Unique suppression of prostaglandin H synthase-2 expression by inhibition of histone deacetylation, specifically in human amnion but not adjacent choriodecidua.

The key molecular regulatory mechanisms that govern and coordinate the molecular alterations that underpin the process of human labor remain incompletely understood although enhanced intrauterine prostaglandin production is known to be requisite. Studies from cancer tissues have indicated that at least one key enzyme of prostaglandin biosynthesis can have its activity severely reduced by increased histone deacetylation and enhanced DNA methylation status. We have advanced the hypothesis that similar regulation may occur in intrauterine tissues during pregnancy to prevent inadvertent activation of this powerful initiating signal by dampening responses to premature activation by agents such as cytokines. Our studies have shown that responsiveness of amnion, a key intrauterine tissue, to interleukin-1beta is abrogated by inhibition of histone deacetylation, whereas PGDH amounts were increased basally. The findings do integrate well with others concerning progesterone (inhibitory) actions such that a decrease in the level of histone acetylation in human gestational tissues near term might herald a coordinated series of events that all result in a positive drive for parturition. Hence, a new level of regulatory action and potential therapeutic targets for pathologies such as preterm labor can flow from these findings.