scholarly journals A Ras-Dependent Pathway Regulates RNA Polymerase II Phosphorylation in Cardiac Myocytes: Implications for Cardiac Hypertrophy

1998 ◽  
Vol 18 (11) ◽  
pp. 6729-6736 ◽  
Author(s):  
Maha Abdellatif ◽  
Sharon E. Packer ◽  
Lloyd H. Michael ◽  
Dou Zhang ◽  
Min Ji Charng ◽  
...  

ABSTRACT Despite extensive evidence implicating Ras in cardiac muscle hypertrophy, the mechanisms involved are unclear. We previously reported that Ras, through an effector-like function of Ras GTPase-activating protein (GAP) in neonatal cardiac myocytes (M. Abdellatif et al., J. Biol. Chem. 269:15423–15426, 1994; M. Abdellatif and M. D. Schneider, J. Biol. Chem. 272:527–533, 1997), can up-regulate expression from a comprehensive set of promoters, including both cardiac cell-specific and constitutive ones. To investigate the mechanism(s) underlying these earlier findings, we have used recombinant adenoviruses harboring a dominant negative Ras (17N Ras) allele or the N-terminal domain of GAP (nGAP), responsible for the Ras-like effector function. Inhibition of endogenous Ras reduced basal levels of [3H]uridine and [3H]phenylalanine incorporation into total RNA, mRNA, and protein, with parallel changes in apparent cell size. In addition, 17N Ras markedly inhibited phosphorylation of the C-terminal domain (CTD) of RNA polymerase II (pol II), known to regulate transcript elongation, accompanied by down-regulation of its principal kinase, cyclin-dependent kinase 7 (Cdk7). In contrast, nGAP elicited the opposite effects on each of these parameters. Furthermore, cotransfection of constitutively active Ras (12R Ras) with wild-type pol II, rather than a truncated mutant lacking the CTD, demonstrated that Ras activation of transcription was dependent on the pol II CTD. Consistent with a potential role for this pathway in the development of cardiac myocyte hypertrophy, α1-adrenergic stimulation similarly enhanced pol II phosphorylation and Cdk7 expression, where both effects were inhibited by dominant negative Ras, while pressure overload hypertrophy led to an increase in both hyperphosphorylated and hypophosphorylated pol II in addition to Cdk7.

1998 ◽  
Vol 18 (4) ◽  
pp. 2130-2142 ◽  
Author(s):  
Lei Lei ◽  
Delin Ren ◽  
Ann Finkelstein ◽  
Zachary F. Burton

ABSTRACT Transcription factor IIF (TFIIF) cooperates with RNA polymerase II (pol II) during multiple stages of the transcription cycle including preinitiation complex assembly, initiation, elongation, and possibly termination and recycling. Human TFIIF appears to be an α2β2 heterotetramer of RNA polymerase II-associating protein 74- and 30-kDa subunits (RAP74 and RAP30). From inspection of its 517-amino-acid (aa) sequence, the RAP74 subunit appears to comprise separate N- and C-terminal domains connected by a flexible loop. In this study, we present functional data that strongly support this model for RAP74 architecture and further show that the N- and C-terminal domains and the central loop of RAP74 have distinct roles during separate phases of the transcription cycle. The N-terminal domain of RAP74 (minimally aa 1 to 172) is sufficient to deliver pol II into a complex formed on the adenovirus major late promoter with the TATA-binding protein, TFIIB, and RAP30. A more complete N-terminal domain fragment (aa 1 to 217) strongly stimulates both accurate initiation and elongation by pol II. The region of RAP74 between aa 172 and 205 and a subregion between aa 170 and 178 are critical for both accurate initiation and elongation, and mutations in these regions have similar effects on initiation and elongation. Based on these observations, RAP74 appears to have similar functions in initiation and elongation. The central region and the C-terminal domain of RAP74 do not contribute strongly to single-round accurate initiation or elongation stimulation but do stimulate multiple-round transcription in an extract system.


