Mdr1b facilitates p53-mediated cell death and p53 is required for Mdr1b upregulation in vivo
Mdr1b facilitates p53-mediated cell death and p53 is required for Mdr1b upregulation in vivo
复制标题
DOI：
10.1038/sj.onc.1204065
复制
发表时间：
2001-01-18
期刊：
影响因子：
8
通讯作者：
Schuetz, JD
中科院分区：
文献类型：
--
作者：
Lecureur, V;Thottassery, JV;Schuetz, JD
Mdr1b基因被认为是一种“应激反应”基因，但目前尚不清楚该基因是否在整个动物体内受P53的调控。此外，mdr1b的过度表达是否会影响细胞存活尚不清楚。在p53基因敲除小鼠中，评估了mdr1b对p53上调的依赖性。野生型(Wt)或p53-/-小鼠被单独或与伽玛射线(IR)和/或DNA损伤剂二乙基亚硝胺(DEN)联合处理，IR和DEN在野生型动物中诱导mdr1b，而在p53-/-小鼠中不处理。IR还上调H35肝细胞内源性MDR 1b的表达，MDR 1b启动子被IR激活，且激活与P53水平相关；此外，激活需要完整的P53结合位点。集落存活研究表明，与单独转导p53或单独转导mdr1b的细胞相比，同时转导mdr1b和p53的细胞克隆数显著减少；同时显微注射mdr1b和p53的细胞比单独注射其中一种表达载体的细胞活力损失更大。进一步用吖啶橙和溴化乙锭检测细胞凋亡的研究表明，mdr1b导致细胞凋亡，这一点被p53增强，但增加的凋亡需要一个功能性的p53反式激活结构域。这些研究表明，mdr1b是整个动物中P53的下游靶点，mdr1b的表达促进了P53介导的细胞死亡。
The mdr1b gene is thought to be a "stress-responsive" gene, however it is unknown if this gene is regulated by p53 in the whole animal. Moreover, it is unknown if overexpression of mdr1b affects cell survival. The dependence of mdr1b upon p53 for upregulation was evaluated in p53 knockout mice. Wild-type (wt) or p53-/- mice were treated singly or in combination with gamma irradiation (IR) and/or the potent DNA damaging agent, diethylnitrosoamine (DEN), Both IR and DEN induced mdr1b in wild-type animals, but not in the p53-/- mice. IR also upregulated endogenous mdr lb in the H35 liver cell line, and the mdr lb promoter was activated by IR and activation correlated with p53 levels; moreover activation required an intact p53 binding site. Colony survival studies revealed that co-transfection of both mdr1b and p53 dramatically reduced colony numbers compared to cells transfected with either p53 or mdr1b alone and cells microinjected with both mdr1b and p53 had a more dramatic loss in viability compared to cells injected with either expression vector alone. Further studies using acridine orange and ethidium bromide to measure apoptosis revealed that mdr1b caused apoptosis and this was enhanced by p53, however the increased apoptosis required a functional p53 transactivation domain. These studies indicate that mdr1b is a downstream target of p53 in the whole animal and expression of mdr1b facilitates p53-mediated cell death.