Stillbirth risk on fat-1 transgenic foetus of sheep caused by deregulated DNA methylation of imprinted genes

Abstract

Imprinted genes play important roles on embryonic development. Aiming at the stillbirths in fat-1 transgenic foetuses of sheep, we detected the DNA methylation levels of candidate CpG regions in five imprinted genes (h19, igf2, igf2r, dlk1 and gtl2) of diverse tissues in the sheep foetuses, including both male and female fat-1 transgenic stillbirths of sheep and the wild live-births of sheep. Imprinted gene igf2, igf2r and dlk1 exhibited gender-neutral methylation except h19, which implies that the deregulated DNA methylation influenced by exogenous gene fat-1 in imprinted gene h19 more likely differs with gender. Besides, we found that exogenous gene fat-1 could tend to influence DNA methylation of imprinted gene igf2r in kidney of sheep male-foetus by comparing number of differentially methylated CpG sites. Since the bio-function of fat-1 on growth is consistent with h19 and igf2r, but opposite with igf2 and dlk1, we suggest that the stillbirth risk factors on sheep foetus with exogenous gene fat-1 should be focused on abnormal development (of organs or cells) that probably caused by deregulated methylation status of imprinted genes, and the deregulated methylation may be driven by conflicting and overlapped bio-function between exogenous gene and imprinted genes, rather than extrinsic source of gene. Abbreviations: CSF: control sheep female-foetuses; CSM: control sheep male-foetuses; HTLA: Humane Treatment of Laboratory Animals; n-3 PUFA(s): omega-3 polyunsaturated fatty acid(s); TSF: fat-1 transgenic sheep-stillbirths of female; TSM: fat-1 transgenic sheep-stillbirths of male

Keywords

• fat-1 transgenic foetus
• sheep
• imprinted gene
• methylation
• development