Candidate autism gene screen identifies critical role for cell-adhesion molecule CASPR2 in dendritic arborization and spine development

Department of Molecular and Cellular Physiology, Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 10/2012; 109(44). DOI: 10.1073/pnas.1216398109
Source: PubMed


Mutations in the contactin-associated protein 2 (CNTNAP2) gene encoding CASPR2, a neurexin-related cell-adhesion molecule, predispose to autism, but the function of CASPR2 in neural circuit assembly remains largely unknown. In a knockdown survey of autism candidate genes, we found that CASPR2 is required for normal development of neural networks. RNAi-mediated knockdown of CASPR2 produced a cell-autonomous decrease in dendritic arborization and spine development in pyramidal neurons, leading to a global decline in excitatory and inhibitory synapse numbers and a decrease in synaptic transmission without a detectable change in the properties of these synapses. Our data suggest that in addition to the previously described role of CASPR2 in mature neurons, where CASPR2 organizes nodal microdomains of myelinated axons, CASPR2 performs an earlier organizational function in developing neurons that is essential for neural circuit assembly and operates coincident with the time of autism spectrum disorder (ASD) pathogenesis.

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Available from: Jason Aoto, May 05, 2015
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    • "Caspr2-deficient mice show a defect in the migration of cortical neurons and a reduction in the number of GABAergic interneurons which are associated with an epileptic phenotype and autism-related behaviors (Penagarikano et al., 2011). RNAimediated knockdown of Caspr2 affects synaptic organization and function in culture (Anderson et al., 2012). Mutations of the Caspr2 gene (cntnap2) have been unambiguously associated with neuropsychiatric disorders, such as developmental language impairment and autistic spectrum disorders (Strauss et al., 2006; Bakkaloglu et al., 2008; Penagarikano and Geschwind, 2012; Rodenas-Cuadrado et al., 2013). "
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    ABSTRACT: Contactin-associated protein-like 2 (Caspr2), also known as CNTNAP2, is a cell adhesion molecule that clusters voltage-gated potassium channels (Kv1.1/1.2) at the juxtaparanodes of myelinated axons and may regulate axonal excitability. As a component of the Kv1 complex, Caspr2 has been identified as a target in neuromyotonia and Morvan syndrome, but also in some cases of autoimmune limbic encephalitis (LE). How anti-Caspr2 autoimmunity is linked with the central neurological symptoms is still elusive. In the present study, using anti-Caspr2 antibodies from seven patients affected by pure LE, we determined that IgGs in the cerebrospinal fluid of four out seven patients were selectively directed against the N-terminal Discoïdin and LamininG1 modules of Caspr2. Using live immunolabeling of cultured hippocampal neurons, we determined that serum IgGs in all patients strongly targeted inhibitory interneurons. Caspr2 was highly detected on GAD65-positive axons that are surrounding the cell bodies and at the VGAT-positive inhibitory presynaptic contacts. Functional assays indicated that LE autoantibodies may induce alteration of Gephyrin clusters at inhibitory synaptic contacts. Next, we generated a Caspr2-Fc chimera to reveal Caspr2 receptors on hippocampal neurons localized at the somato-dendritic compartment and post-synapse. Caspr2-Fc binding was strongly increased on TAG-1-transfected neurons and conversely, Caspr2-Fc did not bind hippocampal neurons from TAG-1-deficient mice. Our data indicate that Caspr2 may participate as a cell recognition molecule in the dynamics of inhibitory networks. This study provides new insight into the potential pathogenic effect of anti-Caspr2 autoantibodies in central hyperexcitability that may be related with perturbation of inhibitory interneuron activity.
    Frontiers in Cellular Neuroscience 07/2015; 9:265. DOI:10.3389/fncel.2015.00265 · 4.29 Impact Factor
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    • "Purple vertical bars indicate the position of the cell membrane. Poot Mol Syndromol 2015;6:7–22 DOI: 10.1159/000371594 10 in excitatory and inhibitory synapse numbers and a decrease in synaptic transmission [Anderson et al., 2012]. "
