Regulation of NUB1 Activity through Non-Proteolytic Mdm2-Mediated Ubiquitination

Thomas Bonacci; Stéphane Audebert; Luc Camoin; Emilie Baudelet; Juan-Lucio Iovanna; Philippe Soubeyran

doi:10.1371/journal.pone.0169988

Regulation of NUB1 Activity through Non-Proteolytic Mdm2-Mediated Ubiquitination

PLoS One. 2017 Jan 18;12(1):e0169988. doi: 10.1371/journal.pone.0169988. eCollection 2017.

Authors

Thomas Bonacci¹, Stéphane Audebert¹, Luc Camoin¹, Emilie Baudelet¹, Juan-Lucio Iovanna¹, Philippe Soubeyran¹

Affiliation

¹ Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, Marseille, France.

Abstract

NUB1 (Nedd8 ultimate buster 1) is an adaptor protein which negatively regulates the ubiquitin-like protein Nedd8 as well as neddylated proteins levels through proteasomal degradation. However, molecular mechanisms underlying this function are not completely understood. Here, we report that the oncogenic E3 ubiquitin ligase Mdm2 is a new NUB1 interacting protein which induces its ubiquitination. Interestingly, we found that Mdm2-mediated ubiquitination of NUB1 is not a proteolytic signal. Instead of promoting the conjugation of polyubiquitin chains and the subsequent proteasomal degradation of NUB1, Mdm2 rather induces its di-ubiquitination on lysine 159. Importantly, mutation of lysine 159 into arginine inhibits NUB1 activity by impairing its negative regulation of Nedd8 and of neddylated proteins. We conclude that Mdm2 acts as a positive regulator of NUB1 function, by modulating NUB1 ubiquitination on lysine 159.

MeSH terms

Adaptor Proteins, Signal Transducing
HEK293 Cells
Humans
Huntingtin Protein / genetics
Huntingtin Protein / metabolism
Lysine / metabolism
NEDD8 Protein
Proto-Oncogene Proteins c-mdm2 / genetics
Proto-Oncogene Proteins c-mdm2 / metabolism*
Transcription Factors / genetics
Transcription Factors / metabolism*
Ubiquitination
Ubiquitins / genetics
Ubiquitins / metabolism

Substances

Adaptor Proteins, Signal Transducing
HTT protein, human
Huntingtin Protein
NEDD8 Protein
NEDD8 protein, human
NUB1 protein, human
Transcription Factors
Ubiquitins
MDM2 protein, human
Proto-Oncogene Proteins c-mdm2
Lysine

Grants and funding

This work was supported by grants from INSERM, INCA, and La Ligue Contre le Cancer. TB was supported by a fellowship from La Ligue contre le Cancer and INSERM. EB was supported by Canceropôle PACA. The Marseille Proteomic facility (MaP; http://map.univmed.fr/) is supported by IBiSA (Infrastructures Biologie Santé et Agronomie), Canceropôle PACA, Région PACA and Institut Paoli-Calmettes. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.