Journal Article

α7 nicotinic acetylcholine receptor mRNA expression and binding in postmortem human brain are associated with genetic variation in neuregulin 1

Shiny V. Mathew, Amanda J. Law, Barbara K. Lipska, Martha I. Dávila-García, Eduardo D. Zamora, Shruti N. Mitkus, Radhakrishna Vakkalanka, Richard E. Straub, Daniel R. Weinberger, Joel E. Kleinman and Thomas M. Hyde

in Human Molecular Genetics

Volume 16, issue 23, pages 2921-2932
Published in print December 2007 | ISSN: 0964-6906
Published online September 2007 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddm253
α7 nicotinic acetylcholine receptor mRNA expression and binding in postmortem human brain are associated with genetic variation in neuregulin 1

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Studies in cell culture and in animals suggest that neuregulin 1 (NRG1), a probable schizophrenia susceptibility gene, regulates the expression of the α7 nicotinic acetylcholine receptors (nAChRs). We hypothesized that schizophrenia-associated allelic variations within the NRG1 gene, via their effects on NRG1 isoform expression, would be associated with alterations in nAChR α7 receptor levels. We examined the effects of four disease-associated single-nucleotide polymorphisms (SNPs) in the 5′ region of the NRG1 gene on nAChR α7 mRNA transcript expression in both the dorsolateral prefrontal cortex (DLPFC) and hippocampus of normal controls and patients with schizophrenia using quantitative real-time PCR. NRG1 risk alleles at SNPs SNP8NRG221132 and rs6994992 predicted significantly lower nAChR α7 mRNA expression in the DLPFC. Haplotypes containing the risk alleles at the above SNPs were also associated with lower expression of nAChR α7 in the DLPFC. The genotype effect for rs6994992 and the haplotype effect were more pronounced within the schizophrenic patient group. To determine whether receptor levels follow that of mRNA expression, we performed receptor binding and autoradiography using [125I] α-bungarotoxin in the DLPFC. Consistent with the mRNA findings, we found a decrease in binding in risk allele carriers of SNP8NRG221132 as compared with heterozygous individuals. Together, these results suggest that the molecular mechanism of the association between NRG1 risk alleles and schizophrenia may include down-regulation of nAChR α7 expression.

Journal Article.  7215 words.  Illustrated.

Subjects: Genetics and Genomics

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