Autocrine biological effects of glycosyl inositol phosphate produced by reconstituted pig thyroid follicles: role of pertussis toxin sensitive G proteins.
We examine the autocrine activity of glycosyl inositol phosphate (InP-gly) on thyroid metabolism. The cAMP accumulation promoted by thyrotropin (TSH) or forskolin was modulated by InP-gly, stimulated by the lowest tested concentration (10(-8) M) and progressively inhibited by higher concentrations. Iodide uptake and iodine organification were decreased in a concentration-dependent manner by InP-gly alone, or in the presence of TSH. The IAP component of pertussis toxin blocked the inhibitory action of InP-gly on cAMP accumulation by reconstituted thyroid follicles (RTF), suggesting the participation of Gi protein. But the same treatment with IAP was without effect on iodine metabolism, suggesting that there is a second target for InP-gly, more distal than Gi protein, or coupled to another G protein which is insensitive to the toxin.
Martiny
L
L
Biochimie, Faculté des Sciences, Reims, France.
Delemer
B
B
Petitfrère
E
E
Lambert
B
B
Jacquemin
C
C
Haye
B
B
D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000502:physiology*; D006031:Glycosylation / Q000187:drug effects; D007295:Inositol Phosphates / Q000096:biosynthesis / Q000502:physiology*; D007454:Iodides / Q000378:metabolism; D007455:Iodine / Q000378:metabolism; D007700:Kinetics; D037342:Pertussis Toxin; D011485:Protein Binding; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D007295:Inositol Phosphates; D007454:Iodides; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D013972:Thyrotropin; D007455:Iodine; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins