion proteins and extracellular matrix proteins. Actin is also present in the nucleus, affecting transcription, RNA processing and export. In addition, actin and actin-related proteins are subunits of SWI/SNF complexes and the INO80-containing complexes, another subfamily of ATP-dependent chromatin remodelling complexes. Not all functions of the actin and actin-related proteins in the complexes are yet clear: it is known that they play important roles in maintaining the stability of the proteins, possibly by bridging subunits and recruiting the complexes to chromatin.

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A Solanum tuberosum inositol phosphate kinase (StITPK1) displaying inositol phosphate-inositol phosphate and inositol phosphate-ADP phosphotransferase activities.

Publication Date: 2008 Apr 28 PMID: 18442482
Authors: Caddick, S. E. - Harrison, C. J. - Stavridou, I. - Mitchell, J. L. - Hemmings, A. M. - Brearley, C. A.
Journal: FEBS Lett

We describe a multifunctional inositol polyphosphate kinase/phosphotransferase from Solanum tuberosum, StITPKalpha (GenBank accession number: EF362784), hereafter called StITPK1. StITPK1 displays inositol 3,4,5,6-tetrakisphosphate 1-kinase activity: K(m)=27muM, and V(max)=19nmolmin(-1)mg(-1). The enzyme displays inositol 1,3,4,5,6-pentakisphosphate 1-phosphatase activity in the absence of a nucleotide acceptor and inositol 1,3,4,5,6-pentakisphosphate-ADP phosphotransferase activity in the presence of physiological concentrations of ADP. Additionally, StITPK1 shows inositol phosphate-inositol phosphate phosphotransferase activity. Homology modelling provides a structural rationale of the catalytic abilities of StITPK1. Inter-substrate transfer of phosphate groups between inositol phosphates is an evolutionarily conserved function of enzymes of this class.

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Reduced response to adiponectin and lower abundance of adiponectin receptor proteins in type 2 diabetic monocytes.

Publication Date: 2008 Apr 28 PMID: 18442481
Authors: Weigert, J. - Neumeier, M. - Wanninger, J. - Wurm, S. - Kopp, A. - Schober, F. - Filarsky, M. - Schaffler, A. - Zeitoun, M. - Aslanidis, C. - Buechler, C.
Journal: FEBS Lett

The abundance of the adiponectin receptors, AdipoR1 and AdipoR2, and the effects of the antidiabetic adipokine adiponectin in monocytes of normal-weight and overweight controls and type 2 diabetic patients (T2D) were analyzed. AdipoR1 and AdipoR2 mRNAs were increased in monocytes of obese controls and T2D patients when compared to normal-weight controls, and AdipoR1 mRNA positively correlated to AdipoR2 mRNA, the waist to hip ratio and systemic adiponectin. However, AdipoR1 and AdipoR2 proteins were lower in monocytes of T2D compared to normal-weight donors. Induction of IL-6 and IL-8 by adiponectin, an effect involving p38 MAPK, was also reduced in T2D monocytes.

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Nuclear functions in space and time: Gene expression in a dynamic, constrained environment.

Publication Date: 2008 Apr 28 PMID: 18442480
Authors: Trinkle-Mulcahy, L. - Lamond, A. I.
Journal: FEBS Lett

All eukaryotic cells enclose their genome within a dedicated, membrane-bound organelle termed the nucleus, which functions to partition gene transcription from sites of protein translation in the cytoplasm. Despite a great deal of research effort, basic questions about chromosome structure and gene expression mechanisms remain to be answered, including the relationship between the spatial organization of the genome and the transcription machinery. Powerful in vivo approaches are allowing researchers to test established in vitro concepts within the dynamic cellular environment, while genome-wide screens have enabled rapid high throughput analyses of both structural and functional parameters. In several cases, as highlighted here, this has turned up surprising results and has forced a re-evaluation of models for nuclear structure and gene regulation.

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Dissociation of superoxide production by mitochondrial complex I from NAD(P)H redox state.

Publication Date: 2008 Apr 28 PMID: 18442479
Authors: Lambert, A. J. - Buckingham, J. A. - Brand, M. D.
Journal: FEBS Lett

The relationship between the rate of superoxide production by complex I and NAD(P)H redox state was investigated in rat skeletal muscle mitochondria. A high rate of superoxide production was observed during succinate oxidation; the rate during pyruvate oxidation was over fourfold lower. However, the NAD(P)H pool was significantly less reduced during succinate oxidation than during pyruvate oxidation. We conclude that there is no unique relationship between superoxide production by complex I and the reduction state of the NAD(P)H pool. Our data suggest that less than 10% of the superoxide originates from the flavin site during reverse electron transport from succinate.

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On the Rho'd: The regulation of membrane protrusions by Rho-GTPases.

Publication Date: 2008 Apr 28 PMID: 18442478
Authors: Ladwein, M. - Rottner, K.
Journal: FEBS Lett

Cell migration entails the formation of cellular protrusions such as lamellipodia or filopodia, the growth of which is powered by the polymerisation of actin filaments abutting the plasma membrane. Specific Rho-GTPase subfamilies are able to drive different types of protrusions. However, significant crosstalk between Rho-family members and the interplay of distinct Rho-effectors regulating or modulating actin reorganization in protrusions complicate the picture of how precisely they are initiated and maintained. Here, we briefly sketch our current knowledge on structure and dynamics of different protrusions as well as their regulation by Rho-GTPases. We also comment on topical, unresolved controversies in the field, with special emphasis on the interrelation of different protrusion types, and on the composition of the nanomachineries driving them.

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Down-regulation of Notch-dependent transcription by Akt in vitro.

Publication Date: 2008 Apr 25 PMID: 18440314
Authors: Song, J. - Park, S. - Kim, M. - Shin, I.
Journal: FEBS Lett

The effect of Akt on Notch intracellular domain (NICD)-mediated transcription was investigated. Transfection experiments revealed that constitutively active Akt down-regulates NICD-dependent transcription. Kinase inactive dominant negative Akt did not affect NICD transcriptional activity, indicating that Akt kinase activity is responsible for the down-regulation. Studies using histone deacetylase (HDAC) and silencing mediator of retinoid and thyroid hormone receptor (SMRT) revealed that modulation of NICD transcriptional activity is not mediated by an HDAC-dependent mechanism or recruitment of the co-repressor SMRT. Akt inhibited proper nuclear localization of NICD, and phosphorylated NICD both in vitro and caused its hyperphosphorylation in vivo. These results may suggest possible regulation of NICD transcriptional activity by Akt-mediated phosphorylation and subsequent inhibition of proper nuclear localization of NICD.

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Chromosome damage in mitosis induces BubR1 activation and prometaphase arrest.

Publication Date: 2008 Apr 25 PMID: 18440313
Authors: Choi, E. - Lee, H.
Journal: FEBS Lett

The effect of double-strand DNA breaks (DSBs) on the spindle assembly checkpoint (SAC) has important implications with respect to the relationship between SAC function and chromosome instability of cancer cells. Here, we demonstrate that induction of DSBs in mitosis results in prolonged hyper-phosphorylation of the SAC protein BubR1 and association of BubR1 with kinetochores in mammalian cells. Combining single cell time-lapse microscopy with immunofluorescence, flow cytometry, and Western blot analysis in synchronized cells, we provide evidence that DSBs activate BubR1, leading to prometaphase arrest. Accordingly, elimination of BubR1 expression by siRNA resulted in the abrogation of mitotic delay in response to chromosome damage. These results suggest that BubR1 links DNA damage to kinetochore-associated SAC function.

