Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J1P3, Canada.
Mol Cell Endocrinol. 2010 Jul 29;323(2):232-8. doi: 10.1016/j.mce.2010.02.030. Epub 2010 Mar 1.
A role for the tight junction (TJ) protein occludin in the regulation of gill paracellular permeability was investigated using primary cultured "reconstructed" freshwater (FW) rainbow trout gill epithelia composed solely of pavement cells. Cortisol treatment reduced epithelial permeability characteristics, measured as changes in transepithelial resistance (TER) and paracellular [3H]PEG-4000 flux. Cortisol also reduced net Na+ flux rates when epithelia were exposed to apical FW. cDNA encoding for the TJ protein occludin was cloned from rainbow trout and found to be particularly abundant in gill tissue. In cultured gill preparations, occludin immunolocalized to the TJ complex and transcript abundance dose-dependently increased in response to cortisol treatment in association with reduced paracellular permeability. Occludin protein abundance also increased in response to cortisol treatment. However, occludin mRNA levels did not change in response to apical FW exposure, and [3H]PEG-4000 permeability did not decrease. These data support a role for occludin in the endocrine regulation of paracellular permeability across gill epithelia of fishes.
采用仅由扁平细胞组成的原代培养淡水（FW）虹鳟鱼鳃上皮“重建”物，研究了紧密连接（TJ）蛋白闭合蛋白在调节鳃上皮细胞旁通透性中的作用。皮质醇处理降低了上皮通透性特性，表现为跨上皮电阻（TER）和细胞旁[3H]PEG-4000 通量的变化。当上皮暴露于 FW 顶端时，皮质醇还降低了净 Na+通量率。从虹鳟鱼中克隆出编码 TJ 蛋白闭合蛋白的 cDNA，并发现其在鳃组织中特别丰富。在培养的鳃制剂中，闭合蛋白免疫定位到 TJ 复合物，并且转录丰度与皮质醇处理相关，与细胞旁通透性降低呈剂量依赖性增加。闭合蛋白蛋白丰度也响应皮质醇处理而增加。然而，occludin mRNA 水平对 FW 顶端暴露没有反应，并且[3H]PEG-4000 通透性没有降低。这些数据支持闭合蛋白在鱼类鳃上皮细胞旁通透性的内分泌调节中的作用。
