Modification of epigenetic patterns in low birth weight children: importance of hypomethylation of the ACE gene promoter.

Marina Rangel,Daniela Filippini Ierardi,Miriam Galvonas Jasiulionis,Maria Do Carmo Franco,Ronaldo C Araujo,Paula Helena Lima Ortiz,Mario Hirata,Jéssica Cassilla Dos Santos,Christopher Torrens

doi:10.1371/journal.pone.0106138

Abstract

There is a growing body of evidence that epigenetic alterations are involved in the pathological mechanisms of many chronic disorders linked to fetal programming. Angiotensin-converting enzyme (ACE) appears as one candidate gene that brings new insights into the epigenetic control and later development of diseases. In this view, we have postulated that epigenetic modifications in the ACE gene might show different interactions between birth weight (BW), blood pressure levels, plasma ACE activity and ACE I/D polymorphism. To explore this hypothesis, we performed a cross-sectional study to evaluate the DNA methylation of 3 CpG sites using pyrosequencing within the ACE gene promoter of peripheral blood leukocytes from 45 LBW children compared with 70 NBW children. Our results have revealed that LBW children have lower methylation levels (P<0.001) in parallel with a higher ACE activity (P = 0.001). Adjusting for prematurity, gender, age, body mass index, and family history of cardiovascular disease did not alter these findings. We have also performed analyses of individual CpG sites. The frequency of DNA methylation was significantly different at two CpG sites (site 1: nucleotide position +555; and site 3: nucleotide position +563). In addition, we have found a significant inverse correlation between degree of DNA methylation and both ACE activity (P<0.001) and systolic blood pressure levels (P<0.001). We also observed that the methylation level was significantly lower in LBW children who are carriers of the DD genotype compared to NBW children with DD genotype (P<0.024). In conclusion, we are able to demonstrate that the hypomethylation in the 3 CpG sites of ACE gene promoter is associated with LBW in 6 to 12 year-old children. The magnitude of these epigenetic changes appears to be clinically important, which is supported by the observation that discrete changes in DNA methylation can affect systolic blood pressure and ACE protein activity levels.

Highlights

Epigenetic programming refers to alterations in gene expression which are not explained by changes in the DNA sequence itself
Children with a history of low birth weight (LBW) showed higher blood pressure levels when compared with those born with a normal weight; Angiotensin-converting enzyme (ACE) protein activity levels were significantly elevated in these children (Table 1)
Among the LBW children, 58% were below the 50th percentile for DNA methylation in ACE gene promoter and 18% remained below the 10th percentile

Summary

Introduction

Epigenetic programming refers to alterations in gene expression which are not explained by changes in the DNA sequence itself. The role of DNA methylation has been studied recently in experimental models of fetal programming, suggesting that epigenetic aspects are an important link between the intrauterine environment and the risk for developing chronic diseases in later life [7,8,9,10,11,12]. DNA methylation occurs primarily at cytosines in cytosine-guanine dinucleotides (CpG) [13,14]. There are regions of DNA sequence that are very rich in CpG dinucleotides, termed CpG islands which primarily occur in gene promoter regions. An interesting characteristic of many genes (,60%) is that they have a CpG island at the 59 end of the promoter region which is important for transcriptional regulation [13,14]

Methods

Results

Conclusion