Insulin-Like Growth Factor 3 Regulates Expression of Genes Encoding Steroidogenic Enzymes and Key Transcription Factors in the Nile Tilapia Gonad
Insulin-Like Growth Factor 3 Regulates Expression of Genes Encoding Steroidogenic Enzymes and Key Transcription Factors in the Nile Tilapia Gonad
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胰岛素样生长因子 3 调节尼罗罗非鱼性腺中类固醇生成酶和关键转录因子编码基因的表达
DOI：
10.1095/biolreprod.111.096248
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发表时间：
2012-05-01
影响因子：
3.6
通讯作者：
Wang, Deshou
中科院分区：
文献类型：
--
作者：
Li, Minghui;Wu, Fengrui;Wang, Deshou
胰岛素样生长因子（IGFs）在硬骨鱼性腺发育和生殖过程中具有广泛的生理作用。在本研究中，igf 3 mRNA在罗非鱼卵巢中的表达量在孵化后5 - 40天高于精巢，但在孵化后50 - 70天低于精巢。一致的是，Igf 3蛋白信号检测XX和XY性腺的体细胞从10日龄至成年的免疫组化，使用特异性Igf 3多克隆抗体。在原代培养的卵巢和睾丸细胞与重组Igf 3孵育显着增加nr 5a 1，foxl 2，dmrt 1，cyp 19 a1 a，cyp 11 a1，cyp 11b 2，hsd 3b 2，cyp 17 a1表达的时间和剂量依赖性的方式。在HEK 293细胞中使用荧光素酶测定的启动子分析显示igf 3启动子活性被Nr 5a 1（Sf 1）直接激活，并被Foxl 2、Nr 0 b1 a（Dax 1）和Nr 0 b1 b（Dax 2）进一步增强，但被Dmrt 1和雌激素受体（Esr 1、Esr 2a或Esr 2b）沿着17 β-雌二醇处理抑制。此外，igf 3启动子活性略有增加，单独毛喉素治疗，但协同上调与nr 5a 1转染。这些体外实验结果与igf 3在性腺分化早期的表达谱相关。我们的研究结果表明igf 3参与鱼类性腺类固醇合成，因为它能够调节foxl 2，dmrt 1，nr 5a 1和类固醇合成酶的表达。igf 3的表达反过来又受转录因子Foxl 2、Dmrt 1和Nr 5a 1以及17 β-雌二醇处理的调节。
Insulin-like growth factors (Igfs) are implicated in a wide variety of physiological roles in teleost gonadal development and reproduction. In the present study, igf3 mRNA expression in the tilapia ovary was found to be higher than in the testis from 5 to 40 days after hatching (dah) but was lower than that in testis from 50 to 70 dah. Consistently, Igf3 protein signal was detected in the somatic cells of XX and XY gonads from 10 dah until adulthood by immunohistochemistry, using a specific Igf3 polyclonal antibody. Incubation of ovarian and testicular cells in primary culture with recombinant Igf3 significantly increased nr5a1, foxl2, dmrt1, cyp19a1a, cyp11a1, cyp11b2, hsd3b2, and cyp17a1 expression in a time- and dose-dependent manner. Promoter analysis using luciferase assays in HEK293 cells revealed that igf3 promoter activity was directly activated by Nr5a1 (Sf1) and further enhanced by Foxl2, Nr0b1a (Dax1), and Nr0b1b (Dax2) but repressed by Dmrt1 and estrogen receptor (Esr1, Esr2a, or Esr2b) along with 17beta-estradiol treatment. In addition, igf3 promoter activity was increased slightly by forskolin treatment alone but synergistically up-regulated by transfection with nr5a1. These in vitro results correlated well with the expression profile of igf3 during early gonad differentiation. Our results indicated that igf3 is involved in fish gonad steroidogenesis because of its ability to regulate the expression of foxl2, dmrt1, and nr5a1 and steroidogenic enzymes. The expression of igf3 is in turn regulated by transcription factors Foxl2, Dmrt1, and Nr5a1, as well as by 17beta-estradiol treatment.