224 research outputs found

    The Arabidopsis Malectin-Like/LRR-RLK IOS1 is Critical for BAK1-Dependent and BAK1-Independent Pattern-Triggered Immunity

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    Plasma membrane-localized pattern recognition receptors (PRRs) such as FLAGELLIN SENSING2 (FLS2), EF-TU RECEPTOR (EFR) and CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) recognize microbe-associated molecular patterns (MAMPs) to activate pattern-triggered immunity (PTI). A reverse genetics approach on genes responsive to the priming agent beta-aminobutyric acid (BABA) revealed IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) as a critical PTI player. Arabidopsis thaliana ios1 mutants were hyper-susceptible to Pseudomonas syringae bacteria. Accordingly, ios1 mutants showed defective PTI responses, notably delayed up-regulation of the PTI-marker gene FLG22-INDUCED RECEPTOR-LIKE KINASE1 (FRK1), reduced callose deposition and mitogen-activated protein kinase activation upon MAMP treatment. Moreover, Arabidopsis lines over-expressing IOS1 were more resistant to bacteria and showed a primed PTI response. In vitro pull-down, bimolecular fluorescence complementation, co-immunoprecipitation, and mass spectrometry analyses supported the existence of complexes between the membrane-localized IOS1 and BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1)-dependent PRRs FLS2 and EFR, as well as with the BAK1-independent PRR CERK1. IOS1 also associated with BAK1 in a ligand-independent manner, and positively regulated FLS2-BAK1 complex formation upon MAMP treatment. In addition, IOS1 was critical for chitin-mediated PTI. Finally, ios1 mutants were defective in BABA-induced resistance and priming. This work reveals IOS1 as a novel regulatory protein of FLS2-, EFR- and CERK1-mediated signaling pathways that primes PTI activation

    Dynamics of HBV cccDNA expression and transcription in different cell growth phase

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    <p>Abstract</p> <p>Background</p> <p>The covalently closed-circular DNA (cccDNA) of hepatitis B virus (HBV) is associated with viral persistence in HBV-infected hepatocytes. However, the regulation of cccDNA and its transcription in the host cells at different growth stages is not well understood.</p> <p>Methods</p> <p>We took advantages of a stably HBV-producing cell line, 1.3ES2, and examine the dynamic changes of HBV cccDNA, viral transcripts, and viral replication intermediates in different cellular growth stages.</p> <p>Results</p> <p>In this study, we showed that cccDNA increased suddenly in the initial proliferation phase of cell growth, probably attributable to its nuclear replenishment by intracellular nucleocapsids. The amount of cccDNA then decreased dramatically in the cells during their exponential proliferation similar to the loss of extrachromosomal plasmid DNA during cell division, after which it accumulated gradually while the host cells grew to confluency. We found that cccDNA was reduced in dividing cells and could be removed when proliferating cells were subjected to long term of lamivudine (3TC) treatment. The amounts of viral replicative intermediates were rapidly reduced in these proliferating cells and were significantly increased after cells reaching confluency. The expression levels of viral transcripts were increased in parallel with the elevated expression of hepatic transcription factors (HNF4α, CEBPα, PPARα, etc.) during cell growth confluency. The HBV transcripts were transcribed from both integrated viral genome and cccDNA, however the transcriptional abilities of cccDNA was less efficient then that from integrated viral genome in all cell growth stages. We also noted increases in the accumulation of intracellular viral particles and the secretion of mature virions as the cells reached confluency and ceased to grow.</p> <p>Conclusions</p> <p>Based on the dynamics of HBV replication, we propose that HBV replication is modulated differently in the different stages of cell growth, and can be divided into three phases (initial proliferation phase, exponential proliferation phase and growth confluency phase) according to the cell growth curve. The regulation of cccDNA in different cell growth phase and its importance regarding HBV replication are discussed.</p

    Expression of PRDX6 Correlates with Migration and Invasiveness of Colorectal Cancer Cells

