Eph-ephrin signaling in the lens

项目摘要 根据世界卫生组织的说法，与年龄相关的晶状体病变是导致视力的主要原因 世界上最大的损害。白内障，定义为眼晶状体中的任何混浊，仍然是导致 世界上的盲人。老花眼是由于调焦过程中晶状体改变形状的能力降低所致 (住宿)，以此类推，需要老花镜。未解决的老花眼是最主要的 全球范围内视力受损的原因。几十年的研究集中在先天性晶状体的病理上，因此， 人们对促进终身晶状体的潜在细胞和分子机制知之甚少。 动态平衡。最近的研究报道，EphA2受体或ePhin-A5配体的突变是 与人类和小鼠的变异性先天性和年龄相关性白内障有关，这些双向的 信号分子是调节晶状体细胞组织和稳定性的关键成分。 我们的小鼠模型显示，EphA2的缺失会导致与人类相似的年龄相关性皮质性白内障 有EphA2功能障碍的患者。我们将评估我们的小鼠的白内障进展情况，以研究细胞 以及在皮质性白内障形成过程中发生的分子变化。我们假设EphA2的丢失会导致 在细胞骨架结构的变化或细胞与细胞的黏附导致光学 晶状体皮质不连续。 我们的新数据显示，晶状体既利用了规范配体介导的EphA2双向信号，也利用了EphA2双向信号 非正则配体非依赖的EphA2信号通路。我们假设经典的EphA2信号 赤道上皮细胞需要EphA2激活，而纤维细胞则需要非规范的EphA2激活 分化和成熟，这种受体活性的分离可以解释为什么 EphA2突变引起的人类先天性和老年性白内障。我们将对激活进行评估 EphA2在空间和时间上的模式，并决定已知的下游通路在 不同的晶状体细胞群。我们将EphA2激动剂和拮抗剂多肽应用于原代培养小鼠 晶状体上皮细胞产生迷你晶状体作为晶状体发育的体外模型。 晶状体中心或核的大小和硬度的增加被认为是导致非晶状体病变的关键因素 不仅与年龄相关的整体晶状体僵硬和老花眼增加，而且营养不良和废物运输也很差 导致与年龄相关的核性白内障。我们新的初步数据显示，失去EphA2会导致更软， 晶状体核较小。我们假设Eph-ephin信号是正常细胞-细胞黏附所必需的，并且 驱动核纤维细胞膜重组和致密的细胞骨架重排。此数据 将提供一个更好的理解协调信号机制，以维持动态平衡在 正常老化和晶状体透明度和生物力学性质的变化，这可能导致 开发新的非手术方法以延缓或预防年龄相关的晶状体病变。

Project Summary According to the World Health Organization, age-related lens pathologies are the leading cause of visual impairment in the world. Cataracts, defined as any opacity in the eye lens, remain the leading cause of blindness in the world. Presbyopia is caused by a reduction in the lens’ ability to change shape during focusing (accommodation), and, by extension, the need for reading glasses. Unaddressed presbyopia is the leading cause of visual impairment globally. Decades of study have focused on congenital lens pathologies, and thus, very little is known about the underlying cellular and molecular mechanisms that facilitate lifelong lens homeostasis. Recent studies have reported that mutations of the EphA2 receptor or the ephrin-A5 ligand are associated with variable congenital and age-related cataracts in humans and mice, and these bidirectional signaling molecules are key components for regulating lens cell organization and stability. Our mouse models reveal that loss of EphA2 leads to age-related cortical cataracts similar to human patients with EphA2 dysfunction. We will evaluate cataract progression in our mouse line to study the cellular and molecular changes that occur during cortical cataract formation. We hypothesize that loss of EphA2 results in changes in cytoskeletal structures or cell-cell adhesion of peripheral fiber cells leading to optical discontinuities in the lens cortex. Our new data show that the lens utilizes both canonical ligand-mediated EphA2 bidirectional signaling and non-canonical ligand-independent EphA2 signaling pathways. We hypothesize that canonical EphA2 signaling is required in equatorial epithelial cells while non-canonical EphA2 activation is required for fiber cell differentiation and maturation and that this segregation of receptor activity may explain the large variety of human congenital and age-related cataracts caused by EphA2 mutations. We will evaluate the activation pattern of EphA2 spatially and temporally and determine the activity of known downstream pathways in different lens cell populations. We will apply EphA2 agonist and antagonist peptides to primary culture mouse lens epithelial cells to generate mini lenses as an in vitro model for lens development. Increased size and stiffness of the lens center or nucleus has been hypothesized to be a key factor for not only age-related increases in overall lens stiffness and presbyopia, but also poor nutrient and waste transport leading to age-related nuclear cataracts. Our new preliminary data shows that loss of EphA2 leads to softer, smaller lens nuclei. We hypothesize that Eph-ephrin signaling is required for normal cell-cell adhesion and cytoskeleton rearrangement that drives nuclear fiber cell membrane re-organization and compaction. This data will provide a better understanding of coordinated signaling mechanisms for maintaining homeostasis during normal aging and in lenses with changes in transparency and biomechanical properties, which may lead to the development of new non-surgical approaches to delay or prevent age-related lens pathologies.