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Nature Cell Biology：动物与植物细胞凋亡机制的保守性
基因狗生物论坛快讯：参与植物细胞程序性死亡（programmed cell death, PCD）的金属水解酶 （metacaspase），cystein protease 的底物一直不清楚。最新一期的 Nature Cell Biology 报道了 Bozkhov 和他同事证明在植物细胞发育和胁迫诱导性 PCD 中， metacaspase II 水解剪切一个叫 Tudor staphylococcal nuclease (TSN) 的 splicing regulator，这种水解活性和动物细胞凋亡中 caspase-3 很类似，这也从一个侧面说明了不管是动物细胞还是植物细胞在细胞凋亡一些分子机制进化上的保守性。
Nature Cell Biology
Published online: 11 October 2009 | doi:10.1038/ncb1979
Tudor staphylococcal nuclease is an evolutionarily conserved component of the programmed cell death degradome
Programmed cell death (PCD) is executed by proteases, which cleave diverse proteins thus modulating their biochemical and cellular functions. Proteases of the caspase family and hundreds of caspase substrates constitute a major part of the PCD degradome in animals1, 2. Plants lack close homologues of caspases, but instead possess an ancestral family of cysteine proteases, metacaspases3, 4. Although metacaspases are essential for PCD5, 6, 7, their natural substrates remain unknown4, 8. Here we show that metacaspase mcII-Pa cleaves a phylogenetically conserved protein, TSN (Tudor staphylococcal nuclease), during both developmental and stress-induced PCD. TSN knockdown leads to activation of ectopic cell death during reproduction, impairing plant fertility. Surprisingly, human TSN (also known as p100 or SND1), a multifunctional regulator of gene expression9, 10, 11, 12, 13, 14, 15, is cleaved by caspase-3 during apoptosis. This cleavage impairs the ability of TSN to activate mRNA splicing, inhibits its ribonuclease activity and is important for the execution of apoptosis. Our results establish TSN as the first biological substrate of metacaspase and demonstrate that despite the divergence of plants and animals from a common ancestor about one billion years ago and their use of distinct PCD pathways, both have retained a common mechanism to compromise cell viability through the cleavage of the same substrate, TSN.
http://www.nature.com/ncb/journal/vaop/ncurrent/abs/ncb1979.html |
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