PDF(Pubmed)
Abstract：
Somatic growth in vertebrates is mainly controlled by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The role of epigenetic mechanisms in regulating this axis in fish is far from being understood. This work aimed to optimize and evaluate the use of short-term culture of pituitary and liver explants from a farmed fish, the gilthead seabream Sparus aurata, for studying epigenetic mechanisms involved in GH/IGF-I axis regulation. Our results on viability, structure, proliferation, and functionality of explants support their use in short-term assays. Pituitary explants showed no variation in gh expression after exposure to the DNA methylation inhibitor decitabine (5-Aza-2\'-deoxycytidine; DAC), despite responding to DAC by changing dnmt3bb and tet1 expression, and TET activity, producing an increase in overall DNA hydroxymethylation. Conversely, in liver explants, DAC had no effects on dnmt s and tet s expression or activity, but modified the expression of genes from the GH-IGF-I axis. In particular, the expression of igfbp2a was increased and that of igfbp4, ghri and ghrii was decreased by DAC as well as by genistein, which is suggestive of impaired growth. While incubation of liver explants with S-adenosylmethionine (SAM) produced no clear effects, it is proposed that nutrients must ensure the methylation milieu within the liver in the fish to sustain proper growth, which need further in vivo verification. Pituitary and liver explants from S. aurata can be further used as described herein for the screening of inhibitors or activators of epigenetic regulators, as well as for assessing epigenetic mechanisms behind GH-IGF-I variation in farmed fish.
摘要：
脊椎动物的体细胞生长主要受生长激素（GH）/胰岛素样生长因子I（IGF-I）轴的控制。表观遗传机制在鱼类中调节该轴的作用尚不清楚。这项工作旨在优化和评估使用短期培养的垂体和肝脏外植体从养殖鱼，金头seabreamSparusaurata,用于研究与GH/IGF-I轴调节有关的表观遗传机制。我们关于生存能力的结果，结构,扩散,和外植体的功能支持它们在短期测定中的使用。垂体外植体暴露于DNA甲基化抑制剂地西他滨（5-Aza-2'-脱氧胞苷；DAC）后，gh表达无变化，尽管通过改变dnmt3bb和tet1表达来响应DAC，和TET活动，产生整体DNA羟甲基化的增加。相反，在肝脏外植体中，DAC对dnmt和tet的表达或活性没有影响，而是改变了GH-IGF-I轴基因的表达。特别是,DAC和染料木素使igfbp2a的表达增加，而igfbp4，ghri和ghrii的表达减少，这表明增长受损。虽然肝脏外植体与S-腺苷甲硫氨酸（SAM）的孵育没有产生明显的影响，建议营养素必须确保鱼类肝脏内的甲基化环境以维持适当的生长，这需要进一步的体内验证。如本文所述，来自S.aurata的垂体和肝脏外植体可以进一步用于筛选表观遗传调节剂的抑制剂或激活剂，以及评估养殖鱼类GH-IGF-I变异背后的表观遗传机制。
