title: The Poly(ADP-ribose) Polymerase Enzyme Tankyrase Antagonizes Activity of the β-Catenin Destruction Complex through ADP-ribosylation of Axin and APC2.
abstract: Most colon cancer cases are initiated by truncating mutations in the tumor suppressor, adenomatous polyposis coli (APC). APC is a critical negative regulator of the Wnt signaling pathway that participates in a multi-protein "destruction complex" to target the key effector protein β-catenin for ubiquitin-mediated proteolysis. Prior work has established that the poly(ADP-ribose) polymerase (PARP) enzyme Tankyrase (TNKS) antagonizes destruction complex activity by promoting degradation of the scaffold protein Axin, and recent work suggests that TNKS inhibition is a promising cancer therapy. We performed a yeast two-hybrid (Y2H) screen and uncovered TNKS as a putative binding partner of Drosophila APC2, suggesting that TNKS may play multiple roles in destruction complex regulation. We find that TNKS binds a C-terminal RPQPSG motif in Drosophila APC2, and that this motif is conserved in human APC2, but not human APC1. In addition, we find that APC2 can recruit TNKS into the β-catenin destruction complex, placing the APC2/TNKS interaction at the correct intracellular location to regulate β-catenin proteolysis. We further show that TNKS directly PARylates both Drosophila Axin and APC2, but that PARylation does not globally regulate APC2 protein levels as it does for Axin. Moreover, TNKS inhibition in colon cancer cells decreases β-catenin signaling, which we find cannot be explained solely through Axin stabilization. Instead, our findings suggest that TNKS regulates destruction complex activity at the level of both Axin and APC2, providing further mechanistic insight into TNKS inhibition as a potential Wnt pathway cancer therapy.
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Croy
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Caitlyn N
authors.initials: CN
authors.lastname: Fuller
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Jemma
authors.initials: J
authors.lastname: Giannotti
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Paige
authors.initials: P
authors.lastname: Robinson
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Andrew V A
authors.initials: AVA
authors.lastname: Foley
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Yamulla
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Sean
authors.initials: S
authors.lastname: Cosgriff
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Bradford D
authors.initials: BD
authors.lastname: Greaves
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Ryan A
authors.initials: RA
authors.lastname: von Kleeck
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Hyun Hyung
authors.initials: HH
authors.lastname: An
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Powers
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Julie K
authors.initials: JK
authors.lastname: Tran
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Tocker
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Jacob
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604.
authors.forename: Beckley K
authors.initials: BK
authors.lastname: Davis
authors.affiliation: From the Department of Biology, Franklin & Marshall College, Lancaster, Pennsylvania 17604. Electronic address: david.roberts@fandm.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Roberts
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D060466:Axin Protein / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D045325:HCT116 Cells; D006801:Humans; D008297:Male; D011485:Protein Binding; D013379:Substrate Specificity; D038501:Tankyrases / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000246:Adenosine Diphosphate Ribose; D060466:Axin Protein; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D038501:Tankyrases; D025521:Tumor Suppressor Proteins; D051176:beta Catenin; C467323:APC2 protein, Drosophila; C115681:APC2 protein, human; C418109:TNKS protein, human
keywords: ADP-ribosylation; Adenomatous Polyposis Coli; Tankyrase; Wnt signaling; XAV939; axin; beta-catenin (β-catenin); colon cancer; destruction complex