Ocular Dysgenesis in Agrin Transgenic Mice

描述(申请人提供)：过度表达蛋白多糖凝集素的转基因小鼠在眼睛发育方面存在严重缺陷。我们的假设是，这种功能获得性集聚蛋白突变通过扰乱发育中眼睛细胞外基质(ECM)的正常功能而扰乱眼睛发育。表型也与菌株有关，只出现在C57BL/6的遗传背景中，但在该菌株中完全外显。因此，我们还假设C57BL/6小鼠为这种表型提供了致敏的背景，并且识别这种敏感性的基因将与相关的人类状况相关。Agrin转基因小鼠的表型范围从完全无眼症到由于晶状体未能与角膜分离而导致的角膜混浊。常见的表型包括严重的缺损，晶状体形成失败，以及色素纤维血管组织渗入眼睛。转基因蛋白定位于受影响的相同结构。根据转基因蛋白的定位和第二个独立的转基因创始人眼睛缺陷的增加(尽管只有30%的初始外显率)，我们得出结论，表型是眼睛中存在转基因蛋白的直接结果。然而，还没有正式排除这种表型是由非特异性胎儿应激反应或转基因插入造成的突变引起的可能性。这项提议的第一个具体目标是使用遗传和分子方法相结合的方法来确定这一点。表型依赖于菌株，C57BL/6小鼠容易发生自发性眼部缺陷，发生率约为5%。转agrin基因的表型类似于自发性缺陷的严重极端。C57BL/6为研究眼睛发育提供了一个敏感的背景，而agrin转基因结构加剧了这种敏感性。这项建议的第二个具体目标是在经典的遗传图谱实验中使用agrin转基因小鼠来识别C57BL/6背景中使该菌株易患眼睛发育不良的基因座。将集聚蛋白过度表达的特征作为探索ECM作用的工具，将开辟许多新的研究途径。此外，识别这些转基因小鼠眼睛缺陷的易感基因将对研究信号分子、环境因素和蛋白质效应在小鼠和人类中的联系大有裨益。

DESCRIPTION (provided by applicant): Transgenic mice that over express the proteoglycan agrin have severe defects in ocular development. It is our hypothesis that this gain-of-function agrin mutation is perturbing eye development by disrupting the normal functions of the extracellular matrix (ECM) in the developing eye. The phenotype is also strain dependent, occurring only in a C57BL/6 genetic background, but with complete penetrance in that strain. Therefore, we also hypothesize that C57BL/6 mice provide a sensitized background for this phenotype, and that identifying the genes underlying this sensitivity will be relevant to related human conditions. The phenotype of the agrin-transgenic mice ranges from complete anophthalmia to corneal opacities caused by a failure of the lens to separate from the cornea. Frequently observed phenotypes include severe colobomas, a failure of lens to form, and an infiltration of pigmented fibrovascular tissue into the eye. The transgenic protein localizes to same structures that are affected. Based upon the localization of the transgenic protein and an increase in eye defects in a second, independent transgenic founder (though only at thirty percent initial penetrance) we conclude that the phenotype is a direct result of the presence of the transgenic protein in the eye. However, the possibilities that the phenotype is caused by a non-specific fetal stress response or by a mutation created by the transgene insertion have not been formally ruled out. The first specific aim of this proposal is to make this determination using a combination of genetic and molecular approaches. The phenotype is strain dependent and C57BL/6 mice are prone to spontaneous ocular defects at a rate of approximately five percent. The agrin-transgenic phenotypes resemble the severe extremes of the spontaneous defects. C57BL/6 provides a sensitized background for studying eye development, and the agrin-transgenic construct exacerbates this sensitivity. The second specific aim of this proposal is to use the agrin-transgenic mice in a classic genetic mapping experiment to identify the loci in the C57BL/6 background that predispose this strain to ocular dysgenesis. The haracterization of agrin overexpression as a tool for exploring the role of the ECM will open many new avenues of research. In addition, the identification of genes predisposing these transgenic mice to eye defects will be of great benefit to studies linking signaling molecules, environmental factors and protein effectors in both mice and humans.