title: Analysis of Dickkopf3 interactions with Wnt signaling receptors.
abstract: Wnt signaling regulates essential biological processes ranging from embryogenesis to neurodegeneration. Recently, we demonstrated that Dickkopf3 (Dkk3) is a pro-survival glycoprotein that positively modulates Wnt signaling. An important step in understanding the mechanism of action of Dkk3 is identifying its interacting proteins in the Wnt pathway. In this study, we used a series of biochemical and functional assays to investigate the interaction between Dkk3 and the Wnt pathway receptors Kremen1 (Krm1), Kremen 2 (Krm2) and low-density lipoprotein receptor-related protein 6 (LRP6). Here, we report that, contrary to previous studies, Dkk3 interacts with Krm1 and Krm2. However, Dkk3 did not interact with, or alter expression of, LRP6. Blocking protein glycosylation did not alter the interaction between Dkk3 and Krm proteins. Additionally, Krm2 abolished Dkk3-mediated potentiation of Wnt signaling. Therefore, our data establish that Krm proteins are novel binding partners of Dkk3 and suggest a mechanism by which Dkk3 potentiates Wnt signaling.
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
authors.forename: Rei E I
authors.initials: RE
authors.lastname: Nakamura
authors.forename: Abigail S
authors.initials: AS
authors.lastname: Hackam
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D006031:Glycosylation; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D026502:LDL-Receptor Related Proteins / Q000378:metabolism; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D011485:Protein Binding; D018110:Receptors, Lipoprotein / Q000378:metabolism; D015398:Signal Transduction; D051153:Wnt Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D036341:Intercellular Signaling Peptides and Proteins; D026502:LDL-Receptor Related Proteins; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D008565:Membrane Proteins; D018110:Receptors, Lipoprotein; D051153:Wnt Proteins; C405061:Dkk3 protein, mouse; C486077:Kremen1 protein, mouse; C555475:LRP6 protein, human; C555476:Lrp6 protein, mouse