Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclin-dependent kinase-9 (CDK9) was originally characterized as a transcription elongation factor which regulates RNA Polymerase II (RNAPII) activity following transcriptional initiation. However, recent evidence from a number of studies have shown that CDK9 plays an important role in regulating not only RNAPII activity but also co-transcriptional histone modification and mRNA processing events such as splicing and 3' end processing. Importantly, our previous work and the work presented here demonstrate that CDK9 functions to guide a complex network of chromatin modifications including histone H2B monoubiquitination (H2Bub1), H3 lysine 4 trimethylation (H3K4me3) and H3K36me3. This function appears to be dependent upon not only the phosphorylation of the RNA Polymerase II C-terminal domain but also upon other CDK9 targets such as the Suppressor of Ty Homolog-5 (SUPT5H), Negative Elongation Factor-E (NELF-E) and probably the human Rad6 homolog UBE2A. We provide a working model by which CDK9 may control co-transcriptional replication-dependent histone mRNA 3' end processing in an H2Bub1 and H3K4me3-dependent manner and uncover new and important differences between the functions of human CDK9 and its yeast counterparts Ctk1 and Bur1.
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PMID:Insights into the function of the human P-TEFb component CDK9 in the regulation of chromatin modifications and co-transcriptional mRNA processing. 1984 66

Cyclin-dependent kinase-9 (CDK9) plays a central role in transcriptional elongation and controls multiple cotranscriptional histone modifications, including histone H2B monoubiquitination (H2Bub1). Like other CDK9-dependent histone modifications, the role of CDK9 in maintaining H2Bub1 was shown to be partially dependent upon the phosphorylation status of Ser2 of the RNA polymerase II (RNAPII) C-terminal domain (CTD). Since mutation of Ser2 within the RNAPII CTD resulted in a milder effect on H2Bub1 compared with CDK9 knockdown, we explored whether another CDK9 target may also influence H2Bub1. Based on its homology to yeast Bur1, we hypothesized that CDK9 may directly phosphorylate and activate the ubiquitin-conjugating enzyme utilized for H2B monoubiquitination. Indeed, we demonstrate that UBE2A specifically interacts with CDK9, but not CDK2. Furthermore, UBE2A is phosphorylated by CDK9 in vitro and increases UBE2A activity. Interestingly, CDK9 knockdown not only decreases UBE2A phosphorylation and H2Bub1, but also significantly impairs the induction of UBE2A-dependent monoubiquitination of proliferating cell nuclear antigen (PCNA). Thus, we provide the first evidence that CDK9 is required for the activity of UBE2A in humans, and that its activity is not only required for maintaining H2Bub1, but also for the monoubiquitination of PCNA. The common involvement of these two ubiquitinations in distinct DNA repair pathways may provide a mechanistic rationale for further exploring CDK9 as a combinatorial target for increasing the efficacy of existing cancer therapies based on the induction of DNA damage and are repaired by mechanisms which require H2Bub1 and/or PCNA ubiquitination.
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PMID:Phosphorylation by cyclin-dependent kinase-9 controls ubiquitin-conjugating enzyme-2A function. 2272 97