BMP2/ALKs signaling system in diabetic retinopathy

总结 血-视网膜屏障（BRB）的破坏和内皮细胞基底膜的增厚， 细胞外基质（ECM）沉积是糖尿病视网膜病变（DR）发病的早期事件。 目前的治疗受到显著副作用的限制，包括ECM沉积。骨形态发生蛋白- 2（BMP 2），一种属于TGF-β超家族的分泌型细胞因子，通过激活素受体启动信号传导 类似激酶（Alk 1、2、3和6），对Alk 2和3具有高亲和力。这个项目的目标是检验这个假设 在糖尿病中，BMP2通过内皮Alk2/3依赖性的细胞外基质诱导BRB和ECM形成。 机制我们的假设得到了令人信服的初步发现的支持，视网膜和循环中的BMP 2 在糖尿病人和小鼠中，以及在经历了以下过程的人视网膜内皮细胞（HREC）中上调： 高血糖（HG）。重要的是，BMP 2抑制剂减弱HG的渗透性和ECM沉积作用， 在人权和环境委员会。此外，BMP 2激活经典和非经典途径（smad/Runx2和p38 MAPK/NF κ B（分别为B）。我们的假设预测，在糖尿病中，BMP 2激活smad和p38， MAPK通路在wnt/β-连环蛋白处整合以诱导高通透性和ECM沉积。我们将测试 具体目标：1。激活的BMP-2/Alks信号系统促进视网膜内皮细胞 DR的功能障碍：我们将使用 来自糖尿病表型和基因组的糖尿病患者大队列的血清样本 自身免疫（PAGODA）研究，并已前瞻性监测糖尿病的发展 包括DR在内的并发症。使用链脲佐菌素诱导的糖尿病小鼠模型， HREC经HG处理后，我们将测定BMP 2信号系统（BMP 2，BMP 4， BMP受体、smad1/5/9、Runx2和BMP 2的负调节因子，如头蛋白和BMP结合内皮细胞 调节器（BMPER）。随后，我们将研究药物抑制或遗传操作的影响 BMP 2/Alks系统的BRB功能和ECM。我们将使用内皮Alk2/3条件性敲除小鼠 在我们的实验室内开发和商业上可获得的BMPER缺陷小鼠（BMPER +/−）和; 2.既规范 和非经典途径有助于DR中BMP 2介导的视网膜内皮细胞功能障碍：我们 将测试a）在正常条件下BMP 2/Alks信号传导的调节对smad1/5/9和p38/NF κ B B通路的影响 B）抑制smad 1/5/9或p38/NF κ B B信号传导对糖尿病或BMP 2诱导的糖尿病的影响， c）wnt/β-catenin通路作为潜在的下游调节因子的作用， 从p38/NF κ B B和smad 1/5/9途径靶向介导由BMP 2诱导的视网膜微血管损伤。 该提议的翻译意义在于抑制BMP 2/Alks信号传导的治疗潜力 改善DR中的视觉结果，最终目标是克服电流的限制因素 预防ECM沉积的治疗。

Summary Breakdown of the blood-retinal barrier (BRB) and thickening of the endothelial cell basement membrane due to deposition of extracellular matrix (ECM) are early events in the pathogenesis of diabetic retinopathy (DR). Current treatments are limited by significant side effects, including ECM deposition. Bone morphogenetic protein- 2 (BMP2), a secreted cytokine belonging to the TGF-β superfamily initiates signaling through activin receptors like kinases (Alk1, 2, 3, and 6) with high affinity to Alk2 and 3. The goal of this project is to test the hypothesis that in diabetes, BMP2 compromises BRB and induces ECM formation through the endothelial Alk2/3-dependent mechanism. Our hypothesis is supported by compelling preliminary findings that retinal and circulating BMP2 are upregulated in diabetic humans and mice, as well as in human retinal endothelial cells (HRECs) subjected to high glucose (HG). Importantly, BMP2 inhibitors attenuate the permeability and ECM deposition effect of HG in HRECs. Moreover, BMP2 activates the canonical and non-canonical pathways (smad/Runx2 and p38 MAPK/NFB, respectively) in HRECs. Our hypothesis predicts that in diabetes BMP2 activates smad and p38 MAPK pathways integrate at wnt/-catenin to induce hyperpermeability and ECM deposition. We will test the following specific aims: 1. Activated BMP2/Alks signaling system contributes to retinal endothelial cell dysfunction in DR: We will correlate changes in circulating levels of BMPs to the development of DR using serum samples from a large cohort of diabetic patients enrolled in the Phenome and Genome of Diabetes Autoimmunity (PAGODA) study and have been prospectively monitored for the development of diabetic complications including DR in the last 15 years. Using a streptozotocin-induced diabetic mouse model, and HRECs subjected to HG, we will determine the levels and distribution of BMP2 signaling system (BMP2, BMP4, BMP receptors, smad1/5/9, Runx2, and negative regulators of BMP2 such as noggin and BMP-binding endothelial regulator (BMPER). Subsequently, we will study the effects of pharmacological inhibition or genetic manipulation of the BMP2/Alks system on BRB function, and ECM. We will use endothelial Alk2/3 conditional knockout mice developed within our lab and commercially available BMPER-deficient mice (BMPER+/−) and; 2. Both canonical and non-canonical pathways contribute to BMP2-mediated retinal endothelial cell dysfunction in DR: We will test a) the effect of modulation of BMP2/Alks signaling on the smad1/5/9 and p38/NFB pathways under normal or diabetic conditions, b) the effect of inhibition of smad1/5/9 or p38/NFB signaling on diabetes or BMP2-induced permeability and ECM deposition, and c) the role of the wnt/catenin pathway as a potential downstream target from both p38/NFB and smad1/5/9 pathways to mediate retinal microvascular damage induced by BMP2. The translational significance of this proposal is the therapeutic potential of inhibition of BMP2/Alks signaling to improve the visual outcomes in DR with the ultimate goal of overcoming the limiting factors of current therapies in the prevention of ECM deposition.