Renal Division, University Freiburg Medical Center, Freiburg, Germany.
Hum Mol Genet. 2011 Aug 15;20(16):3119-28. doi: 10.1093/hmg/ddr214. Epub 2011 May 19.
NPHP4 mutations cause nephronophthisis, an autosomal recessive cystic kidney disease associated with renal fibrosis and kidney failure. The NPHP4 gene product nephrocystin-4 interacts with other nephrocystins, cytoskeletal and ciliary proteins; however, the molecular and cellular functions of nephrocystin-4 have remained elusive. Here we demonstrate that nephrocystin-4 is required for normal cloaca formation during zebrafish embryogenesis. Time-lapse imaging of the developing zebrafish pronephros revealed that tubular epithelial cells at the distal pronephros actively migrate between the yolk sac extension and the blood island towards the ventral fin fold to join the proctodeum and to form the cloaca. Nphp4-deficient pronephric duct cells failed to connect with their ectodermal counterparts, and instead formed a vesicle at the obstructed end of the pronephric duct. Nephrocystin-4 interacts with nephrocystin-1 and Par6. Depletion of zebrafish NPHP1 (nphp1) increased the incidence of cyst formation and randomization of the normal body axis, but did not augment cloaca malformation in nphp4-deficient zebrafish embryos. However, simultaneous depletion of zebrafish Par6 (pard6) aggravated cloaca formation defects in nphp4-depleted embryos, suggesting that nphp4 orchestrates directed cell migration and cloaca formation through interaction with the Par protein complex.
NPHP4 突变导致常染色体隐性遗传性多囊肾病，这是一种与肾纤维化和肾衰竭相关的囊性肾病。NPHP4 基因产物 nephrocystin-4 与其他 nephrocystins、细胞骨架和纤毛蛋白相互作用；然而，nephrocystin-4 的分子和细胞功能仍然难以捉摸。在这里，我们证明 nephrocystin-4 是斑马鱼胚胎发生过程中正常泄殖腔形成所必需的。对发育中的斑马鱼前肾进行延时成像显示，远端前肾的管状上皮细胞在前肾管和血岛之间积极迁移，向腹鳍褶移动，与原肠融合形成泄殖腔。Nphp4 缺陷的前肾导管细胞未能与它们的外胚层对应物连接，而是在前肾管的阻塞端形成一个囊泡。nephrocystin-4 与 nephrocystin-1 和 Par6 相互作用。斑马鱼 NPHP1（nphp1）的耗竭增加了囊肿形成的发生率和正常体轴的随机化，但并没有增加 nphp4 缺陷型斑马鱼胚胎的泄殖腔畸形。然而，斑马鱼 Par6（pard6）的同时耗竭加剧了 nphp4 耗尽胚胎中的泄殖腔形成缺陷，表明 nphp4 通过与 Par 蛋白复合物相互作用协调定向细胞迁移和泄殖腔形成。
