The transcriptional response to oxidative stress during vertebrate development: effects of tert-butylhydroquinone and 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Oxidative stress is an important mechanism of chemical toxicity, contributing to teratogenesis and to cardiovascular and neurodegenerative diseases. Developing animals may be especially sensitive to chemicals causing oxidative stress. The developmental expression and inducibility of anti-oxidant defenses through activation of NF-E2-related factor 2 (NRF2) affect susceptibility to oxidants, but the embryonic response to oxidants is not well understood. To assess the response to chemically mediated oxidative stress and how it may vary during development, zebrafish embryos, eleutheroembryos, or larvae at 1, 2, 3, 4, 5, and 6 days post fertilization (dpf) were exposed to DMSO (0.1%), tert-butylhydroquinone (tBHQ; 10 µM) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 2 nM) for 6 hr. Transcript abundance was assessed by real-time qRT-PCR and microarray. qRT-PCR showed strong (4- to 5-fold) induction of gstp1 by tBHQ as early as 1 dpf. tBHQ also induced gclc (2 dpf), but not sod1, nqo1, or cyp1a. TCDD induced cyp1a but none of the other genes. Microarray analysis showed that 1477 probes were significantly different among the DMSO-, tBHQ-, and TCDD-treated eleutheroembryos at 4 dpf. There was substantial overlap between genes induced in developing zebrafish and a set of marker genes induced by oxidative stress in mammals. Genes induced by tBHQ in 4-dpf zebrafish included those involved in glutathione synthesis and utilization, signal transduction, and DNA damage/stress response. The strong induction of hsp70 determined by microarray was confirmed by qRT-PCR and by use of transgenic zebrafish expressing enhanced green fluorescent protein (EGFP) under control of the hsp70 promoter. Genes strongly down-regulated by tBHQ included mitfa, providing a molecular explanation for the loss of pigmentation in tBHQ-exposed embryos. These data show that zebrafish embryos are responsive to oxidative stress as early as 1 dpf, that responsiveness varies with development in a gene-specific manner, and that the oxidative stress response is substantially conserved in vertebrate animals.
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Mark E
ME
Hahn
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America.
Andrew G
AG
McArthur
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Sibel I
SI
Karchner
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Diana G
DG
Franks
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Matthew J
MJ
Jenny
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Alicia R
AR
Timme-Laragy
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
John J
JJ
Stegeman
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Bruce R
BR
Woodin
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America.
Michael J
MJ
Cipriano
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America.
Elwood
E
Linney
D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000254:growth & development; D000975:Antioxidants / Q000633:toxicity; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D006873:Hydroquinones / Q000633:toxicity*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D013723:Teratogens / Q000633:toxicity; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
D000975:Antioxidants; D006873:Hydroquinones; D000072317:Polychlorinated Dibenzodioxins; D013723:Teratogens; D029961:Zebrafish Proteins; C018855:2-tert-butylhydroquinone