The Molecular Genetics of Early Neurogenesis


Principal Investigator: Ethan Bier
Abstract: DESCRIPTION (provided by applicant): The ability to direct gene expression to specific cell types in space and time is an important goal for regenerative medicine. For example, to treat dorsal spinal chord injuries one may wish to direct differentiating stem cells to assume sensory or neural crest fates under the control of local inductive signals such as Bone morphogenetic proteins (BMPs). BMPs play a highly conserved role during neural induction to establish the dorsal-ventral (DV) axis and to distinguish epidermal from central nervous system cell fates. Subsequently, BMPs determine cell fates within dorsal regions of the spinal chord, where they act via highly conserved effector genes. In Drosophila and vertebrates alike, dorsal cells of the CNS form along the border of the BMP producing epidermis and express the Msx1 transcription factor (msh in flies), while other transcription factors Pax6 and Gsh (ind in flies) and Nkx2.2 (vn in flies) are expressed respectively in lateral and ventral domains of the CNS. These conserved "neural identity" genes determine the fates of cells in which they are expressed, but may be regulated differently by BMPs in flies and vertebrates. Thus, in flies, genetic data indicate that BMPs act as they do during neural induction to repress expression ind and msh in a dose-dependent fashion. In vertebrates, however, BMPs have been proposed to positively regulate genes such as Msx1. Analysis of BMP-dependent cis-regulation of neural identity genes has broad evolutionary implications and should aid in the development of designer cis-regulator modules (CRMs) to target neuronal differentiation to specific regions of the spinal chord. In the current grant, we propose to carry out a comparative mechanistic study of CRMs controlling BMP-responsive expression of neural identity genes in Drosophila and vertebrates. In Aim 1, we will examine the cis-regulatory basis for BMP-mediated repression of msh expression as compared to that of ind, which is more strongly repressed by BMPs. Using cutting edge imaging and quantitative methods we have developed for precisely measuring gene expression levels at single-cell resolution, we will also examine the mechanism by which the ind and msh expression domains resolve into mutually exclusive adjacent territories. In Aim 2, we will identify and analyze vertebrate CRMs driving differential expression of neural identity genes in the neural plate/tube of zebrafish embryos. In collaboration with Shannon Fisher's group (Univ. Penn), we have recently identified zebrafish msxB and mouse Msx1 CRMs that accurately drive reporter gene expression in the dorsal CNS. We will first define minimal CRM sequences driving expression of Msx genes in the dorsal CNS and then identify BMP-responsive sequences in these minimal CRMs and mutate them. In such CRM mutants we will then ask whether reporter gene expression is lost (i.e., BMPs positively regulate CRM activity) or is expanded into the adjacent epidermal domain (i.e., BMPs repress CRM activity). We will follow a similar strategy to identify and characterize CRMs driving expression of laterally (Pax6) and ventrally (Nkx2.2.) genes.
Funding Period: 2013-08-01 - 2014-07-31
more information: NIH RePORT

