Biallelic transcription of the porcine IGF2R gene.

Here we report biallelic IGF2R gene expression in pig. We investigated SNPs in IGF2R exon 37 and in the 3'UTR and found biallelic expression in fetal brain and in livers, muscle and kidney tissues of fetal, newborn and adult pigs. PCR-RFLP and DNA sequencing results show consistently that IGF2R is expressed from both parental alleles although differential allelic expression may occur. The CpG island around IGF2R exon 1 was hypomethylated in all studied tissues and development stages. The CpG island in IGF2R intron 2 was hemimethylated in all studied tissues of fetal, newborn and adult pigs where the maternal allele was hypermethylated. It is therefore a differentially methylated region (DMR) by definition. RT-PCR showed no evidence for AIR transcription. A blast analyses revealed ESTs from intron 1 in sense direction, which are likely internally primed transcript artifacts. We suggest that porcine IGF2R expression widely resembles that of the human ortholog.