Insulin action results in the increased expression of several genes as well as the decreased expression of others. One consequence of these global gene expression changes is increased fatty acid synthesis due, in part, to the inhibition of expression of which of the following genes?
A) CYP7A1 (cholesterol 7α-hydroxylase)
B) glucokinase
C) liver pyruvate kinase (LPK)
D) PEPCK
E) PDK4 (pyruvate dehydrogenase kinase 4)

Question

Quizplus · Accepted Answer

PDK4 (pyruvate dehydrogenase kinase 4) inhibits pyruvate dehydrogenase, which converts pyruvate to acetyl-CoA. Acetyl-CoA is a precursor for fatty acid synthesis.  The pyruvate dehydrogenase kinases (PDK1-PDK4) regulate the activity of the PDHc. Phosphorylation of the PDHc by PDK4 results in a lower rate of pyruvate oxidation. Reduced pyruvate oxidation lowers the pool of acetyl-CoA which is required as the substrate for fatty acid and cholesterol synthesis. Since insulin action reduces the expression of PDK4 there will be less inhibition of the PDHc and thus, more acetyl-CoA for fatty acid synthesis

Insulin Action Results in the Increased Expression of Several Genes