Genetic imprinting of H19 and IGF2 in domestic pigs (Sus scrofa)

The genes insulin-like growth factor 2 (IGF2) and H19 express paternally and maternally, respectively, in humans, mice, sheep, and cattle. Additionally, IGF2 has been shown to be regulated by at least four promoters in a tissue- or development-specific manner. In the domestic pigs, the promoter- and tissue-specific imprinting pattern of IGF2 has not been well characterized, nor is the imprinting pattern of H19. In the present study, we identified two polymorphisms in each of IGF2 (exons 2 and 9) and H19 (exons 1 and 5) and determined the imprinting status of these two genes in 13 organs / tissues of week-old pigs. IGF2 P1 transcript is bi-allelically expressed (not imprinted) in all major organs studied, while the majority of IGF2 transcripts are expressed from promoters 2-4 and are imprinted. H19 is exclusively expressed from the maternal allele in all major organs, concurrent with observations in other species.