Akt-mediated activation of HIF-1 in pulmonary vascular endothelial cells by S-nitrosoglutathione

作者：Carver D Jeannean; Gaston Benjamin; Deronde Kimberly; Palmer Lisa A^*

来源：American Journal of Respiratory Cell and Molecular Biology, 2007, 37(3): 255-263.

DOI：10.1165/rcmb.2006-0289SM

• phosphatidylinositol 3-kinase
• hypoxia-inducible factor-1
• S-nitrosothiol
• gamma-glutamyl transpeptidase
• PTEN

S-nitrosoglutathione (GSNO) stabilizes the a-subunit of hypoxia inducible factor-1 (HIF-1) in normoxic cells, but not in the presence of PI3K inhibitors. In this report, the biochemical pathway by which GSNO alters PI3K/Akt activity to modify HIF-1 expression was characterized in Cos cells and primary pulmonary vascular endothelial cells. GSNO increased Akt kinase activity-and downstream HIF-1 alpha protein accumulation and DNA-binding activity-in a dose- and time-dependent manner. The PI3K inhibitors, wortmannin and LY294002, blocked these responses. Neither glutathione nor 8-bromo-cyclic GMP mimicked the GSNO-induced increases in Akt kinase activity. GSNO-induced Akt kinase activity and downstream HIF-1 alpha stabilization were blocked by acivicin, an inhibitor of gamma-glutamyl transpeptidase (gamma GT), a transmembrane protein that can translate extracellular GSNO to intracellular S-nitrosocysteinylglycine. Dithiothreitol blocked GSNO-induced Akt kinase activity and HIF-1 alpha stabilization. Moreover, the 3'-phosphatase of phosphoinositides, PTEN (phosphatase and tensin homolog deleted on chromosome ten) was S-nitrosylated by GSNO in pulmonary arterial endothelial cells, which was reversed by dithiothreitol and ultraviolet light. Interestingly, the abundance of S-nitrosylated PTEN also correlated inversely with PTEN activity. Taken together, these results suggest that GSNO induction of Akt appears to be mediated by S-nitrosylation chemistry rather than classic NO signaling through guanylate cyclase/cG MP. We speculate that gamma GT-dependent activation of Akt and subsequent activation of HIF-1 in vascular beds may be relevant to the regulation of HIF-1-dependent gene expression in conditions associated with oxyhemoglobin deoxygenation, as opposed to profoundly low Po(2), in the pulmonary vasculature.

• 出版日期2007-9