Thyrotrophin-dependent desensitization by Chinese hamster ovary cells that express the recombinant human thyrotrophin receptor.
To determine whether thyrotrophin (TSH)-induced desensitization requires a thyroid-specific factor(s), the human TSH (hTSH) receptor was expressed in Chinese hamster ovary cells. The first incubation of the cells with TSH decreased the subsequent response of adenosine 3',5'-cyclic monophosphate to freshly added TSH in the second incubation. This homologous desensitization was observed as early as after 3 h of the first incubation. The lowest dose of TSH that elicited desensitization was 0.1 nmol/l. The desensitization was not overcome by adding higher doses of TSH in the second incubation. A 125I-labelled TSH-binding study revealed a decrease in the number of high-affinity binding sites but not in that of low-affinity binding sites. The data suggest that TSH-induced desensitization in hTSH receptor-transfected cells is caused, at least in part, by a decrease in the number of TSH receptors on the cell surface. The evidence demonstrates, contrary to an earlier report, that a thyroid-specific factor(s) is not required for hTSH receptor desensitization.
Haraguchi
K
K
Third Department of Internal Medicine, University of Yamanashi Medical School, Japan.
Peng
X
X
Kaneshige
M
M
Anzai
E
E
Endo
T
T
Onaya
T
T
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D011989:Receptors, Thyrotropin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism* / Q000494:pharmacology; D014162:Transfection
D011989:Receptors, Thyrotropin; D011994:Recombinant Proteins; D013972:Thyrotropin; D000242:Cyclic AMP