title: Promoter methylation of Egr-1 site contributes to fetal hypoxia-mediated PKCε gene repression in the developing heart.
abstract: Fetal hypoxia causes protein kinase Cε (PKCε) gene repression in the heart resulting in heightened ischemic injury in male offspring in a sex-dependent manner. The present study tested the hypothesis that heightened methylation of the early growth response factor-1 (Egr-1) binding site at PKCε gene promoter contributes to sex dimorphism of hypoxia-induced programming of PKCε gene repression in the developing heart. Pregnant rats were divided into normoxic and hypoxic (10.5% O2 from day 15 to 21 of gestation) groups. Hypoxia selectively decreased PKCε mRNA and protein abundance in the heart of male, but not female, near-term (21 days) fetuses. Methylation of the CpG site at the Egr-1 binding site of PKCε promoter was significantly increased in the male hearts by hypoxia, resulting in decreased Egr-1 binding affinity and reduced Egr-1 binding to the PKCε promoter. Nuclear Egr-1 levels were not affected by hypoxia. There was significantly higher abundance of estrogen receptor α (ERα) and β (ERβ) isoforms in female than in male fetal hearts, which were not significantly altered by hypoxia. Both ERα and ERβ bind to the Egr-1 binding site with significant greater levels in the female fetal hearts. The increased methylation with reduced Egr-1 binding and PKCε gene repression persisted in 3-mo-old adult male hearts in a sex-dependent manner. The results indicate a key role for heightened methylation of the Egr-1 binding site in hypoxia-mediated programming of PKCε gene repression in the developing heart and suggest a novel protective mechanism of ER by binding to the Egr-1 binding site in epigenetic regulation of PKCε gene expression patterns in the early developmental stage.
authors: Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
authors: Man
authors: M
authors: Chen
authors: Fuxia
authors: F
authors: Xiong
authors: Lubo
authors: L
authors: Zhang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000963:Antimetabolites / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D001665:Binding Sites; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D051766:Early Growth Response Protein 1 / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D044127:Epigenesis, Genetic / Q000235:genetics / Q000502:physiology*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism; D005260:Female; D005311:Fetal Hypoxia / Q000235:genetics*; D006321:Heart / Q000254:growth & development*; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D011247:Pregnancy; D051744:Protein Kinase C-epsilon / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D012727:Sex Characteristics
chemical_list: D000963:Antimetabolites; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D051744:Protein Kinase C-epsilon; D001374:Azacitidine
keywords: DNA methylation; Egr-1; PKCε; heart; hypoxia