Targeting calcification/ stiffness in glaucoma with Matrix Gla

项目描述 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 这种损伤的重要目标发生在视神经乳头（ONH），RGC轴突在此处离开地球仪 形成视神经尽管不同类型的损伤都可能导致RGC轴突损伤，但这是很好的- 确定了眼内压（IOP）升高和乳头周围区域（ppSC）僵硬是主要的 造成这种退化的原因似乎有理由认为某种分子调控 协调前部和后部受影响的组织对于潜在的治疗将是非常有益的。 青光眼 以前，我们已经确定基质玻璃体（MGP）作为一个最高表达的基因在人类TM。 我们还发现，眼压升高、TGFβ和地塞米松可改变TM中的MGP， 在来自青光眼患者和Mgp-KO小鼠的TM组织中，钙化标记物增加。基因 将钙化诱导剂（BMP 2）转移到大鼠的TM也引起IOP升高。Matrix Gla是一种有效的 软骨细胞和动脉血管平滑肌细胞分泌的矿化抑制剂。MGP KO小鼠在5-6周时由于大量动脉钙化而死亡。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内的分布， 为了在活体动物中对青光眼硬度的潜在调节做出贡献，我们使用了小鼠遗传学。到 为了确定眼内Mgp的空间/时间表达，我们产生了Mgp-Cre敲入（KI）小鼠， 含有与IRES-Cre盒融合的Mgp DNA。该小鼠与R26 R-floxed报告基因（lacZ）的杂交 和td.Tomato）揭示，正如预期的，Mgp在TM区域的高特异性表达，而且， 令人惊讶的是，Mgp在巩膜，特别是ppSC中高度特异性表达。 基于这些发现，我们提出MGP及其抗钙化/抗刚度功能代表了一种 唯一的机制，影响两个基本的青光眼原因，眼压升高和ONH损害的来源。 因此，在本发明中， 我们假设MGP是防止钙化发生的主关键介质， 在目标眼组织的硬度，并作为一个结果，控制的发展和进展， 青光眼 为了发展和证明这一假设，我们建议调查Mgp对脑水肿的反应。 使用新产生的Mgp-Cre-报告基因小鼠（SA#1）进行体内损伤，以克服Mgp 通过创建TM和ppSC特异性条件性敲除（cKO）（SA#2）来评估KO的影响， 对青光眼表型的特异性消融（SA#3 执行本建议所获得的结果将提供机械理解， 开发TM-ppSC联合疗法所需的知识，这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.