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    Background/Aims: Colorectal cancer (CRC) is the third most common type of cancer and the second leading cause of cancer-related deaths worldwide. PRDXs are antioxidant enzymes that play an important role in cell differentiation, proliferation and apoptosis and have diverse functions in malignancy development. However, the mechanism of aberrant overexpression of PRDX6 in CRC remains unclear. Methods: Boyden chamber assay, flow cytometry and a lentiviral shRNA targeting PRDX6 and transient transfection with pCMV-6-PRDX6 plasmid were used to examine the role of PRDX6 in the proliferation capacity and invasiveness of CRC cells. Immunohistochemistry (IHC) with tissue array containing 40 paraffin- embedded CRC tissue specimens and Western blot assays were used to detect target proteins. Results: PRDX6 was significantly up-expressed in different comparisons of metastasis of colorectal adenomas in node-positive CRC (P = 0.03). In in vitro HCT-116, PRDX6 silencing markedly suppressed CRC cell migration and invasiveness while also inducing cell cycle arrest as well as the generation of reactive oxygen species (ROS); specific overexpression of PRDX6 had the opposite effect. Mechanistically, the PRDX6 inactivation displayed decreased levels of PRDX6, N-cadherin, β-catenin, Vimentin, Slug, Snail and Twist-1 through the activation of the PI3K/ AKT/p38/p50 pathways, but they were also significantly inhibited by PRDX6 transfectants. There was also increased transcriptional activation of dimethylation of histone H3 lysine 4 (H3K4me3) of PRDX6 promoter via the activation of the PI3K/Akt/NFkB pathways. Conclusion: Our findings demonstrated that PRDX6 expression plays a characteristic growth-promoting role in CRC metastasis. This study suggests that PRDX6 may serve as a biomarker of node-positive status and may have a role as an important endogenous regulator of cancer cell tumorigenicity in CRC. PRDX6 may also be an effective therapeutic target

    ITPKC Single Nucleotide Polymorphism Associated with the Kawasaki Disease in a Taiwanese Population

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    Kawasaki disease (KD) is characterized by systemic vasculitis with unknown etiology. Previous studies from Japan indicated that a gene polymorphism of ITPKC (rs28493229) is responsible for susceptibility to KD. We collected DNA samples from 1,531 Taiwanese subjects (341 KD patients and 1,190 controls) for genotyping ITPKC. In this study, no significant association was noted for the ITPKC polymorphism (rs28493229) between the controls and KD patients, although the CC genotype was overrepresented. We further combined our data with previously published case/control KD studies in the Taiwanese population and performed a meta-analysis. A significant association between rs28493229 and KD was found (Odds Ratio:1.36, 95% Confidence Interval 1.12–1.66). Importantly, a significant association was obtained between rs28493229 and KD patients with aneurysm formation (P = 0.001, under the recessive model). Taken together, our results indicated that C-allele of ITPKC SNP rs28493229 is associated with the susceptibility and aneurysm formation in KD patients in a Taiwanese population

    The effectiveness of psychosocial and behavioral interventions for informal dementia caregivers:Meta-analyses and meta-regressions

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    Background:  Many psychosocial and behavioral interventions have been developed for informal dementia caregivers. Because existing meta-analyses only focused on a limited number of interventions and outcomes, how effective these interventions are overall and which interventions components are associated with larger effects has yet to be explored. Objective:  To provide a comprehensive meta-analysis of the effectiveness of psychosocial and behavioral interventions on burden, depression, anxiety, quality of life, stress, and sense of competence in informal dementia caregivers. In addition, we examined if interventions which utilized more sessions and/or were delivered personally (face-to-face) had larger effect sizes. In exploratory meta-regressions, we examined seven additional moderators. Methods:  The protocol was registered with PROSPERO, number CRD42017062555. We systematically searched the literature to identify controlled trials assessing the effect of psychosocial and behavioral interventions on the six outcome measures, for informal dementia caregivers. We performed six random effects meta-analyses, to assess the pooled effect sizes of the interventions. In addition, we performed separate meta-regressions, for each outcome, for each moderator. Results:  The sample consisted of 60 studies. For all outcomes except anxiety, the pooled effects were small and in favor of the intervention group. No moderator was found to systematically predict these effects. There were no indications for publication bias or selection bias based on significance. Conclusion:  Overall, the interventions yield significant (small) effects, independent of intervention characteristics. Future research should explore options to enhance the effectiveness of interventions aimed at assisting informal caregivers

    Isolation of Bacteria Capable of Degrading Various AHLs for Biofouling Control in Membrane Bioreactors

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    Membrane bioreactors (MBRs) are widely used to treat wastewater, mainly due to the production of high-quality effluent. However, biofilm forming on the surface of membranes can cause many problems, which remains one of the major limitations of this technique. Bacterial quorum quenching (QQ) has been proven to be a successful strategy to control biofouling in MBRs. However, for many QQ bacterial isolates, the detailed degradation rates of acyl homoserine lactones (AHLs) have rarely been reported. Therefore, this study aimed to isolate potential QQ bacteria and investigate their degradation rates against eight different AHLs. Results showed that four isolates (A9, A12, B11, and D3) exhibited consistent C8-HSL&ndash;(N-octanoyl-L-homoserine lactone) removal capabilities. These four isolates removed at least 70% of all AHLs tested within 180 min. They might have different QQ enzymes, based on our observation that the locations of enzyme activities differed. The bacteria most closely related to A9, A12, and B11 were Brucella anthropic, Bacillus cereus, and Bacillus toyonensis, respectively. Bacillus species have shown QQ activity in many studies, but AHL-reducing Brucella species have not been previously reported. Overall, this study extends our current knowledge of QQ bacteria that could be used to mitigate biofilm formation on MBR membranes
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