Document Detail

Modulation of a P-TEFb functional equilibrium for the global control of cell growth and differentiation.
MedLine Citation:
PMID:  16980611     Owner:  NLM     Status:  MEDLINE    
P-TEFb phosphorylates RNA polymerase II and negative elongation factors to stimulate general transcriptional elongation. It is kept in a functional equilibrium through alternately interacting with its positive (the Brd4 protein) and negative (the HEXIM1 protein and 7SK snRNA) regulators. To investigate the physiological significance of this phenomenon, we analyzed the responses of HeLa cells and murine erythroleukemia cells (MELC) to hexamethylene bisacetamide (HMBA), which inhibits growth and induces differentiation of many cell types. For both cell types, an efficient, albeit temporary disruption of the 7SK-HEXIM1-P-TEFb snRNP and enhanced formation of the Brd4-P-TEFb complex occurred soon after the treatment started. When the P-TEFb-dependent HEXIM1 expression markedly increased as the treatment continued, the abundant HEXIM1 pushed the P-TEFb equilibrium back toward the 7SK/HEXIM1-bound state. For HeLa cells, as HMBA produced only a minor, temporary effect on their growth, the equilibrium gradually returned to its pretreatment level. In contrast, long-term treatment of MELC induced terminal division and differentiation. Concurrently, the P-TEFb equilibrium was shifted overwhelmingly toward the 7SK snRNP side. Together, these data link the P-TEFb equilibrium to the intracellular transcriptional demand and proliferative/differentiated states of cells.
Nanhai He; Andrea C Pezda; Qiang Zhou
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular and cellular biology     Volume:  26     ISSN:  0270-7306     ISO Abbreviation:  Mol. Cell. Biol.     Publication Date:  2006 Oct 
Date Detail:
Created Date:  2006-09-18     Completed Date:  2006-10-24     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8109087     Medline TA:  Mol Cell Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7068-76     Citation Subset:  IM    
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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MeSH Terms
Acetamides / pharmacology
Cell Differentiation / drug effects,  physiology*
Cell Growth Processes / drug effects,  physiology
Chromatin / metabolism
HIV-1 / genetics
Hela Cells
Positive Transcriptional Elongation Factor B / metabolism*
Protein Binding / drug effects
RNA-Binding Proteins / metabolism
Ribonucleoproteins, Small Nuclear / metabolism
Transcription, Genetic / drug effects
Grant Support
Reg. No./Substance:
0/Acetamides; 0/Chromatin; 0/HEXIM1 protein, human; 0/RNA-Binding Proteins; 0/Ribonucleoproteins, Small Nuclear; 3073-59-4/hexamethylene bisacetamide; EC 2.7.11.-/Positive Transcriptional Elongation Factor B

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