Peri-arteriolar Myofibroblast Differentiation in the Pathobiology of IPAH

摘要 特发性和家族性肺动脉高压综合征（IPAH/FPAH）通常与以下疾病相关： 肺内肺动脉微灌注回路的肌肉化和阻塞。我们建议 肺动脉高压的病理生物学代表了基于功能性炎症的功能失调的血管周围伤口愈合反应 最近发现的Pur <$DNA结合蛋白抑制TGF <$1信号传导的能力不足， 肺。过度转录激活伤口愈合基因由于未经检查的协作相互作用 血清反应因子（SRF）和TGF β 1调节的Smad蛋白2和3之间的关系导致加速的 动脉周围肌成纤维细胞（MFB）分化和外膜纤维化伴肺动脉缺失 顺应性和最终的右心衰竭。Smads 2和3通常解离基因抑制性SRF-Pur？ 蛋白复合物，允许激活平滑肌肌动蛋白（SM <$A）和I型胶原蛋白<$2亚基 启动子作为MFB分化过程的第一步。我们将测试的假设，SRF-Pur？ 由于过度活跃的PI 3 K/Akt前馈信号，抑制复合物在PAH衍生的MFB中不稳定 激酶和/或由次优MEK 1/Erk 1，2/Egr-1信号传导介导的反馈抑制受损。在目标1中， 我们建议描述转录激活因子和抑制因子的亚细胞区室化 在IPAH/FPAH综合征中涉及动脉周围肌成纤维细胞分化和重塑， 免疫细胞化学方法。对于目标2，我们将定义导致过量的生化功能障碍， 应用表观遗传/代谢方法研究IPAH/FPAH综合征的动脉周围肌成纤维细胞分化 靶向SRF-Pur在肺动脉外膜成纤维细胞中的物理相互作用， 受疾病影响的捐赠者。我们已经开发了固相ELISA工具来定量评估蛋白质：蛋白质 和蛋白质：DNA的相互作用，独特地调节外膜MFB分化的过程。的 能够触发原型基因反应的特化转录调控复合物的组装 在MFB中，代表了由多个血管疾病信号传导组成的复杂血管疾病信号传导的汇聚点。 补偿和患者特定的控制层。我们希望所获得的知识能够进一步促进 了解速率限制相互作用，促进动脉顺应性的损失，通常与 最具破坏性的IPAH/FPAH疾病综合征。未来的蛋白质生化详细分析 激活物-抑制物的动态相互作用可能揭示肺结核治疗管理的新靶点。 动脉疾病和右心衰竭，最终可能改善患者的长期生存。

ABSTRACT Idiopathic and familial syndromes of pulmonary arterial hypertension (IPAH/FPAH) typically are associated with muscularization and obstruction of pulmonary arterial microperfusion circuits in the lung. We propose that the pathobiology of PAH represents a dysfunctional, peri-vascular wound healing response based on a functional deficit in the ability of the recently discovered Pur ¿ DNA-binding protein to repress TGF¿1 signaling in the lung. Excessive transcriptional activation of wound-healing genes due to unchecked collaborative interaction between serum response factor (SRF) and TGF¿1-regulated Smad proteins 2 and 3 results in accelerated peri-arteriolar myofibroblast (MFB) differentiation and adventitial fibrosis with loss of pulmonary arterial compliance and eventual right heart failure. Smads 2 and 3 normally dissociate gene-inhibitory SRF-Pur ¿ protein complexes to allow activation of the smooth muscle ¿-actin (SM¿A) and type I collagen ¿2-subunit promoters as a first step in the MFB differentiation process. We will test the hypothesis that the SRF-Pur¿ inhibitory complex is unstable in PAH-derived MFBs due to over-active PI3K/Akt feed-forward signaling kinases and/or impaired feed-back inhibition mediated by sub-optimal MEK1/Erk1,2/Egr-1 signaling. In Aim 1, we propose to characterize the sub-cellular compartmentalization of transcriptional activators and repressors implicated in peri-arteriolar myofibroblast differentiation and remodeling in IPAH/FPAH syndromes using an immunocytochemistry approach. For Aim 2, we will define the biochemical dysfunction that causes excess peri-arteriolar myofibroblast differentiation in IPAH/FPAH syndromes using epigenetic/metabolic approaches that target SRF-Pur ¿ physical interplay in pulmonary artery adventitial fibroblasts isolated from normal or disease-affected donors. We have developed solid-phase ELISA tools to quantitatively evaluate protein:protein and protein:DNA interactions that uniquely regulate the process of adventitial MFB differentiation. The assembly of a specialized transcriptional regulatory complex capable of triggering prototypical gene responses in MFBs represents a convergence point for complex vascular-disease signaling consisting of multiple compensatory and patient-specific layers of control. We expect that knowledge gained could further basic understanding of rate-limiting interactions that foster loss of arterial compliance typically associated with the most devastating IPAH/FPAH disease syndromes. Future detailed analysis of the protein biochemistry of activator-repressor dynamic interplay could reveal novel targets for therapeutic management of pulmonary arterial disease and right heart failure that may ultimately improve patient long-term survival.