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MADD Is a Downstream Target of PTEN in Triggering Apoptosis

Authors

  • Shankar Jayarama,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Liang-Cheng Li,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Lakshmy Ganesh,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • David Mardi,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Prasad Kanteti,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Nissim Hay,

    1. Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Peifeng Li,

    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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  • Bellur S. Prabhakar

    Corresponding author
    1. Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
    • Correspondence to: Bellur S. Prabhakar, PhD, Professor Head, Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612.

      E-mail: bprabhak@uic.edu

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  • Authors have no conflict of interest to declare.
  • Shankar Jayarama, Liang-Cheng Li, and Lakshmy Ganesh are contributed equally to this work.

Abstract

Mitogen-activated kinase activating death domain containing protein (MADD) is abundantly expressed in cancer cells and necessary for maintaining cancer cell survival. However, this survival function of MADD is dependent upon its phosphorylation by protein kinase B (Akt). The tumour suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a lipid phosphatase that negatively regulates the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. The downstream targets of PTEN in triggering apoptosis have not yet been completely identified. Here, we report that MADD can act as a pro-apoptotic factor to initiate TRAIL-induced apoptosis when its phosphorylation is attenuated by PTEN. Our data show that tumor necrosis factor α-related apoptosis-inducing ligand (TRAIL) induced a reduction in MADD phosphorylation with a concomitant up-regulation of PTEN. Knock down of PTEN using a specific siRNA prevented TRAIL-induced reduction in pMADD levels. Surprisingly, Akt non-phopshorylated MADD translocated from the plasma membrane to cytoplasm where it bound to 14-3-3 and displaced 14-3-3 associated Bax, which translocated to mitochondria resulting in cytochrome c release. Taken together, our data reveal that PTEN can convey the death signal by preventing MADD phosphorylation by Akt. J. Cell. Biochem. 115: 261–270, 2014. © 2013 Wiley Periodicals, Inc.

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