Child & Family Research Institute and Department of Obstetrics & Gynecology, University of British Columbia, Vancouver, British Columbia, Canada.
Biol Reprod. 2011 Sep;85(3):431-41. doi: 10.1095/biolreprod.111.092593. Epub 2011 May 25.
Sex hormone-binding globulin (SHBG) transports androgens and estrogens in blood and regulates their access to target tissues. Hepatic production of SHBG fluctuates throughout the life cycle and is influenced primarily by metabolic and hormonal factors. Genetic differences also contribute to interindividual variations in plasma SHBG levels. In addition to controlling the plasma distribution, metabolic clearance, and bioavailability of sex steroids, SHBG accumulates in the extravascular compartments of some tissues and in the cytoplasm of specific epithelial cells, where it exerts novel effects on androgen and estrogen action. In mammals, the gene-encoding SHBG is expressed primarily in the liver but also at low levels in other tissues, including the testis. In subprimate species, Shbg expression in Sertoli cells is under the control of follicle-stimulating hormone and produces the androgen-binding protein that influences androgen actions in the seminiferous tubules and epididymis. In humans, the SHBG gene is not expressed in Sertoli cells, but its expression in germ cells produces an SHBG isoform that accumulates in the acrosome. In fish, Shbg is produced by the liver but has a unique function in the gill as a portal for natural steroids and xenobiotics, including synthetic steroids. However, salmon have retained a second, poorly conserved Shbg gene that is expressed only in ovary, muscle, and gill and that likely exerts specialized functions in these tissues. The present review compares the production and functions of SHBG in different species and its diverse effects on reproduction.
性激素结合球蛋白 (SHBG) 在血液中转运雄激素和雌激素，并调节其进入靶组织的途径。SHBG 的肝内产生在整个生命周期中波动，主要受代谢和激素因素的影响。遗传差异也导致血浆 SHBG 水平的个体间差异。除了控制性激素在血浆中的分布、代谢清除率和生物利用度外，SHBG 还在一些组织的血管外腔室和特定上皮细胞的细胞质中积累，从而对雄激素和雌激素作用产生新的影响。在哺乳动物中，编码 SHBG 的基因主要在肝脏中表达，但在其他组织中也低水平表达，包括睾丸。在次灵长类动物中，Sertoli 细胞中的 Shbg 表达受卵泡刺激素的控制，产生雄激素结合蛋白，影响生精小管和附睾中的雄激素作用。在人类中，SHBG 基因在 Sertoli 细胞中不表达，但它在生殖细胞中的表达产生了一种 SHBG 同工型，在顶体中积累。在鱼类中，SHBG 由肝脏产生，但在鳃中具有独特的功能，作为天然类固醇和外源性化学物质（包括合成类固醇）的门户。然而，鲑鱼保留了第二个，功能较差的 Shbg 基因，仅在卵巢、肌肉和鳃中表达，可能在这些组织中发挥特殊功能。本综述比较了不同物种中 SHBG 的产生和功能及其对生殖的多样化影响。
