Increased protein kinase C theta in skeletal muscle of diabetic patients

In this study we have investigated whether protein kinase C (PKC) protein a nd activity are increased in skeletal muscle of human diabetic patients. Th e protein content of different PKC isoforms (beta, theta, epsilon, delta, m u, and zeta) in the particulate fraction was measured, using Western analys is, in human rectus abdominus skeletal muscle from obese (hyperinsulinemic. normoglycemic) and obese diabetic (hyperinsulinemic, hyperglycemic) subjec ts, PKC theta protein content was significantly higher in the particulate f raction of muscle from diabetic patients compared with the nondiabetic cont rols. PKC theta was immunoprecipitated and its activity was measured in mus cle from diabetic and nondiabetic controls. There was a significant increas e in PKC theta activity in muscle from diabetic patients compared with musc le from nondiabetic controls. Therefore, both PKC theta protein content and activity were significantly increased in the particulate fraction in muscl e from diabetic patients, suggesting the involvement of this isoform in dia betes. Most of the PKC a protein was found in the cytosol. There was no cha nge in cytosolic PKC theta protein content in muscle from diabetic patients compared with muscle from nondiabetic controls. Thus, the increase in part iculate-associated PKC theta was likely due to translocation and activation rather than an increase in protein mass. Copyright (C) 2001 by W.B. Saunde rs Company.