Salicylic acid influences the protease activity and posttranslation modifications of the secreted peptides in the moss Physcomitrella patens

Plant secretome comprises dozens of secreted proteins. However, little is known about the composition of the whole secreted peptide pools and the proteases responsible for the generation of the peptide pools. The majority of studies focus on target detection and characterization of specific plant peptide hormones. In this study, we performed a comprehensive analysis of the whole extracellular peptidome, using moss Physcomitrella patens as a model. Hundreds of modified and unmodified endogenous peptides that originated from functional and nonfunctional protein precursors were identified. The plant proteases responsible for shaping the pool of endogenous peptides were predicted. Salicylic acid (SA) influenced peptide production in the secretome. The proteasome activity was altered upon SA treatment, thereby influencing the composition of the peptide pools. These results shed more light on the role of proteases and posttranslational modification in the “active management” of the extracellular peptide pool in response to stress conditions. It also identifies a list of potential peptide hormones in the moss secretome for further analysis.     

自噬抑制剂3-MA上调H2O2损伤的PC12细胞氧化应激水平

为探究自噬抑制剂6-氨基-3-甲基腺嘌呤（3-methyladenine,3-MA）对损伤细胞氧化应激水平的影响,将3-MA作用于H2O2诱导的PC12细胞损伤模型,以自噬增强剂雷帕霉素（rapamycin,Rap）作为对照,探讨自噬与氧化应激的关系。测定线粒体的膜电位和细胞内的活性氧（reactive oxygen species, ROS）与丙二醛(malondialdehyde, MDA)含量,以及超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活性,评价损伤细胞的氧化应激状态。单丹(磺)酰戊二胺（monodansylcadaverine,MDC）染色,观察损伤细胞的自噬情况。蛋白质印迹分析损伤细胞中的自噬相关蛋白质LC3-II/LC3-I比值变化。实验结果显示：与正常组相比,H2O2损伤细胞的ROS水平上升到正常组的141%,MDA含量增加(P<0.001);CAT与SOD酶活力显著降低(P<0.001),差异均有统计学意义,证明损伤细胞氧化应激水平增加;MDC染色结果表明,H2O2组自噬明显增加。Western印迹结果表明,LC3-II/LC3-I值显著升高（P<0.05）;与损伤组相比,3-MA组MDC染色结果表明,自噬水平降低。Western印迹结果表明,LC3-II/LC3-I值下降;细胞内ROS水平升高,增加到正常组的208%。MDA含量增加(P<0.001),CAT、SOD酶活力降低(P<0.001)。综上结果表明,自噬抑制剂可增加H2O2诱导的PC12细胞损伤模型的氧化应激水平,增加细胞凋亡。     

Of 11 candidate steroids,corticosterone concentration standardized for mass is the most reliable steroid biomarker of nutritional stress across different feather types

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