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1

Cell Wall Degrading Enzyme Induced Rice Innate Immune Responses Are Suppressed by the Type 3 Secretion System Effectors XopN, XopQ, XopX and XopZ of Xanthomonas oryzae pv. oryzae  

PubMed Central

Innate immune responses are induced in plants and animals through perception of Damage Associated Molecular Patterns. These immune responses are suppressed by pathogens during infection. A number of studies have focussed on identifying functions of plant pathogenic bacteria that are involved in suppression of Pathogen Associated Molecular Pattern induced immune responses. In comparison, there is very little information on functions used by plant pathogens to suppress Damage Associated Molecular Pattern induced immune responses. Xanthomonasoryzae pv. oryzae, a gram negative bacterial pathogen of rice, secretes hydrolytic enzymes such as LipA (Lipase/Esterase) that damage rice cell walls and induce innate immune responses. Here, we show that Agrobacterium mediated transient transfer of the gene for XopN, a X. oryzae pv. oryzae type 3 secretion (T3S) system effector, results in suppression of rice innate immune responses induced by LipA. A xopN- mutant of X. oryzae pv. oryzae retains the ability to suppress these innate immune responses indicating the presence of other functionally redundant proteins. In transient transfer assays, we have assessed the ability of 15 other X. oryzae pv. oryzae T3S secreted effectors to suppress rice innate immune responses. Amongst these proteins, XopQ, XopX and XopZ are suppressors of LipA induced innate immune responses. A mutation in any one of the xopN, xopQ, xopX or xopZ genes causes partial virulence deficiency while a xopN- xopX- double mutant exhibits a greater virulence deficiency. A xopN- xopQ- xopX- xopZ- quadruple mutant of X. oryzae pv. oryzae induces callose deposition, an innate immune response, similar to a X. oryzae pv. oryzae T3S- mutant in rice leaves. Overall, these results indicate that multiple T3S secreted proteins of X. oryzae pv. oryzae can suppress cell wall damage induced rice innate immune responses. PMID:24086651

Sinha, Dipanwita; Gupta, Mahesh Kumar; Patel, Hitendra Kumar; Ranjan, Ashish; Sonti, Ramesh V.

2013-01-01

2

Tomato TFT1 Is Required for PAMP-Triggered Immunity and Mutations that Prevent T3S Effector XopN from Binding to TFT1 Attenuate Xanthomonas Virulence  

E-print Network

XopN is a type III effector protein from Xanthomonas campestris pathovar vesicatoria that suppresses PAMP-triggered immunity (PTI) in tomato. Previous work reported that XopN interacts with the tomato 14-3-3 isoform TFT1; ...

Aakre, Christopher David

3

Tomato TFT1 Is Required for PAMP-Triggered Immunity and Mutations that Prevent T3S Effector XopN from  

E-print Network

Tomato TFT1 Is Required for PAMP-Triggered Immunity and Mutations that Prevent T3S Effector Xop) in tomato. Previous work reported that XopN interacts with the tomato 14-3-3 isoform TFT1; however, TFT1's and is a XopN virulence target. Virus-induced gene silencing of TFT1 mRNA in tomato leaves resulted

Mudgettt, Mary Beth

4

Xanthomonas oryzae pv. oryzae type III effector XopN targets OsVOZ2 and a putative thiamine synthase as a virulence factor in rice.  

PubMed

Xanthomonasoryzae pv. oryzae (Xoo) is spread systemically through the xylem tissue and causes bacterial blight in rice. We evaluated the roles of Xanthomonas outer proteins (Xop) in the Xoo strain KXO85 in a Japonica-type rice cultivar, Dongjin. Five xop gene knockout mutants (xopQ KXO85 , xopX KXO85 , xopP1 KXO85 , xopP2 KXO85 , and xopN KXO85 ) were generated by EZ-Tn5 mutagenesis, and their virulence was assessed in 3-month-old rice leaves. Among these mutants, the xopN KXO85 mutant appeared to be less virulent than the wild-type KXO85; however, the difference was not statistically significant. In contrast, the xopN KXO85 mutant exhibited significantly less virulence in flag leaves after flowering than the wild-type KXO85. These observations indicate that the roles of Xop in Xoo virulence are dependent on leaf stage. We chose the xopN gene for further characterization because the xopN KXO85 mutant showed the greatest influence on virulence. We confirmed that XopNKXO85 is translocated into rice cells, and its gene expression is positively regulated by HrpX. Two rice proteins, OsVOZ2 and a putative thiamine synthase (OsXNP), were identified as targets of XopNKXO85 by yeast two-hybrid screening. Interactions between XopNKXO85 and OsVOZ2 and OsXNP were further confirmed in planta by bimolecular fluorescence complementation and in vivo pull-down assays. To investigate the roles of OsVOZ2 in interactions between rice and Xoo, we evaluated the virulence of the wild-type KXO85 and xopN KXO85 mutant in the OsVOZ2 mutant line PFG_3A-07565 of Dongjin. The wild-type KXO85 and xopN KXO85 mutant were significantly less virulent in the mutant rice line. These results indicate that XopNKXO85 and OsVOZ2 play important roles both individually and together for Xoo virulence in rice. PMID:24019919

Cheong, Hoon; Kim, Chi-Yeol; Jeon, Jong-Seong; Lee, Byoung-Moo; Sun Moon, Jae; Hwang, Ingyu

2013-01-01

5

Xanthomonas oryzae pv. oryzae Type III Effector XopN Targets OsVOZ2 and a Putative Thiamine Synthase as a Virulence Factor in Rice  

PubMed Central

Xanthomonasoryzae pv. oryzae (Xoo) is spread systemically through the xylem tissue and causes bacterial blight in rice. We evaluated the roles of Xanthomonas outer proteins (Xop) in the Xoo strain KXO85 in a Japonica-type rice cultivar, Dongjin. Five xop gene knockout mutants (xopQKXO85, xopXKXO85, xopP1KXO85, xopP2KXO85, and xopNKXO85) were generated by EZ-Tn5 mutagenesis, and their virulence was assessed in 3-month-old rice leaves. Among these mutants, the xopNKXO85 mutant appeared to be less virulent than the wild-type KXO85; however, the difference was not statistically significant. In contrast, the xopNKXO85 mutant exhibited significantly less virulence in flag leaves after flowering than the wild-type KXO85. These observations indicate that the roles of Xop in Xoo virulence are dependent on leaf stage. We chose the xopN gene for further characterization because the xopNKXO85 mutant showed the greatest influence on virulence. We confirmed that XopNKXO85 is translocated into rice cells, and its gene expression is positively regulated by HrpX. Two rice proteins, OsVOZ2 and a putative thiamine synthase (OsXNP), were identified as targets of XopNKXO85 by yeast two-hybrid screening. Interactions between XopNKXO85 and OsVOZ2 and OsXNP were further confirmed in planta by bimolecular fluorescence complementation and in vivo pull-down assays. To investigate the roles of OsVOZ2 in interactions between rice and Xoo, we evaluated the virulence of the wild-type KXO85 and xopNKXO85 mutant in the OsVOZ2 mutant line PFG_3A-07565 of Dongjin. The wild-type KXO85 and xopNKXO85 mutant were significantly less virulent in the mutant rice line. These results indicate that XopNKXO85 and OsVOZ2 play important roles both individually and together for Xoo virulence in rice. PMID:24019919

Cheong, Hoon; Kim, Chi-Yeol; Jeon, Jong-Seong; Lee, Byoung-Moo; Sun Moon, Jae; Hwang, Ingyu

2013-01-01

6

Identification of a Novel Effector Domain of BIN1 for Cancer Suppression  

E-print Network

that the coiled-coil BIN1 BAR peptide encodes a novel BIN1 MID domain, through which BIN1 acts as a MYCIdentification of a Novel Effector Domain of BIN1 for Cancer Suppression Greta L. Lundgaard,1 Natae interacts with and inhibits the c-MYC transcription factor through the BIN1 MYC-binding domain (MBD

Kihara, Daisuke

7

Suppression of Plant Resistance Gene-Based Immunity by a Fungal Effector  

PubMed Central

The innate immune system of plants consists of two layers. The first layer, called basal resistance, governs recognition of conserved microbial molecules and fends off most attempted invasions. The second layer is based on Resistance (R) genes that mediate recognition of effectors, proteins secreted by pathogens to suppress or evade basal resistance. Here, we show that a plant-pathogenic fungus secretes an effector that can both trigger and suppress R gene-based immunity. This effector, Avr1, is secreted by the xylem-invading fungus Fusarium oxysporum f.sp. lycopersici (Fol) and triggers disease resistance when the host plant, tomato, carries a matching R gene (I or I-1). At the same time, Avr1 suppresses the protective effect of two other R genes, I-2 and I-3. Based on these observations, we tentatively reconstruct the evolutionary arms race that has taken place between tomato R genes and effectors of Fol. This molecular analysis has revealed a hitherto unpredicted strategy for durable disease control based on resistance gene combinations. PMID:18464895

Houterman, Petra M.; Cornelissen, Ben J. C.; Rep, Martijn

2008-01-01

8

Pseudomonas syringae Effector HopF2 Suppresses Arabidopsis Immunity by Targeting BAK1  

PubMed Central

Summary Pseudomonas syringae delivers a plethora of effector proteins into host cells to sabotage immune responses and modulate physiology to favor infection. We have previously shown that P. syringae pv. tomato DC3000 effector HopF2 suppresses Arabidopsis innate immunity triggered by multiple microbe-associated molecular patterns (MAMP) at the plasma membrane. We show here that HopF2 possesses distinct mechanisms in the suppression of two branches of MAMP-activated MAP kinase (MPK) cascades. Besides blocking MKK5 (MPK kinase 5) activation in the MEKK1/MEKKs-MKK4/5-MPK3/6 cascade, HopF2 targets additional component(s) upstream of MEKK1 in the MEKK1-MKK1/2-MPK4 cascade and plasma membrane-localized receptor-like cytoplasmic kinase BIK1 and its homologs. We further show that HopF2 directly targets BAK1, a plasma membrane-localized receptor-like kinase involved in multiple MAMP signaling. The interaction between BAK1 and HopF2 or two other P. syringae effectors AvrPto and AvrPtoB, was confirmed in vivo and in vitro. Consistent with BAK1 as a physiological target of AvrPto, AvrPtoB and HopF2, the strong growth defects or lethality associated with ectopic expression of these effectors in wild-type Arabidopsis transgenic plants were largely alleviated in bak1 mutant plants. Thus, our results provide genetic evidence to further support that BAK1 is a physiological target of AvrPto, AvrPtoB and HopF2. Identification of BAK1 as an additional target of HopF2 virulence not only explains HopF2 suppression of multiple MAMP signaling at the plasma membrane, but also supports the notion that pathogen virulence effectors act through multiple targets in host cells. PMID:24237140

Zhou, Jinggeng; Wu, Shujing; Chen, Xin; Liu, Chenglong; Sheen, Jen; Shan, Libo; He, Ping

2014-01-01

9

A J-domain Virulence Effector of Pseudomonas syringae Remodels Host Chloroplasts and Suppresses Defenses  

PubMed Central

Summary Background The plant pathogen Pseudomonas syringae injects 20–40 different proteins called effectors into host plant cells, yet the functions and sites of action of these effectors in promoting pathogenesis is largely unknown. Plants in turn defend themselves against P. syringae by activating the salicylic acid (SA)-mediated signaling pathway. The P. syringae-specific HopI1 effector has a putative chloroplast targeting sequence and a J domain. J domains function by activating 70-kDa heat shock proteins (Hsp70). Results HopI1 is an ubiquitous P. syringae virulence effector that acts inside plant cells. When expressed in plants, HopI1 localizes to chloroplasts, the site of SA synthesis. HopI1 causes chloroplast thylakoid structure remodeling and suppresses SA accumulation. HopI1’s C terminus has bona fide J-domain activity that is necessary for HopI1-mediated virulence and thylakoid remodeling. Furthermore, HopI1-expressing plants have increased heat tolerance, establishing that HopI1 can engage the plant stress response machinery. Conclusions These results strongly suggest that chloroplast Hsp70 is targeted by the P. syringae HopI1 effector to promote bacterial virulence by suppressing plant defenses. The targeting of Hsp70 function through J-domain proteins is known to occur in a mammalian virus, SV40. However, this is the first example of a bacterial pathogen exploiting a J-domain protein to promote pathogenesis through alterations of chloroplast structure and function. PMID:17350264

Jelenska, Joanna; Yao, Nan; Vinatzer, Boris A.; Wright, Christine M.; Brodsky, Jeffrey L.; Greenberg, Jean T.

