Hemojuvelin is a novel suppressor for Duchenne muscular dystrophy and age-related muscle wasting
Hemojuvelin is a novel suppressor for Duchenne muscular dystrophy and age-related muscle wasting
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血幼素是杜氏肌营养不良症和年龄相关性肌肉萎缩的新型抑制剂
DOI：
10.1002/jcsm.12414
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发表时间：
2019
影响因子：
8.9
通讯作者：
Chen Xiaoping
中科院分区：
文献类型：
--
作者：
Zhang Peng;He Jian;Wang Fei;Gong Jing;Wang Lu;Wu Qian;Li Wenjiong;Liu Hongju;Wang Jing;Zhang Kunshan;Li Mao;Huang Xusheng;Pu Chuanqiang;Li Ying;Jiang Fengjie;Wang Fudi;Min Junxia;Chen Xiaoping
研究背景肌肉萎缩是由多种生理和病理条件引起的，包括衰老和杜氏肌营养不良症（DMD）。转化生长因子-β1（TGF-β1）有助于老年人和DMD患者的肌肉发病机制;抑制TGF-β1信号传导是肌肉萎缩性疾病的一种有前途的治疗策略。Hemojuvelin（HJV或作为鼠同源物的Hemojuvelin）是一种膜结合蛋白，在骨骼肌、心脏和肝脏中高度表达。在肝细胞中，组胺作为骨形态发生蛋白（TGF-β亚家族成员）的辅助受体。本研究的目的是探讨HxD是否通过作为TGF-β1信号的辅助受体在肌肉生理和病理生理过程中发挥重要作用。方法采用常规和条件性HxD基因敲除小鼠以及转染HxD过表达载体的mdx和老年小鼠，研究HxD在肌肉生理和病理生理中的作用。进行qRT-PCR、蛋白质印迹和免疫组织化学检查以评估体内和体外的基因、蛋白质和结构变化。运动耐力测定采用跑台试验，肌力测定采用等长传感器。RNA干扰，免疫沉淀，和双荧光素酶报告基因检测被用来探索Hjv调节TGF-β1信号在骨骼肌中的机制。ResultsConventional和conditionalHjv基因敲除小鼠显示肌肉萎缩，纤维化，降低跑步耐力，和肌肉力量。HJV在DMD患者（n= 3，平均年龄：11.7 ± 5.7岁）和mdx小鼠以及老年人（n= 10，20%女性，平均年龄：75.1 ± 9.5岁）和小鼠的肌肉中显著下调。过表达HSP 70可挽救营养不良性和年龄相关性肌肉萎缩。与其在肝细胞中的功能不同，骨形态发生蛋白下游磷酸化的p-Smad 1/5/8信号通路未发生变化，但TGF-β1、TGF-β受体II（TβRII）和p-Smad 2/3表达在HcB缺乏的肌肉中增加。从机制上讲，HJV的丧失促进了TGF-β1诱导的Smad 3信号传导的激活，而HJV过表达通过直接与肌膜上的TβRII相互作用抑制了TGF-β 1/Smad 3信号传导。与TGF-β1/Smad 3通路不同，HJV可能是一个可靠的药物靶点，因为它的表达并不广泛。可以设计新的治疗策略，仅干扰HJV的肌肉功能，以治疗DMD和年龄相关的肌肉萎缩。
BackgroundMuscle wasting occurs in response to various physiological and pathological conditions, including ageing and Duchenne muscular dystrophy (DMD). Transforming growth factor‐β1 (TGF‐β1) contributes to muscle pathogenesis in elderly people and DMD patients; inhibition of TGF‐β1 signalling is a promising therapeutic strategy for muscle‐wasting disorders. Hemojuvelin (HJV or Hjv as the murine homologue) is a membrane‐bound protein that is highly expressed in skeletal muscle, heart, and liver. In hepatic cells, Hjv acts as a coreceptor for bone morphogenetic protein, a TGF‐β subfamily member. The aim of this study was to investigate whether Hjv plays an essential role in muscle physiological and pathophysiological processes by acting as a coreceptor for TGF‐β1 signalling.MethodsConventional and conditionalHjvknockout mice as well asmdxand aged mice transfected with Hjv overexpression vector were used to study the role of Hjv in muscle physiology and pathophysiology. qRT‐PCR, western blotting, and immunohistochemistry examinations were conducted to evaluate gene, protein, and structural changesin vivoandin vitro. Exercise endurance was determined using treadmill running test, and muscle force was detected by an isometric transducer. RNA interference, immunoprecipitation, and dual‐luciferase reporter assays were utilized to explore the mechanism by which Hjv regulates TGF‐β1 signalling in skeletal muscle.ResultsConventional and conditionalHjvknockout mice displayed muscle atrophy, fibrosis, reduced running endurance, and muscle force. HJV was significantly down‐regulated in the muscles of DMD patients (n= 3, mean age: 11.7 ± 5.7 years) andmdxmice as well as in those of aged humans (n= 10, 20% women, mean age: 75.1 ± 9.5 years) and mice. Overexpression of Hjv rescued dystrophic and age‐related muscle wasting. Unlike its function in hepatic cells, the bone morphogenetic protein downstream phosphorylated p‐Smad1/5/8 signalling pathway was unchanged, but TGF‐β1, TGF‐β receptor II (TβRII), and p‐Smad2/3 expression were increased inHjv‐deficient muscles. Mechanistically, loss of Hjv promoted activation of Smad3 signalling induced by TGF‐β1, whereas Hjv overexpression inhibited TGF‐β1/Smad3 signalling by directly interacting with TβRII on the muscle membrane.ConclusionsOur findings identify an unrecognized role of HJV in skeletal muscle by regulating TGF‐β1/Smad3 signalling as a coreceptor for TβRII. Unlike the TGF‐β1/Smad3 pathway, HJV could be a reliable drug target as its expression is not widespread. Novel therapeutic strategies could potentially be devised to interfere only with the muscle function of HJV to treat DMD and age‐related muscle wasting.