Background

Ciliary dysfunction underlies a range of genetic disorders collectively termed ciliopathies, for which there are no treatments available. Bardet-Biedl syndrome (BBS) is characterised by multisystemic involvement, including rod-cone dystrophy and renal abnormalities. Together with Alström syndrome (AS), they are known as the ‘obesity ciliopathies’ due to their common phenotype. Nonsense mutations are responsible for approximately 11% and 40% of BBS and AS cases, respectively. Translational readthrough inducing drugs (TRIDs) can restore full-length protein bypassing in-frame premature termination codons, and are a potential therapeutic approach for nonsense-mediated ciliopathies.

Methods

Patient fibroblasts harbouring nonsense mutations from two different ciliopathies (Bardet-Biedl Syndrome and Alström Syndrome) were treated with PTC124 (ataluren) or amlexanox. Following treatment, gene expression, protein levels and ciliogenesis were evaluated. The expression of intraflagellar transport protein IFT88 and G-protein coupled receptor SSTR3 was investigated as a readout of ciliary function.

Findings

mRNA expression was significantly increased in amlexanox-treated patient fibroblasts, and full-length BBS2 or ALMS1 protein expression was restored in PTC124- and amlexanox-treated fibroblasts. Treatment with TRIDs significantly improved ciliogenesis defects in BBS2^Y24*/R275* fibroblasts. Treatment recovered IFT88 expression and corrected SSTR3 mislocalisation in BBS2^Y24*/R275* and ALMS1^{S1645*/S1645*} fibroblasts, suggesting rescue of ciliary function.

Interpretation

The recovery of full-length BBS2 and ALMS1 expression and correction of anatomical and functional ciliary defects in BBS2^Y24*/R275* and ALMS1^{S1645*/S1645*} fibroblasts suggest TRIDs are a potential therapeutic option for the treatment of nonsense-mediated ciliopathies.

中文翻译：

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纤毛病基因 BBS2 和 ALMS1 的翻译通读可恢复患者成纤维细胞的蛋白质、纤毛发生和功能

背景

纤毛功能障碍是一系列遗传疾病的基础，统称为纤毛病，目前尚无治疗方法。Bardet-Biedl 综合征 (BBS) 的特点是多系统受累，包括视杆细胞营养不良和肾脏异常。由于其共同的表型，它们与 Alström 综合征 (AS) 一起被称为“肥胖纤毛病”。无义突变分别导致大约 11% 和 40% 的 BBS 和 AS 病例。翻译通读诱导药物 (TRID) 可以恢复全长蛋白质，绕过框内过早终止密码子，并且是无义介导的纤毛病的潜在治疗方法。

方法

使用 PTC124 (ataluren) 或 amlexanox 治疗携带来自两种不同纤毛病（Bardet-Biedl 综合征和 Alström 综合征）的无义突变的患者成纤维细胞。处理后，评估了基因表达、蛋白质水平和纤毛发生。研究了鞭毛内转运蛋白 IFT88 和 G 蛋白偶联受体 SSTR3 的表达，作为纤毛功能的读数。

发现

氨来呫诺处理的患者成纤维细胞中 mRNA 表达显着增加，PTC124 和氨来呫诺处理的成纤维细胞中全长 BBS2 或 ALMS1 蛋白表达得到恢复。用 TRIDs 治疗可显着改善BBS2 ^Y24*/R275*成纤维细胞的纤毛发生缺陷。治疗恢复了 IFT88 表达并纠正了BBS2 ^Y24*/R275*和ALMS1 ^{S1645*/S1645*}成纤维细胞中的 SSTR3 错误定位，表明纤毛功能得以恢复。

解释

BBS2 ^Y24*/R275*和ALMS1 ^{S1645*/S1645*}成纤维细胞中全长 BBS2 和 ALMS1 表达的恢复以及解剖学和功能性纤毛缺陷的纠正表明 TRID 是治疗无意义介导的纤毛病的潜在治疗选择。