title: Transforming growth factor-β-sphingosine kinase 1/S1P signaling upregulates microRNA-21 to promote fibrosis in renal tubular epithelial cells.
abstract: Renal fibrosis is a progressive pathological change characterized by tubular cell apoptosis, tubulointerstitial fibroblast proliferation, and excessive deposition of extracellular matrix (ECM). miR-21 has been implicated in transforming growth factor-β (TGF-β)-stimulated tissue fibrosis. Recent studies showed that sphingosine kinase/sphingosine-1-phosphate (SphK/S1P) are also critical for TGF-β-stimulated tissue fibrosis; however, it is not clear whether SphK/S1P interacts with miR-21 or not. In this study, we hypothesized that SphK/S1P signaling is linked to upregulation of miR-21 by TGF-β. To verify this hypothesis, we first determined that miR-21 was highly expressed in renal tubular epithelial cells (TECs) stimulated with TGF-β by using qRT-PCR and Northern blotting. Simultaneously, inhibition of miR-21, mediated by the corresponding antimir, markedly decreased the expression and deposition of type I collagen, fibronectin (Fn), cysteine-rich protein 61 (CCN1), α-smooth muscle actin, and fibroblast-specific protein1 in TGF-β-treated TECs. ELISA and qRT-PCR were used to measure the S1P and SphK1 levels in TECs. S1P production was induced by TGF-β through activation of SphK1. Furthermore, it was observed that TGF-β-stimulated upregulation of miR-21 was abolished by SphK1 siRNA and was restored by the addition of exogenous S1P. Blocking S1PR2 also inhibited upregulation of miR-21. Additionally, miR-21 overexpression attenuated the repression of TGF-β-stimulated ECM deposition and epithelial-mesenchymal transition by SphK1 and S1PR2 siRNA. In summary, our study demonstrates a link between SphK1/S1P and TGF-β-induced miR-21 in renal TECs and may represent a novel therapeutic target in renal fibrosis.
authors.affiliation: Department of Nephrology, the 94th Hospital of Chinese People's Liberation Army (Changcheng Hospital affiliated to Nanchang University), Nanchang 330002, China xiujuan_liu796@163.com.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Nephrology, Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing 100853, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Hong
authors.affiliation: Department of Nephrology, the 94th Hospital of Chinese People's Liberation Army (Changcheng Hospital affiliated to Nanchang University), Nanchang 330002, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Nephrology, the 94th Hospital of Chinese People's Liberation Army (Changcheng Hospital affiliated to Nanchang University), Nanchang 330002, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Nephrology, the 94th Hospital of Chinese People's Liberation Army (Changcheng Hospital affiliated to Nanchang University), Nanchang 330002, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zou
authors.affiliation: Department of Nephrology, the 94th Hospital of Chinese People's Liberation Army (Changcheng Hospital affiliated to Nanchang University), Nanchang 330002, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Xu
mesh_terms: D015152:Blotting, Northern; D002470:Cell Survival; D004847:Epithelial Cells / Q000502:physiology*; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D035683:MicroRNAs / Q000096:biosynthesis*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000099157:Sphingosine Kinase
chemical_list: D008246:Lysophospholipids; D035683:MicroRNAs; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D016212:Transforming Growth Factor beta; D000099157:Sphingosine Kinase; C524940:MIRN21 microRNA, human; C060506:sphingosine 1-phosphate
keywords: miRNA-21; renal fibrosis; sphingosine kinase; sphingosine-1-phosphate; tubular epithelial cells