Si Yameng, Huang Jiadong, Li Xiang, Fu Yu, Xu Rongyao, Du Yifei, Cheng Jie, Jiang Hongbing
Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 136 Hanzhong Road, Nanjing, 210029, Jiangsu Province, China.
The Affiliated Stomatological Hospital of Xuzhou Medical University, Xuzhou, China.
Cell Commun Signal. 2020 Aug 31;18(1):139. doi: 10.1186/s12964-020-00606-w.
Venous malformations (VMs), most of which associated with activating mutations in the endothelial cells (ECs) tyrosine kinase receptor TIE2, are characterized by dilated and immature veins with scarce smooth muscle cells (SMCs) coverage. However, the underlying mechanism of interaction between ECs and SMCs responsible for VMs has not been fully understood.
Here, we screened 5 patients with TIE2-L914F mutation who were diagnosed with VMs by SNP sequencing, and we compared the expression of platelet-derived growth factor beta (PDGFB) and α-SMA in TIE2 mutant veins and normal veins by immunohistochemistry. In vitro, we generated TIE2-L914F-expressing human umbilical vein endothelial cells (HUVECs) and performed BrdU, CCK-8, transwell and tube formation experiments on none-transfected and transfected ECs. Then we investigated the effects of rapamycin (RAPA) on cellular characteristics. Next we established a co-culture system and investigated the role of AKT/FOXO1/PDGFB in regulating cross-talking of mutant ECs and SMCs.
VMs with TIE2-L914F mutation showed lower expression of PDGFB and α-SMA than normal veins. TIE2 mutant ECs revealed enhanced cell viability and motility, and decreased tube formation, whereas these phenotypes could be reversed by rapamycin. Mechanically, RAPA ameliorated the physiological function of mutant ECs by inhibiting AKT-mTOR pathway, but also facilitated the nuclear location of FOXO1 and the expression of PDGFB in mutant ECs, and then improved paracrine interactions between ECs and SMCs. Moreover, TIE2 mutant ECs strongly accelerated the transition of SMCs from contractile phenotype to synthetic phenotype, whereas RAPA could prevent the phenotype transition of SMCs.
Our data demonstrate a previously unknown mechanistic linkage of AKT-mTOR/FOXO1 pathway between mutant ECs and SMCs in modulating venous dysmorphogenesis, and AKT/FOXO1 axis might be a potential therapeutic target for the recovery of TIE2-mutation causing VMs. Video Abstract.
静脉畸形（VMs）大多与内皮细胞（ECs）酪氨酸激酶受体TIE2的激活突变相关，其特征为扩张且不成熟的静脉，平滑肌细胞（SMCs）覆盖稀少。然而，导致静脉畸形的内皮细胞与平滑肌细胞之间相互作用的潜在机制尚未完全明确。
在此，我们筛选了5例经单核苷酸多态性测序诊断为静脉畸形且携带TIE2-L914F突变的患者，并通过免疫组化比较了TIE2突变静脉和正常静脉中血小板衍生生长因子β（PDGFB）和α-平滑肌肌动蛋白（α-SMA）的表达。在体外，我们构建了表达TIE2-L914F的人脐静脉内皮细胞（HUVECs），并对未转染和转染的内皮细胞进行了BrdU、CCK-8、Transwell和管腔形成实验。然后我们研究了雷帕霉素（RAPA）对细胞特性的影响。接下来我们建立了共培养体系，并研究了AKT/FOXO1/PDGFB在调节突变内皮细胞与平滑肌细胞相互作用中的作用。
携带TIE2-L914F突变的静脉畸形中PDGFB和α-SMA的表达低于正常静脉。TIE2突变的内皮细胞显示出细胞活力和迁移能力增强，管腔形成减少，而这些表型可被雷帕霉素逆转。机制上，RAPA通过抑制AKT-mTOR途径改善了突变内皮细胞的生理功能，但也促进了FOXO1的核定位以及突变内皮细胞中PDGFB的表达，进而改善了内皮细胞与平滑肌细胞之间的旁分泌相互作用。此外，TIE2突变的内皮细胞强烈加速了平滑肌细胞从收缩表型向合成表型的转变，而RAPA可防止平滑肌细胞的表型转变。
我们的数据证明了突变内皮细胞与平滑肌细胞之间在调节静脉发育异常过程中AKT-mTOR/FOXO1途径存在先前未知的机制联系，并且AKT/FOXO1轴可能是恢复由TIE2突变引起的静脉畸形的潜在治疗靶点。视频摘要。
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