Heat shock

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In biochemistry, heat shock is the effect of subjecting a cell to a higher temperature than that of the ideal body temperature of the organism from which the cell line was derived.

Heat shock response[edit]

The cellular response to heat shock includes the transcriptional up-regulation of genes encoding heat shock proteins (HSPs) as part of the cell's internal repair mechanism.[1] They are also called stress-proteins.[2] and respond to heat, cold and oxygen deprivation by activating several cascade pathways. HSPs are also present in cells under perfectly normal conditions.[2] Some HSPs, called chaperones, ensure that the cell’s proteins are in the right shape and in the right place at the right time.[1][2] For example, HSPs help new or misfolded proteins to fold into their correct three-dimensional conformations, which is essential for their function.[2] They also shuttle proteins from one compartment to another inside the cell, and target old or terminally misfolded proteins to proteases for degradation.[2] Heat shock proteins are also believed to play a role in the presentation of pieces of proteins (or peptides) on the cell surface to help the immune system recognize diseased cells.[3]

The up-regulation of HSPs during heat shock is generally controlled by a single transcription factor; in eukaryotes this regulation is performed by heat shock factor (HSF), while σ32 is the heat shock sigma factor in Escherichia coli.[1]

Inducing heat shock[edit]

In fish that survive at 0°C, heat shock can be induced with temperatures as low as 5°C, whereas thermophilic bacteria that proliferate at 50°C will not express heat shock proteins until temperatures reach approximately 60°C.[4] The process of heat shocking can be done in a CO2 incubator, O2 incubator, or a hot water bath.

See also[edit]

References[edit]

  1. ^ a b c Guisbert, E., Yura, T., Rhodius, V.A., and Gross, C.A. 2008. Convergence of molecular, modeling and systems approaches for an understanding of the Escherichia coli heat shock response. Micro. Mol. Biol. Rev. 72: 545-554. doi:10.1128/MMBR.00007-08
  2. ^ a b c d e Vabulas, R.M,, Raychaudhuri, S., Hayer-Hartl, M. and Hartl, F.U. 2010. Protein Folding in the Cytoplasm and the Heat Shock Response. Cold Spring Harb. Perspect. Biol. doi:10.1101/cshperspect.a004390
  3. ^ Tsan, M. and Gao, B. 2009. Heat shock proteins and immune system. Journal of Leukocyte Biology. 85( 6): 905-910. doi:10.1189/jlb.0109005.
  4. ^ Lindquist, S. and Craig, E.A. 1988. The Heat-Shock Proteins. Annual Review of Genetics. 22: 631-677.[1] doi:10.1146/annurev.ge.22.120188.003215