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结蛋白缺失导致骨骼肌对机械性超负荷的适应性反应受损。

Absence of Desmin Results in Impaired Adaptive Response to Mechanical Overloading of Skeletal Muscle.

作者信息

Joanne Pierre, Hovhannisyan Yeranuhi, Bencze Maximilien, Daher Marie-Thérèse, Parlakian Ara, Toutirais Geraldine, Gao-Li Jacqueline, Lilienbaum Alain, Li Zhenlin, Kordeli Ekaterini, Ferry Arnaud, Agbulut Onnik

机构信息

Sorbonne Université, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, Inserm ERL U1164, Biological Adaptation and Ageing, Paris, France.

U955-IMRB, Team 10, Biology of the Neuromuscular System, Inserm, UPEC, ENVA, EFS, Créteil, France.

出版信息

Front Cell Dev Biol. 2021 Jul 15;9:662133. doi: 10.3389/fcell.2021.662133. eCollection 2021.

Abstract

Desmin is a muscle-specific protein belonging to the intermediate filament family. Desmin mutations are linked to skeletal muscle defects, including inherited myopathies with severe clinical manifestations. The aim of this study was to examine the role of desmin in skeletal muscle remodeling and performance gain induced by muscle mechanical overloading which mimics resistance training. Plantaris muscles were overloaded by surgical ablation of gastrocnemius and soleus muscles. The functional response of plantaris muscle to mechanical overloading in desmin-deficient mice (KO, = 32) was compared to that of control mice ( = 36) after 7-days or 1-month overloading. To elucidate the molecular mechanisms implicated in the observed partial adaptive response of KO muscle, we examined the expression levels of genes involved in muscle growth, myogenesis, inflammation and oxidative energetic metabolism. Moreover, ultrastructure and the proteolysis pathway were explored. Contrary to control, absolute maximal force did not increase in KO muscle following 1-month mechanical overloading. Fatigue resistance was also less increased in KO as compared to control muscle. Despite impaired functional adaptive response of KO mice to mechanical overloading, muscle weight and the number of oxidative MHC2a-positive fibers per cross-section similarly increased in both genotypes after 1-month overloading. However, mechanical overloading-elicited remodeling failed to activate a normal myogenic program after 7-days overloading, resulting in proportionally reduced activation and differentiation of muscle stem cells. Ultrastructural analysis of the plantaris muscle after 1-month overloading revealed muscle fiber damage in KO, as indicated by the loss of sarcomere integrity and mitochondrial abnormalities. Moreover, the observed accumulation of autophagosomes and lysosomes in KO muscle fibers could indicate a blockage of autophagy. To address this issue, two main proteolysis pathways, the ubiquitin-proteasome system and autophagy, were explored in KO and control muscle. Our results suggested an alteration of proteolysis pathways in KO muscle in response to mechanical overloading. Taken together, our results show that mechanical overloading increases the negative impact of the lack of desmin on myofibril organization and mitochondria. Furthermore, our results suggest that under these conditions, the repairing activity of autophagy is disturbed. Consequently, force generation is not improved despite muscle growth, suggesting that desmin is required for a complete response to resistance training in skeletal muscle.

摘要

结蛋白是一种属于中间丝家族的肌肉特异性蛋白。结蛋白突变与骨骼肌缺陷有关,包括具有严重临床表现的遗传性肌病。本研究的目的是研究结蛋白在模拟抗阻训练的肌肉机械超负荷诱导的骨骼肌重塑和性能提升中的作用。通过手术切除腓肠肌和比目鱼肌使跖肌超负荷。在7天或1个月的超负荷后,将结蛋白缺陷小鼠(KO,n = 32)的跖肌对机械超负荷的功能反应与对照小鼠(n = 36)进行比较。为了阐明与观察到的KO肌肉部分适应性反应相关的分子机制,我们检测了参与肌肉生长、肌发生、炎症和氧化能量代谢的基因表达水平。此外,还探索了超微结构和蛋白水解途径。与对照相反,在1个月的机械超负荷后,KO肌肉的绝对最大力量没有增加。与对照肌肉相比,KO肌肉的抗疲劳能力增加也较少。尽管KO小鼠对机械超负荷的功能适应性反应受损,但在1个月的超负荷后,两种基因型的肌肉重量和每横截面积的氧化型MHC2a阳性纤维数量同样增加。然而,在7天的超负荷后,机械超负荷引起的重塑未能激活正常的肌发生程序,导致肌肉干细胞的激活和分化成比例减少。1个月超负荷后跖肌的超微结构分析显示KO肌肉中有肌纤维损伤,表现为肌节完整性丧失和线粒体异常。此外,在KO肌纤维中观察到的自噬体和溶酶体积累可能表明自噬受阻。为了解决这个问题,在KO和对照肌肉中探索了两条主要的蛋白水解途径,即泛素-蛋白酶体系统和自噬。我们的结果表明,在机械超负荷的情况下,KO肌肉中的蛋白水解途径发生了改变。综上所述,我们的结果表明,机械超负荷增加了结蛋白缺乏对肌原纤维组织和线粒体的负面影响。此外,我们的结果表明,在这些条件下,自噬的修复活性受到干扰。因此,尽管肌肉生长,但力量产生并未改善,这表明结蛋白是骨骼肌对抗阻训练产生完整反应所必需 的。

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