Wang, Ying and Xiao, Cheng and Indersmitten, Tim and Freedman, Robert and Leonard, Sherry and Lester, Henry A. (2014) The duplicated α7 subunits assemble and form functional nicotinic receptors with the full-length α7. Journal of Biological Chemistry . ISSN 0021-9258. http://resolver.caltech.edu/CaltechAUTHORS:20140729-082327052
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The α7 nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. A partial duplication of CHRNA7 (CHRFAM7A) is found in humans on 15q13-14. Exon 6 of CHRFAM7A harbors a 2 base pair deletion polymorphism, CHRFAM7AΔ2bp, which is also associated with schizophrenia. To understand the effects of the duplicated subunits on α7 receptors, we fused α7, dupα7, and dupΔα7 subunits with various fluorescent proteins. The duplicated subunits co-localized with full-length α7 subunits in mouse neuroblastoma cells (Neuro2a) as well as rat hippocampal neurons. We investigated the interaction between the duplicated subunits and full-length α7 by measuring Foerster resonance energy transfer (FRET) using donor recovery after photobleaching (DRAP) and fluorescence lifetime imaging microscopy (FLIM). The results revealed that the duplicated proteins co-assemble with α7. In electrophysiological studies, leucine at the 9' position in the M2 membrane-spanning segment was replaced with Cys in dupα7 or dupΔα7, and constructs were cotransfected with full-length α7 in Neuro2a cells. Exposure to ethylammonium methanethiosulfonate (MTSEA) inhibited acetylcholine (ACh)-induced currents, showing that the assembled functional nAChRs included the duplicated subunit. Incorporation of dupα7 and dup∆α7 subunits modestly changes the sensitivity of receptors to choline and varenicline. Thus, the duplicated proteins are assembled and transported to the cell membrane together with full-length α7 subunits, and alter the function of the nAChRs. The characterization of dupα7 and dupΔα7 as well as their influence on α7 nAChRs may help explain the pathophysiology of schizophrenia and may suggest therapeutic strategies.
|Additional Information:||© 2014 The American Society for Biochemistry and Molecular Biology. Published on July 23, 2014 as Manuscript M114.582858. Thanks to Sheri McKinney for providing neuron cultures. We also thank Drs. Christopher I. Richards and Bruce N. Cohen for helpful discussions. This work was supported by the National Institutes of Health (MH088550).|
|Subject Keywords:||electrophysiology; fluorescence recovery after photobleaching (FRAP); fluorescence resonance energy transfer (FRET); genomics; ion channel; nicotinic acetylcholine receptors (nAChR); patch clamp; schizophrenia; choline; ligand-gated channel|
|Official Citation:||Wang, Y., Xiao, C., Indersmitten, T., Freedman, R., Leonard, S., & Lester, H. A. (2014). The duplicated α7 subunits assemble and form functional nicotinic receptors with the full-length α7. Journal of Biological Chemistry. doi: 10.1074/jbc.M114.582858|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||29 Jul 2014 23:05|
|Last Modified:||30 Jul 2014 01:35|
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