失神经骨骼肌萎缩中泛素蛋白连接酶Murf1和核转录因子NF-κB表达与被动运动干预

Expression of ubiquitin-protein ligase Murf1 and nuclear factor kappa B in denervated amyotrophy intervened by passive movement

背景:蛋白质分解是延缓肌萎缩发生的关键环节,在慢性病性、制动性肌萎缩中泛素蛋白连接酶Murf1和核转录因子NF-κB的表达增加,被动运动已被证实可以有效抑制肌萎缩的发生。目的:探讨泛素蛋白连接酶Murf1和核转录因子NF-κB在大鼠失神经肌萎缩中不同时段的表达,以及被动运动对失神经骨骼肌Murf1和NF-κB表达的影响。方法:假手术组大鼠不切断右下肢坐骨神经,失神经组、失神经被动运动组大鼠切断右下肢坐骨神经。术后1d起,将失神经被动运动组大鼠置于自制的网夹内,拉出右后肢,抓住趾部,与脊柱呈45°向后外方牵拉,至右后肢完全伸直,再将右后肢推向身体,使之完全屈曲紧贴身体,每天训练2次,每次屈伸运动300下,3min/次,直至切取标本之日。干预2,14,28d后,采用RT-PCR与WesternBlot技术分别检测Murf1,NF-κBmRNA和蛋白质的表达。结果与结论:与假手术组比较,各时间点失神经组Murf1,NF-κBmRNA及蛋白的表达均明显增加(P<0.05);与失神经组比较,各时间点失神经被动运动组Murf1及NF-κBmRNA的表达均显著降低(P<0.01)。失神经支配后肌湿质量比明显下降,被动运动14d时肌湿质量比明显高于失神经组(P<0.05)。失神经腓肠肌中Murf1,NF-κBmRNA和蛋白的表达与肌湿质量呈负相关(r=-0.795,P<0.01;r=-0.834,P<0.01),提示被动运动可能通过降低Murf1和NF-κB的表达发挥肌萎缩防治作用。

BACKGROUND：Protein degradation is a key link in delaying amyotrophy.The expressions of muscle ring finger protein（Murf1） and nuclear factor κB（NF-κB） are increased in amyotrophy,and studies have been demonstrated that passive movement can suppress the occurrence of amyotrophy.OBJECTIVE：To investigate expression pattern of Murf1 and NF-κB during denervated amyotrophy.at different time points,and to explore effects of passive movement on the expression of Murf1 and NF-κB in denervated amyotrophy.METHODS：Sciatic nerves of rats were cut down in the denervated and passive movement groups.Sham operation was performed in the sham-operated group.Rats in the passive movement group were performed passive movement（45° traction and full range flexion） at 1 day after operation,twice per day,300 frequency per time.The expressions of Murf1 and NF-κB were determined by RT-PCR and Western blot at 2,14 and 28 days after intervention.RESULTS AND CONCLUSION：Compared with the sham-operated group,the expressions of Murf1,NF-κB mRNA and protein in the denervated group were obviously increased at each time points（P 0.05）.Compared with the denervation group,the expressions of Murf1,NF-κB mRNA in the passive movement group were dramatically decreased（P 0.01）.The muscle wet weight was obviously decreased after denervation,which was greater in the positive movement group than that of the denervation group at 14 days（P 0.05）.The expression of mRNA and protein of Murf1 and NF-κB were negatively correlated to muscle wet weight in the denervated group（r =-0.795,P 0.01;r =-0.834,P 0.01）.Passive movement can prevent amyotrophy by reducing the expressions of Murf1 and NF-κB.