Reproduction Abstracts

Introduction: Maternal low protein diet exclusively during preimplantation mouse development (Emb-LPD) induces compensatory changes in extra-embryonic lineages including primitive endoderm (PE) to enhance nutrient delivery during later gestation, for example, stimulation of endocytosis. Whilst such responses protect fetal growth, adult offspring exhibit increased cardiometabolic disease risk. Here, we investigate epigenetic mechanisms underlying maternal dietary programming, using embryonic stem (ES) cell lines derived from Emb-LPD and control blastocysts to assess expression and histone epigenetic regulation of Gata-6 and Gata-4, lineage-specific transcription factors for PE differentiation.

Materials and methods: Mouse ES cell lines were derived from blastocysts from each diet treatment and used for embryoid body (EB) formation. qPCR, immunoblotting, fast chromatin immunoprecipitation (ChIP) and siRNA protocols were undertaken with appropriate normalisation and technical controls.

Results and discussion: Emb-LPD EBs with outer PE proliferate to larger diameter than control EBs. Gata-6 down-regulation is known to stimulate proliferation and reduce differentiation in cancer and cardiomyocyte models. Gata-6 mRNA and protein expression are down-regulated in Emb-LPD EBs and conceptus yolk sac with similar trend for Gata-4. ChIP analysis revealed Gata-6 promoter in Emb-LPD EBs was hypoacetylated for histone H3 and H4, reduced in H3K4Me3 and associated RNA polymerase II versus control EBs, all recognised mechanisms to suppress gene expression. Histone deacetylase (HDAC-1) expression was elevated in Emb-LPD EBs which may contribute to Gata-6 hypoacetylation and reduced expression, currently investigated by HDAC-1 siRNA manipulation. Our study indicates extra-embryonic lineage responses to maternal diet are mediated through epigenetic control of key transcription factors. Funding: BBSRC BB/1001840/1.