Biochemical and Biophysical Research Communications, Vol.368, No.3, 716-722, 2008
Glucose deprivation accelerates VLDL receptor-mediated TG-rich lipoprotein uptake by AMPK activation in skeletal muscle cells
Glucose and fatty acids are major energy sources in skeletal muscle. Very low-density lipoprotein receptor (VLDL-R), which is highly expressed in heart, skeletal muscle and adipose tissue, plays a crucial role in metabolism of triglyceride (TG)-rich lipoproteins. To explore energy switching between glucose and fatty acids, we studied expression of VLDL-R and lipoprotein uptake in rat L6 myoblasts. L-Glucose or D-glucose deprivation in the medium noticeably induced the AMPK (AMP-activated protein kinase) activation and VLDL-R expression. Dose-dependent induction of VLDL-R expression was observed when D-glucose was less than 4.2 mM. The same phenomenon was also observed in rat primary skeletal myoblasts and cultured vascular smooth muscle cells. The uptake of P-VLDL but not LDL was accompanied by induction of VLDL-R expression. Our study suggests that the VLDL-R-mediated uptake of TG-rich lipoproteins might compensate for glucose shortfall through AMPK activation in skeletal muscle. (c) 2008 Elsevier Inc. All rights reserved.
Keywords:energy switching;fatty acid metabolism;glucose metabolism;lipoprotein metabolism;skeletal muscle;VLDL receptor;AMP-activated protein kinase (AMPK);metformin