T84 cell receptor binding and guanyl cyclase activation by Escherichia coli heat-stable toxin.
T84 cell receptor binding and guanyl cyclase activation by Escherichia coli heat-stable toxin.
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大肠杆菌热稳定毒素对 T84 细胞受体的结合和鸟苷酸环化酶的激活。
DOI：
10.1152/ajpgi.1987.253.6.g775
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Giannella,R
中科院分区：
文献类型：
--
作者：
Guarino,A;Cohen,M;Thompson,M;Dharmsathaphorn,K;Giannella,R
大肠杆菌热稳定肠毒素 (STa) 通过与肠细胞受体结合并激活鸟苷酸环化酶 - 鸟苷 3',5'-环单磷酸 (cGMP) 系统来诱导肠道分泌。 STa 结合和分泌之间的中间步骤人们知之甚少，部分原因是缺乏一个方便的系统来研究 STa 在细胞水平上的影响。为了建立这样的模型，我们研究了 125I-STa 的结合、鸟苷酸环化酶的 STa 激活以及 STa 诱导的人结肠细胞系 T84 中 cGMP 产量的增加。结合是特异性的，与细胞数量成线性关系，并且依赖于时间、温度和 pH 值，并且是可逆的。 ST 也可能被这些细胞内化。添加未标记的 STa 竞争性抑制 125I-STa 的结合。这些参数与完整大鼠肠细胞和无细胞膜制剂中描述的参数非常相似。 STa 以剂量相关的方式刺激鸟苷酸环化酶和 cGMP 的产生。结合、STa 的鸟苷酸环化酶刺激和 cGMP 产生的相似剂量反应关系表明，鸟苷酸环化酶-cGMP 系统与特定受体的 ST 占据耦合。这些数据以及 STa 诱导 T84 细胞分泌氯离子的事实表明，T84 细胞是研究 STa 作用的细胞机制的合适且方便的系统。
Escherichia coli heat-stable enterotoxin (STa) induces intestinal secretion by binding to enterocyte receptors and activating the guanylate cyclase-guanosine 3',5'-cyclic monophosphate (cGMP) system. The intermediate steps between binding of STa and secretion are poorly understood, due in part to the lack of a convenient system to study the effects of STa at the cellular level. To establish such a model, we investigated the binding of 125I-STa, STa activation of guanylate cyclase, and STa-induced increase in cGMP production in a well-characterized human colonic cell line, T84. Binding was specific, linear with cell number, and time, temperature and pH dependent, and reversible. ST may also be internalized by these cells. Addition of unlabeled STa competitively inhibited binding of 125I-STa. These parameters closely resemble those described in intact rat enterocytes and cell-free membrane preparations. STa stimulated guanylate cyclase and cGMP production in a dose-related manner. The similar dose-response relationships for binding, guanylate cyclase stimulation by STa, and cGMP production suggest that the guanylate cyclase-cGMP system is coupled to ST occupancy of specific receptors. These data, together with the fact that STa induces chloride secretion from T84 cells suggest that T84 cells are a suitable and convenient system to study the cellular mechanism of action of STa.