Analysis of dysferlin and the formation of its protein tricomplex FAM65b-HDAC6-DYSF during the different phases of muscle differentiation

• Grant number: 22/02463-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): June 01, 2022
• Effective date (End): May 31, 2023
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Mariz Vainzof
• Grantee: Nathália Gagliardi Saldys
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 13/08028-1 - CEGH-CEL - Human Genome and Stem Cell Research Center, AP.CEPID

Abstract

Skeletal muscle is a post-mitotic tissue formed from myogenic progenitor cells that originate the myoblasts, which proliferate, differentiate and fuse, forming myotubes. Recessive Limb Girdle Muscular Dystrophy 2 (DMC2R) is caused by mutations in the DYSF gene, which encodes the dysferlin protein, causing muscle degeneration and weakness and poor regeneration. Recent studies have shown that dysferlin transiently binds to HDAC6 and FAM65b proteins, forming an important protein tricomplex during muscle regeneration. In the proliferation stage, the HDAC6 protein deacetylates the ±-tubulin protein, depolymerizing the microtubules, allowing the proliferation and maintenance of undifferentiated myoblasts. With the induction of differentiation, the expression of dysferlin and FAM65b is increased, and with the association of HDAC6, form the tricomplex. This prevents the action of HDAC6 on ±-tubulin, allowing the polymerization of microtubules, fusion and elongation of the myotubes. The discovery of this protein tricomplex is recent and there are still no specific studies on its expression throughout all stages of muscle differentiation. Therefore, this project aims to analyze in more detail the formation of the tricomplex and its role in the myogenic development. We will use immortalized normal human myoblasts that follow a well-characterized pattern of muscle differentiation. The expression of the tricomplex will be studied at the mRNA and protein levels in the different stages of differentiation, and its formation will be evaluated using co-immunoprecipitation experiments. This project is extremely relevant, contributing to the elucidation of the cause of the deficient regeneration process in muscles of patients with DMC2R, and may help to identify new therapeutic targets.(AU)