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Protein kinase C protects from DNA damage-induced necrotic cell death by inhibiting poly(ADP-ribose) polymerase-1.

Publication Date: 2008 Apr 24 PMID: 18439913
Authors: Hegedus, C. - Lakatos, P. - Olah, G. - Toth, B. I. - Gergely, S. - Szabo, E. - Biro, T. - Szabo, C. - Virag, L.
Journal: FEBS Lett

The goal of the current study, conducted in freshly isolated thymocytes was (1) to investigate the possibility that the activation of poly(ADP-ribose) polymerase-1 (PARP-1) in an intact cell can be regulated by protein kinase C (PKC) mediated phosphorylation and (2) to examine the consequence of this regulatory mechanism in the context of cell death induced by the genotoxic agent. In cells stimulated by the PKC activating phorbol esters, DNA breakage was unaffected, PARP-1 was phosphorylated, 1-methyl-3-nitro-1-nitrosoguanidine-induced PARP activation and cell necrosis were suppressed, with all these effects attenuated by the PKC inhibitors GF109203X or Go6976. Inhibition of cellular PARP activity by PKC-mediated phosphorylation may provide a plausible mechanism for the previously observed cytoprotective effects of PKC activators.

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Increased abundance of cytoplasmic and nuclear caveolin 1 in human diploid fibroblasts in H(2)O(2)-induced premature senescence and interplay with p38alpha(MAPK).

Publication Date: 2008 Apr 23 PMID: 18439424
Authors: Chretien, A. - Piront, N. - Delaive, E. - Demazy, C. - Ninane, N. - Toussaint, O.
Journal: FEBS Lett

Treatment of IMR-90 human diploid fibroblasts with a sublethal concentration of H(2)O(2) induces premature senescence. We investigated the protein abundance, subcellular localization and involvement of caveolin 1 in premature senescence. Caveolin 1 is a scaffolding protein able to concentrate and organize signaling molecules within the caveolae membrane domains. We report the first evidence of increased nuclear and cytoplasmic localization of caveolin 1 during establishment of H(2)O(2)-induced premature senescence. Moreover, we demonstrate that phosphorylation of caveolin 1 during treatment with H(2)O(2) is dependent on p38alpha mitogen-activated protein kinase.

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Evidence for multiple peroxisome proliferator-activated receptor gamma transcripts in bone: Fine-tuning by hormonal regulation and mRNA stability.

Publication Date: 2008 May 14 PMID: 18435931
Authors: Bruedigam, C. - Koedam, M. - Chiba, H. - Eijken, M. - van Leeuwen, J. P.
Journal: FEBS Lett

The expression, regulation and functional significance of multiple peroxisome proliferator-activated receptor gamma transcript variants in bone were studied. PPARG transcripts giving rise to PPARg-1 protein were expressed in human osteoblasts, whereas PPARG-2 transcript and protein remained virtually absent. PPARG expression underwent homologous regulation, was upregulated during differentiation and directly induced by the osteogenic hormone dexamethasone, suggesting a role for PPARg-1 in osteogenesis. Differences between the stabilities of PPARG-1, -3 and -4 were observed. We hypothesize that cell-specific expression patterns of multiple PPARG transcript variants encoding for the same protein but differing in mRNA stabilities enable a fine-tuning of PPARG action, which eventually supports a well-adjusted signal transduction between the cell and its environment.

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Spectroscopic and photochemical analysis of proteorhodopsin variants from the surface of the Arctic Ocean.

Publication Date: 2008 Apr 22 PMID: 18435930
Authors: Jung, J. Y. - Choi, A. R. - Lee, Y. K. - Lee, H. K. - Jung, K. H.
Journal: FEBS Lett

Proteorhodopsin (PR), a retinal-containing seven transmembrane helix protein, functions as a light-driven proton pump. Using PCR, we isolated 18 PR variants originating from the surface of the Arctic Ocean. Their absorption maxima were between 517 and 546nm at pH 7. One of the isolates turned out to be identical to GPR (green light-absorbing proteorhodopsin) from Monterey Bay. Interestingly, 10 isolates had replaced a tyrosine in the retinal-binding site (Tyr200 in GPR) with Asn. They showed a slower photocycle, more blue-shifted absorption maxima at pH 10, and relatively larger DeltaH and DeltaS of activation of the transition between the O intermediate and the ground state compared to GPR.

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A comparative metabolomic study of NHR-49 in Caenorhabditis elegans and PPAR-alpha in the mouse.

Publication Date: 2008 Apr 22 PMID: 18435929
Authors: Atherton, H. J. - Jones, O. A. - Malik, S. - Miska, E. A. - Griffin, J. L.
Journal: FEBS Lett

Proton Nuclear Magnetic Resonance spectroscopy and Gas Chromatography Mass Spectrometry based metabolomics has been used in conjunction with multivariate statistics to examine the metabolic changes in Caenorhabditis elegans following the deletion of nuclear hormone receptor-49 (nhr-49). Deletion of the receptor produced profound changes in fatty acid metabolism, in particular an increase in the ratio of unsaturated to saturated fatty acids, a decrease in the concentration of glucose and increases in lactate and alanine. Given the proposed functional similarity between nhr-49 and the mammalian peroxisome proliferator-activated receptors (PPARs) these changes were compared with the metabolome of the PPAR-alpha null mouse. The metabolomic approach demonstrated a number of similarities including the regulation of lipid synthesis, beta-oxidation of fatty acids and changes in glycolysis/gluconeogenesis.

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Crystal structure of the Ca(2+)-form and Ca(2+)-binding kinetics of metastasis-associated protein, S100A4.

Publication Date: 2008 Apr 22 PMID: 18435928
Authors: Gingras, A. R. - Basran, J. - Prescott, A. - Kriajevska, M. - Bagshaw, C. R. - Barsukov, I. L.
Journal: FEBS Lett

S100A4 takes part in control of tumour cell migration and contributes to metastatic spread in in vivo models. In the active dimeric Ca(2+)-bound state it interacts with multiple intracellular targets. Conversely, oligomeric forms of S100A4 are linked with the extracellular function of this protein. We report the 1.5A X-ray crystal structure of Ca(2+)-bound S100A4 and use it to identify the residues involved in target recognition and to derive a model of the oligomeric state. We applied stopped-flow analysis of tyrosine fluorescence to derive kinetics of S100A4 activation by Ca(2+) (k(on)=3.5muM(-1)s(-1), k(off)=20s(-1)).

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Alpha-lipoic acid induces apoptosis in hepatoma cells via the PTEN/Akt pathway.

Publication Date: 2008 Apr 22 PMID: 18435927
Authors: Shi, D. Y. - Liu, H. L. - Stern, J. S. - Yu, P. Z. - Liu, S. L.
Journal: FEBS Lett

We report here that alpha-lipoic acid (alpha-LA), a naturally-occurring antioxidant, scavenges reactive oxygen species (ROS) followed by an increase in apoptosis of human hepatoma cells. Apoptosis induced by alpha-LA was dependent upon the activation of the caspase cascade and the mitochondrial death pathway. alpha-LA induced increases in caspase-9 and caspase-3 but had no significant effect on caspase-8 activity. Apoptosis induced by alpha-LA was found to be mediated through the tensin homologue deleted on chromosome 10 (PTEN)/Akt pathway. Prior to cell apoptosis, PTEN was activated and its downstream target Akt was inhibited. Our findings indicate that increasing ROS scavenging could be a therapeutic strategy to treat cancer.

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Centromeres: Old tales and new tools.

Publication Date: 2008 Apr 22 PMID: 18435926
Authors: Vagnarelli, P. - Ribeiro, S. A. - Earnshaw, W. C.
Journal: FEBS Lett

The centromere is a specialised region of the eukaryotic chromosome that directs the equal segregation of sister chromatids into two daughter cells during mitosis. In mitosis, the kinetochores mediate (1) microtubule capture and chromosome alignment at a metaphase plate; (2) the correction of improper microtubule attachments; (3) the maintenance of an active checkpoint until bi-orientation is achieved by the whole complement of chromosomes; (4) the establishment of tension within the centromere which, in turn, contributes to silencing of the spindle checkpoint and triggers the onset of anaphase. In this review, we will analyse how centromeres are organised with respect to chromatin types and arrangements.

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Effect of 1-methyladenine on double-helical DNA structures.

Publication Date: 2008 May 14 PMID: 18435925
Authors: Yang, H. - Zhan, Y. - Fenn, D. - Chi, L. M. - Lam, S. L.
Journal: FEBS Lett

Methylation at the N1 site of adenine leads to the formation of cytotoxic 1-methyladenine (m1A). Since the N1 site of adenine is involved in the hydrogen bonding of T.A and A.T Watson-Crick base pairs, it is expected that the pairing interactions will be disrupted upon 1-methylation. In this study, high-resolution NMR investigations were performed to determine the effect of m1A on double-helical DNA structures. Interestingly, instead of disrupting hydrogen bonding, we found that 1-methylation altered the T.A Watson-Crick base pair to T(anti).m1A(syn) Hoogsteen base pair, providing insights into the observed differences in AlkB-repair efficiency between dsDNA and ssDNA.

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Binding of recombinant human coagulation factor VIII to lipid nanotubes.

Publication Date: 2008 Apr 22 PMID: 18435924
Authors: Parmenter, C. D. - Stoilova-McPhie, S.
Journal: FEBS Lett

Cryo-electron microscopy has the power to visualise lipid membranes at the closest to in vivo conditions. The structure of the lipid bilayer can be well resolved and the interactions between lipid-protein and protein-protein molecules followed at the molecular level. We undertook an extended Cryo-electron microscopy study to follow the factor VIII binding to phosphatidylserine containing lipid nanotubes at different lipid composition. Obtaining well ordered tubes is required to define the factor VIII membrane-bound structure. The observed alterations in the arrangement of the protein molecules are indicative for the flexibility of the membrane-bound factor VIII. Understanding the significance of these conformational changes is essential to comprehend the function of factor VIII in coagulation and as a drug for Hemophilia A.

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The CTD role in cotranscriptional RNA processing and surveillance.

Publication Date: 2008 Apr 22 PMID: 18435923
Authors: de Almeida, S. F. - Carmo-Fonseca, M.
Journal: FEBS Lett

In higher eukaryotes, the production of mature messenger RNA that exits the nucleus to be translated into protein requires precise and extensive processing of the nascent transcript. The processing steps include 5'-end capping, splicing, and 3'-end formation. Pre-mRNA processing is coupled to transcription by mechanisms that are not well understood but involve the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II. This review focuses on recent findings that provide novel insight into the role of the CTD in promoting RNA processing and surveillance.

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Dipyrithione inhibits lipopolysaccharide-induced iNOS and COX-2 up-regulation in macrophages and protects against endotoxic shock in mice.

Publication Date: 2008 Apr 22 PMID: 18435922
Authors: Liu, Z. - Fan, Y. - Wang, Y. - Han, C. - Pan, Y. - Huang, H. - Ye, Y. - Luo, L. - Yin, Z.
Journal: FEBS Lett

Dipyrithione (PTS2) possesses anti-bacterial and anti-fungal activity. In the present study, we found that PTS2 dose-dependently inhibited the LPS-induced up-regulation of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein level in RAW264.7 cells. RT-PCR experiments showed that PTS2 suppressed LPS-induced iNOS but not COX-2 expression at the mRNA level. As expected, PTS2 prevented NO secretion in RAW264.7 cells. Furthermore, PTS2 administration significantly decreased LPS-induced mortality in mice. Mechanistically, PTS2 decreased expression and phosphorylation of STAT1, but did not interfere with the MAPK and NF-kappaB pathways. In conclusion, PTS2 protects mice against endotoxic shock and inhibits LPS-induced production of pro-inflammatory mediators, suggesting that PTS2 could play an anti-inflammatory role in response to LPS.

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Chromatin organization in relation to the nuclear periphery.

Publication Date: 2008 Apr 22 PMID: 18435921
Authors: Kalverda, B. - Roling, M. D. - Fornerod, M.
Journal: FEBS Lett

In the limited space of the nucleus, chromatin is organized in a dynamic and non-random manner. Three ways of chromatin organization are compaction, formation of loops and localization within the nucleus. To study chromatin localization it is most convenient to use the nuclear envelope as a fixed viewpoint. Peripheral chromatin has both been described as silent chromatin, interacting with the nuclear lamina, and active chromatin, interacting with nuclear pore proteins. Current data indicate that the nuclear envelope is a reader as well as a writer of chromatin state, and that its influence is not limited to the nuclear periphery.

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Differential hTERT mRNA processing between young and older glioma patients.

Publication Date: 2008 Apr 22 PMID: 18435920
Authors: Shervington, A. - Patel, R.
Journal: FEBS Lett

The amplification of hTERT was detected in glioma tissues, although telomerase activity was not always found within these specimens. The aim of this study was to correlate the level of hTERT transcription with telomerase activity in two glioma age groups. hTERT was significantly transcribed at similar copy numbers in both age groups. However, these mRNAs translated to telomerase in 100% of the young compared to only 25% of the older patients. While hTERT transcription correlated directly to telomerase protein level and activity, as well as longer telomeres in the young group, such correlations were missing in the older group.

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The Arabidopsis thaliana aquaglyceroporin AtNIP7;1 is a pathway for arsenite uptake.

Publication Date: 2008 May 14 PMID: 18435919
Authors: Isayenkov, S. V. - Maathuis, F. J.
Journal: FEBS Lett

We studied the effect of loss of function in the NIP subfamily II in Arabidopsis thaliana to assess their potential role(s) in arsenite (AsIII) uptake. Loss of function in AtNIP7;1 led to increased plant tolerance to AsIII and reduced total As in planta. AtNIP7;1 expression in various yeast backgrounds increased AsIII sensitivity. In the acr3Delta yeast genotype, AtNIP7;1 caused a moderate increase in AsV tolerance. Short-term As uptake in fsp1Delta expressing AtNIP7;1 was significantly larger than that in the empty vector control. The data suggest that AtNIP7;1 can mediate AsIII transport and contributes to AsIII uptake in plants.

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Aggregation of proteins having Golgi apparatus sorting determinant induces large globular structures derived from the endoplasmic reticulum in plant seed cells.

