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Published on: May 7, 2020
Molecular Fingerprint of BMD Patients Lacking a Portion in the Rod Domain of Dystrophin
Daniele Capitanio1, Manuela Moriggi2, Pietro Barbacini1
1Department of Biomedical Sciences for Health, University of Milan, 20054 Segrate, Italy.
Abstract:
BMD is characterized by a marked heterogeneity of gene mutations resulting in many abnormal dystrophin proteins with different expression and residual functions. The smaller dystrophin molecules lacking a portion around exon 48 of the rod domain, named the D8 region, are related to milder phenotypes. The study aimed to determine which proteins might contribute to preserving muscle function in these patients. Patients were subdivided, based on the absence or presence of deletions in the D8 region, into two groups, BMD1 and BMD2. Muscle extracts were analyzed by 2-D DIGE, label-free LC-ESI-MS/MS, and Ingenuity pathway analysis (IPA). Increased levels of proteins typical of fast fibers and of proteins involved in the sarcomere reorganization characterize BMD2. IPA of proteomics datasets indicated in BMD2 prevalence of glycolysis and gluconeogenesis and a correct flux through the TCA cycle enabling them to maintain both metabolism and epithelial adherens junction. A 2-D DIGE analysis revealed an increase of acetylated proteoforms of moonlighting proteins aldolase, enolase, and glyceraldehyde-3-phosphate dehydrogenase that can target the nucleus promoting stem cell recruitment and muscle regeneration. In BMD2, immunoblotting indicated higher levels of myogenin and lower levels of PAX7 and SIRT1/2 associated with a set of proteins identified by proteomics as involved in muscle homeostasis maintenance.
Insights
Duchenne muscular dystrophy (BMD) patients with specific gene deletions (D8 region) show milder symptoms. These patients exhibit enhanced muscle metabolism and regeneration pathways, suggesting potential therapeutic targets for preserving muscle function.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Duchenne muscular dystrophy (BMD) presents diverse genetic mutations leading to abnormal dystrophin proteins.
- Smaller dystrophin variants lacking the D8 region correlate with milder clinical phenotypes.
Purpose of the Study:
- To identify proteins contributing to preserved muscle function in BMD patients with D8 region deletions.
- To compare protein profiles between BMD patients with and without D8 region deletions (BMD1 vs. BMD2).
Main Methods:
- Proteomic analysis using 2-D DIGE and label-free LC-ESI-MS/MS.
- Bioinformatic analysis with Ingenuity Pathway Analysis (IPA).
- Immunoblotting for specific protein markers (myogenin, PAX7, SIRT1/2).
Main Results:
- BMD2 patients (with D8 deletions) showed increased fast-fiber proteins and sarcomere reorganization.
- IPA revealed enhanced glycolysis, gluconeogenesis, and TCA cycle flux in BMD2.
- Increased acetylated moonlighting proteins (aldolase, enolase, GAPDH) linked to stem cell recruitment and regeneration were observed in BMD2.
Conclusions:
- BMD2 patients exhibit distinct proteomic profiles supporting preserved muscle metabolism and regeneration.
- Specific protein alterations, including moonlighting proteins and muscle homeostasis factors, contribute to milder BMD phenotypes.
- Findings suggest novel therapeutic strategies targeting metabolic and regenerative pathways in BMD.
