A cloned CCK-A receptor transduces multiple signals in response to full and partial agonists.
A cloned CCK-A receptor transduces multiple signals in response to full and partial agonists.
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DOI：
10.1152/ajpgi.1993.265.5.g999
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发表时间：
1993-11
期刊：
影响因子：
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通讯作者：
David I. Yule;Min-Jen Tseng;John A. Williams;C. D. Logdson
中科院分区：
文献类型：
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作者：
David I. Yule;Min-Jen Tseng;John A. Williams;C. D. Logdson
用稳定转染大鼠CCK-A受体的中国仓鼠卵巢(CHO)细胞，研究八肽胆囊收缩素(CCK-8)和部分激动剂JMV-180启动的信号转导事件。在负载Fura-2的单个CHO-CCK-A细胞中，灌流CCK-8(10 pm-1 nM)可引起细胞内钙离子浓度([Ca~(2+)]i)升高。在CCK-8浓度为100 pM时，信号由[Ca~(2+)]_i振荡组成。在较高浓度下，CCK-8诱导了一个典型的双相反应，包括一个大的峰值，然后是一个较低的持续平台。JMV-180灌流也导致细胞内[Ca~(2+)]i升高；与腺泡细胞不同，这种升高并不完全是由[Ca~(2+)]_i振荡引起的。CCK-8和JMV-180都促进了多聚磷脂酰肌醇的水解，尽管JMV-180只刺激了10%的[~3H]肌醇磷酸盐的形成。氨基类固醇U-73122可阻断CCK-8和JMV-180刺激的[Ca~(2+)]i信号。CCK-8(1-10 nM)可增加CHO-CCK细胞环磷酸腺苷(CAMP)的生成和花生四烯酸的释放。JMV-180(10微米)不能模拟这些增加。此外，当JMV-180和CCK-8共同孵育细胞时，没有检测到cAMP的形成和花生四烯酸的释放。这些结果表明，在CHO-CCK-A细胞中，与腺泡细胞不同，CCK-8和JMV-180通过相似的机制增加[Ca~(2+)]i。然而，CCK-A受体可以区别识别并激活这两种激动剂结合后的离散信号转导通路。
Chinese hamster ovary (CHO) cells, stably transfected with the cloned rat CCK-A receptor, were used to study signal transduction events initiated by cholecystokinin octapeptide (CCK-8) and the partial agonist JMV-180. In single CHO-CCK-A cells loaded with fura-2, superfusion of CCK-8 (10 pM-1 nM) resulted in an increase in intracellular Ca2+ concentration ([Ca2+]i). At CCK-8 concentrations < 100 pM, the signal consisted of [Ca2+]i oscillations. At higher concentrations, CCK-8 induced a typical biphasic response consisting of a large peak followed by a lower sustained plateau. Superfusion of JMV-180 also resulted in an increase in [Ca2+]i; in contrast to acinar cells this increase did not consist exclusively of [Ca2+]i oscillations. Both CCK-8 and JMV-180 increased polyphosphoinositide hydrolysis, although JMV-180 stimulated formation of only 10% as much [3H]inositol phosphates. [Ca2+]i signals stimulated by both CCK-8 and JMV-180 were blocked by the aminosteroid U-73122. CCK-8 (1-10 nM) increased formation of adenosine 3',5'-cyclic monophosphate (cAMP) and release of arachidonic acid in CHO-CCK cells. These increases were not mimicked by JMV-180 (10 microM). Furthermore, no cAMP formation or arachidonate release could be detected when cells were incubated with both JMV-180 and CCK-8. These data indicate that in CHO-CCK-A cells, unlike acinar cells, both CCK-8 and JMV-180 increase [Ca2+]i by similar mechanisms. However, the CCK-A receptor can differentially recognize and then activate discrete transduction pathways on binding of these two agonists.