Function of p73, not of p53, is inhibited by the physical interaction with RACK1 and its inhibitory effect is counteracted by pRB
Function of p73, not of p53, is inhibited by the physical interaction with RACK1 and its inhibitory effect is counteracted by pRB
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DOI：
10.1038/sj.onc.1206382
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发表时间：
2003-05
期刊：
影响因子：
8
通讯作者：
T. Ozaki;Ken-ichi Watanabe;T. Nakagawa;K. Miyazaki;M. Takahashi;A. Nakagawara
中科院分区：
文献类型：
--
作者：
T. Ozaki;Ken-ichi Watanabe;T. Nakagawa;K. Miyazaki;M. Takahashi;A. Nakagawara
新发现的p53相关基因p73编码一种核转录因子。与p53不同，p73有不同的异构体，具有不同的NH2-和COOH-末端。在p73的各种剪接异构体中，具有最长COOH末端延伸的p73α在许多组织和细胞中表达最为丰富，并且COOH末端区域似乎具有自我调节功能。为了分离和鉴定与p73cDNACOOH端相互作用的细胞蛋白(S)，我们采用酵母双杂交技术，以人胎脑和293细胞α文库为材料进行筛选。我们发现活化C激酶受体是p73α结合蛋白中的一个新成员。免疫共沉淀实验证实了RACK1与p53或p73β的相互作用。RACK1在SAOS-2细胞中的异位过表达降低了p73α介导的p53/p73反应启动子的转录，并抑制了p73α依赖的细胞凋亡。另一方面，RACK1不影响P53依赖的转录激活和细胞凋亡。此外，我们发现pRb在物理上与RACK1结合，并抑制依赖RACK1的p73α的抑制。综上所述，我们的观察表明，pRb通过与RACK1的相互作用来减弱RACK1介导的对p73α活性的抑制。
The newly identified p53-related gene, p73, encodes a nuclear transcription factor. Unlike p53, p73 has various isoforms with different NH 2-and COOH-terminal tails. p73α with the longest COOH-terminal extension is most abundantly expressed in many tissues and cells among those splicing isoforms of p73 and the COOH-terminal region appears to have an autoregulatory function. To isolate and characterize the cellular protein (s) that interacts with the unique COOH-terminal region of p73α, we employed a yeast two-hybrid screen with a human fetal brain and 293 cell cDNA libraries. We identified the receptor for activated C kinase (RACK1) as a new member of p73α-binding proteins. The interaction was confirmed by coimmunoprecipitation experiments, whereas RACK1 did not interact with p53 or p73β. Ectopic overexpression of RACK1 in SAOS-2 cells reduced the p73α-mediated transcription from the p53/p73-responsive promoters, and inhibited the p73α-dependent apoptosis. On the other hand, the p53-dependent transcriptional activation as well as apoptosis was unaffected in the presence of RACK1. Furthermore, we found that pRB physically bound to RACK1, and repressed the RACK1-dependent inhibition of p73α. Taken together, our observations suggest that pRB diminishes the RACK1-mediated inhibition of p73α activity through the interaction with RACK1.