AUTHOR=Sugimoto Koichi , Yokokawa Tetsuro , Misaka Tomofumi , Kaneshiro Takashi , Yamada Shinya , Yoshihisa Akiomi , Nakazato Kazuhiko , Takeishi Yasuchika 

TITLE=Endothelin-1 Upregulates Activin Receptor-Like Kinase-1 Expression via Gi/RhoA/Sp-1/Rho Kinase Pathways in Human Pulmonary Arterial Endothelial Cells

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2021.648981

DOI=10.3389/fcvm.2021.648981

ISSN=2297-055X

ABSTRACT=<p><bold>Background:</bold> Pulmonary arterial hypertension (PAH) is characterized by pulmonary vasoconstriction and organic stenosis. It has been demonstrated that endothelin-1 (ET-1) induces pulmonary vasoconstriction through the activation of RhoA. In addition, a gene mutation of activin receptor-like kinase (ACVRL)-1 is recognized in PAH patients. However, little is known about the association between ET-1 and ACVRL-1.</p><p><bold>Objective:</bold> In the present study, we aimed to investigate the effect of ET-1 on ACVRL-1 expression and delineate the involvement of the G<italic>i</italic>/RhoA/Rho kinase pathway.</p><p><bold>Methods:</bold> ET-1 was added to culture medium of human pulmonary arterial endothelial cells (PAECs). Pre-treatment with pertussis toxin (PTX) or exoenzyme C3 transferase (C3T) was performed for inhibition of G<italic>i</italic> or RhoA, respectively. Rho kinase was inhibited by Y27632. Mithramycin A was used for inhibition of Sp-1, which is a transcriptional factor of ACVRL-1. The active form of RhoA (GTP-RhoA) was assessed by pull-down assay.</p><p><bold>Results:</bold> ACVRL-1 expression was increased by ET-1 in the PAECs. Pull-down assay revealed that ET-1 induced GTP-loading of RhoA, which was suppressed by pre-treatment with PTX or C3T. Further, PTX, C3T, and Y27632 suppressed the ET-1-induced ACVRL-1 expression. ET-1 increased the activity of the ACVRL-1 promoter and stabilized the ACVRL-1 mRNA. Sp-1 peaked 15 min after adding ET-1 to the PAECs. PTX and C3T prevented the increase of Sp-1 induced by ET-1. Inhibition of Sp-1 by mithramycin A suppressed ET-1-induced ACVRL-1 upregulation.</p><p><bold>Conclusion:</bold> The present study demonstrated that ET-1 increases ACVRL-1 expression in human PAECs <italic>via</italic> the G<italic>i</italic>/RhoA/Rho kinase pathway with the involvement of Sp-1.</p>