Mechanisms of development of curved refractive surfaces

角膜曲率异常与多种视觉缺陷有关，包括近视、 远视、圆锥角膜和散光。然而，产生的发育机制 适当的角膜曲率尚不清楚。该提案将使用果蝇角膜晶状体作为 一个简单的模型系统来研究曲率的发展，并测试它是否有共同点 哺乳动物角膜的分子和发育机制。该项目基于数据 表明保守的 Blimp-1 转录因子对于果蝇的外部弯曲至关重要 角膜晶状体，并且它作用于外周二级和三级色素细胞，而不是中央色素细胞 分泌大量细胞外角膜晶状体物质的细胞。类似函数的可能性 对于小鼠 Blimp1/Prdm1 来说，其在角膜缘周围的角膜缘上皮细胞中富集表明 成人角膜。第一个目标是研究控制果蝇角膜晶状体的转录网络 发展。在缺乏 Blimp-1 的情况下，C/EBP 同源物慢边界细胞 (Slbo) 高度 上调和 Slbo 过度表达（如 Blimp-1 缺失）会导致角膜晶状体外部平坦。的 假设 slbo 抑制是 Blimp-1 的主要功能，将通过灭活这两个基因来测试 同时。这一目标还将确定 Blimp-1 下游的其他关键转录因子，并将 测试眼睛中 Blimp-1 的瞬时激素调节表达是否对颞叶神经重要 分化的控制。第二个目标将确定外周色素细胞如何促进 角膜晶状体曲率。将研究两种可能性：色素细胞分泌蛋白质成分 定位于周边角膜晶状体并赋予其与中心区域不同的结构特性， 通过附着在色素细胞上施加在角膜晶状体上的力控制着角膜晶状体的模式 曲率。第三个目标将探索昆虫和哺乳动物角膜之间可能的保护 结构。 CG43333，一种在果蝇视网膜中被 Blimp-1 抑制的基因，有助于 Blimp-1突变体的异常角膜晶状体表型与转化生长因子β同源 诱导蛋白，人类角膜营养不良的常见突变目标。疾病突变的影响 将检查 CG43333 的积累和定位以确定它们是否再现特征 角膜营养不良。人角膜上皮细胞和角膜类器官将用于确定是否 人类 BLIMP1 与果蝇 Blimp-1 在角膜中具有共同的靶基因。最后， 将检查小鼠角膜中 Blimp1 的发育表达模式，以确定其是否 与角膜曲率的作用一致。这些实验将阐明曲率是如何赋予的 屈光结构主要由细胞外基质组成，并将建立果蝇角膜 晶状体作为了解角膜发育和疾病的模型。

Abnormal curvature of the cornea is associated with multiple visual defects including myopia, hyperopia, keratoconus and astigmatism. However, the developmental mechanisms that generate appropriate corneal curvature are not well understood. This proposal will use the Drosophila corneal lens as a simple model system to investigate the development of curvature, and will test whether it shares common molecular and developmental mechanisms with the mammalian cornea. The project is based on data showing that the conserved Blimp-1 transcription factor is essential for external curvature of the Drosophila corneal lens, and that it acts in the peripheral secondary and tertiary pigment cells rather than in the central cells that secrete the bulk of the extracellular corneal lens material. The possibility of an analogous function for mouse Blimp1/Prdm1 is suggested by its enrichment in the limbal epithelial cells at the periphery of the adult cornea. The first aim will investigate the transcriptional network that controls Drosophila corneal lens development. In the absence of Blimp-1, the C/EBP homologue Slow border cells (Slbo) is highly upregulated, and Slbo overexpression, like loss of Blimp-1, results in externally flat corneal lenses. The hypothesis that slbo repression is a major function of Blimp-1 will be tested by inactivating both genes simultaneously. This aim will also identify other critical transcription factors downstream of Blimp-1, and will test whether transient hormonally regulated expression of Blimp-1 in the eye is important for the temporal control of differentiation. The second aim will determine how the peripheral pigment cells contribute to corneal lens curvature. Two possibilities will be investigated: that pigment cells secrete protein components that localize to the peripheral corneal lens and give it structural properties distinct from the central region, and that force exerted on the corneal lens through its attachments to pigment cells controls the pattern of curvature. The third aim will explore possible conservation between insect and mammalian corneal structures. CG43333, a gene that is repressed by Blimp-1 in the Drosophila retina and contributes to the abnormal corneal lens phenotype of Blimp-1 mutants, is homologous to Transforming growth factor beta- induced protein, a frequent target of mutation in human corneal dystrophies. The effect of disease mutations on CG43333 accumulation and localization will be examined to determine whether they reproduce features of corneal dystrophy. Human corneal epithelial cells and corneal organoids will be used to establish whether human BLIMP1 has target genes in common with Drosophila Blimp-1 in the cornea. Finally, the developmental expression pattern of Blimp1 in the mouse cornea will be examined to determine whether it is consistent with a role in corneal curvature. These experiments will elucidate how curvature is imparted to refractive structures composed primarily of extracellular matrix, and will establish the Drosophila corneal lens as a model to understand corneal development and disease.