Berberine (BBR), an alkaloid isolated from Rhizoma Coptidis, Cortex Phellode, and Berberis, has been widely used in the treatment of ulcerative colitis (UC). However, the mechanism of BBR on UC is unknown. In this study, we investigated the activities of T regulatory cell (Treg) and T helper 17 cell (Th17) in a dextran sulfate sodium (DSS)-induced UC mouse model after BBR administration. We also investigated the changes of gut microbiota composition using 16S rRNA analysis. We also examined whether BBR could regulate the Treg/Th17 balance by modifying gut microbiota. The mechanism was further confirmed by depleting gut microbiota through a combination of antibiotic treatment and fecal transplantations. Results showed that BBR treatment could improve the Treg/Th17 balance in the DSS-induced UC model. BBR also reduced diversity of the gut microbiota and interfered with the relative abundance of Desulfovibrio, Eubacterium, and Bacteroides. Moreover, BBR treatment did not influence the Treg/Th17 balance after the depletion of gut microbiota. Our results also revealed that fecal transplantation from BBR-treated mice could relieve UC and regulate the Treg/Th17 balance. In conclusion, our study provides evidence that BBR prevents UC by modifying gut microbiota and regulating the balance of Treg/Th17.

WRKY transcription factors constitute a very large family of proteins in plants and participate in modulating plant biological processes, such as growth, development and stress responses. However, the exact roles of WRKY proteins are unclear, particularly in non-model plants. In this study, Gossypium hirsutum WRKY41 (GhWRKY41) was isolated and transformed into Nicotiana benthamiana. Our results showed that overexpression of GhWRKY41 enhanced the drought and salt stress tolerance of transgenic Nicotiana benthamiana. The transgenic plants exhibited lower malondialdehyde content and higher antioxidant enzyme activity, and the expression of antioxidant genes was upregulated in transgenic plants exposed to osmotic stress. A β-glucuronidase (GUS) staining assay showed that GhWRKY41 was highly expressed in the stomata when plants were exposed to osmotic stress, and plants overexpressing GhWRKY41 exhibited enhanced stomatal closure when they were exposed to osmotic stress. Taken together, our findings demonstrate that GhWRKY41 may enhance plant tolerance to stress by functioning as a positive regulator of stoma closure and by regulating reactive oxygen species (ROS) scavenging and the expression of antioxidant genes.

Mitogen-activated protein kinase kinases (MAPKK) mediate a variety of stress responses in plants. So far little is known on the functional role of MAPKKs in cotton. In the present study, Gossypium hirsutum MKK1 (GhMKK1) function was investigated. GhMKK1 protein may activate its specific targets in both the nucleus and cytoplasm. Treatments with salt, drought, and H2O2 induced the expression of GhMKK1 and increased the activity of GhMKK1, while overexpression of GhMKK1 in Nicotiana benthamiana enhanced its tolerance to salt and drought stresses as determined by many physiological data. Additionally, GhMKK1 activity was found to up-regulate pathogen-associated biotic stress, and overexpression of GhMKK1 increased the susceptibility of the transgenic plants to the pathogen Ralstonia solanacearum by reducing the expression of PR genes. Moreover, GhMKK1-overexpressing plants also exhibited an enhanced reactive oxygen species scavenging capability and markedly elevated activities of several antioxidant enzymes. These results indicate that GhMKK1 is involved in plants defence responses and provide new data to further analyze the function of plant MAPK pathways.

WRKY transcription factors form one of the largest transcription factor families and function as important components in the complex signaling processes that occur during plant stress responses. However, relative to the research progress in model plants, far less information is available on the function of WRKY proteins in cotton. In the present study, we identified the GhWRKY40 gene in cotton (Gossypium hirsutum) and determined that the GhWRKY40 protein is targeted to the nucleus and is a stress-inducible transcription factor. The GhWRKY40 transcript level was increased upon wounding and infection with the bacterial pathogen Ralstonia solanacearum. The overexpression of GhWRKY40 down-regulated most of the defense-related genes, enhanced the wounding tolerance and increased the susceptibility to R. solanacearum. Consistent with a role in multiple stress responses, we found that the GhWRKY40 transcript level was increased by the stress hormones salicylic acid (SA), methyl jasmonate (MeJA) and ethylene (ET). Moreover, GhWRKY40 interacted with the MAPK kinase GhMPK20, as shown using yeast two-hybrid and bimolecular fluorescence complementation systems. Collectively, these results suggest that GhWRKY40 is regulated by SA, MeJA and ET signaling and coordinates responses to wounding and R. solanacearum attack. These findings highlight the importance of WRKYs in regulating wounding- and pathogen-induced responses.

