scholarly journals Nuclear actin regulates inducible transcription by enhancing RNA polymerase II clustering

2019 ◽  
Author(s):  
Mian Wei ◽  
Xiaoying Fan ◽  
Miao Ding ◽  
Ruifeng Li ◽  
Shipeng Shao ◽  
...  

AbstractGene expression in response to external stimuli underlies a variety of fundamental cellular processes. However, how the transcription machinery is regulated under these scenarios is largely unknown. Here, we discover a novel role of nuclear actin in inducible transcriptional regulation using next-generation transcriptome sequencing and super-resolution microscopy. The RNA-seq data reveal that nuclear actin is required for the establishment of the serum-induced transcriptional program. Using super-resolution imaging, we found a remarkable enhancement of RNA polymerase II (Pol II) clustering upon serum stimulation and this enhancement requires the presence of nuclear actin. To study the molecular mechanisms, we firstly observed that Pol II clusters co-localized with the serum-response genes and nuclear actin polymerized in adjacent to Pol II clusters upon serum stimulation. Furthermore, N-WASP and Arp2/3 are reported to interact with Pol II, and we demonstrated N-WASP is required for serum-enhanced Pol II clustering. Importantly, using an optogenetic tool, we revealed that N-WASP phase-separated with the carboxy-terminal domain of Pol II and nuclear actin. In addition to serum stimulation, we found nuclear actin also essential in enhancing Pol II clustering upon interferon-γ treatment. Taken together, our work unveils nuclear actin promotes the formation of transcription factory on inducible genes, acting as a general mechanism underlying the rapid response to environmental cues.

2020 ◽  
Vol 6 (16) ◽  
pp. eaay6515 ◽  
Author(s):  
Mian Wei ◽  
Xiaoying Fan ◽  
Miao Ding ◽  
Ruifeng Li ◽  
Shipeng Shao ◽  
...  

Gene expression in response to stimuli underlies many fundamental processes. However, how transcription is regulated under these scenarios is largely unknown. Here, we find a previously unknown role of nuclear actin in transcriptional regulation. The RNA-seq data reveal that nuclear actin is required for the serum-induced transcriptional program. Using super-resolution imaging, we found a remarkable enhancement of RNA polymerase II (Pol II) clustering upon serum stimulation, and this enhancement requires nuclear actin. Pol II clusters colocalized with the serum-response genes and nuclear actin filaments upon serum stimulation. Furthermore, N-WASP is required for serum-enhanced Pol II clustering. N-WASP phase-separated with Pol II and nuclear actin. In addition to serum stimulation, nuclear actin also enhanced Pol II clustering upon interferon-γ treatment. Together, our work unveils that nuclear actin promotes the formation of transcription factory on inducible genes, acting as a general mechanism underlying the rapid response to environmental cues.


eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Won-Ki Cho ◽  
Namrata Jayanth ◽  
Brian P English ◽  
Takuma Inoue ◽  
J Owen Andrews ◽  
...  

Protein clustering is a hallmark of genome regulation in mammalian cells. However, the dynamic molecular processes involved make it difficult to correlate clustering with functional consequences in vivo. We developed a live-cell super-resolution approach to uncover the correlation between mRNA synthesis and the dynamics of RNA Polymerase II (Pol II) clusters at a gene locus. For endogenous β-actin genes in mouse embryonic fibroblasts, we observe that short-lived (~8 s) Pol II clusters correlate with basal mRNA output. During serum stimulation, a stereotyped increase in Pol II cluster lifetime correlates with a proportionate increase in the number of mRNAs synthesized. Our findings suggest that transient clustering of Pol II may constitute a pre-transcriptional regulatory event that predictably modulates nascent mRNA output.


2003 ◽  
Vol 23 (8) ◽  
pp. 2914-2926 ◽  
Author(s):  
Tomomichi Watanabe ◽  
Kazuhiro Hayashi ◽  
Aki Tanaka ◽  
Tadashi Furumoto ◽  
Fumio Hanaoka ◽  
...  

