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

项目总结 肺动脉高压(PAH)是一种使人衰弱并最终致命的疾病，它对 目前的治疗方法。PAH的一个明显特征是细胞过度增殖和重塑 肺动脉(PA)，导致肺血管阻力进行性增加导致右 心力衰竭和死亡。PAH在确诊后的存活时间为五到七年，而大多数 目前治疗PAH的方法是血管扩张剂，可以缓解症状，但不能逆转肺循环 血管重塑或阻止疾病进展。我们发现了一种新的基因--PDZ结合激酶(PBK) 这在高血压的PA中表达上调。PBK是一种丝氨酸/苏氨酸激酶，在 侵袭性癌症。PAH中血管细胞的过度增殖特性与此有许多共同的机制 然而，针对癌细胞的靶向PBK在PAH中的治疗作用以及PBK 目前尚不清楚对肺血管重塑的影响，这是本研究的目标。 在实验模型和人类PAH的初步实验中，我们表明PBK是健壮的 在PA的内侧层表达上调，在那里它与平滑肌细胞的标记重叠。的得失 功能研究表明，PBK表达对肺动脉平滑肌细胞(PASMC)有调节作用 扩散。在实验大鼠和小鼠体内PAH模型中，我们发现PBK的选择性抑制剂 改善PA重塑和心肺功能。以确定增加的潜在机制 在PBK的表达中，我们发现转录共激活因子YAP1是 PASMC中PAH表达上调，PBK启动子活性和PBK蛋白表达增加。我们雇佣了 近距离连接方法鉴定具有胞质分裂调节功能的PBK新底物 1(PRC1)作为结合伙伴。PBK上调PRC1的表达并诱导其磷酸化和胞质分裂 PASMC。这些新的初步数据提供了我们的中心假设，即YAP1上调PASMC中的PBK以 通过Prc1介导的胞质分裂促进增殖。总而言之，这些机制导致了 肺血管重构与肺动脉高压。这一假设将通过整合分子、细胞、 包括PBK KO在内的多种啮齿动物模型的遗传、成像和翻译药理学方法 老鼠。我们的长期目标是确定PBK调节PASMC增殖的关键机制 协调动脉重塑的变化，这是PAH的一个标志。在其结论中，拟议的研究将 通过定义PAH中新的信号通路和PASMC的新机制来推动该领域的发展 扩散。这些研究还将促进针对PBK和PBK的新治疗方法的应用 胞质分裂可减少PA重塑，从而改善与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.