水通道蛋白在多囊肾病小鼠肾囊泡上皮细胞的表达与调控

Expression and regulation of aquaporins in cystic epithelial cells of mice with polycystic kidney disease

目的探讨水通道蛋白（AQP）在多囊肾病囊泡上皮细胞的表达和调控。方法采用免疫荧光染色和Western印迹法分别检测不同亚型的水通道蛋白AQP1、AQP2、AQP3和AQP4在小鼠常染色体隐性遗传病jck多囊肾小鼠肾脏的表达定位和表达调控。结果8周龄jck纯合子小鼠的肾脏占体质量的百分率约是同窝野生型小鼠肾脏的4倍，肾脏组织出现多发、大小不一囊泡，囊泡上皮细胞呈扁平状，肾脏间质可见纤维化。jck小鼠血尿素水平为（42．6±6．7）mmol／L，约是野生型小鼠血尿素水平[（8．4±1．9）mmol／L]的5倍（P〈0．01）。免疫荧光定位分析结果表明AQP1在近曲小管上皮细胞顶膜和基底膜表达，也表达于髓袢降支细段和直小血管降支，肾囊泡上皮细胞未见AQP1表达。AQP2在集合管和肾囊泡上皮细胞顶膜表达，AQP3和AQP4在集合管和囊泡上皮细胞基底膜表达。Western印迹分析结果表明，jck肾脏AQP2、AQP3和AQP4蛋白表达水平与野生型肾脏相似，但AQPI在jck肾脏的表达水平显著低于其在野生型肾脏的表达水平（P〈0．01）。结论jck多囊。肾小鼠肾囊泡上皮表达AQP2、AQP3和AQP4，提示肾囊泡来源于肾集合管，水通道蛋白可能在肾囊泡生长过程中起重要作用。

Objective To study the expression and regulation of aquaporins （AQP） in cystic epithelial cells of jck mice with polyeystic kidney disease. Methods Localization and regulation of AQP1, AQP2, AQP3 and AQP4 protein were analyzed by using the immunofluorescenee and Western blotting. Results Kidneys of jek homozygous mice were 4 folds larger than those of litter matched wild-type mice. There were multiple cysts and fibrosis in the renal tissue of jck mice. The epithelial cells in cysts were flat in shape. Blood urea level in jck mice was （42.6 ± 6.7） mmol/L, which was 5 folds higher than that in wild-type mice [（8.4±1.9） mmol/L] （P〈0.01）. Immunofluorescence analysis showed that AQP1 was expressed in the apical and basolateral membranes of epithelial cells in proximal tubules, as well as in the thin descending limb of Henle and endothelial cells of descending vasa recta. There was no AQP1 expression in epithelial cells of cysts. AQP2 was expressed in the apical membranes of collecting ducts and renal cysts. AQP3 and AQP4 were expressed in basolateral membranes of collecting duct and renal cystic epithelial cells of jck mice. Western blot analysis showed the same protein sizes of AQP1, AQP2, AQP3 and AQP4 in both jck and wild-type kidneys. However, AQP1 expression was down-regulated in jck kidneys （P〈0.01）. Conclusion The renal cystic epithelia expresses AQP2, AQP3 and AQP4, which indicates that epithelial cells in renal cysts are derived from renal collecting ducts in jck mice and aquaporins may play an important role in renal cyst development.