An atypical role for collapsin response mediator protein 2 (CRMP-2) in neurotransmitter release via interaction with presynaptic voltage-gated calcium channels.
Collapsin response mediator proteins (CRMPs) specify axon/dendrite fate and axonal growth of neurons through protein-protein interactions. Their functions in presynaptic biology remain unknown. Here, we identify the presynaptic N-type Ca(2+) channel (CaV2.2) as a CRMP-2-interacting protein. CRMP-2 binds directly to CaV2.2 in two regions: the channel domain I-II intracellular loop and the distal C terminus. Both proteins co-localize within presynaptic sites in hippocampal neurons. Overexpression in hippocampal neurons of a CRMP-2 protein fused to enhanced green fluorescent protein caused a significant increase in Ca(2+) channel current density, whereas lentivirus-mediated CRMP-2 knockdown abolished this effect. Interestingly, the increase in Ca(2+) current density was not due to a change in channel gating. Rather, cell surface biotinylation studies showed an increased number of CaV2.2 at the cell surface in CRMP-2-overexpressing neurons. These neurons also exhibited a significant increase in vesicular release in response to a depolarizing stimulus. Depolarization of CRMP-2-enhanced green fluorescent protein-overexpressing neurons elicited a significant increase in release of glutamate compared with control neurons. Toxin block of Ca(2+) entry via CaV2.2 abolished this stimulated release. Thus, the CRMP-2-Ca(2+) channel interaction represents a novel mechanism for modulation of Ca(2+) influx into nerve terminals and, hence, of synaptic strength.
Brittain
Joel M
JM
Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Piekarz
Andrew D
AD
Wang
Yuying
Y
Kondo
Takako
T
Cummins
Theodore R
TR
Khanna
Rajesh
R
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020864:Calcium Channels, N-Type / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D006624:Hippocampus / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission
C500963:Cacna1b protein, mouse; C503279:Cacna1b protein, rat; D020864:Calcium Channels, N-Type; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; C095114:collapsin response mediator protein-2; D002118:Calcium