Discovery of gene-gene interactions across multiple independent data sets of late onset Alzheimer disease from the Alzheimer Disease Genetics Consortium
NEUROBIOLOGY OF AGING
Authors: Hohman, Timothy J.; Bush, William S.; Jiang, Lan; Brown-Gentry, Kristin D.; Torstenson, Eric S.; Dudek, Scott M.; Mukherjee, Shubhabrata; Naj, Adam; Kunkle, Brian W.; Ritchie, Marylyn D.; Martin, Eden R.; Schellenberg, Gerard D.; Mayeux, Richard; Farrer, Lindsay A.; Pericak-Vance, Margaret A.; Haines, Jonathan L.; Thornton-Wells, Tricia A.
Abstract
Late-onset Alzheimer disease (AD) has a complex genetic etiology, involving locus heterogeneity, polygenic inheritance, and gene-gene interactions; however, the investigation of interactions in recent genome-wide association studies has been limited. We used a biological knowledge-driven approach to evaluate genegene interactions for consistency across 13 data sets from the Alzheimer Disease Genetics Consortium. Fifteen single nucleotide polymorphism (SNP)-SNP pairs within 3 gene-gene combinations were identified: SIRT1 x ABCB1, PSAP x PEBP4, and GRIN2B x ADRA1A. In addition, we extend a previously identified interaction from an endophenotype analysis between RYR3 x CACNA1C. Finally, post hoc gene expression analyses of the implicated SNPs further implicate SIRT1 and ABCB1, and implicate CDH23 which was most recently identified as an AD risk locus in an epigenetic analysis of AD. The observed interactions in this article highlight ways in which genotypic variation related to disease may depend on the genetic context in which it occurs. Further, our results highlight the utility of evaluating genetic interactions to explain additional variance in AD risk and identify novel molecular mechanisms of AD pathogenesis. (C) 2016 Elsevier Inc. All rights reserved.
GluN2B in corticostriatal circuits governs choice learning and choice shifting
NATURE NEUROSCIENCE
Authors: Brigman, Jonathan L.; Daut, Rachel A.; Wright, Tara; Gunduz-Cinar, Ozge; Graybeal, Carolyn; Davis, Margaret I.; Jiang, Zhihong; Saksida, Lisa M.; Jinde, Seiichiro; Pease, Matthew; Bussey, Timothy J.; Lovinger, David M.; Nakazawa, Kazu; Holmes, Andrew
Abstract
A choice that reliably produces a preferred outcome can be automated to liberate cognitive resources for other tasks. Should an outcome become less desirable, behavior must adapt in parallel or it becomes perseverative. Corticostriatal systems are known to mediate choice learning and flexibility, but the molecular mechanisms of these processes are not well understood. We integrated mouse behavioral, immunocytochemical, in vivo electrophysiological, genetic and pharmacological approaches to study choice. We found that the dorsal striatum (DS) was increasingly activated with choice learning, whereas reversal of learned choice engaged prefrontal regions. In vivo, DS neurons showed activity associated with reward anticipation and receipt that emerged with learning and relearning. Corticostriatal or striatal deletion of Grin2b (encoding the NMDA-type glutamate receptor subunit GluN2B) or DS-restricted GluN2B antagonism impaired choice learning, whereas cortical Grin2b deletion or OFC GluN2B antagonism impaired shifting. Our convergent data demonstrate how corticostriatal GluN2B circuits govern the ability to learn and shift choice behavior.