Coordination of transcription, RNA processing, and surveillance by P-TEFb kinase on heat shock genes.
Positive transcription elongation factor b (P-TEFb) is a kinase that phosphorylates the carboxyl-terminal domain (CTD) of RNA Polymerase II (Pol II). Here, we show that flavopiridol, a highly specific P-TEFb kinase inhibitor, dramatically reduces the global levels of Ser2--but not Ser5--phosphorylated CTD at actively transcribed loci on Drosophila polytene chromosomes under both normal and heat shocked conditions. Brief treatment of Drosophila cells with flavopiridol leads to a reduction in the accumulation of induced hsp70 and hsp26 RNAs. Surprisingly, the density of transcribing Pol II and Pol II progression through hsp70 in vivo are nearly normal in flavopiridol-treated cells. The major defect in expression is at the level of 3' end processing. A similar but more modest 3' processing defect was also observed for hsp26. We propose that P-TEFb phosphorylation of Pol II CTD coordinates transcription elongation with 3' end processing, and failure to do so leads to rapid RNA degradation.
Ni
Zhuoyu
Z
Department of Molecular Biology and Genetics, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA.
Schwartz
Brian E
BE
Werner
Janis
J
Suarez
Jose-Ramon
JR
Lis
John T
JT
D000818:Animals; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008957:Models, Genetic; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D034741:RNA, Small Interfering / Q000378:metabolism; D012694:Serine / Q000187:drug effects; D014158:Transcription, Genetic
D029721:Drosophila Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D010880:Piperidines; D034741:RNA, Small Interfering; D012694:Serine; C077990:alvocidib; D012313:RNA; D042925:Positive Transcriptional Elongation Factor B; D012319:RNA Polymerase II