title: Mutations in the C-terminal domain of ColQ in endplate acetylcholinesterase deficiency compromise ColQ-MuSK interaction.
abstract: Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is mostly composed of an asymmetric form in which three tetramers of catalytic AChE subunits are linked to a triple helical collagen Q (ColQ). Mutations in COLQ cause endplate AChE deficiency. We report three patients with endplate AChE deficiency with five recessive COLQ mutations. Sedimentation profiles showed that p.Val322Asp and p.Arg227X, but not p.Cys444Tyr, p.Asp447His, or p.Arg452Cys, inhibit formation of triple helical ColQ. In vitro overlay of mutant ColQ-tailed AChE on muscle sections of Colq(-/-) mice revealed that p.Cys444Tyr, p.Asp447His, and p.Arg452Cys in the C-terminal domain (CTD) abrogate anchoring ColQ-tailed AChE to the NMJ. In vitro plate-binding assay similarly demonstrated that the three mutants inhibit binding of ColQ-tailed AChE to MuSK. We also confirmed the pathogenicity of p.Asp447His by treating Colq(-/-) mice with adeno-associated virus serotype 8 carrying mutant COLQ-p.Asp447His. The treated mice showed no improvement in motor functions and no anchoring of ColQ-tailed AChE at the NMJ. Electroporation of mutant COLQ harboring p.Cys444Tyr, p.Asp447His, and p.Arg452Cys into anterior tibial muscles of Colq(-/-) mice similarly failed to anchor ColQ-tailed AChE at the NMJ. We proved that the missense mutations in ColQ-CTD cause endplate AChE deficiency by compromising ColQ-MuSK interaction at the NMJ.
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakata
authors.forename: Mikako
authors.initials: M
authors.lastname: Ito
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Azuma
authors.forename: Kenji
authors.initials: K
authors.lastname: Otsuka
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Noguchi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Komaki
authors.forename: Akihisa
authors.initials: A
authors.lastname: Okumura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Akio
authors.initials: A
authors.lastname: Masuda
authors.forename: Jun
authors.initials: J
authors.lastname: Natsume
authors.forename: Seiji
authors.initials: S
authors.lastname: Kojima
authors.forename: Kinji
authors.initials: K
authors.lastname: Ohno
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000818:Animals; D019556:COS Cells; D002648:Child; D002522:Chlorocebus aethiops; D003094:Collagen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D020294:Myasthenic Syndromes, Congenital / Q000235:genetics* / Q000503:physiopathology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D055815:Young Adult
chemical_list: D009124:Muscle Proteins; D011950:Receptors, Cholinergic; D003094:Collagen; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D000110:Acetylcholinesterase; C114027:COLQ protein, human