Protein kinase C is not required for insulin stimulation of hexose uptake in muscle cells in culture.
The L6 skeletal muscle cell line has been identified as a suitable model to study the action of insulin on glucose uptake in muscle [Klip, Li & Logan (1984) Am. J. Physiol. 247, E291-E296]. The signals that transfer information from occupied insulin receptors to glucose transporters remain unknown. Here we report that activation of protein kinase C by exogenous phorbol esters results in stimulation of glucose uptake. Protein C kinase activity was induced to migrate from the cytosolic fraction to the microsomal fraction after 40 min of exposure of intact cells to 4 beta-phorbol 12,13-dibutyrate. In contrast, incubation with insulin did not alter the subcellular distribution of the kinase. Prolonged preincubation of L6 cells with phorbol esters resulted in depletion of kinase C activity, whereas neither the basal rate of glucose uptake nor its stimulation by insulin were affected. This suggests that protein kinase C is expressed in L6 cells, and that insulin stimulation of hexose transport does not involve protein kinase C.
Klip
A
A
Ramlal
T
T
D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D006601:Hexoses / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D009132:Muscles / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology
D006601:Hexoses; D007328:Insulin; D010703:Phorbol Esters; D011493:Protein Kinase C