Abstract 13494: Lncrna Khps1 Regulates Hif-1a-dependent Pulmonary Vascular Remodeling by Targeting Mir-1, Sphk1 and S1pr2

Abstract

Rationale: Pulmonary vascular remodeling is common in pulmonary arterial hypertension (PAH) and is associated with increased risk of right ventricular failure and death. We have previously reported that sphingosine kinase 1 (Sphk1), sphingosine 1 phosphate receptor 2 (S1PR2), microRNA-1-3p (miR-1-3p) and hypoxia-inducible factor-1α (HIF-1α) are involved in the regulation of pulmonary vascular remodeling and the development of PAH. Recently, it has been reported that the long noncoding RNA (LncRNA) Khps1 is required for Sphk1 expression and cell proliferation. However, whether Khps1 plays a role in PAH is unclear. Here, we tested the hypothesis that Khps1 has an impact on pulmonary vascular remodeling in PAH by regulating Sphk1/S1PR2/HIF-1α signaling pathway. Methods and Results: Using qRT-PCR, our data showed that Khps1 expression levels were up-regulated in pulmonary artery smooth muscle cells (PASMCs) from PAH patients. Increased Khps1 expression levels were also observed in human PASMCs exposed to hypoxia and in lungs obtained from monocrotaline (MCT)-treated rats or hypoxia exposed mice. Luciferase reporter assays showed that Khps1 expression is dependent on E2F1-mediated promoter activation. In silico analysis and luciferase reporter assays also suggested that Khps1 can directly bind to miR-1-3p, suggesting that Khps1 functions as a competing endogenous RNA. Similar studies also showed that miR-1-3p regulates expression of Sphk1 and S1PR2 by binding to their 3’UTR regions. Concurrent E2F1 overexpression and khps1 silencing resulted in a decrease in Sphk1 and S1PR2 expression levels, reduced HIF-1α stabilization and suppressed PASMCs proliferation. Finally, over expression of Sphk1 increased HIF-1α and that in turn increased E2F1 expression in human PASMCs. Conclusion: These data reveal a novel regulatory loop between E2F1, Khps1, miR-1-3p and Sphk1/S1PR2 in the regulation of PASMC proliferation and pulmonary vascular remodeling in PAH. These data also suggest Khps1 regulates pulmonary vascular remodeling in a HIF-1α-dependent manner through targeting Sphk1 and S1PR2.