title: Spatial distribution and molecular dynamics of dystrophin glycoprotein components at the neuromuscular junctionin vivo.
abstract: A bimolecular fluorescence complementation (BiFC) approach was used to study the molecular interactions between different components of the postsynaptic protein complex at the neuromuscular junction of living mice. We show that rapsyn forms complex with both α-dystrobrevin and α-syntrophin at the crests of junctional folds. The linkage of rapsyn to α-syntrophin and/or α-dystrobrevin is mediated by utrophin, a protein localized at acetylcholine receptor (AChR)-rich domains. In mice deficient in α-syntrophin, in which utrophin is no longer present at the synapse, rapsyn interaction with α-dystrobrevin was completely abolished. This interaction was completely restored when either utrophin or α-syntrophin was introduced into muscles deficient in α-syntrophin. However, in neuromuscular junctions deficient in α-dystrobrevin, in which utrophin is retained, complex formation between rapsyn and α-syntrophin was unaffected. Using fluorescence recovery after photobleaching, we found that α-syntrophin turnover is 5-7 times faster than that of AChRs, and loss of α-dystrobrevin has no effect on rapsyn and α-syntrophin half-life, whereas the half-life of AChR was significantly altered. Altogether, these results provide new insights into the spatial distribution of dystrophin glycoprotein components and their dynamics in living mice.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Aittaleb
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Isabel
authors.initials: I
authors.lastname: Martinez-Pena Y Valenzuela
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA makaabou@umich.edu.|College of Sciences and Engineering, Life Science Division, Hamad Bin Khalifa University, Doha, Qatar.
authors.forename: Mohammed
authors.identifier: 0000-0003-1991-0963
authors.initials: M
authors.lastname: Akaaboune
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D016189:Dystrophin / Q000737:chemistry* / Q000378:metabolism*; D049029:Dystrophin-Associated Proteins / Q000378:metabolism; D005260:Female; D005453:Fluorescence; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D056004:Molecular Dynamics Simulation; D009124:Muscle Proteins / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism*; D011485:Protein Binding; D013569:Synapses / Q000378:metabolism; D049411:Utrophin / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D016189:Dystrophin; D049029:Dystrophin-Associated Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; D049411:Utrophin; C098885:dystrobrevin; C051609:peripheral membrane protein 43K; C091825:syntrophin alpha1; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; C517672:Camk2b protein, mouse
keywords: AChR; DGC; Dystrophin glycoprotein complex; NMJ; Neuromuscular junction