Role of CREB on heme oxygenase-1 induction in adrenal cells: involvement of the PI3K pathway

ASTORT F; REPETTO EM; ROCHA VIEGAS L; MERCAU ME; SANCHEZ PUCH S; FINKIELSTEIN CV; PECCI A; CYMERYNG CB

JOURNAL OF MOLECULAR ENDOCRINOLOGY

BIOSCIENTIFICA LTD

Lugar: Bristol; Año: 2016 vol. 57 p. 113 - 124

0952-5041

In addition to the well-known function of ACTH as the main regulator of adrenalsteroidogenesis, we have previously demonstrated its effect on the transcriptionalstimulation of HO-1 expression, a component of the cellular antioxidant defense system.In agreement, we hereby demonstrate that, in adrenocortical Y1 cells, HO-1 inductioncorrelates with a signi cant prevention of the generation of reactive oxygen speciesinduced by H2O2/Fe2+. ACTH/cAMP-dependent activation of redox-imbalanced relatedfactors such as NRF2 or NFκB and the participation of MAPKs in this mechanism was,however, discarded based on results with speci c inhibitors and reporter plasmids. Wesuggest the involvement of CREB in HO-1 induction by ACTH/cAMP, as transfection of cells with a dominant-negative isoform of CREB (DN-CREB-M1) decreased, whileoverexpression of CREB increased HO-1 protein levels. Sequence screening of the murineHO-1 promoter revealed CRE-like sites located at −146 and −37 of the transcription startsite and ChIP studies indicated that this region recruits phosphorylated CREB (pCREB)upon cAMP stimulation in Y1 cells. In agreement, H89 (PKA inhibitor) or cotransfectionwith DN-CREB-M1 prevented the 8Br-cAMP-dependent increase in luciferase activity in cells transfected with pHO-1[−295/+74].LUC. ACTH and cAMP treatment induced the activation of the PI3K/Akt signaling pathway in a PKA-independent mechanism.Inhibition of this pathway prevented the cAMP-dependent increase in HO-1 protein levelsand luciferase activity in cells transfected with pHO-1[−295/+74].LUC. Finally, here weshow a crosstalk between the cAMP/PKA and PI3K pathways that affects the binding ofp-CREB to its cognate element in the murine promoter of the Hmox1 gene.