Sphingosine-1-phosphate (S1P) is a potent sphingolipid mediator that regulates diverse cellular processes important for cancer progression including cell growth and survival, invasion, angiogenesis, lymphocyte trafficking, and inflammation, among others. Although S1P is produced inside cells by two closely related sphingosine kinases, SphK1 and SphK2, most of the research to date in the S1P field has been concentrated on its actions as a ligand for the five S1P receptors, and prior to our work, no intracellular targets had been recognized. We recently identified HDAC1/2 as the first direct intracellular targets of S1P, and demonstrated that S1P, produced by nuclear SphK2, is an endogenous small molecule inhibitor of these enzymes, linking nuclear S1P to epigenetic regulation of gene expression. In preliminary studies, we have discovered that TNF receptor-associated factor 2 (TRAF2), a key component in activation of NF-kB, is another novel intracellular target of S1P. Our data indicates that S1P may be the missing cofactor for the E3 ubiquitin ligase activity of TRAF2, suggesting a new paradigm for regulation of NF-kB, a transcription factor important for cancer and inflammation. In this proposal, we will examine the hypothesis that the location of S1P production dictates its functions and that S1P is not only a ligand for the S1PRs but also serves as an intracellular molecular switch that regulates the activity of its targets, HDAC1/2 and TRAF2, important for cancer and inflammation. In the first aim, we will determine the role of S1P produced by SphK2 in the nucleus as an endogenous regulator of HDACs. In the second, we will determine the role of S1P produced by SphK1 as a direct regulator of the E3 ligase activity of TRAFs, lysine 63-linked polyubiquitination, and NF-kB signaling.
The third aim will address the importance of S1P and its regulation of HDAC1/2 and TRAF2 in a mouse model of chronic inflammation leading to cancer. These three aims represent a novel and unique approach to understanding S1P biology and its multi-faceted actions and will open new areas of research. This proposal provides a paradigm shift from "inside-out" signaling by S1P to include important signaling inside cells and will provide evidence that S1P is one of the critical factors that bridges chronic inflammation to tumor promotion and progression.
The bioactive sphingolipid metabolite S1P and the kinases that produce it, SphK1 and SphK2, have emerged as critical regulators of numerous fundamental biological processes important for health and disease, particularly cancer and inflammation. It is difficult to find an area of cell biology and physiology in which S1P does not have important if not key roles. This proposal will be a major contribution towards understanding the enigmatic nature of the pleiotropic actions of S1P, modifying the focus of research on S1P signaling at the cell surface to include signaling inside cells, and will have important clinical applications for inflammation and cancer.
|Huang, Wei-Ching; Liang, Jie; Nagahashi, Masayuki et al. (2016) Sphingosine-1-phosphate phosphatase 2 promotes disruption of mucosal integrity, and contributes to ulcerative colitis in mice and humans. FASEB J 30:2945-58|
|Shao, Huanjie; Mohamed, Esraa M; Xu, Guoyan G et al. (2016) Carnitine palmitoyltransferase 1A functions to repress FoxO transcription factors to allow cell cycle progression in ovarian cancer. Oncotarget 7:3832-46|
|Aoki, Hiroaki; Aoki, Masayo; Yang, Jing et al. (2016) Murine model of long-term obstructive jaundice. J Surg Res 206:118-125|
|Nagahashi, Masayuki; Yamada, Akimitsu; Miyazaki, Hiroshi et al. (2016) Interstitial Fluid Sphingosine-1-Phosphate in Murine Mammary Gland and Cancer and Human Breast Tissue and Cancer Determined by Novel Methods. J Mammary Gland Biol Neoplasia 21:9-17|
|Oskeritzian, Carole A; Hait, Nitai C; Wedman, Piper et al. (2015) The sphingosine-1-phosphate/sphingosine-1-phosphate receptor 2 axis regulates early airway T-cell infiltration in murine mast cell-dependent acute allergic responses. J Allergy Clin Immunol 135:1008-18.e1|
|Hait, N C; Avni, D; Yamada, A et al. (2015) The phosphorylated prodrug FTY720 is a histone deacetylase inhibitor that reactivates ERÎ± expression and enhances hormonal therapy for breast cancer. Oncogenesis 4:e156|
|Nagahashi, Masayuki; Takabe, Kazuaki; Liu, Runping et al. (2015) Conjugated bile acid-activated S1P receptor 2 is a key regulator of sphingosine kinase 2 and hepatic gene expression. Hepatology 61:1216-26|
|Booth, Laurence; Roberts, Jane L; Tavallai, Mehrad et al. (2015) OSU-03012 and Viagra Treatment Inhibits the Activity of Multiple Chaperone Proteins and Disrupts the Blood-Brain Barrier: Implications for Anti-Cancer Therapies. J Cell Physiol 230:1982-98|
|Booth, Laurence; Roberts, Jane L; Cruickshanks, Nichola et al. (2015) PDE5 inhibitors enhance celecoxib killing in multiple tumor types. J Cell Physiol 230:1115-27|
|Liu, Mingxia; Allegood, Jeremy; Zhu, Xuewei et al. (2015) Uncleaved ApoM signal peptide is required for formation of large ApoM/sphingosine 1-phosphate (S1P)-enriched HDL particles. J Biol Chem 290:7861-70|
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