Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada.
Department of Ophthalmology, University of Alberta, Edmonton, AB T6G 2H7, Canada.
Genes (Basel). 2021 Jan 26;12(2):170. doi: 10.3390/genes12020170.
Precise spatiotemporal expression of the -- cascade in the lateral plate mesoderm establishes the left-right axis, which provides vital cues for correct organ formation and function. Mutations of one cascade constituent and, separately, the Forkhead transcription factor independently cause a multi-system disorder known as Axenfeld-Rieger syndrome (ARS). Since cardiac involvement is an established ARS phenotype and because disrupted left-right patterning can cause congenital heart defects, we investigated in zebrafish whether contributes to organ laterality or situs. We demonstrate that CRISPR/Cas9-generated and mutants exhibit abnormal cardiac looping and that the prevalence of cardiac situs defects is increased in ; homozygotes. Similarly, double homozygotes exhibit isomerism of the liver and pancreas, which are key features of abnormal gut situs. Placement of the asymmetric visceral organs relative to the midline was also perturbed by mRNA overexpression of and . In addition, an analysis of the left-right patterning components, identified in the lateral plate mesoderm of mutants, reduced or abolished the expression of the antagonist . Together, these data reveal a novel contribution from to left-right patterning, demonstrating that this role is sensitive to gene dosage, and provide a plausible mechanism for the incidence of congenital heart defects in Axenfeld-Rieger syndrome patients.
精确的时空表达级联在侧板中胚层建立了左右轴，为正确的器官形成和功能提供了重要线索。级联成分之一和叉头转录因子的突变，分别独立导致一种多系统疾病，称为 Axenfeld-Rieger 综合征 (ARS)。由于心脏受累是 ARS 的一种已确立表型，并且左右模式的破坏会导致先天性心脏缺陷，我们在斑马鱼中研究了是否级联参与器官偏侧性或 situs。我们证明，CRISPR/Cas9 产生的和突变体表现出异常的心脏环化，并且在中，心脏 situs 缺陷的患病率增加。同样，双纯合子也表现出肝脏和胰腺的同型性，这是异常肠道 situs 的关键特征。不对称内脏器官相对于中线的位置也被和的 mRNA 过表达所扰乱。此外，对侧板中胚层突变体中鉴定的左右模式成分的分析，减少或消除了的拮抗剂的表达。总之，这些数据揭示了级联对左右模式的新贡献，表明该作用对基因剂量敏感，并为 Axenfeld-Rieger 综合征患者中先天性心脏缺陷的发生率提供了合理的机制。
