This proposal focuses on the role of atypical PKCs, PKC-zetu and PKC-lambda during insulin stimulation of glucose transport in skeletal muscle preparations of rodents and humans. Previous work strongly suggests that both atypical PKCs, rather than diacyglycerol-sensitive PKCs, serve as a downstream effector of PI 3-kinase during insulin action in rat adipocytes, 3T3/L1 adipocytes and L6 myotubes. Moreover, both PKC-zetu and PKC- lambda appear to be required for insulin stimulation of GLUT 4 translocation and glucose transport in these cells. Insulin pilot studies suggest that insulin activates PKC-zetu/lambda in rat skeletal muscles, but these studies need to be expanded to examine the rapidity and duration of this activation in specific muscles and the involvement of either or both atypical PKCs in this activation. After examining the activation of PKC-zetu/lambda in normal rodents, we will examine this activation on skeletal muscles of rodents that have clinical forms of insulin resistance, i.e., GK rats, Zucker rats, obese-aged rats, ob/ob mice and db/db mice to see if there are defects in signaling that involve PKC-zetu and/or PKC-lambda that could be important in examining defects observed in skeletal muscles or other tissues (e.g., adipocytes) of these rodents. Finally, we will examine the activation and levels of PKC-zetu and PKC-lambda on skeletal muscles and adipose tissue obtained from normal, obese, diabetic and obese-diabetic humans, using abdominal wall tissues obtained during non-emergent abdominal lapartomies. Our studies should provide initial insights into the importance of PKC-zetu and/or PKC-lambda during insulin action in skeletal muscles of normal and insulin-resistant rodents and humans.
