Transcriptional signature of the developing rat testes and ovaries following embryonic exposure to 2,3,7,8-TCDD

We determined global gene changes in immature ovaries and testes in response to an in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. Microarray analysis was performed using testes and ovaries of the dioxin-exposed dams’ offspring. One hundred and thirteen genes were differentially expressed in ovaries and 56 genes in testes of 14 and 5 days-old, respectively. Real-time PCR was used to validate and extend data using RNA extracted from 5 to 145-day old rat testes and 3 to 25-day old rat ovaries. A single gene of the classic dioxin battery, i.e., the repressor of the aryl hydrocarbon receptor (Ahrr) was found altered in testes. In contrast, several of them including Cyp1a1, Cyp1b1, Nqo1, and Ahrr were found up-regulated in ovary, pituitary (a different endocrine organ) and liver. In addition to Ahrr, we identified 6 genes targeted by dioxin in both gonads, including the chemokines Cxcl4, Ccl5. Ccl5 gene expression levels were also regulated in pituitary and liver, so as pituitary Cxcl4. Four genes targeted by TCDD in testis and meeting stringent criteria were further surveyed. It included 2 genes with no previous reported function in testis, Art2b, Gzmf, Hpgds and Fgf13. Fgf13 was down-regulated in testis, and pituitary but not in ovary or liver. Interestingly, Art2b and Gzmf were up-regulated in testis, liver and pituitary but not ovary. Finally, Hpgds was unique in that expressed in various tissues it was regulated by TCDD in the gonads but not in the other tissues studied.本研究旨在解析未成熟卵巢与睾丸在子宫内暴露于2,3,7,8-四氯二苯并对二噁英（2,3,7,8-tetrachlorodibenzo-p-dioxin，下文简称TCDD）后的全基因组表达变化。本研究采用TCDD暴露孕鼠子代的睾丸与卵巢组织开展基因芯片（Microarray）分析，结果显示，在14日龄子代卵巢与5日龄子代睾丸中，分别鉴定出113个与56个差异表达基因。为验证并拓展芯片分析结果，本研究提取了5至145日龄大鼠睾丸以及3至25日龄大鼠卵巢的RNA，通过实时定量PCR（Real-time PCR）完成后续验证。经典二噁英应答基因簇中，仅芳香烃受体阻遏蛋白（Ahrr，aryl hydrocarbon receptor repressor）这1个基因在睾丸组织中出现表达异常；与之相反，在卵巢、垂体（另一内分泌器官）与肝脏组织中，包括Cyp1a1、Cyp1b1、Nqo1及Ahrr在内的多个经典二噁英应答基因均呈现上调表达。除Ahrr外，本研究还鉴定出6个在两种性腺组织中均受TCDD调控的基因，其中包括趋化因子Cxcl4与Ccl5。Ccl5基因在垂体与肝脏中的表达水平同样受到TCDD调控，垂体中的Cxcl4基因表达亦呈现类似调控模式。针对在睾丸中受TCDD调控且满足严格筛选标准的4个基因，本研究开展了进一步验证分析，该4个基因分别为Art2b、Gzmf、Hpgds及Fgf13，其中2个基因此前尚未见其在睾丸中发挥功能的相关报道。Fgf13在睾丸与垂体中呈现下调表达，但在卵巢与肝脏中无显著表达变化。值得注意的是，Art2b与Gzmf在睾丸、肝脏与垂体中均呈现上调表达，但在卵巢中无显著变化。最后，Hpgds的调控模式较为特殊：尽管其在多种组织中均有表达，但仅在性腺组织中受TCDD调控，而在本研究分析的其他组织中均无此调控效应。