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- Title
PPARα and PPARγ Coactivation Rapidly Induces Egr-1 in the Nuclei of the Dorsal and Ventral Urinary Bladder and Kidney Pelvis Urothelium of Rats.
- Authors
Lihme Egerod, Frederikke; Eldrup Svendsen, Jette; Hinley, Jennifer; Southgate, Jennifer; Bartels, Annette; Brünner, Nils; Oleksiewicz, Martin B.
- Abstract
To facilitate studies of the rat bladder carcinogenicity of dual-acting PPARα+γ agonists, we previously identified the Egr-1 transcription factor as a candidate carcinogenicity biomarker and developed rat models based on coadministration of commercially available specific PPARα and PPARγ agonists. Immunohistochemistry for Egr-1 with a rabbit monoclonal antibody demonstrated that male vehicle-treated rats exhibited minimal urothelial expression and specifically, no nuclear signal. In contrast, Egr-1 was induced in the nuclei of bladder, as well as kidney pelvis, urothelia within one day (2 doses) of oral dosing of rats with a combination of 8 mg/kg rosiglitazone and 200 mg/kg fenofibrate (specific PPARγ and PPARα agonists, respectively). These findings were confirmed by Western blotting using a different Egr-1 antibody. Egr-1 was induced to similar levels in the dorsal and ventral bladder urothelium, arguing against involvement of urinary solids. Egr-1 induction sometimes occurred in a localized fashion, indicating physiological microheterogeneity in the urothelium. The rapid kinetics supported that Egr-1 induction occurred as a result of pharmacological activation of PPARα and PPARγ, which are coexpressed at high levels in the rat urothelium. Finally, our demonstration of a nuclear localization supports that the Egr-1 induced by PPARα and PPARγ coactivation in the rat urothelium may be biologically active.
- Publication
Toxicologic Pathology, 2009, Vol 37, Issue 7, p947
- ISSN
0192-6233
- Publication type
Article
- DOI
10.1177/0192623309351723