Transcriptional and epigenetic control of angiogenic genes in sepsis-induced acute kidney injury.

脓毒症引起的急性肾损伤(AKI)是最常见和危及生命的肾损伤原因。 危重病人。然而，败血症AKI的治疗几十年来没有任何改善。 败血症AKI与非感染性AKI不同；值得注意的是--表现为低血流量的微循环功能障碍， 血管内皮细胞(EC)激活和血管渗漏，在发病中起着突出的病理作用。微血管系统 由管腔内皮细胞和周细胞组成，环绕管腔内皮壁。EC受体酪氨酸 激酶，Tie-2(TEK)及其两个配体，Ang-1和Ang-2，即Ang-Tie-2 轴)调节微血管系统。周细胞是Ang-1的主要来源，Ang-1通过 Tie-2信令。Tie-2的表达/信号在一定程度上受血流调节，这一过程涉及 转录因子KLF2。Tie-2和Ang-1基因在脓毒症肾脏中表达下调，参与EC的发生 功能障碍。Tie-2/Ang-1表达的变化与表观遗传学改变和KLF2基因缺失相关 这些轨迹。我们将检验脓毒症导致KLF2从Ang-1和Tie-2上解脱的假设 基因改变Ang-1和Ang-1相互作用的转录和表观遗传因子的动态网络(S) Tie-2基因座下调其转录，导致内皮细胞泄漏。 目的#1.定义与以下相关的转录/表观遗传网络变化动力学 KLF2在脓毒症小鼠模型中从肾脏Ang-1和Tie-2基因中解离。关联动力学 脓毒症诱导的肾脏Ang-1和Tie-2基因转录/表观遗传改变与进展 内皮泄漏将确定KLF2依赖和独立的相互作用，这将在体外进行测试(AIMS#2-3) 它们在Tie-2和Ang-1表达中的作用。 目的#2.使用EC和周细胞培养来确定染色质结合的哪些相互作用 蛋白质作用(相加、协同或拮抗)调节Tie-2和Ang-1转录。 Tie-2和Ang-1抑制的机制将通过击倒/抑制候选因子(例如， HDAC)被拴在这些基因座上。 目的#3.确定Tie-2和Ang-1上哪种转录/表观遗传因子相互作用 基因座对血流/炎症介质有反应，并调节微血管屏障。 流动的微血管。我们将利用我们的人造人肾微血管来模拟内皮 泄漏以确定调节Ang-1和Tie-2基因的流动响应性转录/表观遗传相互作用。 我们最近展示了先前未曾预料到的基因的表观遗传异质性和唯一性。 在AKI期间的响应。因此，定义在Ang-1参与的关键转录/表观遗传网络组件和 Tie-2基因作为潜在的药物靶点，将为未来合理组合检测提供翻译基础。 设计药物干预措施，以减轻脓毒症期间的微血管渗漏和肾脏损伤。

Sepsis-induced acute kidney injury (AKI) is the most common and life-threatening cause of renal injury in critically ill patients. And yet, there have been no improvements in the treatment of septic AKI in decades. Septic AKI is distinct from non-septic AKI; notably - microcirculatory dysfunction manifested by low blood flow, endothelial cell (EC) activation and vascular leak, play a prominent pathologic roles. The microvasculature consists of luminal EC and pericytes, which encircle the abluminal endothelial wall. The EC receptor tyrosine kinase, Tie-2 (TEK), and its two ligands, angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), (i.e., Ang-Tie-2 axis) regulate microvasculature. Pericytes are the primary source of Ang-1, which maintains EC quiescence via Tie-2 signaling. Tie-2 expression/signaling is, part, regulated by blood flow, a process that involves transcription factor, Klf2. Tie-2 and Ang-1 gene expression is downregulated in septic kidney, contributing to EC dysfunction. Changes in Tie-2/ Ang-1 expression are associated with epigenetic alterations and loss of Klf2 at these loci. We will test the hypothesis that sepsis-induced Klf2 disengagement from Ang-1 and Tie-2 genes alters dynamic network(s) of transcription and epigenetic factors interacting along Ang-1 and Tie-2 loci which down-regulates their transcription and contributes to endothelial leak. Aim #1. To define kinetics of transcription/epigenetic network changes associated with disengagement of Klf2 from renal Ang-1 and Tie-2 genes in mouse models of sepsis. Correlating kinetics of sepsis-induced transcription/epigenetic alterations at the renal Ang-1 and Tie-2 genes with progression to endothelial leak will identify Klf2-dependent and -independent interactions that will be tested in vitro (Aims #2-3) for their role inTie-2 and Ang-1 expression. Aim #2. To use EC and pericyte cultures to define which interactions of chromatin-bound proteins act (additively, synergistically or antagonistically) to regulate Tie-2 and Ang-1 transcription. Mechanism of Tie-2 and Ang-1 repression will be studied by knocking down/inhibiting candidate factors (e.g., HDACs) tethered to these loci. Aim #3. To characterize which of transcription/epigenetic factor interactions at Tie-2 and Ang-1 loci are responsive to flow/inflammatory mediators and regulate microvascular barrier in in vitro 3D- flow microvessels. We will take advantage of our synthetic human kidney microvessels that model endothelial leak to identify flow-responsive transcription/epigenetic interactions that regulate Ang-1 and Tie-2 genes. We have recently demonstrated, previously unanticipated, epigenetic heterogeneity and uniqueness of gene responses during AKI. Thus, defining key transcription/epigenetic network components engaged at Ang-1 and Tie-2 genes as potential drug targets will provide translational basis for future testing combinatorial rationally- designed pharmacologic interventions to mitigate microvascular leak and kidney injury during sepsis.