2007-01-01

10

Bach2 maintains T cells in a naive state by suppressing effector memory-related genes.  

PubMed

The transcriptional repressor BTB and CNC homology 2 (Bach2) is thought to be mainly expressed in B cells with specific functions such as class switch recombination and somatic hypermutation, but its function in T cells is not known. We found equal Bach2 expression in T cells and analyzed its function using Bach2-deficient (-/-) mice. Although T-cell development was normal, numbers of peripheral naive T cells were decreased, which rapidly produced Th2 cytokines after TCR stimulation. Bach2(-/-) naive T cells highly expressed genes related to effector-memory T cells such as CCR4, ST-2 and Blimp-1. Enhanced expression of these genes induced Bach2(-/-) naive T cells to migrate toward CCR4-ligand and respond to IL33. Forced expression of Bach2 restored the expression of these genes. Using Chromatin Immunoprecipitation (ChIP)-seq analysis, we identified S100 calcium binding protein a, Heme oxigenase 1, and prolyl hydroxylase 3 as Bach2 direct target genes, which are highly expressed in effector-memory T cells. These findings indicate that Bach2 suppresses effector memory-related genes to maintain the naive T-cell state and regulates generation of effector-memory T cells. PMID:23754397

Tsukumo, Shin-ichi; Unno, Midori; Muto, Akihiko; Takeuchi, Arata; Kometani, Kohei; Kurosaki, Tomohiro; Igarashi, Kazuhiko; Saito, Takashi

2013-06-25

11

Two host cytoplasmic effectors are required for pathogenesis of Phytophthora sojae by suppression of host defenses.  

PubMed

Phytophthora sojae encodes hundreds of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling- and necrosis-inducing proteins (CRN) or Crinkler. Their functions and mechanisms in pathogenesis are mostly unknown. Here, we identify a group of five P. sojae-specific CRN-like genes with high levels of sequence similarity, of which three are putative pseudogenes. Functional analysis shows that the two functional genes encode proteins with predicted nuclear localization signals that induce contrasting responses when expressed in Nicotiana benthamiana and soybean (Glycine max). PsCRN63 induces cell death, while PsCRN115 suppresses cell death elicited by the P. sojae necrosis-inducing protein (PsojNIP) or PsCRN63. Expression of CRN fragments with deleted signal peptides and FLAK motifs demonstrates that the carboxyl-terminal portions of PsCRN63 or PsCRN115 are sufficient for their activities. However, the predicted nuclear localization signal is required for PsCRN63 to induce cell death but not for PsCRN115 to suppress cell death. Furthermore, silencing of the PsCRN63 and PsCRN115 genes in P. sojae stable transformants leads to a reduction of virulence on soybean. Intriguingly, the silenced transformants lose the ability to suppress host cell death and callose deposition on inoculated plants. These results suggest a role for CRN effectors in the suppression of host defense responses. PMID:21071601

Liu, Tingli; Ye, Wenwu; Ru, Yanyan; Yang, Xinyu; Gu, Biao; Tao, Kai; Lu, Shan; Dong, Suomeng; Zheng, Xiaobo; Shan, Weixing; Wang, Yuanchao; Dou, Daolong

2011-01-01

12

Phytophthora sojae Effector PsCRN70 Suppresses Plant Defenses in Nicotiana benthamiana  

PubMed Central

Phytophthora sojae, an oomycete pathogen, produces a large number of effector proteins that enter into host cells. The Crinklers (Crinkling and Necrosis, CRN) are cytoplasmic effectors that are conserved in oomycete pathogens and their encoding genes are highly expressed at the infective stages in P. sojae. However, their roles in pathogenesis are largely unknown. Here, we functionally characterized an effector PsCRN70 by transiently and stably overexpressing it in Nicotiana benthamiana. We demonstrated that PsCRN70 was localized to the plant cell nucleus and suppressed cell death elicited by all the tested cell death-inducing proteins, including BAX, PsAvh241, PsCRN63, PsojNIP and R3a/Avr3a. Overexpression of the PsCRN70 gene in N. benthamiana enhanced susceptibility to P. parasitica. The H2O2 accumulation in the PsCRN70-transgenic plants was reduced compared to the GFP-lines. The transcriptional levels of the defense-associated genes, including PR1b, PR2b, ERF1 and LOX, were also down-regulated in the PsCRN70-transgenic lines. Our results suggest that PsCRN70 may function as a universal suppressor of the cell death induced by many elicitors, the host H2O2 accumulation and the expression of defense-associated genes, and therefore promotes pathogen infection. PMID:24858571

Ru, Yanyan; Liu, Tingli; Xu, Jing; Liu, Li; Mafurah, Joseph Juma; Dou, Daolong

2014-01-01

13

Multiple Candidate Effectors from the Oomycete Pathogen Hyaloperonospora arabidopsidis Suppress Host Plant Immunity  

PubMed Central

Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis). We investigated if candidate effectors predicted in the genome sequence of Hpa isolate Emoy2 (HaRxLs) were able to manipulate host defenses in different Arabidopsis accessions. We developed a rapid and sensitive screening method to test HaRxLs by delivering them via the bacterial type-three secretion system (TTSS) of Pseudomonas syringae pv tomato DC3000-LUX (Pst-LUX) and assessing changes in Pst-LUX growth in planta on 12 Arabidopsis accessions. The majority (?70%) of the 64 candidates tested positively contributed to Pst-LUX growth on more than one accession indicating that Hpa virulence likely involves multiple effectors with weak accession-specific effects. Further screening with a Pst mutant (?CEL) showed that HaRxLs that allow enhanced Pst-LUX growth usually suppress callose deposition, a hallmark of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). We found that HaRxLs are rarely strong avirulence determinants. Although some decreased Pst-LUX growth in particular accessions, none activated macroscopic cell death. Fewer HaRxLs conferred enhanced Pst growth on turnip, a non-host for Hpa, while several reduced it, consistent with the idea that turnip's non-host resistance against Hpa could involve a combination of recognized HaRxLs and ineffective HaRxLs. We verified our results by constitutively expressing in Arabidopsis a sub-set of HaRxLs. Several transgenic lines showed increased susceptibility to Hpa and attenuation of Arabidopsis PTI responses, confirming the HaRxLs' role in Hpa virulence. This study shows TTSS screening system provides a useful tool to test whether candidate effectors from eukaryotic pathogens can suppress/trigger plant defense mechanisms and to rank their effectiveness prior to subsequent mechanistic investigation. PMID:22072967

Fabro, Georgina; Steinbrenner, Jens; Coates, Mary; Ishaque, Naveed; Baxter, Laura; Studholme, David J.; Körner, Evelyn; Allen, Rebecca L.; Piquerez, Sophie J. M.; Rougon-Cardoso, Alejandra; Greenshields, David; Lei, Rita; Badel, Jorge L.; Caillaud, Marie-Cecile; Sohn, Kee-Hoon; Van den Ackerveken, Guido; Parker, Jane E.; Beynon, Jim; Jones, Jonathan D. G.

2011-01-01

14

Neutrophil effector responses are suppressed by secretory phospholipase A2 modified HDL.  

PubMed

Secretory phospholipase A2 (sPLA2) generates bioactive lysophospholipids implicated in acute and chronic inflammation, but the pathophysiologic role of sPLA2 is poorly understood. Given that high-density lipoprotein (HDL) is the major substrate for sPLA2 in plasma, we investigated the effects of sPLA2-mediated modification of HDL (sPLA2-HDL) on neutrophil function, an essential arm of the innate immune response and atherosclerosis. Treatment of neutrophils with sPLA2-HDL rapidly prevented agonist-induced neutrophil activation, including shape change, neutrophil extracellular trap formation, CD11b activation, adhesion under flow and migration of neutrophils. The cholesterol-mobilizing activity of sPLA2-HDL was markedly increased when compared to native HDL, promoting a significant reduction of cholesterol-rich signaling microdomains integral to cellular signaling pathways. Moreover, sPLA2-HDL effectively suppressed agonist-induced rise in intracellular Ca(2+) levels. Native HDL showed no significant effects and removing lysophospholipids from sPLA2-HDL abolished all anti-inflammatory activities. Overall, our studies suggest that the increased cholesterol-mobilizing activity of sPLA2-HDL and suppression of rise in intracellular Ca(2+) levels are likely mechanism that counteracts agonist-induced activation of neutrophils. These counterintuitive findings imply that neutrophil trafficking and effector responses are altered by sPLA2-HDL during inflammatory conditions. PMID:25463476

Curcic, Sanja; Holzer, Michael; Frei, Robert; Pasterk, Lisa; Schicho, Rudolf; Heinemann, Akos; Marsche, Gunther

2015-02-01

15

The Pseudomonas syringae type III effector HopG1 targets mitochondria, alters plant development, and suppresses plant innate immunity  

PubMed Central

Summary The bacterial plant pathogen Pseudomonas syringae uses a type III protein secretion system to inject type III effectors into plant cells. Primary targets of these effectors appear to be effector-triggered immunity (ETI) and pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). The type III effector HopG1 is a suppressor of ETI that is broadly conserved in bacterial plant pathogens. Here we show that HopG1 from P. syringae pv. tomato DC3000 also suppresses PTI. Interestingly, HopG1 localizes to plant mitochondria, suggesting that its suppression of innate immunity may be linked to a perturbation of mitochondrial function. While HopG1 possesses no obvious mitochondrial signal peptide, its N-terminal two-thirds was sufficient for mitochondrial localization. A HopG1-GFP fusion lacking HopG1’s N-terminal 13 amino acids was not localized to the mitochondria reflecting the importance of the N-terminus for targeting. Constitutive expression of HopG1 in Arabidopsis thaliana, Nicotiana tabacum (tobacco) and Lycopersicon esculentum (tomato) dramatically alters plant development resulting in dwarfism, increased branching and infertility. Constitutive expression of HopG1 in planta leads to reduced respiration rates and an increased basal level of reactive oxygen species. These findings suggest that HopG1’s target is mitochondrial and that effector/target interaction promotes disease by disrupting mitochondrial functions. PMID:19863557

Block, Anna; Guo, Ming; Li, Guangyong; Elowsky, Christian; Clemente, Thomas E.; Alfano, James R.

2009-01-01

16

Multiple Candidate Effectors from the Oomycete Pathogen Hyaloperonospora arabidopsidis Suppress Host Plant Immunity  

Microsoft Academic Search

Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis). We investigated if candidate effectors predicted in the genome sequence

Georgina Fabro; Jens Steinbrenner; Mary Coates; Naveed Ishaque; Laura Baxter; David J. Studholme; Evelyn Körner; Rebecca L. Allen; Sophie J. M. Piquerez; Alejandra Rougon-Cardoso; David Greenshields; Rita Lei; Jorge L. Badel; Marie-Cecile Caillaud; Kee-Hoon Sohn; Guido Van den Ackerveken; Jane E. Parker; Jim Beynon; Jonathan D. G. Jones

2011-01-01

17

Homologous RXLR effectors from Hyaloperonospora arabidopsidis and Phytophthora sojae suppress immunity in distantly related plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diverse pathogens secrete effector proteins into plant cells to manipulate host cellular processes. Oomycete pathogens contain very large complements of predicted effector genes defined by an RXLR host cell entry motif. The genome of Hyaloperonospora arabidopsidis (Hpa, downy mildew of Arabidopsis) ...

18

Functional analysis of plant defense suppression and activation by the Xanthomonas core type III effector XopX.  

PubMed

Many phytopathogenic type III secretion effectors (T3Es) have been shown to target and suppress plant immune signaling, but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a "core" Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria (Xe) infection of tomato, but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during Xe infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of Xe-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX co-expression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during Xe-tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses. PMID:25338145

Stork, William; Kim, Jung-Gun; Mudgett, Mary Beth

2014-10-22

19

Functional analysis of plant defense suppression and activation by the Xanthomonas core type III effector XopX  

PubMed Central

Many phytopathogenic type III secretion effectors (T3Es) have been shown to target and suppress plant immune signaling, but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a “core” Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria (Xe) infection of tomato, but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during Xe infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of Xe-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX co-expression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during Xe-tomato interactions, suggesting that XopX’s primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses. PMID:25338145

Stork, William; Kim, Jung-Gun; Mudgett, Mary Beth

2014-01-01

20

Pseudomonas syringae effector AvrPtoB suppresses basal defence in Arabidopsis  

Microsoft Academic Search

Summary The virulence and avirulence activities of members of the Pseudomonas syringae HopAB family of effectors and AvrPto were examined in bean, tomato and Arabidopsis. Proteins were delivered by the RW60 strain of P. syringae pv. phaseolicola. RW60 causes a hypersensitive reaction (HR) in bean and tomato but is restricted without the HR in Arabidopsis. Dual avirulence and virulence functions

Marta de Torres; John W. Mansfield; Nina Grabov; Ian R. Brown; Hassan Ammouneh; George Tsiamis; Alec Forsyth; Silke Robatzek; Murray Grant; Jens Boch

2006-01-01

21

Targeting Effector Memory T Cells with the Small Molecule Kv1.3 Blocker PAP-1 Suppresses Allergic Contact Dermatitis  

PubMed Central

The voltage-gated potassium channel Kv1.3 has been recently identified as a molecular target that allows for selective pharmacological suppression of effector memory T (TEM) cells without affecting the function of naïve and central memory T cells. We here investigated whether PAP-1, a small molecule Kv1.3 blocker (EC50 = 2nM), could suppress allergic contact dermatitis (ACD). In a rat model of ACD, we first confirmed that the infiltrating cells in the elicitation phase are indeed CD8+ CD45RC? memory T cells with high Kv1.3 expression. In accordance with its selective effect on TEM cells, PAP-1 did not impair sensitization, but potently suppressed oxazolone-induced inflammation by inhibiting the infiltration of CD8+ T cells and reducing the production of the inflammatory cytokines IFN- ?, IL-2, and IL-17 when administered intraperitoneally or orally during the elicitation phase. PAP-1 was equally effective when applied topically, demonstrating that it effectively penetrates skin. We further show that PAP-1 is not a sensitizer or an irritant and exhibits no toxicity in a 28-day toxicity study. Based on these results we propose that PAP-1 could potentially be developed into a drug for the topical treatment of inflammatory skin diseases such as psoriasis. PMID:17273162

Azam, Philippe; Sankaranarayanan, Ananthakrishnan; Homerick, Daniel; Griffey, Stephen; Wulff, Heike

2007-01-01

22

Conserved C-Terminal Motifs Required for Avirulence and Suppression of Cell Death by Phytophthora sojae effector Avr1b[W  

PubMed Central

The sequenced genomes of oomycete plant pathogens contain large superfamilies of effector proteins containing the protein translocation motif RXLR-dEER. However, the contributions of these effectors to pathogenicity remain poorly understood. Here, we show that the Phytophthora sojae effector protein Avr1b can contribute positively to virulence and can suppress programmed cell death (PCD) triggered by the mouse BAX protein in yeast, soybean (Glycine max), and Nicotiana benthamiana cells. We identify three conserved motifs (K, W, and Y) in the C terminus of the Avr1b protein and show that mutations in the conserved residues of the W and Y motifs reduce or abolish the ability of Avr1b to suppress PCD and also abolish the avirulence interaction of Avr1b with the Rps1b resistance gene in soybean. W and Y motifs are present in at least half of the identified oomycete RXLR-dEER effector candidates, and we show that three of these candidates also suppress PCD in soybean. Together, these results indicate that the W and Y motifs are critical for the interaction of Avr1b with host plant target proteins and support the hypothesis that these motifs are critical for the functions of the very large number of predicted oomycete effectors that contain them. PMID:18390593

Dou, Daolong; Kale, Shiv D.; Wang, Xinle; Chen, Yubo; Wang, Qunqing; Wang, Xia; Jiang, Rays H.Y.; Arredondo, Felipe D.; Anderson, Ryan G.; Thakur, Poulami B.; McDowell, John M.; Wang, Yuanchao; Tyler, Brett M.

2008-01-01

23

The Pseudomonas syringae Type III Effector HopF2 Suppresses Arabidopsis Stomatal Immunity  

PubMed Central

Pseudomonas syringae subverts plant immune signalling through injection of type III secreted effectors (T3SE) into host cells. The T3SE HopF2 can disable Arabidopsis immunity through Its ADP-ribosyltransferase activity. Proteomic analysis of HopF2 interacting proteins identified a protein complex containing ATPases required for regulating stomatal aperture, suggesting HopF2 may manipulate stomatal immunity. Here we report HopF2 can inhibit stomatal immunity independent of its ADP-ribosyltransferase activity. Transgenic expression of HopF2 in Arabidopsis inhibits stomatal closing in response to P. syringae and increases the virulence of surface inoculated P. syringae. Further, transgenic expression of HopF2 inhibits flg22 induced reactive oxygen species production. Intriguingly, ADP-ribosyltransferase activity is dispensable for inhibiting stomatal immunity and flg22 induced reactive oxygen species. Together, this implies HopF2 may be a bifunctional T3SE with ADP-ribosyltransferase activity required for inhibiting apoplastic immunity and an independent function required to inhibit stomatal immunity. PMID:25503437

Hurley, Brenden; Lee, Donghyuk; Mott, Adam; Wilton, Michael; Liu, Jun; Liu, Yulu C.; Angers, Stephane; Coaker, Gitta

2014-01-01

24

Calcitriol Suppresses Antiretinal Autoimmunity through Inhibitory Effects on the Th17 Effector Response1  

PubMed Central

Experimental autoimmune uveitis (EAU) serves as a model for human autoimmune uveitis and for cell-mediated autoimmunity in general. EAU induced in mice by immunization with the retinal Ag interphotoreceptor retinoid-binding protein in CFA is driven by the Th17 response. Oral calcitriol (1,25-dihydroxyvitamin D3) prevented as well as partly reversed disease and suppressed immunological responses. In vitro, calcitriol directly suppressed IL-17 induction in purified naive CD4+ T cells without inhibiting Th17 lineage commitment, as reflected by unaltered ROR?t, STAT3, and FoxP3 expression. In contrast, in vivo treatment with calcitriol of mice challenged for EAU impaired commitment to the Th17 lineage, as judged by reduction of both ROR?t and IL-17 in CD4+ T cells. Innate immune response parameters in draining lymph nodes of treated mice were suppressed, as was production of IL-1, IL-6, TNF-?, and IL-12/IL-23p40, but not IL-10, by explanted splenic dendritic cells (DC). Finally, supernatants of calcitriol-conditioned bone marrow-derived DC had reduced ability to support Th17 polarization of naive CD4+ T cells in vitro and in vivo. Thus, calcitriol appears to suppress autoimmunity by inhibiting the Th17 response at several levels, including the ability of DC to support priming of Th17 cells, the ability of CD4+ T cells to commit to the Th17 lineage, and the ability of committed Th17 T cells to produce IL-17. PMID:19342637

Tang, Jun; Zhou, Ru; Luger, Dror; Zhu, Wei; Silver, Phyllis B.; Grajewski, Rafael S.; Su, Shao-Bo; Chan, Chi-Chao; Adorini, Luciano; Caspi, Rachel R.

2009-01-01

25

Analysis of Putative Apoplastic Effectors from the Nematode, Globodera rostochiensis, and Identification of an Expansin-Like Protein That Can Induce and Suppress Host Defenses  

PubMed Central

The potato cyst nematode, Globodera rostochiensis, is an important pest of potato. Like other pathogens, plant parasitic nematodes are presumed to employ effector proteins, secreted into the apoplast as well as the host cytoplasm, to alter plant cellular functions and successfully infect their hosts. We have generated a library of ORFs encoding putative G. rostochiensis putative apoplastic effectors in vectors for expression in planta. These clones were assessed for morphological and developmental effects on plants as well as their ability to induce or suppress plant defenses. Several CLAVATA3/ESR-like proteins induced developmental phenotypes, whereas predicted cell wall-modifying proteins induced necrosis and chlorosis, consistent with roles in cell fate alteration and tissue invasion, respectively. When directed to the apoplast with a signal peptide, two effectors, an ubiquitin extension protein (GrUBCEP12) and an expansin-like protein (GrEXPB2), suppressed defense responses including NB-LRR signaling induced in the cytoplasm. GrEXPB2 also elicited defense response in species- and sequence-specific manner. Our results are consistent with the scenario whereby potato cyst nematodes secrete effectors that modulate host cell fate and metabolism as well as modifying host cell walls. Furthermore, we show a novel role for an apoplastic expansin-like protein in suppressing intra-cellular defense responses. PMID:25606855

Ali, Shawkat; Magne, Maxime; Chen, Shiyan; Côté, Olivier; Stare, Barbara Geri?; Obradovic, Natasa; Jamshaid, Lubna; Wang, Xiaohong; Bélair, Guy; Moffett, Peter

2015-01-01

26

Effector-mediated suppression of chitin-triggered immunity by magnaporthe oryzae is necessary for rice blast disease.  

PubMed

Plants use pattern recognition receptors to defend themselves from microbial pathogens. These receptors recognize pathogen-associated molecular patterns (PAMPs) and activate signaling pathways that lead to immunity. In rice (Oryza sativa), the chitin elicitor binding protein (CEBiP) recognizes chitin oligosaccharides released from the cell walls of fungal pathogens. Here, we show that the rice blast fungus Magnaporthe oryzae overcomes this first line of plant defense by secreting an effector protein, Secreted LysM Protein1 (Slp1), during invasion of new rice cells. We demonstrate that Slp1 accumulates at the interface between the fungal cell wall and the rice plasma membrane, can bind to chitin, and is able to suppress chitin-induced plant immune responses, including generation of reactive oxygen species and plant defense gene expression. Furthermore, we show that Slp1 competes with CEBiP for binding of chitin oligosaccharides. Slp1 is required by M. oryzae for full virulence and exerts a significant effect on tissue invasion and disease lesion expansion. By contrast, gene silencing of CEBiP in rice allows M. oryzae to cause rice blast disease in the absence of Slp1. We propose that Slp1 sequesters chitin oligosaccharides to prevent PAMP-triggered immunity in rice, thereby facilitating rapid spread of the fungus within host tissue. PMID:22267486

Mentlak, Thomas A; Kombrink, Anja; Shinya, Tomonori; Ryder, Lauren S; Otomo, Ippei; Saitoh, Hiromasa; Terauchi, Ryohei; Nishizawa, Yoko; Shibuya, Naoto; Thomma, Bart P H J; Talbot, Nicholas J

2012-01-01

27

Phytophthora infestans RXLR Effector PexRD2 Interacts with Host MAPKKK? to Suppress Plant Immune Signaling[W][OPEN  

PubMed Central

Mitogen-activated protein kinase cascades are key players in plant immune signaling pathways, transducing the perception of invading pathogens into effective defense responses. Plant pathogenic oomycetes, such as the Irish potato famine pathogen Phytophthora infestans, deliver RXLR effector proteins to plant cells to modulate host immune signaling and promote colonization. Our understanding of the molecular mechanisms by which these effectors act in plant cells is limited. Here, we report that the P. infestans RXLR effector PexRD2 interacts with the kinase domain of MAPKKK?, a positive regulator of cell death associated with plant immunity. Expression of PexRD2 or silencing MAPKKK? in Nicotiana benthamiana enhances susceptibility to P. infestans. We show that PexRD2 perturbs signaling pathways triggered by or dependent on MAPKKK?. By contrast, homologs of PexRD2 from P. infestans had reduced or no interaction with MAPKKK? and did not promote disease susceptibility. Structure-led mutagenesis identified PexRD2 variants that do not interact with MAPKKK? and fail to support enhanced pathogen growth or perturb MAPKKK? signaling pathways. Our findings provide evidence that P. infestans RXLR effector PexRD2 has evolved to interact with a specific host MAPKKK to perturb plant immunity–related signaling. PMID:24632534

King, Stuart R.F.; McLellan, Hazel; Boevink, Petra C.; Armstrong, Miles R.; Bukharova, Tatyana; Sukarta, Octavina; Win, Joe; Kamoun, Sophien; Birch, Paul R.J.; Banfield, Mark J.

2014-01-01

28

CD4+ CD25+ regulatory T cells suppress contact hypersensitivity reactions by blocking influx of effector T cells into inflamed tissue.  

