RESUMO
The intrahepatic cholestasis of pregnancy (ICP) is a multifactorial liver disorder which pathogenesis involves the interplay among abnormal bile acid (BA) levels, sex hormones, environmental factors, and genetic susceptibility. The dynamic nature of ICP that usually resolves soon after delivery suggests the possibility that its pathobiology is under epigenetic modulation. We explored the status of white blood peripheral cells-DNA methylation of CpG-enriched sites at the promoter of targeted genes (FXR/NR1H4, PXR/NR1I2, NR1I3, ESR1, and ABCC2) in a sample of 88 ICP patients and 173 healthy pregnant women in the third trimester of their pregnancies. CpG dinucleotides at the gene promoter of nuclear receptors subfamily 1 members and ABCC2 transporter were highly methylated during healthy pregnancy. We observed significant differences at the distal (-1890) and proximal promoter (-358) CpG sites of the FXR/NR1H4 and at the distal PXR/NR1I2 (-1224) promoter, which were consistently less methylated in ICP cases when compared with controls. In addition, we observed that methylation at FXR/NR1H4-1890 and PXR/NR1I2-1224 promoter sites was highly and positively correlated with BA profiling, particularly, conjugated BAs. Conversely, methylation level at the proximal FXR/NR1H4-358 CpG site was significantly and negatively correlated with the primary cholic and secondary deoxycholic acid. In vitro exploration showed that epiallopregnanolone sulfate, a reported FXR inhibitor, regulates the transcriptional activity of FXR/NR1H4 but seems to be not involved in the methylation changes. In conclusion, the identification of epigenetic marks in target genes provides a basis for the understanding of adverse liver-related pregnancy outcomes, including ICP.
Assuntos
Colestase Intra-Hepática/metabolismo , Metilação de DNA , Fenótipo , Complicações na Gravidez/metabolismo , Regiões Promotoras Genéticas , Receptores Citoplasmáticos e Nucleares/metabolismo , Adulto , Linhagem Celular Tumoral , Colestase Intra-Hepática/genética , Colestase Intra-Hepática/patologia , Receptor Constitutivo de Androstano , Epigênese Genética/efeitos dos fármacos , Epigênese Genética/genética , Feminino , Humanos , Masculino , Proteína 2 Associada à Farmacorresistência Múltipla , Gravidez , Complicações na Gravidez/genética , Complicações na Gravidez/patologia , Pregnanolona/análogos & derivados , Pregnanolona/farmacologia , Receptores Citoplasmáticos e Nucleares/genética , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/genéticaRESUMO
UNLABELLED: In this study, we contrasted the hypothesis that maternal diet during pregnancy has an impact on fetal metabolic programming through changes in liver mitochondrial DNA (mtDNA) content and transcriptional activity of Ppargc1a and that these effects are sex specific. METHODS: Rats were fed either high-fat (HFD) or standard chow diet (SCD) during gestation and lactation. The resulting adult male and female offspring were fed either HFD or SCD for an 18-week period, generating eight experimental groups. RESULTS: Maternal HFD feeding during pregnancy is associated with a decreased liver mtDNA copy number (P<.008). This effect was independent of the offspring sex or diet, and was significantly associated with fatty liver when dams were fed HFD (P<.05, adjusted by homeostasis model assessment of insulin resistance, HOMA-IR). We also found that maternal HFD feeding results in a male-specific significant reduction of the liver abundance of Ppargc1a mRNA (P<.004), which significantly impacted peripheral insulin resistance. Liver expression of Ppargc1a was inversely correlated with HOMA-IR (R=-0.53, P<.0003). Only male offspring exposed to a chronic metabolic insult in adult life were insulin resistant and hyperleptinemic, and showed abnormal liver and abdominal fat accumulation. Liver abundance of Tfam, Nrf1, Hnf4a, Pepck and Ppparg mRNA was not associated with maternal programming. In conclusion, maternal high-fat diet feeding during pregnancy programs liver mtDNA content and the transcriptional activity of Ppargc1a, which strongly modulates, in a sex-specific manner, glucose homeostasis and organ fat accumulation in adult life after exposure to a nutritional insult.
Assuntos
DNA Mitocondrial , Dieta Hiperlipídica/efeitos adversos , Fígado/fisiologia , Síndrome Metabólica/genética , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , Animais , Peso Corporal , Feminino , Dosagem de Genes , Regulação da Expressão Gênica , Fator 4 Nuclear de Hepatócito/genética , Resistência à Insulina/genética , Masculino , Síndrome Metabólica/etiologia , Síndrome Metabólica/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fenótipo , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Proteínas de Ligação a RNA/genética , Ratos Wistar , Fatores Sexuais , Fatores de Transcrição/genéticaRESUMO
Pterins are a family of heterocyclic compounds present in a wide range of living systems that participate in relevant biological functions and are involved in different photobiological processes. 6-Methylpterin (MPT) was investigated for its efficiency of singlet-oxygen (1O2) production and quenching in aqueous solution. The quantum yields of 1O2 production (phi(delta)) was determined by measurements of the 1O2 luminescence in the near-infrared upon continuous excitation of the sensitizer. Values of phi(delta) were found to be 0.10 +/- 0.02 and 0.14 +/- 0.02 in acidic and alkaline media, respectively. Studies of the photooxidation of MPT in acidic (pH = 5.0-6.0) and alkaline (pH = 10.2-10.8) aqueous solutions at 350 nm and room temperature have been performed. The photochemical reactions were followed by UV-visible spectrophotometry, high-performance liquid chromatography and an enzymatic method for H2O2 determination. MPT is not light sensitive in the absence of oxygen, but it undergoes a photooxidation reaction in the presence of oxygen, yielding several nonpteridinic products. The quantum yields of MPT disappearance were determined and values of 2.4 (+/-0.5) x 10(-4) and 8.1 (+/-0.8) x 10(-4) were obtained in acidic and alkaline media, respectively. H2O2 was detected and quantified in irradiated solutions of MPT. The rate constant of the chemical reaction between 1O2 and MPT (k(r)) was determined to be 4.9 x 10(6) M(-1) s(-1) in alkaline medium and the role of 1O2 in the photooxidation of MPT is discussed.