Role of small heat shock proteins in muscle under chronic hyperglycemia (1102.42)

Abstract

Role of small heat shock proteins in muscle under chronic hyperglycemia V. Sudhakar Reddy1, G. Bhanuprakash Reddy1 1Department of Biochemistry, National Institute of Nutrition, Hyderabad, India Objective: To study the expression of small heat shock proteins (sHsp) and their localization in diabetic rat muscle.Methods: Diabetes was induced in rats and maintained on hyperglycemia for a period of 12 weeks. The expression of sHsp and phosphorylated sHsp was analysed by qRT‐PCR, immunoblotting. The translocation of phosphorylated sHsp (pS82‐Hsp27, pS59‐αB‐crystallin; αBC) was analyzed by detergent solubility assay and co‐immunoprecipitation. The cell death was analysed by assessing the levels bcl‐2, bax and cleaved caspase‐3. The interaction of αBC with bax was analyzed by co‐immunoprecipitation Results: Out of 10 sHsp, 7 sHsp were detected in muscle. Among them, increased expression of αBC was seen diabetic muscle. Furthermore, detergent soluble assay and co‐immunoprecipitation studies confirmed the translocation and interaction of phosphorylated sHsp with cytoskeleton (desmin) under diabetic conditions. Diabetes induced the cell death as assessed by the levels of cleaved caspase‐3, bax and bcl‐2. Moreover, diabetes reduced the interaction of αBC with bax.Conclusion: There was increased expression of αBC under hyperglycemic conditions. Further, chronic hyperglycemia induced the translocation of pS82‐Hsp27 and pS59‐αBC from cytoplasm to a striated sarcomere at or near z‐lines and intercalated discs. Altered interaction of αBC with bax seems to influence cell death in diabetic muscle.