The molecular structure and imprinting status of the IPW (imprinted gene in the Prader-Willi syndrome region) gene in cattle.

IPW (imprinted gene in the Prader-Willi syndrome region), a long non-coding RNA, is a paternally expressed gene in the PWS/AS imprinted domain on human chromosome 15 and mouse chromosome 7. Disruption of the PWS/AS region is associated with three neurogenic disorders in humans. In this study, we identified the bovine homolog of the IPW gene; multiple transcripts obtained by RT-PCR and RACE showed a complex and tissue-specific expression pattern of IPW in the brain, heart, kidney, liver, lung, spleen and skeletal muscle. An informative single nucleotide polymorphism (rs133341090) in the long exon H was identified by sequencing the genomic DNA, and mono-allelic expression of IPW was confirmed by sequencing the cDNAs of heterozygous individuals, indicating that IPW may be imprinted in cattle. The protein-coding potential of IPW transcripts was assessed using coding potential calculator (cpc) software, which showed a negative score. In addition, sequencing analysis also indicated multiple small open reading frames in the bovine IPW transcript, but none of the ATGs was consistent with Kozak consensus. Taken together, the IPW transcripts are most likely long non-coding RNAs.