Faniello MC, Chirico G, Quaresima B, Cuda G, Allevato G, Bevilacqua MA, Baudi F, Colantuoni V, Cimino F, Venuta S, Avvedimento VE, Costanzo F. An alternative model of H ferritin promoter transactivation by c-Jun.
Biochem J 2002;
363:53-8. [PMID:
11903046 PMCID:
PMC1222450 DOI:
10.1042/0264-6021:3630053]
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Abstract
c-Jun is a member of the activator protein 1 family, and its interaction with different nuclear factors generates a wide spectrum of complexes that regulate transcription of different promoters. H ferritin promoter transcription is tightly dependent on nuclear factor Y (NFY). Ferritin transcription is activated by c-Jun, although the promoter does not contain a canonical binding site. NFY, on the other hand, does not bind c-Jun in vitro, whereas in vivo c-Jun is found in the complex containing NFY. Moreover, a c-Jun-GCN4 chimaeric construct containing only the transactivation domain of Jun and the basic-region leucine-zipper domain of GCN4 stimulates the H ferritin promoter. A synthetic GAL4 promoter and the cognate activator, the fusion protein NFY-GAL4, are potently activated by c-Jun. Titration of p300 by co-expressing E1A abolishes the stimulatory effect. Moreover, another p300-dependent promoter, the cAMP-response element, can be superactivated by c-Jun using the same mechanism. These data indicate that c-Jun, when activated or overexpressed, is recruited to the H ferritin promoter by p300, which links NFY, bound to DNA, to the complex. These results add a new level of complexity to transcriptional regulation by c-Jun, which can activate p300-dependent promoters without binding directly to the target DNA.
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