TY - JOUR T1 - PTEN Inhibition by 4-Hydroxynonenal Leads to Increased Akt Activation in Hepatocytes JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.110.069534 SP - mol.110.069534 AU - Colin T. Shearn AU - Rebecca L. Smathers AU - Benjamin J. Stewart AU - Kristofer S. Fritz AU - James J. Galligan AU - Numsen Hail AU - Dennis R. Petersen Y1 - 2011/03/17 UR - http://molpharm.aspetjournals.org/content/early/2011/03/17/mol.110.069534.abstract N2 - The production of reactive aldehydes such as 4-hydroxynonenal (4-HNE) is proposed to be an important factor in the etiology of alcoholic liver disease. To understand the effects of 4-HNE on homeostatic signaling pathways in hepatocytes, cellular models consisting of the human hepatocellular carcinoma cell line (HepG2) and primary rat hepatocytes were evaluated. Treatment of both HepG2 cells and primary hepatocytes with subcytotoxic concentrations of 4-HNE resulted in the activation of Akt within 30 min as demonstrated by increased phosphorylation of residues Ser473 and Thr308. Quantification and subsequent immunocytochemistry of PtdIns (3,4,5) P3 resulted in a 6 fold increase in total PtdIns (3,4,5) P3 and increased immunostaining at the plasma membrane following 4-HNE treatment. Co-treatment of HepG2 cells with 4-HNE and the phosphatidylinositol 3-kinase inhibitor Ly294002 or the protein phosphatase 2A inhibitor okadaic acid, revealed that the mechanism of activation of Akt is PI3K-dependent and PP2A independent. Using biotin hydrazide detection, it was established that the incubation of HepG2 cells with 4-HNE resulted in increased carbonylation of the lipid phosphatase PTEN, a key regulator of Akt activation. Activity assays both in HepG2 cells and recombinant PTEN revealed a decrease in PTEN lipid phosphatase activity following 4-HNE application. Mass spectral analysis of 4-HNE treated recombinant PTEN detected a single 4-HNE adduct. Subsequent analysis of Akt dependent physiological consequences of 4-HNE in HepG2 cells revealed significant increases in the accumulation of neutral lipids. These results provide a potential mechanism of Akt activation and cellular consequences of 4-HNE in hepatocytes. ER -