ABSTRACT The general transcription factor TFIIE plays essential roles in both transcription initiation and the transition from initiation to elongation. Previously, we systematically deleted the structural motifs and characteristic sequences of the small subunit of human TFIIE (hTFIIEβ) to map its functional regions. Here we introduced point mutations into two regions located near the carboxy terminus of hTFIIEβ and identified the functionally essential amino acid residues that bind to RNA polymerase II (Pol II), the general transcription factors, and single-stranded DNA. Although most residues identified were essential for transcription initiation, use of an in vitro transcription assay with a linearized template revealed that several residues in the carboxy-terminal helix-loop region are crucially involved in the transition stage. Mutations in these residues also affected the ability of hTFIIEβ to stimulate TFIIH-mediated phosphorylation of the carboxy-terminal heptapeptide repeats of the largest subunit of Pol II. Furthermore, these mutations conspicuously augmented the binding of hTFIIEβ to the p44 subunit of TFIIH. The antibody study indicated that they thus altered the conformation of one side of TFIIH, consisting of p44, XPD, and Cdk-activating kinase subunits, that is essential for the transition stage. This is an important clue for elucidating the molecular mechanisms involved in the transition stage.


2006 ◽  
Vol 26 (8) ◽  
pp. 3135-3148 ◽  
Author(s):  
Hongfang Qiu ◽  
Cuihua Hu ◽  
Chi-Ming Wong ◽  
Alan G. Hinnebusch

ABSTRACT The Paf1 complex (Paf1C) interacts with RNA polymerase II (Pol II) and promotes histone methylation of transcribed coding sequences, but the mechanism of Paf1C recruitment is unknown. We show that Paf1C is not recruited directly by the activator Gcn4p but is dependent on preinitiation complex assembly and Ser5 carboxy-terminal domain phosphorylation for optimal association with ARG1 coding sequences. Importantly, Spt4p is required for Paf1C occupancy at ARG1 (and other genes) and for Paf1C association with Ser5-phosphorylated Pol II in cell extracts, whereas Spt4p-Pol II association is independent of Paf1C. Since spt4Δ does not reduce levels of Pol II at ARG1, Ser5 phosphorylation, or Paf1C expression, it appears that Spt4p (or its partner in DSIF, Spt5p) provides a platform on Pol II for recruiting Paf1C following Ser5 phosphorylation and promoter clearance. spt4Δ reduces trimethylation of Lys4 on histone H3, demonstrating a new role for yeast DSIF in promoting a Paf1C-dependent function in elongation.


2004 ◽  
Vol 24 (20) ◽  
pp. 8963-8969 ◽  
Author(s):  
Gregory Bird ◽  
Diego A. R. Zorio ◽  
David L. Bentley

ABSTRACT We investigated the role of RNA polymerase II (pol II) carboxy-terminal domain (CTD) phosphorylation in pre-mRNA processing coupled and uncoupled from transcription in Xenopus oocytes. Inhibition of CTD phosphorylation by the kinase inhibitors 5,6-dichloro-1β-d-ribofuranosyl-benzimidazole and H8 blocked transcription-coupled splicing and poly(A) site cleavage. These experiments suggest that pol II CTD phosphorylation is required for efficient pre-mRNA splicing and 3′-end formation in vivo. In contrast, processing of injected pre-mRNA was unaffected by either kinase inhibitors or α-amanitin-induced depletion of pol II. pol II therefore does not appear to participate directly in posttranscriptional processing, at least in frog oocytes. Together these experiments show that the influence of the phosphorylated CTD on pre-mRNA splicing and 3′-end processing is mediated by transcriptional coupling.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  

The H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription at yeast promoters is responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.


