STUDIES ON BINDING OF RADIOLABELED THYROTROPIN TO CULTURED HUMAN THYROID-CELLS
STUDIES ON BINDING OF RADIOLABELED THYROTROPIN TO CULTURED HUMAN THYROID-CELLS
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DOI：
10.1210/endo-103-6-2011
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发表时间：
1978-01-01
期刊：
影响因子：
4.8
通讯作者：
RAPOPORT, B
中科院分区：
文献类型：
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作者：
YAMAMOTO, M;RAPOPORT, B
在一项研究中使用了培养的人类甲状腺腺瘤细胞系，旨在比较 TSH [促甲状腺素] 对细胞 c[环]AMP 生成的刺激作用与放射性标记的 TSH 与细胞的结合。 37度。 C，[125I]TSH 与甲状腺细胞悬液的特异性结合在 20 分钟时达到最大，并且通过添加过量的 TSH 来逆转。与响应 TSH 刺激而产生的细胞 cAMP 在 pH 7.5 时达到最大不同，[125I]TSH 与细胞的结合在 pH 5.5 时达到最大，并逐渐下降直至 pH 8.5。增加 NaCl 浓度会逐渐抑制 TSH 的细胞结合；在生理盐浓度下，几乎检测不到 TSH 结合。 [125I]TSH与细胞结合的竞争性抑制研究揭示了解离常数为5.5倍的结合位点。 pH 7.4 时 10-8 M GH [生长激素]、PRL [催乳素]、hCG [人绒毛膜促性腺激素]、FSH [促卵泡激素]、胰岛素和胰高血糖素不与 [125I]TSH 结合竞争。 ACTH 是 [125I]TSH 结合的有效抑制剂。尽管 ACTH 对 TSH 结合具有抑制作用，但 ACTH 对细胞 cAMP 生成影响很小或没有影响。高浓度的 ACTH 不会抑制 TSH 对 cAMP 生成的生物学作用。 [125I]TSH 与空塑料培养皿的特异性结合具有时间依赖性、可逆性，并表现出与甲状腺细胞结合相同的激素特异性。 pH 值和 NaCl 浓度对 TSH 与培养皿结合的影响与对细胞结合的影响相似，但不相同。这项研究对 [125I]TSH 与培养的人类甲状腺细胞结合的生物学意义提出了严重的问题。
A line of cultured human thyroid adenoma cells was used in a study designed to compare the stimulatory effect of TSH [thyrotropin] on cellular c[cyclic]AMP generation with the binding of radiolabeled TSH to the cells. At 37.degree. C, specific binding of [125I]TSH to suspensions of thyroid cells was maximal at 20 min and was reversed by the addition of excess TSH. Unlike the generation of cellular cAMP in response to TSH stimulation, which was maximal at pH 7.5, the binding of [125I]TSH to the cells was maximal at pH 5.5 and progressively declined up to pH 8.5. Increasing NaCl concentrations progressively inhibited cellular binding of TSH; at physiological salt concentrations, almost no TSH binding was detectable. Competitive inhibition studies of [125I]TSH binding to cells revealed a binding site with a dissociation constant of 5.5 .times. 10-8 M at pH 7.4 GH [growth hormone], PRL [prolactin], hCG [human chorionic gonadotropin], FSH [follitropin], insulin, and glucagon did not compete with [125I]TSH binding. ACTH was a potent inhibitor of [125I]TSH binding. Despite this inhibitory effect on TSH binding, ACTH had little or no effect on cellular cAMP generation. High concentrations of ACTH did not inhibit the biological effect of TSH on cAMP generation. Specific binding of [125I]TSH to empty plastic culture dishes was time dependent, reversible and displayed a hormonal specificity identical to binding to thyroid cells. The effects of pH and NaCl concentrations on TSH binding to dishes were similar but not identical to those on cellular binding. This study raises serious questions as to the biological significance of [125I]TSH binding to cultured human thyroid cells.