15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) protects neurons from oxidative death via an Nrf2 astrocyte-specific mechanism independent of PPARγ

Authors

  • Renée E. Haskew-Layton,

    Corresponding author
    • The Burke Medical Research Institute, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, White Plains, New York, USA
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  • Jimmy B. Payappilly,

    1. The Burke Medical Research Institute, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, White Plains, New York, USA
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  • Hongbin Xu,

    1. Neural Regeneration Laboratory and Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Canada
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  • Steffany A. L. Bennett,

    1. Neural Regeneration Laboratory and Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Canada
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  • Rajiv R. Ratan

    Corresponding author
    • The Burke Medical Research Institute, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, White Plains, New York, USA
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Address correspondence and reprint requests to Rajiv R. Ratan or Renée E. Haskew-Layton, Burke Medical Research Institute, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, 785 Mamaroneck Ave, White Plains, NY 10605, USA. E-mails: rrr2001@med.cornell.edu, rratan@burke.org, haskewlayton@yahoo.com, rhaskewlayton@pace.edu

Abstract

Astrocytes are critical for the antioxidant support of neurons. Recently, we demonstrated that low level hydrogen peroxide (H2O2) facilitates astrocyte-dependent neuroprotection independent of the antioxidant transcription factor Nrf2, leaving the identity of the endogenous astrocytic Nrf2 activator to question. In this study, we show that an endogenous electrophile, 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), non-cell autonomously protects neurons from death induced by depletion of the major antioxidant glutathione. Nrf2 knockdown in astrocytes abrogated 15d-PGJ2's neuroprotective effect as well as 15d-PGJ2 facilitated Nrf2-target gene induction. In contrast, knockdown of the transcription factor peroxisome proliferator activated-receptor gamma (PPARγ), a well-characterized 15d-PGJ2 target, did not alter 15d-PGJ2 non-cell autonomous neuroprotection. In addition, several PPARγ agonists of the thiazolidinedione (TZD) family failed to induce neuroprotection. Unexpectedly, however, the TZD troglitazone (which contains a chromanol moiety found on vitamin E) induced astrocyte-mediated neuroprotection, an effect which was mimicked by the vitamin E analogs alpha-tocopherol or alpha-tocotrienol. Our findings lead to two important conclusions: (i) 15d-PGJ2 induces astrocyte-mediated neuroprotection via an Nrf2 but not PPARγ mediated pathway, suggesting that 15d-PGJ2 is a candidate endogenous modulator of Nrf2 protective pathways in astrocytes; (ii) selective astrocyte treatment with analogs or compounds containing the chromanol moiety of vitamin E facilitates non-cell autonomous neuroprotection.

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