The E1B 19K/Bcl-2-binding protein Nip3 is a dimeric mitochondrial protein that activates apoptosis.
The E1B 19K/Bcl-2-binding protein Nip3 is a dimeric mitochondrial protein that activates apoptosis.
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DOI：
10.1084/jem.186.12.1975
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发表时间：
1997-12-15
期刊：
影响因子：
--
通讯作者：
Greenberg AH
中科院分区：
文献类型：
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作者：
Chen G;Ray R;Dubik D;Shi L;Cizeau J;Bleackley RC;Saxena S;Gietz RD;Greenberg AH
Nip 3（nineteenkD interacting protein-3）是一种功能未知的E1 B 19 K和Bcl-2结合蛋白。Nip 3在体内和体外均被检测为60-和30-kD蛋白，并且在酵母双杂交系统中表现出强烈的同源相互作用，表明它可以同源二聚化。Nip 3在线粒体中表达，并且缺乏推定的跨膜结构域和COOH末端的突变体（Nip 3163）不二聚化或定位于线粒体。在大鼠-1成纤维细胞和MCF-7乳腺癌中瞬时转染表位标记的Nip 3在12小时内诱导细胞凋亡，而转染Nip 3163突变体的细胞具有正常的表型，这表明线粒体定位是诱导细胞死亡所必需的。Nip 3过表达增加了对颗粒酶B和拓扑异构酶I和II抑制剂诱导的细胞凋亡的敏感性。转染后，Nip 3和Nip 3163蛋白水平均在48小时内稳定下降，表明蛋白质快速降解，并且这在不存在细胞死亡的情况下发生。Bcl-2过表达最初延迟Nip 3诱导的细胞凋亡的发生，但在较长的孵育时间内，抗性被完全克服。Nip 3蛋白水平高得多，并且在Bcl-2表达细胞中持续时间更长。总之，Nip 3是一种诱导细胞凋亡的二聚体线粒体蛋白，可以克服Bcl-2的抑制。
Nip3 (nineteen kD interacting protein-3) is an E1B 19K and Bcl-2 binding protein of unknown function. Nip3 is detected as both a 60- and 30-kD protein in vivo and in vitro and exhibits strong homologous interaction in a yeast two-hybrid system indicating that it can homodimerize. Nip3 is expressed in mitochondria and a mutant (Nip3163) lacking the putative transmembrane domain and COOH terminus does not dimerize or localize to mitochondria. Transient transfection of epitope-tagged Nip3 in Rat-1 fibroblasts and MCF-7 breast carcinoma induces apoptosis within 12 h while cells transfected with the Nip3163 mutant have a normal phenotype, suggesting that mitochondrial localization is necessary for induction of cell death. Nip3 overexpression increases the sensitivity to apoptosis induced by granzyme B and topoisomerase I and II inhibitors. After transfection, both Nip3 and Nip3163 protein levels decrease steadily over 48 h indicating that the protein is rapidly degraded and this occurs in the absence of cell death. Bcl-2 overexpression initially delays the onset of apoptosis induced by Nip3 but the resistance is completely overcome in longer periods of incubation. Nip3 protein levels are much higher and persist longer in Bcl-2 expressing cells. In conclusion, Nip3 is an apoptosis-inducing dimeric mitochondrial protein that can overcome Bcl-2 suppression.