Mitogen-activated Protein Kinase Research Articles

Chemical-sensitized MITOGEN-ACTIVATED PROTEIN KINASE 4 provides insights into its functions in plant growth and immunity

Abstract Two mitogen-activated protein kinase (MAPK) cascades with MPK4 and MPK3/MPK6 as the bottommost kinases are key to plant growth/development and immune signaling. Disruption of the MPK4 cascade leads to severe dwarfism and autoimmunity, complicating the study of MPK4 in plant growth/development and immunity. In this study, we successfully rescued the Arabidopsis (Arabidopsis thaliana) mpk4 mutant using a chemical-sensitized MPK4 variant, MPK4YG, creating a conditional activity-null mpk4 mutant named MPK4SR (genotype: PMPK4:MPK4YG mpk4) that could be used to examine the functions of MPK4 in plant growth/development and immunity. We discovered that the duration of the loss of MPK4 activity is important to plant immune responses. Short-term loss of MPK4 activity did not impact flg22-induced ROS burst or resistance against Pseudomonas syringae (Pst). Enhanced Pst resistance was only observed in the MPK4SR plants with stunted growth following prolonged inhibition of MPK4 activity. Transcriptome analyses in plants with short-term loss of MPK4 activity revealed a vital role of MPK4 in regulating several housekeeping processes, including mitosis, transcription initiation, and cell wall macromolecule catabolism. Furthermore, the constitutive weak activation of MPK4GA in the MPK4CA plants (genotype: PMPK4:MPK4GA mpk4) led to early flowering and premature senescence, which was associated with its compromised resistance against Pst. These findings suggest that MPK4 plays important roles in plant growth and development and in maintaining the delicate balance between growth/development and immune adaptation in plants.

S-palmitoylation of MAP kinase is essential for fungal virulence.

S-palmitoylation is an important reversible protein post-translational modification in organisms. However, its role in fungi is uncertain. Here, we found the treatment of the rice false fungus Ustilaginoidea virens with S-palmitoylation inhibitor 2 BP resulted in a significant decrease in fungal virulence. Comprehensive identification of S-palmitoylation sites and proteins in U. virens revealed a total of 4,089 S-palmitoylation sites identified among 2,192 proteins and that S-palmitoylated proteins were involved in diverse biological processes. Among the five palmitoyltransferases, UvPfa3 and UvPfa4 were found to regulate the pathogenicity of U. virens. We then performed quantitative proteomic analysis of ∆UvPfa3 and ∆UvPfa4 mutants. Interestingly, S-palmitoylated proteins were significantly enriched in the mitogen-activated protein kinase and autophagy pathways, and MAP kinase UvSlt2 was confirmed to be an S-palmitoylated protein which was palmitoylated by UvPfa4. Mutations of S-palmitoylation sites in UvSlt2 resulted in significantly reduced fungal virulence and decreased kinase enzymatic activity and phosphorylation levels. Simulations of molecular dynamics demonstrated mutation of S-palmitoylation sites in UvSlt2 causing decreased hydrophobic solvent-accessible surface area, thereby weakening the bonding force with its substrate UvRlm1. Taken together, S-palmitoylation promotes U. virens virulence through palmitoylation of MAP kinase UvSlt2 by palmitoyltransferase UvPfa4. This enhances the enzymatic phosphorylation activity of the kinase, thereby increasing hydrophobic solvent-accessible surface area and binding activity between the UvSlt2 enzyme and its substrate UvRlm1. Our studies provide a framework for dissecting the biological functions of S-palmitoylation and reveal an important role for S-palmitoylation in regulating the virulence of the pathogen.IMPORTANCES-palmitoylation is an important post-translational lipid modification of proteins. However, its role in fungi is uncertain. In this study, we found that S-palmitoylation promotes virulence of rice false smut fungus U. virens through palmitoylation of MAP kinase UvSlt2 by palmitoyltransferase UvPfa4. This enhances the enzymatic phosphorylation activity of the kinase, thereby increasing hydrophobic solvent-accessible surface area and binding activity between the UvSlt2 enzyme and its substrate UvRlm1. Our studies provide a framework for dissecting the biological functions of S-palmitoylation and reveal an important role for S-palmitoylation in regulating the virulence of the pathogen. This is the first functional study to reveal the role of S-palmitoylation in fungal virulence.

