Boglino Anaïs, Ponce Marian, Cousin Xavier, Gisbert Enric, Manchado Manuel
Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán (CIAD), PO Box 711, 82010 Mazatlán, Sinaloa, Mexico.
IFAPA Centro El Toruño, Junta de Andalucía, Camino Tiro de Pichón s/n, 11500 El Puerto de Santa María, Cádiz, Spain.
Comp Biochem Physiol B Biochem Mol Biol. 2017 Jan;203:35-46. doi: 10.1016/j.cbpb.2016.08.007. Epub 2016 Sep 10.
The aim of this study was the characterization of transcriptional regulatory pathways mediated by retinoic acid (RA) in Senegalese sole larvae. For this purpose, pre-metamorphic larvae were treated with a low concentration of DEAB, an inhibitor of RALDH enzyme, until the end of metamorphosis. No differences in growth, eye migration or survival were observed. Nevertheless, gene expression analysis revealed a total of 20 transcripts differentially expressed during larval development and only six related with DEAB treatments directly involved in RA metabolism and actions (rdh10a, aldh1a2, crbp1, igf2r, rarg and cyp26a1) to adapt to a low-RA environment. In a second experiment, post-metamorphic larvae were exposed to the all-trans RA (atRA) observing an opposite regulation for those genes involved in RA synthesis and degradation (rdh10a, aldh1a2, crbp1 and cyp26a1) as well as other related with thyroid- (dio2) and IGF-axes (igfbp1, igf2r and igfbp5) to balance RA levels. In a third experiment, DEAB-pretreated post-metamorphic larvae were exposed to atRA and TTNPB (a specific RAR agonist). Both drugs down-regulated rdh10a and aldh1a2 and up-regulated cyp26a1 expression demonstrating their important role in RA homeostasis. Moreover, five retinoic receptors that mediate RA actions, the thyroid receptor thrb, and five IGF binding proteins changed differentially their expression. Overall, this study demonstrates that exogenous RA modulates the expression of some genes involved in the RA synthesis, degradation and cellular transport through RAR-mediated regulatory pathways establishing a negative feedback regulatory mechanism necessary to balance endogenous RA levels and gradients.
本研究的目的是表征塞内加尔鳎幼体中视黄酸（RA）介导的转录调控途径。为此，在变态前期幼体中用低浓度的DEAB（RALDH酶抑制剂）进行处理，直至变态结束。未观察到生长、眼睛迁移或存活方面的差异。然而，基因表达分析显示，在幼体发育过程中共有20个转录本差异表达，其中只有6个与直接参与RA代谢和作用的DEAB处理相关（rdh10a、aldh1a2、crbp1、igf2r、rarg和cyp26a1），以适应低RA环境。在第二个实验中，变态后幼体暴露于全反式视黄酸（atRA），观察到参与RA合成和降解的那些基因（rdh10a、aldh1a2、crbp1和cyp26a1）以及其他与甲状腺轴（dio2）和IGF轴（igfbp1、igf2r和igfbp5）相关的基因呈现相反的调控，以平衡RA水平。在第三个实验中，将经DEAB预处理的变态后幼体暴露于atRA和TTNPB（一种特异性RAR激动剂）。两种药物均下调rdh10a和aldh1a2，并上调cyp26a1的表达，证明它们在RA稳态中发挥重要作用。此外，介导RA作用的五种视黄酸受体、甲状腺受体thrb以及五种IGF结合蛋白的表达发生了不同程度的变化。总体而言，本研究表明外源性RA通过RAR介导的调控途径调节参与RA合成、降解和细胞转运的一些基因的表达，建立了平衡内源性RA水平和梯度所需的负反馈调节机制。
