Transcriptomic analysis of differentiated myoblasts

Adult skeletal muscle is a plastic tissue that can adapt its size to workload. Here, we show that RhoA within myofibers is needed for overload-induced hypertrophy by controlling satellite cell fusion to the growing myofibers without affecting protein synthesis. At the molecular level, we demonstrate that, in response to increased workload, RhoA controls in a cell autonomous manner Erk1/2 activation and the expressions of extracellular matrix (ECM) regulators such as Mmp9/Mmp13/Adam8 and of macrophage chemo-attractants such as Ccl3/Cx3cl1. Their decreased expression in RhoA mutant is associated with ECM and fibrillar collagen disorganization and lower macrophage infiltration. Moreover, Mmps inhibition and macrophage depletion in controls phenocopied the lack of growth of RhoA mutants. These findings unravel the implication of RhoA within myofibers, in response to increase load, in the building of a permissive microenvironment for muscle growth and for satellite cell accretion through ECM remodeling and inflammatory cell recruitment. The aim of the analysis is to compare myotubes controls and myotubes lacking RhoA. Primary myoblast were isolated by RhoAfloxed mice by FACS. The cells isolated by FACS, proliferate and differentiate in culture. The differentiated myotubes were transduced with Adeno-mcherry or Adeno-cre-mcherry adenoviruses in order to delete RhoA ex vivo. RhoA deletion occurs ex vivo once that the myotubes are formed in order to mimic the deletion that occurs in vivo in adult myofibers. RNA was isolated from primary differentiated myoblasts transduced with Adeno-mcherry or Adeno-cre-mcherry adenovirus. Microarray analysis will help to understand the molecular pathways involved in fusion defect observed in vivo. Isolated RNA from 4 myotubes transduced with Adeno mcherry and from 4 myotubes transduced with Adeno-cre-mcherry were used to perform trasncriptomic arrays.