Kuusniemi Arvi-Matti, Kestilä Marjo, Patrakka Jaakko, Lahdenkari Anne-Tiina, Ruotsalainen Vesa, Holmberg Christer, Karikoski Riitta, Salonen Riitta, Tryggvason Karl, Jalanko Hannu
Hospital for Children and Adolescents and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland.
Pediatr Res. 2004 May;55(5):774-81. doi: 10.1203/01.PDR.0000117842.10241.2C. Epub 2004 Feb 5.
Nephrin is a major component of the glomerular filtration barrier. Mutations in the nephrin gene (NPHS1) are responsible for congenital nephrotic syndrome of the Finnish type (NPHS1). Nephrin was at first thought to be podocyte specific, but recent studies have suggested that nephrin is also expressed in nonrenal tissues such as pancreas and CNS. We studied the expression of nephrin in human and porcine tissues at different stages of development and correlated these findings to clinical characteristics of NPHS1 children. Immunofluorescence staining and Western blotting were used to detect nephrin protein in frozen tissue samples. Polyclonal antibodies against the intracellular part of nephrin were used in these analyses. In situ hybridization was used to detect nephrin mRNA in specimens from normal human subjects and patients with NPHS1. Nephrin protein was not detected in nonrenal tissues obtained from human and porcine fetuses, newborns, and infants. Likewise, nephrin mRNA expression was not observed outside kidney glomerulus in normal or NPHS1 children. The phenotype analysis of NPHS1 children with severe nephrin gene mutations supported the findings in the tissue expression studies and revealed no impairment of the neurologic, testicular, or pancreatic function in a great majority of the patients. The studies suggest that nephrin has no major clinical significance outside the kidney.
Nephrin是肾小球滤过屏障的主要成分。Nephrin基因（NPHS1）突变是芬兰型先天性肾病综合征（NPHS1）的病因。Nephrin最初被认为是足细胞特异性的，但最近的研究表明，Nephrin也在非肾组织如胰腺和中枢神经系统中表达。我们研究了Nephrin在人类和猪不同发育阶段组织中的表达，并将这些发现与NPHS1患儿的临床特征相关联。采用免疫荧光染色和蛋白质免疫印迹法检测冷冻组织样本中的Nephrin蛋白。这些分析中使用了针对Nephrin细胞内部分的多克隆抗体。采用原位杂交法检测正常人和NPHS1患者标本中的Nephrin mRNA。在从人类和猪胎儿、新生儿及婴儿获取的非肾组织中未检测到Nephrin蛋白。同样，在正常或NPHS1患儿的肾小球外未观察到Nephrin mRNA表达。对具有严重Nephrin基因突变的NPHS1患儿进行的表型分析支持了组织表达研究的结果，并且在绝大多数患者中未发现神经、睾丸或胰腺功能受损。这些研究表明，Nephrin在肾脏外没有重大临床意义。
