CARD9+ microglia promote antifungal immunity via IL-1ß- and CXCL1-mediated neutrophil recruitment.

The C-type lectin receptor-Syk (spleen tyrosine kinase) adaptor CARD9 facilitates protective antifungal immunity within the central nervous system (CNS), as human deficiency in CARD9 causes susceptibility to fungus-specific, CNS-targeted infection. CARD9 promotes the recruitment of neutrophils to the fungus-infected CNS, which mediates fungal clearance. In the present study we investigated host and pathogen factors that promote protective neutrophil recruitment during invasion of the CNS by Candida albicans. The cytokine IL-1ß served an essential function in CNS antifungal immunity by driving production of the chemokine CXCL1, which recruited neutrophils expressing the chemokine receptor CXCR2. Neutrophil-recruiting production of IL-1ß and CXCL1 was induced in microglia by the fungus-secreted toxin Candidalysin, in a manner dependent on the kinase p38 and the transcription factor c-Fos. Notably, microglia relied on CARD9 for production of IL-1ß, via both transcriptional regulation of Il1b and inflammasome activation, and of CXCL1 in the fungus-infected CNS. Microglia-specific Card9 deletion impaired the production of IL-1ß and CXCL1 and neutrophil recruitment, and increased fungal proliferation in the CNS. Thus, an intricate network of host-pathogen interactions promotes antifungal immunity in the CNS; this is impaired in human deficiency in CARD9, which leads to fungal disease of the CNS.

Sleep deprivation reduced LPS-induced IgG2b production by up-regulating BMAL1 and CLOCK expression.

Sleep deprivation (SD) weakens the immune system and leads to increased susceptibility to infectious or inflammatory diseases. However, it is still unclear how SD affects humoral immunity. In the present study, sleep disturbance was conducted using an sleep deprivation instrument, and the bacterial endotoxin lipopolysaccharide (LPS) was used to activate the immune response. It was found that SD-pretreatment reduced LPS-induced IgG2b+ B cells and IgG2b isotype antibody production in lymphocytes of spleen. And, SD-pretreatment decreased the proportion of CD4+T cells, production of CD4+T cells derived TGF-ß1 and its contribution in helping IgG2b production. Additionally, BMAL1 and CLOCK were selectively up-regulated in lymphocytes after SD. Importantly, BMAL1 and CLOCK deficiency contributed to TGF-ß1 expression and production of IgG2b+ B cells. Thus, our results provide a novel insight to explain the involvement of BMAL1 and CLOCK under SD stress condition, and their roles in inhibiting TGF-ß1 expression and contributing to reduction of LPS induced IgG2b production.

[Optimization of ethanol reflux extraction process of Ziziphi Spinosae Semen- Schisandrae Sphenantherae Fructus based on network pharmacology combined with response surface methodology].

The present study optimized the ethanol extraction process of Ziziphi Spinosae Semen-Schisandrae Sphenantherae Fructus drug pair by network pharmacology and Box-Behnken method. Network pharmacology and molecular docking were used to screen out and verify the potential active components of Ziziphi Spinosae Semen-Schisandrae Sphenantherae Fructus, and the process evaluation indexes were determined in light of the components of the content determination under Ziziphi Spinosae Semen and Schisandrae Sphenantherae Fructus in the Chinese Pharmacopoeia(2020 edition). The analytic hierarchy process(AHP) was used to determine the weight coefficient of each component, and the comprehensive score was calculated as the process evaluation index. The ethanol extraction process of Ziziphi Spinosae Semen-Schisandrae Sphenantherae Fructus was optimized by the Box-Behnken method. The core components of the Ziziphi Spinosae Semen-Schisandrae Sphenantherae Fructus drug pair were screened out as spinosin, jujuboside A, jujuboside B, schisandrin, schisandrol, schisandrin A, and schisandrin B. The optimal extraction conditions obtained by using the Box-Behnken method were listed below: extraction time of 90 min, ethanol volume fraction of 85%, and two times of extraction. Through network pharmacology and molecular docking, the process evaluation indexes were determined, and the optimized process was stable, which could provide an experimental basis for the production of preparations containing Ziziphi Spinosae Semen-Schisandrae Sphenantherae Fructus.

