4ec8

Structural highlights

Disease

[CDK9_HUMAN] Note=Chronic activation of CDK9 causes cardiac myocyte enlargement leading to cardiac hypertrophy, and confers predisposition to heart failure.

Function

[CDK9_HUMAN] Protein kinase involved in the regulation of transcription. Member of the cyclin-dependent kinase pair (CDK9/cyclin-T) complex, also called positive transcription elongation factor b (P-TEFb), which facilitates the transition from abortive to productive elongation by phosphorylating the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNAP II) POLR2A, SUPT5H and RDBP. This complex is inactive when in the 7SK snRNP complex form. Phosphorylates EP300, MYOD1, RPB1/POLR2A and AR, and the negative elongation factors DSIF and NELF. Regulates cytokine inducible transcription networks by facilitating promoter recognition of target transcription factors (e.g. TNF-inducible RELA/p65 activation and IL-6-inducible STAT3 signaling). Promotes RNA synthesis in genetic programs for cell growth, differentiation and viral pathogenesis. P-TEFb is also involved in cotranscriptional histone modification, mRNA processing and mRNA export. Modulates a complex network of chromatin modifications including histone H2B monoubiquitination (H2Bub1), H3 lysine 4 trimethylation (H3K4me3) and H3K36me3; integrates phosphorylation during transcription with chromatin modifications to control co-transcriptional histone mRNA processing. The CDK9/cyclin-K complex has also a kinase activity towards CTD of RNAP II and can substitute for CDK9/cyclin-T P-TEFb in vitro. Replication stress response protein; the CDK9/cyclin-K complex is required for genome integrity maintenance, by promoting cell cycle recovery from replication arrest and limiting single-stranded DNA amount in response to replication stress, thus reducing the breakdown of stalled replication forks and avoiding DNA damage. In addition, probable function in DNA repair of isoform 2 via interaction with KU70/XRCC6. Promotes cardiac myocyte enlargement. RPB1/POLR2A phosphorylation on 'Ser-2' in CTD activates transcription. AR phosphorylation modulates AR transcription factor promoter selectivity and cell growth. DSIF and NELF phosphorylation promotes transcription by inhibiting their negative effect. The phosphorylation of MYOD1 enhances its transcriptional activity and thus promotes muscle differentiation.^{[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22]} [CCNT1_HUMAN] Regulatory subunit of the cyclin-dependent kinase pair (CDK9/cyclin-T1) complex, also called positive transcription elongation factor B (P-TEFb), which is proposed to facilitate the transition from abortive to productive elongation by phosphorylating the CTD (carboxy-terminal domain) of the large subunit of RNA polymerase II (RNA Pol II). In case of HIV or SIV infections, binds to the transactivation domain of the viral nuclear transcriptional activator, Tat, thereby increasing Tat's affinity for the transactivating response RNA element (TAR RNA). Serves as an essential cofactor for Tat, by promoting RNA Pol II activation, allowing transcription of viral genes.

