Morales María Gabriela, Abrigo Johanna, Meneses Carla, Cisternas Franco, Simon Felipe, Cabello-Verrugio Claudio
Laboratorio de Biología y Fisiopatología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas & Facultad de Medicina, Universidad Andres Bello, Avenida República 239, 8370146, Santiago, Chile.
Histochem Cell Biol. 2015 Feb;143(2):131-41. doi: 10.1007/s00418-014-1275-1. Epub 2014 Sep 11.
Skeletal muscle atrophy during sepsis, immobilization, and chronic diseases is characterized by an increase in expression and activity of the muscle-specific ubiquitin 3 ligases atrogin-1 and MuRF-1. The classical renin-angiotensin system (RAS), by high level of circulating angiotensin II (AngII) is directly involved in skeletal muscle wasting associated with cardiac and renal failure. Ang (1-7), a peptide belonging to the non-classical RAS system, produces effects that are opposite to AngII. The actions of Ang (1-7) are mediated by its binding and signalling through the Mas receptor. Our purpose is to assess the effects of atrophic stimuli AngII, lipopolysaccharide (LPS), and immobilization on the expression of the Mas receptor in skeletal muscle. For that we used gastrocnemius and tibialis anterior muscles of C57BL10 mice treated with AngII, LPS or subjected to unilateral hindlimb immobilization by casting. In addition, we used C2C12 myotubes incubated with AngII or LPS. We evaluated Mas expression by quantitative real-time PCR, Western blot immunohistochemical analysis. Skeletal muscle atrophy was corroborated by the expression of atrogin-1 and MuRF-1 and the fibre diameter. Our results show that Mas receptor expression was increased by AngII or LPS in vitro and in vivo, and upregulated by immobilization. The increase of the Mas expression was concomitantly with the upregulation of atrogin-1 and MuRF-1 and the reduction of the fibre diameter. These results from studies in vitro and in vivo demonstrate for the first time that the Mas receptor is increased under atrophic stimulus and suggest that the non-classical RAS system could have an important role in muscle wasting.
脓毒症、肢体固定和慢性疾病期间的骨骼肌萎缩，其特征在于肌肉特异性泛素3连接酶atrogin-1和MuRF-1的表达及活性增加。经典肾素-血管紧张素系统（RAS）通过高水平循环的血管紧张素II（AngII），直接参与与心力衰竭和肾衰竭相关的骨骼肌消耗。Ang (1-7)是一种属于非经典RAS系统的肽，其产生的效应与AngII相反。Ang (1-7)的作用是通过其与Mas受体结合并发出信号来介导的。我们的目的是评估萎缩刺激物AngII、脂多糖（LPS）和肢体固定对骨骼肌中Mas受体表达的影响。为此，我们使用了经AngII、LPS处理或通过铸型进行单侧后肢固定的C57BL10小鼠的腓肠肌和胫前肌。此外，我们使用了与AngII或LPS孵育的C2C12肌管。我们通过定量实时PCR、蛋白质免疫印迹和免疫组织化学分析来评估Mas的表达。通过atrogin-1和MuRF-1的表达以及纤维直径来证实骨骼肌萎缩。我们的结果表明，在体外和体内，AngII或LPS均可增加Mas受体的表达，而肢体固定可使其上调。Mas表达的增加与atrogin-1和MuRF-1的上调以及纤维直径的减小同时出现。这些体外和体内研究结果首次证明，在萎缩刺激下Mas受体增加，提示非经典RAS系统可能在肌肉消耗中起重要作用。
