Satellite cells (SCs) are adult muscle stem cells that are recruited when muscle homeostasis is disturbed. The RhoA GTPase is an important signalling enzyme involved in the rearrangement of the actin cytoskeleton and in the differentiation of myoblast lines.
A team from the Institut Cochin in collaboration with researchers from the Institute’s Myology Research Centre demonstrated that :
- the presence of RhoA in SCs is crucial for correct muscle regeneration and hypertrophy :
. in a regeneration context, the absence of RhoA in SCs prevents proper fusion of SCs with other RhoA-deficient SCs
. in the context of hypertrophy, the absence of RhoA in SCs prevents correct fusion of SCs with growing control myofibres
- if RhoA is dispensable for the proliferation and differentiation of SCs :
. RhoA-depleted SCs have an inefficient movement even if the assembly of their cytoskeleton is not altered,
. proliferative myoblasts and differentiated myotubes lacking RhoA show reduced expression of Chordin (an important negative regulator of BMP activity), suggesting an interaction between these genes in the regulation of myoblast fusion.
These results highlight the importance of RhoA in the regulation of SC fusion and its necessity for effective restoration of skeletal muscle homeostasis.