Exploring the potential mechanisms of polysaccharides against gastric ulcer: Network pharmacology analysis and molecular docking validation

AbstractGastric ulcer is a common peptic ulcer that affects human health and life quality seriously. As anti‐gastric ulcer drugs usually cause side‐effects, polysaccharides may be the potential alternatives because of better effectiveness and less toxicity. Although the anti‐gastric ulcer activities of polysaccharides have been widely reported, the mechanisms have not yet been well‐disclosed. In this study, network pharmacology analysis was performed to explore the potential mechanisms of polysaccharides against gastric ulcer, and the results were validated by molecular docking. Results indicated that β‐glucan, arabinogalactan, xylan, and arabinan were the key structures, and ABL1, AKT1, androgen receptor, epidermal growth factor receptor, v‐Ha‐ras Harvey rat sarcoma viral oncogene homolog, HSP90AA1, mitogen‐activated protein kinase 8 (MAPK8), MAPK14, NOS2, PIK3R1, RAC1, ras homolog gene family member A, and proto‐oncogene tyrosine‐protein kinase Src were the core targets for polysaccharides in treating gastric ulcer. Polysaccharides have influences on 1958 GO items and 199 KEGG pathways, and their anti‐gastric ulcer activities are related to MAPK, Ras, PI3K‐Akt, vascular endothelial growth factor, prolactin, FoxO and Rap1 signaling pathways, etc. Molecular docking validation showed that the results of network pharmacology analysis were credible, and interactions between polysaccharide structures and core targets were observed. This study contributes to understanding the mechanisms of polysaccharides in treating gastric ulcer and provides references for future activity screening and mechanism research in anti‐gastric ulcer.

Mechanisms of Bone Morphogenetic Protein 2 in Respiratory Diseases.

Bone morphogenetic protein 2 (BMP2) belongs to the transforming growth factor-β (TGF-β) superfamily and plays an important role in regulating embryonic development, angiogenesis, osteogenic differentiation, tissue homeostasis, and cancer invasion. Increasing studies suggest BMP2 is involved in several respiratory diseases. This study aimed to review the role and mechanisms of BMP2 in respiratory diseases. BMP2 signaling pathway includes the canonical and non-canonical signaling pathway. The canonical signaling pathway is the BMP2-SMAD pathway, and the non-canonical signaling pathway includes mitogen-activated protein kinase (MAPK) pathway and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. The BMP2 is related to pulmonary hypertension (PH), lung cancer, pulmonary fibrosis (PF), asthma, and chronic obstructive pulmonary disease (COPD). BMP2 inhibits the proliferation of pulmonary artery smooth muscle cells (PASMCs), promotes the apoptosis of PASMCs to reduce pulmonary vascular remodeling in PH, which is closely related to the canonical and non-canonical pathway. In addition, BMP2 stimulates the proliferation and migration of cells to promote the occurrence, colonization, and metastasis of lung cancer through the canonical and the non-canonical pathway. Meanwhile, BMP2 exert anti-fibrotic function in PF through canonical signaling pathway. Moreover, BMP2 inhibits airway inflammation to maintain airway homeostasis in asthma. However, the signaling pathways involved in asthma are poorly understood. BMP2 inhibits the expression of ciliary protein and promotes squamous metaplasia of airway epithelial cells to accelerate the development of COPD. In conclusion, BMP2 may be a therapeutic target for several respiratory diseases.

