Proteolysis of glutamate receptor-interacting protein by calpain in rat brain: implications for synaptic plasticity.
Activation of the calcium-dependent protease calpain has been proposed to be a key step in synaptic plasticity in the hippocampus. However, the exact pathway through which calpain mediates or modulates changes in synaptic function remains to be clarified. Here we report that glutamate receptor-interacting protein (GRIP) is a substrate of calpain, as calpain-mediated GRIP degradation was demonstrated using three different approaches: (i) purified calpain I digestion of synaptic membranes, (ii) calcium treatment of frozen-thawed brain sections, and (iii) NMDA-stimulated organotypic hippocampal slice cultures. More importantly, calpain activation resulted in the disruption of GRIP binding to the GluR2 subunit of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors. Because GRIP has been proposed to function as an AMPA receptor-targeting and synaptic-stabilizing protein, as well as a synaptic-organizing molecule, calpain-mediated degradation of GRIP and disruption of AMPA receptor anchoring are likely to play important roles in the structural and functional reorganization accompanying synaptic modifications in long-term potentiation and long-term depression.
Lu
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Neuroscience Program, University of Southern California, Los Angeles 90089-2520, USA.
Wyszynski
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Sheng
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Baudry
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D000818:Animals; D002154:Calpain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism; D013569:Synapses / Q000201:enzymology
D002352:Carrier Proteins; D018690:Excitatory Amino Acid Agonists; C491308:Grip1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; D016202:N-Methylaspartate; D002154:Calpain; C104722:glutamate receptor ionotropic, AMPA 2