Examination of HSF1 and HSF2: A Functional Domain Analysis
Ksar, Jamal S.
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Human cells are constantly being exposed to adverse conditions. The adverse conditions can arise from being exposed to extreme temperatures, various diseases, aging and many other circumstances. These circumstances can be deleterious to the cell because they cause proteins to unfold, misfold and aggregate. This leads to malfunctional proteins and toxic levels of nonnative proteins in the cell. Consequently, the cell requires a mechanism to respond to the negative conditions and prevent cellular damage that may be caused. This mechanism is described as the heat shock response. It is comprised of HSF's that serve to activate heat shock proteins. Once activated heat shock proteins can prevent cellular damage caused by extreme conditions. This mechanism of activation is very important because of its critical role in the life and death of cells. This particular study seeks to further characterize the domains of the proteins HSFI and HSF2. This was accomplished by creating fluorescently labeled chimeric fusions of the two HSF's. Their differential behavior under normal conditions and heat shock conditions was used as the criteria for comparison of chimeras. HSF1 in located nuclearly under normal conditions and forms nuclear granules upon heat shock. HSF2 is located in the cytoplasm and nucleus under normal conditions and locates perinuclearly upon heat shock indicating its inactivation. Based on these characteristic behaviors, the study suggested that hydrophobic region C may play a critical role in the granule formation of HSF1 and the inactivation and perinuclear localization of HSF2.