The E3 ubiquitin ligase Itch deficiency promotes antigen-driven B-cell responses in mice.

Deficiency of Itch, an E3 ubiquitin ligase, usually induced severe systemic and progressive autoimmune disease. The Itch function is well studied in T cells but not in B cells. We hypothesize that B-cell-specific Itch deficiency promoted antigen-induced B-cell activation and antibody-expressing plasma cell (PC) production. We found that unlike Itch KO, Itch cKO (CD19cre Itchf/f ) mice did not demonstrated a significant increase in the sizes of spleens and LNs, antibody level, and base mutation of antibody gene. However, in line with the fact that Itch expression decreased in GC B cells, PCs, and plasmablast (PB)-like SP 2/0 cells, Itch deficiency promoted B-cell activation and antibody production induced by antigens including lipopolysaccharide (LPS) and sheep red blood cells (SRBCs). Mechanistically, we found that Itch deficiency promotes antigen-induced cytokine production because Itch controls the proteins (e.g., eIF3a, eIF3c, eIF3h) with translation initiation factor activity. Altogether, our data suggest that Itch deficiency promotes antigen-driven B-cell response. This may provide hints for Itch-targeted treatment of patients with autoimmune disease.

Urokinase-type plasminogen activator receptor (uPAR) as a therapeutic target in cancer.

Urokinase-type plasminogen activator receptor (uPAR) is an attractive target for the treatment of cancer, because it is expressed at low levels in healthy tissues but at high levels in malignant tumours. uPAR is closely related to the invasion and metastasis of malignant tumours, plays important roles in the degradation of extracellular matrix (ECM), tumour angiogenesis, cell proliferation and apoptosis, and is associated with the multidrug resistance (MDR) of tumour cells, which has important guiding significance for the judgement of tumor malignancy and prognosis. Several uPAR-targeted antitumour therapeutic agents have been developed to suppress tumour growth, metastatic processes and drug resistance. Here, we review the recent advances in the development of uPAR-targeted antitumor therapeutic strategies, including nanoplatforms carrying therapeutic agents, photodynamic therapy (PDT)/photothermal therapy (PTT) platforms, oncolytic virotherapy, gene therapy technologies, monoclonal antibody therapy and tumour immunotherapy, to promote the translation of these therapeutic agents to clinical applications.

Pyrroloquinoline quinone ameliorates diabetic cardiomyopathy by inhibiting the pyroptosis signaling pathway in C57BL/6 mice and AC16 cells.

PURPOSE: Diabetic cardiomyopathy (DCM), a common complication of diabetes mellitus and is characterized by myocardial hypertrophy and myocardial fibrosis. Pyrroloquinoline quinone (PQQ), a natural nutrient, exerts strong protection against various myocardial diseases. Pyroptosis, a type of inflammation-related programmed cell death, is vital to the development of DCM. However, the protective effects of PQQ against DCM and the associated mechanisms are not clear. This study aimed to investigate whether PQQ protected against DCM and to determine the underlying molecular mechanism. METHODS: Diabetes was induced in mice by intraperitoneal injection of streptozotocin, after which the mice were administered PQQ orally (10, 20, or 40 mg/kg body weight/day) for 12 weeks. AC16 human myocardial cells were divided into the following groups and treated accordingly: control (5.5 mmol/L glucose), high glucose (35 mmol/L glucose), and HG + PQQ groups (1 and 10 nmol/L PQQ). Cells were treated for 24 h. RESULTS: PQQ reduced myocardial hypertrophy and the area of myocardial fibrosis, which was accompanied by an increase in antioxidant function and a decrease in inflammatory cytokine levels. Moreover, myocardial hypertrophy-(ANP and BNP), myocardial fibrosis-(collagen I and TGF-ß1), and pyroptosis-related protein levels decreased in the PQQ treatment groups. Furthermore, PQQ abolished mitochondrial dysfunction and the activation of NF-κB/IκB, and decreased NLRP3 inflammation-mediated pyroptosis in AC16 cells under high-glucose conditions. CONCLUSION: PQQ improved DCM in diabetic mice by inhibiting NF-κB/NLRP3 inflammasome-mediated cell pyroptosis. Long-term dietary supplementation with PQQ may be greatly beneficial for the treatment of DCM. Diagram of the underlying mechanism of the effects of PQQ on DCM. PQQ inhibits ROS generation and NF-κB activation, which stimulates activation of the NLRP3 inflammasome and regulates the expression of caspase-1, IL-1ß, and IL-18. The up-regulated inflammatory cytokines trigger myocardial hypertrophy and cardiac fibrosis and promote the pathological process of DCM.

