Insulin regulates adipocyte lipolysis via an Akt-independent signaling pathway

SM Choi, DF Tucker, DN Gross, RM Easton… - … and cellular biology, 2010 - Taylor & Francis
SM Choi, DF Tucker, DN Gross, RM Easton, LM DiPilato, AS Dean, BR Monks, MJ Birnbaum
Molecular and cellular biology, 2010Taylor & Francis
After a meal, insulin suppresses lipolysis through the activation of its downstream kinase,
Akt, resulting in the inhibition of protein kinase A (PKA), the main positive effector of lipolysis.
During insulin resistance, this process is ineffective, leading to a characteristic dyslipidemia
and the worsening of impaired insulin action and obesity. Here, we describe a noncanonical
Akt-independent, phosphoinositide-3 kinase (PI3K)-dependent pathway that regulates
adipocyte lipolysis using restricted subcellular signaling. This pathway selectively alters the …
After a meal, insulin suppresses lipolysis through the activation of its downstream kinase, Akt, resulting in the inhibition of protein kinase A (PKA), the main positive effector of lipolysis. During insulin resistance, this process is ineffective, leading to a characteristic dyslipidemia and the worsening of impaired insulin action and obesity. Here, we describe a noncanonical Akt-independent, phosphoinositide-3 kinase (PI3K)-dependent pathway that regulates adipocyte lipolysis using restricted subcellular signaling. This pathway selectively alters the PKA phosphorylation of its major lipid droplet-associated substrate, perilipin. In contrast, the phosphorylation of another PKA substrate, hormone-sensitive lipase (HSL), remains Akt dependent. Furthermore, insulin regulates total PKA activity in an Akt-dependent manner. These findings indicate that localized changes in insulin action are responsible for the differential phosphorylation of PKA substrates. Thus, we identify a pathway by which insulin regulates lipolysis through the spatially compartmentalized modulation of PKA.
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