Eley Lorraine, Gabrielides Christos, Adams Matthew, Johnson Colin A, Hildebrandt Friedhelm, Sayer John A
Institute of Human Genetics, International Centre for Life, Newcastle University, Newcastle Upon Tyne, UK.
Kidney Int. 2008 Nov;74(9):1139-49. doi: 10.1038/ki.2008.377. Epub 2008 Jul 16.
Joubert syndrome and related disorders are autosomal recessive multisystem diseases characterized by cerebellar vermis aplasia/hypoplasia, retinal degeneration and cystic kidney disease. There are five known genes; mutations of which give rise to a spectrum of renal cystic diseases the most common of which is nephronophthisis, a disorder characterized by early loss of urinary concentrating ability, renal fibrosis, corticomedullary cyst formation and renal failure. Many of the proteins encoded by these genes interact with one another and are located at adherens junctions or the primary cilia and or basal bodies. Here we characterize Jouberin, a multi-domain protein encoded by the AHI1 gene. Immunohistochemistry with a novel antibody showed that endogenous Jouberin is expressed in brain, kidney and HEK293 cells. In the kidney, Jouberin co-localized with aquaporin-2 in the collecting ducts. We show that Jouberin interacts with nephrocystin-1 as determined by yeast-2-hybrid system and this was confirmed by exogenous and endogenous co-immunoprecipitation in HEK293 cells. Jouberin is expressed at cell-cell junctions, primary cilia and basal body of mIMCD3 cells while a Jouberin-GFP construct localized to centrosomes in subconfluent and dividing MDCK cells. Our results suggest that Jouberin is a protein whose expression pattern supports both the adherens junction and the ciliary hypotheses for abnormalities leading to nephronophthisis.
乔布综合征及相关疾病是常染色体隐性遗传的多系统疾病，其特征为小脑蚓部发育不全/发育不良、视网膜变性和多囊肾病。已知有五个基因，这些基因的突变会引发一系列肾囊性疾病，其中最常见的是肾单位肾痨，其特征为早期尿浓缩能力丧失、肾纤维化、皮质髓质囊肿形成和肾衰竭。这些基因编码的许多蛋白质相互作用，位于黏着连接、初级纤毛或基体处。在此，我们对由AHI1基因编码的多结构域蛋白乔布素进行了表征。用一种新型抗体进行的免疫组织化学显示，内源性乔布素在脑、肾和HEK293细胞中表达。在肾脏中，乔布素在集合管中与水通道蛋白-2共定位。我们通过酵母双杂交系统证明乔布素与肾囊肿蛋白-1相互作用，这在HEK293细胞的外源性和内源性共免疫沉淀中得到了证实。乔布素在mIMCD3细胞的细胞间连接、初级纤毛和基体处表达，而乔布素-绿色荧光蛋白构建体在亚汇合和分裂的MDCK细胞中定位于中心体。我们的结果表明，乔布素是一种蛋白质，其表达模式支持导致肾单位肾痨异常的黏着连接和纤毛假说。
