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KMID : 0613820090190040436
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Journal of Life Science
2009 Volume.19 No. 4 p.436 ~ p.441
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The Stability of p53 in Ras-mediated Senescent Cells in Response to Nucleolar Stress
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Park Gil-Hong
Kim Sang-Hoon
Lee Kee-Ho
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Abstract
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B23/nucleophosmin, a nucleolar protein, translocates into the nucleus from the nucleolus when cells are damaged by extracellular stresses. Recently, it was shown that such translocation of B23/nucleophosmin in normal fibroblasts under stress conditions increases both the stability and activation of the p53 protein by disrupting its interaction with MDM2. Senescent cells have a single large nucleolus and a diminished capacity to induce p53 stability upon exposure to various DNA damaging agents. To investigate the role of B23/nucleophosmin in p53 stability in senescent cells, we established a senescence model system by expressing the ras oncogene in IMR90 cells. The stability of p53 was reduced in these cells in response to nucleolar stress, although the level of B23/nucleophosmin protein was not changed. In addition, p53 did not accumulate in the nucleus and B23/nucleophosmin did not translocate into the nucleoplasm. The binding affinity of B23/nucleophosmin with p53 was reduced in senescent cells, whereas the interaction between MDM2 and p53 was stable. Taken together, the stability of p53 in ras-induced senescent cells may be influenced by the ability of B23/nucleophosmin to interact with p53 in response to nucleolar stress.
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KEYWORD
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B23/nucleophosmin, senescence, p53, IMR90, nucleolar stress
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