scholarly journals Acidovorax citrulli Type III Effector AopP Suppresses Plant Immunity by Targeting the Watermelon Transcription Factor WRKY6

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiaoxiao Zhang ◽  
Yuwen Yang ◽  
Mei Zhao ◽  
Linlin Yang ◽  
Jie Jiang ◽  
...  

Acidovorax citrulli (Ac) is the causal agent of bacterial fruit blotch (BFB), and BFB poses a threat to global watermelon production. Despite its economic importance, the molecular mechanisms underlying Ac pathogenicity and virulence are not well understood, particularly with regard to its type III secreted effectors. We identify a new effector, AopP, in Ac and confirm its secretion and translocation. AopP suppresses reactive oxygen species burst and salicylic acid (SA) content and significantly contributes to virulence. Interestingly, AopP interacts with a watermelon transcription factor, ClWRKY6, in vivo and in vitro. ClWRKY6 shows typical nuclear localization, and AopP and ClWRKY6 co-localize in the nucleus. Ac infection, SA, and the pathogen-associated molecular pattern flg22Ac promote ClWRKY6 production, suggesting that ClWRKY6 is involved in plant immunity and SA signaling. Furthermore, ClWRKY6 positively regulates PTI and SA production when expressed in Nicotiana benthamiana. Importantly, AopP reduces ClWRKY6 mRNA and ClWRKY6 protein levels, suggesting that AopP suppresses plant immunity by targeting ClWRKY6. In summary, we identify a novel effector associated with the virulence mechanism of Ac, which interacts with the transcription factor of the natural host, watermelon. The findings of this study provide insights into the mechanisms of watermelon immune responses and may facilitate molecular breeding for bacterial fruit blotch resistance.

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1523
Author(s):  
Isabelle Anna Zink ◽  
Erika Wimmer ◽  
Christa Schleper

Prokaryotes are constantly coping with attacks by viruses in their natural environments and therefore have evolved an impressive array of defense systems. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is an adaptive immune system found in the majority of archaea and about half of bacteria which stores pieces of infecting viral DNA as spacers in genomic CRISPR arrays to reuse them for specific virus destruction upon a second wave of infection. In detail, small CRISPR RNAs (crRNAs) are transcribed from CRISPR arrays and incorporated into type-specific CRISPR effector complexes which further degrade foreign nucleic acids complementary to the crRNA. This review gives an overview of CRISPR immunity to newcomers in the field and an update on CRISPR literature in archaea by comparing the functional mechanisms and abundances of the diverse CRISPR types. A bigger fraction is dedicated to the versatile and prevalent CRISPR type III systems, as tremendous progress has been made recently using archaeal models in discerning the controlled molecular mechanisms of their unique tripartite mode of action including RNA interference, DNA interference and the unique cyclic-oligoadenylate signaling that induces promiscuous RNA shredding by CARF-domain ribonucleases. The second half of the review spotlights CRISPR in archaea outlining seminal in vivo and in vitro studies in model organisms of the euryarchaeal and crenarchaeal phyla, including the application of CRISPR-Cas for genome editing and gene silencing. In the last section, a special focus is laid on members of the crenarchaeal hyperthermophilic order Sulfolobales by presenting a thorough comparative analysis about the distribution and abundance of CRISPR-Cas systems, including arrays and spacers as well as CRISPR-accessory proteins in all 53 genomes available to date. Interestingly, we find that CRISPR type III and the DNA-degrading CRISPR type I complexes co-exist in more than two thirds of these genomes. Furthermore, we identified ring nuclease candidates in all but two genomes and found that they generally co-exist with the above-mentioned CARF domain ribonucleases Csx1/Csm6. These observations, together with published literature allowed us to draft a working model of how CRISPR-Cas systems and accessory proteins cross talk to establish native CRISPR anti-virus immunity in a Sulfolobales cell.


Blood ◽  
2012 ◽  
Vol 119 (18) ◽  
pp. 4174-4181 ◽  
Author(s):  
Hai Vu Nguyen ◽  
Enguerran Mouly ◽  
Karine Chemin ◽  
Romain Luinaud ◽  
Raymonde Despres ◽  
...  

