Erämaa M, Heikinheimo K, Voutilainen R
Department of Pathology, University of Helsinki, Finland.
J Clin Endocrinol Metab. 1992 Sep;75(3):806-11. doi: 10.1210/jcem.75.3.1325475.
Inhibin subunit messenger ribonucleic acids (mRNAs) are expressed during the gonadal development of rodent, ovine, and bovine fetuses. We investigated the expression of inhibin subunit mRNAs in human fetal gonads between 13 and 25 weeks of gestational age. In testes, the alpha-subunit mRNA was highly expressed at the beginning of the second trimester and its expression level slightly decreased thereafter. Also the beta B-subunit mRNA was detected throughout this time period but no significant developmental change could be observed. Northern analysis showed a 1.6-kilobase (kb) transcript for alpha-chain, as well as two bands of about 5.0 and 4.5 kb for the beta B-subunit. A human Leydig cell tumor also expressed the 1.6-kb alpha-subunit. By filter hybridization studies, the beta A-chain mRNA could not be observed in testes and none of the three inhibin subunits were detectable in the ovaries at this developmental stage. However, reverse-transcription polymerase chain reaction analysis revealed the expression of all three inhibin subunit mRNAs in testes. As studied by in situ hybridization, inhibin alpha-subunit hybridization signal was most intense in seminiferous tubules and weaker hybridization was observed in interstitial cells of the fetal testis. In primary cultures of fetal testicular cells, dibutyryl cAMP (0.2 mmol/L) stimulated alpha- and beta B-mRNAs. It augmented alpha- and beta B-mRNA accumulation up to 6- and 2.5-fold, respectively. Thus, we conclude that: 1) during the second trimester of gestation, human fetal testes express all three inhibin subunit mRNAs, although the beta A-chain expression appears to be low; 2) during this developmental stage inhibin subunit mRNAs are not detectable in ovaries; 3) in human fetal testes, the alpha-chain mRNA is localized to both intratubular and interstitial cells; 4) in cultured human testicular cells, inhibin alpha- and beta B-subunit mRNAs are regulated by a cAMP-dependent pathway.
抑制素亚基信使核糖核酸（mRNA）在啮齿动物、绵羊和牛胎儿的性腺发育过程中表达。我们研究了孕13至25周人类胎儿性腺中抑制素亚基mRNA的表达。在睾丸中，α亚基mRNA在妊娠中期开始时高表达，此后其表达水平略有下降。在此期间也检测到了βB亚基mRNA，但未观察到明显的发育变化。Northern分析显示α链有一条1.6千碱基（kb）的转录本，βB亚基有两条约5.0和4.5 kb的条带。人睾丸间质细胞瘤也表达1.6 kb的α亚基。通过滤膜杂交研究，在睾丸中未观察到βA链mRNA，在这个发育阶段的卵巢中也未检测到三种抑制素亚基中的任何一种。然而，逆转录聚合酶链反应分析显示睾丸中所有三种抑制素亚基mRNA均有表达。通过原位杂交研究，抑制素α亚基杂交信号在生精小管中最强，在胎儿睾丸的间质细胞中观察到较弱的杂交信号。在胎儿睾丸细胞的原代培养中，二丁酰环磷腺苷（0.2 mmol/L）刺激α和βB mRNA。它分别使α和βB mRNA的积累增加了6倍和2.5倍。因此，我们得出以下结论：1）在妊娠中期，人类胎儿睾丸表达所有三种抑制素亚基mRNA，尽管βA链表达似乎较低；2）在这个发育阶段，卵巢中未检测到抑制素亚基mRNA；3）在人类胎儿睾丸中，α链mRNA定位于小管内和间质细胞；4）在培养的人类睾丸细胞中，抑制素α和βB亚基mRNA受环磷腺苷依赖性途径调控。
