Defining the cellular mechanisms of craniosynostosis in a human induced pluripotent stem cell model of craniofrontonasal syndrome

描述（由申请人提供）：颅额鼻综合征（CFNS）是一种X连锁神经嵴病，其特征为骨骼和神经异常。CFNS是由EFNB 1突变引起的，EFNB 1编码EPHRIN-B1，一种跨膜蛋白和信号分子Eph/ephrin家族的成员。与许多X连锁疾病不同，EFNB 1缺失的杂合子女性比半合子男性受到更严重的影响。这种独特的遗传模式是由于在杂合子女性中随机X失活后EFNB 1表达的嵌合体。在Efnb 1 +/-小鼠中，嵌合体导致肝配蛋白-B1表达和非表达细胞之间的活跃细胞分选，导致肝配蛋白-B1表达边界被破坏，但这种细胞分选发生的机制仍不完全清楚。此外，细胞分选尚未在CFNS的人类模型中得到证实，因此尚不清楚细胞分选是否对疾病病理生理学有显著贡献。 CFNS的一个重要临床表现是冠状面颅缝早闭，或颅骨的额骨和顶骨之间的缝过早融合。然而，在Efnb 1 +/-小鼠模型中未观察到这种表型，这对理解其病因构成了障碍。因此，需要一个人类系统来了解CFNS中冠状面颅缝早闭的细胞机制。人类诱导多能干细胞（hiPSC）在人类疾病的研究中具有巨大的潜力，因为它们允许患者特异性细胞分化为疾病相关的细胞类型，这些细胞类型通常难以或不可能直接获得。hiPSC已用于对多种发育疾病建模，但它们尚未用于对先天性颅面异常建模。我们已经开发了一种新的CFNS hiPSC模型，以研究该疾病的潜在细胞和分子病因，并证明hiPSC衍生的神经上皮细胞经历Eph/肝配蛋白介导的细胞分选。我建议使用我们的hiPSC模型CFNS，以确定的途径，有助于Eph/肝配蛋白介导的细胞分选，以及研究细胞分选有助于颅缝早闭CFNS。

DESCRIPTION (provided by applicant): Craniofrontonasal syndrome (CFNS) is an X-linked neurocristopathy characterized by skeletal and neurological anomalies. CFNS is caused by mutations in EFNB1, which encodes EPHRIN-B1, a transmembrane protein and member of the Eph/ephrin family of signaling molecules. Unlike many X-linked conditions, females heterozygous for loss of EFNB1 are more severely affected than hemizygous males. This unique inheritance pattern is due to mosaicism for EFNB1 expression after random X inactivation in heterozygous females. In Efnb1+/- mice, mosaicism leads to active cell sorting between ephrin-B1 expressing and non-expressing cells, resulting in disrupted ephrin-B1 expression boundaries, but the mechanism by which this cell sorting occurs remains incompletely understood. Moreover, cell sorting has not been demonstrated in a human model for CFNS, and it is therefore unknown whether or not cell sorting contributes significantly to disease pathophysiology. One clinically important manifestation of CFNS is coronal craniosynostosis, or premature fusion of the suture between the frontal and parietal bones of the skull. This phenotype is not observed in the Efnb1+/- mouse model, however, presenting an obstacle to understanding its etiology. A human system is therefore needed to understand cellular mechanisms underlying coronal craniosynostosis in CFNS. Human induced pluripotent stem cells (hiPSCs) hold great potential for the study of human disease, as they allow differentiation of patient-specific cells into disease-relevant cell types, which are often difficut or impossible to obtain directly. hiPSCs have been used to model a wide variety of developmental diseases, but they have not been used to model congenital craniofacial anomalies. We have developed a novel hiPSC model for CFNS to study the underlying cellular and molecular etiologies of the disorder and have demonstrated that hiPSC-derived neuroepithelial cells undergo Eph/ephrin-mediated cell sorting. I propose to use our hiPSC model of CFNS to determine the pathways that contribute to Eph/ephrin-mediated cell sorting as well as to study how cell sorting contributes to craniosynostosis in CFNS.