Review targeted drug delivery systems for norcantharidin in cancer therapy.

Norcantharidin (NCTD) is a demethylated derivative of cantharidin (CTD), the main anticancer active ingredient isolated from traditional Chinese medicine Mylabris. NCTD has been approved by the State Food and Drug Administration for the treatment of various solid tumors, especially liver cancer. Although NCTD greatly reduces the toxicity of CTD, there is still a certain degree of urinary toxicity and organ toxicity, and the poor solubility, short half-life, fast metabolism, as well as high venous irritation and weak tumor targeting ability limit its widespread application in the clinic. To reduce its toxicity and improve its efficacy, design of targeted drug delivery systems based on biomaterials and nanomaterials is one of the most feasible strategies. Therefore, this review focused on the studies of targeted drug delivery systems combined with NCTD in recent years, including passive and active targeted drug delivery systems, and physicochemical targeted drug delivery systems for improving drug bioavailability and enhancing its efficacy, as well as increasing drug targeting ability and reducing its adverse effects.

Gm40600 promotes CD4+ T-cell responses by interacting with Ahnak.

It is important to characterize novel proteins involved in T- and B-cell responses. Our previous study demonstrated that a novel protein, Mus musculus Gm40600, reduced the proliferation of Mus musculus plasmablast (PB)-like SP 2/0 cells and B-cell responses induced in vitro by LPS. In the present study, we revealed that Gm40600 directly promoted CD4+ T-cell responses to indirectly up-regulate B-cell responses. Importantly, we found that CD4+ T-cell responses, including T-cell activation and differentiation and cytokine production, were increased in Gm40600 transgenic (Tg) mice and were reduced in Gm40600 knockout (KO) mice. Finally, we demonstrated that Gm40600 promoted the Ahnak-mediated calcium signalling pathway by interacting with Ahnak to maintain a cytoplasmic lateral location of Ahnak in CD4+ T cells. Collectively, our data suggest that Gm40600 promotes CD4+ T-cell activation to up-regulate the B-cell response via interacting with Ahnak to promote the calcium signalling pathway. The results suggest that targeting Gm40600 may be a means to control CD4+ T-cell-related diseases.

[Quality evaluation of Aralia taibaiensis based on spectrum-activity relationship].

