?3 integrin interacts directly with GluA2 AMPA receptor subunit and regulates AMPA receptor expression in hippocampal neurons.

ABSTRACT: The integrins are transmembrane receptors for ECM proteins, and they regulate various cellular functions in the central nervous system. In hippocampal neurons, the ?3 integrin subtype is required for homeostatic synaptic scaling of AMPA receptors (AMPARs) induced by chronic activity deprivation. The surface level of ?3 integrin in postsynaptic neurons directly correlates with synaptic strength and the abundance of synaptic GluA2 AMPAR subunit. Although these observations suggest a functional link between ?3 integrin and AMPAR, little is known about the mechanistic basis for the connection. Here we investigate the nature of ?3 integrin and AMPAR interaction underlying the ?3 integrin-dependent control of synaptic AMPAR expression and thus synaptic strength. We show that ?3 integrin and GluA2 subunit form a complex in mouse brain that involves the direct binding between their cytoplasmic domains. In contrast, ?3 integrin associates with GluA1 AMPAR subunit only weakly, and, in a heterologous expression system, the interaction requires the coexpression of GluA2. Surprisingly, in hippocampal pyramidal neurons, expressing ?3 integrin mutants with either increased or decreased affinity for extracellular ligands has no differential effects in elevating excitatory synaptic currents and surface GluA2 levels compared with WT ?3 integrin. Our findings identify an integrin family member, ?3, as a direct interactor of an AMPAR subunit and provide molecular insights into how this cell-adhesion protein regulates the composition of cell-surface AMPARs.

SUBMITTER: Pozo K 

PROVIDER: S-EPMC3268285 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature