Physiological roles of cell surface ecto-enzymes

细胞表面胞外酶的生理作用

基本信息

批准号：
11694249
负责人：
KATADA Toshiaki
金额：
$ 4.42万
依托单位：
The University of Tokyo (Graduate School of Pharmaceutical Sciences)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11694249/
关键词：
lymphocytes CD38 ecto-enzyme NADase retinoic acid PC-1 phosphodiesterase

项目摘要

Ecto-form NADase activity induced by retinoic acid (RA) in human HL-60 cells is due to CD38, which has an amino acid sequence homologous to Aplysia ADP-ribosyl cyclase. CD38 catalyzes not only the hydrolysis of NAD^+, but also the formation and hydrolysis of cyclic ADP-ribose (cADPR), that is a novel mediator or modulator of Ca^<2+> release from intracellular Ca^<2+> stores. In the present study, we investigated the functions and properties of CD38 and its related ecto-enzyme, PC-1. 1. CD38 was capable of hydrolyzing the N-glycoside bond of many compounds other than NAD^+. 2. CD38 was abundantly present in rat astrocytes in addition to lymphocytes, and the cell-surface CD38 was rapidly inactivated upon incubation with the enzyme substrates. 3. Soluble and membrane-bound forms of PC-1, which had been induced in human Jurkat T cells upon culture with a cAMP analog, were identified and characterized enzymatically and structurally. 4. Both PC-1 molecules possessed phosphodiesterase/pyrophosphatase activity, and the enzymic activity of soluble PC-1 could be utilized to search for its interacting molecules. 5. Glycosaminoglycans, such as heparin and heparan sulfate in extracellular matrix, were capable of binding to PC-1 and inhibited its phosphodiesterase activity in a manner competing with the enzyme substrates. 6. A homologue of human PC-1 was also present in C.elegans, and it possessed phosphodiesterase/pyrophosphatase activity. The enzymic activity was localized in the cell surface. Thus, PC-1 may function as an adhesion molecule to associate with glycosaminoglycans in extracellular matrix.

人 HL-60 细胞中视黄酸 (RA) 诱导的外型 NADase 活性是由 CD38 引起的，CD38 具有与海兔 ADP-核糖基环化酶同源的氨基酸序列。 CD38不仅催化NAD^+的水解，还催化环ADP-核糖(cADPR)的形成和水解，cADPR是细胞内Ca^<2+>库释放Ca^<2+>的新型介质或调节剂。在本研究中，我们研究了 CD38 及其相关胞外酶 PC-1 的功能和特性。 1. CD38能够水解NAD^+以外的许多化合物的N-糖苷键。 2.除淋巴细胞外，大鼠星形胶质细胞中也大量存在CD38，并且细胞表面的CD38在与酶底物孵育后迅速失活。 3. PC-1 的可溶性和膜结合形式是在与 cAMP 类似物一起培养后在人 Jurkat T 细胞中诱导的，并在酶学和结构上进行了鉴定和表征。 4.两种PC-1分子均具有磷酸二酯酶/焦磷酸酶活性，可利用可溶性PC-1的酶活性来寻找其相互作用分子。 5.细胞外基质中的糖胺聚糖，如肝素和硫酸乙酰肝素，能够与PC-1结合，并以与酶底物竞争的方式抑制其磷酸二酯酶活性。 6. 人类PC-1的同源物也存在于秀丽隐杆线虫中，并且它具有磷酸二酯酶/焦磷酸酶活性。酶活性位于细胞表面。因此，PC-1可以作为粘附分子与细胞外基质中的糖胺聚糖结合。