Neogenin, a Receptor for Bone Morphogenetic Proteins

Meiko Hagihara,Mitsuharu Endo,Katsuhiko Hata,Chikahisa Higuchi,Kunio Takaoka,Hideki Yoshikawa,Toshihide Yamashita

doi:10.1074/jbc.m110.180919

Abstract

Bone morphogenetic proteins (BMPs) regulate many mammalian physiologic and pathophysiologic processes. These proteins bind with the kinase receptors BMPR-I and BMPR-II, thereby activating Smad transcription factor. In this study, we demonstrate that neogenin, a receptor for netrins and proteins of the repulsive guidance molecule family, is a receptor for BMPs and modulates Smad signal transduction. Neogenin was found to bind directly with BMP-2, BMP-4, BMP-6, and BMP-7. Knockdown of neogenin in C2C12 cells resulted in the enhancement of the BMP-2-induced processes of osteoblastic differentiation and phosphorylation of Smad1, Smad5, and Smad8. Conversely, overexpression of neogenin in C2C12 cells suppressed these processes. Our results also indicated that BMP-induced activation of RhoA was mediated by neogenin. Inhibition of RhoA promoted BMP-2-induced processes of osteoblastic differentiation and phosphorylation of Smad1/5/8. However, treatment with Y-27632, an inhibitor of Rho-associated protein kinase, did not modulate BMP-induced phosphorylation of Smad1/5/8. Taken together, our findings suggest that neogenin negatively regulates the functions of BMP and that this effect of neogenin is mediated by the activation of RhoA.

Highlights

The results of the analysis showed that rhBMP-2 and rhBMP-4 bind directly with neogenin extracellular domain (ECD)
We investigated whether neogenin ECD interacted directly with rhBMP-2, rhBMP-4, rhBMP-6, and rhBMP-7 by performing an ELISA
Fc-tagged recombinant neogenin ECD (170 – 0 nM), Fc-tagged recombinant Bone morphogenetic proteins (BMPs) receptor type 1A (170 – 0 nM), Fc-tagged recombinant p75 (170 – 0 nM; p75 is a neurotrophin receptor belonging to the tumor necrosis factor receptor superfamily), or bovine serum albumin (BSA) was added to plastic wells coated with 0.1 mg/ml of one of the abovementioned rhBMPs

Summary

Introduction

Our results indicated that BMP-induced activation of RhoA was mediated by neogenin. This signal transduction negatively regulates BMP-induced osteoblastic differentiation of C2C12 cells. BMP-2 and BMP-4 were found to bind to cells expressing neogenin, but not those transfected with the control plasmid (Fig. 1A).

Results

Conclusion