Carreau Serge, Delalande Christelle, Silandre Dorothée, Bourguiba Sonia, Lambard Sophie
Biochemistry-IBFA, EA 2608-USC INRA, Esplanade de la Paix, 14032 Caen Cedex, France.
Mol Cell Endocrinol. 2006 Feb 26;246(1-2):65-8. doi: 10.1016/j.mce.2005.11.021. Epub 2006 Jan 6.
Aromatase is a terminal enzyme which transforms irreversibly androgens into estrogens and it is present in the endoplasmic reticulum of numerous tissues. We have demonstrated that mature rat germ cells express a functional aromatase with a production of estrogens equivalent to that of Leydig cells. In humans in addition to Leydig cells, we have shown the presence of aromatase in ejaculated spermatozoa and in immature germ cells. In most tissues, high affinity estrogen receptors, ERalpha and/or ERbeta, mediate the role of estrogens. Indeed, in human spermatozoa, we have successfully amplified ERbeta mRNA but the protein was not detectable. Using ERalpha antibody we have detected two proteins in human immature germ cells: one at the expected size 66 kDa and another at 46 kDa likely corresponding to the ERalpha isoform lacking exon 1. In spermatozoa only the 46 kDa isoform was present, and we suggest that it may be located on the membrane. In addition, in men genetically deficient in aromatase, it is reported that alterations of spermatogenesis occur both in terms of the number and motility of spermatozoa. All together, these observations suggest that endogenous estrogens are important in male reproduction.
芳香化酶是一种将雄激素不可逆地转化为雌激素的终末酶，存在于众多组织的内质网中。我们已经证明，成熟的大鼠生殖细胞表达一种功能性芳香化酶，其雌激素生成量与睾丸间质细胞相当。在人类中，除了睾丸间质细胞外，我们还在射出的精子和未成熟生殖细胞中发现了芳香化酶的存在。在大多数组织中，高亲和力雌激素受体ERα和/或ERβ介导雌激素的作用。事实上，在人类精子中，我们成功扩增出了ERβ mRNA，但未检测到该蛋白。使用ERα抗体，我们在人类未成熟生殖细胞中检测到了两种蛋白：一种大小为预期的66 kDa，另一种为46 kDa，可能对应于缺少外显子1的ERα异构体。在精子中仅存在46 kDa的异构体，我们认为它可能位于细胞膜上。此外，据报道，在芳香化酶基因缺陷的男性中，精子发生在数量和活力方面均出现改变。综上所述，这些观察结果表明内源性雌激素在男性生殖中很重要。
