Sharma Shiwani, Koh Katrina S Y, Collin Caitlin, Dave Alpana, McMellon Amy, Sugiyama Yuki, McAvoy John W, Voss Anne K, Gécz Jozef, Craig Jamie E
Department of Ophthalmology, Flinders University, Bedford Park, SA 5042, Australia.
Exp Cell Res. 2009 Aug 15;315(14):2358-72. doi: 10.1016/j.yexcr.2009.05.008. Epub 2009 May 15.
Mutations in the NHS (Nance-Horan Syndrome) gene lead to severe congenital cataracts, dental defects and sometimes mental retardation. NHS encodes two protein isoforms, NHS-A and -1A that display cell-type dependent differential expression and localization. Here we demonstrate that of these two isoforms, the NHS-A isoform associates with the cell membrane in the presence of intercellular contacts and it immunoprecipitates with the tight junction protein ZO-1 in MDCK (Madin Darby Canine Kidney) epithelial cells and in neonatal rat lens. The NHS-1A isoform however is a cytoplasmic protein. Both Nhs isoforms are expressed during mouse development. Immunolabelling of developing mouse with the anti-NHS antibody that detects both isoforms revealed the protein in the developing head including the eye and brain. It was primarily expressed in epithelium including neural epithelium and certain vascular endothelium but only weakly expressed in mesenchymal cells. In the epithelium and vascular endothelium the protein associated with the cell membrane and co-localized with ZO-1, which indirectly indicates expression of the Nhs-A isoform in these structures. Membrane localization of the protein in the lens vesicle similarly supports Nhs-A expression. In conclusion, the NHS-A isoform of NHS is a novel interactor of ZO-1 and may have a role at tight junctions. This isoform is important in mammalian development especially of the organs in the head.
NHS（南斯-霍兰综合征）基因突变会导致严重的先天性白内障、牙齿缺陷，有时还会导致智力发育迟缓。NHS编码两种蛋白质异构体，即NHS-A和-1A，它们表现出细胞类型依赖性的差异表达和定位。在这里，我们证明，在这两种异构体中，NHS-A异构体在存在细胞间接触的情况下与细胞膜结合，并在MDCK（麦迪逊-达比犬肾）上皮细胞和新生大鼠晶状体中与紧密连接蛋白ZO-1进行免疫共沉淀。然而，NHS-1A异构体是一种细胞质蛋白。两种Nhs异构体在小鼠发育过程中均有表达。用能检测这两种异构体的抗NHS抗体对发育中的小鼠进行免疫标记，结果显示该蛋白在包括眼睛和大脑在内的发育中的头部表达。它主要在上皮细胞中表达，包括神经上皮和某些血管内皮细胞，但在间充质细胞中表达较弱。在上皮细胞和血管内皮细胞中，该蛋白与细胞膜结合并与ZO-1共定位，这间接表明Nhs-A异构体在这些结构中的表达。该蛋白在晶状体泡中的膜定位同样支持Nhs-A的表达。总之，NHS的NHS-A异构体是ZO-1的一种新型相互作用蛋白，可能在紧密连接中发挥作用。这种异构体在哺乳动物发育中，尤其是头部器官的发育中很重要。
