title: MeCP2 regulates the synaptic expression of a Dysbindin-BLOC-1 network component in mouse brain and human induced pluripotent stem cell-derived neurons.
abstract: Clinical, epidemiological, and genetic evidence suggest overlapping pathogenic mechanisms between autism spectrum disorder (ASD) and schizophrenia. We tested this hypothesis by asking if mutations in the ASD gene MECP2 which cause Rett syndrome affect the expression of genes encoding the schizophrenia risk factor dysbindin, a subunit of the biogenesis of lysosome-related organelles complex-1 (BLOC-1), and associated interacting proteins. We measured mRNA and protein levels of key components of a dysbindin interaction network by, quantitative real time PCR and quantitative immunohistochemistry in hippocampal samples of wild-type and Mecp2 mutant mice. In addition, we confirmed results by performing immunohistochemistry of normal human hippocampus and quantitative qRT-PCR of human inducible pluripotent stem cells (iPSCs)-derived human neurons from Rett syndrome patients. We defined the distribution of the BLOC-1 subunit pallidin in human and mouse hippocampus and contrasted this distribution with that of symptomatic Mecp2 mutant mice. Neurons from mutant mice and Rett syndrome patients displayed selectively reduced levels of pallidin transcript. Pallidin immunoreactivity decreased in the hippocampus of symptomatic Mecp2 mutant mice, a feature most prominent at asymmetric synapses as determined by immunoelectron microcopy. Pallidin immunoreactivity decreased concomitantly with reduced BDNF content in the hippocampus of Mecp2 mice. Similarly, BDNF content was reduced in the hippocampus of BLOC-1 deficient mice suggesting that genetic defects in BLOC-1 are upstream of the BDNF phenotype in Mecp2 deficient mice. Our results demonstrate that the ASD-related gene Mecp2 regulates the expression of components belonging to the dysbindin interactome and these molecular differences may contribute to synaptic phenotypes that characterize Mecp2 deficiencies and ASD.
authors.affiliation: Department of Biology, Agnes Scott College, Decatur, Georgia, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Larimore
authors.forename: Pearl V
authors.initials: PV
authors.lastname: Ryder
authors.forename: Kun-Yong
authors.initials: KY
authors.lastname: Kim
authors.forename: L Alex
authors.initials: LA
authors.lastname: Ambrose
authors.forename: Christopher
authors.initials: C
authors.lastname: Chapleau
authors.forename: Gaston
authors.initials: G
authors.lastname: Calfa
authors.forename: Christina
authors.initials: C
authors.lastname: Gross
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Bassell
authors.forename: Lucas
authors.initials: L
authors.lastname: Pozzo-Miller
authors.forename: Yoland
authors.initials: Y
authors.lastname: Smith
authors.forename: Konrad
authors.initials: K
authors.lastname: Talbot
authors.forename: In-Hyun
authors.initials: IH
authors.lastname: Park
authors.forename: Victor
authors.initials: V
authors.lastname: Faundez
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000166:cytology*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D051783:Methyl-CpG-Binding Protein 2 / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D060066:Protein Interaction Maps; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*
chemical_list: C400284:BLOC1S6 protein, human; D002352:Carrier Proteins; C432416:DTNBP1 protein, human; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins; D037102:Lectins; D051783:Methyl-CpG-Binding Protein 2; D012333:RNA, Messenger