Roles of Growth Factors on Corneal Morphogenesis

在脊椎动物眼睛发育过程中，角膜、结膜和眼睑的形态发生涉及神经嵴源间充质细胞的迁移和表面外胚层细胞的分化。通过生长因子的双向间充质-上皮相互作用对成人发育和体内平衡过程中的形态发生至关重要。在眼形态发生过程中，tgf - β和FGF- 7在调节神经嵴起源间充质细胞的功能和外胚层细胞的分化中起关键作用。这些功能表现在以下严重的临床表现中：Tgfb2-/-小鼠类似于人类Axenfeld-Reiger异常；角朊蛋白启动子（Kerapr）继发性角膜缘缺陷小鼠；以及FGF-7转基因小鼠的α结晶启动子（alphaACpr）导致角膜表面结膜炎。这些观察结果提出了一些有趣的问题，如：1)。间充质细胞何时转变为内皮细胞？2）. 眼睑间质细胞也是神经嵴起源吗？3）. TGF- β和FGF-7信号在眼睛发育、角膜稳态和伤口愈合中的作用是什么？4)。在KeraprBgn/+转基因小鼠中观察到的表型的分子和细胞机制是什么？为了解决这些问题，我们将创建四环素诱导的转基因小鼠模型，这些小鼠模型在Kerapr的控制下过表达II型tgf - β受体的显性负突变体、活性tgf - β 1和FGF-7，以及在alphaapr的控制下过表达FGF-7。通过这些模型，我们将研究tgf - β信号在角膜发育和稳态过程中的作用，并进一步表征KeraprBgn/+小鼠，以检验过量的高聚糖会干扰眼睑形态发生过程中tgf - β信号的假设。特异性目的1是利用tet-O TbetaRIIdn/+ KeraprrtTA/+和tet-O TGFbeta1/+ KeraprrtTA/+小鼠，阐明tgf - β信号在眼发育、体内平衡和伤口愈合过程中的作用。Specific Aim 2将阐明过表达FGF-7的alphaACprrtTA/+ tet-OFGF7/+和KeraprrtTA/+ tet-OFGF7/+小鼠的眼表上皮分化。特异性目的3将阐明在KeraprBgn/+小鼠发育过程中过量的Biglycan在眼睑形成中的作用。拟议的研究将为更好地理解tgf - β和FGF-7在角膜发育和稳态中的作用提供有用的信息，从而设计更好的角膜疾病治疗方法，例如上皮清创、切口、碱烧伤。

Morphogenesis of cornea, conjunctiva and eyelids during vertebrate eye development involves the migration of mesenchymal cells of neural crest origin and the differentiation of cells of the surface ectoderm. The bi-directional mesenchyme-epithelium interactions via growth factors are essential for morphogenesis during development and homeostasis in adults. TGF-betas and FGF- 7 play pivotal roles in modulating functions of mesenchymal cells of neural crest origin and differentiation of ectoderm cells during ocular morphogenesis. These functions are exemplified by severe clinical manifestations observed as follows: in Tgfb2-/- mice resembling Axenfeld-Reiger's anomaly in human; by biglycan transgenic (KeraprBgn/+) mice of keratocan promoter (Kerapr) exhibiting secondary limbal deficiency; and by FGF-7 transgenic mice of alphaA-crystalline promoter (alphaACpr) resulting in conjunctivalization of corneal surface. These observations raise intriguing questions such as: 1). When do mesenchymal cells commit to becoming endothelial cells? 2). Are eyelid stromal cells also of neural crest origin? 3). What is the role of TGF- beta and FGF-7 signaling in eye development and corneal homeostasis and wound healing? 4). What are the molecular and cellular mechanisms of phenotypes observed in KeraprBgn/+ transgenic mice? To address these questions, we will create tetracycline inducible transgenic mouse models that overexpress the dominant negative mutant of type II TGF-beta receptor, active TGF-beta1 and FGF-7 under the control of Kerapr, and FGF-7 under the control of alphaCApr. With these models we will examine the role of TGF-beta signaling on corneal morphogenesis during development and homeostasis and further characterize the KeraprBgn/+ mice to examine the hypothesis that excess biglycan perturbs TGF-beta signaling during eyelid morphogenesis. Specific Aim 1 is to elucidate roles of TGF-beta signaling on eye morphogenesis during development, homeostasis and wound healing using tet-O TbetaRIIdn/+ KeraprrtTA/+ and tet-O TGFbeta1/+ KeraprrtTA/+ mice. Specific Aim 2 will elucidate ocular surface epithelial differentiation using alphaACprrtTA/+ tet-OFGF7/+ and KeraprrtTA/+ tet-OFGF7/+ mice that overexpress FGF-7. Specific Aim 3 will Elucidate the Role of Excess Biglycan on Eyelid Formation during Development of KeraprBgn/+ mice. The proposed studies will yield useful information for a better understanding of the role of TGF-beta and FGF-7 on corneal development and homeostasis, leading to the design of better treatments for corneal diseases, e.g., epithelial debridement, incision, alkali burn.