Reversible inactivation of the tumor suppressor PTEN by H2O2.
The tumor suppressor PTEN regulates cell migration, growth, and survival by removing the 3'-phosphate of phosphoinositides. Exposure of purified PTEN or of cells to H(2)O(2) resulted in inactivation of PTEN in a time- and H(2)O(2) concentration-dependent manner. Analysis of various cysteine mutants, including mass spectrometry of tryptic peptides, indicated that the essential Cys(124) residue in the active site of PTEN specifically forms a disulfide with Cys(71) during oxidation by H(2)O(2). The reduction of H(2)O(2)-oxidized PTEN in cells appears to be mediated predominantly by thioredoxin. Thus, thioredoxin was more efficient than glutaredoxin, glutathione, or a 14-kDa thioredoxin-like protein with regard to the reduction of oxidized PTEN in vitro. Thioredoxin co-immunoprecipitated with PTEN from cell lysates; and incubation of cells with 2,4-dinitro-1-chlorobenzene (an inhibitor of thioredoxin reductase) delayed the reduction of oxidized PTEN, whereas incubation with buthioninesulfoximine (an inhibitor of glutathione biosynthesis) did not. These results suggest that the reversible inactivation of PTEN by H(2)O(2) might be important for the accumulation of 3'-phosphorylated phosphoinositides and that the uncontrolled generation of H(2)O(2) associated with certain pathological conditions might contribute to cell proliferation by inhibiting PTEN function.
Lee
Seung-Rock
SR
Laboratory of Cell Signaling, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-8015, USA. sgrhee@nih.gov
Yang
Kap-Seok
KS
Kwon
Jaeyul
J
Lee
Chunghee
C
Jeong
Woojin
W
Rhee
Sue Goo
SG
D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors*
D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; D006861:Hydrogen Peroxide; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human