Effect of pregnancy on cytochrome P450 3a and P-glycoprotein expression and activity in the mouse: mechanisms, tissue specificity, and time course.

ABSTRACT The plasma concentrations of orally administered anti-human immunodeficiency virus protease inhibitors are significantly reduced during human and mouse pregnancy. We have shown that in the mouse, at gestational day 19, this reduction is due to increased hepatic cytochrome P450 3a (Cyp3a) protein expression and activity. In the current study, we investigated the mechanisms by which Cyp3a activity is increased by pregnancy and the time course of change in expression of Cyp3a and P-glycoprotein (P-gp) in various tissues. We found that hepatic transcripts of Cyp3a16, Cyp3a41, and Cyp3a44 were significantly increased during pregnancy, whereas those of Cyp3a11 and Cyp3a25 were significantly decreased. This resulted in a net increase in Cyp3a protein expression and activity in the liver during pregnancy. The increase in Cyp3a41 and Cyp3a44 transcripts was positively correlated (p Ͻ 0.05) with hepatocyte nuclear factor 6 and estrogen receptor-␣ transcripts. The pregnancy-related factors that transcriptionally activated mouse Cyp3a isoforms also activated the human CYP3A4 promoter in pregnant CYP3A4-promoter-luciferase transgenic (CYP3A4-tg) mice. In contrast, intestinal Cyp3a protein expression was not significantly affected by pregnancy. No change in P-gp protein expression was observed in the liver or kidney during pregnancy, although a significant decrease was observed in the placenta. Because hepatic CYP3A activity also seems to be induced during human pregnancy, the mouse (including CYP3A4-tg mouse) seems to be an excellent animal model to determine the molecular mechanisms for such an induction. To treat the pregnant woman and to prevent maternalfetal HIV-1 transmission, HIV-1-infected pregnant women are routinely prescribed anti-HIV protease inhibitors as part of their highly active antiretroviral therapy regimen The bioavailability and systemic clearance of the PIs are primarily determined by the drug-metabolizing enzymes cytochrome P450 3A4/5 (CYP3A4/5) and the drug efflux transporter P-glycoprotein (P-gp) in the small intestine and live

Transporter Expression in Liver Tissue from Subjects with Alcoholic or Hepatitis C Cirrhosis Quantified by Targeted Quantitative Proteomics

ABSTRACT Although data are available on the change of expression/activity of drug-metabolizing enzymes in liver cirrhosis patients, corresponding data on transporter protein expression are not available

Residues Met89 and Ser160 in the Human Equilibrative Nucleoside Transporter 1 (hENT1) Affect hENT1's Affinity for Adenosine, Guanosine, NBMPR and

Abstract The human equilibrative nucleoside transporter 1 (hENT1) is an important modulator of the physiological action of adenosine. We identified amino acid residues involved in adenosine transport using a yeast-based assay to rapidly screen and identify randomly generated hENT1 mutants that exhibited decreased sensitivity to inhibition of adenosine transport by various hENT1 competitive inhibitors. We identified Met89 and alone. Collectively, these data indicate that TMD2 (Met89) and TMD4 (Ser160) of hENT1 interact and are important in conferring sensitivity to NBMPR. In contrast, Ser160 and Met89 of hENT1 respectively play a dominant role in conferring sensitivity to dipyridamole and adenosine/guanosine affinity

Prediction of Gestational Age-Dependent Induction of In Vivo Hepatic CYP3A Activity Based on HepaRG Cells and Human Hepatocytes Running Title: Prediction of Gestational Age-Dependent Induction of In Vivo Hepatic CYP3A Activity

ABSTRACT In pregnant women, CYP3A activity increases by 100% during the third trimester (T3). Due to logistical and ethical constraints, little is known about the magnitude of CYP3A induction during the first (T1) and second (T2) trimesters. Our laboratory has shown that sandwich-cultured human hepatocytes (SCHH) and HepaRG cells have the potential to predict the magnitude of in vivo induction of CYP3A activity likely to be observed in T1 and T2. Therefore, we incubated SCHH and HepaRG cells with plasma concentrations of various pregnancy-related hormones (PRHs, individually or in combination) observed during T1, T2, or T3 in pregnant women. Then, Based on these data, we conclude that C remains the major inducer of CYP3A activity earlier in gestation. Moreover, we predict that the magnitude of CYP3A induction during T1 and T2 will be similar to that observed during T3 (~100% increase vs. postpartum). This prediction is consistent with the observation of similar increase in T2 and T3 oral clearance of indinavir (a CYP3A cleared drug) vs. postpartum