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On-off system for PI3-kinase-Akt signaling through S-nitrosylation of phosphatase with sequence homology to tensin (PTEN)
- Numajiri, Naoki, Takasawa, Kumi, Nishiya, Tadashi, Tanaka, Hirotaka, Ohno, Kazuki, Hayakawa, Wataru, Asada, Mariko, Matsuda, Hiromi, Azumi, Kaoru, Kamata, Hideaki, Nakamura, Tomohiro, Hara, Hideaki, Minami, Masabumi, Lipton, Stuart A., Uehara, Takashi
- Proceedings of the National Academy of Sciences of the United States of America 2011 v.108 no.25 pp. 10349-10354
- brain, cell viability, cysteine, enzyme activity, mice, nitric oxide, proteins, screening, sequence homology, support systems
- Nitric oxide (NO) physiologically regulates numerous cellular responses through S-nitrosylation of protein cysteine residues. We performed antibody-array screening in conjunction with biotin-switch assays to look for S-nitrosylated proteins. Using this combination of techniques, we found that phosphatase with sequence homology to tensin (PTEN) is selectively S-nitrosylated by low concentrations of NO at a specific cysteine residue (Cys-83). S-nitrosylation of PTEN (forming SNO-PTEN) inhibits enzymatic activity and consequently stimulates the downstream Akt cascade, indicating that Cys-83 is a critical site for redox regulation of PTEN function. In ischemic mouse brain, we observed SNO-PTEN in the core and penumbra regions but found SNO-Akt, which is known to inhibit Akt activity, only in the ischemic core. These findings suggest that low concentrations of NO, as found in the penumbra, preferentially S-nitrosylate PTEN, whereas higher concentrations of NO, known to exist in the ischemic core, also S-nitrosylate Akt. In the penumbra, inhibition of PTEN (but not Akt) activity by S-nitrosylation would be expected to contribute to cell survival by means of enhanced Akt signaling. In contrast, in the ischemic core, SNO-Akt formation would inhibit this neuroprotective pathway. In vitro model systems support this notion. Thus, we identify unique sites of PTEN and Akt regulation by means of S-nitrosylation, resulting in an "on-off" pattern of control of Akt signaling.