title: Impaired viability of muscle precursor cells in muscular dystrophy with glycosylation defects and amelioration of its severe phenotype by limited gene expression.
abstract: A group of muscular dystrophies, dystroglycanopathy is caused by abnormalities in post-translational modifications of dystroglycan (DG). To understand better the pathophysiological roles of DG modification and to establish effective clinical treatment for dystroglycanopathy, we here generated two distinct conditional knock-out (cKO) mice for fukutin, the first dystroglycanopathy gene identified for Fukuyama congenital muscular dystrophy. The first dystroglycanopathy model-myofiber-selective fukutin-cKO [muscle creatine kinase (MCK)-fukutin-cKO] mice-showed mild muscular dystrophy. Forced exercise experiments in presymptomatic MCK-fukutin-cKO mice revealed that myofiber membrane fragility triggered disease manifestation. The second dystroglycanopathy model-muscle precursor cell (MPC)-selective cKO (Myf5-fukutin-cKO) mice-exhibited more severe phenotypes of muscular dystrophy. Using an isolated MPC culture system, we demonstrated, for the first time, that defects in the fukutin-dependent modification of DG lead to impairment of MPC proliferation, differentiation and muscle regeneration. These results suggest that impaired MPC viability contributes to the pathology of dystroglycanopathy. Since our data suggested that frequent cycles of myofiber degeneration/regeneration accelerate substantial and/or functional loss of MPC, we expected that protection from disease-triggering myofiber degeneration provides therapeutic effects even in mouse models with MPC defects; therefore, we restored fukutin expression in myofibers. Adeno-associated virus (AAV)-mediated rescue of fukutin expression that was limited in myofibers successfully ameliorated the severe pathology even after disease progression. In addition, compared with other gene therapy studies, considerably low AAV titers were associated with therapeutic effects. Together, our findings indicated that fukutin-deficient dystroglycanopathy is a regeneration-defective disorder, and gene therapy is a feasible treatment for the wide range of dystroglycanopathy even after disease progression.
authors.affiliation: Division of Neurology/Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Kanagawa
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Yu
authors.forename: Chiyomi
authors.initials: C
authors.lastname: Ito
authors.forename: So-ichiro
authors.initials: S
authors.lastname: Fukada
authors.forename: Masako
authors.initials: M
authors.lastname: Hozoji-Inada
authors.forename: Tomoko
authors.initials: T
authors.lastname: Chiyo
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kuga
authors.forename: Megumi
authors.initials: M
authors.lastname: Matsuo
authors.forename: Kanoko
authors.initials: K
authors.lastname: Sato
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Takahito
authors.initials: T
authors.lastname: Ito
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Ohtsuka
authors.forename: Yuki
authors.initials: Y
authors.lastname: Katanosaka
authors.forename: Yuko
authors.initials: Y
authors.lastname: Miyagoe-Suzuki
authors.forename: Keiji
authors.initials: K
authors.lastname: Naruse
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.forename: Shin'ichi
authors.initials: S
authors.lastname: Takeda
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Toda
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000235:genetics; D004195:Disease Models, Animal; D049030:Dystroglycans / Q000378:metabolism*; D015870:Gene Expression; D006031:Glycosylation; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009136:Muscular Dystrophies / Q000235:genetics* / Q000378:metabolism*; D032446:Myoblasts / Q000378:metabolism*; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics; D010641:Phenotype; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D014166:Transferases
chemical_list: D051787:Myogenic Regulatory Factor 5; D011506:Proteins; D049030:Dystroglycans; C491879:Fcmd protein, mouse; D014166:Transferases