Regulation of platelet-activating factor receptor and PAF receptor-mediated arachidonic acid release by protein kinase C activation in rat Kupffer cells.
Regulation of platelet-activating factor receptor and PAF receptor-mediated arachidonic acid release by protein kinase C activation in rat Kupffer cells.
复制标题
大鼠 Kupffer 细胞中蛋白激酶 C 激活对血小板激活因子受体和 PAF 受体介导的花生四烯酸释放的调节。
DOI：
10.1016/0003-9861(90)90103-6
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发表时间：
1990
影响因子：
3.9
通讯作者：
Olson,MS
中科院分区：
文献类型：
--
作者：
Chao,W;Liu,H;Hanahan,DJ;Olson,MS
Phorbol 12-肉豆酸酯13-乙酸酯（PMA）是一种有效的蛋白激酶C激活剂，可引起大鼠Kupffer细胞质膜上血小板活化因子（AGEPC）受体的下调（降低40-50%），但对AGEPC受体结合亲和力的影响较小（Kd= 0.30 nm vs 0.56 nm），与细胞孵育较短时间（30-60 min）。结果，AGEPC受体介导的花生四烯酸释放减弱。PMA诱导AGEPC受体的下调具有浓度依赖性、特异性和短暂性（在1 h左右达到最大作用，在8.5 h内特异性[3H]AGEPC结合水平逐渐恢复到对照水平，添加PMA后24 h甚至高于对照水平）。从培养基中去除PMA后，在37°C下，超过一半的丢失受体在1小时内被替换，恢复过程似乎与蛋白质合成无关。在蛋白激酶C“下调”的细胞中，PMA下调AGEPC受体的能力丧失，这表明PMA的受体调节作用依赖于蛋白激酶C。蛋白激酶C可能参与了AGEPC诱导的花生四烯酸释放，因为1-（5-异喹啉磺酰）-2-甲基哌嗪二盐化蛋白激酶C抑制剂减弱了AGEPC在该系统中的刺激作用。此外，AGEPC诱导的[3H]花生四烯酸释放在蛋白激酶C下调的细胞中被显著抑制。本研究表明，蛋白激酶C在调节AGEPC介导的事件中具有双重作用，即正向作用，调节AGEPC刺激的花生四烯酸释放，以及负向作用，使AGEPC受体失活或下调。
Phorbol 12-myristate 13-acetate (PMA), a potent protein kinase C activator, caused down-regulation of receptors for platelet-activating factor (AGEPC) on the plasma membrane of rat Kupffer cells (40–50% reduction) but had a relatively minor effect on the binding affinity of the receptors for AGEPC (Kd= 0.30 nm vs 0.56 nm) when incubated with the cells for a short period of time (30–60 min). As a consequence, the AGEPC receptor-mediated arachidonic acid release was attenuated. The PMA-induced down-regulation of AGEPC receptors was concentration-dependent, specific, and transient (the maximal effect was observed at about 1 h and the level of specific [3H]AGEPC binding gradually returned to the control level within 8.5 h and even higher than the control level at 24 h after addition of PMA). Upon removing PMA from the culture medium, more than half of the lost receptors were replaced within 1 h at 37 °C and the recovery process appeared to be independent of protein synthesis. The ability of PMA to down-regulate the AGEPC receptors was lost in cells “down-regulated” for protein kinase C, suggesting that the receptor-regulatory effect of PMA is protein kinase C-dependent. Protein kinase C appeared to be involved in the AGEPC-induced arachidonic acid release since 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine dihydrochloride, a protein kinase C inhibitor, attenuated the stimulatory effect of AGEPC in this system. In addition, AGEPC-induced [3H]arachidonic acid release was inhibited significantly in cells down-regulated for protein kinase C. The present study thus demonstrates that protein kinase C has dual actions in the regulation of AGEPC-mediated events i.e., a positive forward action, regulating AGEPC-stimulated arachidonic acid release, and a negative action, which inactivates or down-regulates AGEPC receptors.