Role of HMGB1 in TNF-α Combined with Z-VAD-fmk-Induced L929 Cells Necroptosis

The present study established a necroptosis model in vitro and investigated the role of HMGB1 in cell necroptosis. A combination of tumor necrosis factor-alpha and z-VAD-fmk was used to induce necroptosis in L929 cells with necroptosis inhibitor necrostatin-1 applied as an intervention. Flow cytometry and transmission electron microscopy (TEM) were used to measure cell necroptosis. Western blotting assay was applied to detect the expression of receptor-interacting serine/threonine-protein kinase 3 (RIPK3), mixed lineage kinase domain-like pseudokinase (MLKL) and HMGB1. Co-immunoprecipitation (Co-IP) assay was used to confirm the interaction between HMGB1 and RIPK3. Our study demonstrated that HMGB1 migrated from the nucleus to the cytoplasm at the onset of necroptosis and was subsequently released passively to the extracellular matrix. Further experiments determined that the binding of HMGB1 with RIPK3 in the cytoplasm was loose during necroptosis. By contrast, when necroptosis was inhibited, the interaction in the cytoplasm was tight suggesting that this association between HMGB1 and RIPK3 might affect its occurrence. In conclusion, the transfer of HMGB1 from nucleus to cytoplasm, and its interaction with RIPK3 might be potentially involved in necroptosis.