Dedicator of cytokinesis 2 in pleural fibrosis

胸膜纤维化是胸膜的瘢痕形成，导致限制性肺病和肺功能受损。的 胸膜纤维化的病理生理机制尚不清楚。居民与 炎性细胞、促纤维化介质和凝血因子以及纤维蛋白溶解途径是 胸膜重塑和纤维化。越来越多的证据证实了胸膜间皮细胞（PMCs）的关键作用 在胸膜纤维化的发展中，主要通过一个称为间皮细胞向间质细胞转化的过程， （MesoMT）。MesoMT的特征在于α-平滑肌肌动蛋白（α-SMA）/胶原1的表达增加 （Col-1）/纤连蛋白（FN），并增强细胞迁移/侵袭。目前，没有药理学 治疗这种疾病。因此，识别新的靶标和治疗策略是重要的。 为公共卫生的目标。然而，在控制MesoMT的机制方面存在根本性的知识差距 胸膜纤维化我们的初步数据有力地支持细胞质分裂的奉献者2（DOCK 2）是一个 MesoMT的重要调节剂，以促进胸膜纤维化。在原代人PMC（HPMC）中，DOCK 2表达为 由有效的MesoMT诱导剂TGF-β诱导。DOCK 2敲低阻断TGFβ诱导的MesoMT标记物 表达和细胞迁移。Snail作为调控上皮细胞向间充质细胞转化的转录因子 发现在TGF-β诱导的MesoMT中至关重要。DOCK 2敲低抑制TGF-β诱导的Snail表达 以及Smad 2/3和NF-κB信号传导的激活，这些信号传导已被证明可以上调Snail的表达。 各种细胞类型。此外，我们发现DOCK 2在人纤维化胸膜中被显著诱导， 胸膜炎患者和肺炎链球菌（Strep）诱导的胸膜纤维化模型中，碳 black/博来霉素（CBB）和TGF-β。DOCK 2基因敲除小鼠显著免受链球菌诱导的 胸膜纤维化基于这些发现，我们的总体假设是DOCK 2介导MesoMT， 增加PMC迁移/侵袭以促进胸膜纤维化，这将在三个特定目标中进行测试。在 目的1，我们将确定DOCK 2是否通过上调Snail促进胸膜MesoMT。此外，我们将测试 DOCK 2是否通过激活Smad 2/3和NF-κB信号通路增加Snail。在目标2中，我们将测试 DOCK 2促进胸膜MesoMT，增加细胞迁移/侵袭。具体来说，我们将确定， DOCK 2通过激活Rac 1介导TGF-β诱导的细胞骨架重组、迁移/侵袭。在目标3中， 我们将检验DOCK 2敲除通过体内抑制MesoMT阻断胸膜纤维化的假设。我们将 确定一般和间皮细胞特异性DOCK 2敲除小鼠是否受到链球菌、CBB和 TGF-β通过抑制MesoMT诱导胸膜纤维化。完成拟议的研究将 建立DOCK 2通过调节MesoMT促进胸膜纤维化的关键作用和机制， 这可能最终有助于确定这种重要但难治的新型靶向治疗方法， 临床问题

Pleural fibrosis is the scarring of the pleura resulting in restrictive lung disease and impaired lung function. The pathophysiological mechanism of pleural fibrosis is unclear. The interactions between resident and inflammatory cells, profibrotic mediators and coagulation factors, and fibrinolytic pathways are integral to pleural remodeling and fibrosis. Increasing evidence affirm the critical role of pleural mesothelial cells (PMCs) in pleural fibrosis development, mainly through a process termed mesothelial to mesenchymal transition (MesoMT). MesoMT is characterized by increased expression of α-smooth muscle actin (α-SMA)/collagen 1 (Col-1)/fibronectin (FN), and enhanced cell migration/invasion. Currently, there are no pharmacologic treatments for this disease. Therefore, identification of novel targets and therapeutic strategies is an important goal for the public health. However, there is a fundamental knowledge gap in mechanisms controlling MesoMT during pleural fibrosis. Our preliminary data strongly support that dedicator of cytokinesis 2 (DOCK2) is a crucial regulator of MesoMT to promote pleural fibrosis. In primary human PMCs (HPMCs), DOCK2 was induced by the potent MesoMT inducer TGF-β. DOCK2 knockdown blocked TGFβ-induced MesoMT maker expression and cell migration. Snail as a transcriptional factor controlling epithelial to mesenchymal transition was found critical in TGF-β-induced MesoMT. DOCK2 knockdown inhibited TGF-β-induced Snail expression and activation of Smad2/3 and NF-κB signaling, which have been shown to upregulate Snail expression in various cell types. In addition, we found that DOCK2 was dramatically induced in the fibrotic pleura of human pleuritis patients and in pleural fibrosis models induced by Streptococcus pneumoniae (Strep), carbon black/bleomycin (CBB), and TGF-β. DOCK2 knockout mice were significantly protected from Strep-induced pleural fibrosis. Based on these findings, our overall hypothesis is that DOCK2 mediates MesoMT and increases PMC migration/invasion to promote pleural fibrosis, which will be tested in three specific aims. In Aim 1, we will determine if DOCK2 promotes pleural MesoMT via upregulation of Snail. Further, we will test whether DOCK2 increases Snail through activating Smad2/3 and NF-κB signaling. In Aim 2, we will test if DOCK2 promote pleural MesoMT with increased cell migration/invasion. Specifically, we will determine if DOCK2 mediates TGF-β-induced cytoskeletal reorganization, migration/invasion via activating Rac1. In Aim 3, we will test the hypothesis that DOCK2 knockout blocks pleural fibrosis via inhibiting MesoMT in vivo. We will determine if general and mesothelial cell-specific DOCK2 knockout mice are protected from Strep, CBB, and TGF-β induced pleural fibrosis through suppressing MesoMT in vivo. Completion of the proposed studies will establish the pivotal role and mechanisms of DOCK2 in promoting pleural fibrosis by regulating MesoMT, which may ultimately contribute to the identification of novel targeted therapies for this important but refractory clinical problem.