Regulation of HSF Activation and Repression

Abstract

Heat shock response (HSR) is characterized by robust induction of heat shock proteins (HSPs) during heat shock and is regulated mainly at the level of transcription by heat shock factor (HSF). Preexisting inert HSF monomers undergo conformational change to form trimers that bind to DNA and to acquire transcriptional activity during heat shock and other stimuli. These two steps are separated processes and are induced by release from feedback repression by HSPs, direct effects of stimuli, posttranslational modifications, and others. Basal activity of HSF is also regulated in unstressed conditions. In this chapter, we review molecular mechanisms of activation and repression of HSF and describe stimuli that activate HSF by controlling these mechanisms.