PubMed

CD4+ CD25+ regulatory T cells (Treg) exert suppressive functions on effector T cells in vitro and in vivo. However, the exact cellular events that mediate this inhibitory action remain largely unclear. To elucidate these events, we used intravital microscopy in a model of contact hypersensitivity (CHS) and visualized the leukocyte-endothelium interaction at the site of antigen challenge in awake C57BL/6 mice. Injection of Treg i.v. into sensitized mice at the time of local hapten challenge significantly inhibited rolling and adhesion of endogenous leukocytes to the endothelium. A similar inhibition of leukocyte recruitment could be recorded after injection of Treg-derived tissue culture supernatant. Thus, these data indicate that soluble factors may account for the suppressive effects. Accordingly we found that IL-10, but not TGF-beta, was produced by Treg upon stimulation and that addition of anti-IL-10 antibodies abrogated the suppressive effects of Treg and tissue culture supernatant in CHS reactions. Moreover, CD4+ CD25+ T cells isolated from IL-10-/- mice were not able to suppress the immune response induced by hapten treatment in C57BL/6 mice. In conclusion, our data suggest that cytokine-dependent rather than cell-cell contact-dependent mechanisms play a pivotal role in the suppression of CHS reactions by Treg in vivo. PMID:17048272

Ring, Sabine; Schäfer, Stephan C; Mahnke, Karsten; Lehr, Hans-Anton; Enk, Alexander H

2006-11-01

29

The Magnaporthe oryzae Effector AvrPiz-t Targets the RING E3 Ubiquitin Ligase APIP6 to Suppress Pathogen-Associated Molecular Pattern–Triggered Immunity in Rice[W][OA  

PubMed Central

Although the functions of a few effector proteins produced by bacterial and oomycete plant pathogens have been elucidated in recent years, information for the vast majority of pathogen effectors is still lacking, particularly for those of plant-pathogenic fungi. Here, we show that the avirulence effector AvrPiz-t from the rice blast fungus Magnaporthe oryzae preferentially accumulates in the specialized structure called the biotrophic interfacial complex and is then translocated into rice (Oryza sativa) cells. Ectopic expression of AvrPiz-t in transgenic rice suppresses the flg22- and chitin-induced generation of reactive oxygen species (ROS) and enhances susceptibility to M. oryzae, indicating that AvrPiz-t functions to suppress pathogen-associated molecular pattern (PAMP)-triggered immunity in rice. Interaction assays show that AvrPiz-t suppresses the ubiquitin ligase activity of the rice RING E3 ubiquitin ligase APIP6 and that, in return, APIP6 ubiquitinates AvrPiz-t in vitro. Interestingly, agroinfection assays reveal that AvrPiz-t and AvrPiz-t Interacting Protein 6 (APIP6) are both degraded when coexpressed in Nicotiana benthamiana. Silencing of APIP6 in transgenic rice leads to a significant reduction of flg22-induced ROS generation, suppression of defense-related gene expression, and enhanced susceptibility of rice plants to M. oryzae. Taken together, our results reveal a mechanism in which a fungal effector targets the host ubiquitin proteasome system for the suppression of PAMP-triggered immunity in plants. PMID:23204406

Park, Chan-Ho; Chen, Songbiao; Shirsekar, Gautam; Zhou, Bo; Khang, Chang Hyun; Songkumarn, Pattavipha; Afzal, Ahmed J.; Ning, Yuese; Wang, Ruyi; Bellizzi, Maria; Valent, Barbara; Wang, Guo-Liang

2012-01-01

30

The Magnaporthe oryzae effector AvrPiz-t targets the RING E3 ubiquitin ligase APIP6 to suppress pathogen-associated molecular pattern-triggered immunity in rice.  

PubMed

Although the functions of a few effector proteins produced by bacterial and oomycete plant pathogens have been elucidated in recent years, information for the vast majority of pathogen effectors is still lacking, particularly for those of plant-pathogenic fungi. Here, we show that the avirulence effector AvrPiz-t from the rice blast fungus Magnaporthe oryzae preferentially accumulates in the specialized structure called the biotrophic interfacial complex and is then translocated into rice (Oryza sativa) cells. Ectopic expression of AvrPiz-t in transgenic rice suppresses the flg22- and chitin-induced generation of reactive oxygen species (ROS) and enhances susceptibility to M. oryzae, indicating that AvrPiz-t functions to suppress pathogen-associated molecular pattern (PAMP)-triggered immunity in rice. Interaction assays show that AvrPiz-t suppresses the ubiquitin ligase activity of the rice RING E3 ubiquitin ligase APIP6 and that, in return, APIP6 ubiquitinates AvrPiz-t in vitro. Interestingly, agroinfection assays reveal that AvrPiz-t and AvrPiz-t Interacting Protein 6 (APIP6) are both degraded when coexpressed in Nicotiana benthamiana. Silencing of APIP6 in transgenic rice leads to a significant reduction of flg22-induced ROS generation, suppression of defense-related gene expression, and enhanced susceptibility of rice plants to M. oryzae. Taken together, our results reveal a mechanism in which a fungal effector targets the host ubiquitin proteasome system for the suppression of PAMP-triggered immunity in plants. PMID:23204406

Park, Chan-Ho; Chen, Songbiao; Shirsekar, Gautam; Zhou, Bo; Khang, Chang Hyun; Songkumarn, Pattavipha; Afzal, Ahmed J; Ning, Yuese; Wang, Ruyi; Bellizzi, Maria; Valent, Barbara; Wang, Guo-Liang

2012-11-01

31

The interaction of the novel 30C02 cyst nematode effector protein with a plant ?-1,3-endoglucanase may suppress host defence to promote parasitism.  

PubMed

Phytoparasitic nematodes secrete an array of effector proteins to modify selected recipient plant cells into elaborate and essential feeding sites. The biological function of the novel 30C02 effector protein of the soybean cyst nematode, Heterodera glycines, was studied using Arabidopsis thaliana as host and the beet cyst nematode, Heterodera schachtii, which contains a homologue of the 30C02 gene. Expression of Hg30C02 in Arabidopsis did not affect plant growth and development but increased plant susceptibility to infection by H. schachtii. The 30C02 protein interacted with a specific (AT4G16260) host plant ?-1,3-endoglucanase in both yeast and plant cells, possibly to interfere with its role as a plant pathogenesis-related protein. Interestingly, the peak expression of 30C02 in the nematode and peak expression of At4g16260 in plant roots coincided at around 3-5 d after root infection by the nematode, after which the relative expression of At4g16260 declined significantly. An Arabidopsis At4g16260 T-DNA mutant showed increased susceptibility to cyst nematode infection, and plants that overexpressed At4g16260 were reduced in nematode susceptibility, suggesting a potential role of host ?-1,3-endoglucanase in the defence response against H. schachtii infection. Arabidopsis plants that expressed dsRNA and its processed small interfering RNA complementary to the Hg30C02 sequence were not phenotypically different from non-transformed plants, but they exhibited a strong RNA interference-mediated resistance to infection by H. schachtii. The collective results suggest that, as with other pathogens, active suppression of host defence is a critical component for successful parasitism by nematodes and a vulnerable target to disrupt the parasitic cycle. PMID:22442414

Hamamouch, Noureddine; Li, Chunying; Hewezi, Tarek; Baum, Thomas J; Mitchum, Melissa G; Hussey, Richard S; Vodkin, Lila O; Davis, Eric L

2012-06-01

32

T cell directed immunotherapy of inflammatory demyelination in the peripheral nervous system. Potent suppression of the effector phase of experimental autoimmune neuritis by anti-CD2 antibodies.  

PubMed

Experimental autoimmune neuritis (EAN) of Lewis rats, an inflammatory demyelinating neuropathy and model of the human Guillain-Barré syndrome (GBS), was used to evaluate the novel T cell directed immunotherapy with the anti-CD2 monoclonal antibody (mAb) OX34. Clinical signs of EAN actively induced by immunization with bovine peripheral nerve myelin in complete Freund's adjuvant (CFA) were totally prevented or markedly suppressed by preventative injections of OX34 starting 8 days post-immunization (p.i.). Moreover, therapeutic application of the mAb beginning on the day of first clinical signs of EAN markedly inhibited progression of disease. Electrophysiological and histological investigation of sciatic nerves 17 and 18 days p.i. respectively, also revealed an inhibitory effect of OX34 on EAN-associated functional and morphological nerve damage. Similarly, therapeutic injections of OX34 after onset of EAN actively induced by immunization with a neuritogenic peptide of the P2 protein completely halted further deterioration of clinical disease. Finally, clinical, electrophysiological and histological signs of adoptive transfer EAN mediated by injection of neuritogenic T helper line cells were prevented or strongly suppressed by OX34-application on the day of cell transfer and 4 days later, underlying the impact of the mAb on the effector phase of the disease. Since the anti-CD2 mAb did not exert its effect by inhibition of T cell activation, induction of anergy, modulation of CD2 antigens, or by T cell depletion, we assume that it may affect migration of T lymphocytes across the blood-nerve barrier. The immediate and marked suppression of ongoing EAN by the mAb lead to the recommendation of anti-CD2 mAbs as candidates for T cell directed immunotherapy of the GBS. PMID:8813272

Jung, S; Toyka, K; Hartung, H P

1996-08-01

33

Xanthomonas Type III Effector XopD Desumoylates Tomato Transcription Factor SlERF4 to Suppress Ethylene Responses and Promote Pathogen Growth  

PubMed Central

SUMMARY XopD, a type III secretion effector from Xanthomonas euvesicatoria (Xcv), the causal agent of bacterial spot of tomato is required for pathogen growth and delay of host symptom development. XopD carries a C-terminal SUMO protease domain, a host range determining non-specific DNA-binding domain and two EAR motifs typically found in repressors of stress-induced transcription. The precise target(s) and mechanism(s) of XopD are obscure. We report that XopD directly targets the tomato ethylene responsive transcription factor SlERF4 to suppress ethylene production, which is required for anti-Xcv immunity and symptom development. SlERF4 expression was required for Xcv ?xopD-induced ethylene production and ethylene -stimulated immunity. XopD colocalized with SlERF4 in subnuclear foci and catalyzed SUMO1 hydrolysis from lysine 53 of SlERF4 causing SlERF4 destabilization. Mutation of lysine 53 prevented SlERF4 sumoylation, decreased SlERF4 levels, and reduced SlERF4 transcription. These data suggest that XopD desumoylates SlERF4 to repress ethylene induced-transcription required for anti-Xcv immunity. PMID:23414755

Kim, Jung-Gun; Stork, William; Mudgett, Mary Beth

2013-01-01

34

Suppression of the SOX2 neural effector gene by PRDM1 promotes human germ cell fate in embryonic stem cells.  

PubMed

The mechanisms of transcriptional regulation underlying human primordial germ cell (PGC) differentiation are largely unknown. The transcriptional repressor Prdm1/Blimp-1 is known to play a critical role in controlling germ cell specification in mice. Here, we show that PRDM1 is expressed in developing human gonads and contributes to the determination of germline versus neural fate in early development. We show that knockdown of PRDM1 in human embryonic stem cells (hESCs) impairs germline potential and upregulates neural genes. Conversely, ectopic expression of PRDM1 in hESCs promotes the generation of cells that exhibit phenotypic and transcriptomic features of early PGCs. Furthermore, PRDM1 suppresses transcription of SOX2. Overexpression of SOX2 in hESCs under conditions favoring germline differentiation skews cell fate from the germline to the neural lineage. Collectively, our results demonstrate that PRDM1 serves as a molecular switch to modulate the divergence of neural or germline fates through repression of SOX2 during human development. PMID:24527393

Lin, I-Ying; Chiu, Feng-Lan; Yeang, Chen-Hsiang; Chen, Hsin-Fu; Chuang, Ching-Yu; Yang, Shii-Yi; Hou, Pei-Shan; Sintupisut, Nardnisa; Ho, Hong-Nerng; Kuo, Hung-Chih; Lin, Kuo-I

2014-02-11

35

Suppression of the SOX2 Neural Effector Gene by PRDM1 Promotes Human Germ Cell Fate in Embryonic Stem Cells  

PubMed Central

Summary The mechanisms of transcriptional regulation underlying human primordial germ cell (PGC) differentiation are largely unknown. The transcriptional repressor Prdm1/Blimp-1 is known to play a critical role in controlling germ cell specification in mice. Here, we show that PRDM1 is expressed in developing human gonads and contributes to the determination of germline versus neural fate in early development. We show that knockdown of PRDM1 in human embryonic stem cells (hESCs) impairs germline potential and upregulates neural genes. Conversely, ectopic expression of PRDM1 in hESCs promotes the generation of cells that exhibit phenotypic and transcriptomic features of early PGCs. Furthermore, PRDM1 suppresses transcription of SOX2. Overexpression of SOX2 in hESCs under conditions favoring germline differentiation skews cell fate from the germline to the neural lineage. Collectively, our results demonstrate that PRDM1 serves as a molecular switch to modulate the divergence of neural or germline fates through repression of SOX2 during human development. PMID:24527393

Lin, I-Ying; Chiu, Feng-Lan; Yeang, Chen-Hsiang; Chen, Hsin-Fu; Chuang, Ching-Yu; Yang, Shii-Yi; Hou, Pei-Shan; Sintupisut, Nardnisa; Ho, Hong-Nerng; Kuo, Hung-Chih; Lin, Kuo-I

2014-01-01

36

A genetic screen to isolate type III effectors translocated into pepper cells during Xanthomonas infection.  

