Accumulation of the SET protein in HEK293T cells and mild oxidative stress: cell survival or death signaling

作者：Leopoldino Andreia M^*; Squarize Cristiane H; Garcia Cristiana B; Almeida Luciana O; Pestana Cezar R; Polizello Ana C M; Uyemura Sergio A; Tajara Eloiza H; Gutkind J Silvio; Curti Carlos

来源：Molecular and Cellular Biochemistry, 2012, 363(1-2): 65-74.

DOI：10.1007/s11010-011-1158-x

• SET
• I2PP2A
• Oxidative stress
• Cell death
• Akt phosphorylation
• PTEN phosphorylation

SET protein (I2PP2A) is an inhibitor of PP2A, which regulates the phosphorylated Akt (protein kinase B) levels. We assessed the effects of SET overexpression in HEK293T cells, both in the presence and the absence of mild oxidative stress induced by 50 mu M tert-butyl hydroperoxide. Immunoblotting assays demonstrated that SET accumulated in HEK293T cells and increased the levels of phosphorylated Akt and PTEN; in addition, SET decreased glutathione antioxidant defense of cell and increased expression of genes encoding antioxidant defense proteins. Immunofluorescence analysis demonstrated that accumulated SET was equally distributed in cytoplasm and nucleus; however, in cells that had been exposed to oxidative stress, SET was found in large aggregates in the cytoplasm. SET accumulation in HEK293T cells correlated with inhibition of basal apoptosis as evidenced by a decrease in annexin V staining and activity of caspases; under mild oxidative stress, SET accumulation correlated with caspase-independent cell death, as evidenced by increased PI and annexin V/PI double staining. The results suggest that accumulated SET could act via Akt/PTEN either as cell survival signal or as oxidative stress sensor for cell death.

• 出版日期2012-4