title: The β3 subunit of the nicotinic acetylcholine receptor: Modulation of gene expression and nicotine consumption.
abstract: Genetic factors explain approximately half of the variance in smoking behaviors, but the molecular mechanism by which genetic variation influences behavior is poorly understood. SNPs in the putative promoter region of CHRNB3, the gene that encodes the β3 subunit of the nicotinic acetylcholine receptor (nAChR), have been repeatedly associated with nicotine behaviors. In this work we sought to identify putative function of three SNPs in the promoter region of CHRNB3 on in vitro gene expression. Additionally, we used β3 null mutant mice as a model of reduced gene expression to assess the effects on nicotine behaviors. The effect of rs13277254, rs6474413, and rs4950 on reporter gene expression was examined using a luciferase reporter assay. A major and minor parent haplotype served as the background on which alleles at the three SNPs were flipped onto different backgrounds (e.g. minor allele on major haplotype background). Constructs were tested in three human cell lines: BE(2)-C, SH-SY5Y and HEK293T. In all cell types the major haplotype led to greater reporter gene expression compared to the minor haplotype, and results indicate that this effect is driven by rs6474413. Moreover, mice lacking the β3 subunit showed reduced voluntary nicotine consumption compared that of wildtype animals. These data provide evidence that the protective genetic variant at rs6474413 identified in human genetic studies reduces gene expression and that decreased β3 gene expression in mice reduces nicotine intake. This work contributes to our understanding of the molecular mechanisms that contribute to the human genetic associations of tobacco behaviors.
authors: Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA 16802, USA. Electronic address: hmk123@psu.edu.
authors: Helen M
authors: HM
authors: Kamens
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA.
authors: Jill
authors: J
authors: Miyamoto
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA.
authors: Matthew S
authors: MS
authors: Powers
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA.
authors: Kasey
authors: K
authors: Ro
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA.
authors: Marissa
authors: M
authors: Soto
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA.
authors: Ryan
authors: R
authors: Cox
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA; Department of Integrative Physiology, University of Colorado, Boulder, CO 80303, USA.
authors: Jerry A
authors: JA
authors: Stitzel
authors: Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80303, USA; Department of Integrative Physiology, University of Colorado, Boulder, CO 80303, USA.
authors: Marissa A
authors: MA
authors: Ehringer
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D057809:HEK293 Cells; D006239:Haplotypes; D006801:Humans; D008297:Male; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000008:administration & dosage*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011978:Receptors, Nicotinic / Q000235:genetics* / Q000378:metabolism*
chemical_list: C539371:CHRNB3 protein, human; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; C568453:nicotinic receptor beta3, mouse; D009538:Nicotine
keywords: Consumption; Gene expression; Luciferase; Nicotine; Nicotinic acetylcholine receptors