2020 ◽  
Vol 117 (33) ◽  
pp. 19888-19895
Author(s):  
Haolin Liu ◽  
Srinivas Ramachandran ◽  
Nova Fong ◽  
Tzu Phang ◽  
Schuyler Lee ◽  
...  

More than 30% of genes in higher eukaryotes are regulated by RNA polymerase II (Pol II) promoter proximal pausing. Pausing is released by the positive transcription elongation factor complex (P-TEFb). However, the exact mechanism by which this occurs and whether phosphorylation of the carboxyl-terminal domain of Pol II is involved in the process remains unknown. We previously reported that JMJD5 could generate tailless nucleosomes at position +1 from transcription start sites (TSS), thus perhaps enable progression of Pol II. Here we find that knockout of JMJD5 leads to accumulation of nucleosomes at position +1. Absence of JMJD5 also results in loss of or lowered transcription of a large number of genes. Interestingly, we found that phosphorylation, by CDK9, of Ser2 within two neighboring heptad repeats in the carboxyl-terminal domain of Pol II, together with phosphorylation of Ser5 within the second repeat, HR-Ser2p (1, 2)-Ser5p (2) for short, allows Pol II to bind JMJD5 via engagement of the N-terminal domain of JMJD5. We suggest that these events bring JMJD5 near the nucleosome at position +1, thus allowing JMJD5 to clip histones on this nucleosome, a phenomenon that may contribute to release of Pol II pausing.


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.


2007 ◽  
Vol 27 (6) ◽  
pp. 2059-2073 ◽  
Author(s):  
Victoria H. Cowling ◽  
Michael D. Cole

ABSTRACT Myc is a transcription factor which is dependent on its DNA binding domain for transcriptional regulation of target genes. Here, we report the surprising finding that Myc mutants devoid of direct DNA binding activity and Myc target gene regulation can rescue a substantial fraction of the growth defect in myc −/− fibroblasts. Expression of the Myc transactivation domain alone induces a transcription-independent elevation of the RNA polymerase II (Pol II) C-terminal domain (CTD) kinases cyclin-dependent kinase 7 (CDK7) and CDK9 and a global increase in CTD phosphorylation. The Myc transactivation domain binds to the transcription initiation sites of these promoters and stimulates TFIIH binding in an MBII-dependent manner. Expression of the Myc transactivation domain increases CDK mRNA cap methylation, polysome loading, and the rate of translation. We find that some traditional Myc transcriptional target genes are also regulated by this Myc-driven translation mechanism. We propose that Myc transactivation domain-driven RNA Pol II CTD phosphorylation has broad effects on both transcription and mRNA metabolism.


2002 ◽  
Vol 364 (3) ◽  
pp. 649-657 ◽  
Author(s):  
Sergei NEKHAI ◽  
Meisheng ZHOU ◽  
Anne FERNANDEZ ◽  
William S. LANE ◽  
Ned J.C. LAMB ◽  
...  

HIV-1 gene expression is regulated by a viral transactivator protein (Tat) which induces transcriptional elongation of HIV-1 long tandem repeat (LTR). This induction requires hyperphosphorylation of the C-terminal domain (CTD) repeats of RNA polymerase II (Pol II). To achieve CTD hyperphosphorylation, Tat stimulates CTD kinases associated with general transcription factors of the promoter complex, specifically TFIIH-associated CDK7 and positive transcription factor b-associated CDK9 (cyclin-dependent kinase 9). Other studies indicate that Tat may bind an additional CTD kinase that regulates the target-specific phosphorylation of RNA Pol II CTD. We previously reported that Tat-associated T-cell-derived kinase (TTK), purified from human primary T-cells, stimulates Tat-dependent transcription of HIV-1 LTR in vivo [Nekhai, Shukla, Fernandez, Kumar and Lamb (2000) Virology 266, 246–256]. In the work presented here, we characterized the components of TTK by biochemical fractionation and the function of TTK in transcription assays in vitro. TTK uniquely co-purified with CDK2 and not with either CDK9 or CDK7. Tat induced the TTK-associated CDK2 kinase to phosphorylate CTD, specifically at Ser-2 residues. The TTK fraction restored Tat-mediated transcription activation of HIV-1 LTR in a HeLa nuclear extract immunodepleted of CDK9, but not in the HeLa nuclear extract double-depleted of CDK9 and CDK7. Direct microinjection of the TTK fraction augmented Tat transactivation of HIV-1 LTR in human primary HS68 fibroblasts. The results argue that TTK-associated CDK2 may function to maintain target-specific phosphorylation of RNA Pol II that is essential for Tat transactivation of HIV-1 promoter. They are also consistent with the observed cell-cycle-specific induction of viral gene transactivation.


