Molecular Signatures of Membrane Protein Complexes Underlying Muscular Dystrophy

Abstract

Mutations in genes encoding components of the sarcolemmal dystrophin-glycoprotein complex (DGC) are responsible for a large number of muscular dystrophies. As such, molecular dissection of the DGC is expected to both reveal pathological mechanisms, and provides a biological framework for validating new DGC components. Establishment of the molecular composition of plasma-membrane protein complexes has been hampered by a lack of suitable biochemical approaches. Here we present an analytical workflow based upon the principles of protein correlation profiling that has enabled us to model the molecular composition of the DGC in mouse skeletal muscle. We also report our analysis of protein complexes in mice harboring mutations in DGC components. Bioinformatic analyses suggested that cell-adhesion pathways were under the transcriptional control of NFκB in DGC mutant mice, which is a finding that is supported by previous studies that showed NFκB-regulated pathways underlie the pathophysiology of DGC-related muscular dystrophies. Moreover, the bioinformatic analyses suggested that inflammatory and compensatory mechanisms were activated in skeletal muscle of DGC mutant mice. Additionally, this proteomic study provides a molecular framework to refine our understanding of the DGC, identification of protein biomarkers of neuromuscular disease, and pharmacological interrogation of the DGC in adult skeletal muscle https://www.mda.org/disease/congenital-muscular-dystrophy/research.

Emerging proteomic biomarkers of X-linked muscular dystrophy

“…Both, focused studies on the mass spectrometric identification and biochemical characterization of the dystrophin-glycoprotein complex, as well as systematic cataloguing studies of muscle tissue and cell lines, have been carried out over the last decade. A summary of major proteomic studies on dystrophin and the dystrophin complexome is provided in Table 1 [28][29][30][34][35][36][37][38][39][40][41][42][43][44][45].…”

“…Building on the initial biochemical characterization of the dystrophin complex by density gradient ultracentrifugation and chemical crosslinking analysis [32,46,47], proteomic studies could confirm the close linkage of dystrophin with the integral glycoprotein β-dystroglycan and its associated extracellular laminin-binding protein α-dystroglycan [34,[38][39][40][41][42][43][44][45]. Cortical actin, syntrophins, dystrobrevins, the α,β,γ,δsarcoglycan complex and laminin subunits are routinely identified by mass spectrometric surveys [28][29][30].…”

“…However, the integral protein sarcospan is often only identified by low sequence coverage using peptide mass spectrometry, even in highly enriched subcellular fractions from skeletal muscle [45], which is probably due to its low abundance and highly hydrophobic properties. Components of the wider dystrophin complex include caveolin, the desmoglein/desmoplakin complex, desmin, actinin, synemin, tubulins, vimentin and plectin on the intracellular side, and various collagen isoforms, fibronectin and biglycan on the extracellular side of muscle fibres [38][39][40][41][42][43][44] (Figure 4).…”

New insights in Tibial muscular dystrophy revealed by protein-protein interaction networks

“…This gene is related to the control of cell proliferation, survival and motility (Wee and Wang, 2017). In a study with mouse models of muscular dystrophy, it was shown that EGFR was up-regulated and was part of NFκBrelated protein complex, and it has been suggested that this NFκB-related protein complex, of which EGFR is part, is involved in the underlying pathophysiology of sarcolemmal dystrophin-glycoprotein complex-related muscular dystrophies (Turk et al, 2016), and that its overexpression is also related to a tumor-type that has failed to complete the myogenic program, the rhabdomyosarcoma (Ganti et al, 2006;Rao et al, 2010).…”

Detergents: Friends not foes for high‐performance membrane proteomics toward precision medicine

“…Several earlier proteomic studies applied digitonin to extract supercomplexes and/or to help fractionate protein lysates for native‐gel or gel‐free analyses, but they removed digitonin before protein digestion, using electrophoresis or buffer exchange into high urea or RapiGest . The 0.1% 0.81 mM digitonin (1.6–5× cmc) is similar to the 0.05% 1 mM DDM (∼5.9× cmc; cmc 0.17 mM in H 2 O) in molarity, and digitonin's chemical structure suggests potential tolerability/compatibility in the proteomic pipeline (protein solubilization, digestion, TMT labeling, and likely RP HPLC–MS/MS), possibly comparable to DDM.…”