Targeting of CDK8 to a promoter-proximal RNA element demonstrates catalysis-dependent activation of gene expression

Gold, Moses O.; Rice, Andrew P.

doi:10.1093/nar/26.16.3784

Cited by 29 publications

(24 citation statements)

References 35 publications

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“…This artificial recruitment of P-TEFb through an RNA element required the kinase activity of Cdk9 (21). Activation must be through a different mechanism than that found in similar experiments with artificially recruited Cdk8 for which kinase activity was not required (28). Targeted recruitment of either Cdk9 or cyclin T1 to DNA targets also activates transcription, and when a Cdk9 mutant lacking kinase activity was used no activation was seen (46).…”

Section: Mechanism Of P-tefb Actionmentioning

confidence: 94%

P-TEFb, a Cyclin-Dependent Kinase Controlling Elongation by RNA Polymerase II

Price

2000

Molecular and Cellular Biology

625

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The elongation phase of transcription by RNA polymerase II is one of the many steps during the generation of mature mRNAs that is subject to regulation. Shortly after initiation, RNA polymerase II comes under the control of negative transcription elongation factors, generally termed N-TEFs, and enters abortive elongation (51). During this postinitiation process, only short transcripts are generated that may be prematurely terminated. These short transcripts arise from transcription of many genes, including c-myb, c-myc, c-fos, HSP70, and the human immunodeficiency virus (HIV) long terminal repeat (LTR), and are normally subject to rapid degradation (3,63). Escape from the action of N-TEF requires the action of at least one positive transcription elongation factor (P-TEF), eventually identified as P-TEFb (52). P-TEFb allows the transition into productive elongation, producing long transcripts from which mRNAs are derived. In this way, the fraction of initiating RNA polymerase II molecules that produce full-length transcripts is controlled by a selection process that occurs early in the elongation phase of the transcription cycle. After the transition is made into productive elongation, the efficiency of elongation may be influenced by additional factors, including S-II, TFIIF, ELL, and elongin (62, 65). IDENTIFICATION OF P-TEFBThe elongation control process was uncovered during studies aimed at understanding the mechanism of inhibition of transcription by 5,6-dichloro-1-␤-D-ribofuranosylbenzimidazole (DRB). Treatment of mammalian cells with DRB is lethal; however, the initial effect is a dramatic reduction of mRNA (64). DRB treatment caused the production of shortened transcripts from a variety of genes, suggesting that elongation by RNA polymerase II was affected (66). This interpretation was complicated by the finding that DRB had no effect on the enzymatic activity of purified RNA polymerase II (40). Fortunately, DRB did affect transcription by RNA polymerase II in vitro when crude nuclear extracts were used (12,82). A number of promoters were surveyed with a Drosophila melanogaster in vitro transcription system, and it was found that most of the RNA polymerase II molecules that initiated generated only short transcripts (51). Those polymerases that were able to reach the end of the template could not do so in the presence of DRB (51). Inhibition of the appearance of runoff transcripts by DRB became the hallmark of elongation control and made the requirement for P-TEFb apparent.Examination of RNA polymerase II elongation using pulsechase techniques or immobilized templates led to the elucidation of the general parameters of N-TEF and P-TEF function. The effects of N-TEF were suppressed by the addition of high salt concentrations or detergents so that all polymerases that initiated were able to reach runoff length (40). P-TEF was a limiting factor because under normal-salt conditions in the functional presence of N-TEF only a small fraction of the polymerases were able to reach runoff (51). Kinetic analysis ind...

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Section: Mechanism Of P-tefb Actionmentioning

confidence: 94%

P-TEFb, a Cyclin-Dependent Kinase Controlling Elongation by RNA Polymerase II

Price

2000

Molecular and Cellular Biology

625

491

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“…First, we studied CDK-8's kinase requirement using a kinase-dead CDK-8(D182A) transgene [CDK-8(KD)]. The D182A mutation is homologous to the previously reported D173A mutation in human CDK8 and the D290A mutation in budding yeast CDK8, both of which result in loss of enzymatic activity (Liao et al 1995;Gold and Rice 1998); however, we note that the kinase activity of C. elegans CDK-8(D182A) has not been tested directly. CDK-8(KD) did not rescue the cdk-8; lin-15A mutant Muv phenotype, and actually enhanced Muv penetrance ( Figure 4A), suggesting that kinase activity is required for transgenic rescue of the Muv phenotype of cdk-8 null mutants.…”

