Trends in biochemical sciences

Non-coding RNAs: key regulators of mammalian transcription.

Publication Date: 2012 Jan 31 PMID: 22300815
Authors: Kugel, J. F. - Goodrich, J. A.
Journal: Trends Biochem Sci

Non-coding RNAs (ncRNAs) are now recognized as active participants in controlling many biological processes. Indeed, these products of transcription can even control the process of transcription itself. In the past several years, ncRNAs have been found to regulate transcription of single genes, as well as entire transcriptional programs, affecting the expression of hundreds to thousands of genes in response to developmental or environmental signals. Compared to more classical protein regulators, the list of ncRNAs that regulate mRNA transcription in mammalian cells is still small; however, the rate at which new ncRNA transcriptional regulators are being discovered is rapid, suggesting that models for how gene expression is controlled will continue to be redefined as this field develops.

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DNA base excision repair: a mechanism of trinucleotide repeat expansion.

Publication Date: 2012 Jan 27 PMID: 22285516
Authors: Liu, Y. - Wilson, S. H.
Journal: Trends Biochem Sci

The expansion of trinucleotide repeat (TNR) sequences in human DNA is considered to be a key factor in the pathogenesis of more than 40 neurodegenerative diseases. TNR expansion occurs during DNA replication and also, as suggested by recent studies, during the repair of DNA lesions produced by oxidative stress. In particular, the oxidized guanine base 8-oxoguanine within sequences containing CAG repeats may induce formation of pro-expansion intermediates through strand slippage during DNA base excision repair (BER). In this article, we describe how oxidized DNA lesions are repaired by BER and discuss the importance of the coordinated activities of the key repair enzymes, such as DNA polymerase beta, flap endonuclease 1 (FEN1) and DNA ligase, in preventing strand slippage and TNR expansion.

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Biogenesis of multisubunit RNA polymerases.

Publication Date: 2012 Jan 17 PMID: 22260999
Authors: Wild, T. - Cramer, P.
Journal: Trends Biochem Sci

Gene transcription in the nucleus of eukaryotic cells is carried out by three related multisubunit RNA polymerases, Pol I, Pol II and Pol III. Although the structure and function of the polymerases have been studied extensively, little is known about their biogenesis and their transport from the cytoplasm (where the subunits are synthesized) to the nucleus. Recent studies have revealed polymerase assembly intermediates and putative assembly factors, as well as factors required for Pol II nuclear import. In this review, we integrate the available data into a model of Pol II biogenesis that provides a framework for future analysis of the biogenesis of all RNA polymerases.

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How do plants feel the heat?

Publication Date: 2012 Jan 9 PMID: 22236506
Authors: Mittler, R. - Finka, A. - Goloubinoff, P.
Journal: Trends Biochem Sci

In plants, the heat stress response (HSR) is highly conserved and involves multiple pathways, regulatory networks and cellular compartments. At least four putative sensors have recently been proposed to trigger the HSR. They include a plasma membrane channel that initiates an inward calcium flux, a histone sensor in the nucleus, and two unfolded protein sensors in the endoplasmic reticulum and the cytosol. Each of these putative sensors is thought to activate a similar set of HSR genes leading to enhanced thermotolerance, but the relationship between the different pathways and their hierarchical order is unclear. In this review, we explore the possible involvement of different thermosensors in the plant response to warming and heat stress.

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