Damerla Rama Rao, Cui Cheng, Gabriel George C, Liu Xiaoqin, Craige Branch, Gibbs Brian C, Francis Richard, Li You, Chatterjee Bishwanath, San Agustin Jovenal T, Eguether Thibaut, Subramanian Ramiah, Witman George B, Michaud Jacques L, Pazour Gregory J, Lo Cecilia W
Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Department of Cell and Developmental Biology and.
Hum Mol Genet. 2015 Jul 15;24(14):3994-4005. doi: 10.1093/hmg/ddv137. Epub 2015 Apr 15.
Recent studies identified a previously uncharacterized gene C5ORF42 (JBTS17) as a major cause of Joubert syndrome (JBTS), a ciliopathy associated with cerebellar abnormalities and other birth defects. Here we report the first Jbts17 mutant mouse model, Heart Under Glass (Hug), recovered from a forward genetic screen. Exome sequencing identified Hug as a S235P missense mutation in the mouse homolog of JBTS17 (2410089e03rik). Hug mutants exhibit multiple birth defects typical of ciliopathies, including skeletal dysplasia, polydactyly, craniofacial anomalies, kidney cysts and eye defects. Some Hug mutants exhibit congenital heart defects ranging from mild pulmonary stenosis to severe pulmonary atresia. Immunostaining showed JBTS17 is localized in the cilia transition zone. Fibroblasts from Hug mutant mice and a JBTS patient with a JBTS17 mutation showed ciliogenesis defects. Significantly, Hug mutant fibroblasts showed loss of not only JBTS17, but also NPHP1 and CEP290 from the cilia transition zone. Hug mutants exhibited reduced ciliation in the cerebellum. This was associated with reduction in cerebellar foliation. Using a fibroblast wound-healing assay, we showed Hug mutant cells cannot establish cell polarity required for directional cell migration. However, stereocilia patterning was grossly normal in the cochlea, indicating planar cell polarity is not markedly affected. Overall, we showed the JBTS pathophysiology is replicated in the Hug mutant mice harboring a Jbts17 mutation. Our findings demonstrate JBTS17 is a cilia transition zone component that acts upstream of other Joubert syndrome associated transition zone proteins NPHP1 and CEP290, indicating its importance in the pathogenesis of Joubert syndrome.
最近的研究确定了一个以前未被描述的基因C5ORF42（JBTS17）是导致Joubert综合征（JBTS）的主要原因，Joubert综合征是一种与小脑异常和其他出生缺陷相关的纤毛病。在此，我们报告了从正向遗传筛选中获得的首个Jbts17突变小鼠模型——“玻璃心”（Hug）。外显子组测序确定Hug是JBTS17（2410089e03rik）小鼠同源基因中的一个S235P错义突变。Hug突变体表现出多种典型的纤毛病出生缺陷，包括骨骼发育不良、多指畸形、颅面异常、肾囊肿和眼部缺陷。一些Hug突变体表现出先天性心脏缺陷，范围从轻度肺动脉狭窄到严重肺动脉闭锁。免疫染色显示JBTS17定位于纤毛过渡区。来自Hug突变小鼠和成纤维细胞以及一名患有JBTS17突变的JBTS患者的成纤维细胞显示出纤毛发生缺陷。值得注意的是，Hug突变体成纤维细胞不仅显示出JBTS17从纤毛过渡区缺失，还显示出NPHP1和CEP290缺失。Hug突变体在小脑中的纤毛形成减少。这与小脑叶形成减少有关。使用成纤维细胞伤口愈合试验，我们发现Hug突变体细胞无法建立定向细胞迁移所需的细胞极性。然而，耳蜗中的静纤毛模式大体正常，表明平面细胞极性没有受到明显影响。总体而言，我们表明在携带Jbts17突变的Hug突变小鼠中复制了JBTS病理生理学。我们的研究结果表明，JBTS17是一种纤毛过渡区成分，作用于其他与Joubert综合征相关的过渡区蛋白NPHP1和CEP290的上游，表明其在Joubert综合征发病机制中的重要性。