2009 ◽  
Vol 29 (20) ◽  
pp. 5455-5464 ◽  
Author(s):  
Kira Glover-Cutter ◽  
Stéphane Larochelle ◽  
Benjamin Erickson ◽  
Chao Zhang ◽  
Kevan Shokat ◽  
...  

ABSTRACT The function of human TFIIH-associated Cdk7 in RNA polymerase II (Pol II) transcription and C-terminal domain (CTD) phosphorylation was investigated in analogue-sensitive Cdk7 as/as mutant cells where the kinase can be inhibited without disrupting TFIIH. We show that both Cdk7 and Cdk9/PTEFb contribute to phosphorylation of Pol II CTD Ser5 residues on transcribed genes. Cdk7 is also a major kinase of CTD Ser7 on Pol II at the c-fos and U snRNA genes. Furthermore, TFIIH and recombinant Cdk7-CycH-Mat1 as well as recombinant Cdk9-CycT1 phosphorylated CTD Ser7 and Ser5 residues in vitro. Inhibition of Cdk7 in vivo suppressed the amount of Pol II accumulated at 5′ ends on several genes including c-myc, p21, and glyceraldehyde-3-phosphate dehydrogenase genes, indicating reduced promoter-proximal pausing or polymerase “leaking” into the gene. Consistent with a 5′ pausing defect, Cdk7 inhibition reduced recruitment of the negative elongation factor NELF at start sites. A role of Cdk7 in regulating elongation is further suggested by enhanced histone H4 acetylation and diminished histone H4 trimethylation on lysine 36—two marks of elongation—within genes when the kinase was inhibited. Consistent with a new role for TFIIH at 3′ ends, it was detected within genes and 3′-flanking regions, and Cdk7 inhibition delayed pausing and transcription termination.


2005 ◽  
Vol 25 (21) ◽  
pp. 9406-9418 ◽  
Author(s):  
Ashish Saxena ◽  
Beicong Ma ◽  
Laura Schramm ◽  
Nouria Hernandez

ABSTRACT The transcription factors TFIIB, Brf1, and Brf2 share related N-terminal zinc ribbon and core domains. TFIIB bridges RNA polymerase II (Pol II) with the promoter-bound preinitiation complex, whereas Brf1 and Brf2 are involved, as part of activities also containing TBP and Bdp1 and referred to here as Brf1-TFIIIB and Brf2-TFIIIB, in the recruitment of Pol III. Brf1-TFIIIB recruits Pol III to type 1 and 2 promoters and Brf2-TFIIIB to type 3 promoters such as the human U6 promoter. Brf1 and Brf2 both have a C-terminal extension absent in TFIIB, but their C-terminal extensions are unrelated. In yeast Brf1, the C-terminal extension interacts with the TBP/TATA box complex and contributes to the recruitment of Bdp1. Here we have tested truncated Brf2, as well as Brf2/TFIIB chimeric proteins for U6 transcription and for assembly of U6 preinitiation complexes. Our results characterize functions of various human Brf2 domains and reveal that the C-terminal domain is required for efficient association of the protein with U6 promoter-bound TBP and SNAPc, a type 3 promoter-specific transcription factor, and for efficient recruitment of Bdp1. This in turn suggests that the C-terminal extensions in Brf1 and Brf2 are crucial to specific recruitment of Pol III over Pol II.


