Discovery of a novel nucleoside immune signaling molecule 2'-deoxyguanosine in microbes and plants.

INTRODUCTION: Beneficial microorganisms play essential roles in plant growth and induced systemic resistance (ISR) by releasing signaling molecules. Our previous study obtained the crude extract from beneficial endophyte Paecilomyces variotii, termed ZNC (ZhiNengCong), which significantly enhanced plant resistance to pathogen even at 100 ng/ml. However, the immunoreactive components of ZNC remain unclear. Here, we further identified one of the immunoreactive components of ZNC is a nucleoside 2'-deoxyguanosine (2-dG). OBJECTIVES: This paper intends to reveal the molecular mechanism of microbial-derived 2'-deoxyguanosine (2-dG) in activating plant immunity, and the role of plant-derived 2-dG in plant immunity. METHODS: The components of ZNC were separated using a high-performance liquid chromatography (HPLC), and 2-dG is identified using a HPLC-mass spectrometry system (LC-MS). Transcriptome analysis and genetic experiments were used to reveal the immune signaling pathway dependent on 2-dG activation of plant immunity. RESULTS: This study identified 2'-deoxyguanosine (2-dG) as one of the immunoreactive components from ZNC. And 2-dG significantly enhanced plant pathogen resistance even at 10 ng/ml (37.42 nM). Furthermore, 2-dG-induced resistance depends on NPR1, pattern-recognition receptors/coreceptors, ATP receptor P2K1 (DORN1), ethylene signaling but not salicylic acid accumulation. In addition, we identified Arabidopsis VENOSA4 (VEN4) was involved in 2-dG biosynthesis and could convert dGTP to 2-dG, and vne4 mutant plants were more susceptible to pathogens. CONCLUSION: In summary, microbial-derived 2-dG may act as a novel immune signaling molecule involved in plant-microorganism interactions, and VEN4 is 2-dG biosynthesis gene and plays a key role in plant immunity.

Glutathione and neodiosmin feedback sustain plant immunity.

Plants have evolved a two-layer immune system comprising pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) that is activated in response to pathogen invasion. Microbial patterns and pathogen effectors can be recognized by surface-localized pattern-recognition receptors (PRRs) and intracellularly localized nucleotide-binding leucine-rich repeat receptors (NLRs) to trigger PTI and ETI responses, respectively. At present, the metabolites activated by PTI and ETI and their roles and signalling pathways in plant immunity are not well understood. In this study, metabolomic analysis showed that ETI and PTI induced various flavonoids and amino acids and their derivatives in plants. Interestingly, both glutathione and neodiosmin content were specifically up-regulated by ETI and PTI, respectively, which significantly enhanced plant immunity. Further studies showed that glutathione and neodiosmin failed to induce a plant immune response in which PRRs/co-receptors were mutated. In addition, glutathione-reduced mutant gsh1 analysis showed that GSH1 is also required for PTI and ETI. Finally, we propose a model in which glutathione and neodiosmin are considered signature metabolites induced in the process of ETI and PTI activation in plants and further continuous enhancement of plant immunity in which PRRs/co-receptors are needed. This model is beneficial for an in-depth understanding of the closed-loop mode of the positive feedback regulation of PTI and ETI signals at the metabolic level.

Development and validation of mathematical nomogram for predicting the risk of poor sleep quality among medical students.

Background: Despite the increasing prevalence of poor sleep quality among medical students, only few studies have identified the factors associated with it sing methods from epidemiological surveys. Predicting poor sleep quality is critical for ensuring medical Students' good physical and mental health. The aim of this study was to develop a comprehensive visual predictive nomogram for predicting the risk of poor sleep quality in medical students. Methods: We investigated medical Students' association with poor sleep quality at JiTang College of North China University of Science and Technology through a cross-sectional study. A total of 5,140 medical students were randomized into a training cohort (75%) and a validation cohort (25%). Univariate and multivariate logistic regression models were used to explore the factors associated with poor sleep quality. A nomogram was constructed to predict the individual risk of poor sleep quality among the medical students studied. Results: 31.9% of medical students in the study reported poor sleep quality. We performed multivariate logistic analysis and obtained the final model, which confirmed the risk and protective factors of poor sleep quality (p < 0.05). Protective factors included the absence of physical discomfort (OR = 0.638, 95% CI: 0.546-0.745). Risk factors included current drinking (OR = 0.638, 95% CI: 0.546∼0.745), heavy study stress (OR = 2.753, 95% CI: 1.456∼5.631), very heavy study stress (OR = 3.182, 95% CI: 1.606∼6.760), depressive symptoms (OR = 4.305, 95% CI: 3.581∼5.180), and anxiety symptoms (OR = 1.808, 95% CI: 1.497∼2.183). The area under the ROC curve for the training set is 0.776 and the area under the ROC curve for the validation set is 0.770, which indicates that our model has good stability and prediction accuracy. Decision curve analysis and calibration curves demonstrate the clinical usefulness of the predictive nomograms. Conclusion: Our nomogram helps predict the risk of poor sleep quality among medical students. The nomogram used includes the five factors of drinking, study stress, recent physical discomfort, depressive symptoms, and anxiety symptoms. The model has good performance and can be used for further research on and the management of the sleep quality of medical students.

