| Autor: |
Stivers PJ; Merck & Co., Inc., Boston, Massachusetts, United States of America., Harmonay L; Merck & Co., Inc., Boston, Massachusetts, United States of America., Hicks A; Merck & Co., Inc., Boston, Massachusetts, United States of America., Mehmet H; Merck & Co., Inc., Boston, Massachusetts, United States of America., Morris M; Merck & Co., Inc., Boston, Massachusetts, United States of America., Robinson GM; Merck & Co., Inc., Boston, Massachusetts, United States of America., Strack PR; Merck & Co., Inc., Boston, Massachusetts, United States of America., Savage MJ; Merck & Co., Inc., Rahway, New Jersey, United States of America., Zaller DM; Merck & Co., Inc., Boston, Massachusetts, United States of America., Zwierzynski I; Merck & Co., Inc., Rahway, New Jersey, United States of America., Brandish PE; Merck & Co., Inc., Boston, Massachusetts, United States of America. |
| Abstrakt: |
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. |
