Actin's latest act: polymerizing to facilitate transcription?

Vieu, Erwann; Hernandez, Nouria

doi:10.1038/ncb0706-650

Cited by 14 publications

(10 citation statements)

References 16 publications

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“…Based on this finding, we propose that the cooperative regulatory function of actin, hnRNP U, and PCAF on pol II transcription elongation is likely to be dependent on the presence of nascent RNA transcripts. Consistent with recent findings of the involvement of N-WASP and the ARP2/3 complex in later phases of pol II transcription (31,36), actin-mediated pol II transcriptional control may be sensitive to the different polymerization states of actin (30). Actin filaments that can be identified by phalloidin staining in the cytoplasm have not yet been revealed in the cell nucleus (reviewed in reference 22).…”

Section: Discussionsupporting

confidence: 63%

The Histone Acetyltransferase PCAF Associates with Actin and hnRNP U for RNA Polymerase II Transcription

Obrdlík

Kukalev

Louvet

et al. 2008

Molecular and Cellular Biology

134

161

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Actin is a key regulator of RNA polymerase (pol) II transcription. In complex with specific hnRNPs, it has been proposed that actin functions to recruit pol II coactivators during the elongation of nascent transcripts. Here, we show by affinity chromatography, protein-protein interaction assays, and biochemical fractionation of nuclear extracts that the histone acetyltransferase (HAT) PCAF associates with actin and hnRNP U. PCAF and the nuclear actin-associated HAT activity detected in the DNase I-bound protein fraction could be released by disruption of the actin-hnRNP U complex. In addition, actin, hnRNP U, and PCAF were found to be associated with the Ser2/5-and Ser2-phosphorylated pol II carboxy-terminal domain construct. Chromatin and RNA immunoprecipitation assays demonstrated that actin, hnRNP U, and PCAF are present at the promoters and coding regions of constitutively expressed pol II genes and that they are associated with ribonucleoprotein complexes. Finally, disruption of the actin-hnRNP U interaction repressed bromouridine triphosphate incorporation in living cells, suggesting that actin and hnRNP U cooperate with PCAF in the regulation of pol II transcription elongation.Eukaryotic gene transcription requires dynamic alterations of chromatin structure that are mediated by chromatin remodeling complexes and histone modifying enzymes (23, 28).For transcription competence, histone acetylation allows the switch between repressive and permissive chromatin structures through direct effects on nucleosome stability and through establishment of binding sites for regulatory proteins. Considerable progress in understanding the role of histone acetylation came from the discovery that the Saccharomyces cerevisiae transcription coactivator GCN5 and, more recently, other yeast and metazoan transcription cofactors are histone acetyltransferases (HATs). Mammalian homologs of the yeast cofactor GCN5 include PCAF and GCN5L (2,27,32,33,35). PCAF and GCN5L are encoded by distinct genes, and their expressions are differential and complementary in various tissues (33,35). Moreover, GCN5L is essential for mouse development, whereas PCAF is dispensable (33, 34). Human GCN5L and PCAF form parts of distinct multiprotein HAT complexes, namely the PCAF complex (17), the TFTC complex (1), and the STAGA complex (12). While these mammalian HAT complexes are still incompletely characterized, they have related but not identical subunit compositions.PCAF/GCN5, together with the p300/CREB-binding protein, is among the best-studied transcriptional coactivators (11). PCAF has been proposed to facilitate long-distance transcriptional enhancement by direct association with enhancer sequences (7). PCAF is also known to acetylate free histones or nucleosomes, primarily on lysine 14 of histone H3 (28), and its requirement as coactivator or HAT has been demonstrated for myogenesis and nuclear receptor-mediated and growth factor-signaled activation (28). However, it is presently unclear whether PCAF is also involved in the maintenance of effic...

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Section: Discussionsupporting

confidence: 63%

The Histone Acetyltransferase PCAF Associates with Actin and hnRNP U for RNA Polymerase II Transcription

Obrdlík

Kukalev

Louvet

et al. 2008

Molecular and Cellular Biology

134

161

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“…Actin binds to a specific subset of premessenger RNA binding proteins to form a molecular platform for the recruitment of histone acetyltransferase or histone deacetylase complexes along the active transcription unit (30 -33), but the structural form of actin used in these processes remains unclear. Recent research on the N-WASP (neuronal WiskottAldrich Syndrome protein) and ARP2/3 complexes in Pol II transcription (34,35) showed that actin-mediated Pol II transcriptional regulation is sensitive to the state of actin polymerization (36). However, a new study suggested that actin may be present in a monomeric or oligomeric form that is different from canonical actin filaments (33).…”

mentioning

confidence: 98%

G-actin Participates in RNA Polymerase II-dependent Transcription Elongation by Recruiting Positive Transcription Elongation Factor b (P-TEFb)

