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 肺内肺动脉微灌流回路的肌化和阻塞。我们建议， PAH的病理生物学表现为一种功能障碍的血管周围伤口愈合反应，其基础是 新近发现的PUR？DNA结合蛋白抑制转化生长因子？1信号转导能力的缺陷 阿龙。由于未经控制的协同作用导致伤口修复基因的过度转录激活 血清反应因子(SRF)和转化生长因子β1调节的Smad蛋白2和3之间的关系导致加速 小动脉周围肌成纤维细胞分化与外膜纤维化伴肺动脉缺失 依从性和最终的右心衰竭。Smads 2和3正常情况下解离基因抑制SRF-pur？ 允许激活平滑肌肌动蛋白(SM？A)和I型胶原？2亚单位的蛋白质复合体 启动子是最惠国分化过程中的第一步。我们将检验这样的假设：SRF-PUR？ 由于PI3K/Akt前馈信号过度活跃，多环芳烃衍生的MFBs中抑制复合体不稳定 次优的MEK1/Erk1，2/Egr-1信号介导的激酶和/或减弱的反馈抑制。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划。 与IPAH/FPAH综合征小动脉周围肌成纤维细胞分化和重塑有关 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 表观遗传学/代谢方法在IPAH/FPAH综合征小动脉周围肌成纤维细胞分化中的应用 靶向SRF-pur在分离的正常或正常肺血管外膜成纤维细胞中的物理相互作用 受疾病影响的捐赠者。我们已经开发了用于定量评估蛋白质的固相酶联免疫吸附试验工具：蛋白质 和蛋白质：DNA相互作用，独特地调节外膜MFB分化的过程。这个 能够触发原型基因反应的特殊转录调控复合体的组装 代表了复杂的血管疾病信号的汇聚点 补偿性的和特定于患者的控制层。我们预计，所获得的知识可以进一步基本 了解导致动脉顺应性丧失的限速性相互作用，通常与 最具破坏性的IPAH/FPAH疾病综合征。未来详细的蛋白质生物化学分析 激活剂-抑制物的动态相互作用可揭示肺肿瘤治疗的新靶点 动脉疾病和右心衰竭，最终可能会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.