Fusarium pseudograminearum is a soilborne, hemibiotrophic phytopathogenic fungus that causes Fusarium crown rot and Fusarium head blight in wheat. The basic leucine zipper proteins (bZIPs) are evolutionarily conserved transcription factors that play crucial roles in a range of growth and developmental processes and the responses to biotic and abiotic stresses. However, the roles of bZIP transcription factors remains unknown in F. pseudograminearum. In this study, a bZIP transcription factor Fpkapc was identified to localize to the nucleus in F. pseudograminearum. A mutant strain (Δfpkapc) was constructed to determine the role of Fpkapc in growth and pathogenicity of F. pseudograminearum. Transcriptomic analyses revealed that many genes involved in basic metabolism and oxidation-reduction processes were downregulated, whereas many genes involved in metal iron binding were upregulated in the Δfpkapc strain, compared with the wild type (WT). Correspondingly, the mutant had severe growth defects and displayed abnormal hyphal tips. Conidiation in the Fpkapc mutant was reduced, with more conidia in smaller size and fewer septa than in the WT. Also, relative to WT, the Δfpkapc strain showed greater tolerance to ion stress, but decreased tolerance to H2O2. The mutant caused smaller disease lesions on wheat and barley plants, but significantly increased TRI gene expression, compared with the WT. In summary, Fpkapc plays multiple roles in governing growth, development, stress responses, and virulence in F. pseudograminearum.
In our previous studies, two polysaccharides (MC-1 and MC-2) were identified in the roots of maca (Lepidium meyenii). In this study, the effects of these two polysaccharides on intestinal immunity and inflammation were assessed using intestinal epithelial cells, i.e., Caco-2 cells. The levels of cytokines and tight junction proteins were measured using ELISA and qPCR, respectively. The results showed that MC-1 and MC-2 were difficult to be absorbed in the Caco-2 cell monolayer, but promoted the secretion of IL-8, IL-10, IL-12, and INF-γ in the Caco-2 cells, and the secretion of TNF-α, IL-6, and NO in macrophages (RAW264.7 cells) via the Caco-2 cell monolayer. Additionally, both polysaccharides inhibited damage induced by lipopolysaccharides to the densification of the Caco-2 monolayer membrane by regulating the expressions of TLR4, ZO-1, and occludin. Furthermore, the secretion of inflammatory factors such as TNF-α, IL-8, and INF-γ was inhibited, and the secretion of the anti-inflammatory factor, IL-10, increased. The results indicated that MC-1 and MC-2 can activate intestinal immunity and alleviate intestinal inflammation in vitro.
Differentially expressed cathepsin and clustered unknown genes in Bemisia tabaci after acquisition of TYLCV or ToCV for 24, 48, and 72Â h, respectively. (XLSX 41 kb)
Abstract Steroid receptor coactivator 3 (SRC-3) is a transcriptional coactivator that interacts with nuclear receptors and some other transcription factors to enhance their effects on target gene transcription. We reported previously that SRC-3–deficient (SRC-3−/−) mice are extremely susceptible to Escherichia coli–induced septic peritonitis as a result of uncontrolled inflammation and a defect in bacterial clearance. In this study, we observed significant upregulation of SRC-3 in colonic epithelial cells in response to Citrobacter rodentium infection. Based on these findings, we hypothesized that SRC-3 is involved in host defense against attaching and effacing bacterial infection. We compared the responses of SRC-3−/− and wild-type mice to intestinal C. rodentium infection. We found that SRC-3−/− mice exhibited delayed clearance of C. rodentium and more severe tissue pathology after oral infection with C. rodentium compared with wild-type mice. SRC-3−/− mice expressed normal antimicrobial peptides in the colons but exhibited delayed recruitment of neutrophils into the colonic mucosa. Accordingly, SRC-3−/− mice showed a delayed induction of CXCL2 and CXCL5 in colonic epithelial cells, which are responsible for neutrophil recruitment. At the molecular level, we found that SRC-3 can activate the NF-κB signaling pathway to promote CXCL2 expression at the transcriptional level. Collectively, we show that SRC-3 contributes to host defense against enteric bacteria, at least in part via upregulating CXCL2 expression to recruit neutrophils.
Pien Tze Huang (PZH), a Class I nationally protected Traditional Chinese Medicine (TCM), has been used to treat liver diseases such as hepatitis; however, the effect of PZH on the progression of sepsis is unknown. Here, we reported that PZH attenuated lipopolysaccharide (LPS)-induced sepsis in mice and reduced LPS-induced production of proinflammatory cytokines in macrophages by inhibiting the activation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signalling. Mechanistically, PZH stimulated signal transducer and activator of transcription 3 (STAT3) phosphorylation to induce the expression of A20, which could inhibit the activation of NF-κB and MAPK signalling. Knockdown of the bile acid (BA) receptor G protein-coupled bile acid receptor 1 (TGR5) in macrophages abolished the effects of PZH on STAT3 phosphorylation and A20 induction, as well as the LPS-induced inflammatory response, suggesting that BAs in PZH may mediate its anti-inflammatory effects by activating TGR5. Consistently, deprivation of BAs in PZH by cholestyramine resin reduced the effects of PZH on the expression of phosphorylated-STAT3 and A20, the activation of NF-κB and MAPK signalling, and the production of proinflammatory cytokines, whereas the addition of BAs to cholestyramine resin-treated PZH partially restored the inhibitory effects on the production of proinflammatory cytokines. Overall, our study identifies BAs as the effective components in PZH that activate TGR5-STAT3-A20 signalling to ameliorate LPS-induced sepsis.
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