A presynaptic giant ankyrin stabilizes the NMJ through regulation of presynaptic microtubules and transsynaptic cell adhesion.
In a forward genetic screen for mutations that destabilize the neuromuscular junction, we identified a novel long isoform of Drosophila ankyrin2 (ank2-L). We demonstrate that loss of presynaptic Ank2-L not only causes synapse disassembly and retraction but also disrupts neuronal excitability and NMJ morphology. We provide genetic evidence that ank2-L is necessary to generate the membrane constrictions that normally separate individual synaptic boutons and is necessary to achieve the normal spacing of subsynaptic protein domains, including the normal organization of synaptic cell adhesion molecules. Mechanistically, synapse organization is correlated with a lattice-like organization of Ank2-L, visualized using extended high-resolution structured-illumination microscopy. The stabilizing functions of Ank2-L can be mapped to the extended C-terminal domain that we demonstrate can directly bind and organize synaptic microtubules. We propose that a presynaptic Ank2-L lattice links synaptic membrane proteins and spectrin to the underlying microtubule cytoskeleton to organize and stabilize the presynaptic terminal.
Pielage
Jan
J
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158-2822, USA.
Cheng
Ling
L
Fetter
Richard D
RD
Carlton
Pete M
PM
Sedat
John W
JW
Davis
Graeme W
GW
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D017487:Ankyrins / Q000235:genetics*; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D006735:Horseradish Peroxidase / Q000378:metabolism; D007814:Larva; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009469:Neuromuscular Junction / Q000502:physiology* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D016704:Synapsins / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics
C498993:Ank2 protein, Drosophila; D017487:Ankyrins; D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D008164:Luminescent Proteins; D016704:Synapsins; C051642:fasciclin II; D006735:Horseradish Peroxidase