The hepatic Igf2/H19 locus is not altered in 1‐day old pups born to obese‐prone Sprague‐Dawley rats fed a low protein diet containing adequate folic acid

Abstract

Gong et al. (Epigenetics, 2010) found, using diets low in folic acid, that compared to an 18% protein diet a 9% protein diet fed to pregnant Sprague‐Dawley rats resulted in increased Igf2 and H19 gene expression in the liver of day 0 male offspring. In addition DNA methylation in the Imprinting Control Region (ICR) of the Igf2/H19 locus was significantly increased. The ICR contributes to controlling gene expression of the Igf2/H19 locus in a methylation‐dependent manner. We fed obese‐prone Sprague‐Dawley females an AIN‐93 based diet containing adequate folic acid and either 8% or 20% protein diet for 3 wk. They were then bred with chow‐fed obese‐prone males and fed their respective diets through pregnancy. At birth, litters were culled to 4 male and 4 female; each litter (by sex) was considered as N=1. At 1 day, weights (means±SD) were: 8% males, 5.15±0.42 (N=12); 20% males, 5.32±0.41 (N=13); 8% females, 4.74±0.62 (N=13); 20% females, 4.93±0.25 (N=13). Hepatic DNA methylation status of the ICR, which includes 4 CTCF binding sites, was determined by pyrosequencing. Real‐time PCR was used to determine liver mRNA expression (relative to Actin) of Igf2, H19 and methyl CpG‐binding domain 2 (Mbd2). Regardless of sex of the pups we found no effect of diet on DNA methylation status of the ICR or expression of Igf2, H19 or Mbp2. Thus, these results suggest that low protein by itself does not contribute to an alteration in the Igf2/H19 locus.