Detail Information

Research Grants30

  1. The Shelf Live Evaluation of Investigational Dosage Forms
    Jonathan White; Fiscal Year: 2013
    ..This contract is essential for continued assurance of the quality of drugs undergoing clinical investigation for different types of cancer by Cancer Therapeutics Evaluation Program. ..
  2. Glutamate receptor recruitment to new synapses in vivo
    PHILIP ERIC WASHBOURNE; Fiscal Year: 2013
    ..Our research will help understand the mechanisms by which synapses form and bring us closer to identifying the molecular deficits in individuals with autism and mental retardation. ..
  3. Gene regulatory network evolution and the origin of biological novelties
    MARK MARTINDALE; Fiscal Year: 2013
    ..These novel data will provide insight into the significance of variations in the GRNs in different systems and suggest specific gene interactions involved in abnormalities in endomesodermal development. ..
  4. Transcriptional regulation of neuronal differentiation
    Bennett G Novitch; Fiscal Year: 2013
  5. Developmental patterning of the anterior neural plate in a simple chordate
    Michael S Levine; Fiscal Year: 2013
  6. Mechanism of vertebrate neural tube morphogenesis
    John B Wallingford; Fiscal Year: 2013
    ..Experiments in Aim III will identify transcriptional activators of Shroom3 expression and lay the foundation for a gene regulatory network governing epithelial morphogenesis in vertebrates. Page 5 ..
  7. Regulation of CNS viral persistence
    Cornelia Bergmann; Fiscal Year: 2013
    ..Importantly, it will provide valuable information on the interactions of specific CNS cells involved in viral persistence and demyelination and the cellular and soluble mediators of the host immune response...
  8. BEN factors are conserved CSL co-repressors in Notch-mediated neural development
    Eric C Lai; Fiscal Year: 2013
    ..Overall, this proposal combines a variety of experimental approaches and model systems to investigate a novel conserved neural corepressor in the Notch pathway. ..
  9. Center for Integrative Neuroscience
    Michael A Webster; Fiscal Year: 2013
    ..abstract_text> ..
  10. COBRE for Skeletal Health and Repair
    Qian Chen; Fiscal Year: 2013
    ..This multidisciplinary approach is absolutely necessary to develop translational strategies for prevention and treatment of skeletal joint diseases. ..
  11. Regulation of polarity by Sonic hedgehog morphogen signaling
    Andrew P McMahon; Fiscal Year: 2013
  12. Hox Control of Cell-Specific EGF Signaling During Development
    Brian Gebelein; Fiscal Year: 2013
    ..Since the TFs and biological processes studied are highly conserved between flies and mammals, we are optimistic our mechanistic studies will continue to uncover new gene regulatory mechanisms relevant to human health and development. ..
  13. Transcriptome resources for a cephalopod model system
    Clifton W Ragsdale; Fiscal Year: 2013
    ..The generation of these transcriptomic and genomic resources will drive hypothesis-driven research on the molecular and cellular mechanisms of cephalopod development and regeneration. ..
    Steven M Anderson; Fiscal Year: 2013
    ..This concerted effort will provide mechanistic underpinnings for understanding lactation failure in women related to diabetes and/or obesity. ..
  15. Comparative Biology of Tissue Repair, Regeneration and Aging
    Kevin Strange; Fiscal Year: 2013
    ..The proposed COBRE will greatly enhance MDIBL's growth and development, which in turn will contribute to the continued growth and enhancement of the biomedical research infrastructure in Maine. ..
  16. Expanding Excellence in Developmental Biology in Oklahoma
    Linda F Thompson; Fiscal Year: 2013
    ..abstract_text> ..
  17. Cadiorenal and Metabolic Diseases Research Center
    John E Hall; Fiscal Year: 2013
    ..abstract_text> ..
  18. BMP signaling in vertebrate development
    Ken W Y Cho; Fiscal Year: 2013
    ..g., juvenile polyposis syndrome, primary pulmonary hypertension, Cowden's syndrome) and developmental abnormalities. Identification of candidate genes and signaling components will aid in developing new diagnosis and treatments. ..
  19. Mutational Analysis of Tunicate Development
    William Smith; Fiscal Year: 2013
    ..This proposal will examine the cellular and molecular mechanisms of early events in brain development using an animal that models human brain development. ..
    Chris Q Doe; Fiscal Year: 2013
    ..We have recently identified transcription factors expressed in sequentially in INPs, and we will determine if they specify temporal identity in these sublineages. ..
  21. A Cis-regulatory Model for Neural Border Induction
    Daniel Meulemans Medeiros; Fiscal Year: 2013
    ..The proposed work will support the training of one postdoctoral scholar for two years. ..
  22. Mechanisms of mechanical force evoked Ca2+ influx in developing neurons
    Patrick C Kerstein; Fiscal Year: 2013
    ..A better understanding of the molecular mechanisms through which calcium exerts such varied effects on growth cone motility will support treatment strategies for developmental disorders and neuronal injuries. ..
  23. Function of Toll-Like Receptors Throughout Gestation
    GIL G MOR; Fiscal Year: 2013
  24. Human Genome Sructural Variation
    Evan Eichler; Fiscal Year: 2013
    ..abstract_text> ..
  25. CSHL Neurobiology of Drosophila Course
    David J Stewart; Fiscal Year: 2013
    ..The course makes particular efforts to include a diverse group of participants, being particularly mindful of the inclusion of women, US minorities and a good balance of national and international scientists. ..
  26. Baylor Intellectual and Developmental Disabilities Research Center
    Huda Y Zoghbi; Fiscal Year: 2013
    ..abstract_text> ..