Centre de Recherche des Cordeliers, Paris, France.
EMBO J. 2010 May 5;29(9):1585-99. doi: 10.1038/emboj.2010.43. Epub 2010 Apr 1.
Programmed necrosis induced by DNA alkylating agents, such as MNNG, is a caspase-independent mode of cell death mediated by apoptosis-inducing factor (AIF). After poly(ADP-ribose) polymerase 1, calpain, and Bax activation, AIF moves from the mitochondria to the nucleus where it induces chromatinolysis and cell death. The mechanisms underlying the nuclear action of AIF are, however, largely unknown. We show here that, through its C-terminal proline-rich binding domain (PBD, residues 543-559), AIF associates in the nucleus with histone H2AX. This interaction regulates chromatinolysis and programmed necrosis by generating an active DNA-degrading complex with cyclophilin A (CypA). Deletion or directed mutagenesis in the AIF C-terminal PBD abolishes AIF/H2AX interaction and AIF-mediated chromatinolysis. H2AX genetic ablation or CypA downregulation confers resistance to programmed necrosis. AIF fails to induce chromatinolysis in H2AX or CypA-deficient nuclei. We also establish that H2AX is phosphorylated at Ser139 after MNNG treatment and that this phosphorylation is critical for caspase-independent programmed necrosis. Overall, our data shed new light in the mechanisms regulating programmed necrosis, elucidate a key nuclear partner of AIF, and uncover an AIF apoptogenic motif.
DNA 烷化剂（如 MNNG）诱导的程序性细胞坏死是一种不依赖半胱天冬酶的细胞死亡模式，由凋亡诱导因子（AIF）介导。在多聚（ADP-核糖）聚合酶 1、钙蛋白酶和 Bax 激活后，AIF 从线粒体转移到细胞核，在细胞核中诱导染色质溶解和细胞死亡。然而，AIF 核内作用的机制在很大程度上尚不清楚。我们在这里表明，通过其 C 端脯氨酸丰富结合域（PBD，残基 543-559），AIF 在核内与组蛋白 H2AX 结合。这种相互作用通过与亲环蛋白 A（CypA）生成活性 DNA 降解复合物来调节染色质溶解和程序性细胞坏死。AIF C 端 PBD 的缺失或定向突变会破坏 AIF/H2AX 相互作用和 AIF 介导的染色质溶解。AIF 缺失或 CypA 下调会导致对程序性细胞坏死的抗性。AIF 无法在缺乏 H2AX 或 CypA 的核中诱导染色质溶解。我们还确定，在 MNNG 处理后，H2AX 在 Ser139 处发生磷酸化，并且这种磷酸化对于不依赖半胱天冬酶的程序性细胞坏死至关重要。总体而言，我们的数据为调节程序性细胞坏死的机制提供了新的认识，阐明了 AIF 的关键核内伴侣，并揭示了 AIF 的促凋亡基序。
