Formation of nuclear stress granules involves HSF2 and coincides with the nucleolar localization of Hsp70.

The heat-shock response is characterized by the activation of heat-shock transcription factor 1 (HSF1), followed by increased expression of heat-shock proteins (Hsps). The stress-induced subnuclear compartmentalization of HSF1 into nuclear stress granules has been suggested to be an important control step in the regulation of stress response and cellular homeostasis in human cells. In this study, we demonstrate that the less-well characterized HSF2 interacts physically with HSF1 and is a novel stress-responsive component of the stress granules.

Phosphorylation of serine 303 is a prerequisite for the stress-inducible SUMO modification of heat shock factor 1.

The heat shock response, which is accompanied by a rapid and robust upregulation of heat shock proteins (Hsps), is a highly conserved protection mechanism against protein-damaging stress. Hsp induction is mainly regulated at transcriptional level by stress-inducible heat shock factor 1 (HSF1). Upon activation, HSF1 trimerizes, binds to DNA, concentrates in the nuclear stress granules, and undergoes a marked multisite phosphorylation, which correlates with its transcriptional activity.