Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543.
Toxicol Sci. 2014 Jun;139(2):381-95. doi: 10.1093/toxsci/kfu052. Epub 2014 Mar 27.
The aryl hydrocarbon receptor repressor (AHRR) is a transcriptional repressor of aryl hydrocarbon receptor (AHR) and hypoxia-inducible factor (HIF) and is regulated by an AHR-dependent mechanism. Zebrafish (Danio rerio) possess two AHRR paralogs; AHRRa regulates constitutive AHR signaling during development, whereas AHRRb regulates polyaromatic hydrocarbon-induced gene expression. However, little is known about the endogenous roles and targets of AHRRs. The objective of this study was to elucidate the role of AHRRs during zebrafish development using a loss-of-function approach followed by gene expression analysis. Zebrafish embryos were microinjected with morpholino oligonucleotides against AHRRa or AHRRb to knockdown AHRR protein expression. At 72 h postfertilization (hpf), microarray analysis revealed that the expression of 279 and 116 genes was altered by knockdown of AHRRa and AHRRb, respectively. In AHRRa-morphant embryos, 97 genes were up-regulated and 182 genes were down-regulated. Among the down-regulated genes were several related to photoreceptor function, including cone-specific genes such as several opsins (opn1sw1, opn1sw2, opn1mw1, and opn1lw2), phosphodiesterases (pde6H and pde6C), retinol binding protein (rbp4l), phosducin, and arrestins. Down-regulation was confirmed by RT-PCR and with samples from an independent experiment. The four genes tested (opn1sw1, pde6H, pde6C, and arr3b) were not inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin. AHRRa knockdown also caused up-regulation of embryonic hemoglobin (hbbe3), suggesting a role for AHRR in regulating hematopoiesis. Knockdown of AHRRb caused up-regulation of 31 genes and down-regulation of 85 genes, without enrichment for any specific biological process. Overall, these results suggest that AHRRs may have important roles in development, in addition to their roles in regulating xenobiotic signaling.
芳香烃受体阻遏物 (AHRR) 是芳香烃受体 (AHR) 和缺氧诱导因子 (HIF) 的转录阻遏物，受 AHR 依赖性机制调节。斑马鱼 (Danio rerio) 拥有两个 AHRR 同源物; AHRRa 在发育过程中调节组成型 AHR 信号传导，而 AHRRb 调节多环芳烃诱导的基因表达。然而，关于 AHRRs 的内源性作用和靶标知之甚少。本研究旨在通过功能丧失方法结合基因表达分析阐明 AHRRs 在斑马鱼发育过程中的作用。用针对 AHRRa 或 AHRRb 的 morpholino 寡核苷酸对斑马鱼胚胎进行显微注射，以敲低 AHRR 蛋白表达。受精后 72 小时 (hpf)，微阵列分析显示，AHRRa 和 AHRRb 敲低分别导致 279 和 116 个基因的表达发生改变。在 AHRRa 突变体胚胎中，97 个基因上调，182 个基因下调。下调的基因中有几个与光感受器功能有关，包括视锥特异性基因，如几种视蛋白(opn1sw1、opn1sw2、opn1mw1 和 opn1lw2)、磷酸二酯酶(pde6H 和 pde6C)、视黄醇结合蛋白(rbp4l)、磷蛋白和 arrestins。通过 RT-PCR 和独立实验中的样本进行了下调验证。测试的四个基因(opn1sw1、pde6H、pde6C 和 arr3b)不能被 2,3,7,8-四氯二苯并对二恶英诱导。AHRRa 敲低也导致胚胎血红蛋白 (hbbe3) 的上调，表明 AHRR 在调节造血方面发挥作用。AHRRb 敲低导致 31 个基因上调和 85 个基因下调，没有任何特定的生物学过程富集。总的来说，这些结果表明 AHRRs 除了在调节异生物质信号方面的作用外，在发育过程中也可能具有重要作用。
