Analysis of the expression of different forms of myosin in vitro in myogenesis process in cellular models for neuromuscular diseases

Abstract

Skeletal muscle is composed of muscle fibers that are multinucleated and elongated structures. During myogenesis, undifferentiated mononuclear cells, the myoblasts, proliferate and fuse, forming myotubes, differentiated multinucleated cells. In mature myotubes, proteins such as actin and myosin, protagonists in muscle contraction, are expressed. Different forms of myosins are expressed in human skeletal muscle, according to the gene that codes them. Developmental myosin and neonatal myosin are heavy chain forms that are highly expressed in early differentiation and in regeneration processes. In mature muscles, the fast and slow myosin forms are more expressed. In a recent study from our laboratory, we found that myoblasts originated from a patient with X-linked Myopathy with excessive autophagy (XMEA) had a high fusogenic capacity, forming large myotubes, which was not related to down regulation of myogenic factors. However, the expression and participation of myosins during myogenesis in the XMEA cell line and in other muscle cell lines have not been studied yet. Thus, this project aims to study muscle development in vitro, using myoblasts from XMEA patients and comparing them to myoblasts from normal individuals and from patients with Duchenne Dystrophy (DMD). The expression of heavy chain myosins at different stages of differentiation will be evaluated, as well as the proteins acting directly on the myoblast fusion process. In addition, the role of the VMA21 gene in exacerbated myogenesis in XMEA will be evaluated through its silencing in normal muscle cell lines.(AU)