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Coordination of transcription, RNA processing, and surveillance by P-TEFb kinase on heat shock genes

Zhuoyu Ni1, Brian E Schwartz, Janis Werner

  • 1Department of Molecular Biology and Genetics, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA.

Molecular Cell
|January 21, 2004
PubMed

Insights

Flavopiridol, a P-TEFb kinase inhibitor, reduces RNA Polymerase II CTD Ser2 phosphorylation and 3' end processing in Drosophila. This leads to decreased RNA accumulation, suggesting P-TEFb coordinates transcription with RNA processing.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Positive transcription elongation factor b (P-TEFb) is a crucial kinase.
  • It phosphorylates the carboxyl-terminal domain (CTD) of RNA Polymerase II (Pol II).
  • This phosphorylation is vital for gene expression regulation.

Purpose of the Study:

  • To investigate the role of P-TEFb in transcription elongation and RNA processing.
  • To determine the effects of P-TEFb inhibition on gene expression in Drosophila.
  • To elucidate the coordination between transcription and 3' end processing.

Main Methods:

  • Utilized flavopiridol, a specific P-TEFb kinase inhibitor.
  • Examined Drosophila polytene chromosomes and cultured Drosophila cells.
  • Analyzed RNA Polymerase II CTD phosphorylation (Ser2 and Ser5) and RNA accumulation (hsp70, hsp26).

Main Results:

  • Flavopiridol significantly reduced global Ser2-phosphorylated CTD levels.
  • Accumulation of hsp70 and hsp26 RNAs decreased after flavopiridol treatment.
  • Despite normal Pol II density and progression, a major defect in 3' end processing was observed.

Conclusions:

  • P-TEFb phosphorylation of Pol II CTD is essential for coordinating transcription elongation with 3' end processing.
  • Inhibition of P-TEFb leads to impaired RNA processing and subsequent RNA degradation.
  • This highlights a critical regulatory link between transcription and RNA processing for gene expression.

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