STAT3 involvement in the acute phase-related expression of the rat haptoglobin gene

Turpentine-induced acute-phase (AP) response in rats is followed by transcr iptional activation of the haptoglobin (Hp) gene in liver. Analysing the pr omoter sequence of the rat Hp gene we postulated an involvement of Signal T ransducer and Activator of Transcription 3 (STAT3) in the regulation of thi s process. Results obtained by using a combination of Western immunoblot an d DNA-binding assays revealed AP-induced binding of constitutive 86kD- and inducible 91kD-STAT3 isoforms to the rat Hp gene inducible promoter element . On the basis of these data we assumed that AP-related interactions of the se two STAT3 isoforms correlates with an activated transcriptional status o f the rat Hp gene.