Evaluation of coding-independent functions of the transcribed bovine aromatase pseudogene CYP19P1

CYP19A1 encodes the aromatase which catalyzes the final reaction of estrogen biosynthesis. The bovine genome also contains a non-coding copy of CYP19A1, the transcribed pseudogene CYP19P1. Whereas CYP19A1 is transcribed in all estrogen-producing tissues, mainly in the placenta and gonads, the CYP19P1 transcript so far was detected in the placenta. Strikingly, one sequence segment of both transcripts exhibits an exceptional high identity of 98%, which implies selective pressure and suggests some kind of function. Only recently, indeed, coding-independent functions of several transcribed pseudogenes were reported. Therefore, we analyzed CYP19P1 and CYP19A1 transcripts with the aim to detect clues for gene-pseudogene interference.

The CYP19P1 transcript was first examined in silico for the presence of microRNA coding sequences and microRNA targets. Further, to identify tissues where CYP19P1 and CYP19A1 transcripts are co-expressed, as a pre-requisite for transcript interference, expression profiling was performed in a variety of bovine tissues. Our in silico analyses did neither reveal potential microRNA coding sequences, nor microRNA targets. Co-expression of the CYP19 loci was demonstrated in placental cotyledons and granulosa cells of dominant follicles. However, in granulosa cells of dominant follicles the concentration of CYP19P1 mRNA was very low compared to CYP19A1 mRNA.

CYP19P1 and CYP19A1 transcripts might interfere in placental cotyledons. However, in granulosa cells of dominant follicles relevant interference between gene and pseudogene transcripts is unlikely to occur because of the very low CYP19P1/CYP19A1 transcript ratio.