Hsf1 (human, recombinant)

Heat-shock factor 1 (Hsf1) is a transcription factor involved in the heat-shock response.¹ It is composed of an N-terminal DNA-binding domain, a hydrophobic repeat region (HR-A/B), which mediates oligomerization required for DNA binding, a D domain, a regulatory domain, a repeat region (HR-C), which prevents oligomerization by binding to HR-A/B in its inactive form, and a C-terminal transactivation domain.^2,1,3 When inactive, Hsf1 is monomeric and bound to heat shock proteins (HSPs) but, upon induction of the heat-shock response, it forms homotrimers, is translocated to the nucleus, and binds to heat-shock elements (HSEs) in the promotor region of target genes, such as HSPs.¹ Hsf1 is ubiquitously expressed and activated by heat shock, as well as a variety of other factors, including inflammation, ischemia, infection, and aging.^4,1 It is involved in transactivation of genes involved in these processes, as well as genes involved in development, metabolism, and carcinogenesis.⁴ Hsf1 is constitutively active in certain cancers and its deficiency in rodent models is associated with a reduction in tumor formation.^4,3 Protein levels of Hsf1 are increased in breast cancer tumors and this overexpression, as well as nuclear localization of Hsf1, is associated with reduced survival.³ Cayman’s Hsf1 (human, recombinant) protein was synthesized from a DNA sequence encoding the mature form of species protein (Asp2-Ser529) with an N-terminal translation-initiating methionine (Met1). The expressed protein consists of 539 amino acids, has a calculated molecular weight of 58.6 kDa, and a predicted N-terminus of Met1. By SDS-PAGE, under reducing conditions, the apparent molecular mass of the protein is approximately 67 kDa potentially due to post-translational modifications or other experimental conditions.

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1. Ramos, C.H.I., and Quel, N.G. Heat Shock Factor (HSF): The promoter of chaperone genes. A mini review. Curr. Proteomics 15(1), (2018).

2. Vihervaara, A., and Sistonen, L. HSF1 at a glance. J. Cell Sci. 127(Pt 2), 261-266 (2014).

3. Yan, P., Guzman, M.L., Peter, R.I., et al. HSF1 and molecular chaperones in biology and cancer. (2020).

4. Li, J., Labbadia, J., and Morimoto, R.I. Rethinking HSF1 in stress, development and organismal health. Trends Cell Biol. 27(12), 895-905 (2017).