Figure 5.

Impairment of the proteasome activity leads to an HDAC6-dependent activation of HSF1. Human HEK KD (HDAC6 knockdown) and control cells were treated with an anti-PAC1 siRNA for the indicated periods of time, and the accumulation of polyubiquitinated proteins (A) and activation of HSF1 and HSP70 (B) accumulation were monitored. The level of general protein ubiquitination and HSP70 did not change before 30 h of transfection and was comparable with that of nontransfected cells (“0” in A and not shown).