Adenosine monophosphate (
AMP)-activated protein kinase (AMPK) plays a crucial role in the maintenance of cellular energy homeostasis, and several natural compounds that activate AMPK possibly enhance
glucose uptake by muscle cells. In this study, we found that
pinusolide stimulated AMPK phosphorylation and
glucose uptake and these effects were significantly reduced by
siRNA LKB1 or compound C, suggesting that enhanced
glucose uptake by
pinusolide is predominantly accomplished via an LKB1-mediated AMPK activation pathway. An
insulin resistance state was induced by exposing cells to 30mM
glucose, as indicated by reduced
insulin-stimulated
tyrosine phosphorylation of IRS-1 and
glucose uptake. Under these conditions, the phosphorylation of AMPK and ACC were decreased. Surprisingly, disrupted
insulin signaling and decreased AMPK activity by high
glucose concentrations were prevented by
pinusolide. Moreover, this treatment increased
insulin-stimulated
glucose uptake via AMPK activation. Taken together, our findings suggest a link between high
glucose and
insulin resistance in muscle cells, and provide further evidence that
pinusolide attenuates blockade of
insulin signaling by enhancing IRS-1
tyrosine phosphorylation by the activating the AMPK pathway. In addition, this study indicates the targeting of AMPK represents a new therapeutic strategy for
hyperglycemia-induced
insulin resistance and
type 2 diabetes.