Vesicular transport of newly synthesized cytochromes P4501A to the outside of rat hepatocyte plasma membranes.
نویسندگان
چکیده
Anti-cytochrome P450 (CYP)1A2 autoantibodies are found in dihydralazine-induced hepatitis, and CYPs2B and 2C have been shown to follow vesicular flow to the plasma membrane (PM). However, it is unknown whether other CYPs follow this route, whether NADPH-CYP reductase is present on the hepatocyte surface, and whether autoimmune hepatitis-inducing drugs increase PM CYPs. In this study, we determined the transmembrane topology and transport of CYPs1A in rat hepatocytes. In cultured hepatocytes, colchicine and other vesicular transport inhibitors decreased PM CYPs1A assessed by flow cytometry. Colchicine administration also decreased PM CYPs1A in vivo. Pulse chase experiments with [(35)S]methionine showed that only the newly synthesized CYP molecules are transferred to the PM, whereas microsomal CYP1A2 was stably radiolabeled for several hours. In contrast, radiolabeled CYP1A2 reached the PM and disappeared from the PM with half-lives of less than 30 min. Confocal microscopy, biotinylation, and coimmunoprecipitation experiments showed that PM CYPs1A and CYP reductase are present on the cell surface, and that the reductase is closely associated with PM CYPs. Exposure of whole cells to an anti-CYP1A1/2 antibody at 4 degrees C, before five washes and PM preparation, abolished PM CYPs1A-supported monooxygenase activity, indicating that PM CYPs are mostly located on the external surface. Dihydralazine and other CYPs1A inducers increased PM CYPs1A. In conclusion, newly synthesized CYPs1A follow vesicular flow to the outside of the PM, and NADPH-CYP reductase also is located on the hepatocyte surface. Dihydralazine administration increases PM CYP1A2, its autoimmune target.
منابع مشابه
Transport of newly synthesized vesicular stomatitis viral glycoprotein to purified Golgi membranes
In a previous communication we reported that the newly synthesized membrane glycoprotein of vesicular stomatitis virus could be transported in crude extracts of CHO cells from endoplasmic reticulum-derived membranes to membranes of the Golgi complex. This conclusion was an indirect one, based on the terminal glycosylation of this glycoprotein, a reaction that was dependent upon a Golgi-specific...
متن کاملEfficient trafficking of MDR1/P-glycoprotein to apical canalicular plasma membranes in HepG2 cells requires PKA-RIIalpha anchoring and glucosylceramide.
In hepatocytes, cAMP/PKA activity stimulates the exocytic insertion of apical proteins and lipids and the biogenesis of bile canalicular plasma membranes. Here, we show that the displacement of PKA-RIIalpha from the Golgi apparatus severely delays the trafficking of the bile canalicular protein MDR1 (P-glycoprotein), but not that of MRP2 (cMOAT), DPP IV and 5'NT, to newly formed apical surfaces...
متن کاملمهار ترشح تری اسیل گلیسرول وابسته به فراکسیون VLDL توسط اگونیست های آلفا- و بتا- ادرنوسپور در هپاتوسیت تهیه شده از کبد رت (Rat)
Background and purpose: Ât hunge state liver is the main source of synthesizing and secretion of low Density Lipoprotein (KLDL). For this purpose triacyleglycerol, phospholipids, cholestrol and its esters must be added to newly synthesized Âpo-B and secreted as a newly synthesized VLDL.VLDH metabolism is under hormonal and metabolic control, and stimulation of both ways is dependent on calciu...
متن کاملCholesterol and vesicular stomatitis virus G protein take separate routes from the endoplasmic reticulum to the plasma membrane.
Transport of newly synthesized cholesterol and vesicular stomatitis virus G protein from the endoplasmic reticulum to the plasma membrane is interrupted by incubation at 15 degrees C. Under this condition the newly synthesized molecules accumulate in both the endoplasmic reticulum (ER) and a subcellular vesicle fraction of low density called the lipid-rich vesicle fraction. The material in the ...
متن کاملKinetics of intracellular transport and sorting of lysosomal membrane and plasma membrane proteins
We have used monospecific antisera to two lysosomal membrane glycoproteins, lgp120 and a similar protein, lgp110, to compare the biosynthesis and intracellular transport of lysosomal membrane components, plasma membrane proteins, and lysosomal enzymes. In J774 cells and NRK cells, newly synthesized lysosomal membrane and plasma membrane proteins (the IgG1/IgG2b Fc receptor or influenza virus he...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of pharmacology and experimental therapeutics
دوره 294 3 شماره
صفحات -
تاریخ انتشار 2000