Figure 3

AhR is necessary for Cyp1a1 induction and caspase-3 cascade activation in B[a]P-treated mandibular condyles. (A,B) Detection of Cyp1a1 mRNA (A) and protein (B) in mandibular condyles from WT and AhR^−/− mice treated with B[a]P (+ , oral gavage, 120 mg/kg) by qPCR and Western blotting, respectively. Staining by β-actin antibody was performed as a control of same amount protein loading. Full-length blots are presented in Supplementary Figure S2. (C) Representative sections from performing IHC staining to detect Cyp1a1, AhR and caspase-3 protein expression in mandibular condyles from WT and AhR^−/− mice treated with B[a]P (+ , oral gavage, 120 mg/kg). Scale bar = 100 μm. The number of Cyp1a1⁺ and active caspase-3⁺ cells in the posterior thirds and central of the mandibular condylar cartilages resected from AhR^−/− and WT mice administered with B[a]P were compared. (D) ATDC5 cells were incubated in the presence of 10 μM concentration B[a]P for 6, 12, 24, 48 h. Whole cell lysates were respectively subjected to immunoblot analyses to detect the apoptotic key marker cleaved caspase-3. Detection by β-actin antibody was performed as a control of same amount protein loading. Full-length blots are presented in Supplementary Figure S2. (E) Immunoblot analyses of cleaved caspase-3 derived from primary mandibular chondrocytes isolated from WT and AhR^−/− mice treated with or without AhR antagonist B[a]P (+ , oral gavage, 120 mg/kg). Staining of β-actin primary antibody was detected as a loading control. Full-length blots are presented in Supplementary Figure S2.