AMP-activated protein kinase regulates the expression of monocarboxylate transporter 4 in skeletal muscle.

The aim of this study was to determine the effect of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), an AMP-activated protein kinase (AMPK) activator, on monocarboxylate transporter 4 (MCT4) expression in rat skeletal muscle and a prototypic embryonal rhabdomyosarcoma cell line (RD cells).We examined the alteration in Glucose transporter 4 (GLUT4) and MCT4 mRNA levels by quantitative real-time PCR. Alteration in GLUT4 and MCT4 protein levels was examined by Western blotting.In an in vivo study, AICAR increased MCT4 mRNA and protein levels in a fiber-type specific manner. In an in vitro study, AICAR increased MCT4 mRNA and protein levels. Moreover, AICAR-induced MCT4 expression was blocked by Compound C, an AMPK inhibitor.In this study, we found that AMPK activation induced expression of MCT4 in RD cells and rat skeletal muscle in a fiber-type specific manner. These results indicate the possible involvement of an AMPK-mediated pathway associated with MCT4 expression in skeletal muscle.