摘要：The expression of hsp 27 mRNA and protein was determined in cultured human proximal tubule (HPT) cells exposed to lethal and sublethal concentrations of Cd2+ under both acute and extended conditions. Initial procedures demonstrated that HPT cells display the classic stress response following physical and chemical stress. Heat stress (42.5 degrees C for 1 hr) caused an increase in both hsp 27 mRNA and protein as well as a shift in the protein to a more phosphorylated state. Results were similar when the cells were subjected to chemical stress (exposure to 100 microM sodium arsenite for 4 hr). Acute exposure to 53 microM CdCl2 for 4 hr also resulted in an increase in hsp 27 mRNA and protein and a shift to the more phosphorylated protein isoform. Extended Cd2+ exposure involved continuous treatment with Cd2+ at both lethal and sublethal levels over a 16-day time course. The results of this treatment showed that chronic exposure to Cd2+ failed to increase either hsp 27 mRNA or protein expression in HPT cells, even at lethal Cd2+ concentrations. In fact, hsp 27 protein levels decreased as compared to controls at both lethal and sub-lethal exposure to Cd2+. These findings imply that hsp 27 expression in human proximal tubule cells may have two distinct modes depending on the nature (acute vs. chronic) of the stress. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (3.5M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 545 546 547 548 549 550 551 552
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