British Journal of Nutrition

Full Papers

Induction of altered epigenetic regulation of the hepatic glucocorticoid receptor in the offspring of rats fed a protein-restricted diet during pregnancy suggests that reduced DNA methyltransferase-1 expression is involved in impaired DNA methylation and changes in histone modifications

Karen A. Lillycropa1, Jo L. Slater-Jefferiesa2, Mark A. Hansona2, Keith M. Godfreya2a3, Alan A. Jacksona4 and Graham C. Burdgea2 c1

a1 Development and Cell Biology, Biomedical Sciences Building, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK

a2 Developmental Origins of Health and Disease Division, University of Southampton, Princess Anne Hospital, Coxford Road, Southampton SO16 5YA, UK

a3 MRC Epidemiology Resource Centre, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK

a4 Institute of Human Nutrition, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK

Abstract

Prenatal nutritional constraint induces an altered metabolic phenotype in the offspring which in humans confers an increased risk of non-communicable disease. Feeding a protein-restricted (PR) diet to pregnant rats causes hypomethylation of specific gene promoters in the offspring and alters the phenotype. We investigated how altered epigenetic regulation of the hepatic glucocorticoid receptor (GR) 110 promoter is induced in the offspring. Rats were fed a control (180 g casein/kg) or a PR (90 g casein/kg) diet throughout pregnancy, and chow during lactation. Offspring were killed at postnatal day 34 (n 5 per maternal dietary group). Methylation-sensitive PCR showed that GR110 promoter methylation was 33 % lower (P < 0·001) and GR expression 84 % higher (P < 0·05) in the PR offspring. Reverse transcription–PCR showed that DNA methyltransferase-1 (Dnmt1) expression was 17 % lower (P < 0·05) in PR offspring, while Dnmt3a/b and methyl binding domain protein-2 expression was not altered. Thus hypomethylation of the GR110 promoter may result from lower capacity to methylate hemimethylated DNA during mitosis. Histone modifications which facilitate transcription were increased at the GR110 promoter (147–921 %, P < 0·001), while those that suppress methylation were decreased (54 %, P < 0·01) or similar to controls. In human umbilical cord (n 15), there was a 2-fold difference between the highest and lowest level of GR1-CTotal promoter methylation. Dnmt1, but not Dnmt3a, expression predicted 49 % (P = 0·003) of the variation in GR1-CTotal promoter methylation. These findings suggest that induction in the offspring of altered epigenetic regulation of the hepatic GR110 promoter, and hence metabolic phenotype, may be due to reduced Dnmt1 expression.

(Received July 14 2006)

(Revised December 12 2006)

(Accepted December 18 2006)

Correspondence:

c1 *Corresponding author: Dr G. C. Burdge, fax +44 (0) 23 80594379, email g.c.burdge@soton.ac.uk

Footnotes

Abbreviations: ChIP, chromatin immunoprecipitation; Dnmt, DNA methyltansferase; GR, glucocorticiod receptor; HDAC, histone deacetylase; HMT, histone methyltransferase; MBD, methyl binding domain protein; MeCP2, methyl CpG-binding protein; PEPCK, phosphoenolpyruvate carboxykinase; PPAR, peroxisomal proliferator-activated receptor; PR, protein restricted; RT–PCR, reverse transcription–PCR; UC, umbilical cord

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