The highly stereotyped tissue patterns that emerge during metazoan embryogenesis require precise spatial and temporal feedback regulation of key signal transduction pathways. Secreted Wnt proteins initiate intercellular signal transduction cascades that regulate cell morphology, execute cell fate decisions, and maintain stem cells. Altered Wnt signal transduction causes a growing list of diseases, including osteoporosis and dozens of types of cancer, and may contribute to the pathogenesis of several other diseases. The long-term goal of this proposal is to understand the mechanisms by which the effects of Wnt signals are spatially regulated during development. In the fruit fly Drosophila, the naked cuticle (nkd) gene is the only zygotic gene that spatially limits the effects of the Wnt signal Wingless (Wg) during early embryonic development. Nkd targets the Wnt signaling component Dishevelled (Dsh). Although the biochemical mechanisms of Dsh function are unknown, Dsh transmits signals from Frizzled (Fz) receptors to a large protein complex that triggers degradation of the Wnt effector and oncogene beta-catenin. Preliminary data indicate that Nkd may regulate Dsh phosphorylation, localization, and accumulation, each of which is important for Dsh function. The proposed experiments are designed to elucidate the molecular mechanism(s) by which Nkd limits Wnt signaling through Dsh in well-characterized tissues in a model genetic organism.
The specific aims are: 1) to determine the subcellular locus (loci) of Nkd action and its regulation during Wnt signaling in vivo; 2) to investigate the regulation and consequences of the biochemical interaction between Nkd, Dsh, and key Dsh-associated proteins; and 3) to discover additional regulator(s) of Nkd activity and begin to investigate their mechanism(s) of action. Because nkd is conserved in vertebrates, the proposed experiments will help create a new paradigm highly relevant to mammalian biology and disease. The potential health relevance of this project to developmental biology, stem cell biology, and disease-related research is substantial considering the wide employment of Wnt signaling throughout metazoan biology. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM065404-05
Application #
7254815
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Haynes, Susan R
Project Start
2003-07-01
Project End
2010-06-30
Budget Start
2007-07-01
Budget End
2010-06-30
Support Year
5
Fiscal Year
2007
Total Cost
$266,250
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Pathology
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Guo, Jianhui; Cagatay, Tolga; Zhou, Guangjin et al. (2009) Mutations in the human naked cuticle homolog NKD1 found in colorectal cancer alter Wnt/Dvl/beta-catenin signaling. PLoS One 4:e7982
Chan, Chih-Chiang; Zhang, Shu; Rousset, Raphael et al. (2008) Drosophila Naked cuticle (Nkd) engages the nuclear import adaptor Importin-alpha3 to antagonize Wnt/beta-catenin signaling. Dev Biol 318:17-28
Chan, Chih-Chiang; Zhang, Shu; Cagatay, Tolga et al. (2007) Cell-autonomous, myristyl-independent activity of the Drosophila Wnt/Wingless antagonist Naked cuticle (Nkd). Dev Biol 311:538-53
Zhang, Shu; Cagatay, Tolga; Amanai, Manami et al. (2007) Viable mice with compound mutations in the Wnt/Dvl pathway antagonists nkd1 and nkd2. Mol Cell Biol 27:4454-64
Waldrop, Sharon; Chan, Chih-Chiang; Cagatay, Tolga et al. (2006) An unconventional nuclear localization motif is crucial for function of the Drosophila Wnt/wingless antagonist Naked cuticle. Genetics 174:331-48