Ppm1b negatively regulates necroptosis through dephosphorylating ​Rip3

Source: Hits: 110 Pubdate: 2015-03-11

 

Abstract: The auto-phosphorylation of murine ​receptor-interacting protein 3 (​Rip3) on Thr 231 and Ser 232 in the necrosome is required to trigger necroptosis. However, how ​Rip3 phosphorylation is regulated is still largely unknown. Here we identified ​protein phosphatase 1B (​Ppm1b) as a ​Rip3 phosphatase and found that ​Ppm1b restricts necroptosis in two settings: spontaneous necroptosis caused by ​Rip3 auto-phosphorylation in resting cells, and ​tumour necrosis factor-α (​TNF)-induced necroptosis in cultured cells. We revealed that ​Ppm1b selectively suppresses necroptosis through the dephosphorylation of ​Rip3, which then prevents the recruitment of ​mixed lineage kinase domain-like protein (​Mlkl) to the necrosome. We further showed that ​Ppm1b deficiency (​Ppm1bd/d) in mice enhanced ​TNF-induced death in a ​Rip3-dependent manner, and the role of ​Ppm1b in inhibiting necroptosis was evidenced by elevated ​Rip3 phosphorylation and tissue damage in the caecum of ​TNF-treated ​Ppm1bd/d mice. These data indicate that ​Ppm1b negatively regulates necroptosis through dephosphorylating ​Rip3 in vitro and in vivo.