The cloned platelet thrombin receptor couples to at least two distinct effectors to stimulate phosphoinositide hydrolysis and inhibit adenylyl cyclase.
The cloned platelet thrombin receptor couples to at least two distinct effectors to stimulate phosphoinositide hydrolysis and inhibit adenylyl cyclase.
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DOI：
10.1016/s0021-9258(19)36762-6
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发表时间：
1992-10
期刊：
影响因子：
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通讯作者：
Deborah T. Hung;Y. Wong;T-Kh Vu;S. Coughlin
中科院分区：
文献类型：
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作者：
Deborah T. Hung;Y. Wong;T-Kh Vu;S. Coughlin
凝血酶既刺激磷酸肌苷水解，又抑制多种细胞类型的腺苷酸环化酶。克隆的人血小板凝血酶受体是否能解释这两种信号事件尚不清楚。我们报告了凝血酶受体激动剂肽在天然凝血酶反应的CCL-39细胞中引起磷酸肌肽水解和腺苷酸环化酶抑制。为了排除激动剂肽或凝血酶本身可能通过不同的受体激活这些途径的可能性，并避免缺乏合适的凝血酶受体缺失的细胞，我们使用了设计的“肠激酶受体”，一种凝血酶受体，其凝血酶切割识别序列LDPR被DDDDK取代，DDDDK是肠激酶切割识别序列。用这种结构转染肠激酶无反应的细胞，既能水解肠激酶敏感的磷酸肌肽，又能抑制腺苷酸环化酶。磷酸肌肽水解反应对百日咳毒素基本不敏感，而腺苷酸环化酶反应则被百日咳毒素完全阻断。这些数据表明，克隆的凝血酶受体可以通过至少两种不同的效应物，最有可能是gq样和gi样g蛋白，来影响磷酸肌苷水解和腺苷酸环化酶的抑制。
Thrombin both stimulates phosphoinositide hydrolysis and inhibits adenylyl cyclase in a variety of cell types. Whether the cloned human platelet thrombin receptor accounts for both of these signaling events is unknown. We report that thrombin receptor agonist peptide causes both phosphoinositide hydrolysis and inhibition of adenylyl cyclase in naturally thrombin-responsive CCL-39 cells. To exclude the possibility that the agonist peptide or thrombin itself may activate these pathways via distinct receptors and to circumvent a lack of suitable thrombin receptor-null cells, we utilized a designed “enterokinase receptor,” a thrombin receptor with its thrombin cleavage recognition sequence LDPR replaced by DDDDK, the enterokinase cleavage recognition sequence. Transfection of enterokinase-unresponsive cells with this construct conferred both enterokinase-sensitive phosphoinositide hydrolysis and inhibition of adenylyl cyclase. The phosphoinositide hydrolysis response was largely insensitive to pertussis toxin, whereas the adenylyl cyclase response was completely blocked by pertussis toxin. These data show that the cloned thrombin receptor can effect both phosphoinositide hydrolysis and inhibition of adenylyl cyclase via at least two distinct effectors, most likely Gq-like and Gi-like G-proteins.