Project description:The constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) are closely related nuclear receptors involved in drug metabolism and play important roles in the mechanism of phenobarbital (PB)-induced rodent nongenotoxic hepatocarcino- genesis. Here, we have used a humanized CAR/PXR mouse model to examine potential species differences in receptor-dependent mechanisms underlying liver tissue molecular responses to PB. Early and late transcriptomic responses to sustained PB exposure were investigated in liver tissue from double knock-out CAR and PXR (CARKO -PXRKO ), double humanized CAR and PXR (CARh - PXRh), and wild-type C57BL/6 mice. Wild-type and CARh-PXRh mouse livers exhibited temporally and quantitatively similar tran- scriptional responses during 91 days of PB exposure including the sustained induction of the xenobiotic response gene Cyp2b10, the Wnt signaling inhibitor Wisp1, and noncoding RNA biomarkers from the Dlk1-Dio3 locus. Transient induction of DNA replication (Hells, Mcm6, and Esco2) and mitotic genes (Ccnb2, Cdc20, and Cdk1) and the proliferation-related nuclear antigen Mki67 were ob- served with peak expression occurring between 1 and 7 days PB ex- posure. All these transcriptional responses were absent in CARKO- PXRKO mouse livers and largely reversible in wild-type and CARh - PXRh mouse livers following 91 days of PB exposure and a subse- quent 4-week recovery period. Furthermore, PB-mediated upregu- lation of the noncoding RNA Meg3, which has recently been associ- ated with cellular pluripotency, exhibited a similar dose response and perivenous hepatocyte-specific localization in both wild-type and CARh-PXRh mice. Thus, mouse livers coexpressing human CAR and PXR support both the xenobiotic metabolizing and the proliferative transcriptional responses following exposure to PB. 13-week oral (drinking water) investigative phenobarbital study in male C57BL/6 wild type, CAR/PXR knockout and humanized CAR/PXR mice with a 4 week recovery period

Project description:The metabolic impact of the common peroxisome proliferator-activated receptor gamma isoform 2 (PPARÎ³2) variant Pro12Ala in human populations has been widely debated. We demonstrate using a Pro12Ala knock-in model that on chow Ala/Ala mice are leaner, have improved insulin sensitivity and plasma lipid profiles, and longer lifespan. Gene-environment interactions played a key role as high-fat feeding eliminated the beneficial effects of the Pro12Ala variant on adiposity, plasma lipids, and insulin sensitivity. The underlying molecular mechanisms involve changes in cofactor interaction and adiponectin signaling. Altogether, our results establish the Pro12Ala variant of PparÎ³2 as an important modulator in metabolic control that strongly depends on the metabolic context. PparÎ³ Pro12Ala and wild-type littermates were fed regular rodent chow or high-fat diet (D12330, 5560 kcal/kg, Research Diets, New Brunswick, NJ), as indicated. Only males were used to minimize possible effects of variation in estrus status of females. Since the body weight development of Pro/Ala heterozygote mice was intermediate to that of Pro/Pro and Ala/Ala mice, we focused on the two homozygote genotypes in further experimentation. Mice were housed with a 12h light-dark cycle and had free access to water and food. Eight week old male Pro/Pro and Ala/Ala littermate mice were fed either regular rodent chow or high-fat diet (as above) for 15 weeks (n = 8-10 per group), at which time blood and tissue samples were collected. Total RNA extraction, sample amplification, labeling, and microarray (Genechip Mouse Genome 430 2.0 Array, Affymetrix Inc., Santa Clara, CA) processing steps were performed by the Rosetta Inpharmatics Gene Expression Laboratory (Seattle, WA) using custom automated procedures in compliance with manufacturer protocols. Microarray data was processed using Rosetta Resolver (Rosetta Inpharmatics, Seattle, WA) and expressed as relative to the virtual pool of HFD â Pro/Pro group (mlratio). Gene expression signatures were generated from these mlratios for expressed genes (25% of RMA processed intensities above 60% quantile) by T-testing (Pro/Pro vs. Ala/Ala) and correcting for multiple testing (20% cut-off for False Discovery Rate). GSEA was performed according to provider suggestions, Pro/Pro vs. Ala/Ala. Statistical significance was declared if P < 0.05.

Project description:The constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) are closely related nuclear receptors involved in drug metabolism and play important roles in the mechanism of phenobarbital (PB)-induced rodent nongenotoxic hepatocarcino- genesis. Here, we have used a humanized CAR/PXR mouse model to examine potential species differences in receptor-dependent mechanisms underlying liver tissue molecular responses to PB. Early and late transcriptomic responses to sustained PB exposure were investigated in liver tissue from double knock-out CAR and PXR (CARKO -PXRKO ), double humanized CAR and PXR (CARh - PXRh), and wild-type C57BL/6 mice. Wild-type and CARh-PXRh mouse livers exhibited temporally and quantitatively similar tran- scriptional responses during 91 days of PB exposure including the sustained induction of the xenobiotic response gene Cyp2b10, the Wnt signaling inhibitor Wisp1, and noncoding RNA biomarkers from the Dlk1-Dio3 locus. Transient induction of DNA replication (Hells, Mcm6, and Esco2) and mitotic genes (Ccnb2, Cdc20, and Cdk1) and the proliferation-related nuclear antigen Mki67 were ob- served with peak expression occurring between 1 and 7 days PB ex- posure. All these transcriptional responses were absent in CARKO- PXRKO mouse livers and largely reversible in wild-type and CARh - PXRh mouse livers following 91 days of PB exposure and a subse- quent 4-week recovery period. Furthermore, PB-mediated upregu- lation of the noncoding RNA Meg3, which has recently been associ- ated with cellular pluripotency, exhibited a similar dose response and perivenous hepatocyte-specific localization in both wild-type and CARh-PXRh mice. Thus, mouse livers coexpressing human CAR and PXR support both the xenobiotic metabolizing and the proliferative transcriptional responses following exposure to PB. 13-week oral (drinking water) investigative phenobarbital study in male C57BL/6 wild type, CAR/PXR knockout and humanized CAR/PXR mice with a 4 week recovery period

Dataset Information

Microarray analysis of the migrating human CD4+ T cell population from the spleen of humanized mice in response to treatment with Teplizumab or hIg

Publications

Teplizumab induces human gut-tropic regulatory cells in humanized mice and patients.

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