TSH-induced differentiated functions correlate with enhancement of phosphotyrosine phosphatase activity in thyroid cells. Effect of phorbol 12-myristate 13-acetate.
TSH-treated pig thyroid cells reorganize into follicle-like structures and exhibit differentiated functions. TSH also induces a phosphotyrosine phosphatase (PTPase) activity evaluated by phosphorylated substrate hydrolysis. Incubation of thyrocytes with various concentrations of 8-bromo-cyclic AMP or forskolin induces an increase of PTPase activity in a dose-dependent manner. During the culture period, adenylyl cyclase sensitivity, protein binding iodine and PTPase activity progressively increase from the first to the fourth day of the culture. Chronic treatment with phorbol 12-myristate 13-acetate (PMA) significantly inhibits PTPase activity during the first 24 h following PMA addition. GF 109203X, a specific inhibitor of protein kinase C, abolishes the inhibitory effect of PMA. Electrophoresis of membrane extracts allowed us to demonstrate a phosphatase activity at 111 kDa (p111). Vanadate inhibits this activity, indicating that p111 is a PTPase. This p111 is significantly reduced in PMA-treated cells. These data suggest that PTPase activity evidenced at 111 kDa is correlated with a differentiated state of primary cultured pig thyroid cells induced by TSH.
Petitfrère
E
E
Université de Reims Champagne Ardenne-IFR 53 Biomolécules, Laboratoire de Biochimie, FRE CNRS 2260, UFR Sciences, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France. emmanuelle.petitfrere@univ-reims.fr
Huet
E
E
Sartelet
H
H
Martiny
L
L
Legue
O
O
Haye
B
B
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007455:Iodine / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D017027:Protein Tyrosine Phosphatases / Q000187:drug effects / Q000378:metabolism*; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D013972:Thyrotropin / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D013972:Thyrotropin; D007455:Iodine; D000242:Cyclic AMP; D011493:Protein Kinase C; D017027:Protein Tyrosine Phosphatases; D000262:Adenylyl Cyclases; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate