Identification of molecular mechanism of necroptosis mediated by PI3K / 军事医学

ABSTRACT

Objective To identify the molecular mechanism of phosphatidylinositol-3-kinase (PI3K) in mediating necroptosis induced by tumor necrosis factor alpha (TNFα).Methods RNA interference mediated by lentivirus short hairpin RNA(shRNA) was used to downregulate p110α in L929 cells and Western blotting was used to determine the knockdown efficiency.In addition,Western blotting was used to detect the phosphorylation level of RIP1,RIP3 and MLKL in L929 cells treated with or without TNFα plus Z-VAD.Duolink assay kit was used to detect the interactions between different proteins or the same proteins.Results p110α knockdown was efficiently mediated by the lentivirus shRNA,which significantly suppressed the phosphorylation of RIP1,RIP3 and MLKL in the absence or presence of TNFα plus Z-VAD stimulation.Moreover,the interactions between p110α and RIP3,but not RIP1,increased in a time-dependent manner during the process of necroptosis,and p110α knockdown significantly inhibited the formation of necrosome and RIP1 homodimer or RIP3 homodimer.Conclusion PI3K mediates the TNFα-induced necroptosis by promoting the activation of RIP1/RIP3/MLKL signaling pathway.Given the increasing direct interactions between p110α and RIP3 during the process of necrosome formation,PI3K may regulate RIP3 kinase activity via direct phosphorylation of RIP3.