The proteasome is responsible for caspase-3-like activity during xylem development
The proteasome is responsible for caspase-3-like activity during xylem development
复制标题
蛋白酶体在木质部发育过程中负责 caspase-3 样活性
DOI：
10.1111/j.1365-313x.2012.05070.x
复制
发表时间：
2012-10-01
期刊：
影响因子：
7.2
通讯作者：
He, Xin-Qiang
中科院分区：
文献类型：
--
作者：
Han, Jia-Jia;Lin, Wei;He, Xin-Qiang
木质部发育是木质部细胞末端分化的过程，包括细胞分裂、细胞膨胀、次生壁形成和细胞程序性死亡（PCD）。植物中的PCD和动物中的细胞凋亡有许多共同的特征。Caspase-3具有Asp-Glu-Val-Asp（DEVD）特异性，是动物细胞凋亡过程中的关键刽子手。虽然在植物中不存在与caspase-3同源的基因，但caspase-3样活性参与了许多PCD和发育过程。然而，没有直接的证据表明，半胱天冬酶-3样活性存在于木质部细胞死亡。在这项研究中，我们发现，caspase-3样活性是存在的，并与次生木质部发育毛白杨。利用疏水层析、Q阴离子交换层析和凝胶过滤层析从白杨次生木质部中分离纯化了具有caspase-3样活性的蛋白酶。经液相色谱-串联质谱（LC-MS/MS）鉴定，20 S蛋白酶体（20 SP）是次生木质部发育过程中类caspase-3活性的主要来源。20 SP杨有7个α亚基，由12个基因编码，7个β亚基由12个基因编码。药理实验表明，半胱天冬酶-3抑制剂Ac-DEVD-CHO抑制拟南芥子叶的木质部分化。此外，蛋白酶体抑制剂clasto-lactacystin β-lactone抑制了VND 6诱导的拟南芥木质化培养中导管分子的PCD。总之，20 S蛋白酶体是负责caspase-3样活性，并参与木质部的发展。
Xylem development is a process of xylem cell terminal differentiation that includes initial cell division, cell expansion, secondary cell wall formation and programmed cell death (PCD). PCD in plants and apoptosis in animals share many common characteristics. Caspase-3, which displays Asp-Glu-Val-Asp (DEVD) specificity, is a crucial executioner during animal cells apoptosis. Although a gene orthologous to caspase-3 is absent in plants, caspase-3-like activity is involved in many cases of PCD and developmental processes. However, there is no direct evidence that caspase-3-like activity exists in xylem cell death. In this study, we showed that caspase-3-like activity is present and is associated with secondary xylem development in Populus tomentosa. The protease responsible for the caspase-3-like activity was purified from poplar secondary xylem using hydrophobic interaction chromatography (HIC), Q anion exchange chromatography and gel filtration chromatography. After identification by liquid chromatography-tandem mass spectrometry (LC-MS/MS), it was revealed that the 20S proteasome (20SP) was responsible for the caspase-3-like activity in secondary xylem development. In poplar 20SP, there are seven a subunits encoded by 12 genes and seven beta subunits encoded by 12 genes. Pharmacological assays showed that Ac-DEVD-CHO, a caspase-3 inhibitor, suppressed xylem differentiation in the veins of Arabidopsis cotyledons. Furthermore, clasto-lactacystin beta-lactone, a proteasome inhibitor, inhibited PCD of tracheary element in a VND6-induced Arabidopsis xylogenic culture. In conclusion, the 20S proteasome is responsible for caspase-3-like activity and is involved in xylem development.