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Mol. Cells 2011; 32(3): 221-226

Published online September 30, 2011

https://doi.org/10.1007/s10059-011-1020-8

© The Korean Society for Molecular and Cellular Biology

PIAS1 Negatively Regulates Ubiquitination of Msx1 Homeoprotein Independent of Its SUMO Ligase Activity

Young Joon Song, and Hansol Lee*

Department of Biological Sciences, College of Natural Science, Inha University, Incheon 402-751, Korea

Correspondence to : *Correspondence: hlee@inha.ac.kr

Received: January 31, 2011; Revised: May 22, 2011; Accepted: June 8, 2011

Abstract

Posttranslational modifications play key roles in many cellular processes including proliferation and differentia-tion by modulating the activities of target proteins. PIAS1, a member of PIAS family of protein, mediates the modification of protein by SUMO and thereby regulates the function of its interacting protein partners. Here we report that PIAS1 negatively regulates ubiquitination of Msx1 homeoprotein, a regulator of myogenic differentiation, in a SUMO-independent manner. We demonstrate that ubiquitination and SUMOylation of Msx1 are not mutually exclusive but require the same C-terminal PIAS1 interaction domain. In addition, deletion of C-terminal domain increases the steady- state protein level of Msx1, while mutations of SUMO acceptor sites have no significant effect on the stability of Msx1 proteins. More-over, we find that forced expression of PIAS1 inhibits ubiquitination and thereby increases the stability of Msx1 protein regardless of its activity as a SUMO ligase. Furthermore, repressor activity of Msx1 in transcription is strengthened in the presence of PIAS1. Taken together, our studies uncover a new function of PIAS1, which is to control the stability of its interacting protein partner in a SUMO independent manner.

Keywords Msx1 homeoprotein, PIAS1, protein-protein interaction, SUMOylation, ubiquitination

Article

Research Article

Mol. Cells 2011; 32(3): 221-226

Published online September 30, 2011 https://doi.org/10.1007/s10059-011-1020-8

Copyright © The Korean Society for Molecular and Cellular Biology.

PIAS1 Negatively Regulates Ubiquitination of Msx1 Homeoprotein Independent of Its SUMO Ligase Activity

Young Joon Song, and Hansol Lee*

Department of Biological Sciences, College of Natural Science, Inha University, Incheon 402-751, Korea

Correspondence to:*Correspondence: hlee@inha.ac.kr

Received: January 31, 2011; Revised: May 22, 2011; Accepted: June 8, 2011

Abstract

Posttranslational modifications play key roles in many cellular processes including proliferation and differentia-tion by modulating the activities of target proteins. PIAS1, a member of PIAS family of protein, mediates the modification of protein by SUMO and thereby regulates the function of its interacting protein partners. Here we report that PIAS1 negatively regulates ubiquitination of Msx1 homeoprotein, a regulator of myogenic differentiation, in a SUMO-independent manner. We demonstrate that ubiquitination and SUMOylation of Msx1 are not mutually exclusive but require the same C-terminal PIAS1 interaction domain. In addition, deletion of C-terminal domain increases the steady- state protein level of Msx1, while mutations of SUMO acceptor sites have no significant effect on the stability of Msx1 proteins. More-over, we find that forced expression of PIAS1 inhibits ubiquitination and thereby increases the stability of Msx1 protein regardless of its activity as a SUMO ligase. Furthermore, repressor activity of Msx1 in transcription is strengthened in the presence of PIAS1. Taken together, our studies uncover a new function of PIAS1, which is to control the stability of its interacting protein partner in a SUMO independent manner.

Keywords: Msx1 homeoprotein, PIAS1, protein-protein interaction, SUMOylation, ubiquitination

Mol. Cells
Sep 30, 2022 Vol.45 No.9, pp. 603~672
COVER PICTURE
The Target of Rapamycin Complex (TORC) is a central regulatory hub in eukaryotes, which is well conserved in diverse plant species, including tomato (Solanum lycopersicum). Inhibition of TORC genes (SlTOR, SlLST8, and SlRAPTOR) by VIGS (virus-induced gene silencing) results in early fruit ripening in tomato. The red/ orange tomatoes are early-ripened TORC-silenced fruits, while the green tomato is a control fruit. Top, left, control fruit (TRV2-myc); top, right, TRV2-SlLST8; bottom, left, TRV2-SlTOR; bottom, right, TRV2-SlRAPTOR(Choi et al., pp. 660-672).

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