Aberrant RPE mTORC1 signaling in dysregulation of choroid homeostasis

该项目的总体目标是描绘与脑功能障碍相关的细胞和分子机制。 视网膜色素上皮（RPE）至脉络膜毛细血管（CC）变性。脉络膜萎缩是一种早期 老年性黄斑变性（AMD）是老年人致盲的主要原因， 人RPE产生许多营养因子，其支持脉络膜的结构完整性。 脉管系统衰老和与年龄相关的退化可以干扰细胞之间的功能相互作用， RPE和CC。潜在的疾病机制在很大程度上尚不清楚。我们发现， RPE特异性过度激活雷帕霉素复合物1（mTORC 1）的机制靶点概括了许多 CC脱落的临床特征。mTORC 1活性高的RPE细胞释放的 血管生成素2（ANGPT 2），一种血管不稳定因子，通常由内皮细胞（EC）产生， 并对其受体TIE 2发挥自分泌作用。我们进一步证实了ANGPT 2从RPE的分泌， 可能是由磷蛋白DARPP-32的上调和激活介导的。根据这些小说 研究发现，我们假设ANGPT 2的产生和分泌从RPE有助于变性 在病理条件下，涉及mTORC 1信号失调的脉络膜。假设是 在三个具体目标中进行测试。目的1是确定mTORC 1在RPE中的激活是否会刺激RPE细胞的凋亡。 通过DARPP-32依赖性机制分泌ANGPT 2。目的2是检查ANGPT 2是否可以 通过TIE 2依赖性或非依赖性途径调节脉络膜EC的功能。目标3：确定 无论是RPE中ANGPT 2的基因敲除，还是AAV介导的ANGPT 2的过表达， mTORC 1过度激活小鼠模型中的CC萎缩。这些研究的结果将提供 关于RPE中AMD相关的信令事件如何影响其对CC的支持的见解。新识别的 RPE和脉络膜EC之间的ANGPT 2-TIE 2轴可以是治疗性视网膜脱离的分子途径。 脉络膜萎缩的干预。

The overall goal of the project is to delineate the cellular and molecular mechanisms that link dysfunction of the retinal pigment epithelium (RPE) to degeneration of the choriocapillaris (CC). Choroidal atrophy is an early pathological change in age-related macular degeneration (AMD), a leading cause of blindness in elderly people. The RPE produces a number of trophic factors that support the structural integrity of the choroidal vasculature. Aging and age-related degeneration can interfere with the functional interactions between the RPE and CC. The underlying disease mechanisms are largely unclear. We found that the mouse model of RPE-specific overactivation of the mechanistic target of rapamycin complex 1 (mTORC1) recapitulated many of the clinical features of CC dropout. RPE cells with high mTORC1 activity had increased release of angiopoietin 2 (ANGPT2), a vascular destabilizing factor that is usually produced by endothelial cells (ECs) and exerts autocrine effects on its receptor TIE2. We further identified that the secretion of ANGPT2 from RPE was likely mediated by the upregulation and activation of a phosphoprotein DARPP-32. Based on these novel findings, we hypothesize that ANGPT2 production and secretion from the RPE contribute to the degeneration of choroid under pathological conditions that involve dysregulated mTORC1 signaling. The hypothesis will be tested in three specific aims. Aim 1 is to determine whether mTORC1 activation in the RPE will stimulate ANGPT2 secretion via DARPP-32-dependent mechanisms. Aim 2 is to examine whether ANGPT2 can regulate the function of choroidal ECs via TIE2-dependent or independent pathways. Aim 3 is to determine whether genetic knockout of ANGPT2 in the RPE, or AAV-mediated overexpression of ANGPT2 will influence the CC atrophy in the mouse model of mTORC1 hyperactivation. The results from these studies will provide insights on how the AMD-related signaling events in the RPE impact its support to the CC. The newly identified ANGPT2-TIE2 axis between the RPE and choroidal ECs can be a molecular pathway for the therapeutic intervention of choroidal atrophy.