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    ABSTRACT: Based on genomic rearrangements and copy number variations the contactin associated protein 2 gene (CNTNAP2) has been implicated in neurodevelopmental disorders such as Gilles de la Tourette syndrome (GTS) , intellectual disability, obsessive compulsive disorder, cortical dysplasia-focal epilepsy syndrome, autism, schizophrenia, Pitt Hopkins syndrome, and attention span / hyperactivity disorder (ADHD). To explain the phenotypic pleiotropy of CNTNAP2 alterations several hypotheses have been put forward. Those include gene disruption, loss of a gene copy by a heterozygous deletion, altered regulation of gene expression due to loss of transcription factor binding and DNA methylation sites, and mutations in the amino acid sequence of the encoded protein, which may provoke altered interactions of the CNTNAP2-encoded protein, Caspr2, with other proteins. Also exome sequencing, which covers less than 0.2% of the CNTNAP2 genomic DNA, has revealed numerous single nucleotide variants in healthy individuals and in patients with neurodevelopmental disorders. In some of these disorders disruption of CNTNAP2 may be interpreted as a susceptibility factor rather than a directly causative mutation. In addition to being associated with impaired development of language, CNTNAP2 may turn out to be a central node in the molecular networks controlling neurodevelopment. This review discusses the impact of CNTNAP2 mutations on its functioning at multiple levels of the combinatorial genetic networks that govern brain development. In addition, recommendations for genomic testing in the context of clinical genetic management of patients with neurodevelopmental disorders and their families are put forward.
    Molecular syndromology 01/2015; 6. DOI:10.1159/000371594
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    • "MYO1G encodes a plasma membrane-associated class I myosin that is expressed abundantly in hematopoietic cells; it regulates cell elasticity and migration (Olety et al. 2010; Patino-Lopez et al. 2010). CNTNAP2 encodes a member of the neurexin family of cell-adhesion molecules that plays a critical role in brain development (Anderson et al. 2012), and has been implicated in a number of neurodevelopmental disorders, including autism (Anney et al. 2012). One of the main functions of DNAm is the regulation of gene expression. "
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    ABSTRACT: Background: Prenatal exposure to maternal cigarette smoking (prenatal smoke exposure) had been associated with altered DNA methylation (DNAm) at birth. Objective: We examined whether such alterations are present from birth through adolescence. Methods: We used the Infinium HumanMethylation450K BeadChip to search across 473,395 CpGs for differential DNAm associated with prenatal smoke exposure during adolescence in a discovery cohort (n = 132) and at birth, during childhood, and during adolescence in a replication cohort (n = 447). Results: In the discovery cohort, we found five CpGs in MYO1G (top-ranking CpG: cg12803068, p = 3.3 × 10–11) and CNTNAP2 (cg25949550, p = 4.0 × 10–9) to be differentially methylated between exposed and nonexposed individuals during adolescence. The CpGs in MYO1G and CNTNAP2 were associated, respectively, with higher and lower DNAm in exposed versus nonexposed adolescents. The same CpGs were differentially methylated at birth, during childhood, and during adolescence in the replication cohort. In both cohorts and at all developmental time points, the differential DNAm was in the same direction and of a similar magnitude, and was not altered appreciably by adjustment for current smoking by the participants or their parents. In addition, four of the five EWAS (epigenome-wide association study)–significant CpGs in the adolescent discovery cohort were also among the top sites of differential methylation in a previous birth cohort, and differential methylation of CpGs in CYP1A1, AHRR, and GFI1 observed in that study was also evident in our discovery cohort. Conclusions: Our findings suggest that modifications of DNAm associated with prenatal maternal smoking may persist in exposed offspring for many years—at least until adolescence. Citation: Lee KW, Richmond R, Hu P, French L, Shin J, Bourdon C, Reischl E, Waldenberger M, Zeilinger S, Gaunt T, McArdle W, Ring S, Woodward G, Bouchard L, Gaudet D, Davey Smith G, Relton C, Paus T, Pausova Z. 2015. Prenatal exposure to maternal cigarette smoking and DNA methylation: epigenome-wide association in a discovery sample of adolescents and replication in an independent cohort at birth through 17 years of age. Environ Health Perspect 123:193–199;
    Environmental Health Perspectives 10/2014; 123(2). DOI:10.1289/ehp.1408614 · 7.98 Impact Factor
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