TY - JOUR
T1 - Inhibition of MDM2-mediated p53 ubiquitination and degradation by ribosomal protein L5
AU - Dai, Mu Shui
AU - Lu, Hua
PY - 2004/10/22
Y1 - 2004/10/22
N2 - The oncoprotein MDM2 associates with ribosomal proteins L5, L11, and L23. Both L11 and L23 have been shown to activate p53 by inhibiting MDM2-mediated p53 suppression. Here we have shown that L5 also activates p53. Overexpression of L5 stabilized ectopic p53 in H1299 cells and endogenous p53 in U2OS cells. Consequently, L5 enhanced p53 transcriptional activity and induced p53-dependent G1 cell cycle arrest. Furthermore, like L11 and L23, L5 also remarkably inhibited MDM2-mediated p53 ubiquitination. The interaction of L5 with MDM2 was also enhanced by treatment with a low dose of actinomycin D. Actinomycin D-induced p53 was inhibited by small interference RNA against L5. By reciprocal co-immunoprecipitation, we further showed that there were at least two MDM2-ribosomal protein complexes in cells: MDM2-L5-L11-L23 and p53-MDM2-L5-L11-L23. We propose that the MDM2-L5-L11-L23 complex functions to inhibit MDM2-mediated p53 ubiquitination and thus activates p53.
AB - The oncoprotein MDM2 associates with ribosomal proteins L5, L11, and L23. Both L11 and L23 have been shown to activate p53 by inhibiting MDM2-mediated p53 suppression. Here we have shown that L5 also activates p53. Overexpression of L5 stabilized ectopic p53 in H1299 cells and endogenous p53 in U2OS cells. Consequently, L5 enhanced p53 transcriptional activity and induced p53-dependent G1 cell cycle arrest. Furthermore, like L11 and L23, L5 also remarkably inhibited MDM2-mediated p53 ubiquitination. The interaction of L5 with MDM2 was also enhanced by treatment with a low dose of actinomycin D. Actinomycin D-induced p53 was inhibited by small interference RNA against L5. By reciprocal co-immunoprecipitation, we further showed that there were at least two MDM2-ribosomal protein complexes in cells: MDM2-L5-L11-L23 and p53-MDM2-L5-L11-L23. We propose that the MDM2-L5-L11-L23 complex functions to inhibit MDM2-mediated p53 ubiquitination and thus activates p53.
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U2 - 10.1074/jbc.M403722200
DO - 10.1074/jbc.M403722200
M3 - Article
C2 - 15308643
AN - SCOPUS:7244238177
SN - 0021-9258
VL - 279
SP - 44475
EP - 44482
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 43
ER -