Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Gl. Landevej 7, 2600 Glostrup, Denmark.
Int J Mol Sci. 2021 Jan 29;22(3):1345. doi: 10.3390/ijms22031345.
Bardet-Biedl syndrome (BBS) is a ciliopathy characterized by retinal dystrophy, renal cysts, obesity and polydactyly. BBS genes have been implicated in ciliogenesis, hedgehog signaling and retinal pigment epithelium maturation. BBS1 and BBS5 are members of the BBSome, implicated in cilia transport of proteins, and BBS10 is a member of the chaperonin-complex, mediating BBSome assembly. In this study, involvement of BBS1, BBS5 and BBS10 in ciliogenesis and hedgehog signaling were investigated in BBS-defective patient fibroblasts as well as in RPE-hTERT cells following siRNA-mediated knockdown of the BBS genes. Furthermore, the ability of BBS1-defective induced pluripotent stem-cells (iPSCs) to differentiate into RPE cells was assessed. We report that cells lacking functional BBS5 or BBS10 have a reduced number of primary cilia, whereas cells lacking functional BBS1 display shorter primary cilia compared to wild-type cells. Hedgehog signaling was substantially impaired and Smoothened, a component of hedgehog signaling, was trapped inside the cilia of the BBS-defective cells, even in the absence of Smoothened agonist. Preliminary results demonstrated the ability of BBS1-defective iPSC to differentiate into RPE-65 expressing RPE-like cells. The BBS1-defective RPE-like cells were less pigmented, compared to RPE-like cells differentiated from control iPSCs, indicating an impact of BBS1 on RPE maturation.
Bardet-Biedl 综合征（BBS）是一种纤毛病，其特征为视网膜营养不良、肾脏囊肿、肥胖和多指（趾）。BBS 基因与纤毛发生、刺猬信号和视网膜色素上皮成熟有关。BBS1 和 BBS5 是 BBSome 的成员，参与蛋白的纤毛运输，BBS10 是伴侣蛋白复合物的成员，介导 BBSome 的组装。在这项研究中，通过 BBS 基因的 siRNA 介导敲低，研究了 BBS 缺陷型患者成纤维细胞以及 RPE-hTERT 细胞中 BBS1、BBS5 和 BBS10 对纤毛发生和刺猬信号的影响。此外，还评估了 BBS1 缺陷型诱导多能干细胞（iPSC）分化为 RPE 细胞的能力。我们报告说，缺乏功能性 BBS5 或 BBS10 的细胞初级纤毛数量减少，而缺乏功能性 BBS1 的细胞初级纤毛比野生型细胞短。刺猬信号受到严重损害，刺猬信号的组成部分 Smoothened 被捕获在 BBS 缺陷型细胞的纤毛内，即使没有 Smoothened 激动剂也是如此。初步结果表明，BBS1 缺陷型 iPSC 分化为表达 RPE-65 的 RPE 样细胞的能力。与从对照 iPSC 分化而来的 RPE 样细胞相比，BBS1 缺陷型 RPE 样细胞的色素沉着较少，表明 BBS1 对 RPE 成熟有影响。
