Prostaglandin H synthase-2 gene regulation in the amnion at labour: histone acetylation and nuclear factor kappa B binding to the promoter in vivo

Abstract

Increased prostaglandin H synthase-2 (PGHS-2) expression in the amnion is critical for the production of prostaglandins that induce labour. The aim of the present investigation was to determine whether PGHS-2 gene activity is controlled by NFkappaB transcription factors in term amnion in vivo as suggested by in vitro findings. Amnion membranes were collected after elective Caesarean section (n = 14) or spontaneous labour (n = 12) at term, and histone acetylation and transcription factor binding to the PGHS-2 and IkappaBalpha promoters were determined in fresh tissues by chromatin immunoprecipitation. High level of histone-3 and -4 acetylation was detected in the proximal 1000 bp region of the PGHS-2 promoter indicating permissive chromatin structure in an area that contains two consensus NFkappaB binding sites and other transcription factor binding motifs. The TATA-box was occupied by TATA-binding protein (TBP) demonstrating that the PGHS-2 gene was transcriptionally active before and after labour. NFkappaB (p65 and p50) binding to the consensus sites, however, was detected only before, but not after, labour. Moreover, NFkappaB factor binding before labour was unrelated to TBP binding to the PGHS-2 TATA-box in the same tissues. Further, p65 binding to the NFkappaB-responsive IkappaBalpha promoter increased at labour and correlated strongly with TBP binding to the TATA-box of this gene. We conclude that the proximal 1000 bp region is involved in PGHS-2 promoter regulation in term amnion. The NFkappaB system is activated at labour and stimulates the IkappaBalpha gene, but the NFkappaB factors do not drive PGHS-2 transcription using consensus promoter sites in normal term amnion in vivo.

Long Term Transcriptional Reactivation of Epigenetically Silenced Genes in Colorectal Cancer Cells Requires DNA Hypomethylation and Histone Acetylation

“…Increased acetylation at hypermethylated transcription start sites which lead to long term reactivation of anti-proliferative genes may be beneficial in the treatment of tumours when this information is known. This mechanism would be in addition to the reported synergistic apoptotic effect of methyltransferase and histone deacetylase inhibitors [28], [38].…”

“…Sonication was performed using 8×30-second cycles at 60% duty cycle in an ice bath and samples were further cooled for 30 seconds in between sonication cycles. Chromatin Immunoprecipitation was performed as previously described [28] with slight modifications. Antibodies were obtained from Upstate (Catalog numbers; α-H3Ac 06-599, α-H3K4me3 07-473, α-H3K9me3 17-625, α-H3K27me3 17-622) with the exception of the Rabbit IgG non-specific antibody from Santa Cruz Biotechnology (Catalog number SC2027).…”

Nuclear factor-kappa B localization and function within intrauterine tissues from term and preterm labor and cultured fetal membranes

“…Similarly, using ELISA-based DNA binding assays, Lappas and Rice have reported that term labor was associated with increased p65 activity in the amnion (but not the choriodecidua) following term labor [27]. In addition, using chromatin immunoprecipitation (ChIP), Mitchell et al found that p65 binding to the NF-κB responsive IκBα gene promoter (but not the cyclooxygenase-2 promoter) increased in the amnion following term labor [31]. In contrast with these prior reports, we were unable to document biochemical evidence of increased p65 binding activity in either the amniotic or the choriodecidual tissues following term labor.…”

The intrauterine renin–angiotensin system: Sex‐specific effects on the prevalence of spontaneous preterm birth

“…Many of these effects are mediated by the key inflammatory transcription factor NF‐κB . NF‐κB controls the genes that code for cytokines, chemokines, and enzymes that in turn synthesise prostaglandins . Silva et al.…”