Current Opinion in Cell Biology

Apoptosis: embedded in membranes.

Publication Date: 2010 Aug 26 PMID: 20801011
Authors: Bogner, C. - Leber, B. - Andrews, D. W.
Journal: Curr Opin Cell Biol

Many different signals for cell death converge on outer mitochondrial membrane permeabilization, a process controlled by the Bcl-2 family of proteins. Recent structural and biochemical analyses emphasize that key regulatory interactions between different classes of Bcl-2 family members occur at and in intracellular membranes, and insertion into membranes causes functionally important conformational changes in the proteins.

post to: CiteULike

Tube continued: morphogenesis of the Drosophila tracheal system.

Publication Date: 2010 Aug 23 PMID: 20739171
Authors: Schottenfeld, J. - Song, Y. - Ghabrial, A. S.
Journal: Curr Opin Cell Biol

The Drosophila respiratory organ (tracheal system) consists of epithelial tubes, the morphogenesis of which is controlled by distinct sets of signaling pathways and transcription factors. The downstream events controlling tube formation and shape are only now beginning to be identified. Here we review recent insight into the communication between neighboring tracheal cells, their interactions with the surrounding matrix, and the impact of these processes on tube morphogenesis. We focus on cell-cell interactions that drive rearrangement of cells within the epithelium and that are essential for maintenance of epithelial integrity, and also on cell-matrix interactions that play key roles in determining and maintaining the size and shape of tube lumens.

post to: CiteULike

Integration of planar cell polarity and ECM signaling in elongation of the vertebrate body plan.

Publication Date: 2010 Aug 23 PMID: 20739170
Authors: Skoglund, P. - Keller, R.
Journal: Curr Opin Cell Biol

The shaping of the vertebrate embryonic body plan depends heavily on the narrowing and lengthening (convergence and extension) of embryonic tissues by cell intercalation, a process by which cells actively crawl between one another along the axis of convergence to produce a narrower, longer array. We discuss recent evidence that the vertebrate non-canonical Wnt/Planar Cell Polarity (PCP) pathway, known to directly function in polarizing the movements of intercalating cells, is also involved in the localized assembly of extracellular matrix (ECM). These cell-ECM interactions, in turn, are necessary for expression of the oriented, polarized cell intercalation. The mechanism of PCP/ECM interactions, their molecular signaling, and their mechanical consequences for morphogenesis are discussed with the goal of identifying important unsolved issues.

post to: CiteULike

New role of the BCL2 family of proteins in the regulation of mitochondrial dynamics.

Publication Date: 2010 Aug 20 PMID: 20729050
Authors: Rolland, S. G. - Conradt, B.
Journal: Curr Opin Cell Biol

Mitochondria are highly dynamic organelles that constantly fuse and divide. Dynamin-related GTPases are the core components of the machineries that mediate mitochondrial fusion and fission. The role and regulation of these machineries are currently under intense investigation. Recently, members of the BCL2 family of proteins, conserved regulators of apoptosis, have been implicated in the regulation of mitochondrial dynamics. Here, we review the functions of mitochondrial fusion and fission in apoptotic and nonapoptotic cells and how members of the BCL2 family of proteins regulate these functions.

post to: CiteULike

Conserved F-actin dynamics and force transmission at cell adhesions.

Publication Date: 2010 Aug 19 PMID: 20728328
Authors: Maruthamuthu, V. - Aratyn-Schaus, Y. - Gardel, M. L.
Journal: Curr Opin Cell Biol

Adhesions are a central mechanism by which cells mechanically interact with the surrounding extracellular matrix (ECM) and neighboring cells. In both cell-ECM and cell-cell adhesions, forces generated within the actin cytoskeleton are transmitted to the surrounding environment and are essential for numerous morphogenic processes. Despite differences in many molecular components that regulate cell-cell and cell-ECM adhesions, the roles of F-actin dynamics and mechanical forces in adhesion regulation are surprisingly similar. Moreover, force transmission at adhesions occurs concomitantly with dynamic F-actin; proteins comprising the adhesion of F-actin to the plasma membrane must accommodate this movement while still facilitating force transmission. Thus, despite different molecular architectures, integrin and cadherin-mediated adhesions operate with common biophysical characteristics to transmit and respond to mechanical forces in multicellular tissue.

post to: CiteULike

Cyclin-dependent kinase-dependent initiation of chromosomal DNA replication.

