Regulation of necroptosis by targeting tumor suppressor death-associated protein kinase 1

Abstract

Death-associated protein kinase 1 (DAPK1, DAPk, DAPK) is known for its involvement in apoptosis and autophagy-associated cell death. Here, we identified an unexpected function of DAPK1 in suppressing necroptosis. DAPK1-deficiency renders macrophages and dendritic cells susceptible to necroptotic induction by different stimuli. We also observed an inhibitory role for DAPK1 in necroptosis in HT-29 cells, since knockdown or knockout of DAPK1 in such cells increased their sensitivity to necroptosis. Increased necroptosis was associated with enhanced formation of the RIPK1-RIPK3-MLKL complex in these DAPK1-deficient cells. We further found that DAPK1-deficiency led to decreased MAPK activated kinase 2 (MK2) activation and reduced RIPK1 S321 phosphorylation, with this latter representing a critical step controlling necrosome formation. Most TNF signaling pathways, including ERK, JNK and AKT, were not regulated by DAPK. In contrast, DAPK selectively promoted MKK3-induced p38 MAPK activation, resulting in enhanced MK2 phosphrylation. Our results reveal a novel role for DAPK1 in inhibiting necroptosis and illustrate an unexpected selectivity for DAPK1 in promoting p38 MAPK-MK2 activation. Importantly, our study suggests that modulation of necroptosis and p38/MK2-mediated inflammation may be achieved by targeting DAPK1.