Using expression cloning in Xenopus laevis oocytes, we have isolated a cDNA encoding rat liver organic anion-transporting polypeptide (oatp). The cloned oatp mediated Na(+)-independent uptake of sulfobromophthalein (BSP) which was Cl(-)-dependent the presence bovine serum albumin (BSA) at low BSP concentrations (e.g., 2 microM). Addition increasing amounts BSA had no effects on maximal velocity initial uptake, but it increased Km value from 1.5 microM (no BSA) to 24 (BSA/BSP molar ratio,...

Carrier-mediated prostaglandin transport has been postulated to occur in many tissues. On the basis of sequence homology, protein unknown function encoded by rat matrin F/G complementary DNA was predicted be an organic anion transporter. Expression HeLa cells or Xenopus oocytes conferred property specific prostaglandins. The tissue distribution messenger RNA and sensitivity F/G-induced inhibitors were similar those endogenous transport. is thus preferably called PGT because it likely as a

Rifampin, a member of the rifamycin class antibiotics, is well known for its ability to induce drug-metabolizing enzymes and transporters, through activation pregnane X receptor. Available data suggest rifampin entry into hepatocytes may be transporter-mediated. Accordingly, it therefore plausible that modulation achievable intracellular concentration by drug uptake transporters would influence degree induction. In this study, we expressed an array hepatic show key are liver-specific members...

The physiological mechanism of clearance the mononuclear phagocyte growth factor, colony-stimulating factor 1 (CSF-1), from circulation normal mice was investigated by following fate a trace amount i.v. injected 125I-labeled CSF-1. Macrophages selectively cleared CSF-1 receptor-mediated endocytosis and degraded intracellularly. This manner provides feedback control whereby rate macrophage production is determined number mature macrophages.

A Na(+)-independent organic anion transport protein was recently cloned from rat liver using a Xenopus laevis oocyte expression system [E. Jacquemin, B. Hagenbuch, Stieger, A.W. Wolkoff, and P.J. Meier, Proc. Natl. Acad. Sci. USA 91: 133-137, 1994]. Although of this is sufficient for cells to the bromosulfophthalein, little known about its cell biology or biochemical characteristics. Northern blot analysis performed under high-stringency conditions revealed hybridization with RNA only...

Rat hepatocytes in monolayer culture rapidly internalized asialoglycoproteins and the receptors to which they are bound. Subsequent endocytosis, receptor-ligand complex is dissociated within an acidic endosome (Harford, J., K. Bridges, G. Ashwell, R. D. Klausner, 1983, J. Biol. Chem. 258:3191-3197; Harford, A. W. Wolkoff, Cell 96:1824-1828). Here we show that addition of proton ionophore monensin cells after dissociation has occurred results intracellular rebinding ligand molecules. With...

Treatment of short-term monolayer cultures rat hepatocytes with the proton ionophore, monensin, abolishes asialoglycoprotein degradation, despite little effect drug on either surface binding ligand or internalization prebound ligand. Centrifuging cell homogenates Percoll density gradients indicates that, as a result monensin treatment, does not enter lysosomes but sediments instead in lower subcellular fraction that is likely an endocytic vesicle. Analyzing degree receptor association...

Multiple-indicator dilution studies of labeled bilirubin uptake were carried out on isolated perfused rat livers with variable ligandin concentrations (from normal and thyroidectomized animals without phenobarbital pretreatment). Ligandin concentrations, measured immunologically, increased 25% after thyroidectomy approximately doubled pretreatment but decreased to during perfusion in the nonpretreated group. A distributed two-compartment model was fitted data estimates influx, efflux,...

Somatic mutation levels in human liver increase with age and are higher differentiated hepatocytes than residential LSCs.

Organic anion transporting polypeptide (oatp) is an integral membrane protein cloned from rat liver that mediates Na+-independent transport of organic anions such as sulfobromophthalein and taurocholic acid. Previous studies in hepatocytes suggested uptake associated with base exchange. To better characterize the mechanism oatp-mediated uptake, we examined taurocholate a HeLa cell line stably transfected oatp under regulation zinc-inducible promoter (Shi, X., Bai, S., Ford, A. C., Burk, R....

The mechanisms involved in ethinyl estradiol-induced cholestasis are controversial. Basal bile flow was reduced by estradiol administration, with a half time (t1/2) of 12.5 +/- 0.6 h. In contrast, initial taurocholate uptake not significantly until 3 days to 59% control and 13 10% at 5 7 days, respectively. t1/2 4.3 0.1 days. These physiological changes were correlated measurement protein mass steady-state mRNA for Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase), Na(+)-dependent...

