Expression and activity of 17β-hydoxysteroid dehydrogenase type 3 in the human apocrine sweat gland

人类大汗腺是一种独特的雄激素靶组织，在男性和女性的青春期发育。尽管女性的血清睾酮和双氢睾酮水平比男性低得多，但这些活性雄激素的核内浓度在两性之间没有差异。17β-羟基类固醇脱氢酶（17β-HSD） 3型在睾丸和腹部脂肪组织中表达，在将雄烯二酮转化为睾酮方面具有强大的活性。在本研究中，我们研究了3型同工酶是否存在于人类大汗腺中。腋臭患者腋窝皮肤新鲜分离的大汗腺，-70℃保存，大汗腺匀浆与200 nM的^ 3h -雄烯二酮和1 mM的NADPH孵育20分钟。在中性pH或碱性条件下，加入15型5α-还原酶抑制剂mk386，以防止酶对底物的快速消耗。获得了更多的结果。(1)辅助因子的作用：NADPH存在时，酶的反应速度比NADPH生成系统或NADH更快。(2) pH的影响：在pH为5.5和pH为9.0时，酶活性出现了两个高峰。(3)酶活性的亚细胞定位：在pH 5.0和9.0时，胞浆部分的酶活性最高，但低于匀浆的酶活性。其他部分如粗核、线粒体和微粒体部分表现出较小的活性。结果与定位于微粒体部分的3型同工酶不同。然而，这与Hodgins等人先前的报告一致，他们也发现细胞质中存在主要活性。(4) RT-PCR检测3型同工酶mRNA的表达：在大汗腺的同工酶和大汗腺周围结缔组织衍生的成纤维细胞（离体大汗腺含有少量结缔组织）中，35个周期检测到3型表达。因此，尽管人类大汗腺表达17β- HSD 3型mRNA，并像3型同工酶一样在pH 5.0时积极地将雄烯二酮转化为睾酮，但亚细胞定位与该同工酶不同。我们实验中的亚细胞分离是否成功还需要进一步的研究。此外，必须研究一类新的同工酶存在的可能性。少

The human apocrine sweat gland is a unique androgen target tissue which develops in adolescence both in males and females. In spite of much lower serum levels of testosterone and dihydrotestosterone in females than males, the intranuclear concentrations of these active androgens do not differ between the two sexes. 17β-Hydroxysteroid dehydrogenase (17β-HSD) type 3 is express ed in the testes and abdominal adipose tissues and has potent activity in converting androstenedione to testosterone. In the present study, we studied whether the type 3 isozyme exhists in the human apocrine gland. Freshly isolated apocrine glands from axillary skin of patients with osmidrosis were stored at -70 C. Homogenates of apocrine glands were incubated with 200 nM of ^3H-androstenedione and 1 mM of NADPH for 20 min. At neutral pH or alkaline conditions, MK 386, a type 1 5α-reductase inhibitor, was included in the mixture in order to prevent rapid consumption of the substrate by the enzyme. The following res … More ults were obtained. (1) Effect of cofactors : the enzyme reaction was faster in the presence of NADPH than NADPH-generating system or NADH. (2) Effect of pH : two peaks of the enzyme activities were obtained at pH 5.5 an pH 9.0. (3) Subcellular localization of the enzyme activity : the highest activity was observed in the cytosol fraction at both pH 5.0 and 9.0, although it was lower than the activity of homogenates. Other fractions such as crude nuclear, mitochondrial and microsomal fractions exhibited lesser activities. The results differ from the localization of the type 3 isozyme which localizes in the microsomal fraction. However, they are consistent with the previous report by Hodgins et al. who also found the presence of the major activity in the cytosol. (4) mRNA expression of the type 3 isozyme by RT-PCR : type 3 expression was detected at 35 cycles in the homogemate of the apocrine gland and cultured fibroblasts derived from the connective tissue surrounding the gland (the isolated apocrine gland contained a small amount of connecive tissues). Thus, although human apocrine glands express mRNA of 17β- HSD type 3 and actively converts androstenedione to testosteron at pH 5.0 like the type 3 isozyme, subcellular localization is different from that of this isozyme. Further studies are required to check whether the subcellular fractionation in our experiment was successful. In addition, the possibility of the presence of a new class of the isozyme must be investigated. Less