RhoA mediates defective stem cell function and heterotopic ossification in dystrophic muscle of mice

Abstract

Heterotopic ossification (HO) and fatty infiltration (FI) often occur in diseased skeletal muscle and have been previously described in various animal models of Duchenne muscular dystrophy (DMD); however, the pathological mechanisms remain largely unknown. Dystrophin-deficient mdx mice and dystrophin/utrophin double-knockout (dKO) mice are mouse models of DMD; however, mdx mice display a strong muscle regeneration capacity, while dKO mice exhibit a much more severe phenotype, which is similar to patients with DMD. Our results revealed that more extensive HO, but not FI, occurred in the skeletal muscle of dKO mice versus mdx mice, and RhoA activation specifically occurred at the sites of HO. Moreover, the gene expression of RhoA, BMPs, and several inflammatory factors were significantly up-regulated in muscle stem cells isolated from dKO mice; while inactivation of RhoA in the cells with RhoA/ROCK inhibitor Y-27632 led to reduced osteogenic potential and improved myogenic potential. Finally, inactivation of RhoA signaling in the dKO mice with Y-27632 improved muscle regeneration and reduced the expression of BMPs, inflammation, HO, and intramyocellular lipid accumulation in both skeletal and cardiac muscle. Our results revealed that RhoA represents a major molecular switch in the regulation of HO and muscle regeneration in dystrophic skeletal muscle of mice.

Lysophosphatidic acid-induced RhoA signaling and prolonged macrophage infiltration worsens fibrosis and fatty infiltration following rotator cuff tears

“…Previous studies of the RhoA pathway in injured muscle have suggested that RhoA inhibition with small molecule inhibitors such as Y‐27632 leads to improved histologic outcomes compared to vehicle . Our current study contributes further to the literature by demonstrating that LPA‐induced inflammation and increased RhoA expression worsen muscle atrophy, fibrosis, and fatty infiltration following massive RC tears in rats.…”

“…The RhoA signaling pathway is regulated via G protein‐coupled receptors and is activated by the interaction between the receptors and ECM and/or soluble factors . RhoA activates RhoA kinase (ROCK) to increase turnover of the actin cytoskeleton and has been shown to contribute to monocyte transendothelial migration into tissue . Increased RhoA signaling has been reported in chronic muscle degeneration, such as muscular dystrophy .…”

Pathogenesis and prevention strategies of heterotopic ossification in total hip arthroplasty: a narrative literature review and results of a survey in Germany

“…HO was prevented in murine models by orally administering a nuclear, selective retinoic acid receptor c (RAR c) agonist (i.e. parovalotene), which suppresses BMP signalling and hence chondrogenesis [44,66,67]. Inhibitors of the ALK2 receptor (i.e.…”

The microRNA, miR-133b, functions to slow Duchenne muscular dystrophy pathogenesis

“…Prominent among genes upregulated in mdx; miR-133b -/muscle were a number of known miR-133b targets that were identified using miRTarBase [41] that have also been shown to be involved in TGF-B signaling and DMD pathology ( Table 1). These included RhoA, a well characterized target of miR-133b [42] that is associated with myoblast fusion, muscle regeneration, fatty infiltration and effectiveness of glucocorticoid treatment in mdx mice [43][44][45][46][47]. A number of other genes related to TGF-β signaling that are not presently known to be direct miR-133b targets were also upregulated in mdx; miR-133b -/muscle, including the TGF-β receptor, TGF-β-induced factor homeobox 1 (TGIF1), SMAD3, and SMAD5 (Table 2) [48,49].…”