RESEARCH ARTICLE The role of Pitx2 and Pitx3 in muscle stem cells gives new insights into P38a MAP kinase and redox regulation of muscle regeneration Aurore L’honore´ 1,2†*, Pierre-Henri Comme` re3, Elisa Negroni4, Giorgia Pallafacchina5, Bertrand Friguet2, Jacques Drouin6, Margaret Buckingham1, Didier Montarras1* 1Department of Developmental and Stem Cell Biology, CNRS, UMR 3738, Institut Pasteur, Paris, France; 2Biological Adaptation and Aging-IBPS, CNRS UMR 8256, INSERM ERL U1164, Sorbonne Universite´s, Universite´ Pierre et Marie Curie, Paris, France; 3Platform of Cytometry, Institut Pasteur, Paris, France; 4Center for Research in Myology, Sorbonne Universite´s, Universite´ Pierre et Marie Curie, Paris, France; 5NeuroscienceInstitute, Department of Biomedical Sciences, Italian National Research Council, Universityof Padova, Padova, Italy; 6Laboratory of Molecular Genetics, Institut de Recherches Cliniques de Montre´al, Montre´al, Canada Abstract Skeletal muscle regeneration depends on satellite cells. After injury these muscle stem *For correspondence: cells exit quiescence, proliferate and differentiate to regenerate damaged fibres. We show that this
[email protected] (AL’e´); progression is accompanied by metabolic changes leading to increased production of reactive
[email protected] (DM) oxygen species (ROS). Using Pitx2/3 single and double mutant mice that provide genetic models of Present address: †Sorbonne deregulated redox states, we demonstrate that moderate overproduction of ROS results in Universite´s, UPMC Universite´ premature differentiation of satellite cells while high levels lead to their senescence and Paris 06, Biological Adaptation regenerative failure. Using the ROS scavenger, N-Acetyl-Cysteine (NAC), in primary cultures we and Aging-IBPS, CNRS UMR show that a physiological increase in ROS is required for satellite cells to exit the cell cycle and 8256, INSERM ERL U1164, Paris, initiate differentiation through the redox activation of p38a MAP kinase.