DNA Methylation Variability in a Single Locus of the RXRα Promoter from Umbilical Vein Blood at Term Pregnancy

Abstract

DNA methylation status of RXRα gene promoter has been correlated with maternal diet during early pregnancy, and associated with offspring's adiposity and bone mineral content. In adult life, increased methylation of RXRα promoter region is associated with myocardium pathologies. Early growth response proteins (EGR) are zinc finger transcription factors associated with several cellular pathways such as inflammation, apoptosis, and cardiopathies. DNA-binding sequences of EGR proteins have been reported in the RXRα gene promoter using chromatin immunoprecipitation methods. Here, we used correlations between the maternal pre-pregnancy body mass index (p-BMI), gestational weight gain (GWG), and birth weight (BW) as indirect indicators of the maternal nutritional status as modifier of DNA methylation in the offspring. DNA methylation status from newborns' umbilical vein blood in full-term pregnancy was evaluated in a short sequence (116 pb) of the RXRα gene promoter that contains the elements of response sequence for EGR proteins. Fifty-three bisulfite-modified DNA samples were assessed through methyl-sensitive high-resolution melting (MS-HRM) analysis. To validate the results, we directly sequenced MS-HRM samples to confirm the presence of CpG-methylated positions. In addition, the RXRα protein levels in extracts of umbilical vein blood were evaluated by western blot. We found differential methylation in a specific locus of the RXRα promoter surrounding the EGR-binding sequence; however, no correlation was found with the level of RXRα protein expression. Variability in the methylation status of the RXRα promoter near the EGR transcription factor binding site in newborn cord blood provides controversial epigenetic insights into RXRα regulation via EGR proteins.

DNA methylation and regulation of gene expression: Guardian of our health

“…Igf2/H19 ICR methylation levels and consequent gene expression regulations have been correlated with cerebellar weight [ 68 ] and subcutaneous adiposity [ 38 ]. Furthermore, there has been evidence that maternal diet influences the methylation pattern of the CpG rich promoters of Retinoid X Receptor Alpha (RXRα) gene, thereby regulating metabolism levels in the offspring [ 9 ]. Interesting correlations have been established between the methylation levels at the loci of oxytocin receptor (OXTR) and social and emotional behaviour of humans [ 64 ].…”

Influence of pre-pregnancy body mass index (p-BMI) and gestational weight gain (GWG) on DNA methylation and protein expression of obesogenic genes in umbilical vein

“…Nutritional status of pregnant woman is a major environmental contributor for fetal development and many studies have used p-BMI and/or GWG during pregnancy as indicators of the adequacy of the nutritional status [33,34]. We previously reported the use of these indirect indicators of maternal health in the assessment of differential methylation in newborns of a diet-responsive gene [35]. The current study aimed to explore whether maternal p-BMI and GWG are associated with a single-locus promoter methylation of GNPDA2 , PGC1α and LEPR genes and their consequent protein expression in newborns.…”

Sex-differential RXRα gene methylation effects on mRNA and protein expression in umbilical cord of the offspring rat exposed to maternal obesity

“…Initial identification of the sequences was made after performing BLAST searches of the NCBI database. The electropherogram quality was visualized with BioEdit Sequence Alignment Editor software v7.2.5, and CpG highlighting was simplified using the BiQ Analyzer software tool ( Chávez-Lizárraga et al, 2018 ).…”

“…Interestingly, the DNA-binding element for early growth response (EGR) proteins in the promoter region of the retinoid X receptor alpha (RXRα) gene is susceptible to differential DNA methylation (Chávez-Lizárraga et al, 2018).…”

“…Early growth response-1 (EGR-1) protein induces inflammatory cytokines expression in the trophoblast ( Saben et al, 2013 ). Interestingly, the DNA-binding element for early growth response (EGR) proteins in the promoter region of the retinoid X receptor alpha (RXRα) gene is susceptible to differential DNA methylation ( Chávez-Lizárraga et al, 2018 ).…”