PANCREATITIS-ASSOCIATED PROTEIN-I (PAP-I), AN ACUTE-PHASE PROTEIN-INDUCED BY CYTOKINES - IDENTIFICATION OF 2 FUNCTIONAL INTERLEUKIN-6 RESPONSE ELEMENTS IN THE RAT PAP-I PROMOTER REGION

Expression of the pancreatitis-associated protein I (PAP I), an exocri ne pancreatic protein, increases rapidly and strongly in acinar cells during the acute phase of pancreatitis, This is reminiscent of the res ponse to stress of acute phase proteins, We have previously demonstrat ed that serum factors from rats with acute pancreatitis, but not from healthy rats, could induce endogenous PAP I gene expression in the aci nar cell Line AR-42J (Dusetti, N., Mallo, G., Dagorn, J.-C., Iovanna, J. L. (1994) Biochem, Biophys, Res, Commun, 204, 238-243), In the pres ent work, we have evaluated the influence of several mediators of infl ammation on rat PAP I gene transcription in these cells, Tumor necrosi s factor alpha induced an increase in PAP I mRNA expression, and inter feron gamma caused an even greater increase in PAP I mRNA level, These stimulations were antagonized by dexamethasone. Interleukin (IL)-1, I L-6, or dexamethasane alone were ineffective, Combinations of IL-1 wit h n-6 or dexamethasone were also ineffective, IL-6 and dexamethasone t ogether induced a marked stimulation of PAP I gene transcription, and this effect was slightly attenuated by IL-1, To analyze the cis-regula tory elements responsible for the induction of transcription, we fused a 1,2-kilobase segment of the rat PAP I promoter to the chloramphenic ol acetyltransferase (CAT) gene as reporter, The resultant chimeric DN A was transfected into AR-42J cells. Addition of IL-6 or dexamethasone was ineffective, whereas their mixture increased the CAT activity 12 times. Progressive deletions of the PAP I promoter were then fused to the CAT gene, and the constructs were transfected to AR-42J cells, A l a-fold increase in CAT activity was seen upon IL-6/dexamethasane treat ment with constructs containing more than 274 base pairs upstream from the cap site, In that region, two sequences are similar to the canoni cal IL-6 response element, Site-directed mutagenesis of these regions strongly decreased induction, showing that they were functional, PAP I should therefore be classified among acute phase proteins of class 2, whose expression is increased by IL-6 acting in combination with gluc ocorticoids.