Department of Orthodontics, University of Florida College of Dentistry, Gainesville, FL, 32610, USA.
Department of Oral Geriatrics, Hospital of Stomatology, Jilin University, Changchun, 130021, People's Republic of China.
Sci Rep. 2021 Apr 28;11(1):9214. doi: 10.1038/s41598-021-88665-y.
The (pro)renin receptor (PRR) is a multifunctional integral membrane protein that serves as a component of the vacuolar H-ATPase (V-ATPase) and also activates (pro)renin. We recently showed that full-length PRR, found as part of a V-ATPase sub-complex, is abundant in extracellular vesicles shed by osteoclasts. Here, we tested whether these extracellular vesicles stimulate (pro)renin. Extracellular vesicles isolated from the conditioned media of RAW 264.7 osteoclast-like cells or primary osteoclasts were characterized and counted by nanoparticle tracking. Immunoblotting confirmed that full-length PRR was present. Extracellular vesicles from osteoclasts dose-dependently stimulated (pro)renin activity, while extracellular vesicles from 4T1 cancer cells, in which we did not detect PRR, did not activate (pro)renin. To confirm that the ability of extracellular vesicles from osteoclasts to stimulate (pro)renin activity was due to the PRR, the "handle region peptide" from the PRR, a competitive inhibitor of PRR activity, was tested. It dose-dependently blocked the ability of extracellular vesicles to stimulate the enzymatic activity of (pro)renin. In summary, the PRR, an abundant component of extracellular vesicles shed by osteoclasts, stimulates (pro)renin activity. This represents a novel mechanism by which extracellular vesicles can function in intercellular regulation, with direct implications for bone biology.
（前）肾素受体（PRR）是一种多功能的整合膜蛋白，作为液泡型 H+-ATP 酶（V-ATPase）的组成部分，并激活（前）肾素。我们最近发现，全长 PRR 作为 V-ATPase 亚复合物的一部分，在破骨细胞释放的细胞外囊泡中大量存在。在这里，我们测试了这些细胞外囊泡是否能刺激（前）肾素。通过纳米颗粒跟踪法对从 RAW 264.7 破骨细胞样细胞或原代破骨细胞的条件培养基中分离的细胞外囊泡进行了表征和计数。免疫印迹证实了全长 PRR 的存在。破骨细胞来源的细胞外囊泡以剂量依赖性方式刺激（前）肾素活性，而在我们未检测到 PRR 的 4T1 癌细胞来源的细胞外囊泡则不能激活（前）肾素。为了证实破骨细胞来源的细胞外囊泡刺激（前）肾素活性的能力归因于 PRR，我们测试了 PRR 的“手柄区肽”，这是 PRR 活性的竞争性抑制剂。它以剂量依赖性方式阻断了细胞外囊泡刺激（前）肾素酶活性的能力。总之，破骨细胞释放的细胞外囊泡中的 PRR 是一种丰富的成分，它能刺激（前）肾素的活性。这代表了细胞外囊泡在细胞间调节中发挥作用的一种新机制，对骨生物学具有直接影响。
