Sphingosine Kinase 1 Regulates Tumor Necrosis Factor-mediated RANTES Induction through p38 Mitogen-activated Protein Kinase but Independently of Nuclear Factor κB Activation

• Published in: The Journal of biological chemistry 2013-09, Vol.288 (38), p.27667-27679
• Main Authors: Adada, Mohamad M., Orr-Gandy, K. Alexa, Snider, Ashley J., Canals, Daniel, Hannun, Yusuf A., Obeid, Lina M., Clarke, Christopher J.
• Format: Article
• Language: English
• Subjects: Animals; Chemokine CCL5 - biosynthesis; Chemokine CCL5 - genetics; Chemokines; Enzyme Activation - physiology; HeLa Cells; Humans; I-kappa B Kinase - genetics; I-kappa B Kinase - metabolism; Inflammation; Lipids; Mice; Mice, Knockout; NF-kappa B (NF-KB); NF-kappa B - genetics; NF-kappa B - metabolism; p38 MAPK; p38 Mitogen-Activated Protein Kinases - genetics; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation - physiology; Phosphotransferases (Alcohol Group Acceptor) - genetics; Phosphotransferases (Alcohol Group Acceptor) - metabolism; RANTES; Sphingosine Kinase; Sphingosine-1-phosphate; Tumor Necrosis Factor (TNF); Tumor Necrosis Factor-alpha - genetics; Tumor Necrosis Factor-alpha - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.489443

Sphingosine kinase 1 (SK1) produces the pro-survival sphingolipid sphingosine 1-phosphate and has been implicated in inflammation, proliferation, and angiogenesis. Recent studies identified TRAF2 as a sphingosine 1-phosphate target, implicating SK1 in activation of the NF-κB pathway, but the functional consequences of this connection on gene expression are unknown. Here, we find that loss of SK1 potentiates induction of the chemokine RANTES (regulated on activation, normal T cell expressed and secreted; also known as CCL5) in HeLa cells stimulated with TNF-α despite RANTES induction being highly dependent on the NF-κB pathway. Additionally, we find that SK1 is not required for TNF-induced IKK phosphorylation, IκB degradation, nuclear translocation of NF-κB subunits, and transcriptional NF-κB activity. In contrast, loss of SK1 prevented TNF-induced phosphorylation of p38 MAPK, and inhibition of p38 MAPK, like SK1 knockdown, also potentiates RANTES induction. Finally, in addition to RANTES, loss of SK1 also potentiated the induction of multiple chemokines and cytokines in the TNF response. Taken together, these data identify a potential and novel anti-inflammatory function of SK1 in which chemokine levels are suppressed through SK1-mediated activation of p38 MAPK. Furthermore, in this system, activation of NF-κB is dissociated from SK1, suggesting that the interaction between these pathways may be more complex than currently thought. Background: SK1 is widely involved in promoting inflammatory diseases. Results: Unexpectedly, loss of SK1 caused an increase in chemokines upon TNF stimulation. This occurred through regulation of p38 MAPK but independently of NF-κB. Conclusion: SK1 negatively regulates RANTES expression through the p38 MAPK pathway. Significance: Targeting SK1 in therapy may affect inflammatory conditions by up-regulating chemokines independently of NF-κB.