Activation and function of cyclin T-Cdk9 (positive transcription elongation factor-b) in cardiac muscle-cell hypertrophy

Motoaki Sano, Maha Abdellatif, Hidemasa Oh, Min Xie, Luigi Bagella, Antonio Giordano, Lloyd H. Michael, Francesco J. DeMayo, Michael D. Schneider

Research output: Contribution to journalArticlepeer-review

206 Citations (Scopus)


Hypertrophic growth is a risk factor for mortality in heart diseases. Mechanisms are lacking for this global increase in RNA and protein per cell, which underlies hypertrophy. Hypertrophic signals cause phosphorylation of the RNA polymerase II C-terminal domain, required for transcript elongation. RNA polymerase II kinases include cyclin-dependent kinases-7 (Cdk7) and Cdk9, components of two basal transcription factors. We report activation of Cdk7 and -9 in hypertrophy triggered by signaling proteins (Gαq, calcineurin) or chronic mechanical stress. Only Cdk9 was activated by acute load or, in culture, by endothelin. A preferential role for Cdk9 was shown in RNA polymerase II phosphorylation and growth induced by endothelin, using pharmacological and dominant-negative inhibitors. All four hypertrophic signals dissociated 7SK small nuclear RNA, an endogenous inhibitor, from cyclin T-Cdk9. Cdk9 was limiting for cardiac growth, shown by suppressing its inhibitor (7SK) in culture and preventing downregulation of its activator (cyclin T1) in mouse myocardium.

Original languageEnglish
Pages (from-to)1310-1317
Number of pages8
JournalNature medicine
Issue number11
Publication statusPublished - 2002 Nov 1
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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