Transcriptional regulation of fibroblast generation in the embryonic mouse heart.

小鼠胚胎心脏成纤维细胞生成的转录调控。

• 批准号: RGPIN-2019-06658
• 负责人: Wigle, Jeffrey
• 金额: $ 2.33万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715728
• 关键词: Transcriptional; regulation; fibroblast; generation; embryonic

During embryonic development, epithelial cells, such as those that cover the growing heart (epicardium), undergo a process termed Epithelial to Mesenchymal Transition (EMT) and convert into mesenchymal progenitors, which give rise to the fibroblast, endothelial and vascular smooth muscle cell populations of the developing heart. Cardiac fibroblasts can also be generated by a variation of the EMT program in endothelial cells termed Endothelial to Mesenchymal Transition (EndMT), which is important for cardiac valve morphogenesis. A key regulator of EMT and EndMT is the cytokine Transforming Growth Factor- (TGF-). The Mesenchyme Homeobox 2 (MEOX2) transcription factor blocks TGF- mediated EMT. Our previous work has demonstrated that MEOX2 inhibits endothelial cell proliferation and promotes endothelial senescence. In contrast to MEOX2, the Zinc Finger E Box-Binding Homeobox 2 protein (ZEB2) is activated by TGF- treatment and ZEB2 represses the expression of Meox2 and epithelial markers such as E-Cadherin. Whether the ZEB2/MEOX2 transcriptional switch is required for embryonic cardiac fibroblast development is not known. The overall goal of my research program is to identify the transcription factor networks that are required for cardiac fibroblast differentiation during embryonic development. My goals for the next 5 years are to: Goal 1. Examine the role of the ZEB2/MEOX2 pathway in the generation of embryonic cardiac fibroblasts both in vitro and in vivo. We will use both gain and loss of function approaches to test the roles of these transcriptional switches during mesenchymal transition of cardiac cells (epicardial and endothelial) into fibroblasts. To build on our in vitro studies of the ZEB2/MEOX2 switch, we will use transgenic mouse approaches to specifically delete these genes in cardiac endothelial cells and the cardiac epicardium. Goal 2. Identify enhancer elements that control cell type specific expression of Zeb2 and Meox2. The genomic regulatory elements that control expression of these two regulatory genes during embryonic development are not known. By identifying and validating the enhancer elements required to regulate the expression of Meox2 and Zeb2, we will be able to establish the transcription factor network that controls the development of cardiac fibroblasts. Together, these studies conducted by my HQP (2 PhD students and 1 MSc student) will delineate how ZEB2/MEOX2 control embryonic fibroblast generation. This research program will characterize a novel mechanism that controls an important pathway in embryonic development of the mammalian cardiovascular system. Through these studies, my HQP will acquire skills in laboratory research (experimental design, conducting experiments, analyzing results) as well as skills in disseminating their findings (manuscript writing and presenting talks) that will enable them to succeed in in a wide range of future careers.

在胚胎发育过程中，上皮细胞，如覆盖在生长中的心脏（心外膜）上的上皮细胞，经历一个称为上皮向间充质转化（EMT）的过程，并转化为间充质祖细胞，从而产生成纤维细胞、内皮细胞和血管平滑肌细胞群。心脏成纤维细胞也可以通过内皮细胞向间充质转化（EndMT）的EMT程序的变异产生，这对心脏瓣膜的形态发生很重要。EMT和EndMT的关键调节因子是细胞因子转化生长因子- (TGF-)。Mesenchyme Homeobox 2 （MEOX2）转录因子阻断TGF-介导的EMT。我们之前的研究表明，MEOX2抑制内皮细胞增殖，促进内皮细胞衰老。与MEOX2相反，锌指E Box-Binding Homeobox 2蛋白（ZEB2）被TGF-激活，ZEB2抑制MEOX2和上皮标志物如E- cadherin的表达。胚胎心脏成纤维细胞发育是否需要ZEB2/MEOX2转录开关尚不清楚。