Section: Cdk-8 Activity Is Kinase Dependentmentioning

confidence: 99%

The Mediator Kinase Module Restrains Epidermal Growth Factor Receptor Signaling and Represses Vulval Cell Fate Specification in Caenorhabditis elegans

et al. 2015

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Cell signaling pathways that control proliferation and determine cell fates are tightly regulated to prevent developmental anomalies and cancer. Transcription factors and coregulators are important effectors of signaling pathway output, as they regulate downstream gene programs. In Caenorhabditis elegans, several subunits of the Mediator transcriptional coregulator complex promote or inhibit vulva development, but pertinent mechanisms are poorly defined. Here, we show that Mediator's dissociable cyclin dependent kinase 8 (CDK8) module (CKM), consisting of cdk-8, cic-1/Cyclin C, mdt-12/dpy-22, and mdt-13/let-19, is required to inhibit ectopic vulval cell fates downstream of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. cdk-8 inhibits ectopic vulva formation by acting downstream of mpk-1/ERK, cell autonomously in vulval cells, and in a kinasedependent manner. We also provide evidence that the CKM acts as a corepressor for the Ets-family transcription factor LIN-1, as cdk-8 promotes transcriptional repression by LIN-1. In addition, we find that CKM mutation alters Mediator subunit requirements in vulva development: the mdt-23/sur-2 subunit, which is required for vulva development in wild-type worms, is dispensable for ectopic vulva formation in CKM mutants, which instead display hallmarks of unrestrained Mediator tail module activity. We propose a model whereby the CKM controls EGFR-Ras-ERK transcriptional output by corepressing LIN-1 and by fine tuning Mediator specificity, thus balancing transcriptional repression vs. activation in a critical developmental signaling pathway. Collectively, these data offer an explanation for CKM repression of EGFR signaling output and ectopic vulva formation and provide the first evidence of Mediator CKM-tail module subunit crosstalk in animals.KEYWORDS Mediator complex; CDK8; MED23; MED15; EGFR; Notch P RECISE regulation of transcription is required to execute developmental programs such as proliferation and cell fate determination. The Mediator complex ("Mediator") is a conserved eukaryotic transcriptional coregulator of RNA polymerase II (Pol II) transcription (Malik and Roeder 2010;Poss et al. 2013). Mediator consists of 30 subunits that assemble into four modules. "Core" Mediator consists of three of the four modules: the head and middle modules, which contact Pol II, and the tail module, which serves as a docking site for transcription factors. The fourth module, the dissociable cyclin dependent kinase 8 (CDK8) kinase module (CKM), interacts with transcription factors, core Mediator, chromatin, and the Pol II machinery to either repress or activate transcription (Malik and Roeder 2010;Nemet et al. 2014 transcription, tail and CKM subunits regulate specific transcriptional programs in animal development or physiology (Malik and Roeder 2010;Nemet et al. 2014). The CKM consists of enzymatic subunits CDK8 and cyclin C, and structural subunits MED12 and MED13 that tether the CKM to core Mediator (Tsai et al. 2013). C...

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“…In addition to this crucial role in cell cycle regulation, CDK members have also been implicated in other fundamental biological processes, including transcription and neuronal function (3). As an example of the latter, Cdk5 is selectively active in neurons and, together with its noncyclin activators, p35 and p39, regulates numerous neuronal processes (4).…”

mentioning

confidence: 99%

Multiple cyclin-dependent kinases signals are critical mediators of ischemia/hypoxic neuronal death in vitro and in vivo

Rashidian

Iyirhiaro

Aleyasin

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

127

134

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The mechanisms involving neuronal death after ischemic͞hypoxic insult are complex, involving both rapid (excitotoxic) and delayed (apoptotic-like) processes. Recent evidence suggests that cell cycle regulators such as cyclin-dependent kinases are abnormally activated in neuropathological conditions, including stroke. However, the function of this activation is unclear. Here, we provide evidence that inhibition of the cell cycle regulator, Cdk4, and its activator, cyclinD1, plays critical roles in the delayed death component of ischemic͞hypoxic stress by regulating the tumor suppressor retinoblastoma protein. In contrast, the excitotoxic component of ischemia͞hypoxia is predominately regulated by Cdk5 and its activator p35, components of a cyclin-dependent kinase complex associated with neuronal development. Hence, our data both characterize the functional significance of the cell cycle Cdk4 and neuronal Cdk5 signals as well as define the pathways and circumstances by which they act to control ischemic͞hypoxic damage.hypoxia ͉ stroke

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Targeting of CDK8 to a promoter-proximal RNA element demonstrates catalysis-dependent activation of gene expression

Cited by 29 publications

References 35 publications

P-TEFb, a Cyclin-Dependent Kinase Controlling Elongation by RNA Polymerase II

P-TEFb, a Cyclin-Dependent Kinase Controlling Elongation by RNA Polymerase II

The Mediator Kinase Module Restrains Epidermal Growth Factor Receptor Signaling and Represses Vulval Cell Fate Specification in Caenorhabditis elegans

Multiple cyclin-dependent kinases signals are critical mediators of ischemia/hypoxic neuronal death in vitro and in vivo

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