title: Brain-specific regulator of G-protein signaling 9-2 selectively interacts with alpha-actinin-2 to regulate calcium-dependent inactivation of NMDA receptors.
abstract: Regulator of G-protein signaling 9-1 (RGS9-1) and RGS9-2 are highly related RGS proteins with distinctive C termini arising from alternative splicing of RGS9 gene transcripts. RGS9-1 is expressed in photoreceptors where it functions as a regulator of transducin. In contrast, RGS9-2 is abundantly expressed in the brain, especially in basal ganglia, where its specific function remains poorly understood. To gain insight into the function of RGS9-2, we screened a human cDNA library for potential interacting proteins. This screen identified a strong interaction between RGS9-2 and alpha-actinin-2, suggesting a possible functional relationship between these proteins. Consistent with this idea, RGS9-2 and alpha-actinin-2 coimmunoprecipitated after coexpression in human embryonic kidney 293 (HEK-293) cells. Furthermore, endogenous RGS9-2 and alpha-actinin-2 could also be coimmunoprecipitated from extracts of rat striatum, an area highly enriched in both these proteins. These results supported the idea that RGS9-2 and alpha-actinin-2 could act in concert in central neurons. Like alpha-actinin-2, RGS9-2 coimmunoprecipitated NMDA receptors from striatal extracts, suggesting an interaction between RGS9-2, alpha-actinin-2, and NMDA receptors. Previous studies have shown that alpha-actinin mediates calcium-dependent inactivation of NMDA receptors. In HEK-293 cells expressing NMDA receptors, expression of RGS9-2 significantly modulated this form of NMDA receptor inactivation. Furthermore, this modulation showed remarkable preference for NMDA receptor inactivation mediated by alpha-actinin-2. Using a series of deletion constructs, we localized this effect to the RGS domain of the protein. These results identify an unexpected functional interaction between RGS9-2 and alpha-actinin-2 and suggest a potential novel role for RGS9-2 in the regulation of NMDA receptor function.
authors.affiliation: Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bouhamdan
authors.forename: Hai-Dun
authors.initials: HD
authors.lastname: Yan
authors.forename: Xiu-Hua
authors.initials: XH
authors.lastname: Yan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bannon
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Andrade
mesh_terms: D000185:Actinin / Q000502:physiology*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008565:Membrane Proteins / Q000502:physiology*; D016202:N-Methylaspartate / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D016548:Prosencephalon / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D014162:Transfection / Q000379:methods; D020798:Two-Hybrid System Techniques
chemical_list: C401401:ACTN2 protein, human; D048868:Adaptor Proteins, Signal Transducing; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D008565:Membrane Proteins; C409466:NR1 NMDA receptor; D015221:Potassium Channels; C464657:RGS9BP protein, human; D016194:Receptors, N-Methyl-D-Aspartate; D000185:Actinin; D016202:N-Methylaspartate; D011188:Potassium; D002118:Calcium