Oride Aki, Kanasaki Haruhiko, Mijiddorj Tselmeg, Sukhbaatar Unurjargal, Miyazaki Kohji
Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo 693-8501, Japan.
Endocr J. 2014;61(4):335-42. doi: 10.1507/endocrj.ej13-0411. Epub 2014 Jan 16.
Trichostatin A (TSA) is a selective inhibitor of mammalian histone deacetylase. In the present study, TSA was found to selectively increase gene expression of the pituitary gonadotropin β-subunit of follicle-stimulating hormone (FSH). Stimulation of mouse pituitary gonadotroph cell lines, LβT2, with TSA for 24 h resulted in no change in mRNA expression of the α- and LHβ-subunit. On the other hand, FSHβ-subunit mRNA expression was significantly increased in a dose-dependent fashion. Similarly, specific induction of the FSHβ-subunit gene with TSA stimulation was observed in primary cultures of rat pituitary cells. Histone acetylation in whole cell lysates of LβT2 cells was significantly increased after TSA treatment, but not gonadotropin-releasing hormone (GnRH) treatment. The effect of TSA on FSHβ mRNA expression was prominent compared to that of GnRH; however, TSA-stimulated FSHβ mRNA expression was significantly reduced with combined TSA and GnRH treatment. TSA caused a slight increase in extracellular signal-regulated kinase (ERK) phosphorylation, while GnRH-increased ERK phosphorylation was potentiated in the presence of TSA. In addition, TSA, but not GnRH, significantly stimulated gene expression of retinaldehyde dehydrogenase 1 (RALDH1), a retinoic acid (RA) synthesizing enzyme involved in cell differentiation. These findings demonstrate that TSA specifically increases FSHβ subunit gene expression with a concomitant increase in whole cell histone acetylation. Moreover, although GnRH is a stimulator of FSHβ gene expression, it interfered with the stimulatory effect of TSA on FSHβ mRNA expression, without modification of TSA-increased whole cell histone acetylation. This suggests that the mechanisms of TSA and GnRH-induced gonadotropin subunit gene expression are entirely distinct.
曲古抑菌素A（TSA）是一种哺乳动物组蛋白脱乙酰酶的选择性抑制剂。在本研究中，发现TSA可选择性增加垂体促卵泡激素（FSH）β亚基的基因表达。用TSA刺激小鼠垂体促性腺激素细胞系LβT2 24小时，α亚基和促黄体生成素β亚基（LHβ）的mRNA表达没有变化。另一方面，FSHβ亚基的mRNA表达以剂量依赖性方式显著增加。同样，在大鼠垂体细胞的原代培养物中也观察到TSA刺激对FSHβ亚基基因的特异性诱导。TSA处理后，LβT2细胞全细胞裂解物中的组蛋白乙酰化显著增加，但促性腺激素释放激素（GnRH）处理后没有增加。与GnRH相比，TSA对FSHβ mRNA表达的影响更为显著；然而，TSA和GnRH联合处理可显著降低TSA刺激的FSHβ mRNA表达。TSA导致细胞外信号调节激酶（ERK）磷酸化略有增加，而在TSA存在的情况下，GnRH增加的ERK磷酸化增强。此外，TSA而非GnRH可显著刺激视黄醛脱氢酶1（RALDH1）的基因表达，RALDH1是一种参与细胞分化的视黄酸（RA）合成酶。这些发现表明，TSA可特异性增加FSHβ亚基基因表达，并伴随全细胞组蛋白乙酰化增加。此外，尽管GnRH是FSHβ基因表达的刺激物，但它干扰了TSA对FSHβ mRNA表达的刺激作用，而不改变TSA增加的全细胞组蛋白乙酰化。这表明TSA和GnRH诱导促性腺激素亚基基因表达的机制完全不同。