Publication Date: 2008 May 14 PMID: 18423406
Authors: Maruyama, N. - Okuda, E. - Tatsuhara, M. - Utsumi, S.
Journal: FEBS Lett

Endoplasmic reticulum (ER)-derived compartments are found in many plant species. Although it has been assumed that aggregation induces formation of the ER-derived compartments in plant seed cells, the effect of aggregation on the trafficking from the ER to the Golgi has not yet been elucidated. In this study, we used an aggregated type of red fluorescent protein (DsRED) to investigate the effect of aggregation on sorting in seed cells. DsRED fused to the Golgi sorting determinant was found mainly in large globular structures derived from the ER where ER-resident proteins were excluded. These results indicate that aggregation of the Golgi protein blocks transport from the ER to the Golgi.

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ROCK and PRK-2 mediate the inhibitory effect of Y-27632 on polyglutamine aggregation.

Publication Date: 2008 Apr 16 PMID: 18423405
Authors: Shao, J. - Welch, W. J. - Diamond, M. I.
Journal: FEBS Lett

Polyglutamine expansion in huntingtin (Htt) and the androgen receptor (AR) causes untreatable neurodegenerative diseases. Y-27632, a therapeutic lead, reduces Htt and AR aggregation in cultured cells, and Htt-induced neurodegeneration in Drosophila. Y-27632 inhibits both Rho-associated kinases ROCK and PRK-2, making its precise intracellular target uncertain. Over-expression of either kinase increases Htt and AR aggregation. Three ROCK inhibitors (Y-27632, HA-1077, and H-1152P), and a specific ROCK inhibitory peptide reduce polyglutamine protein aggregation, as does knockdown of ROCK or PRK-2 by RNAi. RNAi also indicates that each kinase is required for the inhibitory effects of Y-27632 to manifest fully. These two actin regulatory kinases are thus involved in polyglutamine aggregation, and their simultaneous inhibition may be an important therapeutic goal.

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Nuclear actin dynamics - From form to function.

Publication Date: 2008 Apr 16 PMID: 18423404
Authors: Vartiainen, M. K.
Journal: FEBS Lett

Cell biological functions of actin have recently expanded from cytoplasm to nucleus, with actin implicated in such diverse processes as gene expression, transcription factor regulation and intranuclear motility. Actin in the nucleus seems to behave differently than in the cytoplasm, raising new questions regarding the molecular mechanisms by which actin functions in cells. In this review, I will discuss dynamic properties of nuclear actin that are related to its polymerization cycle and nucleocytoplasmic shuttling. By comparing the behaviour of nuclear and cytoplasmic actin and their regulators, I try to dissect the underlying differences of these equally important cellular actin pools.

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Adiponectin promotes endothelial progenitor cell number and function.

Publication Date: 2008 May 14 PMID: 18423403
Authors: Shibata, R. - Skurk, C. - Ouchi, N. - Galasso, G. - Kondo, K. - Ohashi, T. - Shimano, M. - Kihara, S. - Murohara, T. - Walsh, K.
Journal: FEBS Lett

Obesity-linked diseases are associated with suppressed endothelial progenitor cell (EPC) function. Adiponectin is an adipose-derived protein that is downregulated in obese and diabetic subjects. Here, we investigated the effects of adiponectin on EPCs. EPC levels did not increase in adiponectin deficient (APN-KO) in response to hindlimb ischemia. Adenovirus-mediated delivery of adiponectin increased EPC levels in both WT and APN-KO mice. Incubation of human peripheral blood mononuclear cells with adiponectin led to an increase of the number of EPCs. Adiponectin induced EPC differentiation into network structures and served as a chemoattractant in EPC migration assays. These data suggest that hypoadiponectinemia may contribute to the depression of EPC levels that are observed in patients with obesity-related cardiovascular disorders.

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Proteins in the insulin-secreting cell line MIN6 bind the imidazoline compound BL11282.

Publication Date: 2008 May 14 PMID: 18420036
Authors: Shafqat, J. - Ishrat, M. - Jagerbrink, T. - Sillard, R. - Maeorg, U. - Efendic, S. - Berggren, P. O. - Zaitsev, S. V. - Jornvall, H.
Journal: FEBS Lett

The imidazoline BL11282 stimulates insulin release and alters islet proteomes. Subcellular fractions of MIN6 cells showed that the membrane fraction exhibited binding to BL11282 on a Biacore chip and to BL11282-labelled magnetic beads. Bound material extracted from the beads showed a approximately 50kDa differential band upon SDS-PAGE and a weaker 100kDa band. The former was sensitive to competitive removal by preincubation of the fraction with BL11282, then highlighting the approximately 100kDa band. Masspectrometric analysis revealed the approximately 50kDa band to be EF1A and the approximately 100kDa band to be glucose regulated P94, both of interest in insulin synthesis and secretion.

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Glucuronic acid can extend O-linked core 1 glycans, but it contributes only weakly to the negative surface charge of Drosophila melanogaster Schneider-2 cells.

Publication Date: 2008 May 14 PMID: 18417079
Authors: Breloy, I. - Schwientek, T. - Lehr, S. - Hanisch, F. G.
Journal: FEBS Lett

Previous studies of the mucin-type O-glycome of the fruit fly Drosophila melanogaster have revealed a restricted pattern of neutral core-type glycans corresponding to the Tn-(GalNAcalpha) and the T-antigen (Galbeta1-3GalNAcalpha). In particular, no extension of the core 1 glycan with acidic sugars, like sialic acid, was detected. Here we report on the identification of an acidic O-linked trisaccharide expressed on secreted endogenous and recombinant glycoproteins of the embryonal hemocyte-like Drosophila Schneider-2 (S2) cell line. The glycan is composed of glucuronic acid, galactose and N-acetylgalactosamine and its structure was determined as GlcA1-3Gal1-3GalNAc. The O-linked trisaccharide resembles the peripheral structures of acidic D. melanogaster glycosphingolipids. Glucuronic acid may substitute for sialic acid in this organism, however its expression on the S2 cell surface may only marginally contribute to the negative surface charge as revealed by free-flow cell electrophoresis prior to and after beta-glucuronidase treatment of the cells.

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The ER-associated degradation component Der1p and its homolog Dfm1p are contained in complexes with distinct cofactors of the ATPase Cdc48p.

Publication Date: 2008 May 14 PMID: 18407841
Authors: Goder, V. - Carvalho, P. - Rapoport, T. A.
Journal: FEBS Lett

Misfolded proteins in the endoplasmic reticulum (ER) are often degraded in the cytosol by a process called ER-associated protein degradation (ERAD). During ERAD in S. cerevisiae, the ATPase Cdc48p associates with Der1p, a putative component of a retro-translocation channel. Cdc48p also binds a homolog of Der1p, Dfm1p, that has no known function in ERAD. Here, we show that Der1p and Dfm1p are contained in distinct complexes. While the complexes share several ERAD components, only the Dfm1p complex contains the Cdc48p cofactors Ubx1p and Ubx7p, while the Der1p complex is enriched in Ufd1p. These data suggest distinct functions for the Der1p and Dfm1p complexes. STRUCTURED SUMMARY:

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Inactivation of epoxide hydrolase by catalysis-induced formation of isoaspartate.

Publication Date: 2008 May 14 PMID: 18406355
Authors: van Loo, B. - Permentier, H. P. - Kingma, J. - Baldascini, H. - Janssen, D. B.
Journal: FEBS Lett

Epoxide hydrolases catalyze hydrolytic epoxide ring-opening, most often via formation of a covalent hydroxyalkyl-enzyme intermediate. A mutant of Agrobacterium radiobacter epoxide hydrolase, in which the phenylalanine residue that flanks the invariant catalytic aspartate nucleophile is replaced by a threonine, exhibited inactivation during conversion when the (R)-enantiomer of para-nitrostyrene epoxide was used as substrate. HPLC analysis of tryptic fragments of the epoxide hydrolase, followed by MALDI-TOF and TOF/TOF analysis, indicated that inactivation was due to conversion of the nucleophilic aspartate into isoaspartate, which represents a novel mechanism of catalysis-induced autoinactivation. Inactivation occurred at a lower rate with the (S)-enantiomer of para-nitrostyrene epoxide, indicating that it is related to the structure of the covalent hydroxyalkyl-enzyme intermediate.

