Abstract
Mutations in human Adenomatous Polyposis Coli (APC) gene are associated with both familial and sporadic colorectal tumors. APC is known to down regulate beta-catenin levels, a transducer of Wnt signaling. The aim of this study is to provide transgenic Drosophila expressing either full-length or truncated forms of human APC (hAPC) protein and methods for using them in functional genomics and drug screening. Consistent with its biochemical properties, targeted expression of either full-length hAPC or its beta-catenin binding domain alone negatively regulated the function of the beta-catenin homologue, Armadillo (Arm) and thereby, inhibited Wnt/Wg signaling during fly development. hAPC inhibited Arm function even in the absence of GSK-3beta activity, although the latter was required to mediate the degradation of Arm. Consistent with this, hAPC suppressed the phenotypes induced by the over-expression of degradation-resistant forms of Arm. Subsequently, using hAPC-induced eye phenotypes as the assay in a suppressor-enhancer screen, we have identified two new loci in Drosophila, which modulate Wnt/Wg signaling. In addition, an anti-colon cancer drug, indomethacin, specifically enhanced hAPC-induced phenotypes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenomatous Polyposis Coli Protein / genetics
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Adenomatous Polyposis Coli Protein / physiology*
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Animals
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Animals, Genetically Modified
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Antineoplastic Agents / pharmacology
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Armadillo Domain Proteins
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Colorectal Neoplasms / drug therapy*
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Colorectal Neoplasms / genetics
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Cytoskeletal Proteins / physiology
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Drosophila / embryology
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Drosophila / genetics*
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Drosophila / metabolism
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Drosophila Proteins*
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Drug Screening Assays, Antitumor
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Eye / anatomy & histology
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Eye / embryology
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Eye / ultrastructure
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Gene Targeting
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Genes, APC*
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Genes, Insect
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Glycogen Synthase Kinase 3
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Humans
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Indomethacin / pharmacology
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Insect Proteins / physiology
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / physiology
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Trans-Activators*
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Transcription Factors
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Transfection
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Wnt1 Protein
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beta Catenin
Substances
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ARM protein, Drosophila
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Adenomatous Polyposis Coli Protein
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Antineoplastic Agents
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Armadillo Domain Proteins
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CTNNB1 protein, human
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Cytoskeletal Proteins
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Drosophila Proteins
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Insect Proteins
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Proto-Oncogene Proteins
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Trans-Activators
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Transcription Factors
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Wnt1 Protein
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beta Catenin
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wg protein, Drosophila
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Protein Serine-Threonine Kinases
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Sgg protein, Drosophila
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Calcium-Calmodulin-Dependent Protein Kinases
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Glycogen Synthase Kinase 3
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Indomethacin