BMB Reports 2017; 50(7): 373-378  https://doi.org/10.5483/BMBRep.2017.50.7.077
Phosphorylation of p53 at threonine 155 is required for Jab1-mediated nuclear export of p53
Eun-Woo Lee1, Wonkyung Oh2, Hosung Paul Song3 & Won Kon Kim1,*
1Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, 2DNA Repair Research Center, Chosun University School of Medicine, Gwangju 61452, 3Korea International School, Seongnam 13543, Korea
Correspondence to: Tel: +82-42-860-4265; Fax: +82-42-860-4149; E-mail: wkkim@kribb.re.kr
Received: May 11, 2017; Revised: May 24, 2017; Accepted: May 25, 2017; Published online: July 31, 2017.
© Korean Society for Biochemistry and Molecular Biology. All rights reserved.

Abstract
The Jun activation-domain binding protein 1 (Jab1) induces p53 nuclear export and cytoplasmic degradation, but the underlying mechanism is poorly understood. Here, we show that phosphorylation at the threonine 155 residue is essential for Jab1-mediated p53 nuclear export. Jab1 stimulated phosphorylation of p53 at T155 was inhibited by curcumin, an inhibitor of COP9 signalosome (CSN)-associated kinases. The T155E mutant, which mimics phosphorylated p53, exhibited spontaneous cytoplasmic localization in the absence of Jab1. This process was prevented by leptinomycin B (LMB), but not by curcumin. The substitution of threonine 155 for valine (T155V) abrogated Jab1-mediated p53 nuclear export, indicating that phosphorylation at this site is essential for Jab1-mediated regulation of p53. Although T155E can be localized in the cytoplasm in the absence of Mdm2, the translocation of T155E was significantly enhanced by ectopic Hdm2 expression. Our data suggests that Jab1-mediated phosphorylation of p53 at Thr155 residue mediates nuclear export of p53.
Keywords: COP9 signalosome, Curcumin, Hdm2, Jab1, p53


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