A spectrum-activity relationship is established with high performance liquid chromatography(HPLC) fingerprints and the in vitro antioxidant activity to improve the quality evaluation system of Aralia taibaiensis. The HPLC profiles of 12 batches of samples were collected, and the similarity evaluation, heat map analysis and principal component analysis were conducted for the chemometric study of the fingerprint data. Combined with grey correlation analysis, the contributions of the common peaks in the fingerprints to the antioxidant activity were clarified, and the important peaks reflecting the efficacy were identified. The results showed that 17 common peaks were found in 12 batches of A. taibaiensis samples, and 6 of them were identified as saponins. Similarity evaluation, heat map analysis and principal component analysis roughly classified the A. taibaiensis herbs into two categories, i.e.,(1) S1-S10, S12 and(2) S11. Twelve batches of samples showed different antioxidant activities in a dose-dependent manner. In particular, S9 had the strongest antioxidant activity, while S11 was the weakest in antioxidant capacity, which was basically consistent with the overall score results. The results of grey correlation analysis demonstrated that the 17 common peaks scavenged DPPH radicals in the following order: X_3>X_(17)>X_4>X_8>X_7>X_(13)>X_2>X_6>X_(11)>X_(10)>X_(16)>X_(12)>X_9>X_5>X_(14)>X_1>X_(15), and scavenged ABTS radicals in the order of X_4>X_3>X_7>X_8>X_2>X_(17)>X_(13)>X_6>X_(16)>X_(11)>X_5>X_(12)>X_(10)>X_9>X_(14)>X_1>X_(15). Among them, X_3, X_4, X_7(araloside C), X_8 and X_(17) were the important peaks reflecting the efficacy of A. taibaiensis, which were basically consistent with those contained in the principal component 1. In this study, the correlation between the HPLC fingerprints of 12 batches of A. taibaiensis and its antioxidant activity provides a reference for the Q-marker screening and quality control of A. taibaiensis.

Gm40600 suppressed SP 2/0 isograft tumor by reducing Blimp1 and Xbp1 proteins.

BACKGROUND: Multiple myeloma (MM), characterized by cancerous proliferation of plasmablasts (PB) and plasma cells (PC), remains incurable in many patients. Differentially expressed molecules between MM PCs and healthy PCs have been explored in order to identify novel targets for treating MM. In the present study, we searched for novel MM therapeutic targets by comparing mRNA expression patterns between the Mus musculus myeloma plasmablast-like SP 2/0 cell line and LPS-induced PB/PC. METHODS: Gene expression profiles of LPS-induced PB/PC and SP 2/0 cells were determined using RNA-sequencing. A predicted gene (Gm40600) was found to be expressed at a low level in SP 2/0 cells. To study the role of Gm40600 in malignant PC, Gm40600 cDNA was cloned into a lentiviral vector (LV201) containing a puromycin selectable marker that was then transfected into SP 2/0 cells. Stable Gm40600-expressing SP 2/0 cells were selected using puromycin. The effect of Gm40600 on SP 2/0 cell proliferation, cell cycle/apoptosis, and tumor progression was assessed by cell counting kit-8 (CCK8), flow cytometry (FACS), and the SP 2/0 isograft mouse model, respectively. The effect of Gm40600 on mRNA and protein expression was evaluated by RNA-sequencing and western blotting, respectively. RESULTS: We found that SP 2/0 cells expressed lower level of Gm40600 mRNA as compared to LPS-induced PB/PC. Overexpression of Gm40600 significantly suppressed SP 2/0 cell proliferation and isograft tumor progression in an isograft mouse model by promoting apoptosis. In addition, Gm40600 overexpression suppressed transcription of the gene encoding Bcl2. Gm40600 overexpression also reduced the expression of PC-associated transcription factors Blimp1 and Xbp1, which promote transcription of the gene that encodes Bcl2. CONCLUSIONS: Gm40600 reduced SP 2/0 cell proliferation and isograft tumor growth and progression by suppressing Blimp1 and Xbp1-mediated Bcl2 transcription to induce apoptosis. Thus, regulation of a human homolog of Gm40600, or associated factors, may be a potential therapeutic approach for treating MM.

Integrated proteomic and metabolomic analysis of a reconstructed three-species microbial consortium for one-step fermentation of 2-keto-L-gulonic acid, the precursor of vitamin C.