Abstract In response to antigens and cytokines, mouse B cells undergo class-switch recombination (CSR) and differentiate into Ig-secreting cells. T-bet, a T-box transcription factor that is up-regulated in lymphocytes by IFN-γ or IL-27, was shown to regulate CSR to IgG2a after T cell–independent B-cell stimulations. However, the molecular mechanisms controlling this process remain unclear. In the present study, we show that inactivation of the Ets-1 transcription factor results in a severe decrease in IgG2a secretion in vivo and in vitro. No T-bet expression was observed in Ets-1–deficient (Ets-1−/−) B cells stimulated with IFN-γ and lipopolysaccharide, and forced expression of T-bet in these cells rescued IgG2a secretion. Furthermore, we identified a transcriptional enhancer in the T-bet locus with an activity in B cells that relies on ETS-binding sites. After IFN-γ stimulation of Ets-1−/− B cells, activated Stat1, which forms a complex with Ets-1 in wild-type cells, no longer binds to the T-bet enhancer or promotes histone modifications at this site. These results demonstrate that Ets-1 is critical for IgG2a CSR and acts as an essential cofactor for Stat1 in the regulation of T-bet expression in B cells.


2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Chaohui Gu ◽  
Keyuan Zhao ◽  
Naichun Zhou ◽  
Feng Liu ◽  
Fei Xie ◽  
...  

Abstract Emerging evidences have demonstrated that ubiquitin-associated domain-containing protein 2 (UBAC2) is closely related to the occurrence and development of malignant tumors. However, the functions and underlying molecular mechanisms of UBAC2 in bladder cancer (BC) development have not been defined. In this study, we found that both UBAC2 mRNA and protein levels were upregulated in BC tissues and cell lines, and knockdown of UBAC2 inhibited BC cells proliferation both in vitro and in vivo. Meanwhile, Kaplan–Meier survival plots of 406 BC cases from TCGA database showed that higher expression of UBAC2 in BC patients was associated with lower survival rate. Mechanistic studies revealed that knockdown of UBAC2 increased the expression of p27 by posttranscriptional regulation. Our previous study indicated that circular RNA BCRC-3 (BCRC-3) promoted the expression of p27 through interacting with miR-182-5p, and reversed miR-182-5p-induced inhibition of p27 3′UTR activity. In the present study, we found that UBAC2 could bind to BCRC-3, and subsequently affected the interaction of BCRC-3 with miR-182-5p to inhibit the expression of p27. Furthermore, knockdown of BCRC-3 partly reversed the upregulation of p27 expression induced by knockdown of UBAC2. Our findings highlight a novel mechanism of UBAC2 in regulating p27 through affecting the function of BCRC-3, and provide a research basis for the diagnostic and therapeutic application of BC.


2010 ◽  
Vol 107 (5) ◽  
pp. 2349-2354 ◽  
Author(s):  
Mike Wilton ◽  
Rajagopal Subramaniam ◽  
James Elmore ◽  
Corinna Felsensteiner ◽  
Gitta Coaker ◽  
...  

Plant immunity can be induced by two major classes of pathogen-associated molecules. Pathogen- or microbe-associated molecular patterns (PAMPs or MAMPs) are conserved molecular components of microbes that serve as “non-self” features to induce PAMP-triggered immunity (PTI). Pathogen effector proteins used to promote virulence can also be recognized as “non-self” features or induce a “modified-self” state that can induce effector-triggered immunity (ETI). The Arabidopsis protein RIN4 plays an important role in both branches of plant immunity. Three unrelated type III secretion effector (TTSE) proteins from the phytopathogen Pseudomonas syringae, AvrRpm1, AvrRpt2, and AvrB, target RIN4, resulting in ETI that effectively restricts pathogen growth. However, no pathogenic advantage has been demonstrated for RIN4 manipulation by these TTSEs. Here, we show that the TTSE HopF2Pto also targets Arabidopsis RIN4. Transgenic plants conditionally expressing HopF2Pto were compromised for AvrRpt2-induced RIN4 modification and associated ETI. HopF2Pto interfered with AvrRpt2-induced RIN4 modification in vitro but not with AvrRpt2 activation, suggestive of RIN4 targeting by HopF2Pto. In support of this hypothesis, HopF2Pto interacted with RIN4 in vitro and in vivo. Unlike AvrRpm1, AvrRpt2, and AvrB, HopF2Pto did not induce ETI and instead promoted P. syringae growth in Arabidopsis. This virulence activity was not observed in plants genetically lacking RIN4. These data provide evidence that RIN4 is a major virulence target of HopF2Pto and that a pathogenic advantage can be conveyed by TTSEs that target RIN4.