PubMed

The bacterial pathogen Xanthomonas campestris pv. vesicatoria (Xcv) uses a type III secretion system (TTSS) to translocate effector proteins into host plant cells. The TTSS is required for Xcv colonization, yet the identity of many proteins translocated through this apparatus is not known. We used a genetic screen to functionally identify Xcv TTSS effectors. A transposon 5 (Tn5)-based transposon construct including the coding sequence for the Xcv AvrBs2 effector devoid of its TTSS signal was randomly inserted into the Xcv genome. Insertion of the avrBs2 reporter gene into Xcv genes coding for proteins containing a functional TTSS signal peptide resulted in the creation of chimeric TTSS effector::AvrBs2 fusion proteins. Xcv strains containing these fusions translocated the AvrBs2 reporter in a TTSS-dependent manner into resistant BS2 pepper cells during infection, activating the avrBs2-dependent hypersensitive response (HR). We isolated seven chimeric fusion proteins and designated the identified TTSS effectors as Xanthomonas outer proteins (Xops). Translocation of each Xop was confirmed by using the calmodulin-dependent adenylate cydase reporter assay. Three xop genes are Xanthomonas spp.-specific, whereas homologs for the rest are found in other phytopathogenic bacteria. XopF1 and XopF2 define an effector gene family in Xcv. XopN contains a eukaryotic protein fold repeat and is required for full Xcv pathogenicity in pepper and tomato. The translocated effectors identified in this work expand our knowledge of the diversity of proteins that Xcv uses to manipulate its hosts. PMID:15545602

Roden, Julie Anne; Belt, Brandis; Ross, Jason Barzel; Tachibana, Thomas; Vargas, Joe; Mudgett, Mary Beth

2004-11-23

37

Autocrine IL-10 induces hallmarks of alternative activation in macrophages and suppresses anti-tuberculosis effector mechanisms without compromising T cell immunity1  

PubMed Central

Elevated IL-10 has been implicated in reactivation tuberculosis (TB). Since macrophages rather than T cells were reported to be the major source of IL-10 in TB, we analyzed the consequences of a macrophage-specific overexpression of IL-10 in transgenic mice (macIL-10-transgenic) after aerosol infection with Mycobacterium tuberculosis (Mtb). MacIL-10-transgenic mice were more susceptible to chronic Mtb infection than non-transgenic littermates, exhibiting higher bacterial loads in the lung after 12 weeks of infection and dying significantly earlier than controls. The differentiation, recruitment and activation of TH1 cells as well as the induction of IFN-gamma-dependent effector genes against Mtb were not affected by macrophage-derived IL-10. However, microarray analysis of pulmonary gene expression revealed patterns characteristic of alternative macrophage activation that were overrepresented in Mtb-infected macIL-10-transgenic mice. Importantly, arginase-1 gene expression and activity were strikingly enhanced in transgenic mice accompanied by a reduced production of reactive nitrogen intermediates. Moreover, IL-10-dependent arginase-1 induction diminished anti-mycobacterial effector mechanisms in macrophages. Together, macrophage-derived IL-10 triggers aspects of alternative macrophage activation and promotes Mtb recrudescence independent of overt effects on anti-TB T cell immunity. PMID:19561100

Schreiber, Tanja; Ehlers, Stefan; Heitmann, Lisa; Rausch, Alexandra; Mages, Jörg; Murray, Peter J.; Lang, Roland; Hölscher, Christoph

2009-01-01

38

Antigen-specific splenic CD4+ and CD8+ regulatory T cells generated via the eye, suppress Experimental Autoimmune Encephalomyelitis either at the priming or at the effector phase  

PubMed Central

The injection of antigen into the ocular anterior chamber (AC) induces the generation of splenic CD4+ and CD8+ regulatory T (Treg) cells, specific for the antigen injected into the AC. These Treg cells inhibit the induction (CD4+) and also the expression (CD8+) of a delayed-type hypersensitivity response. The ability of AC-induced self-antigen-specific Treg cells in modulating autoimmunity is not well defined. Here we show that an injection of encephalitogenic myelin oligodendrocyte glycoprotein (MOG35–55) peptide into the anterior chamber of the eye (AC-MOG), before the induction of or during established experimental autoimmune encephalomyelitis (EAE) induced by MOG35–55, suppresses the induction or progression of EAE, respectively. CD4+ or CD8+ splenic Treg cells induced by an injection of AC-MOG prevent EAE either at the inductive (priming) or at the progressive (effector) phase, respectively. This suppression of EAE by an AC-MOG injection or by intravenous transfer of splenic regulatory cells induced by an AC-MOG injection is specific for the antigen injected into the AC. Additionally, our data suggest that splenic CD8+ Treg cells that suppress active EAE may use a transforming growth factor (TGF)-?-dependent suppression mechanism while the suppression of the induction of EAE by the AC-induced CD4+ Treg cells is independent of TGF-?. Thus, we show for the first time that regulation of EAE at the priming or the chronic phase requires different phenotypes of Treg cells. Hence, it is important to consider the phenotype of Treg cells while designing effective cell-based therapies against autoimmune disorders. PMID:21273399

Bhowmick, Sourojit; Clark, Robert B.; Brocke, Stefan

2011-01-01

39

Fungal effector proteins: past, present and future.  

PubMed

The pioneering research of Harold Flor on flax and the flax rust fungus culminated in his gene-for-gene hypothesis. It took nearly 50 years before the first fungal avirulence (Avr) gene in support of his hypothesis was cloned. Initially, fungal Avr genes were identified by reverse genetics and map-based cloning from model organisms, but, currently, the availability of many sequenced fungal genomes allows their cloning from additional fungi by a combination of comparative and functional genomics. It is believed that most Avr genes encode effectors that facilitate virulence by suppressing pathogen-associated molecular pattern-triggered immunity and induce effector-triggered immunity in plants containing cognate resistance proteins. In resistant plants, effectors are directly or indirectly recognized by cognate resistance proteins that reside either on the plasma membrane or inside the plant cell. Indirect recognition of an effector (also known as the guard model) implies that the virulence target of an effector in the host (the guardee) is guarded by the resistance protein (the guard) that senses manipulation of the guardee, leading to activation of effector-triggered immunity. In this article, we review the literature on fungal effectors and some pathogen-associated molecular patterns, including those of some fungi for which no gene-for-gene relationship has been established. PMID:19849781

De Wit, Pierre J G M; Mehrabi, Rahim; Van den Burg, Harrold A; Stergiopoulos, Ioannis

2009-11-01

40

Functional Analysis of Hyaloperonospora arabidopsidis RXLR Effectors  

PubMed Central

The biotrophic plant pathogen Hyaloperonospora arabidopsidis produces a set of putative effector proteins that contain the conserved RXLR motif. For most of these RXLR proteins the role during infection is unknown. Thirteen RXLR proteins from H. arabidopsidis strain Waco9 were analyzed for sequence similarities and tested for a role in virulence. The thirteen RXLR proteins displayed conserved N-termini and this N-terminal conservation was also found in the 134 predicted RXLR genes from the genome of H. arabidopsidis strain Emoy2. To investigate the effects of single RXLR effector proteins on plant defense responses, thirteen H. arabidopsidis Waco9 RXLR genes were expressed in Arabidopsis thaliana. Subsequently, these plants were screened for altered susceptibility to the oomycetes H. arabidopsidis and Phytophthora capsici, and the bacterial pathogen Pseudomonas syringae. Additionally, the effect of the RXLR proteins on flg22-triggered basal immune responses was assessed. Multifactorial analysis of results collated from all experiments revealed that, except for RXLR20, all RXLR effector proteins tested affected plant immunity. For RXLR9 this was confirmed using a P. syringae ?CEL-mediated effector delivery system. Together, the results show that many H. arabidopsidis RXLR effectors have small effects on the plant immune response, suggesting that suppression of host immunity by this biotrophic pathogen is likely to be caused by the combined actions of effectors. PMID:25375163

Pel, Michiel J. C.; Wintermans, Paul C. A.; Cabral, Adriana; Robroek, Bjorn J. M.; Seidl, Michael F.; Bautor, Jaqueline; Parker, Jane E.; Van den Ackerveken, Guido; Pieterse, Corné M. J.

2014-01-01

41

End-effector microprocessor  

NASA Technical Reports Server (NTRS)

The topics are presented in viewgraph form and include: automated structures assembly facility current control hierarchy; automated structures assembly facility purposed control hierarchy; end-effector software state transition diagram; block diagram for ideal install composite; and conclusions.

Doggett, William R.

1992-01-01

42

Transcriptional Programming and Functional Interactions within the Phytophthora sojae RXLR Effector Repertoire[C][W][OA  

PubMed Central

The genome of the soybean pathogen Phytophthora sojae contains nearly 400 genes encoding candidate effector proteins carrying the host cell entry motif RXLR-dEER. Here, we report a broad survey of the transcription, variation, and functions of a large sample of the P. sojae candidate effectors. Forty-five (12%) effector genes showed high levels of polymorphism among P. sojae isolates and significant evidence for positive selection. Of 169 effectors tested, most could suppress programmed cell death triggered by BAX, effectors, and/or the PAMP INF1, while several triggered cell death themselves. Among the most strongly expressed effectors, one immediate-early class was highly expressed even prior to infection and was further induced 2- to 10-fold following infection. A second early class, including several that triggered cell death, was weakly expressed prior to infection but induced 20- to 120-fold during the first 12 h of infection. The most strongly expressed immediate-early effectors could suppress the cell death triggered by several early effectors, and most early effectors could suppress INF1-triggered cell death, suggesting the two classes of effectors may target different functional branches of the defense response. In support of this hypothesis, misexpression of key immediate-early and early effectors severely reduced the virulence of P. sojae transformants. PMID:21653195

Wang, Qunqing; Han, Changzhi; Ferreira, Adriana O.; Yu, Xiaoli; Ye, Wenwu; Tripathy, Sucheta; Kale, Shiv D.; Gu, Biao; Sheng, Yuting; Sui, Yangyang; Wang, Xiaoli; Zhang, Zhengguang; Cheng, Baoping; Dong, Suomeng; Shan, Weixing; Zheng, Xiaobo; Dou, Daolong; Tyler, Brett M.; Wang, Yuanchao

2011-01-01

43

Robotic end effector  

DOEpatents

An end effector is described for use in probing a surface with a robotic arm. The end effector has a first portion that carries a gimbal with a probe, the gimbal holding the probe normal to the surface, and a second portion with a set of three shafts within a housing for urging the gimbal and probe against the surface. The second portion contains a potentiometer connected by another shaft to the first portion to measure the position of the first portion with respect to the second so that the second portion can be moved to place and maintain the shafts at the midpoint of their travel. Then, as irregularities in the surface are encountered, the first portion can respond by moving closer to or farther from the second portion. 7 figures.

Minichan, R.L.

1993-10-05

44

Robotic end effector  

DOEpatents

An end effector for use in probing a surface with a robotic arm. The end effector has a first portion that carries a gimbal with a probe, the gimbal holding the probe normal to the surface, and a second portion with a set of three shafts within a housing for urging the gimbal and probe against the surface. The second portion contains a potentiometer connected by another shaft to the first portion to measure the position of the first portion with respect to the second so that the second portion can be moved to place and maintain the shafts at the midpoint of their travel. Then, as irregularities in the surface are encountered, the first portion can respond by moving closer to or farther from the second portion.

