The Wnt signal transduction pathway plays a critical role in many aspects of animal development as well as tumorigenesis in humans. The receptors for Wnts (Frizzled receptors) are predicted to contain seven transmembrane domains, reminiscent of G protein coupled receptors. Recently, genetic experiments in Drosophila and cultured mammalian cell experiments have implicated heterotrimeric G proteins in transduction of a Wnt signal. We propose to use biochemical approaches to elucidate the mechanisms by which G proteins transduce a Wnt signal. The proposed experiments take advantage of the capacity of Xenopus egg extracts to biochemically recapitulate complex reactions. Using this system, we recently reconstituted the cytoplasmic canonical arm of the Wnt pathway in order to study Wnt signal transduction in a cell-free system. This work led to a mathematical model of the Wnt pathway as well as a molecular description of how Wnt ligands transduce their signals inside the cell by promoting direct interaction of Dishevelled (Dsh) with the B-catenin degradation complex. We have now reconstituted signaling of the Wnt pathway from the level of G proteins (Goto and God) and we will systematically test other Ga subfamily members for their ability to activate the Wnt pathway in our biochemical system. We have shown that Wnt activation of the pathway by Goco is Dsh dependent, and we will determine whether Dsh interacts directly with Goco and will test Gao's ability to regulate downstream kinase activities. Finally, we propose to assess whether Goto functionally and physically interacts with the Frizzled receptor, Fz2.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM081635-04
Application #
7825257
Study Section
Molecular Neuropharmacology and Signaling Study Section (MNPS)
Program Officer
Dunsmore, Sarah
Project Start
2007-07-01
Project End
2012-04-30
Budget Start
2010-05-01
Budget End
2011-04-30
Support Year
4
Fiscal Year
2010
Total Cost
$230,902
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
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Li, Bin; Orton, Darren; Neitzel, Leif R et al. (2017) Differential abundance of CK1? provides selectivity for pharmacological CK1? activators to target WNT-dependent tumors. Sci Signal 10:
Ma, Yufang; Wang, Lihong; Neitzel, Leif R et al. (2017) The MAPK Pathway Regulates Intrinsic Resistance to BET Inhibitors in Colorectal Cancer. Clin Cancer Res 23:2027-2037
Lebensohn, Andres M; Dubey, Ramin; Neitzel, Leif R et al. (2016) Comparative genetic screens in human cells reveal new regulatory mechanisms in WNT signaling. Elife 5:
Astudillo, Luisana; Da Silva, Thiago G; Wang, Zhiqiang et al. (2016) The Small Molecule IMR-1 Inhibits the Notch Transcriptional Activation Complex to Suppress Tumorigenesis. Cancer Res 76:3593-603
Yang, Eungi; Tacchelly-Benites, Ofelia; Wang, Zhenghan et al. (2016) Wnt pathway activation by ADP-ribosylation. Nat Commun 7:11430
Wang, Zhenghan; Tacchelly-Benites, Ofelia; Yang, Eungi et al. (2016) Wnt/Wingless Pathway Activation Is Promoted by a Critical Threshold of Axin Maintained by the Tumor Suppressor APC and the ADP-Ribose Polymerase Tankyrase. Genetics 203:269-81
Hyde, Annastasia Simone; Hang, Brian I; Lee, Ethan (2016) Reconstitution of the Cytoplasmic Regulation of the Wnt Signaling Pathway Using Xenopus Egg Extracts. Methods Mol Biol 1481:101-9
Broadus, Matthew R; Chen, Tony W; Neitzel, Leif R et al. (2016) Identification of a Paralog-Specific Notch1 Intracellular Domain Degron. Cell Rep 15:1920-9
Saraswati, Sarika; Guo, Yan; Atkinson, James et al. (2015) Prolonged hypoxia induces monocarboxylate transporter-4 expression in mesenchymal stem cells resulting in a secretome that is deleterious to cardiovascular repair. Stem Cells 33:1333-44

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