Macrophage-expressed coagulation factor 7 promotes adverse cardiac remodeling

Abstract Background Excess fibrotic remodeling leads to cardiac dysfunction in ischemic heart disease and is driven by MAP kinase-dependent transforming growth factor-ß1 (TGF-ß1) activation by coagulation signaling of myeloid cells. How coagulation-inflammatory circuits can be specifically targeted to achieve beneficial macrophage reprogramming after myocardial infarction (MI) is incompletely understood. Methods Mice with permanent ligation of the proximal left anterior descending artery (LAD) were used to model ischemic heart disease and analyzed by single cell RNA sequencing, protein expression changes, confocal microscopy, and longitudinal monitoring of recovery. We probed the role of the tissue factor (TF)-factor 7 (F7)-integrin ß1-protease activated receptor (PAR) 2 signaling complex by utilizing genetic mouse models and pharmacological intervention. Results Cleavage-insensitive PAR2R38E and myeloid cell integrin ß1-deficient mice had improved cardiac function after MI compared to controls. Proximity ligation assays of monocytic cells in the infarcted myocardium demonstrated that colocalization of F7 with integrin ß1 was diminished in monocyte/macrophage F7-deficient mice. F7fl/fl CX3CR1Cre relative to littermate control mice showed reduced TGF-ß1 and MAP kinase activation, as well as cardiac dysfunction after MI, despite unaltered overall recruitment of myeloid cells into the infarct zone. Single cell mRNA sequencing of CD45+ cells 3 and 7 days after MI uncovered a trajectory from ischemic myocardium-recruited monocytes to inflammatory TF+/F7+/TREM1+ macrophages. As early as 7 days after MI, macrophage F7-deletion led to an expansion of Olfml3+ macrophages with a reparative phenotype and, conversely, to a reduction of TF+/F7+/TREM1+ macrophages, which were also attenuated in activation-resistant PAR2R38E mice. To demonstrate the therapeutic potential of inhibiting the TF-F7-PAR2 signaling complex, we injected a specific monoclonal anti-TF antibody that lacks anticoagulant activity. Short-term treatment from day 1-5 after non-reperfused MI improved cardiac dysfunction, decreased excess fibrosis, attenuated vascular endothelial dysfunction, and increased survival 28 days after MI. Conclusion Extravascular TF-F7-PAR2 complex signaling drives inflammatory macrophage polarization in ischemic heart disease. Targeting this signaling complex for specific therapeutic macrophage reprogramming following MI attenuates cardiac fibrosis and improves cardiovascular function.

Antioxidant and Anti-Inflammatory Properties of Conceivable Compounds from Glehnia littoralis Leaf Extract on RAW264.7 Cells

Background/Objectives: Glehnia littoralis is a medicinal plant, but the scientific basis is still unclear. This study thoroughly investigated phenols from Glehnia littoralis extract (GLE) to determine their potential as anti-inflammatory and antioxidant agents. Methods: High-performance liquid chromatography (HPLC) and mass spectrometry (MS) were used to analyze the compounds in GLE. In addition, we performed GLE in vitro in macrophages after lipopolysaccharide (LPS)-induced inflammation. Results: The extract contained eight peaks representing phenolic compounds and one peak representing riboflavin, with the corresponding mass spectrometry data documented. These biologically active compounds were purified by ultrafiltration using LC to determine their ability to target cyclooxygenase-2 (COX-2) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). The results showed that significant compounds were identified, demonstrating a binding affinity for both COX-2 and DPPH. This suggests that the compounds showing excellent binding affinity for COX-2 and DPPH may be the main active ingredients. Vital inflammatory cytokines, including COX-2, inducible nitric oxide synthase (iNOS), mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB), were found to be down-regulated during the treatment. In addition, we revealed that the selected drugs exhibited potent binding capacity to inflammatory factors through molecular docking studies. In addition, we confirmed the presence of phenolic components in GLE extract and verified their possible anti-inflammatory and antioxidant properties. Conclusions: This study provided evidence for an efficient strategy to identify critical active ingredients from various medicinal plants. These data may serve as a baseline for further investigations of applying GLE in the pharmaceutical industry.

Probiotic Characteristics and the Anti-Inflammatory Effects of Lactiplantibacillus plantarum Z22 Isolated from Naturally Fermented Vegetables

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases.

