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Edited by Miguel De la RosaKeywords: Molecular chaperone Heat-shock protein with subunit molecular masses of 70 kDa Antibiotics Gentamicin a b s t r a c tWe previously reported that gentamicin (GM) specifically binds to heat-shock protein with subunit molecular masses of 70 kDa (HSP70). In the present study, we have investigated the effects of GM binding on HSP70-assisted protein folding in vitro. The C-terminal, and not the N-terminal of HSP70 was found to bind to GM. GM significantly suppressed refolding of firefly luciferase in the presence of HSP70 and HSP40, although the ATPase activity of HSP70 was unaffected by GM. A surface plasmon resonance analysis revealed that GM specifically interferes with the binding of HSP70 to a model peptide that mimics the exposed hydrophobic surface of the folding intermediates. These results indicated that GM inhibits the chaperone activity of HSP70 and may suppress protein folding via inhibition of HSP70 in vivo.

This review will focus on gastrointestinal mucosal protection against cytotoxic agents and cellular stress mainly from the viewpoint of expression and function of heat shock proteins, in their role of 'molecular chaperones', as internal cytoprotectants. Also, recently identified target molecules of heat shock protein in damaged gastric mucosal cells are introduced. Elucidation of such stress-responses and repairing process of damaged protein by heat shock proteins in the gastrointestinal mucosa may provide a better understanding for the mechanisms of cytoprotection and cellular repair. In addition, these findings in post-genomic level may provide new strategies for the therapy of gastrointestinal disorders.

Our results suggest that HSP90 might play an important role in protecting small intestinal epithelial cells from hydrogen peroxide-induced or indomethacin-induced cell injury in vitro, and raised the possibility of protection of small intestinal epithelial cells by manipulation of HSP90 expression.

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