Natural Resistance of Human Beta Cells toward Nitric Oxide Is Mediated by Heat Shock Protein 70

• Published in: The Journal of biological chemistry Vol. 275; no. 26; pp. 19521 - 19528
• Main Authors: Burkart, Volker, Liu, Hui, Bellmann, Kerstin, Wissing, Dorte, Jäättelä, Marja, Cavallo, Maria G., Pozzilli, Paolo, Briviba, Karlis, Kolb, Hubert
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.06.2000; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Cell Line; Flow Cytometry; Glucose - pharmacology; Hot Temperature; HSP70 Heat-Shock Proteins - metabolism; HSP70 Heat-Shock Proteins - physiology; Humans; Hypoxanthine - pharmacology; Immunity, Innate; Indicators and Reagents - pharmacology; Insulinoma - metabolism; Islets of Langerhans - drug effects; Islets of Langerhans - metabolism; Mice; Nitric Oxide - metabolism; Nitroprusside - pharmacology; Oxygen Consumption - drug effects; Pancreatic Neoplasms - metabolism; Plasmids; Rats; Reactive Oxygen Species - metabolism; RNA, Antisense - metabolism; Time Factors; Transfection; Tumor Cells, Cultured; Xanthine Oxidase - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M002265200

Human beta cells exhibit increased resistance against nitric oxide (NO) radicals as compared with rodent islet cells. Here we tested whether endogenous heat shock protein 70 (hsp70) accounts for the resistance of human cells. Stable transfection of the human beta cell line CM with an antisense hsp70 mRNA-expressing plasmid (ashsp70) caused selective suppression (>95%) of spontaneously expressed hsp70 but not of hsc70 or GRP75 protein. ashsp70 transfection abolished the resistance of CM cells to the NO donors (Z)-1- (2-(2-aminoethyl)-N-(2-ammonioethyl)amino)diazen-1-ium-1,2-diolate and sodium nitroprusside and increased the proportions of necrotic cells 3–5-fold (p < 0.05) and of apoptotic cells about 2-fold (p < 0.01). Re-induction of hsp70 expression by heat shock re-established resistance to NO toxicity. hsp70 did not exert its protective effect at the level of membrane lipid integrity because radical induced lipid peroxidation appeared independent of hsp70 expression. However, after NO exposure only hsp70-deficient cells showed significantly decreased mitochondrial activity, by 40–80% (p < 0.01). These results suggest a key role of hsp70 in the natural resistance of human beta cells against NO induced injury, by preserving mitochondrial function. These findings provide important implications for the development of beta cell protective strategies in type 1 diabetes and islet transplantation.