Transcriptional control of CYP1B1 and CYP1C1 genes in Zebrafish embryo

• Main Authors: Hou-Chu Yin, 殷厚珠
• Other Authors: Chin-Hwa Hu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/04744318107227205586

博士 === 國立臺灣海洋大學 === 生物科技研究所 === 97 === Abstract Cytochrome P450 1B1 （CYP1B1） is a heme-containing monooxygenase that metabolizes various polycyclic aromatic hydrocarbons （PAHs） and arylamines, as well as retinoic acid and steroid hormones. Here we presented that zebrafish CYP1B1 is constitutively expressed in embryonic ocular cells, diencephalons, and midbrain-hindbrain boundary during pharyngula stage. After hatching, the constitutive-type of CYP1B1 transcription is attenuated. TCDD exposure elicited de novo CYP1B1 transcription in pharyngeal arches and heart tissues at larval stage. Knockdown of AHR2 in zebrafish embryos abolished the induction of CYP1B1 by TCDD, but did not eliminate the basal level of CYP1B1 transcription in ocular cells. It suggests that the constitutive and TCDD-inducible types of CYP1B1 transcriptions are modulated by distinct pathways and exhibits different tissue specificity. We have also investigated the role of CYP1B1 in TCDD-mediated embryonic toxicity. Here we presented that CYP1B1 knockdown did not prevent TCDD-induced pericardial edema and cranial defects, suggesting that CYP1B1 does not involve in the developmental toxicity of dioxin. CYP1C is a novel CYP1 subfamily that is constitutively expressed in a broad range of adult fish tissues and developing embryos. Like other CYP1 members, CYP1C genes can be induced by various polycyclic aromatic hydrocarbons. However, the pattern of CYP1C expression during early stages of development has not been fully addressed. Previously, we have cloned a complete CYP1C1 cDNA from zebrafish embryo （GenBank accession number AY_928186）. Here we reported that zebrafish CYP1C1 exhibited a restricted expression pattern dominantly in the vasculature of the aortic arches at late pharyngula stage. This basal type of transcription reached highest level at 48-72 hpf and subsequently its expression attenuated gradually. TCDD exposure elicited a high level of CYP1C1 transcription. The function of AHR1A, AHR1B and AHR2 on CYP1 tanscription has also been investigated. Blocking AHR1A only had mild effects on TCDD-induced CYP1A1 and CYP1C1 transcription, but had no significant effect on CYP1B1 transcription. Knockdown AHR1B reduced both constitutive-type and TCDD-induced CYP1A1 transcription, but did not change CYP1C1 expression. Blocking AHR2 could completely inhibite TCDD-induced CYP1A1, CYP1B1 and CYP1C1 transcriptions and also reduced significant level of their constitute-type transcriptions in non-ocular tissues.