Laboratory of Hereditary Kidney Diseases, INSERM, Paris, France.
Paris Descartes-Sorbonne Paris Cité University, Imagine Institute, Paris, France.
Hum Mol Genet. 2019 Aug 15;28(16):2720-2737. doi: 10.1093/hmg/ddz091.
Mutations in genes encoding components of the intraflagellar transport (IFT) complexes have previously been associated with a spectrum of diseases collectively termed ciliopathies. Ciliopathies relate to defects in the formation or function of the cilium, a sensory or motile organelle present on the surface of most cell types. IFT52 is a key component of the IFT-B complex and ensures the interaction of the two subcomplexes, IFT-B1 and IFT-B2. Here, we report novel IFT52 biallelic mutations in cases with a short-rib thoracic dysplasia (SRTD) or a congenital anomaly of kidney and urinary tract (CAKUT). Combining in vitro and in vivo studies in zebrafish, we showed that SRTD-associated missense mutation impairs IFT-B complex assembly and IFT-B2 ciliary localization, resulting in decreased cilia length. In comparison, CAKUT-associated missense mutation has a mild pathogenicity, thus explaining the lack of skeletal defects in CAKUT case. In parallel, we demonstrated that the previously reported homozygous nonsense IFT52 mutation associated with Sensenbrenner syndrome [Girisha et al. (2016) A homozygous nonsense variant in IFT52 is associated with a human skeletal ciliopathy. Clin. Genet., 90, 536-539] leads to exon skipping and results in a partially functional protein. Finally, our work uncovered a novel role for IFT52 in microtubule network regulation. We showed that IFT52 interacts and partially co-localized with centrin at the distal end of centrioles where it is involved in its recruitment and/or maintenance. Alteration of this function likely contributes to centriole splitting observed in Ift52-/- cells. Altogether, our findings allow a better comprehensive genotype-phenotype correlation among IFT52-related cases and revealed a novel, extra-ciliary role for IFT52, i.e. disruption may contribute to pathophysiological mechanisms.
先前,编码鞭毛内运输(IFT)复合物成分的基因突变与一类被称为纤毛病的疾病有关。纤毛病与纤毛的形成或功能缺陷有关,纤毛是大多数细胞表面存在的一种感觉或运动细胞器。IFT52 是 IFT-B 复合物的关键组成部分,可确保两个亚复合物 IFT-B1 和 IFT-B2 的相互作用。在此,我们报道了具有短肋胸发育不良(SRTD)或先天性肾和尿路异常(CAKUT)的病例中存在的 IFT52 双等位基因突变。通过结合在斑马鱼中的体外和体内研究,我们表明与 SRTD 相关的错义突变会损害 IFT-B 复合物的组装和 IFT-B2 纤毛定位,导致纤毛长度缩短。相比之下,与 CAKUT 相关的错义突变具有轻度的致病性,从而解释了 CAKUT 病例中缺乏骨骼缺陷的原因。同时,我们证明了先前报道的与 Sensenbrenner 综合征相关的纯合无义 IFT52 突变[Girisha 等人(2016 年)IFT52 中的纯合无义变异与人类骨骼纤毛病相关。Clin Genet.,90,536-539]导致外显子跳跃,并产生部分功能蛋白。最后,我们的工作揭示了 IFT52 在微管网络调节中的新作用。我们表明,IFT52 与 centrioles 远端的 centrin 相互作用并部分共定位,在此处它参与其募集和/或维持。这种功能的改变可能导致 Ift52-/-细胞中观察到的中心粒分裂。总之,我们的发现允许更好地对 IFT52 相关病例进行综合基因型-表型相关性分析,并揭示了 IFT52 的新的、细胞外的作用,即破坏可能有助于病理生理机制。
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