Abstract：
Waardenburg Syndrome (WS) is a rare genetic disorder that leads to congenital hearing loss and pigmentation defects. Microphthalmia-associated transcription factor (MITF) is one of its significant pathogenic genes. Despite the comprehensive investigation in animal models, the pathogenic mechanism is still poorly described in humans due to difficulties accessing embryonic tissues. In this work, we used induced pluripotent stem cells derived from a WS patient carrying a heterozygous mutation in the MITF gene c.626A>T (p.His209Leu), and differentiated toward melanocyte lineage, which is the most affected cell type involved in WS. Compared with the wild-type cell line, the MITFmut cell line showed a reduced expression of the characteristic melanocyte-related genes and a lesser proportion of mature, fully pigmented melanosomes. The transcriptome analysis also revealed widespread gene expression changes at the melanocyte stage in the MITFmut cell line. The differentially expressed genes were enriched in melanogenesis and cell proliferation-related pathways. Interestingly, ion transport-related genes also showed a significant difference in MITFmut -induced melanocytes, indicating that the MITF mutant may lead to the dysfunction of potassium channels and transporters produced by intermediate cells in the cochlea, further causing the associated phenotype of deafness. Altogether, our study provides valuable insights into how MITF mutation affects WS patients, which might result in defective melanocyte development and the related phenotype based on the patient-derived iPSC model.
摘要：
Waardenburg综合征（WS）是一种罕见的遗传性疾病，可导致先天性听力损失和色素沉着缺陷。小眼症相关转录因子(MITF)是其重要的致病基因之一。尽管在动物模型中进行了全面的研究，由于难以进入胚胎组织，致病机制在人类中的描述仍然很少。在这项工作中,我们使用了来自WS患者的诱导多能干细胞，该患者在MITF基因c.626A>T中携带杂合突变（p。His209Leu），分化为黑素细胞谱系，这是WS中受影响最大的细胞类型。与野生型细胞系相比，MITFmut细胞系显示特征性黑素细胞相关基因的表达降低，成熟细胞的比例较低，完全色素沉着的黑色素体。转录组分析还揭示了MITFmut细胞系中黑素细胞阶段的广泛基因表达变化。差异表达的基因富集在黑色素生成和细胞增殖相关途径中。有趣的是,离子转运相关基因在MITFmut诱导的黑素细胞中也显示出显著差异，表明MITF突变体可能导致耳蜗中间细胞产生的钾通道和转运蛋白的功能障碍，进一步引起耳聋的相关表型。总之,我们的研究为MITF突变如何影响WS患者提供了有价值的见解，根据患者来源的iPSC模型，这可能导致黑素细胞发育缺陷和相关表型。
