RESUMO
The recruitment of pericytes and vascular smooth muscle cells (SMCs) that enwrap endothelial cells (ECs) is a crucial process for vascular maturation and stabilization. Communication between these two cell types is crucial during vascular development and in maintaining vessel homeostasis. Extracellular vesicles (EVs) have emerged as a new communication tool involving the exchange of microRNAs between cells. In the present study, we searched for microRNAs that could be transferred via EVs from ECs to SMCs and vice versa. Thanks to a microRNA profiling experiment, we found that two microRNAs are more exported in each cell type in coculture experiments: while miR-539 is more secreted by ECs, miR-582 is more present in EVs from SMCs. Functional assays revealed that both microRNAs can modulate both cell-type phenotypes. We further identified miR-539 and miR-582 targets, in agreement with their respective cell functions. The results obtained in vivo in the neovascularization model suggest that miR-539 and miR-582 might cooperate to trigger the process of blood vessel coverage by smooth muscle cells in a mature plexus. Taken together, these results are the first to highlight the role of miR-539 and miR-582 in angiogenesis and communication between ECs and SMCs.
Assuntos
Comunicação Celular , Vesículas Extracelulares/metabolismo , Células Endoteliais da Veia Umbilical Humana/citologia , Músculo Liso Vascular/citologia , Miócitos de Músculo Liso/citologia , Vasos Sanguíneos/metabolismo , Técnicas de Cocultura , Vesículas Extracelulares/ultraestrutura , Regulação da Expressão Gênica , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Modelos Biológicos , Neovascularização Fisiológica/genética , Remodelação VascularRESUMO
In endothelial cells, binding of vascular endothelial growth factor (VEGF) to the receptor VEGFR2 activates multiple signaling pathways that trigger processes such as proliferation, survival, and migration that are necessary for angiogenesis. VEGF-bound VEGFR2 becomes internalized, which is a key step in the proangiogenic signal. We showed that the urokinase plasminogen activator receptor (uPAR) interacted with VEGFR2 and described the mechanism by which this interaction mediated VEGF signaling and promoted angiogenesis. Knockdown of uPAR in human umbilical vein endothelial cells (HUVECs) impaired VEGFR2 signaling, and uPAR deficiency in mice prevented VEGF-induced angiogenesis. Upon exposure of HUVECs to VEGF, uPAR recruited the low-density lipoprotein receptor-related protein 1 (LRP-1) to VEGFR2, which induced VEGFR2 internalization. Thus, the uPAR-VEGFR2 interaction is crucial for VEGF signaling in endothelial cells.
Assuntos
Neovascularização Fisiológica/fisiologia , Receptores de Ativador de Plasminogênio Tipo Uroquinase/metabolismo , Fator A de Crescimento do Endotélio Vascular/fisiologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Animais , Endocitose , Células Endoteliais da Veia Umbilical Humana , Humanos , Integrina beta1/metabolismo , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Camundongos , Ligação Proteica , Transdução de SinaisRESUMO
The N-terminal fragment of prolactin (16K PRL) inhibits tumor growth by impairing angiogenesis, but the underlying mechanisms are unknown. Here, we found that 16K PRL binds the fibrinolytic inhibitor plasminogen activator inhibitor-1 (PAI-1), which is known to contextually promote tumor angiogenesis and growth. Loss of PAI-1 abrogated the antitumoral and antiangiogenic effects of 16K PRL. PAI-1 bound the ternary complex PAI-1-urokinase-type plasminogen activator (uPA)-uPA receptor (uPAR), thereby exerting antiangiogenic effects. By inhibiting the antifibrinolytic activity of PAI-1, 16K PRL also protected mice against thromboembolism and promoted arterial clot lysis. Thus, by signaling through the PAI-1-uPA-uPAR complex, 16K PRL impairs tumor vascularization and growth and, by inhibiting the antifibrinolytic activity of PAI-1, promotes thrombolysis.