Microbial consortia, with the merits of strong stability, robustness, and multi-function, played critical roles in human health, bioenergy, and food manufacture, etc. On the basis of 'build a consortium to understand it', a novel microbial consortium consisted of Gluconobacter oxydans, Ketogulonicigenium vulgare and Bacillus endophyticus was reconstructed to produce 2-keto-L-gulonic acid (2-KGA), the precursor of vitamin C. With this synthetic consortium, 73.7 g/L 2-KGA was obtained within 30 h, which is comparable to the conventional industrial method. A combined time-series proteomic and metabolomic analysis of the fermentation process was conducted to further investigate the cell-cell interaction. The results suggested that the existence of B. endophyticus and G. oxydans together promoted the growth of K. vulgare by supplying additional nutrients, and promoted the 2-KGA production by supplying more substrate. Meanwhile, the growth of B. endophyticus and G. oxydans was compromised from the competition of the nutrients by K. vulgare, enabling the efficient production of 2-KGA. This study provides valuable guidance for further study of synthetic microbial consortia.

Distribution and elimination of quinocetone and its major metabolites in Cherry Valley ducks.

We examined the tissue distribution and elimination of quinocetone (QCT) and its major metabolites 1-desoxyquinocetone (1-DQCT), di-desoxyquinocetone (BDQCT), and 3-methyl-quinoxaline-2-carboxylic (MQCA) in ducks. The analytes were simultaneously quantitated using a UPLC-MS/MS method after oral administration of QCT at 100 mg·kg-1 day-1 for 7 days. We found that QCT and its major metabolites were widely distributed in duck tissues. The concentrations indicated that the primary compound in the liver, kidney, and heart was MQCA and the primary compound in the stomach, intestine, spleen, and lung was QCT. We also identified that MQCA was the most appropriate compound for QCT residue monitoring. The liver and kidney are the primary QCT target organs in ducks, and this study provides clear monitoring tools and important data to evaluate its safety.

Increased mTOR cancels out the effect of reduced Xbp-1 on antibody secretion in IL-1α-deficient B cells.

IL-1α in vitro promotes immunoglobulin secretion by inducing proliferation of mature B cells, whereas IL-1α deficiency has no effect on in vivo antibody production. However, the reason IL-1α deficiency does not reduce in vivo antibody production is still unclear. In this study, we found that similar as in vivo data, IL-1α deficiency did not affect antibody production in in vitro LPS-stimulated B cells. Surprisingly, LPS-stimulated IL-1α-/- B cells reduced a key antibody production-related transcription factor X-box binding protein 1 (Xbp-1) expression. Furthermore, we found that IL-1α deficiency up-regulated mTOR expression, which bypassed Xbp-1 for immunoglobulin secretion. Finally, we showed that Xbp-1 suppressed mTOR expression, whereas mTOR suppressed the activation of Xbp-1 promoter via JunB. Together, these data suggest that IL-1a deficiency reduced Xbp-1 and up-regulated mTOR. This may explain why IL-1α deficiency has no effect on antibody production.

BC094916 suppressed SP 2/0 xenograft tumor by down-regulating Creb1 and Bcl2 transcription.

BACKGROUND: Both multiple myeloma (MM) and systemic lupus erythematosus (SLE) are associated with abnormal production of plasma cells, although their pathological mechanism of each disease is different. The main characteristic of both diseases is uncontrolled differentiation of B cells into plasmablast/plasma cells. Despite continuous research on prognostic factors and the introduction of new agents for MM and SLE, treatments still do not exist for controlling plasmablast/plasma cells. Thus, it is necessary to identify novel therapeutic targets of plasmablast/plasma cells. Because of its plasmablast-like characteristics, the mus musculus myeloma SP 2/0 cell line was used in this study to test the effect of a novel therapeutic agent (BC094916 overexpression) on plasmablast/plasma cells. METHODS: We first determined gene expression profiles of plasma cells using Affymetrix microarrays and RNA-sequencing. The effect of BC094916 on SP 2/0 cell proliferation, cell cycle, and apoptosis was determined by CCK8 and fluorescence-activated cell sorting. The SP 2/0 xenograft mouse model was used to assess the impact of BC094916 on tumor progression. The luciferase reporter system was used to evaluate the effect of BC094916 on Creb1 and Bcl2 transcription. RESULTS: We found that BC094916 mRNA was decreased in plasma cells. The mouse myeloma cell line SP 2/0 expressed low levels of BC094916 mRNA, whereas BC094916 overexpression suppressed SP 2/0 cell proliferation by inducing apoptosis. BC094916 overexpression suppressed tumor progression in the SP 2/0 xenograft mouse model. We also found that BC094916 mediate apoptosis by suppressing transcription of the Creb1 and Bcl2 genes, which promote the transcription of eukaryotic translation initiation and elongation factor genes. CONCLUSIONS: BC094916 overexpression suppressed Creb1 and Bcl2 transcription to induce cell apoptosis, which suppressed SP 2/0 proliferation and xenograft tumor progression. Thus, BC094916 overexpression may be a potential therapeutic agent for treatment of MM and autoimmune diseases such as SLE.