Blood ◽  
2008 ◽  
Vol 111 (8) ◽  
pp. 4081-4091 ◽  
Author(s):  
Laure Gilles ◽  
Romain Guièze ◽  
Dominique Bluteau ◽  
Véronique Cordette-Lagarde ◽  
Catherine Lacout ◽  
...  

Abstract The molecular mechanisms that regulate megakaryocyte (MK) ploidization are poorly understood. Using MK differentiation from primary human CD34+ cells, we observed that p19INK4D expression was increased both at the mRNA and protein levels during ploidization. p19INK4D knockdown led to a moderate increase (31.7% ± 5%) in the mean ploidy of MKs suggesting a role of p19INK4D in the endomitotic arrest. This increase in ploidy was associated with a decrease in the more mature MK population (CD41highCD42high) at day 9 of culture, which was related to a delay in differentiation. Inversely, p19INK4D overexpression in CD34+ cells resulted in a decrease in mean ploidy level associated with an increase in CD41 and CD42 expression in each ploidy class. Confirming these in vitro results, bone marrow MKs from p19INK4D KO mice exhibited an increase in mean ploidy level from 18.7N (± 0.58N) to 52.7N (± 12.3N). Chromatin immunoprecipitation assays performed in human MKs revealed that AML-1 binds in vivo the p19INK4D promoter. Moreover, AML-1 inhibition led to the p19INK4D down-regulation in human MKs. These results may explain the molecular link at the transcriptional level between the arrest of endomitosis and the acceleration of MK differentiation.


Diabetologia ◽  
2021 ◽  
Author(s):  
Maude Giroud ◽  
Foivos-Filippos Tsokanos ◽  
Giorgio Caratti ◽  
Stefan Kotschi ◽  
Sajjad Khani ◽  
...  

Abstract Aims/hypothesis Adipocytes are critical cornerstones of energy metabolism. While obesity-induced adipocyte dysfunction is associated with insulin resistance and systemic metabolic disturbances, adipogenesis, the formation of new adipocytes and healthy adipose tissue expansion are associated with metabolic benefits. Understanding the molecular mechanisms governing adipogenesis is of great clinical potential to efficiently restore metabolic health in obesity. Here we investigate the role of heart and neural crest derivatives-expressed 2 (HAND2) in adipogenesis. Methods Human white adipose tissue (WAT) was collected from two cross-sectional studies of 318 and 96 individuals. In vitro, for mechanistic experiments we used primary adipocytes from humans and mice as well as human multipotent adipose-derived stem (hMADS) cells. Gene silencing was performed using siRNA or genetic inactivation in primary adipocytes from loxP and or tamoxifen-inducible Cre-ERT2 mouse models with Cre-encoding mRNA or tamoxifen, respectively. Adipogenesis and adipocyte metabolism were measured by Oil Red O staining, quantitative PCR (qPCR), microarray, glucose uptake assay, western blot and lipolysis assay. A combinatorial RNA sequencing (RNAseq) and ChIP qPCR approach was used to identify target genes regulated by HAND2. In vivo, we created a conditional adipocyte Hand2 deletion mouse model using Cre under control of the Adipoq promoter (Hand2AdipoqCre) and performed a large panel of metabolic tests. Results We found that HAND2 is an obesity-linked white adipocyte transcription factor regulated by glucocorticoids that was necessary but insufficient for adipocyte differentiation in vitro. In a large cohort of humans, WAT HAND2 expression was correlated to BMI. The HAND2 gene was enriched in white adipocytes compared with brown, induced early in differentiation and responded to dexamethasone (DEX), a typical glucocorticoid receptor (GR, encoded by NR3C1) agonist. Silencing of NR3C1 in hMADS cells or deletion of GR in a transgenic conditional mouse model results in diminished HAND2 expression, establishing that adipocyte HAND2 is regulated by glucocorticoids via GR in vitro and in vivo. Furthermore, we identified gene clusters indirectly regulated by the GR–HAND2 pathway. Interestingly, silencing of HAND2 impaired adipocyte differentiation in hMADS and primary mouse adipocytes. However, a conditional adipocyte Hand2 deletion mouse model using Cre under control of the Adipoq promoter did not mirror these effects on adipose tissue differentiation, indicating that HAND2 was required at stages prior to Adipoq expression. Conclusions/interpretation In summary, our study identifies HAND2 as a novel obesity-linked adipocyte transcription factor, highlighting new mechanisms of GR-dependent adipogenesis in humans and mice. Data availability Array data have been submitted to the GEO database at NCBI (GSE148699). Graphical abstract


