Minegishi T, Hirakawa T, Kishi H, Abe K, Ibuki Y, Miyamoto K
Department of Obstetrics and Gynecology, School of Medicine, Gunma University, Maebashi, Gunma, 371-8511, Japan.
Arch Biochem Biophys. 2000 Jan 1;373(1):203-10. doi: 10.1006/abbi.1999.1528.
The present study was undertaken to identify the mechanisms underlying the effect of retinoic acid (RA) on the luteinizing hormone receptor (LH-R) in rat granulosa cells. Treatment with FSH produced a substantial increase in LH-R mRNA level, as was expected, while concurrent treatment with increasing concentrations of RA brought about dose-dependent decreases in FSH-induced LH-R mRNA. RA, either alone or in combination with FSH, did not affect intracellular cAMP levels, while it inhibited the effect of 8-Br-cAMP on LH-R mRNA production. Whether the effect of RA and FSH on LH-R mRNA levels was the result of decreased transcription and/or altered mRNA stability was also investigated. The rate of LH receptor mRNA gene transcription, assessed by nuclear run-on transcription assay, was inhibited by the addition of RA. The effect of RA on LH-R mRNA stability was determined by measuring the decay of LH receptor mRNA under conditions known to inhibit transcription. The decay curves for the 5.4-kb LH-R mRNA transcript showed a significant decrease after the addition of RA. It may be possible that RA not only inhibits FSH-induced transcription but also stimulates the production of destabilizing factors for the LH-R mRNA. These findings assist in understanding the molecular mechanism underlying the effect of RA on reproductive function in rat granulosa cells.
本研究旨在确定维甲酸（RA）对大鼠颗粒细胞中促黄体生成素受体（LH-R）作用的潜在机制。正如预期的那样，用促卵泡激素（FSH）处理可使LH-R mRNA水平大幅增加，而同时用浓度递增的RA处理则导致FSH诱导的LH-R mRNA呈剂量依赖性降低。单独使用RA或与FSH联合使用时，均不影响细胞内cAMP水平，但它抑制了8-溴-cAMP对LH-R mRNA产生的作用。还研究了RA和FSH对LH-R mRNA水平的影响是转录减少和/或mRNA稳定性改变的结果。通过核转录分析评估的LH受体mRNA基因转录速率，在添加RA后受到抑制。通过在已知抑制转录的条件下测量LH受体mRNA的衰减来确定RA对LH-R mRNA稳定性的影响。5.4 kb LH-R mRNA转录本的衰减曲线在添加RA后显示出显著下降。RA不仅可能抑制FSH诱导的转录，还可能刺激LH-R mRNA不稳定因子的产生。这些发现有助于理解RA对大鼠颗粒细胞生殖功能作用的分子机制。