Regulation of Catalase Expression and Activity by DhHog1 in the Halotolerant Yeast Debaryomyces hansenii Under Saline and Oxidative Conditions

Efficient transcriptional regulation of the stress response is critical for microorganism survival. In yeast, stress-related gene expression, particularly for antioxidant enzymes like catalases, mitigates reactive oxygen species such as hydrogen peroxide (H2O2), preventing cell damage. The halotolerant yeast Debaryomyces hansenii shows oxidative stress tolerance, largely due to high catalase activity from DhCTA and DhCTT genes. This study evaluates D. hansenii’s response to oxidative stress caused by H2O2 under saline conditions, focusing on cell viability, gene expression, and catalase activity. Chromatin organization in the promoter of DhCTA and DhCTT was analyzed, revealing low nucleosome occupancy in promoter regions, correlating with active gene expression. Stress-related motifs for transcription factors like Msn2/4 and Sko1 were found, suggesting regulation by the DhHog1 MAP kinase. Analysis of a Dhhog1Δ mutant showed DhHog1’s role in DhCTA expression under H2O2 or NaCl conditions. These findings highlight DhHog1’s critical role in regulating the stress response in D. hansenii, offering insights for enhancing stress tolerance in halotolerant yeasts, particularly for industrial applications in saline wastewater management.

Genome-Wide Analysis of the MAPKKK Gene Family Under Abiotic Stresses in Moso Bamboo (Phyllostachys edulis)

Mitogen-activated protein kinase kinase kinases (MAPKKKs) are the upstream components of MAPK cascades and are involved in mediating stress responses and developmental processes. Although MAPKKK genes have been investigated in many plants, the identification and characterization of MAPKKKs in moso bamboo were still limited. Here, 134 MAPKKKs were identified as unevenly distributed on 23 chromosomes (except for chromosome 1) of moso bamboo and divided into three subfamilies by phylogenetic analysis. The gene structure and conserved motif of PeMAPKKKs were investigated. The expansions of PeMAPKKKs were driven by whole-genome duplication (WGD) or segmental duplication events. The duplicated gene pairs were under purifying selection based on the Ka/Ks ratios, suggesting they underwent functional conservation. Most PeMAPKKKs contained cis-elements related to development, hormones, and stress responses. Tissue expression patterns showed that PeMAPKKKs had multiple expression patterns. The qPCR analysis showed distinct expression patterns of PeMAPKKKs under drought, salt, and cold stress conditions. Taken together, this study provides a solid foundation for future functional characterizations of MAPKKKs and identifies candidate stress-responsive genes for further study in moso bamboo.

Research progress on the mechanism of acupuncture on depression based on signaling pathway regulation

Depression is high in prevalence rate, recurrence rate and disability rate. Acupuncture is effective on depression. The paper reviewed the regulatory effect of acupuncture on five prominent signaling pathways, i.e. mitogen activated protein kinase (MAPK), Wnt/β-catenin, Notch, adenyl ate cyclase/cyclic adenosine phosphate/protein kinase (AC/cAMP/PKA) and NO/cyclic guanosine monophosphate (cGMP)； and elaborated the structure of each signaling pathway, the association with depression onset, and the relevant research progress of acupuncture in treatment of depression. In view of the regulation of signal pathways, acupuncture can up-regulate AC/cAMP/PKA and extracellular signal-regulated kinase (ERK), promote the expression of neurotrophic factors or Bcl-2, prevent from and repair neuronal damage, advance neurogenesis and improve synaptic plasticity； it can modulate the Wnt/β-catenin and Notch signal pathways to protect neurons and increase cell proliferation； and down-regulate JNK and up-regulate NO/cGMP signal pathways to inhibit stress that leads to abnormal apoptosis of neurosis and attenuate neurotoxicity and neuronal damage so that anti-depression of acupuncture is obtained. This review provides a new approach to the mechanism research of acupuncture in treatment of depression through regulating the relevant single pathways.

