5-氨基-4-甲酰胺咪唑核糖核苷酸对软脂酸诱导的C2C12细胞线粒体功能相关蛋白表达的影响

Effects of 5-aminoimidazole-4-carboxamide ribonucleotide on the palmitic acid-induced expression of mitochondrial function-related proteins in C2C12 skeletal muscle cells

研究脂质堆积诱发骨骼肌线粒体功能异常过程中，腺苷酸活化蛋白激酶（AMPK）激动剂对骨骼肌过氧化物酶体增殖物受体γ共激活因子1α（PGC1α）、线粒体融合蛋白2（Mfn2）、核呼吸因子1（NRF1）表达的影响。方法采用反转录聚合酶链式反应（RT—PCR）和免疫印迹（Western blotting）检测软脂酸干预下成肌细胞C2C12骨骼肌细胞PGC1α、Mfn2和NRF1表达水平。Western blotting检测哪种AMPK激动剂（AICAR、罗格列酮、二甲双胍）激活PGC1α作用最强及对骨骼肌细胞Mfn2和NRF1表达水平的影响，PGC1α激动剂上调和特异性小干扰RNA下调骨骼肌细胞PGC1α表达对Mfn2和NRF1的影响。结果软脂酸引起骨骼肌细胞PGC1α、Mfn2和NRF1表达水平下降（P〈0．05）。无论有无软脂酸存在，AICAR、罗格列酮、二甲双胍均能上调PGC1α表达，其中AICAR效果最明显（P〈0．05）。AICAR能逆转软脂酸诱发的骨骼肌细胞PGC1α、Mfn2和NRF1表达下降。Mfn2和NRF1蛋白表达水平随PGC1α表达水平增加而增加，表达水平下降而下降。结论AICAR能够缓解软脂酸对骨骼肌细胞PGC1α、Mfn2和NRF1表达的不利影响，并且可能通过增强PGC1α表达上调Mfn2和NRF1表达。

Objective To investigate the effects of activated protein kinase（AMPK）agonists on the expression of peroxisome proliferator-activated receptor 7 coactivator 1α （PGC1α, mitofusin 2 （Mfn2） and nuclear respiratory factorl （NRF1）in the process of lipid-induced mitochondrial dysfunction of skeletal muscles. Methods The expression of PGC1α,Mfn2 and NRF1 in C2C12 skeletal muscle cells after intervention with palmitic acid was detected using reverse transcription-polymerase chain reaction（RT-PCR）and Western blotting. The effect of 5-aminoimidazole-4-carboxamide ribonucleotide （AICAR）on Mfn2 and NRF1 and, the expression of Mfn2 and NRF1 in C2C12 cells induced by a PGC1α activator and PGC1α-siRNA were assessed by Western blotting. Results Palmitic acid decreased the mRNA and protein expression of PGC1α, Mfn2 and NRF1 in C2C12 cells （P〈0.05）. Additionally, AICAR, rosiglitazone and metformin up-regulated PGC1α expression, regardless of the presence of palmitic acid and, AICAR reversed lipid-induced PGC1α, Mfn2 and NRF1 attenuation in C2C12 cells. Furthermore,Mfn2 and NRF1 protein expression increased with PGC1α over-expression, and decreased with down-regulated PGC1α expression. Conclusions AICAR can relieve the adverse effects of palmitic acid on PGC1α, Mfn2 and NRF1 in skeletal muscle cells. Moreover, it appears that AICAR can un-regulate Mfn2 and NRF1 expression through activating PGC1α.