Project description:Hepatic cell lines serve as economical and reproducible alternatives for primary human hepatocytes. However, the utility of hepatic cell lines to examine bile acid homeostasis and cholestatic toxicity is limited due to abnormal expression and function of bile acid-metabolizing enzymes, transporters, and the absence of canalicular formation. Previously, addition of dexamethasone (DEX) and Matrigel™ overlay restored expression, localization, and function of the bile salt export pump (BSEP), and formation of bile canalicular-like structures in four-week cultures of HuH-7 human hepatoma cells. We present here an improved differentiation process with the addition of 0.5% dimethyl sulfoxide (DMSO), which increased the expression and function of the major bile acid uptake and efflux transporters, sodium taurocholate co-transporting polypeptide (NTCP) and BSEP, respectively, in two-week HuH-7 cell cultures. This in vitro model was further characterized for expression of cytochrome P450 enzymes (CYP450s), uridine 5'-diphospho-glucuronosyltransferase (UGTs) and transporters using quantitative targeted proteomics.
Project description:Rotor syndrome is an autosomal recessive disorder characterized by conjugated hyperbilirubinemia, near-absent hepatic uptake of anionic diagnostics, and coproporphyrinuria. The mechanistic basis of other hyperbilirubinemia syndromes is largely understood, but that of Rotor syndrome has remained enigmatic. The existing paradigm of hepatic bilirubin excretion postulates a unidirectional elimination pathway: Uptake of conjugated bilirubin from blood by hepatocytes, glucuronidation of bilirubin, and excretion of conjugated bilirubin into bile by ABCC2, a canalicular bilirubin-glucuronide and xenobiotic export pump. An analogous view holds for drugs conjugated in the liver. Here we demonstrate by molecular-genetic analysis of 8 Rotor-syndrome families that Rotor syndrome is a two-gene disorder, with impaired hepatic re-uptake of bilirubin-glucuronide caused by complete deficiencies in the hepatic organic anion transporting polypeptides OATP1B1 and OATP1B3.
Project description:Rotor syndrome is an autosomal recessive disorder characterized by conjugated hyperbilirubinemia, near-absent hepatic uptake of anionic diagnostics, and coproporphyrinuria. The mechanistic basis of other hyperbilirubinemia syndromes is largely understood, but that of Rotor syndrome has remained enigmatic. The existing paradigm of hepatic bilirubin excretion postulates a unidirectional elimination pathway: Uptake of conjugated bilirubin from blood by hepatocytes, glucuronidation of bilirubin, and excretion of conjugated bilirubin into bile by ABCC2, a canalicular bilirubin-glucuronide and xenobiotic export pump. An analogous view holds for drugs conjugated in the liver. Here we demonstrate by molecular-genetic analysis of 8 Rotor-syndrome families that Rotor syndrome is a two-gene disorder, with impaired hepatic re-uptake of bilirubin-glucuronide caused by complete deficiencies in the hepatic organic anion transporting polypeptides OATP1B1 and OATP1B3. SNP genotyping was performed on 22 samples - 10 affected and 12 healthy siblings from 8 Rotor-syndrome families. Affymetrix GeneChip Command Console software was used for image processing and CEL files were processed by Affymetrix GTC using the BRLMM-P-Plus algorithm and regional GC correction configuration for Copy Number/LOH analysis. The HapMap270 file supplied by Affymetrix was used as the reference.
Project description:Mdr2 is the transporter of phosphatidylcholine, which is an essential component of bile. Deficiency of mdr2 causes hepatic inflammation, liver fibrosis and hepatocellular carcinoma. Mdr2-/- MEFs show increased proliferation, spontaneous transformation and tumorigenesis. We used microarray to obtain genome-wide profiling of gene expression underlying the changes in mdr2-/- MEFs.
Project description:Mdr2 is the transporter of phosphatidylcholine, which is an essential component of bile. Deficiency of mdr2 causes hepatic inflammation, liver fibrosis and hepatocellular carcinoma. Mdr2-/- MEFs show increased proliferation, spontaneous transformation and tumorigenesis. We used microarray to obtain genome-wide profiling of gene expression underlying the changes in mdr2-/- MEFs. MEFs derived from wt and mdr2-/- littermate embyos were subjected to passage according to 3T3 protocols. RNA was extracted from cells on passage 40 and hybridized on Affymetrix microarrays.
Project description:Metabolic-associated steatohepatitis is a progressive fatty liver disease caused, in part, by hepatocyte stress linked to cholesterol overload. Counteracting this stress may be beneficial but there is insufficient understanding of underlying stress defenses to develop a therapeutic strategy. Here, we aimed to elucidate how stress-adaptive transcription factors, nuclear factor erythroid 2 related factor-1 (NRF1) and -2 (NRF2), counteract hepatic cholesterol overload and determine whether they function cooperatively. C57bl/6 mice were fed high fat, fructose, and cholesterol diet (HFFC). Expression profiling and phenotypic analyses were done on liver of mice with adult-onset and hepatocyte-specific deficiency of NRF1, NRF2, or both, and results compared to control. Chromatin immunoprecipitation (ChIP) sequencing was done and combined with expression profiles to identify genes that NRF1 and NRF2 interact with and regulate in vivo. Three weeks HFFC diet feeding to mice with NRF1 and NRF2 deficiency caused severe steatohepatitis and increased hepatic cholesterol storage. These outcomes did not occur in single gene-deficient mice or control. Expression profiling at a time preceding hepatic cholesterol overload and ChIP sequencing profiling revealed complementary gene regulation by NRF1 and NRF2 to promote cholesterol excretion and mitigate hazardous metabolic biproducts generated from converting cholesterol to bile acid. Consequently, combined gene deficiency, and not single-gene deficiency, increased liver oxidized protein level, decreased cholesterol in bile, and increased unconjugated bile acid in liver and bile. We discover, for the first time, that NRF1 and NRF2 work together to protect liver against damaging effects of excess cholesterol. Targeting these combined actions may prove an effective therapeutic strategy
Project description:Chimeric mice with humanized livers are considered a useful animal model for predicting human drug metabolism and toxicity. In this study, the characteristics of fresh h-hepatocytes (cFHHs, PXB-cells®) isolated from chimeric mice (PXB-mice®) were evaluated in vitro to confirm their utility for drug development. The cFHHs cultured at high density (2.13 × 10^5 cells/cm2) displayed stable production of human albumin and cytochrome P450 (CYP) 3A activities for at least 21 days. The mRNA expression levels of 10 of 13 CYPs, UDP-glucuronosyltransferase (UGP), and transporters were maintained at >10% of the levels of freshly isolated cFHHs after 21 days. From 7-days cultured cFHHs at high density, many bile canaliculi were observed between cFHHs, and the accumulation of multidrug resistance-associated protein (MRP2) and bile salt export pump (BSEP) substrates in these bile canaliculi was clearly inhibited by cyclosporin A. We used microarrays to elucidate global gene expressions underlying this higher hepatic functions of high density cultured cFHHs (PXB-cells). Microarray analysis revealed that high density cultured cFHHs maintained high expressions of some transcription factors (HNF4α, PXR, and FXR) perhaps involved in the high CYP, UGT and transporter gene expressions of cFHHs.