Open AccessRegulation of tumor suppressor EAF2 polyubiquitination by ELL1 and SIAH2 in prostate cancer cells
Author(s) -
Xueying Yu,
Junkui Ai,
Liquan Cai,
Yifeng Jing,
Dan Wang,
Jun Dong,
Laura E. Pascal,
Jian Zhang,
Rong Luo,
Zhou Wang
Publication year - 2016
Publication title -
oncotarget
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.373
H-Index - 127
ISSN - 1949-2553
DOI - 10.18632/oncotarget.8588
Subject(s) - prostate cancer , cancer , medicine , china , geriatric oncology , gerontology , oncology , cancer research , family medicine , political science , law
RNA Polymerase II Elongation Factor (ELL)-associated factor 2 (EAF2) is a tumor suppressor frequently down-regulated in human prostate cancer. We previously reported that its binding partner ELL1 can enhance EAF2 protein stability and activity. Here we show that EAF2 can be polyubiquitinated and its degradation blocked by proteasome inhibitor. Co-immunoprecipitation detected EAF2 binding to SIAH2, an E3 ligase, and SIAH2 overexpression enhanced polyubiquitination of EAF2. Co-transfection of EAF2 binding partner ELL1 blocked EAF2 ubiquitination, providing a mechanism for EAF2 stabilization. Finally, EAF2K81R mutant, which exhibits reduced polyubiquitination and increased stability, was more potent than wild-type EAF2 in apoptosis induction. These findings suggest that SIAH2 is an E3 ligase for EAF2 polyubiquitination and ELL1 can enhance EAF2 level and function by blocking its polyubiquitination.