2008 ◽  
Vol 36 (3) ◽  
pp. 537-539 ◽  
Author(s):  
Sylvain Egloff ◽  
Shona Murphy

Pol II (RNA polymerase II) transcribes the genes encoding proteins and non-coding snRNAs (small nuclear RNAs). The largest subunit of Pol II contains a distinctive CTD (C-terminal domain) comprising a repetitive heptad amino acid sequence, Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. This domain is now known to play a major role in the processes of transcription and co-transcriptional RNA processing in expression of both snRNA and protein-coding genes. The heptapeptide repeat unit can be extensively modified in vivo and covalent modifications of the CTD during the transcription cycle result in the ordered recruitment of RNA-processing factors. The most studied modifications are the phosphorylation of the serine residues in position 2 and 5 (Ser2 and Ser5), which play an important role in the co-transcriptional processing of both mRNA and snRNA. An additional, recently identified CTD modification, phosphorylation of the serine residue in position 7 (Ser7) of the heptapeptide, is however specifically required for expression of snRNA genes. These findings provide interesting insights into the control of gene-specific Pol II function.


2020 ◽  
Vol 48 (14) ◽  
pp. 7712-7727
Author(s):  
Michael Tellier ◽  
Justyna Zaborowska ◽  
Livia Caizzi ◽  
Eusra Mohammad ◽  
Taras Velychko ◽  
...  

Abstract Cyclin-dependent kinase 12 (CDK12) phosphorylates the carboxyl-terminal domain (CTD) of RNA polymerase II (pol II) but its roles in transcription beyond the expression of DNA damage response genes remain unclear. Here, we have used TT-seq and mNET-seq to monitor the direct effects of rapid CDK12 inhibition on transcription activity and CTD phosphorylation in human cells. CDK12 inhibition causes a genome-wide defect in transcription elongation and a global reduction of CTD Ser2 and Ser5 phosphorylation. The elongation defect is explained by the loss of the elongation factors LEO1 and CDC73, part of PAF1 complex, and SPT6 from the newly-elongating pol II. Our results indicate that CDK12 is a general activator of pol II transcription elongation and indicate that it targets both Ser2 and Ser5 residues of the pol II CTD.


2004 ◽  
Vol 24 (2) ◽  
pp. 846-855 ◽  
Author(s):  
Erica Y. Jacobs ◽  
Ikuo Ogiwara ◽  
Alan M. Weiner

ABSTRACT U small nuclear RNAs (snRNAs) and mRNAs are both transcribed by RNA polymerase II (Pol II), but the snRNAs have unusual TATA-less promoters and are neither spliced nor polyadenylated; instead, 3′ processing is directed by a highly conserved 3′ end formation signal that requires initiation from an snRNA promoter. Here we show that the C-terminal domain (CTD) of Pol II is required for efficient U2 snRNA transcription, as it is for mRNA transcription. However, CTD kinase inhibitors, such as 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), that block mRNA elongation do not affect U2 transcription, although 3′ processing of the U2 primary transcript is impaired. We show further that U2 transcription is preferentially inhibited by low doses of UV irradiation or actinomycin D, which induce CTD kinase activity, and that UV inhibition can be rescued by treatment with DRB or H7. We propose that Pol II complexes transcribing snRNAs and mRNAs have distinct CTD phosphorylation patterns. mRNA promoters recruit factors including kinases that hyperphosphorylate the CTD, and the CTD in turn recruits proteins needed for mRNA splicing and polyadenylation. We predict that snRNA promoters recruit factors including a CTD kinase(s) whose snRNA-specific phosphorylation pattern recruits factors required for promoter-coupled 3′ end formation.


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