Open Biology ◽  
2017 ◽  
Vol 7 (6) ◽  
pp. 170073 ◽  
Author(s):  
Joana Guiro ◽  
Shona Murphy

In addition to protein-coding genes, RNA polymerase II (pol II) transcribes numerous genes for non-coding RNAs, including the small-nuclear (sn)RNA genes. snRNAs are an important class of non-coding RNAs, several of which are involved in pre-mRNA splicing. The molecular mechanisms underlying expression of human pol II-transcribed snRNA genes are less well characterized than for protein-coding genes and there are important differences in expression of these two gene types. Here, we review the DNA features and proteins required for efficient transcription of snRNA genes and co-transcriptional 3′ end formation of the transcripts.


2001 ◽  
Vol 21 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Seiji Yamamoto ◽  
Yoshinori Watanabe ◽  
Peter J. van der Spek ◽  
Tomomichi Watanabe ◽  
Hiroyuki Fujimoto ◽  
...  

ABSTRACT The general transcription factor TFIIE plays important roles in transcription initiation and in the transition to elongation. However, little is known about its function during these steps. Here we demonstrate for the first time that TFIIH-mediated phosphorylation of RNA polymerase II (Pol II) is essential for the transition to elongation. This phosphorylation occurs at serine position 5 (Ser-5) of the carboxy-terminal domain (CTD) heptapeptide sequence of the largest subunit of Pol II. In a human in vitro transcription system with a supercoiled template, this process was studied using a human TFIIE (hTFIIE) homolog from Caenorhabditis elegans (ceTFIIEα and ceTFIIEβ). ceTFIIEβ could partially replace hTFIIEβ, whereas ceTFIIEα could not replace hTFIIEα. We present the studies of TFIIE binding to general transcription factors and the effects of subunit substitution on CTD phosphorylation. As a result, ceTFIIEα did not bind tightly to hTFIIEβ, and ceTFIIEβ showed a similar profile for binding to its human counterpart and supported an intermediate level of CTD phosphorylation. Using antibodies against phosphorylated serine at either Ser-2 or Ser-5 of the CTD, we found that ceTFIIEβ induced Ser-5 phosphorylation very little but induced Ser-2 phosphorylation normally, in contrast to wild-type hTFIIE, which induced phosphorylation at both Ser-2 and Ser-5. In transcription transition assays using a linear template, ceTFIIEβ was markedly defective in its ability to support the transition to elongation. These observations provide evidence of TFIIE involvement in the transition and suggest that Ser-5 phosphorylation is essential for Pol II to be in the processive elongation form.


2008 ◽  
Vol 28 (20) ◽  
pp. 6342-6357 ◽  
Author(s):  
Ales Obrdlik ◽  
Alexander Kukalev ◽  
Emilie Louvet ◽  
Ann-Kristin Östlund Farrants ◽  
Luca Caputo ◽  
...  

ABSTRACT 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.


eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Nicolas Descostes ◽  
Martin Heidemann ◽  
Lionel Spinelli ◽  
Roland Schüller ◽  
Muhammad Ahmad Maqbool ◽  
...  

In mammals, the carboxy-terminal domain (CTD) of RNA polymerase (Pol) II consists of 52 conserved heptapeptide repeats containing the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Post-translational modifications of the CTD coordinate the transcription cycle and various steps of mRNA maturation. Here we describe Tyr1 phosphorylation (Tyr1P) as a hallmark of promoter (5′ associated) Pol II in mammalian cells, in contrast to what was described in yeast. Tyr1P is predominantly found in antisense orientation at promoters but is also specifically enriched at active enhancers. Mutation of Tyr1 to phenylalanine (Y1F) prevents the formation of the hyper-phosphorylated Pol IIO form, induces degradation of Pol II to the truncated Pol IIB form, and results in a lethal phenotype. Our results suggest that Tyr1P has evolved specialized and essential functions in higher eukaryotes associated with antisense promoter and enhancer transcription, and Pol II stability.


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