Atrolnc-1在制动诱导小鼠后肢肌萎缩中的作用研究*

目的: 探讨Atrolnc-1在制动诱导小鼠后肢肌萎缩中的作用。方法: 将雄性C57BL/6小鼠随机分为对照组(Control)和制动组(Immobilization),每组10只。对照组不作任何实验处理,制动组小鼠右侧后肢装入自制塑料制动器固定。2周后分离其腓肠肌,用苏木素-伊红(HE)染色并观察腓肠肌形态学改变,测定肌纤维横截面积。采用实时荧光定量PCR(QRT-PCR)检测肌肉萎缩F-box蛋白(Atrogin-1)及肌萎缩特异性长链非编码RNA Atrolnc-1的变化。蛋白免疫印迹(WB)检测Atrogin-1、肌肉环状指蛋白1(MuRF-1)、胞浆及胞核p-NF-κB蛋白的表达。结果: 制动2周后小鼠腓肠肌萎缩。与对照组相比,制动组小鼠腓肠肌湿重减少(P＞0.05),腓肠肌湿重/体重千分比明显降低(P＜0.05);HE染色可见制动组骨骼肌大量肌纤维缩小或溶解,肌纤维横纹排列紊乱,间质见炎症细胞浸润;肌纤维横截面积减少(P＜0.01)。QRT-PCR及WB结果显示,Atrolnc-1表达上升(P＜0.01),胞浆p-NF-κB蛋白表达减少(P＜0.01),但胞核p-NF-κB蛋白表达升高(P＜0.01),同时Atrogin-1(P＜0.01)与MuRF-1(P＜0.01)表达均升高。结论: 制动诱导小鼠腓肠肌萎缩,可能与Atrolnc-1激活NF-κB入核,促进MuRF-1表达增加有关。

Effects of Atrolnc-1 on immobilization induced muscular atrophy in mice hindlimbs

Objective: To investigate the effects of Atrolnc-1 on immobilization induced muscular atrophy in mice hindlimbs. Methods: Male C57BL/6 mice were randomly divided into control group and immobilization group (n=10 per group). The control group did not receive any treatment. The right hindlimb of the Iimmobilization group was fixed by self-made plastic tube. After 2 weeks' immobilization, the gastrocnemius muscle was separated. Hematoxylin-eosin (HE) staining was used to observe the morphological changes and the cross-sectional area was calculated. The expressions of Atrogin-1 and atrophy-specific long non-coding RNA Atrolnc-1 were detected by quantitative real-time PCR (QRT-PCR). Western blot (WB) was used to detect the expressions of muscular atrophy fbox-1 protein (MAFbx/Atrogin-1), muscle ring finger1 (MuRF-1) in whole cell and phosphonated of nuclear factor kappaB (p-NF-κB) in cytoplasm and nucleus. Results: The gastrocnemius muscle was atrophy after 2 weeks' immobilization. Compared with the control group, the wet weight of gastrocnemius muscle was decreased (P＞0.05) and the permillage of wet weight/weight of gastrocnemius muscle was decreased significantly (P＜0.05). HE staining showed that the number of muscle fibers in the immobilization group were reduced, the muscle fibers were dissolved and arranged disorderly and the interstitial inflammatory cells were infiltrated; the cross-sectional area of muscle fibers was decreased (P＜0.01).The expression level of atrolnc-1 was increased in immobilization group (P＜0.01). The expression level of p-NF-κB in cytoplasm was decreased (P＜0.01), while the expression level of p-NF-κB was increased in nucleus ( P＜0.01). Besides, the expressions of atrogin-1 (P＜0.01) and MuRF-1 (P＜0.01) were increased. Conclusion: Immobilization induced gastrocnemius atrophy in mice may be related to the activation of NF-κB by Atrolnc-1 and then promote MuRF-1 expression.