Role of CREB on Heme Oxygenase-1 Induction in Adrenal Cells. Involvement of the PI3K Pathway

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

JOURNAL OF MOLECULAR ENDOCRINOLOGY

BIOSCIENTIFICA LTD

Lugar: Bristol; Año: 2016

0952-5041

In addition to the well known function of ACTH as the main regulator of adrenal steroidogenesis, we have previously demonstrated its effect on the transcriptional stimulation of HO-1 expression, a component of the cellular antioxidant defense system. In agreement we demonstrated that HO-1 induction correlates with a significant prevention of the generation of reactive oxygen species induced by H2O2/Fe2+28 .Activation of redox-imbalanced related factors as Nrf2, AP-1 or NFκB by ACTH/cAMP was, however, discarded based on results with specific inhibitors and reporter plasmids. We suggested the involvement of CREB in HO-1 induction by ACTH/cAMP as transfection of adrenocortical Y1 cells with a dominant negative isoform of CREB (DN-CREB-M1) decreased, while overexpression of CREB increased HO-1 protein levels. Sequence screening of the murine HO-1 promoter revealed CRE-like sites located at -146 and -37 of the TSS and ChIP studies indicated that this region of the endogenous HO-1 gene recruits phosphorylated CREB (pCREB) upon cAMP stimulation in Y1 cells. In agreement, 8Br-cAMP stimulated luciferase activity in cells transfected with pHO-1[-295/+74].LUC was downregulated by H89 (PKA inhibitor) or by co37 transfection with DN-CREB-M1. 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 levels and luciferase activity in cells transfected with pHO-1[-295/+74].LUC. Finally, here we show a crosstalk between the cAMP/PKA and PI3K pathways that affects the binding of p-CREB to its cognate element in the murine promoter of the HO-1 gene.