Targeting YAP with statins to prevent antibody-mediated transplant rejection

摘要 表现出人类白细胞抗原供者特异性抗体(DSA)的实体器官移植受者面临移植物丢失的风险 导致慢性抗体介导的排斥反应(CAMR)，并发展为一种进行性血管疾病，称为 移植血管病(TV)。尽管CAMR和TV是不同领域中非常重要的临床问题 实体器官移植中针对HLAI和HLAII的DSA参与CAMR的机制 和电视还不是很清楚。以前，我们证明了DSA诱导的人类白细胞抗原分子的连接 在内皮细胞表面表达可诱导多种信号转导途径，包括FAK/Src、PI3K/AKT、mTORC1/2和 调节生存、扩散和迁移的ERK，所有这些都与电视高度相关。然而，关键是 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， 我们假设转录共激活因子YAP及其类似的WW结构域-- 含有带有PDZ结合基序的转录共激活因子(TAZ)，河马的两个中央效应器 途径，是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，转录因子或其共激活子的活性是一种具有挑战性的策略 通过他汀类降脂药物靶向YAP/TAZ活性的新途径。重要的是 流行病学研究有力地表明，他汀类药物在临床移植人群中发挥着有益的作用。 然而，其分子机制仍然知之甚少。这种理解上的差距阻碍了有效的 治疗靶向的DSA效应器功能，以预防CAMR和TV。这一点的中心假设是 建议YAP及其邻近的TAZ在促进内皮细胞的增殖和迁移方面发挥关键作用 作为对DSA的回应。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，他汀类药物可以成为预防CAMR的重要因素。 阻断内皮细胞中促进生长的YAP/TAZ信号。我们将通过追求三个假设来探索这些假说 具体目的：1)确定抗体刺激的人内皮细胞中YAP的调节和功能 针对HLAI或HLAII：Src激酶的作用。2)明确他汀类药物抑制YAP的机制(S) 抗HLAI或HLAII型抗体刺激内皮细胞的功能、增殖和迁移 使用一种新的同种异体心脏移植模型，在体内表征他汀类药物对YAP和CAMR的影响 发展电视。我们推测YAP/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YAP/TAZ抑制EC增殖和TV。如果实验结果证明 我们的假设，YAP/TAZ将成为开发新的有效预防药物的新靶点 DSAs诱导的慢性同种异体移植损伤。

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.