OBJECTIVE To explore the improvement effect and mechanism of vitexin on asthmatic model mice based on Notch signaling pathway. METHODS Asthma model of mice was established by intraperitoneal injection of ovalbumin and aluminum hydroxide suspension and nebulization stimulation of ovalbumin， and randomly divided into model group， vitexin group （40 mg/kg）， Notch activator group （1 mg/kg Jagged1）， vitexin+Notch activator group （40 mg/kg vitexin+1 mg/kg Jagged1）， with 12 mice in each group. Another 12 mice were selected as the control group. Each group received intragastric/intraperitoneal injection of relevant medicine or normal saline， once a day， for consecutive 14 days. After the last medication， minute ventilation at rest （VE） and peak expiratory flow （PEF） were detected in mice； the pathological morphology of lung tissue and fibrosis degeneration were observed and determined. The proportion of T helper cell 17 （Th17） and T regulatory cell （Treg） in peripheral blood were detected， and the Th17/Treg ratio was calculated. The levels of serum inflammatory factors interleukin （IL）-18， IL-6， IL-17 and IL-10 were determined， and the expressions of Notch1， Delta-like ligand 4 （DLL4）， hairy and enhancer of split 1 （Hes1） in lung tissue were detected. RESULTS Compared with the control group， serious pathological injury and inflammatory cell infiltration occurred in the lung tissue of mice in the model group， while VE， PEF， the proportion of Treg cells in peripheral blood and serum level of IL-10 were significantly reduced （P＜0.05）； collagen volume fraction （CVF） in lung tissue， Th17 cells proportion and Th17/Treg ratio in peripheral blood， serum levels of IL-18， IL-6 and IL-17， and the protein expressions of Notch1， DLL4 and Hes1 in lung tissue were significantly increased （P＜0.05）. Compared with the model group， the pathological injury of lung tissue in vitexin group was significantly improved compared with model group， and the changing trend of the above indexes was reversed （P＜0.05）； Notch activator Jagged1 could significantly reverse the pharmacological effects of vitexin on asthmatic mice （P＜0.05）. CONCLUSIONS Vitexin can improve lung function， Th17/Treg immune imbalance and inflammatory response， and alleviate pathological injury and fibrosis of lung tissue in asthmatic mice by inhibiting the Notch signaling pathway.

Protein lysine methylation is a prevalent post-translational modification (PTM) and plays critical roles in all domains of life. However, its extent and function in photosynthetic organisms are still largely unknown. Cyanobacteria are a large group of prokaryotes that carry out oxygenic photosynthesis and are applied extensively in studies of photosynthetic mechanisms and environmental adaptation. Here we integrated propionylation of monomethylated proteins, enrichment of the modified peptides, and mass spectrometry (MS) analysis to identify monomethylated proteins in Synechocystis sp. PCC 6803 (Synechocystis). Overall, we identified 376 monomethylation sites in 270 proteins, with numerous monomethylated proteins participating in photosynthesis and carbon metabolism. We subsequently demonstrated that CpcM, a previously identified asparagine methyltransferase in Synechocystis, could catalyze lysine monomethylation of the potential aspartate aminotransferase Sll0480 both in vivo and in vitro and regulate the enzyme activity of Sll0480. The loss of CpcM led to decreases in the maximum quantum yield in primary photosystem II (PSII) and the efficiency of energy transfer during the photosynthetic reaction in Synechocystis. We report the first lysine monomethylome in a photosynthetic organism and present a critical database for functional analyses of monomethylation in cyanobacteria. The large number of monomethylated proteins and the identification of CpcM as the lysine methyltransferase in cyanobacteria suggest that reversible methylation may influence the metabolic process and photosynthesis in both cyanobacteria and plants.
Bacterial Proteins/metabolism* ; Lysine/metabolism* ; Methyltransferases/metabolism* ; Photosynthesis ; Protein Processing, Post-Translational ; Synechocystis/growth & development*