Downregulation of MDM2 stabilizes p53 by inhibiting p53 ubiquitination in response to specific alkylating agents

[摘要]

p53 is stabilized in response to DNA damaging stress. This stabilization is thought to result from phosphorylation in the N-terminus of p53, which inhibits p53:MDM2 binding, and prevents MDM2 from promoting p53 ubiquitination. In this report, the DNA alkylating agents mitomycin C (MMC) and methylmethane sulfonate (MMS), as well as UV radiation, stabilized p53 in a manner independent of phosphorylation in p53 N-terminus. This stabilization coincided with decreased levels of MDM2 mRNA and protein, and a corresponding decrease in p53 ubiquitination. Importantly, MDM2 overexpression inhibited the stabilization of p53 and decrease in ubiquitination following MMC, MMS, and UV treatment. This indicates that downregulation of MDM2 contributes to the stabilization of p53 in response to these agents.

[学科分类] 生物化学/生物物理

[关键词] Alkylating agent;Mitomycin C;Methylmethane sulfonate;p53;Murine double minute 2;Ubiquitination;BCNU;1;3-bis(2-chloroethyl)-1-nitrosourea;CDDP;cisplatin;DNA;deoxyribonucleic acid;cDNA;complementary DNA;EMS;ethylmethane sulfonate;EDTA;ethylenediaminetetraacetic acid;IR;ionizing radiation;MDM;murine double minute;MMC;mitomycin C;MMS;methylmethane sulfonate;MNNG;N-methyl-N′-nitro-N-nitrosoguanidine;4NQO;4-nitroquinoline-1-oxide;PMSF;phenylmethylsulfonyl fluoride;p53 N-term;mutant p53 in which S6;S9;S15;T18;S20;S33 and S37 are converted to alanine;RIPA;radioimmunoprecipitation assay;RNA;ribonucleic acid;mRNA;messenger RNA;SDS;sodium dodecyl sulfate;SSC;NaCl;sodium citrate;UV;ultraviolet rays