Regulation of aromatase gene expression in Leydig cells and germ cells
Regulation of aromatase gene expression in Leydig cells and germ cells
复制标题
DOI：
10.1016/s0960-0760(03)00343-1
复制
发表时间：
2003-09-01
影响因子：
4.1
通讯作者：
Carreau, S
中科院分区：
文献类型：
--
作者：
Bourguiba, S;Genissel, C;Carreau, S
睾丸将雄激素不可逆地转化为雌激素的能力与微粒体酶复合物芳香化酶的存在有关。虽然体细胞和生殖细胞（GC）具有产生雌激素的能力，但成年大鼠睾丸细胞，特别是新鲜纯化的Leydig细胞、粗线期精母细胞（PS）和圆形精子细胞（RS）中CYP 19基因表达的调控尚不完全清楚。在本研究中，我们分析了类固醇激素，转化生长因子β（TGF β），细胞因子（肿瘤坏死因子α，TNF α）和地塞米松（Dex）对这些纯化的成年大鼠睾丸细胞中CYP 19表达的影响。同时研究了曲细精管和支持细胞条件培养基对芳香化酶表达的生物学作用。采用高度特异性的定量竞争RT-PCR方法，我们证实睾酮（T）可增强间质细胞和生殖细胞中CYP 19基因的表达，并增加雌二醇的分泌。非芳香化雄激素5alpha-DHT对P450芳香化酶（P450 arom）基因表达的诱导作用与T相同，但对雌二醇输出的作用无效。在PS和RS中，观察到TGF β（1 ng/ml）单独或与T.相反，加入TNF α（20 ng/ml）增加PS中的P450 arom转录，尽管在RS中观察到抑制作用。TNF α与T一起降低PS和RS中P450 arom mRNA的量。在PS中，我们发现Dex正调控CYP 19表达，而在RS中负调控。此外，在PS中观察到Dex和TNF α对P450 arom mRNA表达的协同作用，而RS则记录了累加作用。因此，在生殖细胞中，TNF α可能通过PS中的启动子PIA（可能通过GAS元件上游的AP 1位点）增强芳香酶的表达，而在RS中，TNF α需要糖皮质激素作为共刺激因子来增加CYP 19基因表达。最后，在生精小管或支持细胞条件培养基的存在下，芳香化酶转录物的量在间质细胞和生殖细胞中增加，因此表明其他局部产生的调节剂，但未知，但来自支持细胞来源，与大鼠睾丸细胞中芳香化酶基因表达的调节有关。总之，使用成熟大鼠睾丸间质细胞，粗线期精母细胞和圆形精子细胞的体外模型，我们已经表明，有几个因素指导芳香化酶基因的表达，很明显，不仅启动子PII，但也启动子PI.4有关。(C)2003 Elsevier Ltd.保留所有权利。
The ability of the testis to convert irreversibly androgens into estrogens is related to the presence of a microsomal enzymatic complex named aromatase. Although somatic cells and germ cells (GC) have the capacity to produce estrogens the regulation of the CYP19 gene expression in adult rat testicular cells and specially in freshly purified Leydig cells, pachytene spermatocytes (PS) and round spermatids (RS) is not fully understood. In the present study we have analyzed the putative effects of steroid hormones, transforming growth factor beta (TGFbeta), cytokine (tumor necrosis factor alpha, TNFalpha) and dexamethasone (Dex) on CYP19 expression in these purified testicular cells from adult rat. In parallel the biological role of seminiferous tubules and Sertoli cells conditioned media on the expression of aromatase was studied. Using a highly specific quantitative competitive RT-PCR we established that testosterone (T) enhances CYP19 gene expression in Leydig cells and germ cells, and augments the estradiol outputs. The non-aromatizable androgen 5alpha-DHT induces the same effect as T on P450 aromatase (P450arom) gene expression but was inefficient on the estradiol output. In PS and RS an inhibitory effect on CYP19 gene transcription was observed with TGFbeta (1 ng/ml) alone or in combination with T. Conversely, the addition of TNFalpha (20 ng/ml) increases the P450arom transcription in PS although an inhibitory effect is observed in RS. Together with T, TNFalpha decreases the amount of P450arom mRNA in PS and RS. In PS we found that Dex regulates positively CYP19 expression and negatively in RS. Furthermore in PS a synergistic effect of Dex and TNFalpha on P450arom mRNA expression was observed whereas an additive one was recorded for RS. Therefore in germ cells TNFalpha likely enhances expression of aromatase through promoter PIA in PS, possibly via an AP1 site upstream the GAS element, while in RS TNFa requires glucocorticoids as a co-stimulator to increase CYP19 gene expression. Finally in presence of seminiferous tubules or Sertoli cell conditioned media, the amount of aromatase transcripts is increased in both Leydig cells and germ cells therefore suggesting that other locally produced modulators, yet unknown, but from Sertoli cell origin, are concerned in the regulation of the aromatase gene expression in rat testicular cells. In summary, using an in vitro model of mature rat Leydig cells, pachytene spermatocytes and round spermatids, we have shown that several factors direct the expression of the aromatase gene and it is obvious that not only promoter PII but also promoter PI.4 are concerned. (C) 2003 Elsevier Ltd. All rights reserved.