Fig. 3.

Transcription elongation of heat shock genes is regulated by lncRNA. RNA polymerase II (Pol II) pauses following transcription initiation at gene promoters. P-TEFb promotes transcription elongation by phosphorylating (P) heptapeptide repeats at serine-2 within the carboxyl terminal domain (CTD) of Pol II. 7SK is a nuclear lncRNA (∼331 nts) that interacts with a subpopulation of P-TEFb repressing its activity and sequestering its ability to interact with transcription complexes. Induction of the stress response (e.g., heat shock) causes P-TEFb to disassociate from 7SK allowing it to interact with Pol II and promote transcription elongation of susceptible genes including heat shock response factors. By this mechanism, 7SK functions in trans as a scaffold component of P-TEFb and regulator of gene transcription in response to stress signals