New roles of endothelial regrowth in ischemic tissue recovery and regeneration

项目摘要 组织的再生和修复对于维持生理动态平衡是必不可少的，并依赖于 对调节维管系统或受其调节的分子网络的控制。内皮细胞(ECs)存在 在血管和淋巴管中(分别是BECs和LECs)是血管的关键参与者。 修复受损组织的依赖过程，因为它们控制旁分泌因子的分泌 无论是血管本身还是附近的细胞。然而，欧洲共同体管理经济活动的机制 参与损伤组织恢复的其他细胞成分尚未充分 特色化的。我们实验室的长期目标是阐明调节血液和 淋巴管功能和了解这些机制的破坏如何导致病理性血管 缺陷。我们之前已经证明，在小鼠中，Foxc1和/或FOXC2的全局纯合敲除突变 与血管异常有关；然而，这些突变也会导致胚胎或围产期死亡，因此 试图确定这两个foxc基因在成年动物中是如何发挥作用的，通常都没有定论。至 克服了这一限制，我们产生了一系列携带他莫昔芬诱导的、内皮细胞(EC)特异性的 化合物Foxc1；FOXC2突变(即EC-Foxc-DKO小鼠)和初步调查结果 这些动物表明，这些突变损害了缺血后小肠的再生- 再灌注(I/R)损伤引起的缺陷：(1)肠血和淋巴管的再生，(2) 上皮下基质细胞(如端粒细胞)的形成，(3)CXCL12和R-Spindin3的表达。 肠BECs和LECs；(4)肠干细胞中Wnt/β-catenin通路的激活 (ISCS)。已知CXCL12调节血管生成，而R-Spindin3保护小鼠免受血管渗漏，以及 这两个因素协同刺激规范的Wnt/β-连环蛋白信号，随后调节 ISCs的增殖。因此，我们的中心假设是BEC中Foxc1/c2的转录活性 LECs通过调节CXCL12和R-Spindin3信号，促进血管修复和肠道再生。 我们将通过追求两个具体目标来验证我们的中心假设：(1)确定FOXc1和FOXC2 是肠道损伤恢复过程中修复肠道血管系统所必需的，(2)确定 Foxc1和FOXC2调节血管恢复和肠道再生的机制，以及(3) 确定FOXc1和FOXC2是否调节淋巴管恢复和肠道再生。总而言之， 这项提案中描述的实验将提供关于Foxc1/c2如何在 血管内皮细胞有助于肠道修复和再生。此外，由于血管缺陷 导致多种缺血性疾病，我们的研究结果可能对其他缺血性疾病有重要意义 与组织再生障碍有关的疾病，如心血管疾病。

Project Summary Tissue regeneration and repair is essential for maintaining physiological homeostasis and relies on the precise control of molecular networks that regulate, or are regulated by, the vasculature. Endothelial cells (ECs) present in the blood and lymphatic vessels (i.e., BECs and LECs, respectively) are crucial participants in the vascular- dependent processes that restore damaged tissue, because they control the secretion of paracrine factors from both the vessels themselves and nearby cells. However, the mechanisms by which ECs govern the activity of other cellular components that participate in the recovery of injured tissues have yet to be adequately characterized. The long-term goal of our lab is to elucidate the fundamental processes that regulate blood- and lymphatic-vessel function and to understand how disruption of these mechanisms leads to pathological vascular defects. We have previously shown that in mice, global homozygous knockout mutations of Foxc1 and/or Foxc2 are associated with vascular anomalies; however, the mutations also lead to embryonic or perinatal lethality, so attempts to determine how the two Foxc genes function in adult animals have generally been inconclusive. To overcome this limitation, we generated a line of mice carrying tamoxifen-inducible, endothelial cell (EC)-specific, compound Foxc1;Foxc2 mutations (i.e., EC-Foxc-DKO mice), and the results from preliminary investigations with these animals indicate that the mutations impair regeneration of the small intestine after ischemia- reperfusion (I/R) injury by causing defects in (1) the regrowth of intestinal blood and lymphatic vessels, (2) the formation of subepithelial stromal cells (e.g., telocytes), (3) the expression of CXCL12 and R-spondin3 in intestinal BECs and LECs, respectively and (4) activation of the Wnt/β-catenin pathway in intestinal stem cells (ISCs). CXCL12 is known to regulate angiogenesis, while R-spondin3 protects mice from vascular leakage, and the two factors cooperatively stimulate canonical Wnt/β-catenin signaling, which subsequently regulates the proliferation of ISCs. Thus, our central hypothesis is that the transcriptional activity of Foxc1/c2 in BECs and LECs contributes to vascular repair and intestinal regeneration by regulating CXCL12 and R-spondin3 signaling. We will test our central hypothesis by pursuing the two Specific Aims: (1) To determine whether Foxc1 and Foxc2 are required for repair of the intestinal vasculature during recovery from intestinal injury, (2) To determine the mechanisms by which Foxc1 and Foxc2 regulate blood vessel recovery and intestinal regeneration, and (3) To determine whether Foxc1 and Foxc2 regulate lymphatic vessel recovery and intestinal regeneration. In summary, the experiments described in this proposal will provide crucial information about how Foxc1/c2 expression in vascular ECs contributes to intestinal repair and regeneration. Furthermore, since vascular deficiencies contribute to a variety of ischemic disorders, our findings may have important implications for other ischemic conditions that are associated with impairments in tissue regeneration, such as cardiovascular disease.