title: Specific proteolytic cleavage of agrin regulates maturation of the neuromuscular junction.
abstract: During the initial stage of neuromuscular junction (NMJ) formation, nerve-derived agrin cooperates with muscle-autonomous mechanisms in the organization and stabilization of a plaque-like postsynaptic specialization at the site of nerve-muscle contact. Subsequent NMJ maturation to the characteristic pretzel-like appearance requires extensive structural reorganization. We found that the progress of plaque-to-pretzel maturation is regulated by agrin. Excessive cleavage of agrin via transgenic overexpression of an agrin-cleaving protease, neurotrypsin, in motoneurons resulted in excessive reorganizational activity of the NMJs, leading to rapid dispersal of the synaptic specialization. By contrast, expression of cleavage-resistant agrin in motoneurons slowed down NMJ remodeling and delayed NMJ maturation. Neurotrypsin, which is the sole agrin-cleaving protease in the CNS, was excluded as the physiological agrin-cleaving protease at the NMJ, because NMJ maturation was normal in neurotrypsin-deficient mice. Together, our analyses characterize agrin cleavage at its proteolytic α- and β-sites by an as-yet-unspecified protease as a regulatory access for relieving the agrin-dependent constraint on endplate reorganization during NMJ maturation.
authors.affiliation: Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Marc F
authors.initials: MF
authors.lastname: Bolliger
authors.forename: Andreas
authors.initials: A
authors.lastname: Zurlinden
authors.forename: Daniel
authors.initials: D
authors.lastname: Lüscher
authors.forename: Lukas
authors.initials: L
authors.lastname: Bütikofer
authors.forename: Olga
authors.initials: O
authors.lastname: Shakhova
authors.forename: Maura
authors.initials: M
authors.lastname: Francolini
authors.forename: Serguei V
authors.initials: SV
authors.lastname: Kozlov
authors.forename: Paolo
authors.initials: P
authors.lastname: Cinelli
authors.forename: Alexander
authors.initials: A
authors.lastname: Stephan
authors.forename: Andreas D
authors.initials: AD
authors.lastname: Kistler
authors.forename: Thomas
authors.initials: T
authors.lastname: Rülicke
authors.forename: Pawel
authors.initials: P
authors.lastname: Pelczar
authors.forename: Birgit
authors.initials: B
authors.lastname: Ledermann
authors.forename: Guido
authors.initials: G
authors.lastname: Fumagalli
authors.forename: Sergio M
authors.initials: SM
authors.lastname: Gloor
authors.forename: Beat
authors.initials: B
authors.lastname: Kunz
authors.forename: Peter
authors.initials: P
authors.lastname: Sonderegger
mesh_terms: D018171:Agrin / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000378:metabolism; D009412:Nerve Fibers / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D018171:Agrin; D012697:Serine Endopeptidases; C108493:neurotrypsin