Synapse-associated protein-97 isoform-specific regulation of surface AMPA receptors and synaptic function in cultured neurons.
Members of the synapse-associated protein-97 (SAP97) family of scaffold proteins have been implicated as central organizers of synaptic junctions to build macromolecular signaling complexes around specific postsynaptic neurotransmitter receptors. In this regard, SAP97 has been suggested to regulate the synaptic localization of glutamate receptor type 1 subunits of the AMPA-type glutamate receptors. To test this hypothesis directly, we assessed the effects of SAP97 overexpression on surface expression of synaptic AMPA receptors. We find that recombinant SAP97 not only becomes concentrated at synaptic junctions but also leads to an increase in synaptic AMPA receptors, spine enlargement, and an increase in miniature EPSC (mEPSC) frequency, indicating that SAP97 has both postsynaptic and presynaptic effects on synaptic transmission. Synaptic targeting of SAP97, increased surface AMPA receptors, and increased mEPSC frequency are dependent on the presence of specific alternatively spliced sequences in SAP97 that encode a protein 4.1 binding site. These results suggest that SAP97 can affect the synaptic recruitment of AMPA receptors and spine morphology and that these effects may be regulated by alternative splicing.
Rumbaugh
Gavin
G
Howard Hughes Medical Institute and Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Sia
Gek-Ming
GM
Garner
Craig C
CC
Huganir
Richard L
RL
D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D022081:Cell Surface Extensions / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000166:cytology; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009479:Neuropeptides; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; C501119:Dlg1 protein, rat; D008164:Luminescent Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D020033:Protein Isoforms; D018091:Receptors, AMPA; D011993:Recombinant Fusion Proteins; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D049452:Green Fluorescent Proteins