title: Pathological pattern of Mdx mice diaphragm correlates with gradual expression of the short utrophin isoform Up71.
abstract: Utrophin gene is transcribed in a large mRNA of 13 kb that codes for a protein of 395 kDa. It shows amino acid identity with dystrophin of up to 73% and is widely expressed in muscle and non-muscle tissues. Up71 is a short utrophin product of the utrophin gene with the same cysteine-rich and C-terminal domains as full-length utrophin (Up395). Using RT-PCR, Western blots analysis, we demonstrated that Up71 is overexpressed in the mdx diaphragm, the most pathological muscle in dystrophin-deficient mdx mice, compared to wild-type C57BL/10 or other mdx skeletal muscles. Subsequently, we demonstrated that this isoform displayed an increased expression level up to 12 months, whereas full-length utrophin (Up395) decreased. In addition, beta-dystroglycan, the transmembrane glycoprotein that anchors the cytoplasmic C-terminal domain of utrophin, showed similar increase expression in mdx diaphragm, as opposed to other components of the dystrophin-associated protein complex (DAPC) such as alpha-dystrobrevin1 and alpha-sarcoglycan. We demonstrated that Up71 and beta-dystroglycan were progressively accumulated along the extrasynaptic region of regenerating clusters in mdx diaphragm. Our data provide novel functional insights into the pathological role of the Up71 isoform in dystrophinopathies.
authors.affiliation: Université Montpellier 1, UFR de Médecine, Laboratoire de Physiologie des Interactions, EA 701, Institut de Biologie, Boulevard Henri IV, 34062, Montpellier France
authors.forename: Karim
authors.initials: K
authors.lastname: Hnia
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tuffery-Giraud
authors.forename: Marianne
authors.initials: M
authors.lastname: Vermaelen
authors.forename: Gerald
authors.initials: G
authors.lastname: Hugon
authors.forename: Delphine
authors.initials: D
authors.lastname: Chazalette
authors.forename: Ahmed
authors.initials: A
authors.lastname: Masmoudi
authors.forename: François
authors.initials: F
authors.lastname: Rivier
authors.forename: Dominique
authors.initials: D
authors.lastname: Mornet
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D003893:Desmin / Q000378:metabolism; D003964:Diaphragm / Q000166:cytology / Q000378:metabolism / Q000473:pathology*; D049030:Dystroglycans / Q000378:metabolism; D005786:Gene Expression Regulation; D035002:Lower Extremity / Q000033:anatomy & histology; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D009136:Muscular Dystrophies / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D049411:Utrophin / Q000235:genetics / Q000378:metabolism*
chemical_list: D003893:Desmin; D020033:Protein Isoforms; D049411:Utrophin; D049030:Dystroglycans