Programmed cell death (PCD) is crucial for development and homeostasis of all multicellular organisms. In human cells, the double role of extra‐mitochondrial cytochrome c in triggering apoptosis and inhibiting survival pathways is well reported. In plants, however, the specific role of cytochrome c upon release from the mitochondria remains in part veiled yet death stimuli do trigger cytochrome c translocation as well. Here, we identify an Arabidopsis thaliana 14‐3‐3ι isoform as a cytosolic cytochrome c target and inhibitor of caspase‐like activity. This finding establishes the 14‐3‐3ι protein as a relevant factor at the onset of plant H₂O₂‐induced PCD. The in vivo and in vitro studies herein reported reveal that the interaction between cytochrome c and 14‐3‐3ι exhibits noticeable similarities with the complex formed by their human orthologues. Further analysis of the heterologous complexes between human and plant cytochrome c with plant 14‐3‐3ι and human 14‐3‐3ε isoforms corroborated common features. These results suggest that cytochrome c blocks p14‐3‐3ι so as to inhibit caspase‐like proteases, which in turn promote cell death upon H₂O₂ treatment. Besides establishing common biochemical features between human and plant PCD, this work sheds light onto the signaling networks of plant cell death.

中文翻译：

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通过细胞色素 c 与 14-3-3 蛋白结合调节植物中 H2O2 诱导的程序性细胞死亡的拟议机制

程序性细胞死亡 (PCD) 对所有多细胞生物的发育和体内平衡至关重要。在人类细胞中，线粒体外细胞色素c在触发细胞凋亡和抑制存活途径方面的双重作用已被广泛报道。然而，在植物中，细胞色素c从线粒体释放后的特定作用仍然部分隐藏，但死亡刺激也会触发细胞色素c易位。在这里，我们将拟南芥14-3-3ι 亚型鉴定为胞质细胞色素c靶标和半胱天冬酶样活性抑制剂。这一发现将 14-3-3ι 蛋白确定为植物 H ₂ O ₂开始时的相关因素诱发的 PCD。在体内和体外本文报道的研究表明，细胞色素之间的相互作用Ç和14-3-3ι展品明显相似之处可以通过人类直系同源物形成的复合物。对人类和植物细胞色素c与植物 14-3-3ι 和人类 14-3-3ε 同种型之间的异源复合物的进一步分析证实了共同特征。这些结果表明，细胞色素c阻断 p14-3-3ι 以抑制半胱天冬酶样蛋白酶，进而促进 H ₂ O _{2 下的}细胞死亡治疗。除了在人类和植物 PCD 之间建立共同的生化特征外，这项工作还揭示了植物细胞死亡的信号网络。