MuSK is required for anchoring acetylcholinesterase at the neuromuscular junction.
At the neuromuscular junction, acetylcholinesterase (AChE) is mainly present as asymmetric forms in which tetramers of catalytic subunits are associated to a specific collagen, collagen Q (ColQ). The accumulation of the enzyme in the synaptic basal lamina strictly relies on ColQ. This has been shown to be mediated by interaction between ColQ and perlecan, which itself binds dystroglycan. Here, using transfected mutants of ColQ in a ColQ-deficient muscle cell line or COS-7 cells, we report that ColQ clusterizes through a more complex mechanism. This process requires two heparin-binding sites contained in the collagen domain as well as the COOH terminus of ColQ. Cross-linking and immunoprecipitation experiments in Torpedo postsynaptic membranes together with transfection experiments with muscle-specific kinase (MuSK) constructs in MuSK-deficient myotubes or COS-7 cells provide the first evidence that ColQ binds MuSK. Together, our data suggest that a ternary complex containing ColQ, perlecan, and MuSK is required for AChE clustering and support the notion that MuSK dictates AChE synaptic localization at the neuromuscular junction.
Cartaud
Annie
A
Biologie Cellulaire des Membranes, Institut Jacques Monod, UMR 7592 Centre National de la Recherche Scientifique (CNRS), Universités Paris 6 and Paris 7, 75251 Paris, Cedex 05, France.
Strochlic
Laure
L
Guerra
Manuel
M
Blanchard
Benoît
B
Lambergeon
Monique
M
Krejci
Eric
E
Cartaud
Jean
J
Legay
Claire
C
D000110:Acetylcholinesterase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D018345:Mice, Knockout; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000201:enzymology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009469:Neuromuscular Junction / Q000201:enzymology* / Q000648:ultrastructure; D011485:Protein Binding / Q000235:genetics; D011940:Receptor Aggregation / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*; D013570:Synaptic Membranes / Q000201:enzymology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000235:genetics; D014162:Transfection
D019812:Heparan Sulfate Proteoglycans; D046911:Macromolecular Substances; D009124:Muscle Proteins; D011950:Receptors, Cholinergic; C071927:perlecan; D003094:Collagen; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D000110:Acetylcholinesterase; C114027:COLQ protein, human