Heat-shock factor proteins

HSF heat shock factor protein MERRF myoclonus epilepsy with ragged red fibers... 

Sorger, P.K. Pelham, H.B.R. (1988). Yeast heat shock factor is an essential DNA binding protein that exhibits temperature-dependent phosphorylation. Cell 54, 855-864. 

TF transcription factor, R receptor, Fur ferric uptake regulation protein, NF-kB nuclear factor-kB, AP-1 activator protein-1, Egr-1 early growth response-1, VDR la,25-dihydroxy-vitamin D3 receptor, RXR retinoid X receptor, PPARy peroxisome proliferator-activated receptor y NFAT nuclear factor of activated T-cells, HSF heat shock factor, p53 tumor suppressor p53, HIF-1 hypoxia inducible factor-1. ... 

Figure 2.2 Proposed mechanism of inducible gene expression mediated by heat shock and certain other pathophysiological conditions. Adapted from Zou et al. (1998). Terminology HSF1 (heat shock factor 1) HSP (heat shock proteins) HSE (heat shock element in DNA) P (phosphorylation).

Cellular control of HSP expression All HSPs are regulated by a small family of transcription factors called heat shock factor (HSFl ). During a stress condition, HSFl and 2 are hyperphosphorylated in a ras-dependent manner by MAP kinases. Binding of these active HSFl factors to DNA sequences called heat shock elements in the promoters of all stress-inducible genes occurs. This leads to increased transcription of HSP genes and induction of HSP proteins. 

Heat shock factor- Heat shock proteins... 

A. A. Knowlton and L. Sun, Heat shock factor-1, steroid hormones, and regulation of heat shock protein expression in the heart, Am. J. Physiol. 280(1), H455-H464 (2001). 

Christians ES, Yan LJ, Benjamin IJ. 2002. Heat shock factor 1 and heat shock proteins Critical partners in protection against acute cell injury. Crit Care Med 30 S43-S50. 

Heat shock transcription factor (HSF) is part of the family of heat shock factors that are activated and bind to DNA induced by OS. Several chemicals, heat shock, or conditions that generate abnormally folded proteins activate HSFl conversion from a monomer to a trimer state (Liu et al., 1996). lodoacetamide (IDAM), an alkylating agent, activates the transcription of Hsp 70 gene (Liu et al., 1996). The depletion of GSH induces oxidation of protein thiols, denaturation, and aggregation of proteins (Freeman et al., 1997). Alkylating agents that deplete GSH increase HSFl (Liu et al., 1996) and induce trimerization of HSFl. 

Liu, H., Lightfoot, R., and Stevens, J.L. (1996). Activation of heat shock factor by alkylating agents is triggered by glutathione depletion and oxidation of protein thiols. J Biol Chem 271, 4805-12. 

Key Words Abiotic stress acquired tolerance antioxidant breeding crop plants cross protection functional genomics heat shock heat shock factors heat shock proteins hydrogen peroxide oxidative stress reactive oxygen species signaling pathways stress tolerance transgenic plants. 

Lee, J.H., A. Hiibel, and E. Schoffl. 1995. Derepression of the activity of genetically engineered heat shock factor causes constitutive synthesis of heat shock proteins and increased thermotolerance in transgenic Arabidopsis. Plant J. 8 603-612. 

Gajone, F., Salina, M., BeneUi-Zazzera, A. 4-hydroxynonenal induces a DNA-binding protein similar to the heat-shock factor. Biochem. J. 1989,262, 977-9. 

Hansen, R.K. et al.. Quercetin inhibits heat shock protein induction but not heat shock factor... 

Jacobs, A.T., and Mamett, L.J. 2007. Heat shock factor 1 attenuates 4-Hydroxynonenal-mediated apoptosis Critical role for heat shock protein 70 induction and stabihzation of Bcl-XL. J. Biol. Cfumt. 282, 33412-33420. 

For many small-scale studies, it is unnecessary to purify a DNA-binding factor to complete homogeneity. Instead, over a hundred-fold enrichment of the factor can be achieved by chromatography of one or several ml of a crude nuclear extract directly on a <1 ml affinity column. Conversely, the flow-through from the column is a specific depletion of the DNA-binding factor from the extract. An example of such an enrichment of heat shock activator protein is shown in Figure 3. 

The enhanced expression of metal-induced stress proteins is controlled primarily at the transcriptional level similar to the induction of hsps by heat (Wu et al. 1986). Regulation of hsp genes in eukaryotic systems is mediated by a cw-acting heat shock control element (HSE) that is found in multiple copies upstream of the transcriptional start site (Pelham 1982). Transcriptional activation of the hsp genes is mediated by a ran -acting protein, known as the heat shock factor (HSF), which binds specifically to the HSE (Wu 1984a,b). 

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