Minichan, Richard L. (23 Pineview Dr., Warrenville, SC 29851)

1993-01-01

45

G Protein Effectors  

NSDL National Science Digital Library

This Teaching Resource provides lecture notes and slides for a class covering two aspects of G protein–mediated signaling and is part of the course "Cell Signaling Systems: A Course for Graduate Students." The lecture begins with a discussion of the regulation of receptor-G protein coupling and then proceeds to describe the specificity of the response achieved through regulation of specific isoforms of effectors.

Maria Diverse-Pierluissi (Mount Sinai School of Medicine; Department of Pharmacology and Biological Chemistry REV)

2005-04-26

46

The haustorial transcriptomes of Uromyces appendiculatus and Phakopsora pachyrhizi and their candidate effector families  

Technology Transfer Automated Retrieval System (TEKTRAN)

The haustoria of the biotrophic rust fungi are responsible for the uptake of nutrients from host cells, and they produce secreted proteins known as effectors that suppress host defenses. Effectors hold essential keys for elucidating the plant-fungal interactions, and they are promising targets for p...

47

T Cell Signaling Targets for Enhancing Regulatory or Effector Function  

NSDL National Science Digital Library

To respond to infection, resting or naïve T cells must undergo activation, clonal expansion, and differentiation into specialized functional subsets of effector T cells. However, to prevent excessive or self-destructive immune responses, regulatory T cells (Tregs) are instrumental in suppressing the activation and function of effector cells, including effector T cells. The transcription factor Forkhead box P3 (Foxp3) regulates the expression of genes involved in the development and function of Tregs. Foxp3 interacts with other transcription factors and with epigenetic elements such as histone deacetylases (HDACs) and histone acetyltransferases. Treg suppressive function can be increased by exposure to HDAC inhibitors. The individual contributions of different HDAC family members to Treg function and their respective mechanisms of action, however, remain unclear. A study showed that HDAC6, HDAC9, and Sirtuin-1 had distinct effects on Foxp3 expression and function, suggesting that selectively targeting HDACs individually or in combination may enhance Treg stability and suppressive function. Another study showed that the receptor programmed death 1 (PD-1), a well-known inhibitor of T cell activation, halted cell cycle progression in effector T cells by inhibiting the transcription of the gene encoding the substrate-recognition component (Skp2) of the ubiquitin ligase SCFSkp2. Together, these findings reveal new signaling targets for enhancing Treg or effector T cell function that may be helpful in designing future therapies, either to increase Treg suppressive function in transplantation and autoimmune diseases or to block PD-1 function, thus increasing the magnitude of antiviral or antitumor immune responses of effector T cells.

Fan Pan (Johns Hopkins University School of Medicine;Department of Oncology REV); Huimin Fan (Shanghai;Shanghai East Hospital of Tongji University REV); Zhongmin Liu (Shanghai;Shanghai East Hospital of Tongji University REV); Shuiping Jiang (Shanghai;Shanghai East Hospital of Tongji University REV)

2012-07-31

48

Two-axis angular effector  

DOEpatents

A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.

Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)

1997-01-21

49

Sequential Delivery of Host-Induced Virulence Effectors by Appressoria and Intracellular Hyphae of the Phytopathogen Colletotrichum higginsianum  

PubMed Central

Phytopathogens secrete effector proteins to manipulate their hosts for effective colonization. Hemibiotrophic fungi must maintain host viability during initial biotrophic growth and elicit host death for subsequent necrotrophic growth. To identify effectors mediating these opposing processes, we deeply sequenced the transcriptome of Colletotrichum higginsianum infecting Arabidopsis. Most effector genes are host-induced and expressed in consecutive waves associated with pathogenic transitions, indicating distinct effector suites are deployed at each stage. Using fluorescent protein tagging and transmission electron microscopy-immunogold labelling, we found effectors localised to stage-specific compartments at the host-pathogen interface. In particular, we show effectors are focally secreted from appressorial penetration pores before host invasion, revealing new levels of functional complexity for this fungal organ. Furthermore, we demonstrate that antagonistic effectors either induce or suppress plant cell death. Based on these results we conclude that hemibiotrophy in Colletotrichum is orchestrated through the coordinated expression of antagonistic effectors supporting either cell viability or cell death. PMID:22496661

Kleemann, Jochen; Neumann, Ulla; van Themaat, Emiel Ver Loren; van der Does, H. Charlotte; Hacquard, Stéphane; Stüber, Kurt; Will, Isa; Schmalenbach, Wolfgang; Schmelzer, Elmon; O'Connell, Richard J.

2012-01-01

50

Effector Glycosyltransferases in Legionella  

PubMed Central

Legionella causes severe pneumonia in humans. The pathogen produces an array of effectors, which interfere with host cell functions. Among them are the glucosyltransferases Lgt1, Lgt2 and Lgt3 from L. pneumophila. Lgt1 and Lgt2 are produced predominately in the post-exponential phase of bacterial growth, while synthesis of Lgt3 is induced mainly in the lag-phase before intracellular replication of bacteria starts. Lgt glucosyltransferases are structurally similar to clostridial glucosylating toxins. The enzymes use UDP–glucose as a donor substrate and modify eukaryotic elongation factor eEF1A at serine-53. This modification results in inhibition of protein synthesis and death of target cells.In addition to Lgts, Legionella genomes disclose several genes, coding for effector proteins likely to possess glycosyltransferase activities, including SetA (subversion of eukaryotic vesicle trafficking A), which influences vesicular trafficking in the yeast model system and displays tropism for late endosomal/lysosomal compartments of mammalian cells. This review mainly discusses recent results on the structure–function relationship of Lgt glucosyltransferases. PMID:21833323

Belyi, Yury; Jank, Thomas; Aktories, Klaus

2011-01-01

51

Suppression of development of anti-nuclear antibody and glomerulonephritis in NZB x NZWF1 mice by persistent infection with lactic dehydrogenase virus: possible involvement of superoxide anion as a progressive effector.  

PubMed Central

The development of anti-nuclear antibody (ANA) and glomerulonephritis (GN) in autoimmune NZB x NZWF1 mice was suppressed by persistent lactic dehydrogenase virus (LDV) infection. This observation was used to study a possible pathogenetic role for the toxic oxygen radical, superoxide anion (O2-), in the progression of ANA and GN. Compared to macrophages from NZB x NZWF1 mice with LDV infection, macrophages from uninfected NZB x NZWF1 mice exhibited an age-related and drastic increase in O2- production in association with the development of the ANA and GN (representing the late stage of disease). NZB x NZWF1 mice with or without LDV infection were then given the O2- scavenger superoxide dismutase (SOD) during the late stage of the disease. Treatment of uninfected NZB x NZWF1 mice with SOD (10,000 units/mouse/day for 3 weeks) protected animals from the development of ANA and GN. SOD treatment also suppressed the development of the lesions in NZB x NZWF1 mice with LDV infection. Our findings suggest that O2- may, at least in part, contribute to the development of ANA and GN in the late stage of disease, and that decreased O2- production in NZB x NZWF1 mice with LDV infection may be responsible for the suppression of the development of ANA and GN in the late stage of the disease. Images Figure 7 Figure 9 PMID:8292553

Hayashi, T.; Noguchi, Y.; Kameyama, Y.

1993-01-01

52

RAR1, a Central Player in Plant Immunity, is Targeted by Pseudomonas syringae Effector AvrB  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pathogenic bacterial effectors suppress Pathogen-Associated Molecular Pattern (PAMP)-triggered host immunity, thereby promoting parasitism. In the presence of cognate resistance genes, it is proposed that plants detect the virulence activity of bacterial effectors and trigger a defense response, ref...

53

Oomycetes, effectors, and all that jazz.  

PubMed

Plant pathogenic oomycetes secrete a diverse repertoire of effector proteins that modulate host innate immunity and enable parasitic infection. Understanding how effectors evolve, translocate and traffic inside host cells, and perturb host processes are major themes in the study of oomycete-plant interactions. The last year has seen important progress in the study of oomycete effectors with, notably, the elucidation of the 3D structures of five RXLR effectors, and novel insights into how cytoplasmic effectors subvert host cells. In this review, we discuss these and other recent advances and highlight the most important open questions in oomycete effector biology. PMID:22483402

Bozkurt, Tolga O; Schornack, Sebastian; Banfield, Mark J; Kamoun, Sophien

2012-08-01

54

The type III effectors of Xanthomonas.  

PubMed

A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence and structural similarity searches of genomic data. We propose that the effectors and suspected effectors should be distributed into 39 so-called Xop groups reflecting sequence similarity. Some groups have structural motifs for putative enzymatic functions, and recent studies have provided considerable insight into the interaction with host factors in their function as mediators of virulence and elicitors of resistance for a few specific T3 effectors. Many groups are related to T3 effectors of plant and animal pathogenic bacteria, and several groups appear to have been exploited primarily by Xanthomonas species based on available data. At the same time, a relatively large number of candidate effectors remain to be examined in more detail with regard to their function within host cells. PMID:19849782

White, Frank F; Potnis, Neha; Jones, Jeffrey B; Koebnik, Ralf

2009-11-01

55

Marker for type VI secretion system effectors  

PubMed Central

Bacteria use diverse mechanisms to kill, manipulate, and compete with other cells. The recently discovered type VI secretion system (T6SS) is widespread in bacterial pathogens and used to deliver virulence effector proteins into target cells. Using comparative proteomics, we identified two previously unidentified T6SS effectors that contained a conserved motif. Bioinformatic analyses revealed that this N-terminal motif, named MIX (marker for type six effectors), is found in numerous polymorphic bacterial proteins that are primarily located in the T6SS genome neighborhood. We demonstrate that several MIX-containing proteins are T6SS effectors and that they are not required for T6SS activity. Thus, we propose that MIX-containing proteins are T6SS effectors. Our findings allow for the identification of numerous uncharacterized T6SS effectors that will undoubtedly lead to the discovery of new biological mechanisms. PMID:24927539

Salomon, Dor; Kinch, Lisa N.; Trudgian, David C.; Guo, Xiaofeng; Klimko, John A.; Grishin, Nick V.; Mirzaei, Hamid; Orth, Kim

2014-01-01

56

Structure and evolution of barley powdery mildew effector candidates  

PubMed Central

Background Protein effectors of pathogenicity are instrumental in modulating host immunity and disease resistance. The powdery mildew pathogen of grasses Blumeria graminis causes one of the most important diseases of cereal crops. B. graminis is an obligate biotrophic pathogen and as such has an absolute requirement to suppress or avoid host immunity if it is to survive and cause disease. Results Here we characterise a superfamily predicted to be the full complement of Candidates for Secreted Effector Proteins (CSEPs) in the fungal barley powdery mildew parasite B. graminis f.sp. hordei. The 491 genes encoding these proteins constitute over 7% of this pathogen’s annotated genes and most were grouped into 72 families of up to 59 members. They were predominantly expressed in the intracellular feeding structures called haustoria, and proteins specifically associated with the haustoria were identified by large-scale mass spectrometry-based proteomics. There are two major types of effector families: one comprises shorter proteins (100–150 amino acids), with a high relative expression level in the haustoria and evidence of extensive diversifying selection between paralogs; the second type consists of longer proteins (300–400 amino acids), with lower levels of differential expression and evidence of purifying selection between paralogs. An analysis of the predicted protein structures underscores their overall similarity to known fungal effectors, but also highlights unexpected structural affinities to ribonucleases throughout the entire effector super-family. Candidate effector genes belonging to the same family are loosely clustered in the genome and are associated with repetitive DNA derived from retro-transposons. Conclusions We employed the full complement of genomic, transcriptomic and proteomic analyses as well as structural prediction methods to identify and characterize the members of the CSEPs superfamily in B. graminis f.sp. hordei. Based on relative intron position and the distribution of CSEPs with a ribonuclease-like domain in the phylogenetic tree we hypothesize that the associated genes originated from an ancestral gene, encoding a secreted ribonuclease, duplicated successively by repetitive DNA-driven processes and diversified during the evolution of the grass and cereal powdery mildew lineage. PMID:23231440

2012-01-01

57

The role of effectors in nonhost resistance to filamentous plant pathogens  

PubMed Central

In nature, most plants are resistant to a wide range of phytopathogens. However, mechanisms contributing to this so-called nonhost resistance (NHR) are poorly understood. Besides constitutive defenses, plants have developed two layers of inducible defense systems. Plant innate immunity relies on recognition of conserved pathogen-associated molecular patterns (PAMPs). In compatible interactions, pathogenicity effector molecules secreted by the invader can suppress host defense responses and facilitate the infection process. Additionally, plants have evolved pathogen-specific resistance mechanisms based on recognition of these effectors, which causes secondary defense responses. The current effector-driven hypothesis is that NHR in plants that are distantly related to the host plant is triggered by PAMP recognition that cannot be efficiently suppressed by the pathogen, whereas in more closely related species, nonhost recognition of effectors would play a crucial role. In this review we give an overview of current knowledge of the role of effector molecules in host and NHR and place these findings in the context of the model. We focus on examples from filamentous pathogens (fungi and oomycetes), discuss their implications for the field of plant-pathogen interactions and relevance in plant breeding strategies for development of durable resistance in crops. PMID:25426123

Stam, Remco; Mantelin, Sophie; McLellan, Hazel; Thilliez, Gaëtan

2014-01-01

58

Plant targets for Pseudomonas syringae type III effectors: Virulence targets or guarded decoys?  

