Cysteine protease mcll-Pa executes programmed cell death during plant embryogenesis
Cysteine protease mcll-Pa executes programmed cell death during plant embryogenesis
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DOI：
10.1073/pnas.0506948102
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发表时间：
2005-10-04
影响因子：
11.1
通讯作者：
Smertenko, A
中科院分区：
文献类型：
--
作者：
Bozhkov, PV;Suarez, MF;Smertenko, A
细胞程序性死亡（PCD）是真核生物发育过程中不可或缺的过程。在动物中，PCD由半胱氨酸蛋白酶的半胱天冬酶家族执行。植物没有半胱氨酸天冬氨酸蛋白酶的同源物，但具有称为后半胱氨酸天冬氨酸蛋白酶的半胱氨酸蛋白酶的遗传学上遥远的家族。后半胱氨酸天冬氨酸蛋白酶在PCD中的细胞功能尚不清楚。在这里，我们表明，在植物胚胎发生过程中，metacaspase mcII-Pa从细胞质易位到细胞核中的终末分化的细胞是注定要消除，在那里它与核孔复合物和染色质共定位，造成核膜解体和DNA片段化。mcII-Pa的细胞死亡功能依赖于其半胱氨酸依赖性丝氨酸特异性蛋白水解活性。因此，催化性半胱氨酸的突变消除了mcII-Pa的蛋白水解活性并阻断了核降解。这些结果确立了后半胱天冬酶作为胚胎形成过程中PCD的执行者，并提供了植物中PCD和胚胎发生之间的功能联系。虽然mcII-Pa和后生动物半胱天冬酶具有不同的底物特异性，但它们在发育过程中具有共同的功能，表明植物和动物中PCD途径的进化平行性。
Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is executed by the caspase family of cysteine proteases. Plants do not have close homologues of caspases but possess a phylogenetically distant family of cysteine proteases named metacaspases. The cellular function of metacaspases in PCD is unknown. Here we show that during plant embryogenesis, metacaspase mcII-Pa translocates from the cytoplasm to nuclei in terminally differentiated cells that are destined for elimination, where it colocalizes with the nuclear pore complex and chromatin, causing nuclear envelope disassembly and DNA fragmentation. The cell-death function of mcII-Pa relies on its cysteine-dependent arginine-specific proteolytic activity. Accordingly, mutation of catalytic cysteine abrogates the proteolytic activity of mcII-Pa and blocks nuclear degradation. These results establish metacaspase as an executioner of PCD during embryo patterning and provide a functional link between PCD and embryogenesis in plants. Although mcII-Pa and metazoan caspases have different substrate specificity, they serve a common function during development, demonstrating the evolutionary parallelism of PCD pathways in plants and animals.