Department of Geriatrics, Regenerative Medicine Research Center, Laboratory of Stem cell biology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Keyuan 4-1, Gaopeng Street, High-tech Zone, Chengdu 610041, China.
Lipids Health Dis. 2013 Jul 18;12:104. doi: 10.1186/1476-511X-12-104.
Excessive circular fatty acid, particlarly saturated fatty acid, can result in insulin resistance in skeletal muscle, but other adverse effects of fatty acid accumulation in myocytes remain unclear.
Differentiated C2C12 myotubes were used. The effects of palmitate on cell viability, glucose uptake, gene expression and myotube loss were evaluated by MTT assay, 2NBDG uptake, qRT-PCR, Western Blot and crystal staining-based myotube counting, respectively. In some expreiments, oleate was administrated, or the inhibitors of signaling pathways were applied.
Palmitate-induced cellular insulin resistance was clarified by the reduced Akt phosphorylation, glucose uptake and Glut4 expression. Palmitate-caused myotube loss was clearly observed under microscope and proved by myotube counting and expression analysis of myotube marker genes. Moreover, palmitate-induced transcriptional suppression of three health benefit myokine genes (FNDC5, CTRP15 and FGF21) was found, and the different involvement of p38 and PI3K in the transcription of these genes was noticed.
Palmitate-induced insulin resistance accompanys myotube loss and the impaired expression of FNDC5, CTRP15 and FGF21genes in C2C12 myotubes. These results provide novel evidence indicating the negative role of high concentration of palmitate in myotubes.
过多的环状脂肪酸，特别是饱和脂肪酸，可导致骨骼肌胰岛素抵抗，但脂肪酸在肌细胞中积累的其他不良影响尚不清楚。
使用分化的 C2C12 肌管。通过 MTT 测定、2NBDG 摄取、qRT-PCR、Western Blot 和基于结晶染色的肌管计数分别评估棕榈酸对细胞活力、葡萄糖摄取、基因表达和肌管损失的影响。在一些实验中，给予油酸或应用信号通路抑制剂。
棕榈酸诱导的 Akt 磷酸化减少、葡萄糖摄取和 Glut4 表达降低，明确了细胞胰岛素抵抗。在显微镜下明显观察到棕榈酸引起的肌管损失，并通过肌管计数和肌管标记基因的表达分析得到证实。此外，还发现棕榈酸诱导三种健康益处肌源基因（FNDC5、CTRP15 和 FGF21）的转录抑制，并且注意到 p38 和 PI3K 对这些基因的转录有不同的参与。
棕榈酸诱导的胰岛素抵抗伴随着 C2C12 肌管中的肌管损失和 FNDC5、CTRP15 和 FGF21 基因表达受损。这些结果提供了新的证据，表明高浓度棕榈酸在肌管中具有负面作用。
