FIGURE SUMMARY
- Title
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The anti-inflammatory drug leflunomide is an agonist of the aryl hydrocarbon receptor
- Authors
- O'Donnell, E.F., Saili, K.S., Koch, D.C., Kopparapu, P.R., Farrer, D., Bisson, W.H., Mathew, L.K., Sengupta, S., Kerkvliet, N.I., Tanguay, R.L., and Kolluri, S.K.
- Source
- Full text @ PLoS One
Leflunomide induces aryl hydrocarbon receptor dependent expression of CYP1A1 in zebrafish. (A) One-cell stage wildtype embryos were injected with a control morpholino or AhR2 morpholino. At 6 hpf, the zebrafish were exposed to 10 μM leflunomide for 3 days. Immunohistochemistry for CYP1A, a known AhR2 target gene in zebrafish, demonstrated that leflunomide induces CYP1A expression in an AhR2 dependent manner. (B) Exposure of zebrafish to A771726 at doses of either 1 or 10 μM did not increase CYP1A expression. |
Leflunomide acts through the AhR to inhibit regeneration in an AhR-dependent manner. Amputation of the caudal zebrafish fin is a well-established model used to study tissue regeneration; TCDD is known to inhibit this regeneration process. To investigate whether leflunomide behaves like TCDD to inhibit epimorphic regeneration through the AhR, one-cell stage embryos were injected with a control or AhR2 morpholino, and the caudal fin was amputated at 48 hpf, followed by immediate exposure to vehicle or 25 μM leflunomide. (A) After 3 days, images of the fins were taken with brightfield microscopy. In addition, immunohistochemistry for CYP1A confirmed that leflunomide activated AhR2 (dotted line indicates the plane of amputation). (B) Although A771726 did not appear to activate the AhR in vivo or in our cell culture models, we investigated whether the compound could also inhibit fin regeneration, as inhibition of cell growth via disruption of de novo pyrimidine biosynthesis inhibition is a well-characterized endpoint of A771726. Amputated zebrafish were exposed to vehicle or 10 μM A771726. Exposure to 10 µM A771726 did not influence the regenerative process. |
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Full text @ PLoS One