Staub Christophe, Rauch Michel, Ferrière François, Trépos Mélanie, Dorval-Coiffec Isabelle, Saunders Philippa T, Cobellis Gilda, Flouriot Gilles, Saligaut Christian, Jégou Bernard
INSERM, U625, GERHM, IFR 140, Campus de Beaulieu, Univ Rennes I, Bretagne, France.
Biol Reprod. 2005 Oct;73(4):703-12. doi: 10.1095/biolreprod.105.042796. Epub 2005 Jun 8.
Testicular descent corresponds to migration of the testis from the abdominal cavity to the scrotum and is essential for proper functioning of the testis. Recent advances in the characterization of estrogen receptor (ESR) subtypes and isoforms in various tissues prompted us to study ESRs within the gubernaculum testis, a structure involved in testicular descent. In the rat gubernaculum, we searched for ESR alpha (Esr1) and beta (Esr2) and for the androgen receptor (Ar), androgens being known to regulate testicular descent. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that Esr1, Esr2, and Ar mRNAs were all expressed in the gubernaculum. Using PEETA (Primer extension, Electrophoresis, Elution, Tailing, and Amplification), we established that all Esr1 leader exons, previously identified in other organs, such as the uterus and pituitary, were transcribed in the gubernaculum, with the major form being O/B. The RNA protection assays, RT-PCR, and Western blot experiments revealed that isoform-specific mRNA transcripts generated by alternative splicing of the C-leader sequence on coding exons 1 and 2 of the Esr1 gene gave the 46- and 66-kDa ESR1 proteins. The ESR1 and AR proteins were found to colocalize in the parenchymal cells of the gubernaculum early in development, whereas AR also was strongly expressed in the muscular cells, both during fetal and postnatal life. The ESR2 protein was weakly expressed, principally in the muscular cells, but only once testicular descent had occurred. The levels of the 46-kDa ESR1 variant (ER46) exceeded those of the 66-kDa ESR1 form (ER66) at periods when the gubernaculum developed. Conversely, the 66-kDa form appears to predominate clearly when the gubernaculum growth was low or completed. The possible role of estrogens on the modulation of the androgen-dependent growth of the gubernaculum and, more widely, on testicular descent is discussed.
睾丸下降是指睾丸从腹腔迁移至阴囊，对于睾丸的正常功能至关重要。近期，在各种组织中对雌激素受体（ESR）亚型和异构体的特性研究取得了进展，这促使我们研究睾丸引带中的ESR，睾丸引带是参与睾丸下降的一个结构。在大鼠睾丸引带中，我们查找了ESRα（Esr1）和β（Esr2）以及雄激素受体（Ar），已知雄激素可调节睾丸下降。逆转录聚合酶链反应（RT-PCR）显示，Esr1、Esr2和Ar mRNA均在睾丸引带中表达。使用PEETA（引物延伸、电泳、洗脱、加尾和扩增），我们确定先前在子宫和垂体等其他器官中鉴定出的所有Esr1前导外显子在睾丸引带中均被转录，主要形式为O/B。RNA保护分析、RT-PCR和蛋白质印迹实验表明，Esr1基因编码外显子1和2上C-前导序列的可变剪接产生的异构体特异性mRNA转录本产生了46 kDa和66 kDa的ESR1蛋白。在发育早期，ESR1和AR蛋白在睾丸引带的实质细胞中共定位，而AR在胎儿期和出生后均在肌肉细胞中强烈表达。ESR2蛋白表达较弱，主要在肌肉细胞中表达，但仅在睾丸下降发生后才出现。在睾丸引带发育期间，46 kDa的ESR1变体（ER46）水平超过66 kDa的ESR1形式（ER66）。相反，当睾丸引带生长缓慢或完成时，66 kDa的形式似乎明显占主导。本文讨论了雌激素在调节雄激素依赖性睾丸引带生长以及更广泛地在睾丸下降方面可能发挥的作用。