Tang

Wang

et al. 2011

Journal of Biological Chemistry

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Actin is a key regulator of RNA polymerase (Pol) II-dependent transcription. Positive transcription elongation factor b (P-TEFb), a Cdk9/cyclin T1 heterodimer, has been reported to play a critical role in transcription elongation. However, the relationship between actin and P-TEFb is still not clear. In this study, actin was found to interact with Cdk9, a catalytic subunit of P-TEFb, in elongation complexes. Using immunofluorescence and immunoprecipitation assays, Cdk9 was found to bind to G-actin through the conserved Thr-186 in the T-loop. Overexpression and in vitro kinase assays showed that G-actin promotes P-TEFb-dependent phosphorylation of the Pol II C-terminal domain. An in vitro transcription experiment revealed that the interaction between G-actin and Cdk9 stimulated Pol II transcription elongation. ChIP and immobilized template assays indicated that actin recruited Cdk9 to a transcriptional template in vivo and in vitro. Using cytokine IL-6-inducible p21 gene expression system, we revealed that actin recruited Cdk9 to endogenous gene. Moreover, overexpression of actin and Cdk9 increased histone H3 acetylation and acetylized histone H3 binding to a transcriptional template through the interaction with histone acetyltransferase, p300. Taken together, our results suggested that actin participates in transcription elongation by recruiting Cdk9 for phosphorylation of the Pol II C-terminal domain, and the actin-Cdk9 interaction promotes chromatin remodeling.

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“…Posttranslational modifications (P, Ac, SUMO, Ub, Me...) of either NF B or cofactor complexes were found to affect cofactor complex associations and activities [123,124], dynamics of nucleocytoplasmic shuttling [125][126][127][128][129], nucleolar sequestration [130] or association with chaperone proteins (HMG, I B, hsp, 14-3-3) [131][132][133][134][135][136][137][138] and/or with subcellular structures (i.e. nuclear lamins, nuclear pore complex, actin skeleton, speckles, transcription factories, PML bodies, nucleoli) [139][140][141][142][143][144][145][146][147][148][149][150]. These dynamic enhanceosome complexes represent a level of signaling integration, whereby the activities of multiple upstream pathways converge to impress a distinct chromatin structure [151].…”

Section: From Enhanceosome To Histone Codementioning

confidence: 98%

Epigenetic Remedies by Dietary Phytochemicals Against Inflammatory Skin Disorders: Myth or Reality?

Berghe¹,

Haegeman²

2010

CDM

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While many botanicals have been used during thousands of years in various cultures for the treatment of several inflammatory conditions, wound healing or preserving skin beauty, their active ingredients and their mechanisms of action are less well characterized. It is known that throughout life, environmental conditions and dietary compounds influence gene expression. Only recently it has been observed that exposure to specific phytochemicals can affect gene expression via reversible epigenetic mechanisms and gets recorded in our "epigenome" through life. Epigenetics refers to heritable phenotypical differences or changes in gene expression that are not attributable to changes in DNA sequence, but rather depend on variations in DNA methylation, chromatin structure or microRNA profiles. As such, our dietary epigenetic imprint superposed on our genome may rewire gene expression patterns in the body and the host immune system, and protect against inflammatory disorders, cancer and ageing. This has recently launched reexploration of nutritional, botanical or phytopharmaceutical compounds for epigenetic effects to identify promising nutraceuticals or cosmeceuticals which could (re)program stem cell differentiation, wound healing, skin regeneration, tissue homeostasis, or "correct" epigenetic marks responsible for inflammatory skin disorders and ageing.

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Actin's latest act: polymerizing to facilitate transcription?

Cited by 14 publications

References 16 publications

The Histone Acetyltransferase PCAF Associates with Actin and hnRNP U for RNA Polymerase II Transcription

The Histone Acetyltransferase PCAF Associates with Actin and hnRNP U for RNA Polymerase II Transcription

G-actin Participates in RNA Polymerase II-dependent Transcription Elongation by Recruiting Positive Transcription Elongation Factor b (P-TEFb)

Epigenetic Remedies by Dietary Phytochemicals Against Inflammatory Skin Disorders: Myth or Reality?

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