Abstract：
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.
摘要：
坏死性凋亡是调节细胞死亡的一种形式，取决于受体相互作用的丝氨酸-苏氨酸激酶3（RIPK3）和混合谱系激酶结构域样（MLKL）。坏死的不同实例的分子机制直到最近才开始出现。在本研究中,我们将RABGEF1表征为体外RIPK1/RIPK3激活的正调节因子。基于过表达和敲低实验，我们确定RABGEF1在L929细胞中加速RIPK1的磷酸化并促进坏死体的形成。RABGEF1的促坏死作用与其E3泛素连接酶活性和鸟嘌呤核苷酸交换因子(GEF)活性相关。我们进一步证实，RABGEF1通过抑制cIAP1蛋白的功能与cIAP1蛋白相互作用，在坏死性凋亡中起调节作用，可以通过用拮抗剂Smac模拟物（SM）-164治疗来消除。总之,我们的研究强调了RABGEF1在促进TNF诱导的细胞坏死中的潜在和新的作用.
