Department of Physiology and Biophysics, University of Illinois at Chicago, United States.
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Illinois at Chicago College of Medicine, United States.
J Steroid Biochem Mol Biol. 2019 Jun;190:183-192. doi: 10.1016/j.jsbmb.2019.04.003. Epub 2019 Apr 4.
Luteinizing hormone and human chorionic gonadotropin (hCG) bind to the luteinizing hormone/chorionic gonadotropin receptor (LHCGR). LHCGR is required to maintain corpus luteum function but the mechanisms involved in the regulation of LHCGR in human luteal cells remain incompletely understood. This study aimed to characterize the expression of LHCGR mRNA in primary human luteinized granulosa cells (hLGCs) obtained from patients undergoing in vitro fertilization and to correlate LHCGR expression with the response of hLGCs to hCG by assessing the expression of genes known to be markers of hCG actions. The results show that LHCGR expression is low in freshly isolated cells but recovers rapidly in culture and that hCG maintains LHCGR expression, suggesting a positive feedback loop. The activity of a LHCGR-LUC reporter increased in cells treated with hCG but not with follicle-stimulating hormone. Treatment with hCG also stimulated the expression of genes involved in steroidogenesis in a time-dependent manner. LHCGR promoter expression was found to be regulated by SP1, which we show is highly expressed in hLGCs. Moreover, SP1 inhibition prevented the stimulation of steroidogenic genes and the increase in LHCGR-LUC reporter activity by hCG. Finally, we provide evidence that a complex formed by SP1 and GATA4 may play a role in the maintenance of LHCGR expression. This report reveals the mechanisms involved in the regulation of the LHCGR and provides experimental data demonstrating that the proximal region of the LHCGR promoter is sufficient to drive the expression of this gene in primary hLGCs.
黄体生成素和人绒毛膜促性腺激素（hCG）与黄体生成素/绒毛膜促性腺激素受体（LHCGR）结合。LHCGR 是维持黄体功能所必需的，但人类黄体细胞中 LHCGR 调节的机制仍不完全清楚。本研究旨在描述从接受体外受精的患者中获得的原代人黄体化颗粒细胞（hLGC）中 LHCGR mRNA 的表达，并通过评估已知作为 hCG 作用标志物的基因的表达来将 LHCGR 表达与 hLGC 对 hCG 的反应相关联。结果表明，LHCGR 表达在新鲜分离的细胞中较低，但在培养中迅速恢复，并且 hCG 维持 LHCGR 表达，提示存在正反馈环。用 hCG 处理可增加 LHCGR-LUC 报告基因的活性，但用卵泡刺激素处理则不行。hCG 处理还可时间依赖性地刺激参与甾体生成的基因的表达。发现 LHCGR 启动子的表达受 SP1 调节，我们证明 SP1 在 hLGC 中高度表达。此外，SP1 抑制可防止 hCG 刺激甾体生成基因和 LHCGR-LUC 报告基因活性的增加。最后，我们提供了证据表明，由 SP1 和 GATA4 形成的复合物可能在 LHCGR 表达的维持中起作用。该报告揭示了 LHCGR 调节的机制，并提供了实验数据，证明 LHCGR 启动子的近端区域足以在原代 hLGC 中驱动该基因的表达。
