AMPA receptor stimulation increases alpha5beta1 integrin surface expression, adhesive function and signaling.
Integrin proteins are critical for stabilization of hippocampal long-term potentiation but the mechanisms by which integrin activities are involved in synaptic transmission are not known. The present study tested whether activation of alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionate (AMPA) class glutamate receptors increases surface expression of alpha5beta1 integrin implicated in synaptic potentiation. Surface protein biotinylation assays demonstrated that AMPA treatment of COS7 cells expressing GluR1 homomeric AMPA receptors increased membrane insertion and steady-state surface levels of alpha5 and beta1 subunits. Treated cells exhibited increased adhesion to fibronectin- and anti-alpha5-coated substrates and tyrosine kinase signaling elicited by fibronectin-substrate adhesion, as expected if new surface receptors are functional. Increased surface expression did not occur in calcium-free medium and was blocked by the protein kinase C inhibitor chelerythrine chloride and the exocytosis inhibitor brefeldin A. AMPA treatment similarly increased alpha5 and beta1 surface expression in dissociated neurons and cultured hippocampal slices. In both neuronal preparations AMPA-induced integrin trafficking was blocked by combined antagonism of NMDA receptor and L-type voltage-sensitive calcium channel activities but was not induced by NMDA treatment alone. These results provide the first evidence that glutamate receptor activation increases integrin surface expression and function, and suggest a novel mechanism by which synaptic activity can engage a volley of new integrin signaling in coordination with, and probably involved in, stabilization of synaptic potentiation.
Department of Anatomy and Neurobiology, University of California, Irvine, California 92697-4292, USA.
Ching-Yi
CY
Lin
Gary
G
Lynch
Christine M
CM
Gall
D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D019921:Biotinylation / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology; D020126:Brefeldin A / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005998:Glycine / Q000494:pharmacology; D066298:In Vitro Techniques; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D051419:Paxillin; D010617:Phenanthridines / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000502:physiology*; D013997:Time Factors; D014162:Transfection / Q000379:methods; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology*; D019061:src-Family Kinases / Q000378:metabolism
D000470:Alkaloids; D053119:Benzophenanthridines; D002121:Calcium Channel Blockers; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D039302:Integrin alphaVbeta3; D051419:Paxillin; D010617:Phenanthridines; D010750:Phosphoproteins; D011500:Protein Synthesis Inhibitors; C496063:Pxn protein, rat; D011810:Quinoxalines; D018091:Receptors, AMPA; D020126:Brefeldin A; C056723:FG 9041; C056639:2-amino-5-phosphopentanoic acid; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C016299:chelerythrine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D019061:src-Family Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D014633:Valine; D009543:Nifedipine; D005998:Glycine