PT  - JOURNAL ARTICLE
AU  - Jung-Hwa Tao-Cheng
AU  - Rita Azzam
AU  - Virginia Crocker
AU  - Christine A. Winters
AU  - Tom Reese
TI  - Depolarization of Hippocampal Neurons Induces Formation of Nonsynaptic NMDA Receptor Islands Resembling Nascent Postsynaptic Densities
AID  - 10.1523/ENEURO.0066-15.2015
DP  - 2015 Nov 01
TA  - eneuro
PG  - ENEURO.0066-15.2015
VI  - 2
IP  - 6
4099  - http://www.eneuro.org/content/2/6/ENEURO.0066-15.2015.short
4100  - http://www.eneuro.org/content/2/6/ENEURO.0066-15.2015.full
SO  - eneuro2015 Nov 01; 2
AB  - Depolarization of neurons in 3-week-old rat hippocampal cultures promotes a rapid increase in the density of surface NMDA receptors (NRs), accompanied by transient formation of nonsynaptic NMDA receptor clusters or NR islands. Islands exhibit cytoplasmic dense material resembling that at postsynaptic densities (PSDs), and contain typical PSD components, including MAGUKS (membrane-associated guanylate kinases), GKAP, Shank, Homer, and CaMKII detected by pre-embedding immunogold electron microscopy. In contrast to mature PSDs, islands contain more NMDA than AMPA receptors, and more SAP102 than PSD-95, features that are shared with nascent PSDs in developing synapses. Islands do not appear to be exocytosed or endocytosed directly as preformed packages because neurons lacked intracellular vacuoles containing island-like structures. Islands form and disassemble upon depolarization of neurons on a time scale of 2-3 min, perhaps representing an initial stage in synaptogenesis.