Functions and mechanisms of CDPKs in plant responses to abiotic stress

Calcium-dependent protein kinases (CDPKs/CPKs) are members of the Ca2+-sensitive Ser/Thr protein kinase family and play a crucial role in plant growth and development and responses to abiotic stress. CDPKs are capable of rapidly sensing changes in intracellular Ca2+ signals and recognizing and phosphorylating specific substrates, thereby transmitting and amplifying Ca2+ signal cascades downstream. They are involved in plant responses to stress conditions such as drought, saline-alkali stress, and injuries and regulate plant growth and development, gene expression, ion channel activity, and stomatal movement. The autophosphorylation of CDPKs can affect their activities and substrate specificity. CDPKs have the ability to bind to and phosphorylate multiple substrates. In addition to participating in respiratory burst oxidase homolog (RBOH), mitogen-activated protein kinase (MAPK), and plant hormone signaling pathways, CDPKs can also bind to 14-3-3 proteins, which enables the regulation of plant responses to stress and promotes plant growth and development. This paper summarized the research findings on the discovery, structure, classification, and roles of CDPKs in plant responses to stress and proposed the future research directions, aiming to provide the genetic resources and a theoretical basis for improving the stress tolerance of crops.

CD36 deficiency protects lipopolysaccharide-induced sepsis via inhibiting CerS6-mediated endoplasmic reticulum stress

The type 2 scavenger receptor CD36 functions not only as a long chain fatty acid transporter, but also as a pro-inflammatory mediator. Ceramide is the simple N-acylated form of sphingosine and exerts distinct biological activity depending on its acyl chain length. Six ceramide synthases (CerS) in mammals determine the chain length of ceramide species, and CerS6 mainly produces C16-ceramide. Endotoxin-induced septic shock shows high mortality, but the pathophysiologic role of sphingolipids involved in this process has been hardly investigated. This paper aims to highlight the different role of CerS isoforms in endotoxin-induced inflammatory responses and the regulatory role of CD36 in CerS6 protein degradation with an emphasis as the potential therapeutic candidates in humans. Lipopolysaccharide (LPS), the endotoxin of the Gram-negative bacterial cell wall, was treated to induce endotoxin-induced inflammation both in vitro and in vivo. CerS6-derived C16-ceramide propagated LPS-induced inflammatory responses activating various intracellular signaling pathways, such as mitogen-activated protein kinase and nuclear factor-κB, resulting in the formation of inflammasome complex and pro-inflammatory cytokines. Mechanistically, CerS6-derived C16-ceramide augmented inflammatory responses via endoplasmic reticulum stress, and CerS6 protein stability was regulated by CD36. Finally, CerS6 protein expression and LPS-induced lethality were strikingly reduced in CD36 knockout mice. Collectively, our findings show that CerS6-derived C16-ceramide plays a pivotal role in endotoxin-induced inflammation and suggest CerS6 and its regulator CD36 as possible targets for therapy under life-threatening inflammation such as septic shock.

Immunostimulation Signaling via Toll-like Receptor 2 Activation: A Molecular Mechanism of Lactococcus lactis OTG1204 In Vitro and In Vivo

Introduction: The immune system’s defense against pathogens involves innate and adaptive responses, crucial in maintaining overall health. Immunosuppressed states render individuals more susceptible to potential diseases, indicating the need for effective strategies to bolster immune functions. Objectives: Although the immunostimulatory effects of various probiotics have been studied, the specific effects and molecular mechanisms of Lactococcus lactis OTG1204 (OTG1204) remain unknown. In this study, the aim was to investigate the molecular mechanisms of OTG1204 in RAW 264.7 macrophages, the key effector cells of the innate immune system involved in host defense and inflammatory responses. Additionally, in this study, the effects of OTG1204 on cyclophosphamide (CTX)-induced immunosuppression states were investigated, thereby demonstrating its potential as an immune stimulant. Methods: To assess the macrophage activation ability and underlying mechanisms of OTG1204, RAW 264.7 cells were utilized with transfection, enzyme-linked immunosorbent assay, and quantitative real-time PCR analyses. Furthermore, to evaluate the immunostimulatory effects under immunosuppressed conditions, CTX-induced immunosuppression mice model was employed, and analyses were performed using hematoxylin and eosin staining, flow cytometry, and microbiota examination. Results: OTG1204 activated RAW 264.7 macrophages, leading to increased production of nitric oxide, prostaglandin E2, and cytokines. This immune activation was mediated through the upregulation of toll-like receptor 2, which subsequently activated the nuclear factor-κB (NF-kB) and mitogen-activated protein kinase (MAPK)/activator protein 1 (AP-1) pathways, thereby stimulating the immune response. In CTX-treated mice, OTG1204 recovered body weight, spleen, and mesenteric lymph node indices, and natural killer cell activity. It re-established populations of innate and adaptive immune cells and activated T cells to secrete cytokines. We also examined the gut barrier integrity and microbiota composition to assess OTG1204’s impact on intestinal health, as these factors play a significant role in immune enhancement. OTG1204 enhanced gut barrier integrity by upregulating mucin 2 and tight junction proteins and modulated the gut microbiota by restoring the Firmicutes/Bacteroidetes balance and reducing the abundance of Actinobacteria and Tenericutes. Conclusion: These results suggest that OTG1204 may serve as an effective probiotic for immune enhancement and gut health management by targeting the NF-κB and MAPK/AP-1 pathways, with minimal side effects.

