Targeting YAP with statins to prevent antibody-mediated transplant rejection

摘要 表现出HLA供体特异性抗体（DSA）的实体器官移植受者处于移植物丢失的风险中， 慢性抗体介导的排斥反应（cAMR），并发展为进行性血管疾病， 移植血管病变（TV）。尽管cAMR和TV在不同的疾病中是非常重要的临床问题， 针对HLA I和HLA II的DSA促进cAMR的机制 电视还没有被理解。以前，我们证明DSA诱导的HLA分子连接 在内皮细胞表面表达的蛋白诱导信号通路，包括FAK/Src、PI 3 K/AKT、mTORC 1/2和 ERK调节生存、增殖和迁移，所有这些都与TV高度相关。但关键 由这些信号刺激的转录程序仍有待鉴定。根据新的初步结果， 我们证实转录辅激活因子Yes相关蛋白（雅普）及其旁的WW-domain- 含有具有PDZ结合基序（TAZ）的转录辅激活剂，两种Hippo的中枢效应物 信号通路是由DSA启动的信号级联中的下游汇聚点。虽然抑制 最近的证据表明， 通过他汀类降脂药物靶向雅普/TAZ活性的新途径。重要的是， 流行病学研究强烈表明他汀类药物在临床移植人群中发挥有益作用。 然而，分子机制仍然知之甚少。这种认识上的差距阻碍了有效的 DSA效应子的治疗靶向功能可预防cAMR和TV。这个问题的核心假设是 提示雅普及其周边TAZ在促进内皮细胞增殖和迁移中起着重要作用 以回应DSA。第二个假设是FDA批准的他汀类药物抑制雅普 在这些细胞中发挥作用。因此，他汀类药物可以是预防cAMR的重要因素， 阻断EC中促进生长的雅普/TAZ信号传导。我们将探讨这些假设，通过追求三个 具体目的：1）研究雅普在抗体刺激的人内皮细胞中的调节和功能 直接针对HLA I或HLA II：Src激酶的作用。2)定义他汀类药物抑制雅普的机制 用针对HLA I或HLA II的抗体刺激的EC的功能、增殖和迁移。第三章 使用一种新的心脏移植物同种异体移植物模型表征他汀类药物对体内雅普和cAMR的影响， 发展电视。我们预期雅普/TAZ轴在抗体介导的EC增殖中起关键作用 他汀类药物通过抑制雅普/TAZ抑制EC增殖和TV。如果实验结果证实 根据我们的假设，雅普/TAZ将成为开发新的有效药物的新靶点， DSAs诱导的慢性同种异体移植物损伤。

ABSTRACT Solid organ transplant recipients exhibiting HLA donor specific antibodies (DSA) are at risk for graft loss due to chronic antibody-mediated rejection (cAMR) and develop a progressive vascular disease known as transplant vasculopathy (TV). Although cAMR and TV are highly significant clinical problems across different solid organ transplants the mechanisms by which DSAs directed against HLA I and HLA II contribute to cAMR and TV are not yet understood. Previously, we demonstrated that DSA-induced ligation of HLA molecules expressed in the surface of ECs induces signaling pathways, including FAK/Src, PI3K/AKT, mTORC1/2 and ERK that regulate survival, proliferation and migration, all of which are highly relevant to TV. However, the key transcriptional programs stimulated by these signals remain to be identified. Based on new preliminary results, we posit that the transcriptional co-activator Yes-Associated Protein (YAP) and its paralog WW-domain- containing Transcriptional co-Activator with PDZ-binding motif (TAZ), two central effectors of the Hippo pathway, are downstream points of convergence in the signaling cascade initiated by DSAs. Although inhibition of the activity of transcription factors or their co-activators is a challenging strategy, recent evidence suggests a new avenue to target YAP/TAZ activity via lipid-lowering drugs of the statin family. Importantly, epidemiological studies strongly indicate that statins exert a beneficial effect in clinical transplant populations. However, the molecular mechanism remain poorly understood. This gap in understanding hinders effective therapeutic targeting of DSA effector functions to prevent cAMR and TV. The central hypothesis of this proposal is that YAP and its paralog TAZ play a crucial role in promoting the proliferation and migration of ECs in response to DSAs. A second hypothesis is that the FDA-approved drugs of the statin family inhibit YAP function in these cells. Thus, drugs of the statin family can be an important element in preventing cAMR via blocking growth-promoting YAP/TAZ signaling in ECs. We will explore these hypotheses by pursuing three Specific Aims: 1) Determine the regulation and function of YAP in human ECs stimulated with antibodies directed against HLA I or HLA II: role of Src kinases. 2) Define the mechanism(s) by which statins inhibit YAP function, proliferation and migration of ECs stimulated with antibodies directed against HLA I or HLA II. 3) Characterize the impact of statins on YAP and cAMR in vivo using a novel model of heart graft allograft that develop TV. We anticipate that the YAP/TAZ axis plays a critical role in antibody-mediated EC proliferation and that statins inhibit EC proliferation and TV via YAP/TAZ inhibition. If the experimental results substantiate our hypotheses, YAP/TAZ will emerge as novel targets for developing new and potent drugs for preventing chronic allograft injury induced by DSAs.