PubMed Central

The phytopathogenic bacterium Pseudomonas syringae can suppress both pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) by the injection of type III effector (T3E) proteins into host cells. T3Es achieve immune suppression using a variety of strategies including interference with immune receptor signaling, blocking RNA pathways and vesicle trafficking, and altering organelle function. T3Es can be recognized directly or indirectly by resistance proteins monitoring specific T3E targets resulting in ETI. It is presently unclear whether the monitored targets represent bona fide virulence targets or guarded decoys. Extensive overlap between PTI and ETI signaling suggests that T3Es may suppress both pathways through common targets and by possessing multiple activities. PMID:21227738

Block, Anna; Alfano, James R.

2011-01-01

59

Deciphering and Reversing Tumor Immune Suppression  

PubMed Central

Generating an anti-tumor immune response is a multi-step process that is executed by effector T cells that can recognize and kill tumor targets. However, tumors employ multiple strategies to attenuate the effectiveness of T cell-mediated attack. This is achieved by interfering with nearly every step required for effective immunity, from deregulation of antigen-presenting cells, to establishment of a physical barrier at the vasculature that prevents homing of effector tumor-rejecting cells, and through the suppression of effector lymphocytes through the recruitment and activation of immunosuppressive cells like myeloid-derived suppressor cells (MDSCs), tolerogenic monocytes and T regulatory cells (Tregs). Here, we review the ways in which tumors exert immune suppression and highlight the new therapies that seek to reverse this phenomenon and promote anti-tumor immunity. Understanding anti-tumor immunity, and how it becomes disabled by tumors, will ultimately lead to improved immune therapies and prolonged survival of patients. PMID:23890064

Motz, Greg T.; Coukos, George

2013-01-01

60

ROBOTIC TANK INSPECTION END EFFECTOR  

SciTech Connect

The objective of this contract between Oceaneering Space Systems (OSS) and the Department of Energy (DOE) was to provide a tool for the DOE to inspect the inside tank walls of underground radioactive waste storage tanks in their tank farms. Some of these tanks are suspected to have leaks, but the harsh nature of the environment within the tanks precludes human inspection of tank walls. As a result of these conditions only a few inspection methods can fulfill this task. Of the methods available, OSS chose to pursue Alternating Current Field Measurement (ACFM), because it does not require clean surfaces for inspection, nor any contact with the Surface being inspected, and introduces no extra by-products in the inspection process (no coupling fluids or residues are left behind). The tool produced by OSS is the Robotic Tank Inspection End Effector (RTIEE), which is initially deployed on the tip of the Light Duty Utility Arm (LDUA). The RTEE combines ACFM with a color video camera for both electromagnetic and visual inspection The complete package consists of an end effector, its corresponding electronics and software, and a user's manual to guide the operator through an inspection. The system has both coarse and fine inspection modes and allows the user to catalog defects and suspected areas of leakage in a database for further examination, which may lead to emptying the tank for repair, decommissioning, etc.. The following is an updated report to OSS document OSS-21100-7002, which was submitted in 1995. During the course of the contract, two related subtasks arose, the Wall and Coating Thickness Sensor and the Vacuum Scarifying and Sampling Tool Assembly. The first of these subtasks was intended to evaluate the corrosion and wall thinning of 55-gallon steel drums. The second was retrieved and characterized the waste material trapped inside the annulus region of the underground tanks on the DOE's tank farms. While these subtasks were derived from the original intent of the contract, the focus remains on the RTIEE.

Rachel Landry

1999-10-01

61

Pentoxifylline Suppresses Irritant and Contact Hypersensitivity Reactions  

Microsoft Academic Search

Pharmacologic suppression of the effector phase ot contact hypersensitivity appears to have major relevance with regard to treatment of type IV reactions like contact dermatitis. Recently, tumor necrosis factor ? has been shown to be a critical mediator in hapten-induced irritant and contact hypersensitivity reactions, thus offering new possibilities, for therapeutic intervention. Pentoxifylline, a methylxanthine derivative used in the treatment

Agatha Schwarz; Christine Krone; Franz Trautinger; Yoshinori Aragane; Peter Neuner; Thomas A. Luger; Thomas Schwarz

1993-01-01

62

Oxysterols and Their Cellular Effectors  

PubMed Central

Oxysterols are oxidized 27-carbon cholesterol derivatives or by-products of cholesterol biosynthesis, with a spectrum of biologic activities. Several oxysterols have cytotoxic and pro-apoptotic activities, the ability to interfere with the lateral domain organization, and packing of membrane lipids. These properties may account for their suggested roles in the pathology of diseases such as atherosclerosis, age-onset macular degeneration and Alzheimer’s disease. Oxysterols also have the capacity to induce inflammatory responses and play roles in cell differentiation processes. The functions of oxysterols as intermediates in the synthesis of bile acids and steroid hormones, and as readily transportable forms of sterol, are well established. Furthermore, their actions as endogenous regulators of gene expression in lipid metabolism via liver X receptors and the Insig (insulin-induced gene) proteins have been investigated in detail. The cytoplasmic oxysterol-binding protein (OSBP) homologues form a group of oxysterol/cholesterol sensors that has recently attracted a lot of attention. However, their mode of action is, as yet, poorly understood. Retinoic acid receptor-related orphan receptors (ROR) ? and ?, and Epstein-Barr virus induced gene 2 (EBI2) have been identified as novel oxysterol receptors, revealing new physiologic oxysterol effector mechanisms in development, metabolism, and immunity, and evoking enhanced interest in these compounds in the field of biomedicine. PMID:24970128

Olkkonen, Vesa M.; Béaslas, Olivier; Nissilä, Eija

2012-01-01

63

A TAL Effector Toolbox for Genome Engineering  

E-print Network

Transcription activator-like effectors (TALEs) are a class of naturally occurring DNA-binding proteins found in the plant pathogen Xanthomonas sp. The DNA-binding domain of each TALE consists of tandem 34–amino acid repeat ...

Sanjana, Neville E.

64

Advances in experimental methods for the elucidation of Pseudomonas syringae effector function with a focus on AvrPtoB  

PubMed Central

SUMMARY Pseudomonas syringae infects a wide range of plant species through the use of a type III secretion system. The effector proteins injected into the plant cell through this molecular syringe serve as promoters of disease by subverting the plant immune response to the benefit of the bacteria in the intercellular space. The targets and activities of a subset of effectors have been elucidated recently. In this article, we focus on the experimental approaches that have proved most successful in probing the molecular basis of effectors, ranging from loss-of-function to gain-of-function analyses utilizing several techniques for effector delivery into plants. In particular, we highlight how these diverse approaches have been applied to the study of one effector—AvrPtoB—a multifunctional protein with the ability to suppress both effector-triggered immunity and pathogen (or microbe)-associated molecular pattern-triggered immunity. Taken together, advances in this field illustrate the need for multiple experimental approaches when elucidating the function of a single effector. PMID:19849784

Munkvold, Kathy R.; Martin, Gregory B.

2010-01-01

65

Jet Engine Exhaust Nozzle Flow Effector  

NASA Technical Reports Server (NTRS)

A jet engine exhaust nozzle flow effector is a chevron formed with a radius of curvature with surfaces of the flow effector being defined and opposing one another. At least one shape memory alloy (SMA) member is embedded in the chevron closer to one of the chevron's opposing surfaces and substantially spanning from at least a portion of the chevron's root to the chevron's tip.

Turner, Travis L. (Inventor); Cano, Roberto J. (Inventor); Silcox, Richard J. (Inventor); Buehrle, Ralph D. (Inventor); Cagle, Christopher M. (Inventor); Cabell, Randolph H. (Inventor); Hilton, George C. (Inventor)

2011-01-01

66

The Salmonella effector protein SpvC, a phosphothreonine lyase is functional in plant cells  

PubMed Central

Salmonella is one of the most prominent causes of food poisoning and growing evidence indicates that contaminated fruits and vegetables are an increasing concern for human health. Successful infection demands the suppression of the host immune system, which is often achieved via injection of bacterial effector proteins into host cells. In this report we present the function of Salmonella effector protein in plant cell, supporting the new concept of trans-kingdom competence of this bacterium. We screened a range of Salmonella Typhimurium effector proteins for interference with plant immunity. Among these, the phosphothreonine lyase SpvC attenuated the induction of immunity-related genes when present in plant cells. Using in vitro and in vivo systems we show that this effector protein interacts with and dephosphorylates activated Arabidopsis Mitogen-activated Protein Kinase 6 (MPK6), thereby inhibiting defense signaling. Moreover, the requirement of Salmonella SpvC was shown by the decreased proliferation of the ?spvC mutant in Arabidopsis plants. These results suggest that some Salmonella effector proteins could have a conserved function during proliferation in different hosts. The fact that Salmonella and other Enterobacteriaceae use plants as hosts strongly suggests that plants represent a much larger reservoir for animal pathogens than so far estimated. PMID:25368608

Neumann, Christina; Fraiture, Malou; Hernàndez-Reyes, Casandra; Akum, Fidele N.; Virlogeux-Payant, Isabelle; Chen, Ying; Pateyron, Stephanie; Colcombet, Jean; Kogel, Karl-Heinz; Hirt, Heribert; Brunner, Frédéric; Schikora, Adam

2014-01-01

67

The protein kinase A anchoring protein mAKAP coordinates two integrated cAMP effector pathways  

E-print Network

The protein kinase A anchoring protein mAKAP coordinates two integrated cAMP effector pathwaysAMP-responsive signalling complex maintained by the muscle- specific A-kinase anchoring protein (mAKAP) that includes PKA, whereas an mAKAP-associated ERK5 kinase module suppresses PDE4D3. PDE4D3 also functions as an adaptor

Scott, John D.

68

TAL effectors: tools for DNA Targeting  

PubMed Central

Xanthomonas phytopathogenic bacteria produce unique transcription activator-like effector (TALE) proteins that recognize and activate specific plant promoters through a set of tandem repeats. A unique TALE-DNA-binding code uses two polymorphic amino acids in each repeat to mediate recognition of specific nucleotides. The order of repeats determines effector’s specificity toward the cognate nucleotide sequence of the sense DNA strand. Artificially designed TALE-DNA-binding domains fused to nuclease or activation and repressor domains provide an outstanding toolbox for targeted gene editing and gene regulation in research, biotechnology and gene therapy. Gene editing with custom-designed TALE nucleases (TALENs) extends the repertoire of targeted genome modifications across a broad spectrum of organisms ranging from plants and insect to mammals. PMID:24907364

Jankele, Radek

2014-01-01

69

Identification of candidate effector genes in the transcriptome of the rice root knot nematode Meloidogyne graminicola.  

