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有因移植物丢失的风险 慢性抗体介导的排斥反应 (cAMR) 并发展为进行性血管疾病，称为 移植血管病变（TV）。尽管 cAMR 和 TV 在不同领域都是非常重要的临床问题 实体器官移植 针对 HLA I 和 HLA II 的 DSA 促进 cAMR 的机制 和电视还没有被理解。之前，我们证明了 DSA 诱导的 HLA 分子连接 ECs表面表达诱导信号通路，包括FAK/Src、PI3K/AKT、mTORC1/2和 ERK 调节生存、增殖和迁移，所有这些都与电视高度相关。然而，关键 这些信号刺激的转录程序仍有待鉴定。根据新的初步结果， 我们假设转录共激活因子 Yes-Associated Protein (YAP) 及其旁系同源 WW-domain- 含有具有 PDZ 结合基序 (TAZ) 的转录共激活剂，这是 Hippo 的两个中心效应器 路径，是 DSA 发起的信号级联中的下游汇聚点。虽然抑制 最近的证据表明，转录因子或其共激活子的活性是一项具有挑战性的策略 通过他汀类降脂药物靶向 YAP/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对临床移植人群发挥有益作用。 然而，其分子机制仍知之甚少。这种理解上的差距阻碍了有效的 治疗靶向 DSA 效应器功能以预防 cAMR 和 TV。这个假设的中心假设 提议认为YAP及其旁系同源物TAZ在促进EC的扩散和迁移中发挥着至关重要的作用 响应 DSA。第二个假设是 FDA 批准的他汀类药物抑制 YAP 在这些细胞中发挥作用。因此，他汀类药物可以通过以下途径成为预防 cAMR 的重要因素： 阻断 EC 中促进生长的 YAP/TAZ 信号传导。我们将通过追求三个方面来探索这些假设 具体目标： 1) 确定 YAP 在抗体刺激的人 EC 中的调节和功能 针对 HLA I 或 HLA II：Src 激酶的作用。 2) 定义他汀类药物抑制 YAP 的机制 使用针对 HLA I 或 HLA II 的抗体刺激 EC 的功能、增殖和迁移。 3） 使用新型心脏移植同种异体移植模型表征他汀类药物对体内 YAP 和 cAMR 的影响，该模型 发展电视。我们预计 YAP/TAZ 轴在抗体介导的 EC 增殖中发挥关键作用 他汀类药物通过抑制 YAP/TAZ 来抑制 EC 增殖和 TV。如果实验结果证实 我们的假设是，YAP/TAZ 将成为开发新的有效药物来预防疾病的新靶标。 DSA 引起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.