肿瘤坏死因子α对COPD大鼠骨骼肌蛋白酶体C2亚基表达的影响

Effect of Tumor Necrosis Factor-α on Expression of Skeletal Muscle Proteasome Subunit C2 in Rats with Chronic Obstructive Pulmonary Disease

目的研究COPD大鼠骨骼肌蛋白酶体C2亚基的表达,以及TNF-α对其表达的影响,探讨COPD大鼠骨骼肌蛋白高分解代谢的机制。方法SD大鼠随机分为对照组、COPD组及COPD+TNF-α组,每组15只。COPD组和COPD+TNF-α组大鼠用单纯熏香烟法制成COPD大鼠动物模型,分离其伸趾长肌,分别给予不含和含TNF-α(10μg/L)的孵育液进行离体有氧孵育。利用实时定量PCR和Western blot技术检测C2亚基在转录和蛋白水平的变化。结果COPD组和COPD+TNF-α组C2亚基mRNA表达为对照组的1.74倍和1.95倍(P均<0.01),其中COPD+TNF-α组显著高于COPD组(P<0.01)。COPD组和COPD+TNF-α组C2亚基蛋白表达也显著高于对照组(1.04±0.15和1.23±0.16比0.71±0.12,P<0.05和P<0.01),COPD组和COPD+TNF-α组表达无显著差异(P>0.05)。结论COPD时骨骼肌蛋白降解增加可能是经由TNF-α激活泛素-蛋白酶体途径所致。

Objective To study the effect of tumor necrosis factor-α （TNF-α） on hypermetabolism of skeletal muscle protein in rats with chronic obstructive pulmonary disease （COPD） and explore its underlying mechanism. Methods Forty-five SD rats were randomly divided into a normal control group,a COPD group and a COPD ＋ TNF-α group, with 15 rats in each group. COPD model was established by passive cigarette smoking in COPD group and COPD ＋ TNF-α group. Then the extensor digitorium longus muscles （EDL） were dissected and incubated in vitro muscle incubation system with adequate oxygen supply. The EDL were either cultured with or without recombinant rat TNF-α （ 10 μg/L）. The mRNA and protein expressions of proteasome subunit C2 in EDL were quantified by real-time quantitative PCR and Western blot analysis,respectively. Results The mRNA and protein expressions of proteasome subunit C2 were both significant higher in the COPD group and COPD ＋ TNF-α group than those in the normal control group（P 〈 0. 01 or 0. 05）. The COPD ＋ TNF-α group had higher expression of proteasome subunit C2 mRNA than that in the COPD group（ P 〈0. 01 ） ,whereas the protein expression was not significantly different（ P 〉 0. 05）. Conclusion Ineresed proteolytic metabolism in skeletal muscle in COPD might be regulated by TNF-α activated ublquitin-dependent pathway.