Mouse mutants that perturb cortical patterning have provided considerable insight into the development of the mammalian brain. We have previously undertaken a project to generate models of human congenital defects by screening ENU-mutagenized mice for recessive mutations affecting late embryonic development. The screen incorporated a genetic mapping component, with the intent to facilitate the positional cloning and functional characterization of the mutant genes. The strategy has worked well, and we have generated many mice with phenotypes similar to human malformation syndromes and birth defects. In this proposal we aim to target cortical development, with the goal of identifying and cloning additional mutants that will be useful for understanding how the mammalian brain is patterned. Specifically, we plan to screen for mice that have abnormalities of brain morpholology and histology. We will also screen for mutations that perturb patterning of reporter genes that mark specific anatomical structures, A third strategy is to screen for mutations that have a genetic interaction with known cortical patterning genes such as Lis1. We have developed efficient strategies for genetic mapping and positional cloning, and we are currently working on rapid methods of mutation validation using RNAi. Finally, for a subset of mutations that have relatively specific effects on cortical development, we plan to pursue in-depth analysis, including a collaborative effort with investigators at the Allen Institute for Brain Science utilizing high-throughput technologies for in situ expression analysis. Depending upon the nature of the mutated gene, we will pursue functional studies as appropriate.

Public Health Relevance

. We propose to treat mice with the chemical ethyl-nitrosourea (ENU), which causes mutations in DNA. We will examine the progeny of treated mice to assess whether they have disorders of brain development. We are particularly interested in those that have relatively subtle effects;that is, which appear to specifically affect the formation of the brain, but not other organs. Once we have generated these mutants, we will use state-of-the-art methods of genome analysis to identify the mutated gene. With these in hand, we can begin to evaluate what developmental pathways are affected in these abnormal mice. Understanding the formation of the brain will likely help us to understand the roots of the many brain diseases affecting one in five Americans today (www.ninds.nih.gov). These diseases include developmental disorders (including autism), degenerative diseases of adult life, metabolic diseases, and brain tumors. Defects in neuronal migration within the forebrain lead to mental retardation, epilepsy and severe learning disabilities. The forebrain is also primarily affected in many other diseases such as Parkinson's and Huntington's diseases and schizophrenia. Significant efforts, both public and private, are currently underway to begin to identify more of the genes expressed in the brain at various stages as well as their expression patterns. This information, combined with the mutational analysis we plan, will help uncover the basic steps required for normal brain development.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH081187-05
Application #
8290502
Study Section
Special Emphasis Panel (ZRG1-MDCN-K (90))
Program Officer
Beckel-Mitchener, Andrea C
Project Start
2008-07-01
Project End
2012-11-30
Budget Start
2012-07-01
Budget End
2012-11-30
Support Year
5
Fiscal Year
2012
Total Cost
$287,013
Indirect Cost
$65,397
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
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Ha, Seungshin; Lindsay, Anna M; Timms, Andrew E et al. (2016) Mutations in Dnaaf1 and Lrrc48 Cause Hydrocephalus, Laterality Defects, and Sinusitis in Mice. G3 (Bethesda) 6:2479-87
Menke, Chelsea; Cionni, Megan; Siggers, Trevor et al. (2015) Grhl2 is required in nonneural tissues for neural progenitor survival and forebrain development. Genesis :
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Stottmann, Rolf; Beier, David (2014) ENU Mutagenesis in the Mouse. Curr Protoc Hum Genet 82:15.4.1-10
Favero, Carlita B; Henshaw, Rasha N; Grimsley-Myers, Cynthia M et al. (2013) Mutation of the BiP/GRP78 gene causes axon outgrowth and fasciculation defects in the thalamocortical connections of the mammalian forebrain. J Comp Neurol 521:677-96
Stottmann, R W; Donlin, M; Hafner, A et al. (2013) A mutation in Tubb2b, a human polymicrogyria gene, leads to lethality and abnormal cortical development in the mouse. Hum Mol Genet 22:4053-63
Leshchiner, Ignaty; Alexa, Kristen; Kelsey, Peter et al. (2012) Mutation mapping and identification by whole-genome sequencing. Genome Res 22:1541-8

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