HSF1 Protein, Human (His)

HSF1, a stress-responsive and DNA-binding transcription factor, is a central orchestrator of the heat shock response (HSR), leading to the transcriptional activation of a multitude of heat shock proteins (HSPs) crucial for cellular protection against damage. In unstressed conditions, HSF1 resides in a HSP90-containing multichaperone complex, maintaining an inactivated monomeric state. Upon exposure to stress, particularly heat, HSF1 undergoes homotrimerization and activates the transcription of HSP genes by binding to heat shock elements (HSEs) in their promoters. This transition is reversible, and during the recovery phase of the HSR, HSF1 returns to its unactivated form. Beyond transcriptional activation, HSF1 participates in various cellular processes, including chromatin-associated complex formation with TTC5/STRAP and p300/EP300, repression of Ras-induced c-fos gene transcription, regulation of pre-mRNA processing, nuclear export of stress-induced mRNA, and modulation of mitotic progression. Additionally, in the context of microbial infection, HSF1 plays a role in the reactivation of latent human immunodeficiency virus (HIV-1) transcription by binding to the HIV-1 long terminal repeat promoter.