See Also

• Cyclin
• Cyclin-dependent kinase

References

1. ↑ Wada T, Takagi T, Yamaguchi Y, Watanabe D, Handa H. Evidence that P-TEFb alleviates the negative effect of DSIF on RNA polymerase II-dependent transcription in vitro. EMBO J. 1998 Dec 15;17(24):7395-403. PMID:9857195 doi:10.1093/emboj/17.24.7395
2. ↑ Parada CA, Roeder RG. A novel RNA polymerase II-containing complex potentiates Tat-enhanced HIV-1 transcription. EMBO J. 1999 Jul 1;18(13):3688-701. PMID:10393184 doi:10.1093/emboj/18.13.3688
3. ↑ Fu TJ, Peng J, Lee G, Price DH, Flores O. Cyclin K functions as a CDK9 regulatory subunit and participates in RNA polymerase II transcription. J Biol Chem. 1999 Dec 3;274(49):34527-30. PMID:10574912
4. ↑ Wada T, Orphanides G, Hasegawa J, Kim DK, Shima D, Yamaguchi Y, Fukuda A, Hisatake K, Oh S, Reinberg D, Handa H. FACT relieves DSIF/NELF-mediated inhibition of transcriptional elongation and reveals functional differences between P-TEFb and TFIIH. Mol Cell. 2000 Jun;5(6):1067-72. PMID:10912001
5. ↑ Ivanov D, Kwak YT, Guo J, Gaynor RB. Domains in the SPT5 protein that modulate its transcriptional regulatory properties. Mol Cell Biol. 2000 May;20(9):2970-83. PMID:10757782
6. ↑ Kim JB, Sharp PA. Positive transcription elongation factor B phosphorylates hSPT5 and RNA polymerase II carboxyl-terminal domain independently of cyclin-dependent kinase-activating kinase. J Biol Chem. 2001 Apr 13;276(15):12317-23. Epub 2001 Jan 5. PMID:11145967 doi:10.1074/jbc.M010908200
7. ↑ Ping YH, Rana TM. DSIF and NELF interact with RNA polymerase II elongation complex and HIV-1 Tat stimulates P-TEFb-mediated phosphorylation of RNA polymerase II and DSIF during transcription elongation. J Biol Chem. 2001 Apr 20;276(16):12951-8. Epub 2000 Dec 8. PMID:11112772 doi:10.1074/jbc.M006130200
8. ↑ Lavoie SB, Albert AL, Handa H, Vincent M, Bensaude O. The peptidyl-prolyl isomerase Pin1 interacts with hSpt5 phosphorylated by Cdk9. J Mol Biol. 2001 Sep 28;312(4):675-85. PMID:11575923 doi:10.1006/jmbi.2001.4991
9. ↑ Lin X, Taube R, Fujinaga K, Peterlin BM. P-TEFb containing cyclin K and Cdk9 can activate transcription via RNA. J Biol Chem. 2002 May 10;277(19):16873-8. Epub 2002 Mar 7. PMID:11884399 doi:10.1074/jbc.M200117200
10. ↑ Bourgeois CF, Kim YK, Churcher MJ, West MJ, Karn J. Spt5 cooperates with human immunodeficiency virus type 1 Tat by preventing premature RNA release at terminator sequences. Mol Cell Biol. 2002 Feb;22(4):1079-93. PMID:11809800
11. ↑ Simone C, Stiegler P, Bagella L, Pucci B, Bellan C, De Falco G, De Luca A, Guanti G, Puri PL, Giordano A. Activation of MyoD-dependent transcription by cdk9/cyclin T2. Oncogene. 2002 Jun 13;21(26):4137-48. PMID:12037670 doi:10.1038/sj.onc.1205493
12. ↑ Zhou M, Deng L, Lacoste V, Park HU, Pumfery A, Kashanchi F, Brady JN, Kumar A. Coordination of transcription factor phosphorylation and histone methylation by the P-TEFb kinase during human immunodeficiency virus type 1 transcription. J Virol. 2004 Dec;78(24):13522-33. PMID:15564463 doi:78/24/13522
13. ↑ Fujinaga K, Irwin D, Huang Y, Taube R, Kurosu T, Peterlin BM. Dynamics of human immunodeficiency virus transcription: P-TEFb phosphorylates RD and dissociates negative effectors from the transactivation response element. Mol Cell Biol. 2004 Jan;24(2):787-95. PMID:14701750
