Ubiquitin-specific protease 11 functions as a tumor suppressor by modulating Mgl-1 protein to regulate cancer cell growth
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Key-Hwan Lim1, Bharathi Suresh1, Jung-Hyun Park1, Young-Soo Kim1, Suresh Ramakrishna1, Kwang-Hyun Baek1
1Department of Biomedical Science, CHA University, Gyeonggi-Do 463–400, Republic of Korea
Kwang-Hyun Baek, e-mail: [email protected]
Keywords: deubiquitinating enzyme, RanBPM, UAF1, ubiquitin, USP11
Received: August 30, 2015 Accepted: January 31, 2016 Published: February 22, 2016
The Lethal giant larvae (Lgl) gene encodes a cortical cytoskeleton protein, Lgl, and is involved in maintaining cell polarity and epithelial integrity. Previously, we observed that Mgl-1, a mammalian homologue of the Drosophila tumor suppressor protein Lgl, is subjected to degradation via ubiquitin-proteasome pathway, and scaffolding protein RanBPM prevents the turnover of the Mgl-1 protein. Consequently, overexpression of RanBPM enhances Mgl-1-mediated cell proliferation and migration. Here, we analyzed the ability of ubiquitin-specific protease 11 (USP11) as a novel regulator of Mgl-1 and it requires RanBPM to regulate proteasomal degradation of Mgl-1. USP11 showed deubiquitinating activity and stabilized Mgl-1 protein. However, USP11-mediated Mgl-1 stabilization was inhibited in RanBPM-knockdown cells. Furthermore, in the cancer cell migration, the regulation of Mgl-1 by USP11 required RanBPM expression. In addition, an in vivo study revealed that depletion of USP11 leads to tumor formation. Taken together, the results indicated that USP11 functions as a tumor suppressor through the regulation of Mgl-1 protein degradation via RanBPM.
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