INTERNALIZATION; INTRACELLULAR BINDING OF GONADOTROPIN

牛的细胞核、溶酶体、粗面内质网和高尔基体以及质膜 黄体含有125I-人绒毛膜的特异性结合部位 促性腺激素(125I-hCG)。内化的125I-hCG与 上述所有细胞内细胞器中的受体都是完整的。 125I-hCG降解不是125I-hCG的主要后果 在孵化的前2小时内内化。这些发现可能 至少部分代表促性腺激素的细胞内途径 受体的合成和再循环。然而，这条路径既不是 明确记录了促性腺激素受体，数据也不是 存在表明细胞内结合部位没有功能性 意义。内化促性腺激素的功能意义 结合到细胞内细胞器的建议如下：a) 内化~(125)I-hCG与胞内细胞器结合的多样性 B)与某些细胞内细胞器(即高尔基体)的结合度很高 C)核联合和d)缺乏高水平的激素 在孵化的前2小时内降解。 为了评价其功能意义，我们将研究直接hCG。 对核RNA合成、RNA聚合酶活性、染色质的影响 密度和溶解度变化、mRNA退出、核苷三磷酸酶 活性、磷酸化和去磷酸化、125I-hCG结合和 黄体胞质内化及其对hCG和HCG的反应性 环状AMP。人绒毛膜促性腺激素对溶酶体、粗面内质网和高尔基体的直接作用 将研究酶的活性、磷酸化和去磷酸化。 以及侧壁(脑池或细胞质)的测定 受体和分离的溶酶体降解激素和/或的能力 感受器。将运行相应的细胞器控制(不添加激素) 同时。质膜也将包括在一些 用于比较的实验。所看到的任何影响都将扩展到包括 激素和组织特异性以及模拟环磷酸腺苷的可能性 HCG。将寻求在体外观察到的效应的体内确认 使用超数排卵的大鼠。荷尔蒙的浓度是否在 所看到的影响将对应于生理水平和明显的 激素结合的离解常数将被紧密压缩。 所获得的结果可能会在以下方面开辟新的令人兴奋的可能性 以前从未被认为存在的促性腺激素作用。

Nuclei, lysosomes, rough ER and Golgi as well as plasma membranes of bovine corpora lutea contain specific binding sites for 125I-human chorionic gonadotropin (125I-hCG). The internalized 125I-hCG associated with the receptors in all of the above intracellular organelles in an intact form. 125I-hCG degradation is not a primary consequence of 125I-hCG internalization during the first 2 hrs of incubation. These findings may represent, at least in part, the intracellular pathway of gonadotropin receptor synthesis and recycling. However, this pathway is neither documented unequivocally for gonadotropin receptors, nor does the data exist to show that the intracellular binding sites have no functional significance. Functional significance for internalized gonadotropin binding to the intracellular organelles is suggested by the following, a) diversity of intracellular organelles to which internalized 125I-hCG binds b) very high binding to some of the intracellular organelles (i.e., Golgi) c) nuclear association and d) the lack of high levels of hormone degradation during the first 2 hrs of incubation. To evaluate the functional significance, we will study the direct hCG effects on nuclear RNA synthesis, activity of RNA polymerases, chromatin density and solubility changes, exit of mRNA, nucleoside triphosphatase activity, phosphorylation and dephosphorylation, 125I-hCG binding and internalization in luteal cytoplasts and their responsiveness to hCG and cyclic AMP. The direct hCG effects on lysosomal, RER and Golgi intrinsic enzyme activities, phosphorylation and dephosphorylation will be studied along with determination of sidedness (cisternal or cytoplasmic) of receptors and capability of isolated lysosomes to degrade hormone and/or receptors. Corresponding organelle controls (no hormone added) will be run simultaneously. Plasma membranes will also be included in some of the experiments for comparison. Any effects seen will be extended to include hormonal and tissue specificity and possibility of cyclic AMP mimicking hCG. In vivo confirmation of observed effects in vitro will be sought using superovulated rats. Whether the concentration of hormone at which the effects are seen will correspond to physiological levels and apparent dissociation constant for hormone binding will be closely scruntinized. The results obtained may open up new and exciting possibilities in gonadotropin action which were never thought to exist before.