PDF(Pubmed)
Abstract：
Fluid and solute transporters of the retinal pigment epithelium (RPE) are core components of the outer blood-retinal barrier. Characterizing these transporters and their role in retinal homeostasis may provide insights into ocular function and disease. Here, we describe RPE defects in tvrm77 mice, which exhibit hypopigmented patches in the central retina. Mapping and nucleotide sequencing of tvrm77 mice revealed a disrupted 5\' splice donor sequence in Slc4a5, a sodium bicarbonate cotransporter gene. Slc4a5 expression was reduced 19.7-fold in tvrm77 RPE relative to controls, and alternative splice variants were detected. SLC4A5 was localized to the Golgi apparatus of cultured human RPE cells and in apical and basal membranes. Fundus imaging, optical coherence tomography, microscopy, and electroretinography (ERG) of tvrm77 mice revealed retinal detachment, hypopigmented patches corresponding to neovascular lesions, and retinal folds. Detachment worsened and outer nuclear layer thickness decreased with age. ERG a- and b-wave response amplitudes were initially normal but declined in older mice. The direct current ERG fast oscillation and light peak were reduced in amplitude at all ages, whereas other RPE-associated responses were unaffected. These results link a new Slc4a5 mutation to subretinal fluid accumulation and altered light-evoked RPE electrophysiological responses, suggesting that SLC4A5 functions at the outer blood-retinal barrier.
摘要：
视网膜色素上皮（RPE）的液体和溶质转运蛋白是外部血液-视网膜屏障的核心组成部分。表征这些转运蛋白及其在视网膜稳态中的作用可以提供对眼功能和疾病的见解。这里,我们描述了tvrm77小鼠的RPE缺陷，在中央视网膜中表现出色素减退的斑块。tvrm77小鼠的作图和核苷酸测序揭示了碳酸氢钠协同转运蛋白基因Slc4a5中的5'剪接供体序列被破坏。相对于对照，tvrm77RPE中Slc4a5的表达减少了19.7倍，并检测到选择性剪接变体。SLC4A5定位于培养的人RPE细胞的高尔基体以及顶膜和基底膜。眼底成像,光学相干层析成像，显微镜,tvrm77小鼠的视网膜电图（ERG）显示视网膜脱离，与新生血管病变相对应的色素沉着斑块，和视网膜褶皱。随着年龄的增长，分离恶化，外核层厚度减小。ERGa-和b-波反应振幅最初是正常的,但在老年小鼠中下降。直流ERG快速振荡和光峰在所有年龄段的振幅都有所降低，而其他RPE相关反应未受影响。这些结果将新的Slc4a5突变与视网膜下液积聚和改变的光诱发RPE电生理反应联系起来，这表明SLC4A5在外血-视网膜屏障上发挥作用。