To characterize the transport functions of a recently cloned basolateral organic anion transporting polypeptide rat hepatocytes we performed further kinetic and substrate cis-inhibition studies in anion-transporting polypeptide—cRNA injected Xenopus laevis oocytes. The demonstrate saturable Na+-independent sulfobromophthalein (Michaelis-Menten constant, 1.5 μmol/L) taurocholate 50 uptake by polypeptide. Sulfobromophthalein was inhibited following anions: 0.01 mmol/L bilirubin (43%), 0.1...

Flavonoids are a class of polyphenolic compounds widely present in the diet and herbal products. The interactions flavonoids with some major efflux transporters [e.g., P-glycoprotein, multidrug resistance-associated protein 1 (MRP1), breast cancer resistance protein] have been reported; however, their uptake largely unknown. Organic anion-transporting polypeptide OATP1B1 is liver-specific transporter important hepatic drug disposition. Our objective was to evaluate effects 20 naturally...

The mRNA for organic anion transport protein (oatp) was previously shown to be present in abundance liver and kidney, small amounts brain. Data obtained from experiments with reverse transcriptase–PCR techniques situ hybridization analysis showed that the oatp is within brain, localized choroid plexus. A sequence-specific antibody polypeptide demonstrated presence of expected a molecular weight 80,000 plus an immunoreactive species higher preparations plexus membranes. Examination by...

Uptake of bilirubin, sulfobromophthalein (BSP), and other organic anions by the liver is a process with kinetics consistent carrier mediation. The molecular basis this transport mechanism unknown. In search for putative anion or receptor, interaction BSP rat cell plasma membrane (LPM) has been studied. Specific binding [35S]BSP to LPM was determined using filtration assay. Results revealed high affinity (Ka = 0.27 μM−1), saturable (6.3 nmol/mg protein) binding, which eliminated after...

Our previous studies demonstrated that fluorescent early endocytic vesicles prepared from rat liver after injection of Texas red asialoorosomucoid contain asialoglycoprotein and its receptor move undergo fission along microtubules using kinesin I KIFC2, with Rab4 regulating KIFC2 activity (J. Cell Sci. 116, 2749, 2003). In the current study, procedures to prepare late were devised. addition, flow cytometry was utilized highly purified vesicles, permitting validation microscopy-based...

Recently we expression cloned a rat liver organic anion transport protein in Xenopus laevis oocytes (Jacquemin, E. Hagenbuch, B, Stieger, B., Wolkoff, A.W., and Meier, P.J.,(1994) Proc. Natl. Acad. Sci. U.S.A. 91, 133-137). In the present study, have stably transfected cDNA encoding this into HeLa cells by using vector containing zinc-inducible promoter. The parent virtually no baseline of [35S]sulfobromophthalein, whereas induced express novel 74-kDa avidly ligand. Transport these is...

Transport of 35S-labeled sulfobromophthalein [35S]BSP was studied in short-term cultured rat hepatocytes incubated bovine serum albumin. At 37 degrees C, initial uptake 5-10-fold that at 4 linear for least 15 min, saturable, inhibited by bilirubin, and reduced greater than 70% after ATP depletion or isosmotic substitution sucrose NaCl medium. Replacement Na+ K+ Li+ did not alter uptake, whereas replacement Cl- HCO-3 gluconate- approximately 40%. Substitution the more permeant NO-3 enhanced...

Bilirubin uptake by the liver is a rapid process of high specificity that has kinetic characteristics which suggest carrier-mediation. In circulation, bilirubin readily bound to albumin, from it extracted liver. Although several studies suggested small, unbound fraction interacts with hepatocytes and removed recent experiments have been interpreted as suggesting binding albumin facilitates ligand uptake. A cell surface receptor for postulated. The present study was designed examine directly...

The normal rat hepatocyte divides approximately once per year but, following two thirds hepatectomy, rapid cellular replication occurs throughout the remaining liver remnant. Using a multiple indicator dilution technique, single-pass transport of 3 H-bilirubin and 125 I-asialoorosomucoid was studied in isolated perfused from 6hr to 6d after hepatectomy or sham surgery. Influx (k 1 ), efflux 2 sequestration ) rates were quantitated by computer analysis. k for fell over 50% within returned 4d...

Urinary total, isomer I, and III coproporphyrin excretion was determined in 16 patients with the Dubin-Johnson syndrome, 73 phenotypically normal family members, 20 unrelated controls of similar age. Normal subjects excreted 24.8 ± 1.3 per cent (mean S.E.M.) urinary as I. Patients syndrome 88.9 I (p less than 0.001). Twenty-five parents children 31.6 1.2 a value intermediate between results In 48 more distant relatives, percentage distributed over wide range. These indicate that, respect to...