Novel dominant-negative FOXJ1 mutation in a family with heterotaxy plus mouse model.
Novel dominant-negative FOXJ1 mutation in a family with heterotaxy plus mouse model.
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DOI：
10.21037/tp-23-27
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发表时间：
2023-08-30
影响因子：
2
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中科院分区：
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原发性纤毛运动障碍（PCD）是一组临床异质性的常染色体或较不常见的X染色体隐性遗传综合征的运动纤毛功能障碍，其特征是新生儿呼吸窘迫，耳鼻喉科疾病，不孕症和内脏逆位。最近，43型PCD（CILD 43，OMIM#618699）是通过Forkhead box J1（FOXJ 1）中鉴定的常染色体显性功能丧失突变建立的。然而，FOXJ 1突变在人类和小鼠中的功能验证尚未完全进行。我们研究了一个三代同堂的先天性心脏病家系，其先证者患有复杂先天性心脏病。我们进行了全外显子组测序，以调查该家族的致病变异，并通过同源重组产生携带人类等效突变的基因敲入小鼠。然后，显微镜分析用于表征模型的表型和纤毛超微结构。通过转录组测序初步探讨该变异体对心脏畸形的影响。FOXJ 1的一个新的杂合缺失变体（c.1129delC/p.Leu377Trpfs*76）被发现在体外发挥显性负效应（DNE）。值得注意的是，纯合子（Foxj1c.1129delT/c.1129delT）和杂合子（Foxj 1 +/c.1129delT）小鼠均发生了内脏逆位、脑积水，并显示气管纤毛结构破坏，而这些异常仅在先前报道的Foxj 1 −/−小鼠中观察到，而不是Foxj 1 +/−小鼠。因此，我们的小鼠模型的更严重的表型和更高的表达率进一步表明了该突变的DNE。同时，一些心肌病相关基因在纯合子Foxj 1基因敲入小鼠心脏中差异表达，表明可能在心脏病理学中起作用。总的来说，我们的研究结果表明，FOXJ 1中的c.1129delC突变被认为是该家族中内脏逆位的原因，并且该突变体显示出比野生型FOXJ 1更强的DNE能力，导致比FOXJ 1等位基因缺失更严重的后果。
Primary ciliary dyskinesia (PCD) is a clinically heterogeneous group of autosomal or, less frequently, X-chromosomal recessive inheritance syndrome of motile cilia dysfunction characterized by neonatal respiratory distress, oto-sino-pulmonary disease, infertility and situs inversus. Recently, type 43 PCD (CILD43, OMIM#618699) was established by autosomal-dominant loss-of-function mutations identified in Forkhead box J1 (FOXJ1). However, the functional validation of FOXJ1 mutations in humans and mice has not been fully performed. Here we studied a three-generation family with heterotaxy and proband with complex congenital heart disease (CHD). We performed whole-exome sequencing to investigate the causative variant of this family and generated gene knock-in mice carrying the human equivalent mutation by homologous recombination. Then, microscopy analysis was used to characterize the phenotype and ciliary ultrastructure of the model. Effects of the variant on heart anomaly were preliminarily explored through transcriptome sequencing. A novel heterozygous deletion variant (c.1129delC/p.Leu377Trpfs*76) of FOXJ1 was discovered that exerts a dominant-negative effect (DNE) in vitro. Notably, both homozygous (Foxj1c.1129delT/c.1129delT) and heterozygous (Foxj1+/c.1129delT) mice developed situs inversus, hydrocephalus and showed a disruption of trachea cilia structure, whereas these abnormalities were only observed in previously reported Foxj1−/−, not Foxj1+/− mice. Thus, a more severe phenotype and higher expressivity of our mouse model further indicated the DNE of this mutation. Meanwhile, several cardiomyopathy-related genes were differentially expressed in the homozygous Foxj1 knock-in mouse hearts, pointing to a probable function in cardiac pathology. Overall, our study results showed that c.1129delC mutation in FOXJ1 was regarded as the cause of situs inversus in this family and this mutant showed a capacity of DNE over wild-type FOXJ1, causing more serious consequences than the allelic deletion of Foxj1.