Jab1 induces the cytoplasmic localization and degradation of p53 in coordination with Hdm2.
The biological mechanisms for maintaining the basal level of p53 in normal cells require nuclear exclusion and cytoplasmic degradation. Here, we showed that Jab1 facilitates p53 nuclear exclusion and its subsequent degradation in coordination with Hdm2. p53 was excluded from the nucleus in the presence of Jab1; this exclusion was prevented by leptomycin B treatment. Nuclear export of p53 was accompanied by a decrease in the levels of p53, as well as of its target proteins, which include p21 and Bax. Domain analyses of Jab1 showed that the N-terminal domain, 1-110, was capable of inducing cytoplasmic translocation of p53. Furthermore, 110-191 was required to facilitate the degradation of p53. Neither of these mutants incorporated into the CSN complex, indicating that Jab1 could affect the levels of p53 independent of intact CSN complex. Conversely, Jab1 was incapable of translocating and degrading two p53 mutants, W23S and 6KR, neither of which could be modified by Hdm2. Moreover, Jab1 did not affect the cellular localization or protein levels of p53 in p53 and Hdm2 double-null mouse embryo fibroblasts. We further observed that the ablation of endogenous Jab1 by small interfering RNA prevented Hdm2-mediated p53 nuclear exclusion. Under stressed conditions, which could sequester Hdm2 in its inactive state, Jab1 did not affect p53. Our studies implicate that Jab1 is required to remove post-translationally modified p53 and provide a novel target for p53-related cancer therapies.
Oh
Wonkyung
W
Department of Food Science and Biotechnology, Faculty of Life Sciences and Technology, Sungkyunkwan University, Suwon 440-746.
Lee
Eun-Woo
EW
Department of Food Science and Biotechnology, Faculty of Life Sciences and Technology, Sungkyunkwan University, Suwon 440-746.
Sung
Young Hoon
YH
School of Biological Sciences, Seoul National University, Seoul 151-742; Department of Biochemistry, Yonsei University, Seoul 120-749, Korea.
Yang
Mi-Ran
MR
Department of Food Science and Biotechnology, Faculty of Life Sciences and Technology, Sungkyunkwan University, Suwon 440-746.
Ghim
Jaewang
J
Department of Food Science and Biotechnology, Faculty of Life Sciences and Technology, Sungkyunkwan University, Suwon 440-746.
Lee
Han-Woong
HW
Department of Biochemistry, Yonsei University, Seoul 120-749, Korea. Electronic address: hwl@yonsei.ac.kr.
Song
Jaewhan
J
Department of Food Science and Biotechnology, Faculty of Life Sciences and Technology, Sungkyunkwan University, Suwon 440-746. Electronic address: jso678@skku.edu.
D000818:Animals; D000075686:COP9 Signalosome Complex; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology*; D009154:Mutation; D010447:Peptide Hydrolases / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D047908:Intracellular Signaling Peptides and Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D010447:Peptide Hydrolases; C501488:COPS5 protein, human; C501490:Cops5 protein, mouse; D000075686:COP9 Signalosome Complex