The tertiary structures of porcine AhR and ARNT proteins and molecular interactions within the TCDD/AhR/ARNT complex.
The aryl hydrocarbon receptor (AHR) is an intracellular transcription factor best known for mediating the toxicity of dioxins. The AHR is phylogenetically highly conserved among invertebrates and vertebrates and may play a significant role in the regulation of physiological processes including female reproduction. This study was performed to determine the partial nucleotide sequence of porcine AHR and to evaluate the AHR mRNA (real-time PCR) and AHR protein (Western blot) expression in granulosa and theca interna cells harvested from medium (3-6 mm) and pre-ovulatory (≥8 mm) follicles as well as in luteal cells obtained from corpora lutea collected during the mid-luteal phase (days: 8-10) of the porcine oestrous cycle. In the study, the partial nucleotide sequence of porcine AHR containing 1021 bp (GenBank accession no: HM488957.1) was determined. The AHR transcript and protein were found in all ovarian cells obtained during both phases of the porcine oestrous cycle. The highest AHR transcript level was detected in theca interna cells isolated from pre-ovulatory follicles as well as in luteal cells. Higher AHR protein expression was found in granulosa cells isolated from pre-ovulatory follicles in comparison with all remaining cell types. The presence of AHR in the examined ovarian cells may account for their sensitivity to some environmental pollutants. Moreover, the differences found in AHR mRNA expression between granulosa and theca cells as well as between cells originating from follicles of different size suggest the involvement of AHR in the modulation of reproductive processes in the porcine ovary.