Mislocalisation of Pax7 and Its Interaction with Importin-α1 (KPNA2) in Dystrophin-Deficient Myoblasts

Abstract

Background: Pax 7 is one of the key factors in the development of tissues and organs during embryogenesis. It has been suggested that Pax7 may play a major role during myogenesis. Our previous study has shown that Pax7 cell is attenuated in the mdx embryo during gestation as well as in dystrophic muscle indicating that an absence of dystrophin in muscle affects pax7 regulation in Duchene Muscular Dystrophy (DMD). Therefore, we aimed to investigate the Pax7 expression pattern as well as their specific transport protein in dystrophin-deficient myoblasts at postnatal/juvenile stage. Methods: In this study, dfd13 (dystrophin-deficient) and C2C12 (non-dystrophic) myoblasts were cultured under normal conditions prior to further analyse its expression pattern at proliferating stage via western blot and immunofluorescence analysis. Protein prediction and protein interaction study was done via in silico and co-immunoprecipitation analyses, respectively.Results: It was found that Pax7 localised in the cytoplasm of dystrophin-deficient myoblasts and high expression retained during differentiation. Co-localisation analysis of Pax7 with subcellular markers indicated that Pax7 is highly synthesised at their proliferative state. Interestingly, it is shown that Pax7 possess a nuclear location signal and KPNA2 was suggested as an escort protein for Pax7 translocation into the nucleus. Conclusion: For the first time, our study showed that Pax7 is mislocalised in dystrophin-deficient myoblasts and it is postulated that KPNA2 is the karyopherin-α which might be responsible for Pax7 translocation into the nucleus.

PAX7, a Key for Myogenesis Modulation in Muscular Dystrophies through Multiple Signaling Pathways: A Systematic Review

“…Pax7 is a transcription factor known to be indispensable in myogenesis by modulating MyoD expression and maintaining healthy and mature cell differentiation [15,16]. Pax7 belongs to the highly conserved paired-box (Pax) gene family transcription factor and is critically expressed during the development of the nervous and muscular systems [17]. Interestingly, it has been revealed that overexpression of Pax7 regulates myogenic differentiation by downregulating MyoD expression and prevents MyoG induction in fetal Duchenne Muscular Dystrophy (DMD) muscle tissues, suggesting a delay in myofibers differentiation program [18,19].…”