TY - JOUR
T1 - Aberrant neuromuscular junctions and delayed terminal muscle fiber maturation in α-dystroglycanopathies
AU - Taniguchi, Mariko
AU - Kurahashi, Hiroki
AU - Noguchi, Satoru
AU - Fukudome, Takayasu
AU - Okinaga, Takeshi
AU - Tsukahara, Toshifumi
AU - Tajima, Youichi
AU - Ozono, Keiichi
AU - Nishino, Ichizo
AU - Nonaka, Ikuya
AU - Toda, Tatsushi
N1 - Funding Information:
We are grateful to Drs Fumiaki Saito and Shin’ichi Takeda for their critical comments, Fumie Uematsu and Eiji Oiki for technical support and Dr Jennifer Logan for editing the manuscript. This work was supported by a Health Science Research Grant, Research on Psychiatric and Neurological Diseases and Mental Health, from the Ministry of Health, Labor, and Welfare of Japan; and by the 21st Century COE program from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
PY - 2006/4
Y1 - 2006/4
N2 - Recent studies have revealed an association between post-translational modification of α-dystroglycan (α-DG) and certain congenital muscular dystrophies known as secondary α-dystroglycanopathies (α-DGpathies). Fukuyama-type congenital muscular dystrophy (FCMD) is classified as a secondary α-DGpathy because the responsible gene, fukutin, is a putative glycosyltransferase for α-DG. To investigate the pathophysiology of secondary α-DGpathies, we profiled gene expression in skeletal muscle from FCMD patients. cDNA microarray analysis and quantitative real-time polymerase chain reaction showed that expression of developmentally regulated genes, including myosin heavy chain (MYH) and myogenic transcription factors (MRF4, myogenin and MyoD), in FCMD muscle fibers is inconsistent with dystrophy and active muscle regeneration, instead more of implicating maturational arrest. FCMD skeletal muscle contained mainly immature type 2C fibers positive for immature-type MYH. These characteristics are distinct from Duchenne muscular dystrophy, suggesting that another mechanism in addition to dystrophy accounts for the FCMD skeletal muscle lesion. Immunohistochemical analysis revealed morphologically aberrant neuromuscular junctions (NMJs) lacking MRF4 co-localization. Hypoglycosylated α-DG indicated a lack of aggregation, and acetylcholine receptor (AChR) clustering was compromised in FCMD and the myodystrophy mouse, another model of secondary α-DGpathy. Electron microscopy showed aberrant NMJs and neural terminals, as well as myotubes with maturational defects. Functional analysis of NMJs of α-DGpathy showed decreased miniature endplate potential and higher sensitivities to d-Tubocurarine, suggesting aberrant or collapsed formation of NMJs. Because α-DG aggregation and subsequent clustering of AChR are crucial for NMJ formation, hypoglycosylation of α-DG results in aberrant NMJ formation and delayed muscle terminal maturation in secondary α-DGpathies. Although severe necrotic degeneration or wasting of skeletal muscle fibers is the main cause of congenital muscular dystrophies, maturational delay of muscle fibers also underlies the etiology of secondary α-DGpathies.
AB - Recent studies have revealed an association between post-translational modification of α-dystroglycan (α-DG) and certain congenital muscular dystrophies known as secondary α-dystroglycanopathies (α-DGpathies). Fukuyama-type congenital muscular dystrophy (FCMD) is classified as a secondary α-DGpathy because the responsible gene, fukutin, is a putative glycosyltransferase for α-DG. To investigate the pathophysiology of secondary α-DGpathies, we profiled gene expression in skeletal muscle from FCMD patients. cDNA microarray analysis and quantitative real-time polymerase chain reaction showed that expression of developmentally regulated genes, including myosin heavy chain (MYH) and myogenic transcription factors (MRF4, myogenin and MyoD), in FCMD muscle fibers is inconsistent with dystrophy and active muscle regeneration, instead more of implicating maturational arrest. FCMD skeletal muscle contained mainly immature type 2C fibers positive for immature-type MYH. These characteristics are distinct from Duchenne muscular dystrophy, suggesting that another mechanism in addition to dystrophy accounts for the FCMD skeletal muscle lesion. Immunohistochemical analysis revealed morphologically aberrant neuromuscular junctions (NMJs) lacking MRF4 co-localization. Hypoglycosylated α-DG indicated a lack of aggregation, and acetylcholine receptor (AChR) clustering was compromised in FCMD and the myodystrophy mouse, another model of secondary α-DGpathy. Electron microscopy showed aberrant NMJs and neural terminals, as well as myotubes with maturational defects. Functional analysis of NMJs of α-DGpathy showed decreased miniature endplate potential and higher sensitivities to d-Tubocurarine, suggesting aberrant or collapsed formation of NMJs. Because α-DG aggregation and subsequent clustering of AChR are crucial for NMJ formation, hypoglycosylation of α-DG results in aberrant NMJ formation and delayed muscle terminal maturation in secondary α-DGpathies. Although severe necrotic degeneration or wasting of skeletal muscle fibers is the main cause of congenital muscular dystrophies, maturational delay of muscle fibers also underlies the etiology of secondary α-DGpathies.
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U2 - 10.1093/hmg/ddl045
DO - 10.1093/hmg/ddl045
M3 - Article
C2 - 16531417
AN - SCOPUS:33645806539
SN - 0964-6906
VL - 15
SP - 1279
EP - 1289
JO - Human molecular genetics
JF - Human molecular genetics
IS - 8
ER -