title: Elevated Nuclear and Cytoplasmic FTY720-Phosphate in Mouse Embryonic Fibroblasts Suggests the Potential for Multiple Mechanisms in FTY720-Induced Neural Tube Defects.
abstract: FTY720 (fingolimod) is a U.S. Food and Drug Administration-approved drug to treat relapsing remitting multiple sclerosis. FTY720 treatment in pregnant inbred LM/Bc mice results in approximately 60% of embryos having a neural tube defect (NTD). Sphingosine kinases (Sphk1, Sphk2) phosphorylate FTY720 in vivo to form the bioactive metabolite FTY720-1-phosphate (FTY720-P). Cytoplasmic FTY720-P is an agonist for 4 of the 5 sphingosine-1-phosphate (S1P) receptors (S1P1, 3-5) and can also act as a functional antagonist of S1P1, whereas FTY720-P generated in the nucleus inhibits histone deacetylases (HDACs), leading to increased histone acetylation. This study demonstrates that treatment of LM/Bc mouse embryonic fibroblasts (MEFs) with FTY720 results in a significant accumulation of FTY720-P in both the cytoplasmic and nuclear compartments. Elevated nuclear FTY720-P is associated with decreased HDAC activity and increased histone acetylation at H3K18 and H3K23 in LM/Bc MEFs. Treatment of LM/Bc MEFs with FTY720 and a selective Sphk2 inhibitor, ABC294640, significantly reduces the amount of FTY720-P that accumulates in the nucleus. The data provide insight into the relative amounts of FTY720-P generated in the nuclear versus cytoplasmic subcellular compartments after FTY720 treatment and the specific Sphk isoforms involved. The results of this study suggest that FTY720-induced NTDs may involve multiple mechanisms, including: (1) sustained and/or altered S1P receptor activation and signaling by FTY720-P produced in the cytoplasm and (2) HDAC inhibition and histone hyperacetylation by FTY720-P generated in the nucleus that could lead to epigenetic changes in gene regulation.
authors.affiliation: *Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68178 and nicolegardner@creighton.edu.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gardner
authors.affiliation: USDA-ARS, Toxicology and Mycotoxin Research Unit, Athens, Georgia 30605.
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Riley
authors.affiliation: USDA-ARS, Toxicology and Mycotoxin Research Unit, Athens, Georgia 30605.
authors.forename: Jency L
authors.initials: JL
authors.lastname: Showker
authors.affiliation: USDA-ARS, Toxicology and Mycotoxin Research Unit, Athens, Georgia 30605.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Voss
authors.affiliation: *Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68178 and.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sachs
authors.affiliation: *Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68178 and.
authors.forename: Joyce R
authors.initials: JR
authors.lastname: Maddox
authors.affiliation: *Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68178 and.
authors.forename: Janee B
authors.initials: JB
authors.lastname: Gelineau-van Waes
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003593:Cytoplasm / Q000187:drug effects* / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000187:drug effects; D008815:Mice, Inbred Strains; D009436:Neural Tube Defects / Q000139:chemically induced* / Q000196:embryology / Q000378:metabolism; D010755:Organophosphates / Q000378:metabolism / Q000633:toxicity*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity
chemical_list: C525008:FTY 720P; D006657:Histones; D010755:Organophosphates; D006655:Histone Deacetylases; D013110:Sphingosine
keywords: ABC294640; FTY720; S1P receptors; histone deacetylase inhibition; histone post-translational modification (PTM); sphingosine kinase