Integrating network pharmacology, molecular docking, and experimental validation to reveal the mechanism of Radix Rehmanniae in psoriasis.

Radix Rehmanniae (RR) plays an important role in treating psoriasis. However, the active compounds of RR and potential mechanisms are unclear. The current study was designed to investigate the potential active ingredients, targets, and mechanisms of RR in treating psoriasis through network pharmacology, molecular docking, and vitro experiments. Initially, the TCMSP database and literature retrieval were used to access the active ingredients of RR. The psoriasis target proteins were obtained from Therapeutic Target Database, OMIM, GeneCards, and DrugBank databases. The target proteins were then converted into target genes using Uniprot. Secondly, overlapping genes were obtained through Venn online tool. Then, protein-protein interactions network diagram is finished by STRING database. Next, Cytoscape software was used to acquire the top 10 hub proteins; gene ontology and Kyoto encyclopedia of genes and genomes enrichment analysis were then used to predict possible mechanisms. Afterwards, molecular docking validation of the active ingredients with the main targets was performed by AutoDock software. Finally, lipopolysaccharides induced RAW264.7, to assess the effects and molecular mechanisms by MTT, RT-qPCR, and Western blot assays. Overall, there are 20 effective compounds and 33 targets involved in biological processes including apoptosis, intracellular signaling, vasodilation, and mitogen-activated protein kinase (MAPK) signaling cascade. The docking results showed strong binding capacity between the active ingredients and targets. We verified aucubin as the key active ingredient, tumor necrosis factor α, and IL6 as the core targets, and focused on the p38MAPK protein pathway. Cellular experiments showed that aucubin down-regulated the phosphorylated p38MAP protein and reduced the expression of tumor necrosis factor α mRNA, IL6 mRNA, and IL1βmRNA. In summary, RR is featured with multicomponent, multi-target, and multi-pathway in treating psoriasis; the preliminary mechanism may be associated with the down-regulation of p38MAPK phosphorylation and curbing the expression of inflammatory factor by aucubin. This paper provides the scientific basis for Traditional Chinese medicine treating psoriasis.

Comparative transcriptome analysis of cucumber fruit tissues reveals novel regulatory genes in ascorbic acid biosynthesis.

Ascorbic acid (AsA) is one of the most abundant natural antioxidants, and it is an important indicator of the nutritional value of cucumber fruit. The aim of this study was to elucidate the regulatory mechanism affecting AsA metabolism in cucumber fruit. In this study, the AsA content in the fruit of two cucumber cultivars (H28 and H105) was significantly higher in the exocarp and endocarp than in the mesocarp. To clarify the regulation of AsA in cucumber fruit, the transcriptomes of three fruit tissues (i.e., the exocarp, mesocarp, and endocarp) of two cucumber cultivars (H28 and H105) were sequenced. Transcriptomic profiling combined with transcription factors (TFs) and correlation analysis were performed to reveal that three genes, including CsaV3_5G014110 (phosphomannomutase, PMM), CsaV3_2G004170 (GDP-mannose-3', 5'-epimerase, GME) and CsaV3_5G006680 (dehydroascorbate reductase, DHAR), were expressed at higher level in the exocarp and endocarp than in the mesocarp. In both two cultivars, CsaV3_4G028360 (ethylene-responsive transcription factor, ERF) was negatively correlated with PMM and GME, and positively correlated with DHAR. CsaV3_6G042110 (ethylene-responsive transcription factor, ERF) was positively correlated with PMM and GME, and negatively correlated with DHAR. CsaV3_6G032360 (mitogen-activated protein kinase, MAPK) as positively correlated with PMM, GME and DHAR. These six genes are considered the key candidate genes for further research. This study provides insight for further study on the regulation of AsA biosynthesis in cucumber fruit and provide potential candidate genes for future genetic improvement of cucumber germplasm with enhanced AsA accumulation.

