Genetic manipulation of key determinants of ion flow in glutamate receptor channels in the mouse.
Glutamate receptor channels are built around an ancient pore loop structure which defines the inner channel environment and which is connected to structures for channel gating. This pore loop, which corresponds to the M2 region of the receptor subunits, enters the lipid bilayer from the intracellular side in an alpha-helical configuration, then kinks to form a random coil and exits the lipid bilayer at the intracellular side. The narrow constriction of the channel is formed by amino acid residues that occupy a position shortly after the end of the alpha-helical part of M2. These residues determine ion selectivity and conductance properties of the glutamate-gated channel. The critical residues are asparagines for NMDA receptor subunits and glutamine or arginine for AMPA and kainate receptor subunits. Presence of arginine in the critical channel position of AMPA and kainate receptors is controlled by site-selective RNA editing. To study the importance of these critical channel residues in the mouse, we introduced codon changes in the endogenous genes for NMDA and AMPA receptor subunits. Our results show that changes in the critical channel position are not tolerated, but lead to early death. Therefore, the impact on adult synaptic function and plasticity by glutamate receptor channels with changed ion selectivity and conductance needs to be addressed by conditional expression of the mutant receptors.
Seeburg
P H
PH
Department of Molecular Neuroscience, Max-Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany. seeburg@mpimf-heidelberg.mpg.de
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Kuner
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Higuchi
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Sprengel
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D000241:Adenosine / Q000737:chemistry; D000243:Adenosine Deaminase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001923:Brain Chemistry; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D003062:Codon / Q000235:genetics; D018698:Glutamic Acid / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D017136:Ion Transport / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D021122:Protein Subunits; D017393:RNA Editing; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017470:Receptors, Glutamate / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
D000241:Adenosine; D000243:Adenosine Deaminase; D002118:Calcium; D015220:Calcium Channels; D003062:Codon; D018698:Glutamic Acid; D009419:Nerve Tissue Proteins; D021122:Protein Subunits; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D011993:Recombinant Fusion Proteins; C409466:NR1 NMDA receptor; C115953:glutamate receptor type B; C567955:ADARB1 protein, human