Homeostatic plasticity is crucial for maintaining neuronal output by counteracting unrestrained changes in synaptic strength. Chronic elevation of synaptic activity by bicuculline reduces the amplitude of miniature excitatory postsynaptic currents (mEPSCs), but the underlying mechanisms of this effect remain unclear. We found that activation of EphA4 resulted in a decrease in synaptic and surface GluR1 and attenuated mEPSC amplitude through a degradation pathway that requires the ubiquitin proteasome system (UPS). Elevated synaptic activity resulted in increased tyrosine phosphorylation of EphA4, which associated with the ubiquitin ligase anaphase-promoting complex (APC) and its activator Cdh1 in neurons in a ligand-dependent manner. APC(Cdh1) interacted with and targeted GluR1 for proteasomal degradation in vitro, whereas depletion of Cdh1 in neurons abolished the EphA4-dependent downregulation of GluR1. Knockdown of EphA4 or Cdh1 prevented the reduction in mEPSC amplitude in neurons that was a result of chronic elevated activity. Our results define a mechanism by which EphA4 regulates homeostatic plasticity through an APC(Cdh1)-dependent degradation pathway.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.