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Monitoring fibril formation of the N-terminal domain of PABPN1 carrying an alanine repeat by tryptophan fluorescence and real-time NMR.

Publication Date: 2008 May 14 PMID: 18406354
Authors: Rohrberg, J. - Sachs, R. - Lodderstedt, G. - Sackewitz, M. - Balbach, J. - Schwarz, E.
Journal: FEBS Lett

Intranuclear fibrils due to poly-alanine expansions in the N-terminal domain of the poly(A) binding protein PABPN1 correlate with the disease oculopharyngeal muscular dystrophy (OPMD). For monitoring fibril formation by fluorescence and real-time NMR spectroscopy, tryptophans were introduced either into the middle or C-terminal of the poly-alanine segment. The kinetics of fibril formation which were monitored by fluorescence spectroscopy were matched by real-time NMR kinetics. Our results show that fibril formation is concomitant with the burial of the tryptophans in the fibrillar core. Since no soluble pre-fibrillar intermediate(s) was detected, fibril formation of this domain may be regarded as a two state conversion from an unfolded soluble into folded insoluble species.

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Downregulation of CCND1 and CDK6 by miR-34a induces cell cycle arrest.

Publication Date: 2008 Apr 30 PMID: 18406353
Authors: Sun, F. - Fu, H. - Liu, Q. - Tie, Y. - Zhu, J. - Xing, R. - Sun, Z. - Zheng, X.
Journal: FEBS Lett

miRNAs regulate gene expression by inhibiting translation or by targeting messenger RNA (mRNA) for degradation in a post-transcriptional fashion. In the present study, we show that ectopic expression of miR-34a reduces both mRNA and protein levels of cyclin D1 (CCND1) and cyclin-dependent kinase 6 (CDK6). We also demonstrate that miR-34a targets the 3'-untranslated mRNA region of CCND1 as well as CDK6, which in turn interferes with phosphorylation of retinoblastoma. In addition, we show that overexpression of miR-34a induces a significant G1 cell-cycle arrest in the A549 cell line. Taken together, our data suggest that the effects of miR-34a on G1 cell cycle arrest are through the down-regulation of CCND1 and CDK6, which is associated with other targets of miR-34a either additively or synergistically.

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Extracellular transglutaminase 2 activates beta-catenin signaling in calcifying vascular smooth muscle cells.

Publication Date: 2008 Apr 30 PMID: 18405667
Authors: Faverman, L. - Mikhaylova, L. - Malmquist, J. - Nurminskaya, M.
Journal: FEBS Lett

Accumulation of transglutaminase 2 (TG2) is often associated with mineral deposits in vasculature. Here, we demonstrate that purified TG2 stimulated a 3-fold increase in matrix mineralization and up-regulation of osteoblastic markers in cultured primary vascular smooth muscle cells (VSMCs). Extracellular TG2 interacts with the low density lipoprotein related-protein 5 receptor and activates beta-catenin signaling in VSMCs. These results suggest that TG2 may promote vascular calcification by activating the beta-catenin signaling pathway.

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Interferon gamma is recognised by importin alpha/beta: Enhanced nuclear localising and transactivation activities of an interferon gamma mimetic.

Publication Date: 2008 May 14 PMID: 18405666
Authors: Fulcher, A. J. - Ahmed, C. M. - Noon-Song, E. N. - Kwan, R. Y. - Subramaniam, P. S. - Johnson, H. M. - Jans, D. A.
Journal: FEBS Lett

Interferon (IFN) gamma's ability to localise in the nucleus and function in gene activation has been known for some time, although the role of the conventional nuclear transporting importin molecules is unclear. Here, we demonstrate for the first time the direct recognition of IFNgamma and an IFNgamma mimetic peptide by IMPalpha and the IMPalpha/beta heterodimer, where the IFNgamma mimetic shows higher affinity. Significantly, this correlates well both with in vivo ability to target green fluorescent protein to the nucleus in transfected cells as determined by quantitative confocal laser scanning microscopy, as well as GAS promoter activity of a luciferase reporter. This has important implications for IFNgamma's anti-viral action, and the potential use of the IFNgamma mimetic in antiviral therapies. STRUCTURED SUMMARY:

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The vacuolar V(1)/V(0)-ATPase is involved in the release of the HOPS subunit Vps41 from vacuoles, vacuole fragmentation and fusion.

Publication Date: 2008 Apr 30 PMID: 18405665
Authors: Takeda, K. - Cabrera, M. - Rohde, J. - Bausch, D. - Jensen, O. N. - Ungermann, C.
Journal: FEBS Lett

At yeast vacuoles, phosphorylation of the HOPS subunit Vps41 depends on the Yck3 kinase. In a screen for mutants that mimic the yck3Delta phenotype, in which Vps41 accumulates in vacuolar dots, we observed that mutants in the V(0)-part of the V(0)/V(1)-ATPase, in particular in vma16Delta, also accumulate Vps41. This accumulation is not due to a phosphorylation defect, but to reduced release of Vps41 from vma16Delta vacuoles. One reason could be a connection to vacuole fission, which is blocked in V-ATPase mutants. Vacuole fusion is not impaired between vacuoles lacking the V(0)-subunits Vma16 or Vma6 and wild-type vacuoles, whereas fusion between mutant vacuoles is reduced. Our data suggest a connection between vacuole biogenesis and membrane fusion.

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Neuronal nitric oxide synthase: Prototype for pulsed enzymology.

Publication Date: 2008 Apr 30 PMID: 18396171
Authors: Salerno, J. C.
Journal: FEBS Lett

The established paradigm in understanding and describing enzyme activity uses formalisms based on steady-state assumptions, including Michaelis-Menten and King-Altman approaches. These are appropriate for enzymes operating under steady-state conditions. Signal generating enzymes transfer information, rather than material. Because the information capacity of a signal channel depends on frequency, steady-state descriptions may not be appropriate. Recently, Stuehr and coworkers described a novel product inhibition mechanism for NO synthases. Simulations presented here suggest that at physiological temperatures neuronal nitric oxide synthase produces sharp pulses of NO, consistent with its signaling function. These temporal pulses greatly restrict the effective spatial range of NO signaling.

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Molybdate transport through the plant sulfate transporter SHST1.

Publication Date: 2008 Apr 30 PMID: 18396170
Authors: Fitzpatrick, K. L. - Tyerman, S. D. - Kaiser, B. N.
Journal: FEBS Lett

Molybdenum is an essential micronutrient required by plants. The mechanism of molybdenum uptake in plants is poorly understood, however, evidence has suggested that sulfate transporters may be involved. The sulfate transporter from Stylosanthes hamata, SHST1, restored growth of the sulfate transport yeast mutant, YSD1, on media containing low amounts of molybdate. Kinetic analysis using (99)MoO(4)(2-) demonstrated that SHST1 enhanced the uptake of molybdate into yeast cells at nM concentrations. Uptake was not inhibited by sulfate, but sulfate transport via SHST1 was reduced with molybdate. These results are the first measurement of molybdate transport by a characterised plant sulfate transport protein.

