2,3,7,8-Tetrachlorodibenzo-p-dioxin elicits aryl hydrocarbon receptor-mediated apoptosis in the avian DT40 pre-B-cell line through activation of caspases 9 and 3.
The halogenated aromatic hydrocarbon 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is known to induce immunotoxicity, but relatively little is known regarding its effects on B-lymphocytes, and on avian B-cells in particular. In this study, the avian bursal pre-B-cell line DT40 was exposed to TCDD ranging from 1 to 500 nM for 1 and 6 h. At 100 nM, TCDD caused a significant increase in the number of apoptotic cells, as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) assay, and induced the expression of the chicken cytochrome P450 1A4 (CYP1A4) mRNA, a hallmark of TCDD exposure. TCDD induced transient upregulation of aryl hydrocarbon receptor (AhR) mRNA. At 100 nM, both caspase 3 and caspase 9 were transiently upregulated after 1 h, but returned to normal levels after 6 h of exposure. Challenge with TCDD after AhR blockade with resveratrol, a competitive AhR antagonist, prevented changes in caspases 3 and 9 and in the AhR message itself, suggesting that the effects of TCDD were mediated via the AhR. TCDD did not cause significant changes in the relative gene expression of caspase 8, Bcl-2 and Bcl-xL. We conclude that avian DT40 pre-B-cells exposed to TCDD are susceptible to apoptosis, likely through activation of executioner caspase 3.
Puebla-Osorio
N
N
Department of Poultry Science, Texas A and M University, College Station, TX 77843-2472, USA.
Ramos
K S
KS
Falahatpisheh
M H
MH
Smith
R
R
Berghman
L R
LR
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis / Q000235:genetics; D030161:Avian Proteins / Q000096:biosynthesis / Q000235:genetics; D001402:B-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002645:Chickens; D017931:DNA Primers / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D020287:In Situ Nick-End Labeling; D010088:Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D030161:Avian Proteins; D017931:DNA Primers; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D010088:Oxidoreductases; D001189:Aryl Hydrocarbon Hydroxylases; C416342:CYP1A4 protein, Gallus gallus; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases