Frazer Institute, The University of Queensland, Dermatology Research Centre, Experimental Dermatology Group, Brisbane, QLD, 4102, Australia.
Mater Research, Translational Research Institute, Macrophage Biology Laboratory, Brisbane, QLD, 4102, Australia.
Angiogenesis. 2024 Aug;27(3):545-560. doi: 10.1007/s10456-024-09927-7. Epub 2024 May 11.
Regenerative capabilities of the endothelium rely on vessel-resident progenitors termed endothelial colony forming cells (ECFCs). This study aimed to investigate if these progenitors are impacted by conditions (i.e., obesity or atherosclerosis) characterized by increased serum levels of oxidized low-density lipoprotein (oxLDL), a known inducer of Endothelial-to-Mesenchymal Transition (EndMT). Our investigation focused on understanding the effects of EndMT on the self-renewal capabilities of progenitors and the associated molecular alterations. In the presence of oxLDL, ECFCs displayed classical features of EndMT, through reduced endothelial gene and protein expression, function as well as increased mesenchymal genes, contractility, and motility. Additionally, ECFCs displayed a dramatic loss in self-renewal capacity in the presence of oxLDL. RNA-sequencing analysis of ECFCs exposed to oxLDL validated gene expression changes suggesting EndMT and identified SOX9 as one of the highly differentially expressed genes. ATAC sequencing analysis identified SOX9 binding sites associated with regions of dynamic chromosome accessibility resulting from oxLDL exposure, further pointing to its importance. EndMT phenotype and gene expression changes induced by oxLDL in vitro or high fat diet (HFD) in vivo were reversed by the silencing of SOX9 in ECFCs or the endothelial-specific conditional knockout of Sox9 in murine models. Overall, our findings support that EndMT affects vessel-resident endothelial progenitor's self-renewal. SOX9 activation is an early transcriptional event that drives the mesenchymal transition of endothelial progenitor cells. The identification of the molecular network driving EndMT in vessel-resident endothelial progenitors presents a new avenue in understanding and preventing a range of condition where this process is involved.
内皮细胞的再生能力依赖于称为内皮祖细胞的血管驻留前体细胞。本研究旨在探讨这些前体细胞是否受到血清中氧化型低密度脂蛋白（oxLDL）水平升高的影响，oxLDL 是已知的内皮细胞向间充质转化（EndMT）的诱导物。我们的研究重点是了解 EndMT 对祖细胞自我更新能力的影响及其相关的分子改变。在 oxLDL 的存在下，ECFCs 通过减少内皮基因和蛋白的表达、功能以及增加间充质基因、收缩性和迁移性，表现出典型的 EndMT 特征。此外，ECFCs 在 oxLDL 的存在下表现出自我更新能力的急剧丧失。对暴露于 oxLDL 的 ECFCs 进行 RNA 测序分析验证了基因表达的变化，提示 EndMT，并鉴定 SOX9 为高度差异表达基因之一。ATAC 测序分析鉴定了 SOX9 结合位点，这些结合位点与 oxLDL 暴露导致的染色体可及性动态区域相关，进一步表明其重要性。SOX9 在 ECFCs 中的沉默或 Sox9 在小鼠模型中的内皮特异性条件性敲除可逆转 oxLDL 在体外或高脂肪饮食（HFD）体内诱导的 EndMT 表型和基因表达变化。总的来说，我们的研究结果支持 EndMT 影响血管驻留内皮祖细胞的自我更新。SOX9 的激活是驱动内皮祖细胞向间充质转化的早期转录事件。鉴定驱动血管驻留内皮祖细胞中 EndMT 的分子网络为理解和预防涉及该过程的一系列疾病提供了新途径。
