15-Deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) mediates repression of TNF-alpha by decreasing levels of acetylated histone H3 and H4 at its promoter.
Prostaglandin metabolite 15-Deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) is known to inhibit a number of pro-inflammatory cytokines as well as being a ligand for nuclear receptor PPARgamma. We investigated the ability of 15d-PGJ2 to inhibit TNF-alpha gene expression through mechanisms that involve histone modification. Pretreatment with 15d-PGJ2 (10 microM) inhibited LPS-stimulated TNF-alpha mRNA in THP-1 monocytes or PMA-differentiated cells to nearly basal levels. A specific PPARgamma ligand, GW1929, failed to inhibit LPS-induced TNF-alpha mRNA expression nor did a PPARgamma antagonist, GW9662, alter the repression of TNF-alpha mRNA in LPS-stimulated cells pretreated with 15d-PGJ2 suggesting a PPARgamma-independent inhibition of TNF-alpha mRNA in THP-1 cells. Transfection studies with a reporter construct and subsequent treatment with 15d-PGJ2 demonstrated a dose-dependent inhibition of the TNF-alpha promoter. Additional studies demonstrated that inhibition of histone deacetylases with trichostatin A (TSA) or overexpression of histone acetyltransferase CBP could overcome 15d-PGJ2-mediated repression of the TNF-alpha promoter, suggesting that an important mechanism whereby 15d-PGJ2 suppresses a cytokine is through factors that regulate histone modifications. To examine the endogenous TNF-alpha promoter, chromatin immunoprecipitations (ChIP) were performed. ChIP assays demonstrated that LPS stimulation induced an increase in histone H3 and H4 acetylation at the TNF-alpha promoter, which was reduced in cells pretreated with 15d-PGJ2. These results highlight the ability of acetylation and deacetylation factors to affect the TNF-alpha promoter and demonstrate that an additional important mechanism whereby 15d-PGJ2 mediates TNF-alpha transcriptional repression by altering levels of acetylated histone H3 and H4 at its promoter.
Engdahl
Ryan
R
Temple University School of Medicine, Department of Surgery, 3400 North Broad Street, Philadelphia, PA 19140, USA. rengdahl@temple.edu
Monroy
M Alexandra
MA
Daly
John M
JM
D000107:Acetylation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology*; D015230:Prostaglandin D2 / Q000008:administration & dosage / Q000031:analogs & derivatives*; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
C477819:15-deoxyprostaglandin J2; D006657:Histones; D014409:Tumor Necrosis Factor-alpha; D015230:Prostaglandin D2