Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada.
PLoS One. 2014 Apr 21;9(4):e95351. doi: 10.1371/journal.pone.0095351. eCollection 2014.
This study examined the similarities in microRNA profiles between fasted and fluoxetine (FLX) exposed zebrafish and downstream target transcripts and biological pathways. Using a custom designed microarray targeting 270 zebrafish miRNAs, we identified 9 differentially expressed miRNAs targeting transcripts in biological pathways associated with anabolic metabolism, such as adipogenesis, cholesterol biosynthesis, triacylglycerol synthesis, and insulin signaling. Exposure of female zebrafish to 540 ng/L FLX, an environmentally relevant concentration and a known metabolic repressor, increased specific miRNAs indicating greater inhibition of these pathways in spite of continued feeding. Further examination revealed two specific miRNAs, dre-let-7d and dre-miR-140-5p, were predicted in silico to bind to a primary regulator of metabolism, adenosine monophosphate-activated protein kinase (AMPK), and more specifically the two isoforms of the catalytic subunit, AMPKα1 and α2, respectively. Real-time analysis of the relative transcript abundance of the α1 and α2 mRNAs indicated a significant inverse relationship between specific miRNA and target transcript. This suggests that AMPK-related pathways may be compromised during FLX exposure as a result of increased miRNA abundance. The mechanism by which FLX regulates miRNA abundance is unknown but may be direct at the liver. The serotonin transporter, slc6a4, is the target of FLX and other selective serotonin reuptake inhibitors (SSRI) and it was found to be expressed in the liver, although treatment did not alter expression of this transporter. Exposure to FLX disrupts key hepatic metabolic pathways, which may be indicative of reduced overall fitness and these effects may be linked to specific miRNA abundance. This has important implications for the heath of fish because concentrations of SSRIs in aquatic ecosystems are continually increasing.
本研究考察了禁食和氟西汀(FLX)暴露的斑马鱼之间的 microRNA 谱的相似性,以及下游靶转录物和生物学途径。使用针对 270 种斑马鱼 microRNA 的定制微阵列,我们鉴定出了 9 种差异表达的 microRNA,靶向与合成代谢相关的生物途径的靶转录物,如脂肪生成、胆固醇生物合成、三酰基甘油合成和胰岛素信号传导。暴露于 540ng/L FLX(一种环境相关浓度和已知的代谢抑制剂)的雌性斑马鱼增加了特定的 microRNA,表明尽管继续进食,但这些途径的抑制作用更大。进一步的研究表明,两种特定的 microRNA,dre-let-7d 和 dre-miR-140-5p,被预测为代谢关键调节剂腺苷单磷酸激活蛋白激酶(AMPK)的结合物,更具体地说是其两个催化亚基,AMPKα1 和α2 的结合物。相对 AMPKα1 和α2 mRNA 转录物丰度的实时分析表明,特定 microRNA 和靶转录物之间存在显著的负相关关系。这表明在 FLX 暴露期间,AMPK 相关途径可能因 microRNA 丰度增加而受损。FLX 调节 microRNA 丰度的机制尚不清楚,但可能直接在肝脏中起作用。5-羟色胺转运体 slc6a4 是 FLX 和其他选择性 5-羟色胺再摄取抑制剂(SSRI)的靶标,虽然在肝脏中发现了这种转运体的表达,但治疗并未改变这种转运体的表达。FLX 暴露会破坏关键的肝脏代谢途径,这可能表明整体健康状况下降,这些影响可能与特定的 microRNA 丰度有关。这对鱼类的健康具有重要意义,因为水生生态系统中 SSRIs 的浓度不断增加。