Wang Zhi, Yu Daozhan, Wang Mengqiao, Wang Qilong, Kouznetsova Jennifer, Yang Rongze, Qian Kun, Wu Wenjun, Shuldiner Alan, Sztalryd Carole, Zou Minghui, Zheng Wei, Gong Da-Wei
1] Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201 [2] Department of Cardiology, Nanjing Chest Hospital, Southeast University School of Medicine, Nanjing, 210029.
Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201.
Sci Rep. 2015 Feb 2;5:8170. doi: 10.1038/srep08170.
Elabela (ELA) or Toddler is a recently discovered hormone which is required for normal development of heart and vasculature through activation of apelin receptor (APJ), a G protein-coupled receptor (GPCR), in zebrafish. The present study explores whether the ELA-APJ signaling pathway is functional in the mammalian system. Using reverse-transcription PCR, we found that ELA is restrictedly expressed in human pluripotent stem cells and adult kidney whereas APJ is more widely expressed. We next studied ELA-APJ signaling pathway in reconstituted mammalian cell systems. Addition of ELA to HEK293 cells over-expressing GFP-AJP fusion protein resulted in rapid internalization of the fusion receptor. In Chinese hamster ovarian (CHO) cells over-expressing human APJ, ELA suppresses cAMP production with EC50 of 11.1 nM, stimulates ERK1/2 phosphorylation with EC50 of 14.3 nM and weakly induces intracellular calcium mobilization. Finally, we tested ELA biological function in human umbilical vascular endothelial cells and showed that ELA induces angiogenesis and relaxes mouse aortic blood vessel in a dose-dependent manner through a mechanism different from apelin. Collectively, we demonstrate that the ELA-AJP signaling pathways are functional in mammalian systems, indicating that ELA likely serves as a hormone regulating the circulation system in adulthood as well as in embryonic development.
埃拉贝拉（ELA）或托德林蛋白是一种最近发现的激素，在斑马鱼中，它通过激活阿佩林受体（APJ，一种G蛋白偶联受体（GPCR））来促进心脏和血管的正常发育。本研究探讨了ELA-APJ信号通路在哺乳动物系统中是否发挥作用。通过逆转录PCR，我们发现ELA在人类多能干细胞和成年肾脏中呈限制性表达，而APJ的表达更为广泛。接下来，我们在重组哺乳动物细胞系统中研究了ELA-APJ信号通路。将ELA添加到过表达绿色荧光蛋白-APJ融合蛋白的HEK293细胞中，导致融合受体迅速内化。在过表达人类APJ的中国仓鼠卵巢（CHO）细胞中，ELA抑制cAMP生成，半数有效浓度（EC50）为11.1 nM，刺激细胞外信号调节激酶1/2（ERK1/2）磷酸化，EC50为14.3 nM，并微弱诱导细胞内钙动员。最后，我们在人脐静脉内皮细胞中测试了ELA的生物学功能，结果表明ELA通过一种不同于阿佩林的机制，以剂量依赖的方式诱导血管生成并使小鼠主动脉血管舒张。总的来说，我们证明了ELA-APJ信号通路在哺乳动物系统中发挥作用，这表明ELA可能在成年期以及胚胎发育过程中作为一种调节循环系统的激素。
