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Necroptosis is a form of regulated cell death that depends on the receptor-interacting serine-threonine kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL). The molecular mechanisms underlying distinct instances of necroptosis have only recently begun to emerge. In the present study, we characterized RABGEF1 as a positive regulator of RIPK1/RIPK3 activation in vitro. Based on the overexpression and knockdown experiments, we determined that RABGEF1 accelerated the phosphorylation of RIPK1 and promoted necrosome formation in L929 cells. The pro-necrotic effect of RABGEF1 is associated with its E3 ubiquitin ligase activity and guanine nucleotide exchange factor (GEF) activity. We further confirmed that RABGEF1 interacts with cIAP1 protein by inhibiting its function and plays a regulatory role in necroptosis, which can be abolished by treatment with the antagonist Smac mimetic (SM)-164. In conclusion, our study highlights a potential and novel role of RABGEF1 in promoting TNF-induced cell necrosis., Competing Interests: Declaration of competing interest No conflict of interest exits in the submission of this manuscript. All authors listed have approved the manuscript that is enclosed and declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Necroptosis is a form of regulated cell death that has been implicated in multiple diseases. TNF-induced necroptosis is regulated by necrosomes, complexes consisting of RIPK1, RIPK3 and MLKL. In this study, by screening of a small-compound library, we identified dozens of compounds that inhibited TNF-induced necroptosis. According to the mechanisms by which they inhibited necroptosis, these compounds were classified into different groups. We then identified Ibrutinib as an inhibitor of RIPK3 and found that Quizartinib protected against the TNF-induced systemic inflammatory response syndrome in mice by inhibiting the activation of RIPK1. Altogether, our work revealed dozens of necroptosis inhibitors, suggesting new potential approaches for treating necroptosis-related diseases., (© 2023. Springer Nature Limited.)

Mixed lineage kinase domain-like protein (MLKL) is identified as the terminal executor of necroptosis. However, its role in acute alcoholic liver injury remains unclear. This study elucidates that MLKL can contribute to acute alcoholic liver injury independently of necroptosis. Although the expression of MLKL was upregulated, no significant increase in its phosphorylation or membrane translocation was observed in the liver tissues of mice treated with ethanol. This finding confirms that alcohol intake does not induce necroptosis in mouse liver tissue. Additionally, the deletion of Mlkl resulted in the downregulation of NLRP3 expression, which subsequently inhibited the activation of the NLRP3 inflammasome and the ensuing inflammatory response, thereby effectively mitigating liver injury induced by acute alcohol consumption. The knockout of Nlrp3 did not affect the expression of MLKL, further confirming that MLKL acts upstream of NLRP3. Mechanistically, inhibiting the nuclear translocation of MLKL reduced the nuclear entry of p65, the principal transcriptional regulator of NLRP3, thereby limiting the transcription of Nlrp3 mRNA and subsequent NLRP3 expression. Overall, this study unveils a novel mechanism of MLKL regulates the activation of NLRP3 inflammasomes in a necroptosis independent way in acute alcoholic liver injury [Display omitted] • Acute alcohol increased MLKL and RIPK3 without MLKL phosphorylation/translocation. • Mlkl deficiency can alleviate acute alcoholic liver injury". • Mlkl deficiency can limit NLRP3 inflammasome activation. • Nlrp3 -/- mice were resistant to alcoholic liver injury and inflammatory responses. • Loss of MLKL limits NLRP3 by decreasing NF-κB p65's nuclear entry. [ABSTRACT FROM AUTHOR]