Trypsin activates pancreatic duct epithelial cell ion channels through proteinase-activated receptor-2
Trypsin activates pancreatic duct epithelial cell ion channels through proteinase-activated receptor-2
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DOI：
10.1172/jci2539
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发表时间：
1999-01-01
影响因子：
15.9
通讯作者：
Bunnett, NW
中科院分区：
文献类型：
--
作者：
Nguyen, TD;Moody, MW;Bunnett, NW
蛋白酶激活受体-2（PAR-2）是一种G蛋白偶联受体，其在NH 2末端被胰蛋白酶切割，暴露出结合并激活受体的拴系配体。我们研究了胰蛋白酶的分泌作用，通过PAR-2介导的，对分化良好的非转化犬胰管上皮细胞（PDEC）。胰蛋白酶和激活肽（AP或SLIGRL-NH 2，对应于PAR-2栓系配体）刺激I-125（-）外排（由Ca 2+激活的Cl-通道抑制剂抑制）和Rb-86（+）外排（由Ca 2+激活的Kt通道抑制剂抑制）。反向肽（LRGILS-NH 2）和抑制胰蛋白酶无活性。凝血酶没有影响，表明没有PAR-1，PAR-3，或PAR-4。在Ussing室，胰蛋白酶和AP刺激的短路电流从基底侧，但不是顶端，表面的PDEC单层。在单层透性基底或顶端制霉菌素，AP激活顶端Cl-和基底侧K+电导。PAR-2激动剂增加PDEC [Ca ~（2+）]（i），钙螯合剂BAPTA抑制AP的分泌作用。PAR-2在狗胰管和PDEC上的表达通过免疫荧光法验证。因此，胰蛋白酶与基底外侧PAR-2相互作用以增加[Ca 2 +]（i）并激活PDEC中的离子通道。在胰腺炎中，当胰蛋白酶原被过早激活时，PAR-2介导的导管分泌可促进毒素和碎片的清除。
Proteinase-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is cleaved by trypsin within the NH2-terminus, exposing a tethered ligand that binds and activates the receptor. We examined the secretory effects of trypsin, mediated through PAR-2, on well-differentiated nontransformed dog pancreatic duct epithelial cells (PDEC). Trypsin and activating peptide (AP or SLIGRL-NH2, corresponding to the PAR-2 tethered ligand) stimulated both an I-125(-) efflux inhibited by Ca2+-activated Cl- channel inhibitors and a Rb-86(+) efflux inhibited by a Ca2+-activated Kt channel inhibitor. The reverse peptide (LRGILS-NH2) and inhibited trypsin were inactive. Thrombin had no effect, suggesting absence of PAR-1, PAR-3, or PAR-4. In Ussing chambers, trypsin and AP stimulated a short-circuit current from the basolateral, but not apical, surface of PDEC monolayers. In monolayers permeabilized basolaterally or apically with nystatin, AP activated apical Cl- and basolateral K+ conductances. PAR-2 agonists increased [Ca2+](i) in PDEC, and the calcium chelator BAPTA inhibited the secretory effects of AP. PAR-2 expression on dog pancreatic ducts and PDEC was verified by immunofluorescence. Thus, trypsin interacts with basolateral PAR-2 to increase [Ca2+](i) and activate ion channels in PDEC. In pancreatitis, when trypsinogen is prematurely activated, PAR-2-mediated ductal secretion may promote clearance of toxins and debris.