The role of LTBP2 in glaucoma

摘要： LTBP2基因自发突变的青光眼动物模型已经建立。这 基因与包括人类原发性先天性青光眼在内的多种青光眼表型有关 (PCG)以及某些形式的成人型开角型青光眼。作为已知的唯一的大型动物同源物 这种模型在人类遗传性青光眼中具有相当大的转化性研究潜力。后方 节段性病理学已经被广泛地描述并紧密概括了人类的特征 青光眼视神经病变。然而，LTBP2在眼睛中扮演的角色仍不清楚，而且 导致眼压升高的确切细胞和分子机制 在这种形式的青光眼仍然没有解决。这项提议目标是确定和本地化，如 治疗干预的潜在靶点，关键的病理生物学机制，有助于早期 在这个模型中，眼压开始升高和进行性升高。除了对LTBP2感到不安外，S承认在 微原纤维组装，增强转化生长因子β信号，促进细胞外基质(ECM)积聚 在小梁内网(TM)被认为是眼压升高的一种机制 “微纤维病症”。然而，在我们的动物模型中的初步研究还没有确定是否显著 房水中转化生长因子β浓度的升高代表了眼压升高的原因或结果。我们的中央 假设LTBP2既是外流通路发展和重塑的重要调节因子。 围产期和TM细胞和ECM生物学的调节器以及整个生命过程中的促纤维化途径， 超越发展的延伸。我们将追求两个具体目标：目标1：确定缺席的影响 或减少LTBP2的表达对近端和远端房水流出通路的发展，我们将测试 假设LTBP2在外流通路的发展和重塑中发挥重要作用 活体和原位相结合的方法研究远端流出的形态和超微结构 野生型近端流出通路(TM和跟骨旁组织)及其ECM成分 LTBP2+/-和LTBP2-/-眼。目的2：确定LTBP2缺失或减少的病理效应 在TM细胞(TMC)生物学上的表达，我们将使用来自野生型、LTBP2+/-和LTBP2-/-的TMC培养物 眼睛。在目标2中，我们将测试以下假设：LTBP2表达减少将a)对TMC产生负面影响 B)增强转化生长因子β对肌动蛋白细胞骨架的病理作用 促进细胞外基质纤维化。这些目标的成功完成将产生关于该建筑群的新知识 LTBP2在房水流出通道的生理和病理中的作用，为 推进我们设计和测试青光眼创新治疗方法的总体目标 翻译模型。

Summary: A unique animal model of glaucoma with spontaneously arising mutation in LTBP2 has been established. This gene is implicated in heterogeneous glaucoma phenotypes, including human primary congenital glaucoma (PCG) as well as some forms of adult-onset open angle glaucoma. As the only known large animal homolog of inherited glaucoma in humans, this model has considerable potential for translational research. Posterior segment pathology has been extensively characterized and closely recapitulates features of human glaucomatous optic neuropathy. However, the role played by LTBP2 in the eye remains unknown and the precise cellular and molecular mechanisms responsible for the underlying elevated intraocular pressure (IOP) in this form of glaucoma remain unresolved. The objective of this proposal is to identify and localize, as potential targets for therapeutic intervention, key pathobiological mechanisms that contribute to both early onset and progressive IOP elevation in this model. In addition to perturbing LTBP2’s acknowledged role in microfibril assembly, enhanced TGF beta signaling, contributing to extracellular matrix (ECM) accumulation within the trabecular meshwork (TM) has been proposed as a mechanism for IOP elevation in this “microfibrillopathy”. However, preliminary studies in our animal model have not established whether significant increase in aqueous humor TGF beta concentrations represent a cause or effect of IOP elevation. Our central hypothesis is that LTBP2 is both an important regulator of outflow pathway development and remodeling in the perinatal period and a regulator of TM cell and ECM biology and pro-fibrotic pathways throughout life, extending beyond development. We will pursue two specific Aims: Aim 1: To determine the effects of absent or reduced LTBP2 expression on development of proximal and distal aqueous outflow pathways, we will test the hypothesis that LTBP2 plays an important role in outflow pathway development and remodeling using a combination of in vivo and in situ approaches to examine distal outflow morphology and ultrastructure of the proximal outflow pathway (TM and juxtacanalicular tissue) and ECM components of these pathways in wildtype and LTBP2+/- and LTBP2-/- eyes. Aim 2: To determine the pathological effects of absent or reduced LTBP2 expression on TM cell (TMC) biology, we will use TMC cultures derived from wildtype, LTBP2+/- and LTBP2-/- eyes. In Aim 2, we will test the hypotheses that reduced LTBP2 expression will a) negatively impact TMC attachment and proliferation in vitro and b) enhance the pathologic effects of TGFβ on actin cytoskeleton and promotion of ECM fibrosis. Successful completion of these Aims will generate new knowledge on the complex role of LTBP2 in physiology and pathology of the aqueous outflow pathways, providing a critical foundation to advance our overall goal of designing and testing innovative therapeutic approaches to glaucoma in our unique translational model.