Abstract：
Best Vitelliform Macular dystrophy (BVMD) is the most prevalent of the distinctive retinal dystrophies caused by mutations in the BEST1 gene. This gene, which encodes for a homopentameric calcium-activated ion channel, is crucial for the homeostasis and function of the retinal pigment epithelia (RPE), the cell type responsible for recycling the visual pigments generated by photoreceptor cells. In BVMD patients, mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight. In this work, we employ iPSC-RPE cells derived from a patient with the p.Pro77Ser dominant mutation to determine the correlation between this variant and the ocular phenotype. To this purpose, gene and protein expression and localization are evaluated in iPSC-RPE cells along with functional assays like phagocytosis and anion channel activity. Our cell model shows no differences in gene expression, protein expression/localization, or phagocytosis capacity, but presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation. We hypothesize that this variant disturbs the neck region of the BEST1 channel, affecting channel function but maintaining cell homeostasis in the short term. This data shed new light on the different phenotypes of dominant mutations in BEST1, and emphasize the importance of understanding its molecular mechanisms. Furthermore, the data widen the knowledge of this pathology and open the door for a better diagnosis and prognosis of the disease.
摘要：
最佳卵形黄斑营养不良（BVMD）是由BEST1基因突变引起的最常见的独特视网膜营养不良。这个基因,编码同五聚体钙激活离子通道，对视网膜色素上皮（RPE）的稳态和功能至关重要，负责回收感光细胞产生的视觉色素的细胞类型。在BVMD患者中，该基因中的突变会导致RPE细胞层中的功能问题，并伴随着脂岩素的积累，从而演变成细胞死亡和视力丧失。在这项工作中,我们使用来自p.Pro77Ser显性突变患者的iPSC-RPE细胞来确定该变异与眼部表型之间的相关性.为此,在iPSC-RPE细胞中评估基因和蛋白质的表达和定位，以及吞噬作用和阴离子通道活性等功能测定。我们的细胞模型显示基因表达没有差异，蛋白质表达/定位，或吞噬能力，但呈现增加的氯化物入口，表明p.Pro77Ser变体可能是功能获得性突变。我们假设此变体会干扰BEST1通道的颈部区域，影响通道功能，但在短期内维持细胞稳态。这些数据为BEST1中显性突变的不同表型提供了新的启示，并强调了理解其分子机制的重要性。此外，这些数据扩大了对这种病理的认识，并为更好的诊断和预后打开了大门。
