The colon cancer tumor suppressor Adenomatous polyposis coli (APC) acts as an essential negative regulator of the Wnt signal transduction pathway and also has fundamental roles in the regulation of the actin and microtubule cytoskeletons. The precise mechanisms by which APC proteins influence the cytoskeleton have not been defined and may contribute to the development of colon cancer. We have developed an in vivo system in which to study the cytoskeletal functions of Drosophila APC2 using the Drosophila syncytial embryo as a model for cytoskeletal organization. Here, dynamic rearrangements of cortical actin during the cell cycle are orchestrated by a number of known actin regulatory proteins and by interactions with centrosomes and microtubules. We have previously shown that Drosophila APC2 plays a role in organization of the syncytial cytoskeleton in a complex including the Drosophila B-catenin homolog, Armadillo, and a-catenin. Our continued study of APC2 in this system revealed that APC2 functions to organize actin structures in the syncytial embryo and that this function is carried out in part with a Drosophila formin homology domain protein Diaphanous. The overall goals of this project include defining the molecular interactions of APC2 within the Armadillo-a-catenin complex and the Diaphanous complex and to understand in detail how these complexes are functioning to organize the actin cytoskeleton using biochemical assays, live imaging techniques, analysis of actin and microtubule organization and behavior, and identification of other proteins partners and regulators. These findings will contribute not only to our appreciation of normal cell processes, but also to our understanding of cellular dysfunction and cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM073891-03
Application #
7596849
Study Section
Cell Structure and Function (CSF)
Program Officer
Deatherage, James F
Project Start
2007-04-15
Project End
2012-03-31
Budget Start
2009-04-01
Budget End
2010-03-31
Support Year
3
Fiscal Year
2009
Total Cost
$250,533
Indirect Cost
Name
Carnegie-Mellon University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
052184116
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Kunttas-Tatli, Ezgi; Von Kleeck, Ryan A; Greaves, Bradford D et al. (2015) The two SAMP repeats and their phosphorylation state in Drosophila Adenomatous polyposis coli-2 play mechanistically distinct roles in negatively regulating Wnt signaling. Mol Biol Cell 26:4503-18
Kunttas-Tatli, Ezgi; Roberts, David M; McCartney, Brooke M (2014) Self-association of the APC tumor suppressor is required for the assembly, stability, and activity of the Wnt signaling destruction complex. Mol Biol Cell 25:3424-36
Jaiswal, Richa; Stepanik, Vince; Rankova, Aneliya et al. (2013) Drosophila homologues of adenomatous polyposis coli (APC) and the formin diaphanous collaborate by a conserved mechanism to stimulate actin filament assembly. J Biol Chem 288:13897-905
Kunttas-Tatli, Ezgi; Zhou, Meng-Ning; Zimmerman, Sandra et al. (2012) Destruction complex function in the Wnt signaling pathway of Drosophila requires multiple interactions between Adenomatous polyposis coli 2 and Armadillo. Genetics 190:1059-75
Zhou, Meng-Ning; Kunttas-Tatli, Ezgi; Zimmerman, Sandra et al. (2011) Cortical localization of APC2 plays a role in actin organization but not in Wnt signaling in Drosophila. J Cell Sci 124:1589-600
Zimmerman, Sandra G; Thorpe, Lauren M; Medrano, Vilma R et al. (2010) Apical constriction and invagination downstream of the canonical Wnt signaling pathway require Rho1 and Myosin II. Dev Biol 340:54-66
Webb, Rebecca L; Zhou, Meng-Ning; McCartney, Brooke M (2009) A novel role for an APC2-Diaphanous complex in regulating actin organization in Drosophila. Development 136:1283-93
Webb, Rebecca L; Rozov, Orr; Watkins, Simon C et al. (2009) Using total internal reflection fluorescence (TIRF) microscopy to visualize cortical actin and microtubules in the Drosophila syncytial embryo. Dev Dyn 238:2622-32