title: Enhanced HSP30 and HSP70 accumulation in Xenopus cells subjected to concurrent sodium arsenite and cadmium chloride stress.
abstract: Heat shock proteins (HSPs) are molecular chaperones that aid in protein folding, translocation and in preventing stress-induced protein aggregation. The present study examined the effect of simultaneous sodium arsenite and cadmium chloride treatment on the pattern of HSP30 and HSP70 accumulation in A6 kidney epithelial cells of the frog, Xenopus laevis. Immunoblot analysis revealed that HSP30 and HSP70 accumulation in concurrent stressor treatments were significantly higher than the sum of HSP30 or HSP70 accumulation in individual treatments. This finding suggested a synergistic action between sodium arsenite and cadmium chloride. KNK437 inhibitor studies indicated that the combined stressor-induced accumulation of HSPs may be regulated, at least in part, at the level of transcription. Immunocytochemistry revealed that simultaneous treatment of cells with the two stressors induced HSP30 accumulation primarily in the cytoplasm in a punctate pattern with some dysregulation of F-actin structure. Increased ubiquitinated protein accumulation was observed with combined sodium arsenite and cadmium chloride treatment compared to individual stressors suggesting an impairment of the ubiquitin proteasome degradation system. The addition of a mild heat shock further enhanced the accumulation of HSP30 and HSP70 in response to relatively low concentrations of sodium arsenite plus cadmium chloride.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
authors.forename: Imran
authors.initials: I
authors.lastname: Khamis
authors.forename: John J
authors.initials: JJ
authors.lastname: Heikkila
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D018053:Arsenites / Q000633:toxicity*; D001559:Benzhydryl Compounds / Q000494:pharmacology; D019256:Cadmium Chloride / Q000633:toxicity*; D004357:Drug Synergism; D050890:HSP30 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D011760:Pyrrolidinones / Q000494:pharmacology; D017670:Sodium Compounds / Q000633:toxicity*; D054875:Ubiquitination / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D000199:Actins; D018053:Arsenites; D001559:Benzhydryl Compounds; D050890:HSP30 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C410027:KNK 437; D011760:Pyrrolidinones; D017670:Sodium Compounds; D014874:Water Pollutants, Chemical; D029867:Xenopus Proteins; C017947:sodium arsenite; D019256:Cadmium Chloride
keywords: Amphibian; Cadmium chloride; Confocal microscopy; Heat shock proteins; Molecular chaperone; Sodium arsenite