Mast cell tryptase controls paracellular permeability of the intestine -: Role of protease-activated receptor 2 and β-arrestins
Mast cell tryptase controls paracellular permeability of the intestine -: Role of protease-activated receptor 2 and β-arrestins
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DOI：
10.1074/jbc.m506338200
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发表时间：
2005-09-09
影响因子：
4.8
通讯作者：
Bunnett, NW
中科院分区：
文献类型：
--
作者：
Jacob, C;Yang, PC;Bunnett, NW
肠上皮细胞之间的紧密连接可防止管腔大分子和细菌进入，并防止炎症和感染。在应激和炎症过程中，肥大细胞通过未知机制介导粘膜通透性增加。我们假设肥大细胞类胰蛋白酶切割结肠细胞上的蛋白酶激活受体2（PAR 2）以增加细胞旁渗透性。结肠细胞表达PAR（2）mRNA，并对PAR（2）激动剂产生[Ca ~（2+）]（i）增加的反应。脱颗粒肥大细胞的上清液增加了结肠细胞中的[Ca 2 +]（i），这被类胰蛋白酶抑制剂阻止，并使对PAR 2激动剂的反应脱敏，表明PAR 2裂解。当应用于结肠细胞的基底外侧表面时，PAR 2激动剂和肥大细胞上清液降低跨上皮阻力，增加跨上皮大分子通量，并诱导紧密连接ZO-1和闭合蛋白和连接周围F-肌动蛋白的重新分布。当肥大细胞与结肠细胞共培养时，肥大细胞脱粒增加结肠细胞的细胞旁通透性。这是防止类胰蛋白酶抑制剂。我们确定了ERK 1/2和β-arrestins在PAR 2介导的渗透性改变中的作用，它们将ERK 1/2募集到核内体中的PAR 2，并将ERK 1/2保留在胞质溶胶中。ERK 1/2抑制剂可阻断PAR 2激动剂对F-actin通透性和再分布的影响。用小干扰RNA下调β-arrestins可抑制PAR 2诱导的ERK 1/2激活，并抑制PAR 2诱导的通透性变化。因此，肥大细胞通过类胰蛋白酶的释放和PAR 2的激活以旁分泌方式向结肠细胞发出信号。PAR 2与ERK 1/2的β-抑制蛋白依赖性激活偶联，ERK 1/2调节连接周围F-肌动蛋白的重组以增加上皮通透性。这些机制可以解释在应激和炎症期间肠上皮通透性增加。
Tight junctions between intestinal epithelial cells prevent ingress of luminal macromolecules and bacteria and protect against inflammation and infection. During stress and inflammation, mast cells mediate increased mucosal permeability by unknown mechanisms. We hypothesized that mast cell tryptase cleaves protease-activated receptor 2 (PAR2) on colonocytes to increase paracellular permeability. Colonocytes expressed PAR(2) mRNA and responded to PAR(2) agonists with increased [Ca2+](i). Supernatant from degranulated mast cells increased [Ca2+](i) in colonocytes, which was prevented by a tryptase inhibitor, and desensitized responses to PAR2 agonist, suggesting PAR2 cleavage. When applied to the basolateral surface of colonocytes, PAR2 agonists and mast cell supernatant decreased transepithelial resistance, increased transepithelial flux of macromolecules, and induced redistribution of tight junction ZO-1 and occludin and perijunctional F-actin. When mast cells were co-cultured with colonocytes, mast cell degranulation increased paracellular permeability of colonocytes. This was prevented by a tryptase inhibitor. We determined the role of ERK1/2 and of beta-arrestins, which recruit ERK1/2 to PAR2 in endosomes and retain ERK1/2 in the cytosol, on PAR2-mediated alterations in permeability. An ERK1/2 inhibitor abolished the effects of PAR2 agonist on permeability and redistribution of F-actin. Downregulation of beta-arrestins with small interfering RNA inhibited PAR2-induced activation of ERK1/2 and suppressed PAR2-induced changes in permeability. Thus, mast cells signal to colonocytes in a paracrine manner by release of tryptase and activation of PAR2. PAR2 couples to beta-arrestin-dependent activation of ERK1/2, which regulates reorganization of perijunctional F-actin to increase epithelial permeability. These mechanisms may explain the increased epithelial permeability of the intestine during stress and inflammation.