Cytochrome P4502B follows a vesicular route to the plasma membrane in cultured rat hepatocytes.
OBJECTIVE
Autoantibodies against cytochrome P450 are found in some forms of autoimmune hepatitis. Cytochrome P450 is synthesized and mainly located in the endoplasmic reticulum but may also be expressed on the plasma membrane of hepatocytes. Vesicles migrate from the endoplasmic reticulum to the Golgi apparatus and then to the plasma membrane along microtubules. We determined the route followed by cytochrome P4502B to reach the plasma membrane.


METHODS
Rat hepatocytes were cultured for 2 hours after plating with various inhibitors of cellular trafficking. Detached, uncut, nonpermeabilized hepatocytes were then exposed to a monoclonal antibody specific for cytochrome P4502B and studied by flow cytometry and confocal microscopy.


RESULTS
The plasma membrane expression of cytochrome P4502B was markedly decreased after 2 hours of culture with cycloheximide (an inhibitor of protein synthesis), caffeine at 20 degrees C (conditions that decrease vesicular transport from the endoplasmic reticulum to the Golgi apparatus), brefeldin A (which redistributes Golgi components back to the endoplasmic reticulum), monensin (an inhibitor of Golgi functions), and colchicine, vinblastine, or nocodazole (three microtubule inhibitors).


CONCLUSIONS
Part of cytochrome P4502B follows a microtubule-dependent vesicular route from the endoplasmic reticulum to the plasma membrane in cultured rat hepatocytes.
Robin
M A
MA
INSERM Unité 24, Hôpital Beaujon, Clichy, France.
Maratrat
M
M
Loeper
J
J
Durand-Schneider
A M
AM
Tinel
M
M
Ballet
F
F
Beaune
P
P
Feldmann
G
G
Pessayre
D
D
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000201:enzymology; D004790:Enzyme Induction / Q000187:drug effects; D005434:Flow Cytometry; D002479:Inclusion Bodies / Q000201:enzymology; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008297:Male; D018613:Microscopy, Confocal; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013250:Steroid Hydroxylases / Q000096:biosynthesis / Q000378:metabolism*
D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C025619:steroid 16-beta-hydroxylase; D010634:Phenobarbital