mPins modulates PSD-95 and SAP102 trafficking and influences NMDA receptor surface expression

Nathalie Sans^1, 4, Philip Y. Wang¹, Quansheng Du², Ronald S. Petralia¹, Ya-Xian Wang¹, Sajan Nakka¹, Joe B. Blumer³, Ian G. Macara² & Robert J. Wenthold¹

¹  Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 50, Room 4146, 50 South Drive, Bethesda, MD 20892-8027, USA.

²  Center for Cell Signaling and Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.

³  Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, 1901 Perdido St., P7-1, New Orleans, LA 70112, USA.

⁴  Present address: Equipe AVENIR, IFR8, Institut National de la Sante et de la Recherche Medicale, Institut des Neurosciences F. Magendie, 33077 Bordeaux Cedex, France.

Appropriate trafficking and targeting of glutamate receptors (GluRs) to the postsynaptic density is crucial for synaptic function. We show that mPins (mammalian homologue of Drosophila melanogaster partner of inscuteable) interacts with SAP102 and PSD-95 (two PDZ proteins present in neurons), and functions in the formation of the NMDAR–MAGUK (N-methyl-D-aspartate receptor–membrane-associated guanylate kinase) complex. mPins enhances trafficking of SAP102 and NMDARs to the plasma membrane in neurons. Expression of dominant–negative constructs and short-interfering RNA (siRNA)-mediated knockdown of mPins decreases SAP102 in dendrites and modifies surface expression of NMDARs. mPins changes the number and morphology of dendritic spines and these effects depend on its Gi interaction domain, thus implicating G-protein signalling in the regulation of postsynaptic structure and trafficking of GluRs.

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