In Vivo, Fatty Acid Translocase (CD36) Critically Regulates Skeletal Muscle Fuel Selection, Exercise Performance, and Training-induced Adaptation of Fatty Acid Oxidation

Jay T. McFarlan, Yuko Yoshida, Swati S. Jain, Xioa-Xia Han, Laelie A. Snook, James Lally, Brennan K. Smith, Jan F. C. Glatz, Joost J. F. P. Luiken, Ryan A. Sayer, A. Russell Tupling, Adrian Chabowski, Graham P. Holloway, Arend Bonen*

*Corresponding author for this work

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For similar to 40 years it has been widely accepted that (i) the exercise-induced increase in muscle fatty acid oxidation( FAO) is dependent on the increased delivery of circulating fatty acids, and (ii) exercise training-induced FAO up-regulation is largely attributable to muscle mitochondrial biogenesis. These long standing concepts were developed prior to the recent recognition that fatty acid entry into muscle occurs via a regulatable sarcolemmal CD36-mediated mechanism. We examined the role of CD36 in muscle fuel selection under basal conditions, during a metabolic challenge (exercise), and after exercise training. We also investigated whether CD36 overexpression, independent of mitochondrial changes, mimicked exercise training-induced FAO up-regulation. Under basal conditions CD36-KO versus WT mice displayed reduced fatty acid transport (-21%) and oxidation (-25%), intramuscular lipids (less than or equal to -31%), and hepatic glycogen (-20%); but muscle glycogen, VO2max, and mitochondrial content and enzymes did not differ. In acutely exercised (78% VO2max) CD36-KO mice, fatty acid transport (-41%), oxidation (-37%), and exercise duration (-44%) were reduced, whereas muscle and hepatic glycogen depletions were accelerated by 27-55%, revealing 2-fold greater carbohydrate use. Exercise training increased mtDNA and beta-hydroxyacyl-CoA dehydrogenase similarly in WT and CD36-KO muscles, but FAO was increased only in WT muscle (+90%). Comparable CD36 increases, induced by exercise training (+44%) or by CD36 overexpression (+41%), increased FAO similarly (84-90%), either when mitochondrial biogenesis and FAO enzymes were up-regulated (exercise training) or when these were unaltered(CD36 overexpression). Thus, sarcolemmal CD36 has a key role in muscle fuel selection, exercise performance, and training-induced muscle FAO adaptation, challenging long held views of mechanisms involved in acute and adaptive regulation of muscle FAO.
Original languageEnglish
Pages (from-to)23502-23516
JournalJournal of Biological Chemistry
Issue number28
Publication statusPublished - 6 Jul 2012

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