Fig 1.

Overexpression of N1ICD promotes the self-renewal of satellite cells. (A) Experimental design. Results are based on Pax7-Cre^ER/Rosa-N1ICD mice, in which N1ICD^OE is induced by 4-OH-TAM and N1ICD^OE myoblasts coexpress nEGFP (nuclear localized GFP). Satellite cells undergo activation, proliferation, self-renewal, and differentiation while attached on their host myofibers. (B) Myoblast clusters on cultured single fibers were labeled with antibodies against Pax7, MyoD, and GFP. Nuclei were counterstained with 4′,6-diamidino-2-phenylindole (DAPI). Note that GFP marks the N1ICD^OE myoblasts. Dotted circles indicate the lack of MyoD staining in GFP⁺ cells. Bar, 20 μm. (C and D) Percentage of self-renewing (Pax7⁺ MyoD⁻) and proliferating (Pax7⁺ MyoD⁺) myobalsts in control and N1ICD^OE myoblast colonies (calculated from 28 cultured colonies in each group). (E) Percentage of self-renewing Pax7⁺ MyoD⁻ and proliferating Pax7⁺ MyoD⁺ myobalsts for GFP⁻ (∼30%) and GFP⁺ (∼70%) subpopulations among N1ICD^OE myoblast clusters (n = 28). (F) Number of myoblasts per cluster in control and N1ICD^OE myofiber cultures (n = 28).