Delemer B, Dib K, Saunier B, Haye B, Jacquemin C, Corrèze C
Unité de Recherche sur la Glande Thyroide et la Régulation Hormonale, U.96, INSERM, Hôpital du Kremlin-Bicêtre, France.
Mol Cell Endocrinol. 1991 Feb;75(2):123-31. doi: 10.1016/0303-7207(91)90226-i.
Changes in the sensitivity of adenylyl cyclase observed in pig thyroid cells cultured 2 days in the presence of thyroid-stimulating hormone (TSH) or forskolin were assessed by examining the properties of Gs protein. Chronic treatment of thyroid cells with various concentrations of TSH (0.01-1 mU/ml) or forskolin (0.1-10 microM) increased the response of adenylyl cyclase to a further stimulation by forskolin or NaF + AlCl3 ([AlF4]-). In contrast, the enzyme activation promoted by guanosine 5'-(beta,gamma-imido) triphosphate (Gpp(NH)p) was markedly affected. There was a significant increase in adenylyl cyclase activation by Gpp(NH)p in membranes from cells treated with low concentrations of TSH (less than or equal to 0.1 mU/ml) or forskolin (less than or equal to 1 microM) but a significant decrease in membranes from cells cultured with a higher concentration of TSH (1 mU/ml) or forskolin (10 microM). This decrease in Gpp(NH)p-stimulated adenylyl cyclase activity was mimicked by 8-bromo-cAMP but not by 1,9-dideoxyforskolin, a forskolin analogue which has lost its ability to activate adenylyl cyclase. There was a good correlation with the ability of Gs protein to be ADP-ribosylated by cholera toxin: labeling of Gs protein decreased following chronic treatment of thyroid cells with TSH (1 mU/ml) or forskolin (10 microM). In contrast, under the same experimental culture conditions a slight but significant increase in the quantity of Gs subunits was observed by immunoblotting analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
通过检测Gs蛋白的特性，评估了在促甲状腺激素（TSH）或福斯高林存在下培养2天的猪甲状腺细胞中腺苷酸环化酶敏感性的变化。用不同浓度的TSH（0.01 - 1 mU/ml）或福斯高林（0.1 - 10 microM）对甲状腺细胞进行长期处理，可增强腺苷酸环化酶对福斯高林或NaF + AlCl3（[AlF4]-）进一步刺激的反应。相反，鸟苷5'-（β，γ-亚氨基）三磷酸（Gpp(NH)p）促进的酶激活受到显著影响。低浓度TSH（小于或等于0.1 mU/ml）或福斯高林（小于或等于1 microM）处理的细胞的膜中，Gpp(NH)p激活腺苷酸环化酶的能力显著增加，但高浓度TSH（1 mU/ml）或福斯高林（10 microM）培养的细胞的膜中则显著降低。8-溴-cAMP可模拟Gpp(NH)p刺激的腺苷酸环化酶活性的这种降低，但1,9-二脱氧福斯高林（一种已失去激活腺苷酸环化酶能力的福斯高林类似物）则不能。这与Gs蛋白被霍乱毒素ADP-核糖基化的能力具有良好的相关性：用TSH（1 mU/ml）或福斯高林（10 microM）对甲状腺细胞进行长期处理后，Gs蛋白的标记减少。相反，在相同的实验培养条件下，通过免疫印迹分析观察到Gs亚基的数量有轻微但显著的增加。（摘要截短于250字）
