The peptidyl-prolyl cis/trans isomerase (PPIase) activity and the expression of cyclophilins were studied in 6-day-old rabbit preimplantation embryos cultured under physiological and increased oxygen concentrations of 5% and 20% O2, respectively. The PPIase activity was completely inhibited by cyclosporin A (CsA). The inhibitor of FK506-binding proteins, rapamycin, had no effect on the PPIase activity, indicating that the PPIase activity in rabbit blastocysts originates from cyclophilins. Using CsA affinity chromatography, only one cyclophilin with a molecular mass of about 17.8 kDa was separated. The cDNA of rabbit cyclophilin was cloned and sequenced. Analysis of the 682-base pair cDNA revealed an open reading frame coding for a polypeptide of 164 amino acid residues with a molecular weight of 17.83 kDa. Homologies of 90% and 96% for the cDNA and amino acid sequence, respectively, to the human CyP18 were found, suggesting that the novel rabbit cyclophilin is a member of the CyP18 family (rabCyP18). The transcription level of rabCyP18 mRNA was 8.3 ± 0.6 pg in 100 ng total RNA in noncultured blastocysts. In vitro culture with moderate oxygen stress (20% O2) resulted in a 1.5-fold increase in rabCyP18 transcription and an increased PPIase activity compared to that of blastocysts cultured with 5% O2. Increase in transcription rate and PPIase activity by oxygen stress suggests an involvement of CyP18 in oxygen defense in rabbit preimplantation embryos.
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1 January 2000
Oxygen Stress Increases Prolyl cis/trans Isomerase Activity and Expression of Cyclophilin 18 in Rabbit Blastocysts
Anne Navarrete Santos,
Sabine Körber,
Gerd Küllertz,
Gunter Fischer,
Bernd Fischer
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Biology of Reproduction
Vol. 62 • No. 1
January 2000
Vol. 62 • No. 1
January 2000