Post-translational reduction of cell surface expression of insulin receptors by cyclosporin A, FK506 and rapamycin in bovine adrenal chromaffin cells.
Long-term (>/=3 h) treatment of cultured bovine adrenal chromaffin cells with cyclosporin A (CsA) decreased cell surface (125)I-insulin binding by 62% in a concentration (IC(50)=18 microM)- and time (t(1/2)=16 h)-dependent manner, but did not change the K(d) value. FK506 (1 microM) or rapamycin (3 microM) treatment reduced (125)I-insulin binding. Western blot analysis showed that CsA treatment decreased insulin receptor (IR) beta-subunit level (t(1/2)=15 h) in membrane fraction, but did not alter total cellular levels of IR precursor and IR beta-subunit. Internalization rate of cell surface IR measured by using brefeldin A, an inhibitor of vesicular exit from the trans-Golgi network, was comparable between non-treated and CsA-treated cells. Thus, CsA, FK506 and rapamycin inhibit peptidyl prolyl cis-trans isomerase activities of cyclophilin and FK506-binding protein, and down-regulate IR presumably by reducing cell surface externalization of IR.
Shiraishi
S
S
Department of Pharmacology, Miyazaki Medical College, Kiyotake, 889-1692, Miyazaki, Japan.
Yokoo
H
H
Kobayashi
H
H
Yanagita
T
T
Uezono
Y
Y
Minami
S
S
Takasaki
M
M
Wada
A
A
D000818:Animals; D015153:Blotting, Western; D020126:Brefeldin A / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism; D021983:Cyclophilins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D007457:Iodine Radioisotopes; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011972:Receptor, Insulin / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology*; D016559:Tacrolimus / Q000494:pharmacology*; D022021:Tacrolimus Binding Proteins / Q000037:antagonists & inhibitors; D013995:Time
D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D007328:Insulin; D007457:Iodine Radioisotopes; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D016572:Cyclosporine; D011972:Receptor, Insulin; D021983:Cyclophilins; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus; D016559:Tacrolimus