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Title: RhoA/ROCK signalling activated by ARHGEF3 promotes muscle weakness via autophagy in dystrophic mdx mice
Abstract Background

Duchenne muscular dystrophy (DMD), caused by dystrophin deficiency, leads to progressive and fatal muscle weakness through yet‐to‐be‐fully deciphered molecular perturbations. Emerging evidence implicates RhoA/Rho‐associated protein kinase (ROCK) signalling in DMD pathology, yet its direct role in DMD muscle function, and related mechanisms, are unknown.

Methods

Three‐dimensionally engineered dystrophin‐deficientmdxskeletal muscles andmdxmice were used to test the role of ROCK in DMD muscle functionin vitroandin situ, respectively. The role of ARHGEF3, one of the RhoA guanine nucleotide exchange factors (GEFs), in RhoA/ROCK signalling and DMD pathology was examined by generatingArhgef3knockoutmdxmice. The role of RhoA/ROCK signalling in mediating the function of ARHGEF3 was determined by evaluating the effects of wild‐type or GEF‐inactive ARHGEF3 overexpression with ROCK inhibitor treatment. To gain more mechanistic insights, autophagy flux and the role of autophagy were assessed in various conditions with chloroquine.

Results

Inhibition of ROCK with Y‐27632 improved muscle force production in 3D‐engineeredmdxmuscles (+25% from three independent experiments,P < 0.05) and in mice (+25%,P < 0.001). Unlike suggested by previous studies, this improvement was independent of muscle differentiation or quantity and instead related to increased muscle quality. We found that ARHGEF3 was elevated and responsible for RhoA/ROCK activation inmdxmuscles, and that depleting ARHGEF3 inmdxmice restored muscle quality (up to +36%,P < 0.01) and morphology without affecting regeneration. Conversely, overexpressing ARHGEF3 further compromisedmdxmuscle quality (−13% vs. empty vector control,P < 0.01) in GEF activity‐ and ROCK‐dependent manner. Notably, ARHGEF3/ROCK inhibition exerted the effects by rescuing autophagy which is commonly impaired in dystrophic muscles.

Conclusions

Our findings uncover a new pathological mechanism of muscle weakness in DMD involving the ARHGEF3‐ROCK‐autophagy pathway and the therapeutic potential of targeting ARHGEF3 in DMD.

 
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NSF-PAR ID:
10422435
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Journal of Cachexia, Sarcopenia and Muscle
Volume:
14
Issue:
4
ISSN:
2190-5991
Page Range / eLocation ID:
p. 1880-1893
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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