Myocardial regulation of p300 and p53 by doxorubicin involves ubiquitin pathways
Myocardial regulation of p300 and p53 by doxorubicin involves ubiquitin pathways
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DOI：
10.1253/circj.cj-07-1076
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发表时间：
2008-09-01
影响因子：
3.3
通讯作者：
Hasegawa, Koji
中科院分区：
文献类型：
--
作者：
Morimoto, Tatsuya;Fujita, Masatoshi;Hasegawa, Koji
背景多柔比星(Dox)耗尽心肌细胞中的p300并诱导这些细胞的凋亡。P300蛋白对P53抑癌基因产物具有泛素连接酶活性，催化P53多聚体，并以泛素依赖的方式促进P53的降解。本研究探讨了Dox和p300对心肌细胞中P53泛素依赖的调节。方法和结果原代培养的新生大鼠心肌细胞暴露于蛋白酶体抑制剂MG132。MG132增加了这些细胞中p300和p53蛋白的水平，这表明泛素依赖的降解参与了这些蛋白的动态平衡。值得注意的是，用Dox处理心肌细胞降低了p300的蛋白水平，但显著增加了p53的蛋白水平。免疫沉淀-Western blotting结果显示，Dox处理后心肌细胞中多聚泛素化的p53蛋白表达减少，而p300蛋白的表达增加。最后，心肌细胞中p300的过表达除了抑制Dox诱导的细胞凋亡外，还抑制了Dox介导的P53水平的升高。结论Dox通过泛素依赖的途径相互调节P300和P53。通过其泛素连接酶的活性，部分参与了心肌细胞中泛素依赖的P53的降解。
Background Doxorubicin (Dox) depletes p300 from cardiac myocytes and induces apoptosis of these cells. p300 protein possesses ubiquitin ligase activity for the p53 tumor suppressor gene product, catalyzes p53 polyubiqutination, and facilitates p53 degradation in an ubiquitin-dependent manner. The present study investigated the ubiquitin-dependent regulation of p53 by Dox and p300 in cardiac myocytes.Methods and Results Primary cardiac myocytes from neonatal rats were exposed to a proteasome inhibitor, MG132, in Culture. MG132 increased both p300 and p53 protein levels in these cells, suggesting that ubiquitin-dependent degradation is involved in the homeostasis of these proteins. Notably, treatment of cardiac myocytes with Dox decreased the protein levels of p300 but markedly increased those of p53. By immunoprecipitation-Western blotting, it was shown that treatment with Dox decreased poly-ubiquitinated p53 but increased that of p300 in cardiac myocytes. Finally, the overexpression of p300 in cardiomyocytes suppressed the Dox-mediated increase in the p53 level in addition to inhibiting Dox-induced apoptosis.Conclusion Dox reciprocally regulates p300 and p53 through ubiquitin-dependent pathways and that p300. by its ubiquitin ligase activity, is partially involved in the ubiquitin-dependent degradation of p53 in cardiac myocytes.