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Indole and other aromatic compounds activate the yeast TRPY1 channel.

Publication Date: 2008 Apr 30 PMID: 18396169
Authors: John Haynes, W. - Zhou, X. L. - Su, Z. W. - Loukin, S. H. - Saimi, Y. - Kung, C.
Journal: FEBS Lett

The yeast TRPY1 (Yvc1p) channel is activated by membrane stretch to release vacuolar Ca(2+) into the cytoplasm upon osmotic upshock. Exogenously added indole greatly enhances the upshock-induced Ca(2+) release in vivo. Indole also reversibly activates the channels under patch clamp. A minimum of 10(-6)M Ca(2+) is needed for membrane stretch force to open TPRY1, but indole activation appears to be Ca(2+) independent. A deletion of 30 residues at the predicted cytoplasmic domain, 570-600Delta, renders TRPY1 insensitive to stretch force upto 10(-3)M Ca(2+). Nonetheless, indole readily activates this mutant channel. Several other aromatic compounds, e.g. the antimicrobial parabens, also activate TRPY1. These compounds likely alter the innate forces in the lipid bilayer received by the channel.

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Delineating the susceptibility of botulinum neurotoxins to denaturation through thermal effects.

Publication Date: 2008 Apr 30 PMID: 18396167
Authors: Zhou, B. - Pellett, S. - Tepp, W. H. - Zhou, H. - Johnson, E. A. - Janda, K. D.
Journal: FEBS Lett

Botulinum neurotoxins (BoNT) are the etiological agents responsible for botulism and are acknowledged terrorist threat agents. Passive immunotherapy may provide one countermeasure. Importantly, in the virtually unlimited repertoire of antibody specificities, enzyme linked immunosorbent assays (ELISA) has become an indispensable method for antibody selection. We report that of the BoNTs, BoNT/E is highly susceptible to polystyrene induced denaturation. To further dissect this result and the potential susceptibility of other BoNTs to denaturation we selected a thermal platform, which could be readily quantified using surface plasmon resonance (SPR), a primary rat spinal cord cell-based assay and an animal lethality model.

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Lil3 assembles as chlorophyll-binding protein complex during deetiolation.

Publication Date: 2008 Apr 30 PMID: 18396166
Authors: Reisinger, V. - Ploscher, M. - Eichacker, L. A.
Journal: FEBS Lett

Dark-grown angiosperm seedlings are etiolated and devoid of chlorophyll. Deetiolation is triggered by light leading to chlorophyll dependent accumulation of the photosynthetic machinery. The transfer of chlorophyll to the chlorophyll-binding proteins is still unclear. We demonstrate here that upon illumination of dark-grown barley seedlings, two new pigment-binding protein complexes are de novo accumulated. Pigments bound to both complexes are identified as chlorophyll a and protochlorophyll a. By auto-fluorescence tracking and mass spectrometry, we show that exclusively Lil3 is the pigment-binding complex subunit in both complexes.

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Hydrogen-deuterium exchange strategy for delineation of contact sites in protein complexes.

Publication Date: 2008 Apr 30 PMID: 18396165
Authors: Dyson, H. J. - Kostic, M. - Liu, J. - Martinez-Yamout, M. A.
Journal: FEBS Lett

We use NMR spectra to determine protein-protein contact sites by observing differences in amide proton hydrogen-deuterium exchange in the complex compared to the free protein in solution. Aprotic organic solvents are used to preserve H/D labeling patterns that would be scrambled in water solutions. The binding site between the mammalian co-chaperone Aha1 with the middle domain of the chaperone Hsp90 obtained by our H/D exchange method corresponds well with that in the X-ray crystal structure of the homologous complex from yeast, even to the observation of a secondary binding site. This method can potentially provide data for complexes with unknown structure and for large or dynamic complexes inaccessible via NMR and X-ray methods.

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Possible role of a taurine transporter in the deep-sea mussel Bathymodiolus septemdierum in adaptation to hydrothermal vents.

Publication Date: 2008 Apr 30 PMID: 18396164
Authors: Inoue, K. - Tsukuda, K. - Koito, T. - Miyazaki, Y. - Hosoi, M. - Kado, R. - Miyazaki, N. - Toyohara, H.
Journal: FEBS Lett

Various invertebrates inhabiting hydrothermal vents possess sulfur-oxidizing bacteria in their tissues; however, the mechanisms by which toxic sulfides are delivered to these endosymbionts remain unknown. Recently, detoxification of sulfides using thiotaurine, a sulfur-containing amino acid, has been suggested. In this study, we propose the involvement of a taurine transporter in sulfide detoxification in the deep-sea mussel Bathymodiolus septemdierum by demonstrating: (i) the abundance of its mRNA in the gill; (ii) its activity under a wide range of salinities; (iii) its low Michaelis constant value in taurine transportation; and (iv) its affinity for thiotaurine and the thiotaurine precursor, hypotaurine.

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Role of the repressor JDP2 in the amino acid-regulated transcription of CHOP.

Publication Date: 2008 Apr 30 PMID: 18396163
Authors: Cherasse, Y. - Chaveroux, C. - Jousse, C. - Maurin, A. C. - Carraro, V. - Parry, L. - Fafournoux, P. - Bruhat, A.
Journal: FEBS Lett

The transcriptional activation of CHOP (C/EBP-homologous protein) by amino acid deprivation involves ATF2 and ATF4 binding at the amino acid response element within the promoter. In this report, we investigate the role of JDP2 (Jun Dimerization Protein 2) in the amino acid control of CHOP transcription following amino acid starvation. Our results show that JDP2 binds to the CHOP AARE in unstimulated cells and that its binding decreases following amino acid starvation. We demonstrate that JDP2 acts as a repressor and suggest that it could be functionally associated with HDAC3 to inhibit CHOP transcription.

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Cytochrome c is released from coupled mitochondria of yeast en route to acetic acid-induced programmed cell death and can work as an electron donor and a ROS scavenger.

Publication Date: 2008 Apr 30 PMID: 18396162
Authors: Giannattasio, S. - Atlante, A. - Antonacci, L. - Guaragnella, N. - Lattanzio, P. - Passarella, S. - Marra, E.
Journal: FEBS Lett

To gain insight into the processes by which acetic acid-induced programmed cell death (AA-PCD) takes place in yeast, we investigated both cytochrome c release from yeast mitochondria and mitochondrial coupling over the time course of AA-PCD. We show that the majority of cytochrome c release occurs early in AA-PCD from intact coupled mitochondria which undergo only gradual impairment. The released cytochrome c can be reduced both by ascorbate and by superoxide anion and in turn be oxidized via cytochrome c oxidase, thus working both as a ROS scavenger and a respiratory substrate. Late in AA-PCD, the released cytochrome c is degraded.

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The Lhcb protein and xanthophyll composition of the light harvesting antenna controls the DeltapH-dependency of non-photochemical quenching in Arabidopsis thaliana.

