Capric Acid Up-Regulates UCP3 Expression without PDK4 Induction in Mouse C2C12 Myotubes.
Uncoupling protein 3 (UCP3) and pyruvate dehydrogenase kinase 4 (PDK4) in skeletal muscle are key regulators of the glucose and lipid metabolic processes that are involved in insulin resistance. Medium-chain fatty acids (MCFAs) have anti-obesogenic effects in rodents and humans, while long-chain fatty acids (LCFAs) cause increases in body weight and insulin resistance. To clarify the beneficial effects of MCFAs, we examined UCP3 and PDK4 expression in skeletal muscles of mice fed a MCFA- or LCFA-enriched high-fat diet (HFD). Five-week feeding of the LCFA-enriched HFD caused high body weight gain and induced glucose intolerance in mice, compared with those in mice fed the MCFA-enriched HFD. However, the amounts of UCP3 and PDK4 transcripts in the skeletal muscle of mice fed the MCFA- or LCFA-enriched HFD were similar. To further elucidate the specific effects of MCFAs, such as capric acid (C10:0), on lipid metabolism in skeletal muscles, we examined the effects of various FAs on expression of UCP3 and PDK4, in mouse C2C12 myocytes. Although palmitic acid (C16:0) and lauric acid (C12:0) significantly induced expression of both UCP3 and PDK4, capric acid (C10:0) upregulated only UCP3 expression via activation of peroxisome proliferator-activated receptor-δ. Furthermore, palmitic acid (C16:0) disturbed the insulin-induced phosphorylation of Akt, while MCFAs, including lauric (C12:0), capric (C10:0), and caprylic acid (C12:0), did not. These results suggest that capric acid (C10:0) increases the capacity for fatty acid oxidation without inhibiting glycolysis in skeletal muscle.
Departments of Nutritional Physiology, Tokushima University Graduate School.
Tomoki
T
Abe
Katsuya
K
Hirasaka
Shohei
S
Kohno
Chisato
C
Tomida
Marie
M
Haruna
Takayuki
T
Uchida
Ayako
A
Ohno
Motoko
M
Oarada
Shigetada
S
Teshima-Kondo
Yuushi
Y
Okumura
Inho
I
Choi
Toshiaki
T
Aoyama
Junji
J
Terao
Takeshi
T
Nikawa
D000818:Animals; D002460:Cell Line; D003652:Decanoic Acids / Q000494:pharmacology*; D059305:Diet, High-Fat; D005227:Fatty Acids / Q000008:administration & dosage; D015870:Gene Expression / Q000187:drug effects; D006019:Glycolysis / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D047494:PPAR delta / Q000037:antagonists & inhibitors / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D000071247:Uncoupling Protein 3 / Q000235:genetics*; D015854:Up-Regulation
D003652:Decanoic Acids; D005227:Fatty Acids; D047494:PPAR delta; D012333:RNA, Messenger; D000071247:Uncoupling Protein 3; C031071:decanoic acid; D011494:Protein Kinases; C403287:pyruvate dehydrogenase kinase 4