Antigen: purified recombinant Hsf1 protein · Clone designation: 10H8 · Host: rat · Isotype: IgG₁ · Application(s): WB. IP, ICC, and EIA · Heat shock factor 1 (Hsf1) belongs to a family of heat shock transcription factors that activate the transcription of genes encoding products required for protein folding, processing, targeting, degradation, and function.¹ The up-regulation of Hsp expression by stressors is achieved at the level of transcription through a heat shock element (HSE) and a transcription factor.^2,3,4 Most Hsfs have highly conserved amino acid sequences. On all Hsfs there is a DNA binding domain at the N-terminus. Hydrophobic repeats located adjacent to this binding domain are essential for the formation of active trimers. Towards the C-terminal region another short hydrophobic repeat exists and is thought to be necessary for suppression of trimerization.⁵ There are two main Hsfs, 1 and 2. Murine Hsf1 exists as two isoforms, however in higher eukaryotes Hsf1 is found in a diffuse cytoplasmic and nuclear distribution in unstressed cells. Once exposed to a multitude of stressors, it localizes to discrete nuclear granules within seconds. As it recovers from stress, Hsf1 dissipates from these granules to a diffuse nucleoplasmic distribution. Hsf2 on the other hand is similar to murine Hsf1, as it exists as two isoforms, the α form being more transcriptionally active than the smaller β form.^6,7 Various experiments have suggested that Hsf2 may have roles in differentiation and development.^8,9,10

1 Morano, K.A., and Thiele, D.J. Heat shock factor function and regulation in response to cellular stress, growth, and differentiation signals. Gene Expr 7 271-282 (1998).

2 Tanaka, K., Namba, T., Arai, Y., et al. Genetic evidence for a protective role for heat shock factor 1 and heat shock protein 70 against colitis. J Biol Chem (2007).

3 Morimoto, R.I. Regulation of the heat shock transcriptional response: Cross talk between a family of heat shock factors, molecular chaperones, and negative regulators. Genes Dev 12 3788-3796 (1998).

4 McMillan, D.R., Xiao, X., Shao, L., et al. Targeted disruption of heat shock transcription factor 1 abolishes thermotolerance and protection against heat-inducible apoptosis. J Biol Chem 273(13) 7523-7528 (1998).

5 Jolly, C., Usson, Y., and Morimoto, R.I. Rapid and reversible relocalization of heat shock factor 1 within seconds to nuclear stress granules. Proc Natl Acad Sci USA 96 6769-6774 (1999).

6 Fiorenza, M.T., Farkas, T., Dissing, M., et al. Complex expression of murine heat shock transcription factors. Nucleic Acids Res 23(3) 467-474 (1995).

7 Goodson, M.L., Park-Sarge, O., and Sarge, K.D. Tissue-dependent expression of heat shock factor 2 isoforms with distinct transcriptional activites. Mol Cell Biol 15(10) 5288-5293 (1995).

8 Rallu, M., Loones, M., Lallemand, Y., et al. Function and regulation of heat shock factor 2 during mouse embryogenesis. Proc Natl Acad Sci USA 94 2392-2397 (1997).

9 Sarge, K.D., Park-Sarge, O., Kirby, J.D., et al. Expression of heat shock factor 2 in mouse testis: Potential role as a regulator of heat-shock protein gene expression during spermatogenesis. Biol Reprod 50 1334-1343 (1994).

10 Murphy, S.P., Gorzowski, J.J., Sarge, K.D., et al. Characterization of constitutive HSF2 DNA-binding activity in mouse embryonal carcinoma cells. Mol Cell Biol 14(8) 5309-5317 (1994).

Cotto, J.J., Fox, S.G., and Morimoto, R.I. HSF1 granules: A novel stress-induced nuclear compartment of human cells. J Cell Sci 110 2925-2934 (1997).

Morimoto, R.I. Regulation of the heat shock transcriptional response: Cross talk between a family of heat shock factors, molecular chaperones, and negative regulators. Genes Dev 12 3788-3796 (1998).

Jolly, C., Usson, Y., and Morimoto, R.I. Rapid and reversible relocalization of heat shock factor 1 within seconds to nuclear stress granules. Proc Natl Acad Sci USA 96 6769-6774 (1999).

Goodson, M.L., Park-Sarge, O., and Sarge, K.D. Tissue-dependent expression of heat shock factor 2 isoforms with distinct transcriptional activites. Mol Cell Biol 15(10) 5288-5293 (1995).

Sarge, K.D., Park-Sarge, O., Kirby, J.D., et al. Expression of heat shock factor 2 in mouse testis: Potential role as a regulator of heat-shock protein gene expression during spermatogenesis. Biol Reprod 50 1334-1343 (1994).

Rallu, M., Loones, M., Lallemand, Y., et al. Function and regulation of heat shock factor 2 during mouse embryogenesis. Proc Natl Acad Sci USA 94 2392-2397 (1997).

Fiorenza, M.T., Farkas, T., Dissing, M., et al. Complex expression of murine heat shock transcription factors. Nucleic Acids Res 23(3) 467-474 (1995).

McMillan, D.R., Xiao, X., Shao, L., et al. Targeted disruption of heat shock transcription factor 1 abolishes thermotolerance and protection against heat-inducible apoptosis. J Biol Chem 273(13) 7523-7528 (1998).

Tanaka, K., Namba, T., Arai, Y., et al. Genetic evidence for a protective role for heat shock factor 1 and heat shock protein 70 against colitis. J Biol Chem (2007).

Morano, K.A., and Thiele, D.J. Heat shock factor function and regulation in response to cellular stress, growth, and differentiation signals. Gene Expr 7 271-282 (1998).

Murphy, S.P., Gorzowski, J.J., Sarge, K.D., et al. Characterization of constitutive HSF2 DNA-binding activity in mouse embryonal carcinoma cells. Mol Cell Biol 14(8) 5309-5317 (1994).

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