P-TEFb kinase recruitment and function at heat shock loci

Citation
Jt. Lis et al., P-TEFb kinase recruitment and function at heat shock loci, GENE DEV, 14(7), 2000, pp. 792-803
Citations number
60
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
GENES & DEVELOPMENT
ISSN journal
0890-9369 → ACNP
Volume
14
Issue
7
Year of publication
2000
Pages
792 - 803
Database
ISI
SICI code
0890-9369(20000401)14:7<792:PKRAFA>2.0.ZU;2-H
Abstract
P-TEFb, a heterodimer of the kinase Cdk9 and cyclin T, was isolated as a fa ctor that stimulates formation of productive transcription elongation compl exes in vitro. Here, we show that P-TEFb is located at >200 distinct sites on Drosophila polytene chromosomes. Upon heat shock, P-TEFb, like the regul atory factor HSF, is rapidly recruited to heat shock loci, and this recruit ment is blocked in an HSF mutant. Yet, HSF binding to DNA is not sufficient to recruit P-TEFb, in vivo, and HSF and P-TEFb immunostainings within a he at shock locus are not coincident. Insight to the function of P-TEFb is off ered by experiments showing that the direct recruitment of a Gal4-binding d omain P-TEPb hybrid to an hsp70 promoter in Drosophila cells is sufficient to activate transcription in the absence of heat shock. Analyses of point m utants show this P-TEFb stimulation is dependent on Cdk9 kinase activity an d on Cdk9's interaction with cyclin T. These results, coupled with the freq uent colocalization of P-TEFb and the hypophosphorylated form of RNA polyme rase II (Pol II) found at promoter-pause sites, support a model in which P- TEFb acts to stimulate promoter-paused pol II to enter into productive elon gation.