Rakicidin A is a cyclic depsipeptide that has exhibited unique growth inhibitory activity against chronic myelogenous leukemia stem cells. Furthermore, rakicidin A has five chiral centers with unknown stereochemical assignment, and thus, can be represented by one of 32 possible stereoisomers. To predict the most probable stereochemistry of rakicidin A, calculations and structural comparison with natural cyclic depsipeptides were applied. A total synthesis of the proposed structure was subsequently completed and highlighted by the creation of a sterically hindered ester bond (C1-C15) through trans-acylation from an easily established isomer (C1-C13). The analytic data of the synthetic target were consistent with that of natural rakicidin A, and then the absolute configuration of rakicidin A was assigned as 2S, 3S, 14S, 15S, 16R. This work suggests strategies for the determination of unknown chiral centers in other cyclic depsipeptides, such as rakicidin B, C, D, BE-43547, and vinylamycin, and facilitates the investigations of rakicidin A as an anticancer stem cell agent.

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Mitogen-activated protein kinase (MAPK) cascades play important roles in the perception of external signals and the generation of suitable responses. Cotton (Gossypium hirsutum) is an important fibre-producing and oil-producing crop worldwide. However, few MAPKs and their interaction partners have been functionally characterized in cotton. In the present study, the group A MAPK G. hirsutum (Gh)MPK6a was identified and characterized. GhMPK6a expression can be induced through multiple defence-related signal molecules and abiotic and biotic stresses. The ectopic expression of GhMPK6a in Nicotiana benthamiana reduced drought and salt tolerance, with elevated malondialdehyde content, higher reactive oxygen species content and lower abscisic acid content than in wild-type plants. Moreover, plants overexpressing GhMPK6a were sensitive to the bacterial pathogen Ralstonia solanacearum. Histochemical analysis of b-glucuronidase activity revealed that GhMPK6a showed tissue-specific expression during postgermination development, mixed bud differentiation, and pollination. Most importantly, GhMPK6a interacts with the upstream MAPK kinase GhMKK4, as shown by the use of yeast two-hybrid and bimolecular fluorescence complementation systems, compensating for a deficiency of MAPK interaction partners in cotton crops. Taken together, these results suggest that GhMPK6a negatively regulates osmotic stress and bacterial infection, and plays an important role in developmental processes. These results provide useful information for elucidating the roles of MAPK cascades in cotton crops. Structured digital abstractGhMPK6a physically interacts with GhMPK4 by two hybrid (View interaction) GhMPK6a and GhMPK4 physically interact by bimolecular fluorescence complementation (View interaction)

BackgroundChinese licorice, (Glycyrrhiza uralensis Fisch.) is one of the commonly prescribed herbs in Traditional Chinese Medicine (TCM). Gancao, as commonly known in China, is associated with immune-modulating and anti-tumor potential though the mechanism of action is not well known. In this study, we investigated the in vitro immunomodulatory and antitumor potential of Glycyrrhiza uralensis polysaccharides fractions of high molecular weight (fraction A), low molecular weight (fraction B) and crude extract (fraction C).MethodsCell proliferation and cytotoxicity was investigated using Cell Counting kit 8 (CCK-8) on Intestinal epithelial cell line (IEC-6) and Colon carcinoma cell line (CT-26). IL-7 gene expression relative to GAPDH was analysed using Real time PCR. The stimulation and viability of T lymphocytes was determined by Trypan blue exclusion assay.ResultsG.uralensis polysaccharides did not inhibit proliferation of IEC-6 cells even at high concentration. The ED50 was found to be 100 μg/ml. On the other hand, the polysaccharides inhibited the proliferation of cancer cells (CT-26) at a concentration of ≤50 μg/ml. Within 72 h of treatment with the polysaccharides, expression of IL-7 gene was up-regulated over 2 times. It was also noted that, IEC-6 cells secrete IL-7 cytokine into media when treated with G.uralensis polysaccharides. The secreted IL-7 stimulated proliferation of freshly isolated T lymphocytes within 6 h. The effect of the polysaccharides were found to be molecular weight depended, with low molecular weight having a profound effect compared to high molecular weight and total crude extract.ConclusionOur findings indicate that G.uralensis polysaccharides especially those of low molecular weight have a potential as anticancer agents. Of great importance, is the ability of the polysaccharides to up-regulate anticancer cytokine IL-7, which is important in proliferation and maturation of immune cells and it is associated with better prognosis in cancer. Therefore, immunomodulation is a possible mode of action of the polysaccharides in cancer therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1171-4) contains supplementary material, which is available to authorized users.