Paraptosis—A Distinct Pathway to Cell Death

Cell death is a critical biological process necessary for development, tissue maintenance, and defense against diseases. To date, more than 20 forms of cell death have been identified, each defined by unique molecular pathways. Understanding these different forms of cell death is essential for investigating the pathogenesis of diseases such as cancer, neurodegenerative disorders, and autoimmune conditions and developing appropriate therapies. Paraptosis is a distinct form of regulated cell death characterized by cytoplasmic vacuolation and dilatation of cellular organelles like the mitochondria and endoplasmic reticulum (ER). It is regulated by several signaling pathways, for instance, those associated with ER stress, calcium overload, oxidative stress, and specific cascades such as insulin-like growth factor I receptor (IGF-IR) and its downstream signaling pathways comprising mitogen-activated protein kinases (MAPKs) and Jun N-terminal kinase (JNK). Paraptosis has been observed in diverse biological contexts, including development and cellular stress responses in neuronal, retinal, endothelial, and muscle cells. The induction of paraptosis is increasingly important in anticancer therapy, as it targets non-apoptotic stress responses in tumor cells, which can be utilized to induce cell death. This approach enhances treatment efficacy and addresses drug resistance, particularly in cases where cancer cells are resistant to apoptosis. Combining paraptosis-inducing agents with traditional therapies holds promise for enhancing treatment efficacy and overcoming drug resistance, suggesting a valuable strategy in anticancer therapy.

Functional analysis of TkWRKY33: A key regulator in drought-induced natural rubber synthesis in Taraxacum kok-saghyz

WRKY proteins, which form a transcription factor superfamily that responds to jasmonic acid (JA) signals, regulate various developmental processes and stress responses in plants, including Taraxacum kok-saghyz (TKS). TKS serves as an ideal model plant for studying rubber production and lays the foundation for a comprehensive understanding of JA-mediated regulation of natural rubber synthesis. In the present study, we screened and identified a valuable transcription factor, TkWRKY33, based on transcriptome data from TKS in response to JA. We investigated its role in the regulation of natural rubber synthesis within the JA signaling pathway and its function in response to drought stress. Through protein-protein interactions and transcriptional regulation analysis, we found that TkWRKY33 may regulate natural rubber synthesis through the JA-TkMPK3-TkWRKY33-(TkGGPS5/TkACAT8) cascade pathway, possibly by participating in JA-activated mitogen-activated protein kinase (MAPK) signaling. Overexpression of TkWRKY33 in tobacco, along with functional analysis of drought resistance and comparative analysis of natural rubber content after drought stress, revealed that TkWRKY33 not only enhances plant drought resistance by regulating the expression of genes related to reactive oxygen species (ROS) scavenging through the JA signaling pathway, but also has a close relationship with the signal transduction pathway mediated by the JA hormone in regulating natural rubber synthesis.The TkWRKY33 is recognized as a valuable transcription factor, which likely plays a role in regulating natural rubber biosynthesis through the JA-activated MAPK cascade signaling pathway JA-TkMPK3-TkWRKY33-(TkGGPS5/TkACAT8).

