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 7

Myostatin mRNA is a RIDD target of IRE1α.

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Myostatin mRNA is a RIDD target of IRE1α. (A) Sequence alignment of Mstn...
(A) Sequence alignment of Mstn mRNAs from the indicated species with the putative conserved RIDD region, with the predicted stem-loop secondary structure shown for human and mouse Mstn mRNA. The potential IRE1α cleavage site is indicated by an arrow. (B) Fluorescence-based analysis of IRE1α cleavage of the synthetic WT or mutant (mut, GC to CA) Mstn mRNA (n = 3 independent experiments). (C) Quantitative RT-PCR analysis of the abundance of Mstn mRNA in HEK293T cells cotransfected with plasmids expressing the entire coding region of WT or mutant myostatin (GC to CA) together with empty vector or human IRE1α expression plasmid (n = 4 independent experiments). (D) HEK293T cells were cotransfected with plasmids expressing the WT or stem-loop deletion (ΔSL) mutant myostatin together with vector (Vec) control or plasmids expressing FLAG-tagged human WT or deletion mutant (KR, kinase and RNase domain; R, RNase domain) IRE1α proteins. Representative RT-PCR analysis of Mstn mRNA from immunoprecipitates (IP) using anti-FLAG antibody or from total cellular RNA (Input). Shown also are representative immunoblots of immunoprecipitated IRE1α proteins and IgG control (n = 3 independent experiments). (E and F) The stability of the Mstn mRNA was determined by quantitative RT-PCR in C2C12 myotubes infected with Sh-Con or Sh-Ern1 adenoviruses (E), or Ad-Con or Ad-IRE1α adenoviruses (F), after treatment with actinomycin D (ActD) for the indicated time intervals. Data are shown relative to the value at time 0 of ActD treatment (set as 1) after normalization to the GAPDH mRNA level as internal control (n = 3 independent experiments). All data are shown as mean ± SEM. Significance was calculated by 2-way ANOVA with Bonferroni’s multiple-comparison test. *P < 0.05, **P < 0.01, ***P < 0.001. ###P < 0.001. Scale bars: 100 μm.