Reversible phosphorylation of cyclin T1 promotes assembly and stability of P-TEFb
- University of California, San Francisco, United States
Abstract
The positive transcription elongation factor b (P-TEFb) is a critical co-activator for transcription of most cellular and viral genes, including those of HIV. While P-TEFb is regulated by 7SK snRNA in proliferating cells, P-TEFb is absent due to diminished levels of CycT1 in quiescent and terminally differentiated cells, which has remained unexplored. In these cells, we found that CycT1 not bound to CDK9 is rapidly degraded. Moreover, productive CycT1:CDK9 interactions are increased by PKC mediated phosphorylation of CycT1 in human cells. Conversely, dephosphorylation of CycT1 by PP1 reverses this process. Thus, PKC inhibitors or removal of PKC by chronic activation results in P-TEFb disassembly and CycT1 degradation. This finding not only recapitulates P-TEFb depletion in resting CD4+ T cells but also in anergic T cells. Importantly, our studies reveal mechanisms of P-TEFb inactivation underlying T cell quiescence, anergy, and exhaustion as well as proviral latency and terminally differentiated cells.
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Article and author information
Author details
Ignacia Echeverria
Funding
National Institute of Allergy and Infectious Diseases (R01 AI049104)
- Fang Huang
- Daniele C. Cary
- Hana Paculova
- Boris Matija Peterlin
- Koh Fujinaga
National Institute of Allergy and Infectious Diseases (P01 AI091580)
- Trang TT Nguyen
- Arthur Weiss
National Institute of Allergy and Infectious Diseases (P50AI150476)
- Fang Huang
- Ignacia Echeverria
- Rakesh Ramachandran
- Daniele C. Cary
- Hana Paculova
- Andrej Sali
- Boris Matija Peterlin
- Koh Fujinaga
Howard Hughes Medical Institute
- Trang TT Nguyen
- Arthur Weiss
Damon Runyon Cancer Research Foundation
- Trang TT Nguyen
Nora Eccles Treadwell Foundation
- Fang Huang
- Koh Fujinaga
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Huang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Reversible phosphorylation of cyclin T1 promotes assembly and stability of P-TEFb
eLife 10:e68473.
https://doi.org/10.7554/eLife.68473