Publication Date: 2008 Apr 30 PMID: 18396161
Authors: Perez-Bueno, M. L. - Johnson, M. P. - Zia, A. - Ruban, A. V. - Horton, P.
Journal: FEBS Lett

Nonphotochemical quenching (NPQ) is the photoprotective dissipation of energy in photosynthetic membranes. The hypothesis that the DeltapH-dependent component of NPQ (qE) component of non-photochemical quenching is controlled allosterically by the xanthophyll cycle has been tested using Arabidopsis mutants with different xanthophyll content and composition of Lhcb proteins. The titration curves of qE against DeltapH were different in chloroplasts containing zeaxanthin or violaxanthin, proving their roles as allosteric activator and inhibitor, respectively. The curves differed in mutants deficient in lutein and specific Lhcb proteins. The results show that qE is determined by xanthophyll occupancy and the structural interactions within the antenna that govern allostericity.

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Intracellular delivery of acetyl-histone peptides inhibits native bromodomain-chromatin interactions and impairs mitotic progression.

Publication Date: 2008 Apr 30 PMID: 18396160
Authors: Nishiyama, A. - Mochizuki, K. - Mueller, F. - Karpova, T. - McNally, J. G. - Ozato, K.
Journal: FEBS Lett

Bromodomains present in Brd4 and other chromatin proteins interact with acetylated histones to regulate transcription and cell growth. To study Brd4-chromatin interactions in vivo, histone H4 tail peptides were fused to a synthetic protein transduction domain (PTD) derived from the human immunodeficiency virus Tat and delivered into cultured cells. Acetyl-H4 peptides, but not unacetylated H4 peptides inhibited real time Brd4-chromatin interactions in living cells as assessed by fluorescence recovery after photobleaching assays. The acetyl-H4 peptides also inhibited an interaction of Brd4 with chromosomes during mitosis and reduced cell growth potential. Together, PTD-based delivery of histone tail peptides offers a novel means to study the mechanism and biological significance of bromodomain-chromatin interactions in vivo.

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One SmpB molecule accompanies tmRNA during its passage through the ribosomes.

Publication Date: 2008 Apr 30 PMID: 18396159
Authors: Bugaeva, E. Y. - Shpanchenko, O. V. - Felden, B. - Isaksson, L. A. - Dontsova, O. A.
Journal: FEBS Lett

tmRNA and SmpB are the main participants of trans-translation, a process which rescues the ribosome blocked during translation of non-stop mRNA. While a one-to-one stoichiometry of tmRNA to the ribosome is generally accepted, the number of SmpB molecules in the complex is still under question. We have isolated tmRNA-ribosome complexes blocked at different steps of the tmRNA path through the ribosome and analyzed the stoichiometry of the complexes. Ribosome, tmRNA and SmpB were found in equimolar amount in the tmRNA-ribosome complexes stopped at the position of the 2nd, 4th, 5th or the 11th codons of the coding part of the tmRNA.

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Spectroelectrochemistry of cytochrome b559 in the D1-D2-Cyt b559 complex from spinach.

Publication Date: 2008 Apr 30 PMID: 18396158
Authors: Shibamoto, T. - Kato, Y. - Watanabe, T.
Journal: FEBS Lett

The redox potential of cytochrome b559 (Cyt b559) in the D1-D2-Cyt b559 complex from spinach has been determined to be +90+/-2mV vs. SHE at pH 6.0, by thin-layer cell spectroelectrochemistry for the first time. The redox potential, corresponding uniquely to the so-called "low-potential form", exhibited a sigmoidal pH-dependence from pH 4.0 to 9.0, ranging from +115 to +50mV. An analysis of the pH-dependence based on model equations suggests that two histidine residues coordinating to the heme iron in the protein subunits may exert electrostatic influence on the redox potential of Cyt b559.

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AdipoR1 mediates the anorexigenic and insulin/leptin-like actions of adiponectin in the hypothalamus.

Publication Date: 2008 Apr 30 PMID: 18394428
Authors: Coope, A. - Milanski, M. - Araujo, E. P. - Tambascia, M. - Saad, M. J. - Geloneze, B. - Velloso, L. A.
Journal: FEBS Lett

Adiponectin exerts an insulin-sensitizing effect, improving insulin action in peripheral tissues and restraining insulin resistance. Here, we explore the hypothesis that adiponectin can reproduce some of the actions of insulin/leptin in the hypothalamus. The presence of AdipoR1 and AdipoR2 was mapped to the arcuate and lateral hypothalamic nuclei. Icv adiponectin reduced food intake, which was accompanied by activation/engagement of IRS1/2, ERK, Akt, FOXO1, JAK2 and STAT3. All these actions were dependent on AdipoR1, since inhibition of this receptor, and not of AdipoR2, completely reversed the effects described above. Thus, adiponectin acts in the hypothalamus, activating elements of the canonical insulin and leptin signaling pathways and promoting reduction of food intake.

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Small heat shock protein Hsp27 protects myosin S1 from heat-induced aggregation, but not from thermal denaturation and ATPase inactivation.

Publication Date: 2008 Apr 30 PMID: 18387368
Authors: Markov, D. I. - Pivovarova, A. V. - Chernik, I. S. - Gusev, N. B. - Levitsky, D. I.
Journal: FEBS Lett

We applied different methods, such as turbidity measurements, dynamic light scattering, differential scanning calorimetry and co-sedimentation assay, to analyze the interaction of small heat shock protein Hsp27 with isolated myosin head (myosin subfragment 1, S1) under heat-stress conditions. Upon heating at 43 degrees C, Hsp27 effectively suppresses S1 aggregation, and this effect is enhanced by mutations mimicking Hsp27 phosphorylation. However, Hsp27 was unable to prevent thermal unfolding of myosin heads and to maintain their ATPase activity under heat-shock conditions. STRUCTURED SUMMARY:

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Parkin-co-regulated gene (PACRG) product interacts with tubulin and microtubules.

Publication Date: 2008 Apr 30 PMID: 18387367
Authors: Ikeda, T.
Journal: FEBS Lett

Parkin-co-regulated gene (PACRG) is a gene that shares a bidirectional promoter with Parkinson's disease-related Parkin/Park2 gene. Recently, the PACRG gene product was implicated in the function of flagella. However, its exact function remains unknown. Here, I assessed the interaction between PACRG and tubulin. Co-sedimentation experiments revealed that PACRG directly binds to microtubules and alpha/beta-tubulin heterodimers with high affinity. Microscopic studies showed that PACRG bundles microtubules and forms branched aggregates with unpolymerized tubulin dimers. The amino acid sequence of the microtubule-binding region of PACRG is highly conserved among various organisms, suggesting that tubulin binding is a basic property of PACRG. STRUCTURED SUMMARY:

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Mapping of interaction domains of putative telomere-binding proteins AtTRB1 and AtPOT1b from Arabidopsis thaliana.

Publication Date: 2008 Apr 30 PMID: 18387366
Authors: Schrumpfova, P. P. - Kuchar, M. - Palecek, J. - Fajkus, J.
Journal: FEBS Lett

We previously searched for interactions between plant telomere-binding proteins and found that AtTRB1, from the single-myb-histone (Smh) family, interacts with the Arabidopsis POT1-like-protein, AtPOT1b, involved in telomere capping. Here we identify domains responsible for that interaction. We also map domains in AtTRB1 responsible for interactions with other Smh-family-members. Our results show that the N-terminal OB-fold-domain of AtPOT1b mediates the interaction with AtTRB1. This domain is characteristic for POT1- proteins and is involved with binding the G-rich-strand of telomeric DNA. AtPOT1b also interacts with AtTRB2 and AtTRB3. The central histone-globular-domain of AtTRB1 is involved with binding to AtTRB2 and 3, as well as to AtPOT1b. AtTRB1-heterodimers with other Smh-family-members are more stable than AtTRB1-homodimers. Our results reveal interaction networks of plant telomeres. STRUCTURED SUMMARY:

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Detection of cross-links between FtsH, YidC, HflK/C suggests a linked role for these proteins in quality control upon insertion of bacterial inner membrane proteins.

