congresos y reuniones científicas
CREB MEDIATES ACTH DEPENDENT HO-1 EXPRESSION IN ADRENAL CELLS: ROLE OF PI3K PATHWAY
CYMERYNG CB; MERCAU ME; REPETTO EM; VECINO C; CALDARERI L; ROCHA-VIEGAS L; PECCI A; ASTORT F
San Carlos de Bariloche
Simposio; SISTAM2015; 2015
Stimulation of adrenal steroidogenesis by ACTH has been associated with increased generation of reactive oxygen species. Accordingly, we have previously shown that induction of HO-1 by ACTH in adrenocortical cells prevent deleterious effects caused by oxidative stress. We have also demonstrated that HO-1-induction by ACTH involves transcriptional effects and activation of the cAMP/PKA pathway. In the present study we used a sequential deletion protocol to localize the promoter region of the mouse HO-1 gene involved in the induction of HO-1 by ACTH/cAMP in adrenocortical cells. Experiments performed with luciferase reporter constructs and pharmacological inhibitors of PKA (H89) or dominant negative CREB isoforms we identified a regulatory region located within the proximal promoter (-295/+74), involved in the transcriptional stimulation of HO-1. Sequence analysis indicates that this region includes two putative cAMP-responsive elements (CRE). We also demonstrate the involvement of PI3K/Akt pathway in the induction of HO-1 by ACTH/cAMP. Finally we showed that stimulation of the ACTH/cAMP pathway induces the recruitment of the phosphorylated CRE-binding protein (pCREB) to the promoter region of the endogenous HO-1 gene and demonstrated that this mechanism is also modulated by the activation of the PI3K pathway. In summary, in this study we identified a region in the proximal promoter of the HO-1 gene, containing putative CRE sites, that is involved in its transcriptional stimulation by ACTH and showed showed that both cAMP and PI3K pathways are involved in this mechanism.