Project Details

Description

DESCRIPTION (provided by applicant): Autism spectrum disorder (ASD) is a common and debilitating neurodevelopmental disorder. Although there is strong evidence for a genetic contribution to ASD, the isolation of specific causative genetic defects has been difficult. Our previous research has focused on the homeobox transcription factor ENGRAILED 2 (EN2). We have demonstrated consistent association for two intronic EN2 SNPs, rs1861972 and rs1861973, in three separate datasets. These findings determined that EN2 is a likely ASD susceptibility gene. LD mapping and re-sequencing identified the associated A-C rs1861972-rs1816973 haplotype as a candidate disease allele. Functional studies have now demonstrated that the EN2 intron acts a transcriptional repressor and that the A-C haplotype results in a weaker repressor compared to the non-associated G-T haplotype. EMSAs have determined that DNA binding proteins specifically interact with the associated alleles for both SNPs, providing a mechanism for the observed functional difference. These studies have identified the A-C haplotype as the first common risk factor for autism. The goal of this proposal is to generate a mouse model for the EN2 risk allele by using recombinase- mediated genomic replacement (RMGR). RMGR is preferred over standard targeting approaches because large segments of the mouse genome (>100kb) can be replaced with the syntenic human region. This reduces concerns about the proper regulation of the human gene. Our plan is to use RMGR to replace ~72kb of the mouse En2 locus with the syntenic human region and to generate knock-in lines for both the associated A-C and the non-associated G-T haplotypes. An IRES:red fluorescent protein (DsRed-E5/pTIMER) will also be used to modify the EN2 locus so that subtle effects of the risk allele on levels and spatial/temporal expression can be identified. The knock-ins will then be examined to determine the developmental cell types and ages in which the EN2 risk allele is functional. Studies with the En2 knock-out have uncovered anatomical, developmental and neurochemical phenotypes relevant to ASD. The same analysis will be repeated for the knock-ins as a first step in determining the cellular pathways affected by the risk allele. This information will be critical in the development of better diagnoses, treatments and preventions for ASD.
StatusFinished
Effective start/end date5/5/084/30/12

Funding

  • National Institutes of Health: $152,667.00
  • National Institutes of Health: $152,764.00
  • National Institutes of Health: $227,135.00

ASJC

  • Medicine(all)

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