Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan.
Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan.
Biochem Biophys Res Commun. 2020 Apr 30;525(2):406-411. doi: 10.1016/j.bbrc.2020.02.099. Epub 2020 Feb 22.
Skeletal muscle is divided into type 1 and type 2 fibers. Type 1 fibers are rich in mitochondria, have high oxidative metabolism, and are resistant to fatigue. Muscle-specific overexpression of peroxisome proliferator-activated receptor (PPAR)δ drastically increases the number of type 1 fibers. We focused on oleic acid, an omega-9 monounsaturated fatty acid, as a factor that activates PPARδ. In this study, we examined the effects of oleic acid on the muscle fiber type of C2C12 myotubes and its relationship with PPARδ. Our results showed that oleic acid treatment increased the levels of myosin heavy chain (MyHC)1, a known type 1 fiber marker, as well as mitochondrial mass and maximum respiration in C2C12 cells. To confirm the relationship between PPARδ activation and oleic acid-induced MyHC1 increase, we examined the effects of oleic acid in PPARδ knockdown C2C12 myoblasts. We found that oleic acid supplementation increased the mRNA expression of MyHC1 in PPARδ-knockdown C2C12 cells. Our data suggest that oleic acid increases type 1 fiber levels in C2C12 myotubes in a PPARδ-independent manner.
骨骼肌分为 1 型和 2 型纤维。1 型纤维富含线粒体，具有较高的氧化代谢能力，不易疲劳。肌肉特异性过表达过氧化物酶体增殖物激活受体 (PPAR)δ 可显著增加 1 型纤维的数量。我们将 ω-9 单不饱和脂肪酸油酸作为激活 PPARδ 的因素。在这项研究中，我们研究了油酸对 C2C12 肌管肌纤维类型的影响及其与 PPARδ 的关系。结果表明，油酸处理可增加肌球蛋白重链 (MyHC)1 的水平，MyHC1 是一种已知的 1 型纤维标志物，同时还可增加 C2C12 细胞中线粒体的质量和最大呼吸作用。为了确认 PPARδ 激活与油酸诱导的 MyHC1 增加之间的关系，我们研究了油酸在 PPARδ 敲低 C2C12 成肌细胞中的作用。结果发现，油酸补充可增加 PPARδ 敲低的 C2C12 细胞中 MyHC1 的 mRNA 表达。我们的数据表明，油酸以 PPARδ 独立的方式增加 C2C12 肌管中的 1 型纤维水平。
