Regulation of Bone Morphogenetic Protein Signaling by ADP-ribosylation

Yukihide Watanabe,Panagiotis Papoutsoglou,Varun Maturi,Yutaro Tsubakihara,Michael O Hottiger,Carl-Henrik Heldin,Aristidis Moustakas

doi:10.1074/jbc.m116.729699

Abstract

We previously established a mechanism of negative regulation of transforming growth factor β signaling mediated by the nuclear ADP-ribosylating enzyme poly-(ADP-ribose) polymerase 1 (PARP1) and the deribosylating enzyme poly-(ADP-ribose) glycohydrolase (PARG), which dynamically regulate ADP-ribosylation of Smad3 and Smad4, two central signaling proteins of the pathway. Here we demonstrate that the bone morphogenetic protein (BMP) pathway can also be regulated by the opposing actions of PARP1 and PARG. PARG positively contributes to BMP signaling and forms physical complexes with Smad5 and Smad4. The positive role PARG plays during BMP signaling can be neutralized by PARP1, as demonstrated by experiments where PARG and PARP1 are simultaneously silenced. In contrast to PARG, ectopic expression of PARP1 suppresses BMP signaling, whereas silencing of endogenous PARP1 enhances signaling and BMP-induced differentiation. The two major Smad proteins of the BMP pathway, Smad1 and Smad5, interact with PARP1 and can be ADP-ribosylated in vitro, whereas PARG causes deribosylation. The overall outcome of this mode of regulation of BMP signal transduction provides a fine-tuning mechanism based on the two major enzymes that control cellular ADP-ribosylation.

Highlights

We previously established a mechanism of negative regulation of transforming growth factor ␤ signaling mediated by the nuclear ADP-ribosylating enzyme poly-(ADP-ribose) polymerase 1 (PARP1) and the deribosylating enzyme poly-(ADPribose) glycohydrolase (PARG), which dynamically regulate ADP-ribosylation of Smad3 and Smad4, two central signaling proteins of the pathway
This study comes as a natural follow up of a series of recent reports that established for the first time that enzymes of the ADRT family, namely PARP1, PARP2, and PARG, regulate the flow and biological outcome of signal transduction by TGF-␤ [22,23,24,25, 27]
Because bone morphogenetic protein (BMP) pathways have distinct biological and molecular functions, we focused on the regulation of BMP signaling by PARP1 in the present paper

Summary

Introduction

We previously established a mechanism of negative regulation of transforming growth factor ␤ signaling mediated by the nuclear ADP-ribosylating enzyme poly-(ADP-ribose) polymerase 1 (PARP1) and the deribosylating enzyme poly-(ADPribose) glycohydrolase (PARG), which dynamically regulate ADP-ribosylation of Smad3 and Smad4, two central signaling proteins of the pathway. GR179307-2) was purchased from Abcam (Cambridge, UK) and used at 1:1,000 (v/v) dilution; the specificity of the antibody was verified based on the electrophoretic mobility of the protein, its loss after siRNA-mediated silencing, and its co-precipitation with Smad4 after BMP stimulation.

Results

Conclusion