TESTOSTERONE AT HIGH-CONCENTRATIONS INTERACTS WITH THE HUMAN ANDROGEN RECEPTOR SIMILARLY TO DIHYDROTESTOSTERONE
TESTOSTERONE AT HIGH-CONCENTRATIONS INTERACTS WITH THE HUMAN ANDROGEN RECEPTOR SIMILARLY TO DIHYDROTESTOSTERONE
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DOI：
10.1210/endo-126-2-1165
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发表时间：
1990-02-01
期刊：
影响因子：
4.8
通讯作者：
WILSON, JD
中科院分区：
文献类型：
--
作者：
GRINO, PB;GRIFFIN, JE;WILSON, JD
睾酮和二氢睾酮被认为是通过与雄激素靶组织中的单个细胞内受体蛋白相互作用来发挥其雄激素作用。然而，在胎儿时期，睾酮介导沃尔夫管进入附睾、输精管和精囊的男性化，而泌尿生殖窦和外生殖器需要睾酮原位转化为二氢睾酮才能进行男性发育。为什么睾酮提供的信号需要在某些雄激素靶组织中被放大，而在其他组织中则不然，这仍然是一个谜。为了深入了解这些雄激素的不同作用，我们研究了它们与从 5α-还原酶缺乏症患者的生殖器皮肤培养的成纤维细胞中的人类雄激素受体的相互作用。在这些细胞中形成的二氢睾酮的量可以忽略不计，并且在一些实验中，残余的5α-还原酶活性被5α-还原酶抑制剂非那雄胺进一步阻断。成纤维细胞单层的饱和度分析揭示了与睾酮和二氢睾酮的结合量相似，并且二氢睾酮的结合亲和力平均比睾酮大约2倍。 [3H]睾酮与受体的解离速率也比[3H]二氢睾酮快5倍。在热稳定性实验中，[3H]睾酮-受体复合物在42℃下用2nM[3H]睾酮表现出明显的不稳定性，而用20nM[3H]睾酮时，受体稳定性与用[3h]二氢睾酮观察到的相似。在上调实验中，24小时后，2 nM [3H]睾酮使特异性雄激素受体结合增加34%，而20 nM [3H]睾酮平均增加64%。我们的结果表明，与二氢睾酮残基相比，睾酮的雄激素效力较弱，因为其与雄激素受体的相互作用较弱，最明显地表现为睾酮与受体解离速率的增加。然而，当以相对较高的浓度存在时，睾酮通过质量作用克服了这一缺陷。以这种方式，高浓度的睾酮作为旁分泌因子而不是循环激素可能能够使沃尔夫管男性化，而男性分化和男性泌尿生殖道远端部分的生长可能需要代谢放大步骤，即睾酮原位转化为二氢睾酮。
Testosterone and dihydrotestosterone are believed to exert their androgenic effects by interacting with a single intracellular receptor protein in androgen target tissues. During fetal life, however, testosterone mediates the virilization of the Wolffian ducts into the epididymis, vas deferens, and seminal vesicles, whereas the urogenital sinus and external genitalia require the in situ conversion of testosterone to dihydrotestosterone to undergo male development. The reason whey the signal provided by testosterone needs to be amplified in some androgen target tissues but not in others remains an enigma. To provide insight into the different actions of these androgens we studied their interaction with the human androgen receptor in fibroblasts cultured from the genital skin of a patient with 5.alpha.-reductase deficiency. Dihydrotestosterone was formed in negligible amounts in these cells, and in some experiments the residual 5.alpha.-reductase activity was further blocked with the 5.alpha.-reductase inhibitor finasteride. Saturation analysis in fibroblast monolayers disclosed similar amounts of binding with testosterone and dihydrotestosterone, and the affinity of binding of dihydrotestosterone was, on the average, about 2-fold greater than that of testosterone. [3H]Testosterone also exhibited a 5-fold faster dissociation rate from the receptor than [3H]dihydrotestosterone. In thermolability experiments the [3H]testosterone-receptor complex displayed marked instability at 42 C with 2 nM [3H]testosterone, whereas with 20 nM [3H]testosterone, receptor stability was similar to that seen with [3h]dihydrotesterone. In up-regulation experiments, 2 nM [3H]testosterone produced a 34% increase in specific androgen receptor binding after 24 h, whereas 20 nM [3H]testosterone produced an average increase of 64%. Our results suggest that the weaker androgenic potency of testosterone compared to that of dihydrotesterone residues in its weaker interaction with the androgen receptor, most clearly demonstrable as an increase in the dissociation rate of testosterone from the receptor. When present in relatively high concentrations, however, tetosterone overcomes this defect by mass action. In this manner, testosterone in high concentrations and acting as a paracrine factor rather than a circulating hormone may be able to virilize the Wolffian ducts, whereas male differentiation and growth of the distant portions of the male urogenital tract may require a metabolic amplification step, namely the in situ conversion of testosterone to dihydrotestosterone.