Nozhenko Yuriy, Rodríguez Ana M, Palou Andreu
Laboratory of Molecular Biology, Nutrition and Biotechnology (Nutrigenomics), University of the Balearic Islands (UIB) and CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Palma de Mallorca, Spain.
Cell Physiol Biochem. 2015;35(1):92-103. doi: 10.1159/000369678. Epub 2015 Jan 2.
Skeletal muscle can experience pronounced metabolic adaptations in response to extrinsic stimuli, and expresses leptin receptor (OB-Rb). We aimed to further the understanding of leptin effects on muscle cells, by studying the expression of key energy metabolism genes in C2C12 myotubes.
We performed a dose-time-dependent study with physiological concentrations of leptin: 5, 10 and 50 ng/ml, for 0, 30', 3h, 6h, 12h and 24h, also monitoring time-course changes in non-treated cells. mRNA levels were analyzed by RT-qPCR and peroxisome proliferator activated receptor γ coactivator 1α (PGC1α) protein levels by western blot.
The most significant effects were observed with 50 ng/ml leptin. In the short-term (30' and/or 3h), leptin significantly induced the expression of PGC1α, muscle carnitine palmitoyl transferase 1 (mCPT1), uncoupling protein 3 (UCP3), OB-Rb, Insulin receptor (InsR) and interleukins 6 and 15 (IL6, IL15). There was a decrease in mRNA levels of pyruvate dehydrogenase kinase 4 (PDK4) and mCPT1 in the long-term (24h). PGC1α protein levels were increased (24h).
Leptin rapidly induces the expression of genes important for its own response and the control of metabolic fuels, with the rapid responses of the genes encoding the master regulator PGC1α, mCPT1, UCP3, PDK4 and the signaling secretory molecule IL6 particularly interesting.
骨骼肌可对外源性刺激产生显著的代谢适应性变化，并表达瘦素受体（OB-Rb）。我们旨在通过研究C2C12肌管中关键能量代谢基因的表达，进一步了解瘦素对肌肉细胞的影响。
我们使用生理浓度的瘦素（5、10和50 ng/ml）进行了剂量-时间依赖性研究，持续时间为0、30分钟、3小时、6小时、12小时和24小时，同时监测未处理细胞的时间进程变化。通过RT-qPCR分析mRNA水平，通过蛋白质印迹法分析过氧化物酶体增殖物激活受体γ共激活因子1α（PGC1α）蛋白水平。
在50 ng/ml瘦素处理组中观察到最显著的效果。在短期（30分钟和/或3小时），瘦素显著诱导了PGC1α、肌肉肉碱棕榈酰转移酶1（mCPT）、解偶联蛋白3（UCP3）、OB-Rb、胰岛素受体（InsR）以及白细胞介素6和15（IL6、IL15）的表达。在长期（24小时），丙酮酸脱氢酶激酶4（PDK4）和mCPT1的mRNA水平有所下降。PGC1α蛋白水平升高（24小时）。
瘦素迅速诱导对其自身反应和代谢燃料控制重要的基因表达，编码主要调节因子PGC1α、mCPT1、UCP3、PDK4的基因以及信号分泌分子IL6的快速反应尤其令人感兴趣。
