Trigeminal ganglion development is a well studied model of vertebrate neurogenesis, where neural crest and placode cells come together to form this group of sensory neurons. Several genes are known to be expressed in cells contributing to the ganglion, but the function of most has not been elucidated. This proposal aims to characterize the function of key gene products expressed during the early stages of trigeminal placode and ganglion development. Research proposed here will focus on two genes expressed in neurogenic placode cells: Pax-3 and FGFR4. Early in their development, placode cells express Pax-3 as they become committed. FGFR4 expression peaks during placode cell delamination. Several other genes are subsequently expressed in the trigeminal placode, including Brn3a, neurogenin-2, and other downstream neuronal markers. A model is proposed whereby these genes govern the stepwise process of placode development.
The specific aims for this research are 1) determine the function of Pax-3 in trigeminal placode cell development, and 2) determine the function of FGFR4 in trigeminal placode cell development. Pax-3 and FGFR4 have been well studied in other embryonic model systems, providing a solid basis for experimental design. The results obtained from this research will be especially useful to neuroscientists, developmental and cancer biologist. The methods and experiments outlined in this proposal are based on extensive research showing that misexpression of genes in cells, tissues and live embryos is an effective approach to understanding cellular gene function. Preliminary data show the development and testing of misexpression and inhibitory constructs for these genes, which will be used in the chick embryo model system to fulfill the specific objectives. Proven techniques of gene misexpression will be utilized in this study, including RCAS retroviral mediated gene delivery and in ovo electroporation. The development of new reagents aimed at blocking gene expression including siRNA and morpholino technology have been successfully tested in our lab. Inhibition and misexpression experiments will be analyzed for cellular delamination, migration and proliferation, differentiation potential, and the expression of other important developmental genes. Important advances in our understanding of neuronal cell differentiation in development will be sought.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD046475-03
Application #
7213396
Study Section
Neurogenesis and Cell Fate Study Section (NCF)
Program Officer
Henken, Deborah B
Project Start
2005-07-26
Project End
2010-04-30
Budget Start
2007-05-01
Budget End
2008-04-30
Support Year
3
Fiscal Year
2007
Total Cost
$217,608
Indirect Cost
Name
Brigham Young University
Department
Physiology
Type
Schools of Arts and Sciences
DUNS #
009094012
City
Provo
State
UT
Country
United States
Zip Code
84602
Lassiter, Rhonda N T; Stark, Michael R; Zhao, Tianyu et al. (2014) Signaling mechanisms controlling cranial placode neurogenesis and delamination. Dev Biol 389:39-49
Adams, Jason S; Sudweeks, Sterling N; Stark, Michael R (2014) Pax3 isoforms in sensory neurogenesis: expression and function in the ophthalmic trigeminal placode. Dev Dyn 243:1249-61
Voelkel, Jacob E; Harvey, Jamison A; Adams, Jason S et al. (2014) FGF and Notch signaling in sensory neuron formation: a multifactorial approach to understanding signaling pathway hierarchy. Mech Dev 134:55-66
Lassiter, Rhonda N T; Ball, Matthew K; Adams, Jason S et al. (2010) Sensory neuron differentiation is regulated by notch signaling in the trigeminal placode. Dev Biol 344:836-48
Lassiter, Rhonda N T; Reynolds, Stephanie B; Marin, Kristopher D et al. (2009) FGF signaling is essential for ophthalmic trigeminal placode cell delamination and differentiation. Dev Dyn 238:1073-82
Dude, Carolynn M; Kuan, C-Y Kelly; Bradshaw, James R et al. (2009) Activation of Pax3 target genes is necessary but not sufficient for neurogenesis in the ophthalmic trigeminal placode. Dev Biol 326:314-26
Lassiter, Rhonda N T; Dude, Carolynn M; Reynolds, Stephanie B et al. (2007) Canonical Wnt signaling is required for ophthalmic trigeminal placode cell fate determination and maintenance. Dev Biol 308:392-406