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Aryl hydrocarbon receptor‐dependence of dioxin effects on constitutive mouse hepatic cytochromes P450 and growth hormone signaling components
Author(s) -
Riddick David S,
Lee Chunja
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1102.5
Subject(s) - aryl hydrocarbon receptor , cyp1b1 , medicine , endocrinology , cytochrome p450 , agonist , aryl hydrocarbon receptor nuclear translocator , receptor , biology , signal transduction , stat protein , chemistry , stat3 , gene , transcription factor , microbiology and biotechnology , biochemistry , metabolism
The aryl hydrocarbon receptor (AHR) has physiological roles in the absence of exposure to exogenous ligands and mediates adaptive and toxic responses to the environmental pollutant, 2,3,7,8‐tetracholorodibenzo ‐p‐ dioxin (TCDD). A readily metabolized AHR agonist, 3‐methylcholanthrene, disrupts expression of mouse hepatic growth hormone (GH) signaling components and suppresses cytochrome P450 2D9 ( Cyp2d9 ), a male‐specific gene controlled by pulsatile GH via signal transducer and activator of transcription 5b (STAT5b). Using TCDD as an essentially non‐metabolized AHR agonist and Ahr −/− mice as a model to determine the AHR‐dependence of biological responses, we show that two mouse hepatic STAT5b target genes, Cyp2d9 and major urinary protein 2 ( Mup2 ), are suppressed by TCDD in an AHR‐dependent manner. TCDD also decreased hepatic mRNA levels for GH receptor, Janus kinase 2, and STAT5a/b with AHR‐dependence. Without inducing selected hepatic inflammatory markers, TCDD caused AHR‐dependent induction of Cyp1a1 and NADPH‐cytochrome P450 oxidoreductase ( Por ) and suppression of Cyp3a11 . In vehicle‐treated mice, basal mRNA levels for CYP2D9, CYP3A11, POR, serum amyloid protein P, and MUP2 were influenced by Ahr genetic status. We conclude that AHR activation per se leads to dysregulation of hepatic GH signaling components and suppression of some, but not all, STAT5b target genes. [Support: CIHR]