|Synapse maintenance is important for the preservation of neuronal circuitry and normal behavior. Cysteine string protein α (CSPα) is one of the few presynaptic proteins known to participate in synapse maintenance. Deletion of CSPα, a co-chaperone for Hsc70, leads to impairment in local protein homeostasis resulting in synaptic dysfunction as well as synapse and neuronal loss. Here, we sought to identify the repertoire of CSPα clients with the aim of understanding the CSPα's role in synapse function and stability. Based on the rationale that CSPα clients are misfolded in CSPα knockout (KO) and thereby decreased in at synapses, we utilized unbiased proteomic methods to compare the synaptic proteome of littermate wildtype
and CSPα KO mice. Using this strategy, we identified and validated that the levels of 19 synaptic proteins were selectively decreased in CSPα KO synapses. By performing a secondary screen with these proteins for direct binding to CSPα, we identified 2 key CSPα clients. They are SNAP-25, a previously identified client of CSPα, and dynamin 1, the GTPase that regulates synaptic vesicle fission. Using hippocampal cultures derived from CSPα KO mice, we show that
CSPα regulates the stability of both SNAP-25 and dynamin 1. We then investigated CSPα's interaction with dynamin 1. Our analysis revealed that CSPα regulates the polymerization of dynamin1 and thereby synaptic vesicle endocytosis. Our data provide mechanistic insight into the dual functions of CSPα in both the exo- and endocytic arms of the synaptic vesicle cycle and advance our understanding of how synapses are maintained functionally and structurally. Finally, we show the involvement of CSPα-dependent synapse maintenance in disease states as Alzheimer's disease brains have a selective reduction in levels of CSPα.|
|Zhang YQ, Henderson MX, Colangelo CM, Ginsberg SD, Bruce C, Wu T, Chandra SS. (2012) Neuron. 2012 Apr 12;74(1):136-50. Identification of CSPα clients reveals a role in dynamin 1 regulation.
Acknowledgement: This work was supported by the YCCI Scholar Award (CTSA Grant UL1 RR024139; to S.S.C.), R01NS064963 (to S.S.C.), an Anonymous Foundation (to S.S.C.), W.M. Keck Foundation grant (to S.S.C.), NIDA Neuroproteomic Pilot Grant (5 P30 DA018343-07; to S.S.C.), Anderson Fellowship (to Y-Q.Z.), NSF Graduate Research Fellowship (to M.X.H.), and AG14449 (to S.D.G.).