Role of protein kinase C during insulin mediated skeletal muscle cell spreading.

Protein kinase C (PKC) is known to play important roles in integrin mediated cell spreading. This study investigated the role of PKC during insulin mediated muscle cell spreading, which was independent of integrin alpha5. We found that PKC-alpha becomes active and localise to membrane during insulin mediated cell spreading. We also found that PKC activation is essential for cell spreading stimulated by insulin and this activation enhances the cell spreading. PKC activation increased the tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin as well as tyrosine kinase activity of FAK. We also observed that PKC activation enhanced the FAK associated PI 3-kinase activity and also increased the activation of ERK-1/-2. Moreover, the effect of PKC activation on insulin mediated cell spreading as well as tyrosine phosphorylation of FAK and paxillin depends upon integrity of actin cytoskeleton. Thus, PKC is an important signaling protein during insulin mediated muscle cell spreading.