Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan.
Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan; Institute of Brain Science, School of Medicine, National Yang Ming Chiao Tung University, Taipei, 11221, Taiwan.
Differentiation. 2024 May-Jun;137:100781. doi: 10.1016/j.diff.2024.100781. Epub 2024 Apr 10.
Pax6 is a critical transcription factor involved in the development of the central nervous system. However, in humans, mutations in Pax6 predominantly result in iris deficiency rather than neurological phenotypes. This may be attributed to the distinct functions of Pax6 isoforms, Pax6a and Pax6b. In this study, we investigated the spatial and temporal expression patterns of Pax6 isoforms during different stages of mouse eye development. We observed a strong correlation between Pax6a expression and the neuroretina gene Sox2, while Pax6b showed a high correlation with iris-component genes, including the mesenchymal gene Foxc1. During early patterning from E10.5, Pax6b was expressed in the hinge of the optic cup and neighboring mesenchymal cells, whereas Pax6a was absent in these regions. At E14.5, both Pax6a and Pax6b were expressed in the future iris and ciliary body, coinciding with the integration of mesenchymal cells and Mitf-positive cells in the outer region. From E18.5, Pax6 isoforms exhibited distinct expression patterns as lineage genes became more restricted. To further validate these findings, we utilized ESC-derived eye organoids, which recapitulated the temporal and spatial expression patterns of lineage genes and Pax6 isoforms. Additionally, we found that the spatial expression patterns of Foxc1 and Mitf were impaired in Pax6b-mutant ESC-derived eye organoids. This in vitro eye organoids model suggested the involvement of Pax6b-positive local mesodermal cells in iris development. These results provide valuable insights into the regulatory roles of Pax6 isoforms during iris and neuroretina development and highlight the potential of ESC-derived eye organoids as a tool for studying normal and pathological eye development.
Pax6 是一种关键的转录因子，参与中枢神经系统的发育。然而，在人类中，Pax6 的突变主要导致虹膜缺失，而不是神经表型。这可能归因于 Pax6 同工型 Pax6a 和 Pax6b 的不同功能。在这项研究中，我们研究了 Pax6 同工型在不同阶段的小鼠眼睛发育过程中的时空表达模式。我们观察到 Pax6a 表达与神经视网膜基因 Sox2 之间存在很强的相关性，而 Pax6b 与虹膜成分基因（包括间充质基因 Foxc1）表现出高度相关性。在早期形态发生从 E10.5 开始，Pax6b 在视杯的铰链和邻近的间充质细胞中表达，而 Pax6a 在这些区域不存在。在 E14.5，Pax6a 和 Pax6b 都在未来的虹膜和睫状体中表达，与间质细胞和 Mitf 阳性细胞在外区的整合相吻合。从 E18.5 开始，随着谱系基因变得更加受限，Pax6 同工型表现出不同的表达模式。为了进一步验证这些发现，我们利用 ESC 衍生的眼睛类器官，这些类器官重现了谱系基因和 Pax6 同工型的时空表达模式。此外，我们发现 Foxc1 和 Mitf 的空间表达模式在 Pax6b 突变的 ESC 衍生的眼睛类器官中受损。这个体外眼睛类器官模型表明 Pax6b 阳性局部中胚层细胞参与了虹膜发育。这些结果提供了关于 Pax6 同工型在虹膜和神经视网膜发育中的调节作用的有价值的见解，并强调了 ESC 衍生的眼睛类器官作为研究正常和病理性眼睛发育的工具的潜力。
