Camkii-mediated phosphorylation regulates distributions of Syngap-α1 and -α2 at the postsynaptic density

• Published in: PloS one 2013-08, Vol.8 (8), p.e71795-e71795
• Main Authors: Yang, Yijung, Tao-Cheng, Jung-Hwa, Bayer, K Ulrich, Reese, Thomas S, Dosemeci, Ayse
• Format: Article
• Language: English
• Subjects: Activation; Animals; Antibodies; Biology; Brain; Ca2+/calmodulin-dependent protein kinase II; Calcium - metabolism; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - metabolism; Calmodulin - metabolism; Cell culture; Density; Electron microscopy; Enzyme Activation; Glutamatergic transmission; GTPase-Activating Proteins - metabolism; Hippocampus; Immunoblotting; Information storage; Isoforms; Kinases; Laboratories; Microscopy; N-Methyl-D-aspartic acid; N-Methylaspartate - metabolism; N-Methylaspartate - pharmacology; Nervous system; Neurobiology; Neurological disorders; Neurons; Neurosciences; Peptides; Phosphorylation; Polyclonal antibodies; Post-Synaptic Density - metabolism; Postsynaptic density; Protein Transport - drug effects; Proteins; Rats; Receptors; Rodents; Synapses; Synaptic Membranes - metabolism; Synaptic strength; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0071795

SynGAP, a protein abundant at the postsynaptic density (PSD) of glutamatergic neurons, is known to modulate synaptic strength by regulating the incorporation of AMPA receptors at the synapse. Two isoforms of SynGAP, α1 and α2, which differ in their C-termini, have opposing effects on synaptic strength. In the present study, antibodies specific for SynGAP-α1 and SynGAP-α2 are used to compare the distribution patterns of the two isoforms at the postsynaptic density (PSD) under basal and excitatory conditions. Western immunoblotting shows enrichment of both isoforms in PSD fractions isolated from adult rat brain. Immunogold electron microscopy of rat hippocampal neuronal cultures shows similar distribution of both isoforms at the PSD, with a high density of immunolabel within the PSD core under basal conditions. Application of NMDA promotes movement of SynGAP-α1 as well as SynGAP-α2 out of the PSD core. In isolated PSDs both isoforms of SynGAP can be phosphorylated upon activation of the endogenous CaMKII. Application of tatCN21, a cell-penetrating inhibitor of CaMKII, to hippocampal neuronal cultures blocks NMDA-induced redistribution of SynGAP-α1 and SynGAP-α2. Thus CaMKII activation promotes the removal of two distinct C-terminal SynGAP variants from the PSD.