The Na/K-ATPase is obligatory for membrane anchorage of retinoschisin, the protein involved in the pathogenesis of X-linked juvenile retinoschisis
The Na/K-ATPase is obligatory for membrane anchorage of retinoschisin, the protein involved in the pathogenesis of X-linked juvenile retinoschisis
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DOI：
10.1093/hmg/ddq557
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发表时间：
2011-03-15
影响因子：
3.5
通讯作者：
Weber, Bernhard H. F.
中科院分区：
文献类型：
--
作者：
Friedrich, Ulrike;Stoehr, Heidi;Weber, Bernhard H. F.
编码含有视黄醇的盘状结构域的RS1基因突变会导致X连锁青少年视网膜裂解(XLRS)，这是一种男性常见的黄斑变性。视网膜各层结构紊乱和视网膜电信号异常是该病的特征，在缺乏同源小鼠蛋白的小鼠中也发现了这种现象，表明视黄醇对维持视网膜细胞的完整性很重要。在分泌时，维甲酸与光感受器和双极细胞的质膜结合，尽管蛋白质在体内与膜连接的成分尚不清楚。在这里，我们发现维甲酸不能与磷脂或单层脂泡结合。最近的蛋白质组学方法确定Na/K-ATPase亚基ATP1A3和ATP1B2是视黄蛋白的结合伙伴。我们分析了缺乏视黄醇(Rs1h(-/Y))和ATP1B2(Atp1b2(-/-))的小鼠，以表征Na/K-ATPase相互作用在视黄醇在细胞膜上的组织中的作用。我们发现，在Atp1b2(-/-)视网膜中，Na/K-ATPase和视黄醇蛋白都显著降低，这表明在没有ATP1A3和ATP1B2亚基的情况下，视黄醇蛋白膜的结合受到严重损害。相反，ATP1A3和ATP1B2的存在对于外源应用的视黄醇与粗膜的结合是必需的。此外，ATP1A3和ATP1B2的共同表达是维甲酸与完整的Hek293细胞结合所必需的。综上所述，我们的数据支持Na/K-ATPase在视网膜细胞表面锚定视黄醇的主要作用。此外，ATP1A3和ATP1B2的定位改变是维甲酸缺乏的一个显著后果，因此可能是XLRS细胞病理学的一个重要下游方面。
Mutations in the RS1 gene that encodes the discoidin domain containing retinoschisin cause X-linked juvenile retinoschisis (XLRS), a common macular degeneration in males. Disorganization of retinal layers and electroretinogram abnormalities are hallmarks of the disease and are also found in mice deficient for the orthologous murine protein, indicating that retinoschisin is important for the maintenance of retinal cell integrity. Upon secretion, retinoschisin associates with plasma membranes of photoreceptor and bipolar cells, although the components by which the protein is linked to membranes in vivo are still unclear. Here, we show that retinoschisin fails to bind to phospholipids or unilamellar lipid vesicles. A recent proteomic approach identified the Na/K-ATPase subunits ATP1A3 and ATP1B2 as binding partners of retinoschisin. We analyzed mice deficient for retinoschisin (Rs1h(-/Y)) and ATP1B2 (Atp1b2(-/-)) to characterize the role of Na/K-ATPase interaction in the organization of retinoschisin on cellular membranes. We demonstrate that both the Na/K-ATPase and retinoschisin are significantly reduced in Atp1b2(-/-) retinas, suggesting that retinoschisin membrane association is severely impaired in the absence of ATP1A3 and ATP1B2 subunits. Conversely, the presence of ATP1A3 and ATP1B2 are obligatory for binding of exogenously applied retinoschisin to crude membranes. Also, co-expression of ATP1A3 and ATP1B2 is required for retinoschisin binding to intact Hek293 cells. Taken together, our data support a predominant role of Na/K-ATPase in anchoring retinoschisin to retinal cell surfaces. Furthermore, altered localization of ATP1A3 and ATP1B2 is a notable consequence of retinoschisin deficiency and thus may be an important downstream aspect of cellular pathology in XLRS.