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The functions of DNA topoisomerase and genes regulated by DNA topology in differentiation.

DNA拓扑异构酶和受DNA拓扑调控的基因在分化中的功能。

基本信息

批准号：
10671750
负责人：
KIZAKI Harutoshi
金额：
$ 1.98万
依托单位：
TOKYO DENTAL COLLEGE
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671750/
关键词：
cellular differentiation DNA topoisomerase DNA topology TIS apoptosis salivary gland tumor cells PKCδ トポイソメラーゼ Pdcd4 H731 ヒト唾液腺腫瘍細胞 hnRNP A1 hnRNP Al

项目摘要

In cellular differentiation, various gene expression is regulated by altering DNA topology which is tightly modulated by DNA topoisomerase I and II.We identified two genes that were suppressed early in the incubation with topoisomerase inhibitors. One was highly homologous to hnRNPA1 which modulates splicing of selected transcripts or stabilizes mRNAs. The other was a novel gene, named as TIS, which spanned about 21 kb including 11 exons and was present as a single copy. It was expressed in most mouse tissues, but its function was unknown. Then, we analyzed the roles of topoisomerases and TIS gene in human salivary gland tumor cells (HSG) treated by differentiating agents such as topoisomerase inhibitor (etoposide), trans-retinoic acid (tRA) or dibutyryl cyclic AMP (bt2cAMP). Expression of topoisomerase I was reduced at the early state by tRA treatment but not by bt2cAMP.Expression of topoisomerase I was decreased by tRA, but at a lesser extent by bt2cAMP.The level of topoisomerase IIβ … More was low and was not altered. The results suggest that downregulation of topoisomerase IIα involves in arrest of cellular proliferation and initiation of differentiation through alterations in DNA topology. TIS gene expression was reduced at the early stage after the treatment of the agents, suggesting the involvement of TIS gene in differentiation. Recently, TIS has been known to play certain important role in neoplastic transformation, cytokine-induced T cell activation, neoplastic proliferation, and apoptosis.Apoptosis is induced as terminal differentiation in various cells inculuding salivary gland acinar cells. Salivary gland acinar cells and HSG cells underwent apoptosis by a topoisomerase II inhibitor, etoposide. PKCδ is known to be cleaved by caspase-3 in apoptotic cells. We found a novel isoform of PKCδ which was insensitive to caspase-3 in mouse salivary glands. These findings suggest that a novel PKCδ isoform may have some important role in terminal differentiation of salivary gland cells.Further studies are required to elucidate the role of topoisomerases and TIS gene using homogeneously differentiating cells as a model. Less

在细胞分化中，各种基因的表达是通过改变DNA拓扑结构来调节的，DNA拓扑异构酶I和II是紧密调节的。我们确定了两个基因，它们在与拓扑异构酶抑制剂孵育的早期被抑制。其中一个与hnRNPA 1高度同源，hnRNPA 1调节选定转录物的剪接或稳定mRNA。另一个是一个新基因，命名为TIS，它跨越约21 kb，包括11个外显子，以单拷贝存在。它在大多数小鼠组织中表达，但其功能尚不清楚。在此基础上，我们分析了拓扑异构酶抑制剂（依托泊苷）、反式维甲酸（tRA）和双丁酰环腺苷酸（bt 2cAMP）对人涎腺肿瘤细胞（HSG）分化过程中拓扑异构酶和TIS基因的作用。拓扑异构酶I的表达在tRA治疗的早期即被降低，而bt 2cAMP则无此作用;拓扑异构酶I的表达在tRA治疗后被降低，而bt 2cAMP的降低程度较轻;拓扑异构酶IIβ的表达在tRA治疗后被降低，而bt 2cAMP的降低程度较轻;拓扑异构酶IIβ的表达在tRA治疗后被降低，而bt 2cAMP的降低程度较轻。 ...更多信息很低，没有改变。结果表明，拓扑异构酶IIα的下调涉及通过改变DNA拓扑结构来阻止细胞增殖和启动分化。TIS基因表达在药物治疗后早期降低，提示TIS基因参与分化。近年来研究发现，TIS在肿瘤转化、肿瘤细胞增殖、肿瘤细胞活化及凋亡中发挥重要作用，其中凋亡可诱导包括涎腺腺泡细胞在内的多种细胞终末分化。拓扑异构酶II抑制剂依托泊苷可使唾液腺腺泡细胞和HSG细胞发生凋亡。已知PKCδ在凋亡细胞中被半胱天冬酶-3切割。我们在小鼠唾液腺中发现了一种对caspase-3不敏感的新型PKCδ亚型。提示PKCδ亚型可能在涎腺细胞的终末分化中起重要作用，但拓扑异构酶和TIS基因的作用还有待于进一步研究。少