IGF2 antisense transcript expression in porcine postnatal muscle is affected by a quantitative trait nucleotide in intron 3

A paternally expressed quantitative trait locus (QTL) for muscle mass was mapped to the insulin-like growth factor II ( IGF2) locus at the distal end of pig chromosome 2p. It was recently demonstrated that a G to A transition at position intron 3–nt 3072 is the quantitative trait nucleotide (QTN) underlying this QTL. In this study we report for the first time the existence of imprinted porcine IGF2 antisense transcripts ( IGF2-AS) and demonstrate that their expression in postnatal muscle is also affected by the QTN. A coregulated expression of IGF2 and IGF2-AS RNAs in muscle and liver with decreasing transcription from fetal to adult age was demonstrated. Further, the significant difference found in expression of IGF2-AS in postnatal muscle between individuals with different QTL genotypes and the lack of significant differences in fetal muscle and liver reflect completely what has been found for IGF2 sense transcripts.