Publication Date: 2010 Aug 19 PMID: 20728327
Authors: Araki, H.
Journal: Curr Opin Cell Biol

Cyclin-dependent kinase (CDK) is essential for the initiation of chromosomal DNA replication. CDK phosphorylates two yeast replication proteins, Sld2 and Sld3, both of which bind to another replication protein, Dpb11 when phosphorylated. These interactions are essential and are the minimal requirements for CDK activation of chromosomal DNA replication. This review discusses how these phosphorylation-dependent interactions initiate DNA replication through the formation of the pre-loading complex (pre-LC) and its interaction with phosphorylated Sld3 on replication origins. These steps are further regulated by multisite phosphorylation of Sld2. Sld3, on the other hand, must be turned over to reassociate with origins. Pol varepsilon functions as a component of the pre-LC as well as a replicative DNA polymerase at replication forks.

post to: CiteULike

Cell adhesion in regulation of asymmetric stem cell division.

Publication Date: 2010 Aug 17 PMID: 20724132
Authors: Yamashita, Y. M.
Journal: Curr Opin Cell Biol

Adult stem cells inevitably communicate with their cellular neighbors within the tissues they sustain. Indeed, such communication, particularly with components of the stem cell niche, is essential for many aspects of stem cell behavior, including the maintenance of stem cell identity and asymmetric cell division. Cell adhesion mediates this communication by placing stem cells in proximity to the signaling source and by providing a polarity cue that orients stem cells. Here, I review the recent discovery that cell adhesion molecules govern the behavior of stem cells.

post to: CiteULike

VE-cadherin: at the front, center, and sides of endothelial cell organization and function.

Publication Date: 2010 Aug 11 PMID: 20708398
Authors: Harris, E. S. - Nelson, W. J.
Journal: Curr Opin Cell Biol

Endothelial cells form cell-cell adhesive structures, called adherens and tight junctions, which maintain tissue integrity, but must be dynamic for leukocyte transmigration during the inflammatory response and cellular remodeling during angiogenesis. This review will focus on Vascular Endothelial (VE)-cadherin, an endothelial-specific cell-cell adhesion protein of the adherens junction complex. VE-cadherin plays a key role in endothelial barrier function and angiogenesis, and consequently VE-cadherin availability and function are tightly regulated. VE-cadherin also participates directly and indirectly in intracellular signaling pathways that control cell dynamics and cell cycle progression. Here we highlight recent work that has advanced our understanding of multiple regulatory and signaling mechanisms that converge on VE-cadherin and have consequences for endothelial barrier function and angiogenic remodeling.

post to: CiteULike

Nuclear and spindle positioning during oocyte meiosis.

Publication Date: 2010 Aug 11 PMID: 20708397
Authors: Fabritius, A. S. - Ellefson, M. L. - McNally, F. J.
Journal: Curr Opin Cell Biol

Female meiosis is unique in that an asymmetrically positioned meiotic spindle expels chromosomes into tiny, non-developing polar bodies. The extrusion of chromosomes into polar bodies is always mediated by meiotic spindles that are attached to the oocyte cortex by one pole. The asymmetric, cortical positioning of the oocyte meiotic spindle preserves the volume and contents of the oocyte. Recent work in C. elegans and mouse has provided mechanistic details of spindle positioning in oocytes.

post to: CiteULike

Kinetochore assembly: if you build it, they will come.

Publication Date: 2010 Aug 9 PMID: 20702077
Authors: Gascoigne, K. E. - Cheeseman, I. M.
Journal: Curr Opin Cell Biol

Accurate chromosome segregation requires the interaction of chromosomes with the microtubules from the mitotic spindle. This interaction is mediated by the macro-molecular kinetochore complex, which assembles only at the centromeric region of each chromosome. However, how this site is specified and how assembly of the kinetochore structure is regulated in coordination with cell cycle progression remains unclear. Recent studies have begun to shed light on the mechanisms underlying assembly of this complex structure.

post to: CiteULike