Department of Pharmaceutical Sciences, College of Health Professions, North Dakota State University, Fargo, North Dakota.
J Cell Physiol. 2019 Nov;234(11):20420-20431. doi: 10.1002/jcp.28643. Epub 2019 Apr 15.
CD34 hematopoietic stem/progenitor cells (HSPCs) are vasculogenic and hypoxia is a strong stimulus for the vasoreparative functions of these cells. Angiotensin-converting enzyme 2 (ACE2)/angiotensin-(1-7)/Mas receptor (MasR) pathway stimulates vasoprotective functions of CD34 cells. This study tested if ACE2 and MasR are involved in the hypoxic stimulation of CD34 cells. Cells were isolated from circulating mononuclear cells derived from healthy subjects (n = 46) and were exposed to normoxia (20% O ) or hypoxia (1% O ). Luciferase reporter assays were carried out in cells transduced with lentivirus carrying ACE2- or MasR- or a scramble-3'-untranslated region gene with a firefly luciferase reporter. Expressions or activities of ACE, angiotensin receptor Type 1 (AT1R), ACE2, and MasR were determined. In vitro observations were verified in HSPCs derived from mice undergoing hindlimb ischemia (HLI). In vitro exposure to hypoxia-increased proliferation and migration of CD34 cells in basal conditions or in response to vascular endothelial growth factor (VEGF) or stromal-derived factor 1α (SDF) compared with normoxia. Expression of ACE2 or MasR was increased relative to normoxia while ACE or AT1R expressions were unaltered. Luciferase activity was increased by hypoxia in cells transfected with the luciferase reporter plasmids coding for the ACE2- or MasR promoters relatively to the control. The effects of hypoxia were mimicked by VEGF or SDF under normoxia. Hypoxia-induced ADAM17-dependent shedding of functional ACE2 fragments. In mice undergoing HLI, increased expression/activity of ACE2 and MasR were observed in the circulating HSPCs. This study provides compelling evidence for the hypoxic upregulation of ACE2 and MasR in CD34 cells, which likely contributes to vascular repair.
CD34 造血干/祖细胞 (HSPCs) 具有血管生成能力，而缺氧是这些细胞血管修复功能的强烈刺激因素。血管紧张素转换酶 2 (ACE2)/血管紧张素-(1-7)/Mas 受体 (MasR) 途径刺激 CD34 细胞的血管保护功能。本研究检测了 ACE2 和 MasR 是否参与 CD34 细胞的低氧刺激。细胞从健康受试者的循环单核细胞中分离出来（n=46），并暴露于常氧（20% O ）或缺氧（1% O ）条件下。用携带 ACE2 或 MasR 或乱序 3'-非翻译区基因的慢病毒转导细胞，进行荧光素酶报告基因检测。测定 ACE、血管紧张素受体 1 (AT1R)、ACE2 和 MasR 的表达或活性。在经历后肢缺血（HLI）的小鼠的 HSPCs 中验证了体外观察结果。与常氧相比，缺氧体外暴露增加了基础条件下或对血管内皮生长因子 (VEGF) 或基质衍生因子 1α (SDF) 反应的 CD34 细胞的增殖和迁移。ACE2 或 MasR 的表达相对于常氧增加，而 ACE 或 AT1R 的表达没有改变。与对照相比，用编码 ACE2 或 MasR 启动子的荧光素酶报告质粒转染的细胞中，荧光素酶活性在低氧条件下增加。在常氧条件下，VEGF 或 SDF 模拟了低氧的作用。缺氧诱导的 ADAM17 依赖性功能性 ACE2 片段脱落。在经历 HLI 的小鼠中，循环 HSPCs 中观察到 ACE2 和 MasR 的表达/活性增加。本研究为 CD34 细胞中 ACE2 和 MasR 的低氧上调提供了有力证据，这可能有助于血管修复。
