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Regulation of Cdk inhibitor p27 by Jab1.

Jab1 对 Cdk 抑制剂 p27 的调节。

基本信息

批准号：
12480216
负责人：
KATO Jun-ya
金额：
$ 9.22万
依托单位：
NARA INSTITUTE OF SCIENCE AND TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

Jab1, also known as the fifth component of the COP9 signalosome(CSN), plays an important role in a number of biological processes including cell cycle control. The core of the CSN complex is composed of eight subunits (CSN1-8), and disruption of one component results in loss of the whole complex. So far, two enzymatic activities are known to be associated with CSN. One is protein kinases (casein kinase II, protein kinase D, and 5/6 kinase), which regulate the stability of proteins such as c-Jun and p53 by direct phosphorylation. The others is a metalloprotease activity, which regulates the SCF ubiquitin ligase by removing the covalently-coupled, ubiquitin-like peptide, Nedd8, from the cullin subunit. Besides the 450-550-kDa CSN complex, Jab1 is also found as a smaller (ca 10 0 kDa)cytoplasmic complex. It remains to be determined which enzymatic activity and which form of the complex is responsible for a variety of biological responses connected to Jab1.To investigate the function of Ja … More b1 in vivo, we targeted the Jab1 locus by homologous recombination in mouse ES cells. No nullizygous mice were born live among 186 offspring of different Job1 heterozygous intercrosses, and the ratio of heterozygous mice to wild-type mice was 2.0 to 1, indicating that loss of Jab1 was embryonic lethal. Analysis of the embryos isolated from timed heterozygous intercrosses from embryonic day 8.5 to as early as E3.5 indicated that Jab1-/-embryos survived to the blastocyst Jab1-null embryonic cells, which also lacked other CSN components, expressed higher levels of p27, p53, and cyclin E, were positive for TUNEL assay and poorly incorporated BrdU, indicating that loss of Jab1 and the CSN complex results in impaired proliferation and accelerated apoptosis due to dysregulation of multiple cell cycle regulators. Interestingly, Jab1 heterozygous mice, although they were healthy and fertile, were smaller than the wild-type littermates. This was party due to less number of levels of p53, cyclin E and neddylated Cull were not changed. In these cells, the amount of Jab1-containing small complex but not that of CSN was selectively reduced. Cell cycle analysis of the synchronized MEFs showed that Jab1+/-MEFs failed to efficiently downregulate p27 during G1 and delayed the entry into S phase by 3 hours. Thus, these results suggest that Jab1 controls cell cycle progression in CSN-dependent and-independent ways. Less

Jab1也被称为COP9信号体（CSN）的第五组分，在包括细胞周期控制在内的许多生物过程中发挥重要作用。CSN复合体的核心由8个亚基（CSN1-8）组成，其中一个组分的破坏会导致整个复合体的损失。到目前为止，已知有两种酶活性与CSN有关。一种是蛋白激酶（酪蛋白激酶II、蛋白激酶D和5/6激酶），它们通过直接磷酸化来调节c-Jun和p53等蛋白的稳定性。另一个是金属蛋白酶活性，它通过去除cullin亚基上共价偶联的泛素样肽Nedd8来调节SCF泛素连接酶。除了450-550 kDa的CSN复合体，Jab1也被发现是一个较小的（约10 0 kDa）细胞质复合体。目前还不清楚是哪种酶活性和哪种形式的复合物导致了与Jab1相关的各种生物反应。为了研究Ja…More b1在体内的功能，我们在小鼠胚胎干细胞中对Jab1位点进行了同源重组。不同Job1杂合杂交的186个子代中，未见无合子小鼠存活，杂合小鼠与野生型小鼠的比值为2.0:1，说明Jab1缺失具有胚胎致死性。从胚胎第8.5天到第3.5天的时间杂合杂交中分离的胚胎分析表明，Jab1-/-胚胎存活到囊胚Jab1-null胚胎细胞，该胚胎细胞也缺乏其他CSN成分，表达更高水平的p27， p53和cyclin E， TUNEL检测阳性，BrdU掺入不良。这表明Jab1和CSN复合物的缺失导致多种细胞周期调节因子的失调导致增殖受损和细胞凋亡加速。有趣的是，Jab1杂合子小鼠虽然健康且有生育能力，但比野生型的幼崽要小。这部分是由于p53水平减少，细胞周期蛋白E和泛素化Cull没有改变。在这些细胞中，含有jab1的小复合物的量选择性减少，而不含CSN的量选择性减少。同步mef的细胞周期分析显示，Jab1+/- mef在G1期不能有效下调p27，并将进入S期的时间推迟了3小时。因此，这些结果表明，Jab1以csn依赖和独立的方式控制细胞周期进程。少