Regulation of aquaporin-2 trafficking by vasopressin in the renal collecting duct -: Roles of ryanodine-sensitive Ca2+ stores and calmodulin
Regulation of aquaporin-2 trafficking by vasopressin in the renal collecting duct -: Roles of ryanodine-sensitive Ca2+ stores and calmodulin
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DOI：
10.1074/jbc.m005552200
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发表时间：
2000-11-24
影响因子：
4.8
通讯作者：
Knepper, MA
中科院分区：
文献类型：
--
作者：
Chou, CL;Yip, KP;Knepper, MA
在肾集管中，加压素通过触发水通道蛋白-2囊泡向根尖质膜的运输而增加渗透水通透性（P-f）。我们研究了抗利尿激素诱导的细胞内Ca2+动员在这一过程中的作用。在离体内髓集管（imcd）中，加压素（0.1 nM）和8-（4-氯苯硫基）-cAMP （0.1 mM）引起[Ca2+](i) （fluo-4）的显著增加，加压素诱导的Ca2+动员被预载Ca2+螯合剂BAPTA完全阻断，在平行实验中，BAPTA完全阻断加压素诱导的P-f的增加，而不影响腺苷3',5'-环单磷酸腺苷（cAMP）的产生。先前，我们证明了IMCD中抗利尿激素缺乏磷酸肌醇信号通路的激活，这表明肌醇1,4,5-三磷酸不依赖于Ca2+释放的机制。通过免疫荧光、免疫印迹和逆转录聚合酶链反应获得了I型ryanodine受体（RyR1）在IMCD中表达的证据。通过免疫荧光免疫细胞化学评估，ryanodine (100 muM)，一种ryanodine受体拮抗剂，阻断精氨酸抗利尿激素介导的P-f的增加，阻断抗利尿激素刺激的水通道蛋白-2在IMCD细胞原代培养中的再分配。钙调素抑制剂（W7和三氟拉嗪）阻断P-f对抗利尿激素的反应以及抗利尿激素刺激的水通道蛋白-2的再分配。结果表明，通过钙调素依赖机制，从红嘌呤敏感储存中释放Ca2+在抗利尿激素介导的水通道蛋白-2运输中起重要作用。
In the renal collecting duct, vasopressin increases osmotic water permeability (P-f) by triggering trafficking of aquaporin-2 vesicles to the apical plasma membrane. We investigated the role of vasopressin-induced intracellular Ca2+ mobilization in this process. In isolated inner medullary collecting ducts (IMCDs), vasopressin (0.1 nM) and 8-(4-chlorophenylthio)-cAMP (0.1 mM) elicited marked increases in [Ca2+](i) (fluo-4), Vasopressin-induced Ca2+ mobilization was completely blocked by preloading with the Ca2+ chelator BAPTA, In parallel experiments, BAPTA completely blocked the vasopressin-induced increase in P-f without affecting adenosine 3',5'-cyclic monophosphate (cAMP) production. Previously, we demonstrated the lack of activation of the phosphoinositide-signaIing pathway by vasopressin in IMCD, suggesting an inositol 1,4,5-trisphosphate-independent mechanism of Ca2+ release. Evidence for expression of the type I ryanodine receptor (RyR1) in IMCD was obtained by immunofluorescence, immunoblotting, and reverse transcription-polymerase chain reaction, Ryanodine (100 muM), a ryanodine receptor antagonist, blocked the arginine vasopressin-mediated increase in P-f and blocked vasopressin-stimulated redistribution of aquaporin-2 to the plasma membrane domain in primary cultures of IMCD cells, as assessed by immunofluorescence immunocytochemistry. Calmodulin inhibitors (W7 and trifluoperazine) blocked the P-f response to vasopressin and the vasopressin-stimulated redistribution of aquaporin-2. The results suggest that Ca2+ release from ryanodine-sensitive stores plays an essential role in vasopressin-mediated aquaporin-2 trafficking via a calmodulin-dependent mechanism.