Abstract
The activity-regulated cytoskeleton-associated (Arc) protein controls synaptic strength by facilitating AMPA receptor (AMPAR) endocytosis. Here we demonstrate that Arc targets AMPAR to be internalized through a direct interaction with the clathrin-adaptor protein 2 (AP-2). We show that Arc overexpression in dissociated hippocampal neurons obtained from C57BL/6 mouse reduces the density of AMPAR GluA1 subunits at the cell surface and reduces the amplitude and rectification of AMPAR-mediated miniature-EPSCs (mEPSCs). Mutations of Arc, that prevent the AP-2 interaction reduce Arc-mediated endocytosis of GluA1 and abolish the reduction in AMPAR-mediated mEPSC amplitude and rectification. Depletion of the AP-2 subunit µ2 blocks the Arc-mediated reduction in mEPSC amplitude, an effect that is restored by reintroducing µ2. The Arc–AP-2 interaction plays an important role in homeostatic synaptic scaling as the Arc-dependent decrease in mEPSC amplitude, induced by a chronic increase in neuronal activity, is inhibited by AP-2 depletion. These data provide a mechanism to explain how activity-dependent expression of Arc decisively controls the fate of AMPAR at the cell surface and modulates synaptic strength, via the direct interaction with the endocytic clathrin adaptor AP-2.
- : adaptor protein 2
- AMPAR endocytosis
- clathrin-mediated endocytosis
- hippocampus
- neuronal excitability
- synaptic transmission
Footnotes
↵1 The authors report no conflict of interest.
↵3 This work was supported by the BBSRC_FAPPA BB/J02127X/1 and BBSRC-BB/H018344/1 to S.A.L.C. and by the FAPESP_RCUK_FAPPA 2012/50147-5 and FAPESP_Young Investigator’s Grant 2009/50650-6 to L.L.D. S.C.W. was a PhD student supported be the BBSRC/GSK PhD-CASE Studentship, L.P.d.A. is a postdoctoral fellow supported by FAPESP, and Y.C.J. was supported by a FAPESP scientific initiation scholarship. We thank Drs Jason D. Shepherd and Dawn R. Collins for helpful comments on the paper, Dr Rodrigo O de Castro for helpful advice on the GST-pull down experiments, Dr Juan Bonifacino for providing the AP-2 core construct and Jeremy M. Henley for providing the myc-tagged GluA1 and GluA2 constructs.
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