New roles of endothelial regrowth in ischemic tissue recovery and regeneration

项目摘要 组织再生和修复对于维持生理稳态是必不可少的，并且依赖于精确的组织修复。 控制调节脉管系统或由脉管系统调节的分子网络。存在内皮细胞（EC） 在血管和淋巴管中（即，BEC和LEC分别）是血管- 修复受损组织的依赖过程，因为它们控制着旁分泌因子的分泌， 包括血管本身和附近的细胞。然而，EC管理活动的机制 参与损伤组织恢复的其它细胞成分还没有被充分地 表征了我们实验室的长期目标是阐明调节血液的基本过程， 血管功能，并了解这些机制的破坏如何导致病理性血管 缺陷我们以前已经证明，在小鼠中，Foxc 1和/或Foxc 2的全纯合敲除突变， 与血管异常有关;然而，突变也会导致胚胎或围产期死亡， 试图确定这两个Foxc基因在成年动物中如何发挥作用的尝试通常是不确定的。到 为了克服这一局限性，我们建立了一个小鼠系，其携带他莫昔芬可诱导的，内皮细胞（EC）特异性的， 复合Foxc 1; Foxc 2突变（即，EC-Foxc-DKO小鼠），以及来自初步研究的结果 表明这些突变损害了缺血后小肠的再生- 再灌注（I/R）损伤通过引起（1）肠血液和淋巴管的再生长，（2） 上皮下基质细胞的形成（例如，（3）CXCL 12和R-spondin 3在细胞中的表达。 （4）肠干细胞中Wnt/β-catenin通路的激活 （ISCs）。已知CXCL 12调节血管生成，而R-spondin 3保护小鼠免受血管渗漏， 这两个因子协同刺激经典Wnt/β-catenin信号传导，随后调节 ISCs的扩散。因此，我们的中心假设是Foxc 1/c2在BEC中的转录活性， LEC通过调节CXCL 12和R-spondin 3信号通路促进血管修复和肠再生。 我们将通过以下两个具体目标来检验我们的中心假设：（1）确定Foxc 1和Foxc 2是否 在肠损伤恢复期间，肠血管修复需要（2）确定 Foxc 1和Foxc 2调节血管恢复和肠再生的机制，以及（3） 确定Foxc 1和Foxc 2是否调节淋巴管恢复和肠再生。总的来说， 本提案中描述的实验将提供关于Foxc 1/c2表达如何在 血管内皮细胞有助于肠修复和再生。此外，由于血管缺陷 有助于各种缺血性疾病，我们的研究结果可能对其他缺血性疾病有重要意义。 与组织再生障碍相关的疾病，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.