Mechanisms of development of curved refractive surfaces

角膜的异常曲率与包括近视在内的多种视觉缺陷有关， 远视、圆锥角膜和散光。然而，产生这种现象的发展机制 适当的角膜曲率还没有被很好地理解。该方案将果蝇角膜透镜用作 一个简单的模型系统来调查曲率的发展，并将测试它是否有共同的 哺乳动物角膜的分子和发育机制。该项目基于数据 这表明保守的Blimp-1转录因子对于果蝇的外曲率是必需的 角膜透镜，并且它作用于外周的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透镜物质的细胞。类似功能的可能性 对于小鼠Blimp 1/Prdm 1，通过其在角膜缘上皮细胞中的富集来表明， 成人角膜第一个目标是研究控制果蝇角膜透镜的转录网络 发展在缺乏Blimp-1的情况下，C/EBP同源物Slow border cells（Slbo）高度表达。 上调和Slbo过表达，如Blimp-1的缺失，导致外部平坦的角膜晶状体。的 将通过使两种基因失活来检验SLBO阻遏是Blimp-1的主要功能的假设 同步这一目标还将确定Blimp-1下游的其他关键转录因子， 测试眼内Blimp-1的瞬时经尿道调节的表达是否对颞叶 控制分化。第二个目标将确定外周色素细胞如何有助于 角膜透镜曲率。将研究两种可能性：色素细胞分泌蛋白质成分 其定位于周边角膜透镜并赋予其不同于中心区域的结构特性， 并且通过角膜透镜与色素细胞的连接而施加在角膜透镜上的力控制了 曲率第三个目标是探索昆虫和哺乳动物角膜之间可能的保护 结构. CG 43333是一个在果蝇视网膜中被Blimp-1抑制的基因， Blimp-1突变体的异常角膜透镜表型，与转化生长因子β- 诱导蛋白，在人类角膜营养不良的突变的常见目标。疾病突变的影响 将检查CG 43333的累积和定位，以确定它们是否再现特征 角膜营养不良人类角膜上皮细胞和角膜类器官将用于确定是否 人BLIMP 1在角膜中具有与果蝇Blimp-1共同的靶基因。最后 将检查Blimp 1在小鼠角膜中的发育表达模式，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被赋予 屈光结构主要由细胞外基质组成，并将建立果蝇角膜 透镜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.