Prostaglandin E₂increases fibroblast gene‐specific and global DNA methylationviaincreased DNA methyltransferase expression

Abstract

Although alterations in DNA methylation patterns have been associated with specific diseases and environmental exposures, the mediators and signaling pathways that direct these changes remain understudied. The bioactive lipid mediator prostaglandin E(2) (PGE(2)) has been shown to exert a myriad of effects on cell survival, proliferation, and differentiation. Here, we report that PGE(2) also signals to increase global DNA methylation and DNA methylation machinery in fibroblasts. HumanMethylation27 BeadChip array analysis of primary fetal (IMR-90) and adult lung fibroblasts identified multiple genes that were hypermethylated in response to PGE(2). PGE(2), compared with nontreated controls, increased expression and activity (EC(50)∼10(7) M) of one specific isoform of DNA methyltransferase, DNMT3a. Silencing of DNMT3a negated the ability of PGE(2) to increase DNMT activity. The increase in DNMT3a expression was mediated by PGE(2) signaling via its E prostanoid 2 receptor and the second messenger cAMP. PGE(2), compared with the untreated control, increased the expression and activity of Sp1 and Sp3 (EC(50)∼3×10(7) M), transcription factors known to increase DNMT3a expression, and inhibition of these transcription factors abrogated the PGE(2) increase of DNMT3a expression. These findings were specific to fibroblasts, as PGE(2) decreased DNMT1 and DNMT3a expression in RAW macrophages. Taken together, these findings establish that DNA methylation is regulated by a ubiquitous bioactive endogenous mediator. Given that PGE(2) biosynthesis is modulated by environmental toxins, various disease states, and commonly used pharmacological agents, these findings uncover a novel mechanism by which alterations in DNA methylation patterns may arise in association with disease and certain environmental exposures.

Reversal of Myofibroblast Differentiation by Prostaglandin E2

“…Our data suggest that the inhibition of adhesion signaling by PGE 2 represents a critical mechanism for the reversal of myofibroblast differentiation. We do note, however, that treatment of myofibroblasts with a FAK inhibitor did not reverse a-SMA expression to the same degree as PGE 2 , suggesting that PGE 2 may employ other mechanisms (e.g., activation of PTEN/inhibition of Akt [18], activation of the wnt/b-catenin signaling pathways [36], and modification of genespecific DNA methylation patterns [33]) that are responsible for reversal of myofibroblast differentiation.…”

“…Previous studies have implicated FAK (30) and Akt (27) signaling, as well as endoplasmic reticulum stress (31), in myofibroblast differentiation; in addition, an epigenetic signature distinct from that of fibroblasts has been observed in myofibroblasts (32). All of these mechanisms represent potential targets that might mediate phenotypic reversal by PGE 2 ; indeed, this prostanoid is known to inhibit FAK and Akt activation (6,28), and to increase global DNA methylation in fibroblasts (33). Here, we observed that levels of Tyr397-phosphorylated FAK in myofibroblasts decreased within 15 minutes of PGE 2 treatment, and that inhibition of FAK was capable of reversing the myofibroblast phenotype.…”

Getting more for your marrow: Boosting hematopoietic stem cell numbers with PGE2

“…Such changes could be due, in part, to alterations in the epigenetic state of the cells. PGE 2 has been shown to affect DNA methylation patterns in the intestine and increase global DNA methylation via induction of DNMT3a in fibroblasts 38 . It will be interesting in future studies to explore potential roles for epigenetic modifiers and to examine DNA methylation patterns before, during and after treatment with dmPGE 2 .…”

Candidate chromosome 1 disease susceptibility genes for Sjogren's syndrome xerostomia are narrowed by novel NOD.B10 congenic mice

“…COX-2 is a critical modulator of PGE2 which, among its diverse functions, can mediate epigenetic changes through regulating the transcription of DNA methyltransferases, DNMT1, DNTM3a, and DNTM3b [59, 60]. Thus, there is an intriguing possibility that COX-2-regulated PGE2 influences the expression of proximal genes.…”