Santiemma V, Rosati P, Guerzoni C, Mariani S, Beligotti F, Magnanti M, Garufi G, Galoni T, Fabbrini A
Istituto di Clinica Medica V, La Sapienza University of Rome, Italy.
J Steroid Biochem Mol Biol. 1992 Oct;43(5):423-9. doi: 10.1016/0960-0760(92)90080-3.
Sertoli cells play a pivotal role in the regulation of spermatogenesis as they provide the anatomical basis of the blood-testis barrier. In the present paper we report some results of our studies on the ultrastructural features, the responsiveness to FSH, and the ability to secrete androgen-binding protein (ABP) of human Sertoli cells in vitro. The nucleus showed the characteristic foldings of the nuclear membrane, scattered chromatin, and a fibrillar nucleolus. In the cytoplasm Charcot-Boettcher crystals were present and active phagocytic activity was documented by the presence of vacuoles containing lipids and cellular debris. Human Sertoli cells in culture responded to FSH with a maximal rise in cAMP that was approx. 3-fold. This response to FSH is comparable to that reported for the adult rat but lower than that of the immature rat, and suggests that human as well as rat Sertoli cells could have a reduced response to FSH since sexual maturation was achieved. As no evidence has been reported on ABP secretion by human Sertoli cells in culture we evaluated the concentration of this protein in the Sertoli cell spent media. Human Sertoli cells in culture produced ABP and the response to FSH was dose-related. The Kd value of human ABP (hABP) was approx. 7.5 nM, being slightly higher than that of the rat ABP and an order of magnitude different from that of sex hormone-binding globulin (SHBG) present in human plasma. We also measured the association and dissociation rates of dihydrotestosterone-hABP complexes and the Kd/Ka ratio was very close to the value of Kd of the Scatchard analysis. The differences between hABP and SHBG may open the way to the selective measurement of ABP in many conditions of male infertility.
支持细胞在精子发生的调节中起关键作用，因为它们为血睾屏障提供了解剖学基础。在本文中，我们报告了我们对体外培养的人支持细胞的超微结构特征、对促卵泡激素（FSH）的反应性以及分泌雄激素结合蛋白（ABP）能力的一些研究结果。细胞核显示出核膜的特征性折叠、散在的染色质和一个纤维状核仁。在细胞质中存在夏科-博伊特勒晶体，含有脂质和细胞碎片的液泡的存在证明了活跃的吞噬活性。培养的人支持细胞对FSH的反应是细胞内环磷酸腺苷（cAMP）最大程度升高，约为3倍。这种对FSH的反应与成年大鼠的报道相当，但低于未成熟大鼠，这表明由于已达到性成熟，人和大鼠的支持细胞对FSH的反应可能都有所降低。由于尚未有关于培养的人支持细胞分泌ABP的报道，我们评估了支持细胞培养液中该蛋白的浓度。培养的人支持细胞产生ABP，并且对FSH的反应呈剂量依赖性。人ABP（hABP）的解离常数（Kd）值约为7.5 nM，略高于大鼠ABP，与存在于人体血浆中的性激素结合球蛋白（SHBG）相差一个数量级。我们还测量了二氢睾酮-hABP复合物的结合和解离速率，Kd/Ka比值非常接近斯卡查德分析的Kd值。hABP和SHBG之间的差异可能为在许多男性不育情况下选择性测量ABP开辟道路。
