The role of YAP1 in angiogenesis during organ regeneration

项目摘要： 血管生成-新毛细血管的形成-在器官再生中起着关键作用。因而为了 再生成人器官，我们需要了解器官再生过程中血管生成的机制。它 据报道，成人肺在单侧肺切除术（PNX）后具有生长潜力， 抑制血管生成会损害成年小鼠PNX后肺的生长。本提案的总体目标是 以肺为模型， 这一知识，以制定一个有效的战略，器官再生。机械敏感性转录辅因子 激活子，Yes相关蛋白（YAP 1）和具有PDZ结合基序的转录共激活子（TAZ）， 刺激血管生成并控制器官大小和再生。在肺中，肺泡干中的YAP 1活化 细胞促进PNX后肺生长。然而，内皮细胞YAP 1/TAZ在术后血管生成中的作用尚不清楚。 PNX肺生长仍不清楚。我们的初步数据表明，敲除YAP 1和/或TAZ 降低内皮细胞（EC）中血管生成因子受体Tie 2的表达，抑制EC 发芽单侧PNX后，YAP 1/TAZ和Tie 2的表达增加，血管密度增加， 剩下的肺叶PNX后的代偿性肺生长在VE-钙粘蛋白特异性Yap 1和/或 Taz敲除（Yap 1fl/fl-Cdh 5CreERT 2、Yap 1 i ΔEC、Taz iΔEC或Yap 1/TaziΔEC）小鼠在他莫昔芬诱导后 Yap 1/Taz缺失。当我们将纤维蛋白凝胶植入到对照Yap 1fl/fl小鼠肺时， 宿主肺，并在植入的凝胶中形成血管网络，而在植入的凝胶中血管形成减弱。 凝胶植入Yap 1f 1/fl-Cdh 5CreERT 2小鼠肺。实质拉伸和微血管扩张 单侧PNX后的灌注和剪切应力有助于PNX后肺生长。硅胶植入 替代切除肺叶的假体阻止了PNX后肺生长并降低了YAP 1/TAZ表达。 结扎右心叶肺动脉刺激了其余未闭塞叶的肺生长 离开PNX后我们推测，在PNX后代偿性肺生长过程中， 通过机械敏感的内皮YAP 1/TAZ信号传导。在目标1中，我们将通过以下方式研究该机制： 内皮YAP 1/TAZ在体外PNX后肺生长期间控制血管生成信号。在目标2中， 将确定内皮YAP 1/TAZ是否控制PNX后肺生长过程中的血管形成。 老鼠的肺在目标3中，我们将研究PNX改变的机械环境对血液的影响， 小鼠肺中的血管形成。我们的重点是新的机械敏感性机制的血管生成 在PNX后肺生长期间，新型小鼠肺凝胶植入系统是高度独特的， 创新的科学进步。如果这项研究证实内皮YAP 1/TAZ刺激血管生成， 小鼠肺PNX后，这项工作将进一步了解血管生成的机制，并导致 发展新的更好的器官再生策略。

Project Summary: Angiogenesis – the formation of new blood capillaries - plays a key role in organ regeneration. Thus, in order to regenerate adult organs, we need to understand the mechanisms of angiogenesis during organ regeneration. It has been reported that adult human lungs have potential to grow after unilateral pneumonectomy (PNX) and that inhibition of angiogenesis impairs post-PNX lung growth in adult mice. The overall goal of this proposal is to characterize the mechanism of angiogenesis during organ regeneration using lung as a model and leverage this knowledge to develop an efficient strategy for organ regeneration. Mechanosensitive transcriptional co- activators, Yes-associated protein (YAP1) and transcriptional co-activator with PDZ-binding motif (TAZ), stimulate angiogenesis and control organ size and regeneration. In the lung, YAP1 activation in alveolar stem cells promotes post-PNX lung growth. However, the role of endothelial YAP1/TAZ in angiogenesis during post- PNX lung growth remains unclear. Our preliminary data demonstrate that knockdown of YAP1 and/or TAZ decreases the expression of angiogenic factor receptor, Tie2, in endothelial cells (ECs) and inhibits EC sprouting. After unilateral PNX, the expression of YAP1/TAZ and Tie2 and vascular density increased in the remaining lung lobes. Compensatory lung growth after PNX was inhibited in VE-cadherin-specific Yap1 and/or Taz knockout (Yap1fl/fl-Cdh5CreERT2, Yap1iΔEC, Taz iΔEC, or Yap1/TaziΔEC) mice after tamoxifen-induced Yap1/Taz deletion. When we implanted fibrin gel on the control Yap1fl/fl mouse lung, ECs were recruited from host lungs and made vascular networks in the implanted gels, while vascular formation was attenuated in the gel implanted on the Yap1fl/fl-Cdh5CreERT2 mouse lungs. Parenchymal stretch and increases in microvascular perfusion and shear stress after unilateral PNX contribute to post-PNX lung growth. Insertion of silicone prosthesis to replace an excised lobe prevented post-PNX lung growth and decreased YAP1/TAZ expression. Ligation of right cardiac lobe pulmonary artery stimulated lung growth of the remaining non-occluded lobes after left PNX. We hypothesize that angiogenesis is stimulated during compensatory lung growth after PNX through mechanosensitive endothelial YAP1/TAZ signaling. In Aim 1, we will investigate the mechanism by which endothelial YAP1/TAZ control angiogenic signaling during post-PNX lung growth in vitro. In Aim 2, we will determine whether endothelial YAP1/TAZ control blood vessel formation during post-PNX lung growth in the mouse lung. In Aim 3, we will investigate the effects of mechanical environment altered by PNX on blood vessel formation in the mouse lung. Our focus on the new mechanosensitive mechanism of angiogenesis during post-PNX lung growth and the novel mouse lung gel implantation system are highly unique and innovative scientific advances. If this study validates that endothelial YAP1/TAZ stimulate angiogenesis in the mouse lungs after PNX, this work will further our understanding of the mechanism of angiogenesis and lead to the development of new and better strategies for organ regeneration.