title: Heat shock protein 27 expression in human proximal tubule cells exposed to lethal and sublethal concentrations of CdCl2.
abstract: 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.
authors.affiliation: Robert C. Byrd Health Sciences Center, Department of Pathology, West Virginia University, Morgantown, West Virginia 26506, USA.
authors.forename: S
authors.initials: S
authors.lastname: Somji
authors.forename: D A
authors.initials: DA
authors.lastname: Sens
authors.forename: S H
authors.initials: SH
authors.lastname: Garrett
authors.forename: M A
authors.initials: MA
authors.lastname: Sens
authors.forename: J H
authors.initials: JH
authors.lastname: Todd
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D018053:Arsenites / Q000633:toxicity; D019256:Cadmium Chloride / Q000633:toxicity*; D002478:Cells, Cultured; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation
chemical_list: D018053:Arsenites; D006360:Heat-Shock Proteins; D019256:Cadmium Chloride; C015001:arsenite