1. Academic Validation
  2. Sphingosine kinase 2 cooperating with Fyn promotes kidney fibroblast activation and fibrosis via STAT3 and AKT

Sphingosine kinase 2 cooperating with Fyn promotes kidney fibroblast activation and fibrosis via STAT3 and AKT

  • Biochim Biophys Acta Mol Basis Dis. 2018 Nov;1864(11):3824-3836. doi: 10.1016/j.bbadis.2018.09.007.
Xingxing Zhu 1 Dongyan Shi 1 Kelei Cao 1 Dongqing Ru 1 Jiafa Ren 2 Zebing Rao 1 Yunzi Chen 1 Qiang You 3 Chunsun Dai 2 Lixin Liu 4 Hong Zhou 5
Affiliations

Affiliations

  • 1 Department of Immunology, Nanjing Medical University, Nanjing, Jiangsu 211166, China.
  • 2 Second Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210011, China.
  • 3 Department of Immunology, Nanjing Medical University, Nanjing, Jiangsu 211166, China; Second Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210011, China.
  • 4 Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
  • 5 Department of Immunology, Nanjing Medical University, Nanjing, Jiangsu 211166, China; Second Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210011, China. Electronic address: hzhou@njmu.edu.cn.
Abstract

Sphingosine kinases (Sphks) are the rate-limiting Enzymes in the conversion of sphingosine to biologically active sphingosine-1-phosphate. The present study aimed to determine the role of SphK2 and its downstream targets in renal fibroblast activation and interstitial fibrosis. In the kidney interstitium of patients with renal fibrosis, SphK2high-expressing cells (mainly interstitial fibroblasts) were significantly elevated and highly correlated with disease progression in patients. In a murine model of renal interstitial fibrosis, SphK2 was upregulated in the kidney of wild-type mice in response to disease progression. Importantly, Sphk2-knockout (KO) mice exhibited significantly lower levels of extracellular matrix (ECM) production and a suppressed inflammatory response in the kidney tissues, compared to those in their wild-type counterparts, whereas the expression of TGF-β1 was unaffected. TGF-β1 effectively upregulated SphK2 expression in the renal interstitial fibroblast line, NRK-49F, independent of canonical Smad signaling activation. Furthermore, siRNA-mediated SphK2 knockdown or suppression of SphK2 activity by ABC294640 exposure effectively attenuated Akt and STAT3 activation and ECM production, but had no effects on SMAD2 and SMAD3 activation. SphK2 phosphorylated Fyn to activate downstream STAT3 and Akt, thereby promoting ECM synthesis. Therefore, our findings indicate that targeting Sphk2-Fyn-STAT3/Akt signaling pathway may be a novel therapeutic approach for renal fibrosis.

Keywords

Fibroblast activation; Fyn; Non-canonical Smad signaling; Renal interstitial fibrosis; Sphk2.

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