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GRIM-19-mediated translocation of STAT3 to mitochondria is necessary for TNF-induced necroptosis
Nataly Shulga, John G. Pastorino


Tumor necrosis factor (TNF) can induce necroptosis, wherein inhibition of caspase activity prevents apoptosis but initiates an alternative programmed necrosis. The activity of receptor-interacting serine/threonine-protein kinase 1 (RIPK-1) is required for necroptosis to proceed, with suppression of RIPK-1 expression or inhibition of RIPK-1 activity with necrostatin-1 preventing TNF-induced necroptosis. Downstream from the TNF receptor, the generation of reactive oxygen species at the mitochondria has been identified as necessary for the execution of necroptosis; with antioxidants and inhibitors of mitochondrial complex I preventing TNF-induced cytotoxicity. However, components of the signaling pathway that lie between activated RIPK-1 and the mitochondria are unknown. In the study reported here we demonstrate that during TNF-induced necroptosis, STAT3 is phosphorylated on serine 727, which is dependent on RIPK-1 expression or activity. The phosphorylation of STAT3 induces interaction with GRIM-19, a subunit of mitochondrial complex I, with a resultant translocation of STAT3 to the mitochondria, where it induces an increase in reactive oxygen species production and cell death.


  • Accepted February 8, 2012.
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