14. ↑ Hou T, Ray S, Brasier AR. The functional role of an interleukin 6-inducible CDK9.STAT3 complex in human gamma-fibrinogen gene expression. J Biol Chem. 2007 Dec 21;282(51):37091-102. Epub 2007 Oct 23. PMID:17956865 doi:10.1074/jbc.M706458200
15. ↑ Nowak DE, Tian B, Jamaluddin M, Boldogh I, Vergara LA, Choudhary S, Brasier AR. RelA Ser276 phosphorylation is required for activation of a subset of NF-kappaB-dependent genes by recruiting cyclin-dependent kinase 9/cyclin T1 complexes. Mol Cell Biol. 2008 Jun;28(11):3623-38. doi: 10.1128/MCB.01152-07. Epub 2008 Mar , 24. PMID:18362169 doi:10.1128/MCB.01152-07
16. ↑ Pirngruber J, Shchebet A, Johnsen SA. Insights into the function of the human P-TEFb component CDK9 in the regulation of chromatin modifications and co-transcriptional mRNA processing. Cell Cycle. 2009 Nov 15;8(22):3636-42. Epub 2009 Nov 24. PMID:19844166
17. ↑ Pirngruber J, Shchebet A, Schreiber L, Shema E, Minsky N, Chapman RD, Eick D, Aylon Y, Oren M, Johnsen SA. CDK9 directs H2B monoubiquitination and controls replication-dependent histone mRNA 3'-end processing. EMBO Rep. 2009 Aug;10(8):894-900. doi: 10.1038/embor.2009.108. Epub 2009 Jul 3. PMID:19575011 doi:10.1038/embor.2009.108
18. ↑ Liu H, Herrmann CH, Chiang K, Sung TL, Moon SH, Donehower LA, Rice AP. 55K isoform of CDK9 associates with Ku70 and is involved in DNA repair. Biochem Biophys Res Commun. 2010 Jun 25;397(2):245-50. doi:, 10.1016/j.bbrc.2010.05.092. Epub 2010 May 20. PMID:20493174 doi:10.1016/j.bbrc.2010.05.092
19. ↑ Yu DS, Zhao R, Hsu EL, Cayer J, Ye F, Guo Y, Shyr Y, Cortez D. Cyclin-dependent kinase 9-cyclin K functions in the replication stress response. EMBO Rep. 2010 Nov;11(11):876-82. doi: 10.1038/embor.2010.153. Epub 2010 Oct 8. PMID:20930849 doi:10.1038/embor.2010.153
20. ↑ Sunagawa Y, Morimoto T, Takaya T, Kaichi S, Wada H, Kawamura T, Fujita M, Shimatsu A, Kita T, Hasegawa K. Cyclin-dependent kinase-9 is a component of the p300/GATA4 complex required for phenylephrine-induced hypertrophy in cardiomyocytes. J Biol Chem. 2010 Mar 26;285(13):9556-68. doi: 10.1074/jbc.M109.070458. Epub 2010, Jan 17. PMID:20081228 doi:10.1074/jbc.M109.070458
21. ↑ Gordon V, Bhadel S, Wunderlich W, Zhang J, Ficarro SB, Mollah SA, Shabanowitz J, Hunt DF, Xenarios I, Hahn WC, Conaway M, Carey MF, Gioeli D. CDK9 regulates AR promoter selectivity and cell growth through serine 81 phosphorylation. Mol Endocrinol. 2010 Dec;24(12):2267-80. doi: 10.1210/me.2010-0238. Epub 2010 Oct, 27. PMID:20980437 doi:10.1210/me.2010-0238
22. ↑ Cojocaru M, Bouchard A, Cloutier P, Cooper JJ, Varzavand K, Price DH, Coulombe B. Transcription factor IIS cooperates with the E3 ligase UBR5 to ubiquitinate the CDK9 subunit of the positive transcription elongation factor B. J Biol Chem. 2011 Feb 18;286(7):5012-22. doi: 10.1074/jbc.M110.176628. Epub 2010 , Dec 2. PMID:21127351 doi:10.1074/jbc.M110.176628
23. ↑ Baumli S, Hole AJ, Wang LZ, Noble ME, Endicott JA. The CDK9 tail determines the reaction pathway of positive transcription elongation factor b. Structure. 2012 Oct 10;20(10):1788-95. doi: 10.1016/j.str.2012.08.011. Epub 2012 , Sep 6. PMID:22959624 doi:http://dx.doi.org/10.1016/j.str.2012.08.011