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.

Keywords::

• Wnt signaling pathway
• Dickkopf3
• Kremen
• immunoprecipitation

Acknowledgments

We would like to express our appreciation to Ms Hyun Yi, Mr Amit Patel and Drs. Sanjoy Bhattacharya, George Brittain, and Wei Li.

Declaration of interest: This work was supported by a Research to Prevent Blindness Career Development award, Research to Prevent Blindness Unrestricted Grant (BPEI), the Karl Kirchgessner Foundation, and the National Eye Institute (NEI) (EY017837 and Departmental core grant P30EY014801). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.