GmWRKY33A positively regulates disease resistance in soybean (Glycine max)

The WRKY transcription factor gene family is a plant-specific transcription factor that plays important roles defense responses. Studies in model plant Arabidopsis demonstrated that WRKYs function downstream of mitogen activated-protein kinase (MAPK) signaling cascade and participate in defense responses through activating the expression of defense-related genes. However, the roles of WRKYs in defense responses have not been previously investigated in paleopolyploidy soybean. Bioinfomatic analysis revealed that there are three pair of GmWRKY33 genes in the soybean genome. The identity of first two pair of GmWRKY33 genes is greater than 84% (named as GmWRKY33A). The identity of genes within the same pair is greater than 95%. A 300 bp fragment highly homologous to these four GmWRKY33A was chosen to clone into bean pod mosaic virus (BPMV)-based silencing vector (BPMV-VIGS) to achieve the goal of silencing four GmWRKY33A genes simultaneously. In this study, we simultaneously silenced four homologous genes of GmWRKY33A using a bean pod mottle virus (BPMV) vector carrying a single fragment of GmWRKY33A. Comparing the silenced plants with the vector control plants, no evident morphological phenotypes were observed. However, the GmWRKY33A-silenced plants exhibited significantly reduced resistance to Pseudomonas syringae pv. glycinea (Psg), Xanthomonas axonopodis pv. glycine (Xag), as well as to soybean mosaic virus (SMV). Furthermore, we demonstrated that silencing these GmWRKY33A genes significantly inhibited the activation of GmMPK3/GmMPK6 induced by Psg infection. Collectively, our results suggest that GmWRKY33As are involved in soybean immunity through regulating the transcription of GmMPK3/6 genes or activating the kinase activities of GmMPK3/6. Taken together, our results demonstrated that GmWRKY33As are positive regulators of soybean immune responses.

The combined analysis of transcriptome and phytohormone provides new insights into signaling mechanism for lateral root formation of tea plant (Camellia sinensis)

The growth and development of lateral roots (LRs) determine the nutrient absorption and environmental adaptability of tea plant, playing a crucial role in the economic efficiency of tea plantations. However, the molecular mechanisms underlying the formation of LRs in tea plant remain unreported. In this study, we established a LRs induction system in tea plants by exogenously adding N-1-naphthylphthalamic acid (NPA) and naphthaleneacetic acid (NAA). The molecular mechanisms of LRs formation were analyzed through transcriptomics and endogenous hormone measurements. Results showed that NAA treatment could counteract the inhibitory effect of NPA on LRs formation and promote the generation of LRs in tea plant. The addition of exogenous NAA reduced the levels of auxin and zeatin in the root tips while increasing the content of abscisic acid (ABA). Transcriptomic analysis at four time points (2, 6, 12, and 24 h) after NAA vs. MOCK treatment revealed 78 different expression genes (DEGs) associated with plant hormone signaling pathways. Among these, the auxin signaling pathway was the most significant in responding to the LRs formation in tea plant. Weighted Gene Co-Expression Network Analysis (WGCNA) identified the Mitogen-Activated Protein Kinases (MAPK) signaling pathway as responsive to NAA treatment, participating in the formation of LRs in tea plant. This study provides potential signaling pathways for the investigation of LRs formation in tea plant and identifies candidate genes for further research into tea plant root system architecture (RSA).

Arabidopsis uses a molecular grounding mechanism and a biophysical circuit breaker to limit floral abscission signaling

Abscission is the programmed separation of plant organs. It is widespread in the plant kingdom with important functions in development and environmental response. In Arabidopsis, abscission of floral organs (sepals, petals, and stamens) is controlled by two receptor-like protein kinases HAESA (HAE) and HAESA LIKE-2 (HSL2), which orchestrate the programmed dissolution of the abscission zone connecting floral organs to the developing fruit. In this work, we use single-cell RNA sequencing to characterize the core HAE/HSL2 abscission gene expression program. We identify the MAP KINASE PHOSPHATASE-1/MKP1 gene as a negative regulator of this pathway. MKP1 acts prior to activation of HAE/HSL2 signaling to establish a signaling threshold required for the initiation of abscission. Furthermore, we use single-cell data to identify genes expressed in two subpopulations of abscission zone cells: those proximal and those distal to the plane of separation. We identify INFLORESCENCE DEFICIENT IN ABSCISSION/IDA family genes, encoding activating ligands of HAE/HSL2, as enriched in distal abscission zone cells at the base of the abscising organs. We show how this expression pattern forms a biophysical circuit breaker whereby, when the organ is shed, the source of the IDA peptides is removed, leading to cessation of HAE/HSL2 signaling. Overall, this work provides insight into the multiple control mechanisms acting on the abscission-signaling pathway.