title: Pharmacological Inhibition of O-GlcNAcase Does Not Increase Sensitivity of Glucocorticoid Receptor-Mediated Transrepression.
abstract: Glucocorticoid signaling regulates target genes by multiple mechanisms, including the repression of transcriptional activities of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) though direct protein-protein interactions and subsequent O-GlcNAcylation of RNA polymerase II (pol II). Recent studies have shown that overexpression of O-linked β-N-acetylglucosamine transferase (OGT), which adds an O-linked β-N-acetylglucosamine (O-GlcNAc) group to the C-terminal domain of RNA pol II, increases the transrepression effects of glucocorticoids (GC). As O-GlcNAcase (OGA) is an enzyme that removes O-GlcNAc from O-GlcNAcylated proteins, we hypothesized that the potentiation of GC effects following OGT overexpression could be similarly observed via the direct inhibition of OGA, inhibiting O-GlcNAc removal from pol II. Here we show that despite pharmacological evidence of target engagement by a selective small molecule inhibitor of OGA, there is no evidence for a sensitizing effect on glucocorticoid-mediated effects on TNF-α promoter activity, or gene expression generally, in human cells. Furthermore, inhibition of OGA did not potentiate glucocorticoid-induced apoptosis in several cancer cell lines. Thus, despite evidence for O-GlcNAc modification of RNA pol II in GR-mediated transrepression, our data indicate that pharmacological inhibition of OGA does not potentiate or enhance glucocorticoid-mediated transrepression.
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stivers
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Lauren
authors.initials: L
authors.lastname: Harmonay
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Hicks
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Mehmet
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Melody
authors.initials: M
authors.lastname: Morris
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Gain M
authors.initials: GM
authors.lastname: Robinson
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Strack
authors.affiliation: Merck & Co., Inc., Rahway, New Jersey, United States of America.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Savage
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Zaller
authors.affiliation: Merck & Co., Inc., Rahway, New Jersey, United States of America.
authors.forename: Izabela
authors.initials: I
authors.lastname: Zwierzynski
authors.affiliation: Merck & Co., Inc., Boston, Massachusetts, United States of America.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Brandish
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000235:genetics; D020128:Inhibitory Concentration 50; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D017351:N-Acetylglucosaminyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011239:Prednisolone / Q000494:pharmacology; D011714:Pyrans / Q000494:pharmacology*; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D020298:U937 Cells
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D011714:Pyrans; D011965:Receptors, Glucocorticoid; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; C572247:thiamet G; D003907:Dexamethasone; D011239:Prednisolone; D017351:N-Acetylglucosaminyltransferases; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase