title: High density lipoprotein (HDL) promotes glucose uptake in adipocytes and glycogen synthesis in muscle cells.
abstract: BACKGROUND
  High density lipoprotein (HDL) was reported to decrease plasma glucose and promote insulin secretion in type 2 diabetes patients. This investigation was designed to determine the effects and mechanisms of HDL on glucose uptake in adipocytes and glycogen synthesis in muscle cells.
  
  
  RESULTS
  Actions of HDL on glucose uptake and GLUT4 translocation were assessed with 1-[(3)H]-2-deoxyglucose and plasma membrane lawn, respectively, in 3T3-L1 adipocytes. Glycogen analysis was performed with amyloglucosidase and glucose oxidase-peroxidase methods in normal and palmitate-treated L6 cells. Small interfering RNA was used to observe role of scavenger receptor type I (SR-BI) in glucose uptake of HDL. Corresponding signaling molecules were detected by immunoblotting. HDL stimulated glucose uptake in a time- and concentration-dependent manner in 3T3-L1 adipocytes. GLUT4 translocation was significantly increased by HDL. Glycogen deposition got enhanced in L6 muscle cells paralleling with elevated glycogen synthase kinase3 (GSK3) phosphorylation. Meanwhile, increased phosphorylations of Akt-Ser473 and AMP activated protein kinase (AMPK) α were detected in 3T3-L1 adipocytes. Glucose uptake and Akt-Ser473 activation but not AMPK-α were diminished in SR-BI knock-down 3T3-L1 cells.
  
  
  CONCLUSIONS
  HDL stimulates glucose uptake in 3T3-L1 adipocytes through enhancing GLUT4 translocation by mechanisms involving PI3K/Akt via SR-BI and AMPK signaling pathways, and increases glycogen deposition in L6 muscle cells through promoting GSK3 phosphorylation.
authors: Jiangsu Provincial Key Lab of Cardiovascular Diseases and Molecular Intervention, Department of Pharmacology, Nanjing Medical University, Nanjing, People's Republic of China.
authors: Qichun
authors: Q
authors: Zhang
authors: Yun
authors: Y
authors: Zhang
authors: Haihua
authors: H
authors: Feng
authors: Rui
authors: R
authors: Guo
authors: Lai
authors: L
authors: Jin
authors: Rong
authors: R
authors: Wan
authors: Lina
authors: L
authors: Wang
authors: Cheng
authors: C
authors: Chen
authors: Shengnan
authors: S
authors: Li
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D018955:CD36 Antigens / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D005089:Exocytosis / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis*; D008075:Lipoproteins, HDL / Q000494:pharmacology*; D051379:Mice; D032342:Muscle Cells / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats
chemical_list: D018955:CD36 Antigens; D051275:Glucose Transporter Type 4; D008075:Lipoproteins, HDL; D006003:Glycogen; D005947:Glucose