Multiple forms of vitamin B6 regulate salt tolerance by balancing ROS and abscisic acid levels in maize root.

Salt stress causes osmotic stress, ion toxicity and oxidative stress, inducing the accumulation of abscisic acid (ABA) and excessive reactive oxygen species (ROS) production, which further damage cell structure and inhibit the development of roots in plants. Previous study showed that vitamin B6 (VB6) plays a role in plant responses to salt stress, however, the regulatory relationship between ROS, VB6 and ABA under salt stress remains unclear yet in plants. In our study, we found that salt stress-induced ABA accumulation requires ROS production, in addition, salt stress also promoted VB6 (including pyridoxamine (PM), pyridoxal (PL), pyridoxine (PN), and pyridoxal 5'-phosphate (PLP)) accumulation, which involved in ROS scavenging and ABA biosynthesis. Furthermore, VB6-deficient maize mutant small kernel2 (smk2) heterozygous is more susceptible to salt stress, and which failed to scavenge excessive ROS effectively or induce ABA accumulation in maize root under salt stress, interestingly, which can be restored by exogenous PN and PLP, respectively. According to these results, we proposed that PN and PLP play an essential role in balancing ROS and ABA levels under salt stress, respectively, it laid a foundation for VB6 to be better applied in crop salt resistance than ABA.

The protective effect of glycyrrhizin on hepatic ischemia-reperfusion injury in rats and possible related signal pathway.

OBJECTIVES: To investigate the protective effect of glycyrrhizin (GL) on hepatic ischemia-reperfusion injury (HIRI). MATERIALS AND METHODS: Forty SD rats were randomly divided into sham group, HIRI group, GL 100 mg/kg group, and GL 200 mg/kg group. The pathological alterations of liver tissue in each group were observed. The levels of alanine transaminase (ALT), aspartate aminotransferase (AST), endothelin-1 (ET-l), nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) were detected. Western blot was used to detect the expression levels of cytoplasmic protein caspase-3, Bax, Bcl-2, heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear protein Nrf2. RESULTS: Compared with the HIRI group, the levels of AST, ALT, ET-1, TNF-α, IL-1ß, and IL-6 in GL groups were lower, serum NO content was higher, MDA content was lower, SOD and GSH-Px activities were significantly increased, apoptosis index was lower (P<0.05), which was more obvious in high-dose GL (200 mg/kg) group. The LC3-II/LC3-I ratio and Beclin-1 protein expression levels in the GL group were significantly lower than the HIRI group, but the expression levels of cytoplasmic protein HO-1 and nuclear protein Nrf2 were significantly higher than those of the HIRI group, which was more obvious in the high-dose GL group (P<0.05). CONCLUSION: GL has a protective effect on the liver of HIRI rats, and its mechanism may be related to activation of the Nrf2/HO-1 signaling pathway, inhibition of oxidative stress, inflammation, autophagy, and apoptosis.

Expression of lncRNA MSC-AS1 in hepatocellular carcinoma cell lines and its effect on proliferation, apoptosis, and migration.

BACKGROUND/AIMS: This study aimed to explore the expression of long non-coding RNA MSC-AS1 in hepatocellular carcinoma (HCC) cells and its effect on the proliferation, migration, and apoptosis of HCC cells. MATERIALS AND METHODS: The expression of MSC-AS1 in HCC cell lines BEL7402, SMMC7721, Huh7, HepG2, MHCC97-H, and normal hepatocyte line L02 was detected by reverse transcriptase polymerase chain reaction. The HCC cells were divided into blank, negative control (NC)-small interfering RNA (siRNA) (transfected with negative siRNA), and MSC-AS1 siRNA (transfected with MSC-AS1 siRNA) groups. Cell counting kit-8 and colony formation assays were used to determine the proliferation, and cell apoptosis, migration, and invasion were detected by flow cytometry, wound healing, and transwell assays, respectively. Western blot was used to detect the expression of related proteins. RESULTS: The expression of MSC-AS1 in HCC cell lines was significantly higher than that in L02. In the MSC-AS1 siRNA group, the proliferation and colony formation of HCC cells were inhibited, whereas the apoptosis rate was significantly higher than that in the blank and NC-siRNA groups. The rate of wound healing and the number of invasion cells in the MSC-AS1 siRNA group were significantly lower than that in the blank and NC-siRNA groups. CONCLUSION: MSC-AS1 was upregulated in HCC cells, and the downregulation of MSC-AS1 could inhibit cell proliferation, migration, and invasion and promote apoptosis of HCC cells.