IRE1α regulates skeletal muscle regeneration through myostatin mRNA decay
Shengqi He, … , Zhenji Gan, Yong Liu
Shengqi He, … , Zhenji Gan, Yong Liu
Published July 20, 2021
Citation Information: J Clin Invest. 2021;131(17):e143737. https://doi.org/10.1172/JCI143737.
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Research Article Muscle biology

IRE1α regulates skeletal muscle regeneration through myostatin mRNA decay

Abstract

Skeletal muscle can undergo a regenerative process in response to injury or disease to preserve muscle mass and function, which are critically influenced by cellular stress responses. Inositol-requiring enzyme 1 (IRE1) is an ancient endoplasmic reticulum stress sensor and mediates a key branch of the unfolded protein response. In mammals, IRE1α is implicated in the homeostatic control of stress responses during tissue injury and regeneration. Here, we show that IRE1α serves as a myogenic regulator in skeletal muscle regeneration in response to injury and muscular dystrophy. We found in mice that IRE1α was activated during injury-induced muscle regeneration, and muscle-specific IRE1α ablation resulted in impaired regeneration upon cardiotoxin-induced injury. Gain- and loss-of-function studies in myocytes demonstrated that IRE1α acts to sustain both differentiation in myoblasts and hypertrophy in myotubes through regulated IRE1-dependent decay (RIDD) of mRNA encoding myostatin, a key negative regulator of muscle repair and growth. Furthermore, in the mouse model of Duchenne muscular dystrophy, loss of muscle IRE1α resulted in augmented myostatin signaling and exacerbated the dystrophic phenotypes. These results reveal a pivotal role for the RIDD output of IRE1α in muscle regeneration, offering insight into potential therapeutic strategies for muscle loss diseases.

Authors

Shengqi He, Tingting Fu, Yue Yu, Qinhao Liang, Luyao Li, Jing Liu, Xuan Zhang, Qian Zhou, Qiqi Guo, Dengqiu Xu, Yong Chen, Xiaolong Wang, Yulin Chen, Jianmiao Liu, Zhenji Gan, Yong Liu

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Figure 8

Pharmacological inhibition of IRE1α RNase activity impairs muscle cell differentiation and growth.

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Pharmacological inhibition of IRE1α RNase activity impairs muscle cell d...
(A–E) Primary myoblasts isolated from WT mice were cultured in growth medium (GM), and subsequently incubated in differentiation medium (DM) with or without 4μ8C for 3 days (n = 4 independent experiments). (A) Quantitative RT-PCR analysis of Xbp1 mRNA splicing and the mRNA abundance of Blos1 and Mstn. (B) Immunoblot analysis of the expression of the indicated proteins. (C) Quantification of MyoG/tubulin, MyHC/tubulin, and p-Smad3/Smad3 levels. (D) MyHC immunostaining. (E) Quantification of the fusion index. (F and G) Differentiated C2C12 myotubes were treated for 24 hours with DMSO versus 5 μM or 10 μM 4μ8C. (F) Quantitative RT-PCR analysis of Xbp1 mRNA splicing and the Mstn mRNA abundance (n = 4 independent experiments). (G) Immunoblot analysis of the indicated proteins (n = 3 independent experiments). (H and I) C2C12 myoblasts infected by EGFP-expressing adenovirus were differentiated for 4 days and likewise treated with 4μ8C (n = 4 independent experiments). (H) Representative images of myotubes by fluorescence microscopy. (I) Quantification of myotube diameters using ImageJ software. All data are shown as mean ± SEM. Significance was calculated by 1-way ANOVA with Bonferroni’s multiple-comparison test. *P < 0.05, **P < 0.01, ***P < 0.001. Scale bars: 100 μm.