Publication Date: 2008 Apr 30 PMID: 18387365
Authors: van Bloois, E. - Dekker, H. L. - Froderberg, L. - Houben, E. N. - Urbanus, M. L. - de Koster, C. G. - de Gier, J. W. - Luirink, J.
Journal: FEBS Lett

Little is known about the quality control of proteins upon integration in the inner membrane of Escherichia coli. Here, we demonstrate that YidC and FtsH are adjacent to a nascent, truncated membrane protein using in vitro photo cross-linking. YidC plays a critical but poorly understood role in the biogenesis of E. coli inner membrane proteins (IMPs). FtsH functions as a membrane chaperone and protease. Furthermore, we show that FtsH and its modulator proteins HflK and HflC copurify with tagged YidC and, vice versa, that YidC copurifies with tagged FtsH. These results suggest that FtsH and YidC have a linked role in the quality control of IMPs. STRUCTURED SUMMARY:

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The mammalian Nek1 kinase is involved in primary cilium formation.

Publication Date: 2008 Apr 30 PMID: 18387364
Authors: Shalom, O. - Shalva, N. - Altschuler, Y. - Motro, B.
Journal: FEBS Lett

Recent studies implicate primary cilium (PC) proteins in the etiologies of various polycystic kidney diseases (PKD). NIMA-related kinases (NRKs) are conserved serine/threonine kinases, which are usually defined as 'mitotic kinases'. Murine mutants for the NRKs, nek1 (kat mice) suffer from PKD, suggesting that it may be involved in cilium control. We demonstrated herein that Nek1 is localized to basal body region and that Nek1 overexpression inhibits ciliogenesis in Madin-Darby canine kidney epithelial cells. The number of primary cilia is dramatically reduced in kat2J mouse embryonic fibroblasts culture. It is thus hypothesized that Nek1 links cell cycle progression and the PC cycle.

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Establishment of the culture model system that reflects the process of terminal differentiation of connective tissue-type mast cells.

Publication Date: 2008 Apr 30 PMID: 18381075
Authors: Takano, H. - Nakazawa, S. - Okuno, Y. - Shirata, N. - Tsuchiya, S. - Kainoh, T. - Takamatsu, S. - Furuta, K. - Taketomi, Y. - Naito, Y. - Takematsu, H. - Kozutsumi, Y. - Tsujimoto, G. - Murakami, M. - Kudo, I. - Ichikawa, A. - Nakayama, K. - Sugimoto, Y. - Tanaka, S.
Journal: FEBS Lett

To understand physiological roles of tissue mast cells, we established a culture system where bone marrow-derived immature mast cells differentiate into the connective tissue-type mast cell (CTMC)-like cells through modifying the previous co-culture system with Swiss 3T3 fibroblasts. Our system was found to reproducibly mimic the differentiation of CTMCs on the basis of several criteria, such as granule maturation and sensitivity to cationic secretagogues. The gene expression profile obtained by the microarray analyses was found to reflect many aspects of the differentiation. Our system is thus helpful to gain deeper insights into terminal differentiation of CTMCs.

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Small mitochondrial ARF (smARF) is located in both the nucleus and cytoplasm, induces cell death, and activates p53 in mouse fibroblasts.

Publication Date: 2008 Apr 30 PMID: 18381074
Authors: Ueda, Y. - Koya, T. - Yoneda-Kato, N. - Kato, J. Y.
Journal: FEBS Lett

The ARF transcript produces two proteins, the full-length ARF, p19(ARF), and a short mitochondrial version, smARF. To explore the functional difference between the two, we generated GFP-fused expression vectors for each protein and introduced them into NIH3T3 murine fibroblasts, which sustains a global deletion in the INK4a locus but contains a functional p53 gene. GFP-p19(ARF) was located within the nucleolus as previously reported, whereas GFP-smARF was detected mainly in the nucleoplasm. GFP-smARF induced cell death although to a slightly lesser extent than p19(ARF). GFP-smARF stabilized p53 thereby inducing expression of the target genes, MDM2 and p21. We suggest that smARF has functions other than mitochondria-mediated autophagy, and induces p53 expression and cell death via a novel mechanism.

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Osteoactivin is a novel osteoclastic protein and plays a key role in osteoclast differentiation and activity.

Publication Date: 2008 Apr 30 PMID: 18381073
Authors: Sheng, M. H. - Wergedal, J. E. - Mohan, S. - Lau, K. H.
Journal: FEBS Lett

This study presents gene expression, protein expression, and in situ immunohistochemical evidence that osteoclasts express high levels of osteoactivin (OA), which had previously been reported to be an osteoblast-specific protein in bone. OA expression in osteoclasts was up-regulated upon receptor activator of NFkappaB ligand-induced differentiation. Suppression of functional activity of OA with neutralizing antibody reduced cell size, number of nuclei, fusion, and bone resorption activity of osteoclasts. OA was co-immunoprecipitated with integrin beta(3) and beta(1), indicating that OA co-localizes with integrin beta(3) and/or beta(1) in a hetero-polymeric complex in osteoclasts. These findings indicate that OA is a novel osteoclastic protein and plays a role in osteoclast differentiation and/or activity.

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Dynamics of Cdc42 network embodies a Turing-type mechanism of yeast cell polarity.

Publication Date: 2008 Apr 30 PMID: 18381072
Authors: Goryachev, A. B. - Pokhilko, A. V.
Journal: FEBS Lett

Complex biochemical networks can be understood by identifying their principal regulatory motifs and mode of action. We model the early phase of budding yeast cellular polarization and show that the biochemical processes in the presumptive bud site comprise a Turing-type mechanism. The roles of the prototypical activator and substrate are played by GTPase Cdc42 in its active and inactive states, respectively. We demonstrate that the nucleotide cycling of Cdc42 converts cellular energy into a stable cluster of activated Cdc42. This energy drives a continuous membrane-cytoplasmic exchange of the cluster components to counteract diffusive spread of the cluster. This exchange explains why only one bud forms per cell cycle, because the winner-takes-all competition of candidate sites inevitably selects a single site.

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Protein arginine (N)-methyl transferase 7 (PRMT7) as a potential target for the sensitization of tumor cells to camptothecins.

Publication Date: 2008 Apr 30 PMID: 18381071
Authors: Verbiest, V. - Montaudon, D. - Tautu, M. T. - Moukarzel, J. - Portail, J. P. - Markovits, J. - Robert, J. - Ichas, F. - Pourquier, P.
Journal: FEBS Lett

PRMT7 belongs to the protein arginine methyl-transferases family. We show that downregulation of PRMT7alpha and beta isoforms in DC-3F hamster cells was associated with increased sensitivity to the Top1 inhibitor camptothecin (CPT). This effect was not due to a change in Top1 contents or catalytic activity, or to a difference in the reversal of DNA breaks. Overexpression of PRMT7alpha and beta in DC-3F cells had no effect on CPT sensitivity, whereas it conferred a resistance to DC-3F/9-OH-E cells for which both isoforms are reduced by two- to three-fold as compared to DC-3F parental cells. Finally, downregulation of the human PRMT7 could also sensitize HeLa cells to CPT, suggesting that it could be used as a target to potentiate CPT derivatives.

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