Follicle growth and granulosa cell health are dependent on the secretion of estradiol from granulosa cells. Estradiol is synthesized from androgen precursor by cytochrome P450 aromatase (CYP19A1), and in cattle CYP19A1 messenger RNA has a short half-life but a long (3.5 kb) 3'-untranslated region (3'UTR), suggesting that posttranscriptional regulation may be important for control of enzyme activity. We tested this hypothesis by inserting the CYP19A1 3'UTR and fragments thereof into a reporter vector between the end of the luciferase coding region and the polyadenylation signal. The full-length aromatase 3'UTR suppressed luciferase activity to 10% of control levels, and smaller fragments showed that this inhibitory activity lies between +926 and +1134 of the 3'UTR. Protein-RNA cross-linking experiments revealed that these 3'UTR fragments formed an RNA-protein complex of approximately 70 kDa that was present in granulosa cells but not in corpus luteum, lung, liver, kidney, pancreas, or bladder extracts. The RNA-binding activity was specific to the 3'UTR, as shown by competition experiments with unlabeled RNA, and was present only in 3'UTR constructs that inhibited luciferase activity. These data suggest that posttranscriptional regulation is an important component of the control of CYP19A1 expression and involves protein binding to a specific sequence in the 3'UTR.

中文翻译：

---

推定的蛋白质-RNA复合物调节牛颗粒细胞中细胞色素P450芳香化酶（CYP19A1）的转录后加工。

卵泡的生长和颗粒细胞的健康取决于颗粒细胞中雌二醇的分泌。雌二醇是通过细胞色素P450芳香化酶（CYP19A1）从雄激素前体合成的，牛中CYP19A1信使RNA的半衰期短，但3'-非翻译区（3'UTR）长（3.5 kb），提示转录后调控可能是对于控制酶活性很重要。我们通过将CYP19A1 3'UTR及其片段插入荧光素酶编码区末端与聚腺苷酸化信号之间的报告载体中，测试了这一假设。全长芳香化酶3'UTR将萤光素酶活性抑制到对照水平的10％，较小的片段表明该抑制活性位于3'UTR的+926和+1134之间。蛋白质-RNA交联实验表明，这些3' UTR片段形成大约70 kDa的RNA-蛋白质复合物，存在于颗粒细胞中，但不存在于黄体，肺，肝，肾，胰腺或膀胱提取物中。如未标记RNA的竞争实验所示，RNA结合活性对3'UTR具有特异性，并且仅在抑制萤光素酶活性的3'UTR构建物中存在。这些数据表明，转录后调节是CYP19A1表达控制的重要组成部分，涉及蛋白质与3'UTR中特定序列的结合。并且仅存在于抑制荧光素酶活性的3'UTR构建物中。这些数据表明，转录后调节是CYP19A1表达控制的重要组成部分，涉及蛋白质与3'UTR中特定序列的结合。并且仅存在于抑制荧光素酶活性的3'UTR构建物中。这些数据表明，转录后调节是CYP19A1表达控制的重要组成部分，涉及蛋白质与3'UTR中特定序列的结合。