Browsing by Subject "RNA polymerase II"

Now showing 1 - 3 of 3
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    Architectural Mediator subunits are differentially essential for global transcription in Saccharomyces cerevisiae
    (Oxford University Press, 2021) Tourigny, Jason P.; Schumacher, Kenny; Saleh, Moustafa M.; Devys, Didier; Zentner, Gabriel E.; Biology, School of Science
    Mediator is a modular coactivator complex involved in the transcription of the majority of RNA polymerase II-regulated genes. However, the degrees to which individual core subunits of Mediator contribute to its activity have been unclear. Here, we investigate the contribution of two essential architectural subunits of Mediator to transcription in Saccharomyces cerevisiae. We show that acute depletion of the main complex scaffold Med14 or the head module nucleator Med17 is lethal and results in global transcriptional downregulation, though Med17 removal has a markedly greater negative effect. Consistent with this, Med17 depletion impairs preinitiation complex (PIC) assembly to a greater extent than Med14 removal. Co-depletion of Med14 and Med17 reduced transcription and TFIIB promoter occupancy similarly to Med17 ablation alone, indicating that the contributions of Med14 and Med17 to Mediator function are not additive. We propose that, while the structural integrity of complete Mediator and the head module are both important for PIC assembly and transcription, the head module plays a greater role in this process and is thus the key functional module of Mediator in this regard.
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    CDK8/19 Mediator kinases potentiate induction of transcription by NFκB
    (National Academy of Sciences, 2017-09-19) Chen, Mengqian; Liang, Jiaxin; Ji, Hao; Yang, Zhengguan; Altilia, Serena; Hu, Bing; Schronce, Adam; McDermott, Martina S. J.; Schools, Gary P.; Lim, Chang-uk; Oliver, David; Shtutman, Michael S.; Lu, Tao; Stark, George R.; Porter, Donald C.; Broude, Eugenia V.; Roninson, Igor B.; Pharmacology and Toxicology, School of Medicine
    Nuclear factor-κB (NFκB) transcription factors have been implicated in several major diseases, including inflammatory disorders, viral infections, and cancer. NFκB-inhibiting drugs typically have side effects, possibly due to sustained NFκB suppression. The ability to affect induced, but not basal, NFκB activity could provide therapeutic benefit without associated toxicity. We report that the transcription-regulating kinases CDK8/19 potentiate NFκB activity, including the expression of tumor-promoting proinflammatory cytokines, by enabling the completion of NFκB-initiated transcription. CDK8/19 inhibitors suppress the induction of gene expression by NFκB or other transcription factors, but generally do not affect basal expression of the same genes. The role of CDK8/19 in newly induced transcription identifies these kinases as mediators of transcriptional reprogramming, a key aspect of development, differentiation, and pathological processes., The nuclear factor-κB (NFκB) family of transcription factors has been implicated in inflammatory disorders, viral infections, and cancer. Most of the drugs that inhibit NFκB show significant side effects, possibly due to sustained NFκB suppression. Drugs affecting induced, but not basal, NFκB activity may have the potential to provide therapeutic benefit without associated toxicity. NFκB activation by stress-inducible cell cycle inhibitor p21 was shown to be mediated by a p21-stimulated transcription-regulating kinase CDK8. CDK8 and its paralog CDK19, associated with the transcriptional Mediator complex, act as coregulators of several transcription factors implicated in cancer; CDK8/19 inhibitors are entering clinical development. Here we show that CDK8/19 inhibition by different small-molecule kinase inhibitors or shRNAs suppresses the elongation of NFκB-induced transcription when such transcription is activated by p21-independent canonical inducers, such as TNFα. On NFκB activation, CDK8/19 are corecruited with NFκB to the promoters of the responsive genes. Inhibition of CDK8/19 kinase activity suppresses the RNA polymerase II C-terminal domain phosphorylation required for transcriptional elongation, in a gene-specific manner. Genes coregulated by CDK8/19 and NFκB include IL8, CXCL1, and CXCL2, which encode tumor-promoting proinflammatory cytokines. Although it suppressed newly induced NFκB-driven transcription, CDK8/19 inhibition in most cases had no effect on the basal expression of NFκB-regulated genes or promoters; the same selective regulation of newly induced transcription was observed with other transcription signals potentiated by CDK8/19. This selective role of CDK8/19 identifies these kinases as mediators of transcriptional reprogramming, a key aspect of development and differentiation as well as pathological processes.
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    The role of the CTD phosphatase Rrt1 and post-translational modifications in regulation of RNA polymerase II
    (2014-07-07) Cox, Mary L.; Goebl, Mark G.; Mosley, Amber L.; Wek, Ronald C.
    RNA polymerase II (RNAPII) is regulated by multiple modifications to the C-terminal domain (CTD) of the largest subunit, Rpb1. This study has focused on the relationship between hyperphosphorylation of the CTD and RNAPII turnover and proteolytic degradation as well as post-translational modifications of the globular core of RNAPII. Following tandem affinity purification, western blot analysis showed that MG132 treated RTR1 ERG6 deletion yeast cells have accumulation of total RNAPII and in particular, the hyperphosphorylated form of the protein complex. In addition, proteomic studies using MuDPIT have revealed increased interaction between proteins of the ubiquitin-proteasome degradation system in the mutant MG132 treated yeast cells as well as potential ubiquitin and phosphorylation sites in RNAPII subunits, Rpb6 and Rpb1, respectively. A novel Rpb1 phosphorylation site, T1471-P, is located in the linker region between the CTD and globular domain of Rpb1 and will be the focus of future studies to determine biological significance of this post-translational modification.