Chylomicron- and VLDL-derived lipids enter the heart through different pathways: in vivo evidence for receptor- and non-receptor-mediated fatty acid uptake

J Biol Chem. 2010 Dec 3;285(49):37976-86. doi: 10.1074/jbc.M110.174458. Epub 2010 Sep 18.

Abstract

Lipids circulate in the blood in association with plasma lipoproteins and enter the tissues either after hydrolysis or as non-hydrolyzable lipid esters. We studied cardiac lipids, lipoprotein lipid uptake, and gene expression in heart-specific lipoprotein lipase (LpL) knock-out (hLpL0), CD36 knock-out (Cd36(-/-)), and double knock-out (hLpL0/Cd36(-/-)-DKO) mice. Loss of either LpL or CD36 led to a significant reduction in heart total fatty acyl-CoA (control, 99.5 ± 3.8; hLpL0, 36.2 ± 3.5; Cd36(-/-), 57.7 ± 5.5 nmol/g, p < 0.05) and an additive effect was observed in the DKO (20.2 ± 1.4 nmol/g, p < 0.05). Myocardial VLDL-triglyceride (TG) uptake was reduced in the hLpL0 (31 ± 6%) and Cd36(-/-) (47 ± 4%) mice with an additive reduction in the DKO (64 ± 5%) compared with control. However, LpL but not CD36 deficiency decreased VLDL-cholesteryl ester uptake. Endogenously labeled mouse chylomicrons were produced by tamoxifen treatment of β-actin-MerCreMer/LpL(flox/flox) mice. Induced loss of LpL increased TG levels >10-fold and reduced HDL by >50%. After injection of these labeled chylomicrons in the different mice, chylomicron TG uptake was reduced by ∼70% and retinyl ester by ∼50% in hLpL0 hearts. Loss of CD36 did not alter either chylomicron TG or retinyl ester uptake. LpL loss did not affect uptake of remnant lipoproteins from ApoE knock-out mice. Our data are consistent with two pathways for fatty acid uptake; a CD36 process for VLDL-derived fatty acid and a non-CD36 process for chylomicron-derived fatty acid uptake. In addition, our data show that lipolysis is involved in uptake of core lipids from TG-rich lipoproteins.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Hormonal / pharmacokinetics
  • CD36 Antigens / genetics
  • CD36 Antigens / metabolism*
  • Cholesterol, VLDL / genetics
  • Cholesterol, VLDL / metabolism*
  • Chylomicrons / genetics
  • Chylomicrons / metabolism*
  • Fatty Acids / genetics
  • Fatty Acids / metabolism*
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / physiology*
  • Lipoprotein Lipase / genetics
  • Lipoprotein Lipase / metabolism*
  • Lipoproteins, VLDL / genetics
  • Lipoproteins, VLDL / metabolism*
  • Mice
  • Mice, Knockout
  • Myocardium / metabolism*
  • Tamoxifen / pharmacology
  • Triglycerides / genetics
  • Triglycerides / metabolism*

Substances

  • Antineoplastic Agents, Hormonal
  • CD36 Antigens
  • Cholesterol, VLDL
  • Chylomicrons
  • Fatty Acids
  • Lipoproteins, VLDL
  • Triglycerides
  • very low density lipoprotein triglyceride
  • Tamoxifen
  • Lipoprotein Lipase