Primary antifungal prophylaxis: decrease of invasive fungal disease incidence and reduction of risk factors in haematological patients in a 5-year retrospective study.

BACKGROUND: Invasive fungal disease (IFD) is a major cause of morbidity and mortality in patients with haematological malignancies. AIM: To evaluate the efficacy and rationality of primary antifungal prophylaxis (PAP) in a 5-year real-life setting and choose an appropriate PAP strategy. METHODS: Clinical data of patients were retrospectively reviewed and IFD was diagnosed using the revised diagnostic criteria. The efficacy of PAP and the risk factors for IFD, especially the rationality of PAP, were evaluated. RESULTS: Of the 1340 patients enrolled, 749 patients received PAP (55.9%), and IFD occurred in 157 patients: 51 (6.8%) in the PAP group and 106 (17.9%) in the non-PAP group (P = 0.000). The IFD-related mortality was 10.1 and 29.7% in the PAP group and non-PAP group (P = 0.000) respectively. PAP was an independent protective factor for IFD (odds ratio = 0.183, 95% confidence interval: 0.122-0.274, P = 0.000) and could reduce the effect of risk factors, such as allogeneic haemopoietic stem cell transplantation, prolonged neutropenia and corticosteroid. The IFD incidence was not significantly different among different PAP regimens and PAP start time subgroups, and it was lowest (4.2%) when PAP started after a short period of neutropenia (1-10 days). CONCLUSION: PAP is necessary and efficient to prevent IFD in haematological patients, and the real-life PAP strategy is reasonable. Different drugs can be chosen, and it is better to start PAP as soon as neutropenia begins.

CARD9-Dependent Neutrophil Recruitment Protects against Fungal Invasion of the Central Nervous System.

Candida is the most common human fungal pathogen and causes systemic infections that require neutrophils for effective host defense. Humans deficient in the C-type lectin pathway adaptor protein CARD9 develop spontaneous fungal disease that targets the central nervous system (CNS). However, how CARD9 promotes protective antifungal immunity in the CNS remains unclear. Here, we show that a patient with CARD9 deficiency had impaired neutrophil accumulation and induction of neutrophil-recruiting CXC chemokines in the cerebrospinal fluid despite uncontrolled CNS Candida infection. We phenocopied the human susceptibility in Card9-/- mice, which develop uncontrolled brain candidiasis with diminished neutrophil accumulation. The induction of neutrophil-recruiting CXC chemokines is significantly impaired in infected Card9-/- brains, from both myeloid and resident glial cellular sources, whereas cell-intrinsic neutrophil chemotaxis is Card9-independent. Taken together, our data highlight the critical role of CARD9-dependent neutrophil trafficking into the CNS and provide novel insight into the CNS fungal susceptibility of CARD9-deficient humans.

[Tissue distribution of araloside A in rats].

