The B subunit of cholera toxin enhances DNA synthesis in rat hepatocytes induced by insulin and epidermal growth factor.
The B subunit of cholera toxin, which binds to ganglioside GM1, enhanced DNA synthesis in rat hepatocytes in primary culture induced by insulin and/or epidermal growth factor. The effect was dose-dependent, and whole cholera toxin, activating adenylate cyclase, showed a higher effect than the B subunit alone. The B subunit acted additively with other agents that also increase cyclic AMP levels. A competitive antagonist of cyclic AMP could not suppress the effect of the B subunit completely. These data suggest that the effect is independent of the cyclic AMP signal pathway, and that GM1 plays a role in hepatocyte proliferation.
Mitsui
H
H
First Department of Internal Medicine, Faculty of Medicine, University of Tokyo.
Iwamori
M
M
Hashimoto
N
N
Yamada
H
H
Ikeda
Y
Y
Toda
G
G
Kurokawa
K
K
Nagai
Y
Y
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000008:administration & dosage / Q000494:pharmacology*; D000242:Cyclic AMP / Q000008:administration & dosage / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction
D007328:Insulin; D004815:Epidermal Growth Factor; D004247:DNA; D002772:Cholera Toxin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases