Isolation of marmoset P450c17 cDNA and gene regulation in vitro

Marmosets express a fetal zone during adrenal development but fail to produce significant amounts of C19 steroids in adulthood. It is not clear however if P450c17 regulation is different from that in humans/rhesus or the primary sequence is altered. To this end we isolated marmoset and rhesus adrenocortical cells, and treated the cells with known regulators of P450c17 expression for 48 h. P450c17 protein increased with Forskolin (F) treatment, but was marginally inhibited by AII (A) and TPA (T) alone. Combined A + F and T + F dramatically ablated the F response. Cortisol levels (EIA) increased upon F treatment and were inhibited by A and T. Combination of treatments partially inhibited the F-induced response. The protein-coding region of marmoset and rhesus P450c17 cDNAs were then isolated from adrenals using RT-PCR/TA cloning. Marmoset P450c17 shows one amino acid deletion but otherwise shares 90.6% and 91.4% homologies with the human and rhesus cDNA sequences, and 82.4% and 85% homologies with the human and rhesus predicted AA sequences, respectively. Since marmoset adrenocortical cells exhibit similar endocrine function to rhesus, impaired 17,20-lyase activity in the adult marmoset adrenal may in part be due to differences in the primary sequence.