Araloside A is one of the main active ingredients of Aralia taibaiensis. In this study, HPLC-MS/MS analysis method of araloside A in the main organs of SD rats was established. At the same time, the content of araloside A in the main organs (heart, liver, spleen, lung, kidney, brain) after oral administration with araloside A (50 mg•kg⁻¹) were determined to explore the tissue distribution characteristics of araloside A in vivo. The results showed that the methodological study of araloside A in the main organs of SD rats met the requirements, araloside A distributed in heart, liver, spleen, lung, kidney and brain tissues reached peak at 1 h or 2 h after oral administration with 50 mg•kg-1.The distributions of araloside A at different time points after administration were distinct as follows： the content of araloside A at 20 min：liver>heart>spleen>lung>kidney>brain; the content of araloside A at 1 h： liver>spleen>kidney>lung>heart>brain; the content of araloside A at 2 h： liver>kidney>heart>spleen>lung>brain; the content of araloside A at 4 h： kidney>liver>spleen>heart>lung>brain; the content of araloside A at 8 h： spleen>heart>liver>kidney>lung>brain. Therefore, araloside A was mainly distributed in liver tissue, which had a certain correlation with the common use of Aralia taibaiensis in the treatment of hepatic disease. In addition, araloside A shows a low content but an obvious distribution in brain tissues, which indicates that the drug can pass through blood-brain barrier, and provides the basis for the study of araloside A in brain tissue.

Novel JAZ co-operativity and unexpected JA dynamics underpin Arabidopsis defence responses to Pseudomonas syringae infection.

Pathogens target phytohormone signalling pathways to promote disease. Plants deploy salicylic acid (SA)-mediated defences against biotrophs. Pathogens antagonize SA immunity by activating jasmonate signalling, for example Pseudomonas syringae pv. tomato DC3000 produces coronatine (COR), a jasmonic acid (JA) mimic. This study found unexpected dynamics between SA, JA and COR and co-operation between JAZ jasmonate repressor proteins during DC3000 infection. We used a systems-based approach involving targeted hormone profiling, high-temporal-resolution micro-array analysis, reverse genetics and mRNA-seq. Unexpectedly, foliar JA did not accumulate until late in the infection process and was higher in leaves challenged with COR-deficient P. syringae or in the more resistant JA receptor mutant coi1. JAZ regulation was complex and COR alone was insufficient to sustainably induce JAZs. JAZs contribute to early basal and subsequent secondary plant defence responses. We showed that JAZ5 and JAZ10 specifically co-operate to restrict COR cytotoxicity and pathogen growth through a complex transcriptional reprogramming that does not involve the basic helix-loop-helix transcription factors MYC2 and related MYC3 and MYC4 previously shown to restrict pathogen growth. mRNA-seq predicts compromised SA signalling in a jaz5/10 mutant and rapid suppression of JA-related components on bacterial infection.

Characterization of a JAZ7 activation-tagged Arabidopsis mutant with increased susceptibility to the fungal pathogen Fusarium oxysporum.

In Arabidopsis, jasmonate (JA)-signaling plays a key role in mediating Fusarium oxysporum disease outcome. However, the roles of JASMONATE ZIM-domain (JAZ) proteins that repress JA-signaling have not been characterized in host resistance or susceptibility to this pathogen. Here, we found most JAZ genes are induced following F. oxysporum challenge, and screening T-DNA insertion lines in Arabidopsis JAZ family members identified a highly disease-susceptible JAZ7 mutant (jaz7-1D). This mutant exhibited constitutive JAZ7 expression and conferred increased JA-sensitivity, suggesting activation of JA-signaling. Unlike jaz7 loss-of-function alleles, jaz7-1D also had enhanced JA-responsive gene expression, altered development and increased susceptibility to the bacterial pathogen PstDC3000 that also disrupts host JA-responses. We also demonstrate that JAZ7 interacts with transcription factors functioning as activators (MYC3, MYC4) or repressors (JAM1) of JA-signaling and contains a functional EAR repressor motif mediating transcriptional repression via the co-repressor TOPLESS (TPL). We propose through direct TPL recruitment, in wild-type plants JAZ7 functions as a repressor within the JA-response network and that in jaz7-1D plants, misregulated ectopic JAZ7 expression hyper-activates JA-signaling in part by disturbing finely-tuned COI1-JAZ-TPL-TF complexes.