title: Cloning and characterization of muscle-specific kinase in chicken.
abstract: Muscle-specific kinase (MuSK) is part of the receptor complex that is involved in the agrin-induced formation of the neuromuscular junction. In the rodent, prominent mRNA expression of MuSK is restricted to skeletal muscle while the expression of agrin can also be detected in brain and certain nonneuronal tissues. The recent identification of Xenopus MuSK reveals that MuSK can be detected in tissues other than skeletal muscle, such as the neural tube, eye vesicles, and spleen. In this study, we describe the cloning and characterization of the chicken ortholog of MuSK and demonstrate that the regulation of MuSK expression in muscle is conserved from avian to rodent. Abundant mRNA expression of MuSK can be detected in early embryonic chick muscle and is up-regulated after nerve injury. More importantly, we also demonstrate that, in the chicken, MuSK mRNA is expressed during development in brain and liver, suggesting possible novel functions for MuSK. Furthermore, the regulatory profile of MuSK expression in chick muscle closely parallels that observed for acetylcholine receptor, in terms of both mRNA expression and protein localization. Finally, studies with paralyzed chicken muscle as well as with cultured chick myotubes demonstrate the dependence of MuSK on both electrical activity and trophic factors.
authors.affiliation: Department of Biochemistry and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
authors.forename: F C
authors.initials: FC
authors.lastname: Ip
authors.forename: D G
authors.initials: DG
authors.lastname: Glass
authors.forename: D R
authors.initials: DR
authors.lastname: Gies
authors.forename: J
authors.initials: J
authors.lastname: Cheung
authors.forename: K O
authors.initials: KO
authors.lastname: Lai
authors.forename: A K
authors.initials: AK
authors.lastname: Fu
authors.forename: G D
authors.initials: GD
authors.lastname: Yancopoulos
authors.forename: N Y
authors.initials: NY
authors.lastname: Ip
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D009121:Muscle Denervation; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000201:enzymology; D018482:Muscle, Skeletal / Q000166:cytology / Q000201:enzymology / Q000294:innervation; D009409:Nerve Crush; D010243:Paralysis / Q000139:chemically induced; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics*; D011950:Receptors, Cholinergic; D012584:Sciatic Nerve / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013779:Tetrodotoxin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D011950:Receptors, Cholinergic; D013779:Tetrodotoxin; C095714:MUSK protein, human; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases