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 肺部肺动脉微灌注回路的肌肉化和阻塞。我们建议 PAH 的病理学代表了一种基于功能性功能障碍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 信号传导的能力缺陷 肺。由于不受控制的协作相互作用导致伤口愈合基因过度转录激活 血清反应因子 (SRF) 和 TGF¿1 调节的 Smad 蛋白 2 和 3 之间的相互作用导致加速 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 依从性和最终的右心衰竭。 Smads 2 和 3 通常会解离基因抑制性 SRF-Pur ¿ 蛋白质复合物，可激活平滑肌 ¿-肌动蛋白 (SM¿A) 和 I 型胶原 ¿2 亚基 启动子作为 MFB 分化过程的第一步。我们将检验 SRF-Pur¿ 由于 PI3K/Akt 前馈信号过于活跃，抑制复合物在 PAH 衍生的 MFB 中不稳定 激酶和/或由次优 MEK1/Erk1,2/Egr-1 信号传导介导的反馈抑制受损。在目标 1 中， 我们建议表征转录激活因子和阻遏因子的亚细胞区室化 使用一种方法参与 IPAH/FPAH 综合征中小动脉周围肌成纤维细胞的分化和重塑 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 使用表观遗传/代谢方法研究 IPAH/FPAH 综合征的小动脉周围肌成纤维细胞分化 靶向 SRF-Pur ¿ 在从正常或正常肺动脉中分离出的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。我们开发了固相 ELISA 工具来定量评估蛋白质：蛋白质 以及蛋白质：DNA 相互作用，独特地调节外膜 MFB 分化过程。的 能够触发原型基因反应的专门转录调控复合物的组装 MFB 中的 MFB 代表由多个组成的复杂血管疾病信号传导的汇聚点 补偿性和患者特定的控制层。我们希望所获得的知识能够进一步加深基础知识 了解限速相互作用，这些相互作用会导致动脉顺应性丧失，通常与 最具破坏性的 IPAH/FPAH 疾病综合征。未来蛋白质生物化学的详细分析 激活剂-阻抑剂的动态相互作用可以揭示肺结核治疗管理的新靶点 动脉疾病和右心衰竭可能最终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.