Rojo, AnaSalinas, MartaSalazar Roa, MaríaTakahashi, ShigeruSuske, GuntramCalvo, VictorSagarra, María Rosa deCuadrado, Antonio2024-01-312024-01-312006Rojo, Ana I., et al. «Regulation of Heme Oxygenase-1 Gene Expression through the Phosphatidylinositol 3-Kinase/PKC-ζ Pathway and Sp1». Free Radical Biology and Medicine, vol. 41, n.o 2, julio de 2006, pp. 247-61. https://doi.org/10.1016/j.freeradbiomed.2006.04.002.0891-584910.1016/j.freeradbiomed.2006.04.002https://hdl.handle.net/20.500.14352/97400The molecular mechanisms involved in modulation of the antioxidant cell defence by survival signals remain largely unexplored. Here, we report a mechanistic connection between the survival signal elicited by nerve growth factor (NGF) and the antioxidant cell defence represented by heme oxygenase-1 (HO-1) at the level of a newly identified Sp1 site in the human ho1 proximal promoter. By using luciferase reporter constructs we identified a PI3K-responsive region containing a GC-box that resembled the response element for Sp1. Indeed, transfection of Sp1-deficient SL2 cells, electrophoretic mobility shift assays, the use of the GC-box binding drug mithramycin, and mutation of the GC-box provided evidence for a Sp1-like site in the PI3K-sensitive region. Then, we observed with the use of a Sp1–Gal4 chimera that PI3K regulates the transactivating capacity of Sp1. Cotransfection of active PI3K and PKC-ζ expression vectors resulted in substantial increase of Sp1 phosphorylation and in synergistic activation of both Sp1-Gal4 and endogenous Sp1. Moreover, these effects were mimicked by cotransfection of active MEK and ERK expression vectors and were blocked by the MEK inhibitor PD98059. Inhibition of HO-1 with Sn protoporphyrin IX and blockage of Sp-1-mediatied upregulation of HO-1 with mithramycin attenuated antioxidant and cytoprotective functions of NGF against hydrogen peroxide. This study elucidates how NGF contributes to protection of target cells against oxidative stress.engjournal article1873-4596https://doi.org/10.1016/j.freeradbiomed.2006.04.002https://www.sciencedirect.com/science/article/abs/pii/S0891584906002450?via%3Dihubrestricted accessHO1Free radicalsPhosphatidylinositol 3-kinaseBiología celular (Biología)2403 Bioquímica