Author(s):  
Moritz von Scheidt ◽  
Yuqi Zhao ◽  
Thomas Q. de Aguiar Vallim ◽  
Nam Che ◽  
Michael Wierer ◽  
...  

Background: Coronary artery disease (CAD) is a multifactorial condition with both genetic and exogenous causes. The contribution of tissue specific functional networks to the development of atherosclerosis remains largely unclear. The aim of this study was to identify and characterise central regulators and networks leading to atherosclerosis. Methods: Based on several hundred genes known to affect atherosclerosis risk in mouse (as demonstrated in knock-out models) and human (as shown by genome-wide association studies (GWAS)) liver gene regulatory networks were modeled. The hierarchical order and regulatory directions of genes within the network were based on Bayesian prediction models as well as experimental studies including chromatin immunoprecipitation DNA-Sequencing (ChIP-Seq), ChIP mass spectrometry (ChIP-MS), overexpression, siRNA knockdown in mouse and human liver cells, and knockout mouse experiments. Bioinformatics and correlation analyses were used to clarify associations between central genes and CAD phenotypes in both human and mouse. Results: The transcription factor MAFF interacted as a key driver of a liver network with three human genes at CAD GWAS loci and eleven atherosclerotic murine genes. Most importantly, expression levels of the low-density lipoprotein receptor ( LDLR ) gene correlated with MAFF in 600 CAD patients undergoing bypass surgery (STARNET) and a hybrid mouse diversity panel involving 105 different inbred mouse strains. Molecular mechanisms of MAFF were tested under non-inflammatory conditions showing a positive correlation between MAFF and LDLR in vitro and in vivo . Interestingly, after LPS stimulation (inflammatory conditions) an inverse correlation between MAFF and LDLR in vitro and in vivo was observed. ChIP-MS revealed that the human CAD GWAS candidate BACH1 assists MAFF in the presence of LPS stimulation with respective heterodimers binding at the MAF recognition element (MARE) of the LDLR promoter to transcriptionally downregulate LDLR expression. Conclusions: The transcription factor MAFF was identified as a novel central regulator of an atherosclerosis/CAD relevant liver network. MAFF triggered context specific expression of LDLR and other genes known to affect CAD risk. Our results suggest that MAFF is a missing link between inflammation, lipid and lipoprotein metabolism and a possible treatment target.


2020 ◽  
Author(s):  
Zhanwang Wang ◽  
Dong He ◽  
Yuxing Zhu ◽  
Xueying Hu ◽  
Yi Jin ◽  
...  

Abstract Background: Increasing evidence have emphasized the importance of long non-coding RNAs (lncRNAs) in various human cancers progression. Forkhead box D1 antisense RNA1 (FOXD1-AS1) is a novel lncRNA and plays vital regulatory role in diverse biological processes of cancers. However, the biological function, molecular mechanism and clinical significance of FOXD1-AS1 in nasopharyngeal carcinoma is still unknown.Methods: Comprehensive bioinformatics analysis and qRT-PCR was conducted to detect the expression level of FOXD1-AS1. Loss-of-function and gain-of-function experiments were performed to verify the functions of FOXD1-AS1 in proliferation, migration, invasion, apoptosis and glycolysis of nasopharyngeal carcinoma in vitro and in vivo. Further bioinformatics analysis and experiments were carried out to explore the underlying molecular mechanisms of FOXD1-AS1. Results: FOXD1-AS1 was significantly overexpressed in nasopharyngeal carcinoma and associated with poor survival in patients. Knockdown of FOXD1-AS1 significantly inhibited cell proliferation, migration, invasion and glycolysis, and promotes apoptosis in nasopharyngeal carcinoma, whereas over-expression of FOXD1-AS1 has the opposite effect. Mechanistically, we found that FOXD1-AS1 could upregulate the expression of FOXD1 through stabilizing the FOXD1 expression at mRNA and protein levels, and FOXD1 increased the glycolysis level by transcriptionally upregulating the expression of LDHA, PKM and ENO1, thus playing an oncogenic role in nasopharyngeal carcinoma progression. Conclusion: FOXD1-AS1 plays a critical regulatory role in nasopharyngeal carcinoma. The identified FOXD1-AS1/FOXD1 axis may serve as a potential prognostic biomarker and therapeutic target for patients with nasopharyngeal carcinoma.


