Expression levels of the dystrophin associated protein complex components is DMD gene mutation type dependent.


Pre-Clinical Research

Poster Number: 228


Emily Canessa, BS, Binghamton University, Ahmed Naveed, Binghamton University, Jade Tiszler, Binghamton University, Steven Mckay, Binghamton University, Luca Bello, PhD, University of Padova, Elena Pegoraro, PhD, University of Padova, Yetrib Hathout, PhD, Binghamton University

The dystrophin associated protein complex (DAPC) is an important and multifaceted glycoprotein complex located in the sarcolemma of muscle fibers. The complex is comprised of several transmembrane proteins that function as an anchoring point, intracellular peripheral proteins with signaling mechanisms, and extracellular sub-complexes that connect the DAPC to the extracellular matrix. Central to this complex is the dystrophin protein, which under normal conditions connects the intracellular actin cytoskeleton of the myofiber to the DAPC, and subsequently to the laminin-rich extracellular matrix. In Duchenne muscular dystrophy (DMD), out-of-frame mutations result in the complete loss of dystrophin expression in muscle tissue, while in Becker muscular dystrophy (BMD) in-frame mutations result in truncated version of the protein being produced. By using targeted mass spectrometry to accurately quantify members of the DAPC in muscle tissue, we demonstrate that specific mutations in the DMD gene differentially impacted the expression levels and the stoichiometry of the DAPC components. Out-of-frame mutations in DMD resulted in a dramatic decrease in the expression levels of all DAPC components except for laminin-alpha 2, which was moderately decreased. Interestingly, in-frame-mutations in the proximal parts of the DMD gene (e.g., del 2-7) showed remarkable increase in the expression levels of the DAPC components compared to distal mutations (e.g., del 45-51) in BMD patients. The type of mutations in the DMD gene and their impact on DAPC components could explain the heterogeneity of disease severity seen in BMD patients. This should help guide dystrophin replacement therapies such as exon skipping and gene therapy.