PBK: A novel mediator of VSMC proliferation and vascular remodeling in PAH

项目摘要 肺动脉高压（PAH）是一种使人衰弱并最终致命的疾病， 目前的治疗。PAH的一个定义特征是过度的细胞增殖和 肺动脉（PA），导致肺血管阻力进行性增加，导致右 心室衰竭和死亡。PAH在诊断后的生存时间为5至7年，大多数 目前PAH的治疗方法是血管扩张剂，可缓解症状，但不能逆转肺动脉高压。 血管重塑或阻止疾病进展。我们发现了一个新的基因，PDZ结合激酶（PBK） 在高血压PA中上调。PI 3 K是一种丝氨酸/苏氨酸激酶，其在一个亚群中过表达， 侵袭性癌症PAH中血管细胞的过度增殖性质与PAH中血管细胞的过度增殖有许多共同的机制， 然而，靶向PBK在PAH中的治疗效用以及PBK 影响肺血管重塑的因素尚不清楚，这是本提案的目标。 在实验模型和人类PAH的初步实验中，我们表明PBK是稳健的， 在PA的中间层中上调，其中它与平滑肌细胞的标记物重叠。得与失 功能研究表明，PBK表达调节肺动脉平滑肌细胞（PASMC） 增殖在PAH的大鼠和小鼠体内实验模型中，我们发现选择性的PBK抑制剂， 改善肺动脉重塑和心肺功能。确定增加的潜在机制 在PBK表达的过程中，我们发现转录辅激活因子是相关蛋白1（YAP 1）， 在PAH中上调，并增加PASMC中的PI 3 K启动子活性和PI 3 K蛋白表达。我们采用 用邻位连接法鉴定揭示胞质分裂调节蛋白的PBK新底物 1（PRC 1）作为结合伴侣。PBK上调PRC 1并诱导PRC 1磷酸化和胞质分裂， PASMC。这些新的初步数据提示了我们的中心假设，即YAP 1上调PASMC中的PBMC， 通过PRC 1介导的胞质分裂增强增殖。这些机制共同导致病理性 肺血管重塑和PAH。这一假设将使用整合的分子，细胞， 在多种啮齿动物模型中的遗传、成像和转化药理学方法，包括PBK KO 大鼠我们的长期目标是确定PBMC调节PASMC增殖的关键机制， 协调动脉重塑的变化，这是PAH的标志。在研究结束时，拟议的研究将 通过定义PAH中的新信号通路和PASMC的新机制，推动该领域向前发展 增殖这些研究还将推进靶向PI 3 K和PI 3 K受体的新型治疗方法的实用性。 胞质分裂减少PA重塑，随后改善PAH相关的发病率和死亡率。

PROJECT SUMMARY Pulmonary Arterial Hypertension (PAH) is a debilitating and eventually lethal disease that is resistant to current therapeutics. A defining characteristic of PAH is excessive cellular proliferation and remodeling of pulmonary arteries (PA), that results in progressive increases in pulmonary vascular resistance leading to right ventricular failure and death. PAH has a survival time of five to seven years post diagnosis, and most of the current therapies for PAH are vasodilators, which provide symptomatic relief, but do not reverse pulmonary vascular remodeling or stop disease progression. We have discovered a novel gene, PDZ-Binding Kinase (PBK) that is upregulated in hypertensive PA. PBK is a serine/threonine kinase that is overexpressed in a subset of aggressive cancers. The hyperproliferative nature of vascular cells in PAH shares many mechanisms with that of cancer cells, however, the therapeutic utility of targeting PBK in PAH and the mechanisms by which PBK influences pulmonary vascular remodeling are not yet known and are the goals of this proposal. In preliminary experiments in experimental models and human PAH, we show that PBK is robustly upregulated in the medial layer of PA where it overlaps with markers of smooth muscle cells. Gain and loss of function approaches show that PBK expression regulates pulmonary artery smooth muscle cell (PASMC) proliferation. In experimental rat and mouse models of PAH in vivo, we found that selective inhibitors of PBK improve PA remodeling and cardiopulmonary function. To determine the mechanisms underlying increased expression of PBK, we found that the transcriptional co-activator, Yes Associated Protein1 (YAP1) was upregulated in PAH and increased PBK promoter activity and PBK protein expression in PASMC. We employed a proximity ligation approach to identify novel substrates of PBK which revealed Protein Regulator of Cytokinesis 1 (PRC1) as a binding partner. PBK upregulated PRC1 and induced PRC1 phosphorylation and cytokinesis in PASMC. These novel preliminary data inform our central hypothesis that YAP1 upregulates PBK in PASMC to enhance proliferation via PRC1 mediated cytokinesis. Collectively these mechanisms contribute to pathologic pulmonary vascular remodeling and PAH. This hypothesis will be tested using integrated molecular, cellular, genetic, imaging, and translational pharmacological approaches in multiple rodent models including a PBK KO rat. Our long-term goal is to define the key mechanisms by which PBK regulates PASMC proliferation to orchestrate changes in arterial remodeling, a hallmark of PAH. At their conclusion, the proposed studies will move the field forward by defining novel signaling pathways in PAH and a novel mechanism of PASMC proliferation. These studies will also advance the utility of novel therapeutic approaches targeting PBK and cytokinesis to reduce PA remodeling and subsequently improve the morbidity and mortality associated with PAH.