2020 ◽  
Author(s):  
Encheng Zhang ◽  
Xiao Dong ◽  
Jialiang Shao ◽  
Xingyu Mu ◽  
Siteng Chen ◽  
...  

Abstract Background: Recent studies have reported that MLST8 is upregulated in many malignant tumors. Nevertheless, the underlying molecular mechanisms is still unclear. The aim of this work was to investigate how MLST8 contribute to the development and progression of renal cancer (ccRCC).Methods: To identify molecular mediators of the oncogenic tumor function of MLST8, we analyzed a quantitative mass spectrometry by a previous study and checked the amino acid sequence in MLST8. Immunoprecipitation and Western Blotting were used to analyze the interaction between FBXW7 and MLST8. Transwell assays determined cell migration and invasion. In vivo experiments were performed to verify tumor growth. Immunohistochemistry was used to analyze protein levels in patients’ tumor samples. Results: MLST8 is an oncogenic protein in TCGA database and ccRCC clinical specimens. We also ascertain that MLST8 interacts with FBXW7, which was universally regarded as an E3 ubiquitin ligase. MLST8 can be degraded and ubiquitinated by tumor suppressor FBXW7. FBXW7 recognizes a consensus motif (T/S) PXX (S/T/D/E) of MLST8 and triggers MLST8 degradation via the ubiquitin-proteasome pathway. Strikingly, the activated CDK1 kinase engages in the MLST8 phosphorylation required for FBXW7-mediated degradation. In vitro and vivo assay, we further prove that MLST8 is an essential mediator of FBXW7 inactivation-induced tumor growth, migration, and invasion. Furthermore, MLST8 and FBXW7 protein are negatively correlated in human renal cancer specimens. Conclusions: Our findings suggest that MLST8 is a putative oncogene that functions via interaction with FBXW7, and inhibition MLST8 can be a potential future target in ccRCC treatment.


2012 ◽  
Vol 303 (12) ◽  
pp. G1393-G1401 ◽  
Author(s):  
Varsha Singh ◽  
Geetu Raheja ◽  
Alip Borthakur ◽  
Anoop Kumar ◽  
Ravinder K. Gill ◽  
...  

A major mechanism of electroneutral NaCl absorption in the human ileum and colon involves coupling of Na+/H+ and Cl−/HCO3− exchangers. Disturbances in these mechanisms have been implicated in diarrheal conditions. Probiotics such as Lactobacillus have been indicated to be beneficial in the management of gastrointestinal disorders, including diarrhea. However, the molecular mechanisms underlying antidiarrheal effects of probiotics have not been fully understood. We have previously demonstrated Lactobacillus acidophilus (LA) to stimulate Cl−/HCO3− exchange activity via an increase in the surface levels and expression of the Cl−/HCO3− exchanger DRA in vitro and in vivo. However, the effects of LA on NHE3, the Na+/H+ exchanger involved in the coupled electroneutral NaCl absorption, are not known. Current studies were, therefore, undertaken to investigate the effects of LA on the function and expression of NHE3 and to determine the mechanisms involved. Treatment of Caco2 cells with LA or its conditioned culture supernatant (CS) for 8–24 h resulted in a significant increase in Na+/H+ exchange activity, mRNA, and protein levels of NHE3. LA-CS upregulation of NHE3 function and expression was also observed in SK-CO15 cells, a human colonic adenocarcinoma cell line. Additionally, LA treatment increased NHE3 promoter activity, suggesting involvement of transcriptional mechanisms. In vivo, mice gavaged with live LA showed significant increase in NHE3 mRNA and protein expression in the ileum and colonic regions. In conclusion, LA-induced increase in NHE3 expression may contribute to the upregulation of intestinal electrolyte absorption and might underlie the potential antidiarrheal effects of probiotics.


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