Hasegawa-Sasaki H, Lutz F, Sasaki T
Department of Biochemistry, Sapporo Medical College.
Microbiol Immunol. 1988;32(3):293-304. doi: 10.1111/j.1348-0421.1988.tb01389.x.
The CD3(T3)/antigen receptor complex appears to function by transducing an antigen signal presented by macrophages into the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. In order to find out how the CD3/antigen receptor complex regulates the hydrolysis of PtdIns(4,5)P2 to diacylglycerol and inositol trisphosphate, we investigated the possible role played by a guanine nucleotide-binding regulatory protein in PtdIns(4,5)P2 hydrolysis in a human T cell leukemia line, JURKAT. JURKAT cells were made permeable to Al3+, F-, GTP, and a nonhydrolyzable GTP analogue, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), by treatment with pseudomonal cytotoxin. In the presence of AlCl3 NaF stimulated the release of inositol phosphates in the cytotoxin-treated JURKAT cells. NaF plus AlCl3 induced increases in inositol tris-, bis-, and mono-phosphates and decreases in PtdIns(4,5)P2, phosphatidylinositol 4-phosphate, and phosphatidylinositol within 5 min after addition to the cytotoxin-treated cells at 37 C. GTP gamma S stimulated, to some extent, polyphosphoinositide hydrolysis in the cytotoxin-treated JURKAT. The cytotoxin-treated JURKAT cells retained the ability to respond to anti-Leu-4 with polyphosphoinositide hydrolysis. It has been shown that Al3+ in the presence of F- modulates the activity of various guanine nucleotide-binding regulatory proteins. Therefore, the results obtained in this study indicate that a guanine nucleotide-binding regulatory protein regulates the polyphosphoinositide breakdown in JURKAT cells by influencing phosphodiesterase activity.
CD3(T3)/抗原受体复合物似乎通过将巨噬细胞呈递的抗原信号转导为磷脂酰肌醇4,5 - 二磷酸[PtdIns(4,5)P2]的水解来发挥作用。为了弄清楚CD3/抗原受体复合物如何调节PtdIns(4,5)P2水解为二酰基甘油和肌醇三磷酸，我们研究了鸟嘌呤核苷酸结合调节蛋白在人T细胞白血病细胞系JURKAT中PtdIns(4,5)P2水解过程中可能发挥的作用。通过用铜绿假单胞菌细胞毒素处理，使JURKAT细胞对Al3 +、F -、GTP和一种不可水解的GTP类似物鸟苷5'-O-(3 - 硫代三磷酸)(GTPγS)具有通透性。在AlCl3存在的情况下，NaF刺激了经细胞毒素处理的JURKAT细胞中肌醇磷酸的释放。在37℃下将NaF加AlCl3添加到经细胞毒素处理的细胞中5分钟后，诱导了肌醇三磷酸、二磷酸和单磷酸的增加以及PtdIns(4,5)P2、磷脂酰肌醇4 - 磷酸和磷脂酰肌醇的减少。GTPγS在一定程度上刺激了经细胞毒素处理的JURKAT中的多磷酸肌醇水解。经细胞毒素处理的JURKAT细胞保留了通过多磷酸肌醇水解对抗Leu - 4作出反应的能力。已经表明，在F -存在的情况下Al3 +调节各种鸟嘌呤核苷酸结合调节蛋白的活性。因此，本研究获得的结果表明，鸟嘌呤核苷酸结合调节蛋白通过影响磷酸二酯酶活性来调节JURKAT细胞中的多磷酸肌醇分解。
