Targeting calcification/ stiffness in glaucoma with Matrix Gla

项目说明 在青光眼的发展过程中，视网膜神经节细胞(RGC)及其轴突退化。一个 这种损伤的重要靶点发生在视神经头(ONH)，在那里RGC轴突离开地球 形成视神经。虽然RGC轴突损伤可以由不同类型的侮辱引起，但它很好- 确定高眼压(IOP)和乳头周围区僵硬(PPSC)是主要的 造成这种退化的因素。认为某种分子调控似乎是合乎逻辑的 协调受影响的前后部组织将对潜在的治疗有很大的好处 青光眼。 此前，我们已发现Matrix GLA(MGP)是人类TM中表达最高的基因之一。 我们还发现，高眼压、转化生长因子β和地塞米松改变了TM中的MGP，并且 在青光眼患者和MGP-KO小鼠的TM组织中，钙化标志物增加。基因 将钙化诱导剂(BMP2)转移到大鼠的TM也引起了高眼压。Matrix GLA是一款强大的 软骨细胞和动脉血管平滑肌细胞分泌的矿化抑制物。MGP KO小鼠因动脉大量钙化而在5-6周内死亡。动脉钙化导致动脉僵硬 和更高的收缩压。为了研究MGP在眼内的丰度及其在眼球中的分布 在活体动物中对青光眼僵硬的潜在调节的贡献，我们使用了小鼠遗传学。至 为了确定MGP在眼睛中的空间/时间表达，我们产生了MGP-Cre敲入(KI)小鼠， 含有融合在IRES-Cre-盒上的MGP DNA。此鼠标与R26R-Floated Report(Lacz)的交叉 和td番茄)揭示了Mgp在TM区域的高特异性表达，但也显示了MGP在TM区域的高特异性表达 令人惊讶的是，Mgp在巩膜特别是PPSC中高度和特异地表达。 基于这些发现，我们认为MGP及其抗钙化/抗僵硬功能代表了一种 影响青光眼两个基本原因的唯一机制，即高眼压和ONH损害。 因此， 我们假设MGP是一个防止钙化发生的主密钥介体。 在目标眼组织中的僵硬，并因此控制着 青光眼。 为了发展和证明这一假说，我们建议研究MGP对青光眼的反应。 使用新产生的MGP-CRE报告小鼠(SA#1)在体内侮辱，以推翻MGP的早期死亡 通过创建TM和PPSC特定的条件淘汰赛(CKO)(SA#2)并评估 青光眼表型的特异性消融(SA#3 通过执行本提案而取得的结果将提供机械性的理解和 开发TM-PPSC联合疗法所需的知识可能会导致一种全新的 青光眼的治疗。

PROJECT DESCRIPTION During the progression of glaucoma, the retinal ganglion cells (RGC) and their axons degenerate. An important target to this damage occurs in the optic nerve head (ONH), where the RGC axons leave the globe to form the optic nerve. Although RGC axonal damage can be caused by different type of insults, it is well- established that elevated intraocular pressure (IOP) and stiffness in the peripapillary region (ppSC) are major contributors to this degeneration. It would seem logical to think that some kind of molecular regulation coordinating the anterior and posterior affected tissues would be of great benefit for a potential treatment of glaucoma. Previously, we had identified Matrix Gla (MGP) as one of most highly expressed genes in the human TM. We had also found that MGP was altered in the TM by elevated IOP, TGFβ and dexamethasone, and that calcification markers were increased in TM tissues from glaucoma patients and Mgp-KO mice. The gene transfer of a calcification inducer (BMP2) to the rat’s TM also elicited elevated IOP. Matrix Gla is a potent mineralization inhibitor secreted by cartilage chondrocytes and arteries’ vascular smooth muscle cells. Mgp KO mice die at 5-6 weeks due to massive arterial calcification. Arterial calcification results in arterial stiffness and higher systolic blood pressure. In order to investigate the abundance of Mgp in the eye and its contribution to a potential regulation of stiffness in glaucoma in a living animal, we used mouse genetics. To determine the Mgp spatial/ temporal expression in the eye, we generated an Mgp-Cre Knock-in (KI) mouse, containing Mgp DNA fused to an IRES-Cre-cassette. Crosses of this mouse with R26R-floxed reporters (lacZ and td.Tomato) revealed, as expected, Mgp’s high specific expression in the TM region, but also, and surprisingly, Mgp was highly and specifically expressed in the sclera, in particularly the ppSC. Based on these findings, we propose that MGP and its anti-calcification/ anti-stiffness function represents a sole mechanism that affects the source of two basic glaucomatous causes, elevated IOP and ONH damage. Thus, we hypothesize that MGP is a master key-mediator that prevents the occurrence of calcification/ stiffness in the targeted eye tissues, and as a consequence, controls the development and progression of glaucoma. To develop and prove this hypothesis, we propose to investigate the response of Mgp to glaucomatous insults in vivo using the newly generated Mgp-Cre-reporter mice (SA#1), to override the early death of the Mgp KO by creating TM and ppSC specific conditional Knock-outs (cKOs) (SA#2) and to evaluate the impact of the specific ablations on glaucoma phenotypes (SA#3 Results to be obtained with the execution of this proposal will provide the mechanistic understanding and the knowledge needed to develop a combined TM-ppSC therapy which could potentially lead to a totally new treatment of glaucoma.