RGC32, a novel p53-inducible gene, is located on centrosomes during mitosis and results in G2/M arrest
RGC32, a novel p53-inducible gene, is located on centrosomes during mitosis and results in G2/M arrest
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DOI：
10.1038/sj.onc.1210148
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发表时间：
2007-02-22
期刊：
影响因子：
8
通讯作者：
Inazawa, J.
中科院分区：
文献类型：
--
作者：
Saigusa, K.;Imoto, I.;Inazawa, J.
为了确定恶性胶质瘤中经常观察到的13号染色体半合子缺失的靶基因，我们使用基于阵列的比较基因组杂交和使用寡核苷酸阵列的基因表达分析进行了全基因组DNA拷贝数分析。在13q14.11处的补体32应答基因（RGC 32）被鉴定为缺失靶点，并且与正常脑相比，其表达在胶质瘤细胞系中经常被沉默。RGC 32 mRNA水平在原发性星形细胞瘤的高级别中倾向于降低，尤其是在p53突变的肿瘤中。在p53突变的胶质瘤细胞系中，外源性p53显著增加了RGC 32 mRNA的表达，在p53（+/+）结肠癌细胞中，内源性p53也响应于DNA损伤而显著增加RGC 32 mRNA的表达，但在同基因p53（-/-）细胞中不增加。染色质免疫沉淀和报告基因分析表明，内源性p53蛋白的结合RGC 32基因的启动子区，这意味着p53依赖的转录活性。短暂和稳定过表达RGC 32抑制胶质瘤细胞的生长，可能是由于诱导G2/M期阻滞。免疫细胞化学分析显示RGC 32蛋白在有丝分裂过程中的中心体的浓度。RGC 32与polo样激酶1形成蛋白复合物，并在体外被磷酸化。这些观察结果暗示了一种新的机制，p53可能通过这种新发现的转录靶点负调控细胞周期进程。我们的研究结果提供了第一个证据表明，RGC 32可能是一个可能的肿瘤抑制胶质瘤，它是直接诱导的p53，它介导的有丝分裂进程的逮捕。
To identify target genes for the hemizygous deletions of chromosome 13 that are recurrently observed in malignant gliomas, we performed genome-wide DNA copy-number analysis using array-based comparative genomic hybridization and gene expression analysis using an oligonucleotide-array. The response gene to complement 32 (RGC32) at 13q14.11 was identified as a deletion target, and its expression was frequently silenced in glioma cell lines compared with normal brain. Levels of RGC32 mRNA tended to decrease toward higher grades of primary astrocytomas, especially in tumors with mutations of p53. Expression of RGC32 mRNA was dramatically increased by exogenous p53 in a p53-mutant glioma cell line, and also by endogenous p53 in response to DNA damage in p53(+/+) colon-cancer cells, but not in isogenic p53(-/-) cells. Chromatin immunoprecipitation and reporter assays demonstrated binding of endogenous p53 protein to the promoter region of the RGC32 gene, implying p53-dependent transcriptional activity. Transiently and stably overexpressed RGC32 suppressed the growth of glioma cells, probably owing to induction of G2/M arrest. Immunocytochemical analysis revealed a concentration of RGC32 protein at the centrosome during mitosis. RGC32 formed a protein complex with polo-like kinase 1 and was phosphorylated in vitro. These observations implied a novel mechanism by which p53 might negatively regulate cell-cycle progression by way of this newly identified transcriptional target. Our results provide the first evidence that RGC32 might be a possible tumor-suppressor for glioma, that it is directly induced by p53, and that it mediates the arrest of mitotic progression.