Intramyocellular
lipid (IMCL) accumulation in skeletal muscle greatly contributes to
lipid-induced
insulin resistance. Because
acetyl-coenzyme A (
CoA) carboxylase (ACC) 2 negatively modulates mitochondrial
fatty acid oxidation (FAO) in skeletal muscle, ACC2 inhibition is expected to reduce IMCL via elevation of FAO and to attenuate
insulin resistance. However, the concept of substrate competition suggests that enhanced FAO results in reduced
glucose use because of an excessive
acetyl-CoA pool in mitochondria. To identify how ACC2-regulated FAO affects IMCL accumulation and
glucose metabolism, we generated ACC2 knockout (ACC2-/-) mice and investigated skeletal muscle metabolites associated with
fatty acid and
glucose metabolism, as well as whole-body
glucose metabolism. ACC2-/- mice displayed higher capacity of
glucose disposal at the whole-body levels. In skeletal muscle, ACC2-/- mice exhibited enhanced
acylcarnitine formation and reduced IMCL levels without alteration in glycolytic intermediate levels. Notably, these changes were accompanied by decreased
acetyl-CoA content and enhanced mitochondrial pathways related to
acetyl-CoA metabolism, such as the
acetylcarnitine production and tricarboxylic acid cycle. Furthermore, ACC2-/- mice exhibited lower levels of IMCL and
acetyl-CoA even under HFD conditions and showed protection against HFD-induced
insulin resistance. Our findings suggest that ACC2 deletion leads to IMCL reduction without suppressing
glucose use via an elevation in
acetyl-CoA metabolism even under HFD conditions and offer new mechanistic insight into the therapeutic potential of ACC2 inhibition on
insulin resistance.