PubMed

Plant-parasitic nematodes secrete so-called effectors into their host plant which are able to suppress the plant's defence responses, alter plant signalling pathways and, in the case of root knot nematodes, induce the formation of giant cells. Putative effectors have been successfully identified by genomics, transcriptomics and proteomics approaches. In this study, we investigated the transcriptome of the rice root knot nematode Meloidogyne graminicola by 454 sequencing of second-stage juveniles as well as mRNA-seq of rice infected tissue. Over 350?000 reads derived from M.?graminicola preparasitic juveniles were assembled, annotated and checked for homologues in different databases. From infected rice tissue, 1.4% of all reads generated were identified as being derived from the nematode. Using multiple strategies, several putative effector genes were identified, both pioneer genes and genes corresponding to already known effectors. To check whether these genes could be involved in the interaction with the plant, in?situ hybridization was performed on a selection of genes to localize their expression in the nematode. Most were expressed in the gland cells or amphids of the nematode, confirming possible secretion of the proteins and hence a role in infection. Other putative effectors showed a different expression pattern, potentially linked with the excretory/secretory system. This transcriptome study is a good starting point to functionally investigate novel effectors derived from M.?graminicola. This will lead to better insights into the interaction between these nematodes and the model plant rice. Moreover, the transcriptome can be used to identify possible target genes for RNA interference (RNAi)-based control strategies. Four genes proved to be interesting targets by showing up to 40% higher mortality relative to the control treatment when soaked in gene-specific small interfering RNAs (siRNAs). PMID:23279209

Haegeman, Annelies; Bauters, Lander; Kyndt, Tina; Rahman, Mohammad Masuder; Gheysen, Godelieve

2013-05-01

70

Gene Duplication and Fragment Recombination Drive Functional Diversification of a Superfamily of Cytoplasmic Effectors in Phytophthora sojae  

PubMed Central

Phytophthora and other oomycetes secrete a large number of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling and necrosis inducing proteins (CRN), or Crinkler. Here, we first investigated the evolutionary patterns and mechanisms of CRN effectors in Phytophthora sojae and compared them to two other Phytophthora species. The genes encoding CRN effectors could be divided into 45 orthologous gene groups (OGG), and most OGGs unequally distributed in the three species, in which each underwent large number of gene gains or losses, indicating that the CRN genes expanded after species evolution in Phytophthora and evolved through pathoadaptation. The 134 expanded genes in P. sojae encoded family proteins including 82 functional genes and expressed at higher levels while the other 68 genes encoding orphan proteins were less expressed and contained 50 pseudogenes. Furthermore, we demonstrated that most expanded genes underwent gene duplication or/and fragment recombination. Three different mechanisms that drove gene duplication or recombination were identified. Finally, the expanded CRN effectors exhibited varying pathogenic functions, including induction of programmed cell death (PCD) and suppression of PCD through PAMP-triggered immunity or/and effector-triggered immunity. Overall, these results suggest that gene duplication and fragment recombination may be two mechanisms that drive the expansion and neofunctionalization of the CRN family in P. sojae, which aids in understanding the roles of CRN effectors within each oomycete pathogen. PMID:23922898

Shen, Danyu; Liu, Tingli; Ye, Wenwu; Liu, Li; Liu, Peihan; Wu, Yuren; Wang, Yuanchao; Dou, Daolong

2013-01-01

71

Gene duplication and fragment recombination drive functional diversification of a superfamily of cytoplasmic effectors in Phytophthora sojae.  

PubMed

Phytophthora and other oomycetes secrete a large number of putative host cytoplasmic effectors with conserved FLAK motifs following signal peptides, termed crinkling and necrosis inducing proteins (CRN), or Crinkler. Here, we first investigated the evolutionary patterns and mechanisms of CRN effectors in Phytophthora sojae and compared them to two other Phytophthora species. The genes encoding CRN effectors could be divided into 45 orthologous gene groups (OGG), and most OGGs unequally distributed in the three species, in which each underwent large number of gene gains or losses, indicating that the CRN genes expanded after species evolution in Phytophthora and evolved through pathoadaptation. The 134 expanded genes in P. sojae encoded family proteins including 82 functional genes and expressed at higher levels while the other 68 genes encoding orphan proteins were less expressed and contained 50 pseudogenes. Furthermore, we demonstrated that most expanded genes underwent gene duplication or/and fragment recombination. Three different mechanisms that drove gene duplication or recombination were identified. Finally, the expanded CRN effectors exhibited varying pathogenic functions, including induction of programmed cell death (PCD) and suppression of PCD through PAMP-triggered immunity or/and effector-triggered immunity. Overall, these results suggest that gene duplication and fragment recombination may be two mechanisms that drive the expansion and neofunctionalization of the CRN family in P. sojae, which aids in understanding the roles of CRN effectors within each oomycete pathogen. PMID:23922898

Shen, Danyu; Liu, Tingli; Ye, Wenwu; Liu, Li; Liu, Peihan; Wu, Yuren; Wang, Yuanchao; Dou, Daolong

2013-01-01

72

Minimal Mimicry: Mere Effector Matching Induces Preference  

ERIC Educational Resources Information Center

Both mimicking and being mimicked induces preference for a target. The present experiments investigate the minimal sufficient conditions for this mimicry-preference link to occur. We argue that mere effector matching between one's own and the other person's movement is sufficient to induce preference, independent of which movement is actually…

Sparenberg, Peggy; Topolinski, Sascha; Springer, Anne; Prinz, Wolfgang

2012-01-01

73

Complement as effector system in cancer immunotherapy  

Microsoft Academic Search

The contribution of the complement system to the control of tumour growth has been neglected for a long time as the major emphasis has been put mainly on cell-mediated immune response against cancer. With the introduction of monoclonal antibodies in cancer immunotherapy complement has come into play with a great potential as effector system. Complement has a number of advantages

Paolo Macor; Francesco Tedesco

2007-01-01

74

Antibodies targeting human OX40 expand effector T cells and block inducible and natural regulatory T cell function  

PubMed Central

Current cancer vaccines induce tumor-specific T cell responses without sustained tumor regression because immunosuppressive elements within the tumor induce exhaustion of effector T cells and infiltration of immune-suppressive regulatory T cells (Tregs). Therefore, much effort has been made to generate agonistic Abs targeting members of the TNFR superfamily, such as OX40, 4- 1BB, and GITR, expressed on effector T cells and Tregs, to reinvigorate T cell effector function and block Treg-suppressive function. In this article, we describe the development of a panel of anti-human OX40 agonistic mouse mAbs that could promote effector CD4+ and CD8+ T cell proliferation, inhibit the induction of CD4+ IL-10 -producing type 1 regulatory T cells, inhibit the expansion of ICOS+IL-10+ Tregs, inhibit TGF-b–induced FOXP3 expression on naive CD4+ T cells, and block natural Treg–suppressive function. We humanized two anti–human OX40 mAb clones, and they retained the potency of their parental clones. These Abs should provide broad opportunities for potential combination therapy to treat a wide realm of cancers and preventative vaccines against infectious diseases. PMID:24014877

Voo, Kui S.; Bover, Laura; Harline, Megan L.; Vien, Long T.; Facchinetti, Valeria; Arima, Kazuhiko; Kwak, Larry W.; Liu, Yong J.

2013-01-01

75

Lymphokine regulation of macrophage effector activities.  

PubMed

Our concept of the regulation of macrophage activation is ever expanding and contracting. In regard to the number of LK that regulate macrophages killing activities, we have entered a new phase. In the beginning there was one macrophage activation factor, MIF; then there were many macrophage activation factors, most uncharacterized and bearing a variety of names. Then came IFN, a genetically cloned single reagent that induced destruction of virtually every target assessed; all activities of macrophages were assumed to be regulated by IFN. Once again, however, the LK universe is expanding: the number of single, cloned reagents that induce macrophage killing activities is amazing. With just two targets, a fibrosarcoma cell and an intracellular amastigote of L. major, we can identify 5 different macrophage activation factors, four of which are cloned and sequenced. As more recombinant reagents become available, the story of macrophage activation is likely to become even more complex. It is fascinating not only that certain of the LK are capable of inducing single effector reactions in the absence of effects on other effector activities, but also that at least one effector reaction requires the cooperation of several molecularly distinct LK. The complexity of LK activation factors that regulate a single effector reaction in vitro is compounded by the complexity in effector cell populations. For example, inflammatory macrophages exposed to LK kill the fibrosarcoma tumor target 5 to 10-fold better than an equal number of resident peritoneal macrophages. In contrast, LK treated resident macrophages eliminate intracellular amastigotes of leishmania far more efficiently than inflammatory cells. Thus, changes in cell populations dramatically affect the capacity to demonstrate a single effector reaction. Further, simple changes in assay conditions also determine whether an effector reaction can be observed in vitro. And superimposed upon all these layers of complexity is the target itself. The mechanisms a macrophages uses to block the replication of a virus may be totally ineffective in the destruction of a multicellular helminth, such as Schistosoma mansoni. And there is no reason to suspect that the extracellular destruction of a tumor target occurs by the same means that the macrophage uses to kill an intracytoplasmic bacterium, such as a rickettsia.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3059762

Nacy, C A; Belosevic, M; Crawford, R M; Healy, A T; Schreiber, R D; Meltzer, M S

1988-01-01

76

Combover/CG10732, a Novel PCP Effector for Drosophila Wing Hair Formation  

PubMed Central

The polarization of cells is essential for the proper functioning of most organs. Planar Cell Polarity (PCP), the polarization within the plane of an epithelium, is perpendicular to apical-basal polarity and established by the non-canonical Wnt/Fz-PCP signaling pathway. Within each tissue, downstream PCP effectors link the signal to tissue specific readouts such as stereocilia orientation in the inner ear and hair follicle orientation in vertebrates or the polarization of ommatidia and wing hairs in Drosophila melanogaster. Specific PCP effectors in the wing such as Multiple wing hairs (Mwh) and Rho Kinase (Rok) are required to position the hair at the correct position and to prevent ectopic actin hairs. In a genome-wide screen in vitro, we identified Combover (Cmb)/CG10732 as a novel Rho kinase substrate. Overexpression of Cmb causes the formation of a multiple hair cell phenotype (MHC), similar to loss of rok and mwh. This MHC phenotype is dominantly enhanced by removal of rok or of other members of the PCP effector gene family. Furthermore, we show that Cmb physically interacts with Mwh, and cmb null mutants suppress the MHC phenotype of mwh alleles. Our data indicate that Cmb is a novel PCP effector that promotes to wing hair formation, a function that is antagonized by Mwh. PMID:25207969

Fagan, Jeremy K.; Dollar, Gretchen; Lu, Qiuheng; Barnett, Austen; Pechuan Jorge, Joaquin; Schlosser, Andreas; Pfleger, Cathie; Adler, Paul; Jenny, Andreas

2014-01-01

77

Combover/CG10732, a novel PCP effector for Drosophila wing hair formation.  

PubMed

The polarization of cells is essential for the proper functioning of most organs. Planar Cell Polarity (PCP), the polarization within the plane of an epithelium, is perpendicular to apical-basal polarity and established by the non-canonical Wnt/Fz-PCP signaling pathway. Within each tissue, downstream PCP effectors link the signal to tissue specific readouts such as stereocilia orientation in the inner ear and hair follicle orientation in vertebrates or the polarization of ommatidia and wing hairs in Drosophila melanogaster. Specific PCP effectors in the wing such as Multiple wing hairs (Mwh) and Rho Kinase (Rok) are required to position the hair at the correct position and to prevent ectopic actin hairs. In a genome-wide screen in vitro, we identified Combover (Cmb)/CG10732 as a novel Rho kinase substrate. Overexpression of Cmb causes the formation of a multiple hair cell phenotype (MHC), similar to loss of rok and mwh. This MHC phenotype is dominantly enhanced by removal of rok or of other members of the PCP effector gene family. Furthermore, we show that Cmb physically interacts with Mwh, and cmb null mutants suppress the MHC phenotype of mwh alleles. Our data indicate that Cmb is a novel PCP effector that promotes to wing hair formation, a function that is antagonized by Mwh. PMID:25207969

Fagan, Jeremy K; Dollar, Gretchen; Lu, Qiuheng; Barnett, Austen; Pechuan Jorge, Joaquin; Schlosser, Andreas; Pfleger, Cathie; Adler, Paul; Jenny, Andreas

2014-01-01

78

Impact of end effector technology on telemanipulation performance  

NASA Technical Reports Server (NTRS)

Generic requirements for end effector design are briefly summarized as derived from generic functional and operational requirements. Included is a brief summary of terms and definitions related to end effector technology. The second part contains a brief overview of end effector technology work as JPL during the past ten years, with emphasis on the evolution of new mechanical, sensing and control capabilities of end effectors. The third and major part is devoted to the description of current end effector technology. The ongoing work addresses mechanical, sensing and control details with emphasis on mechanical ruggedness, increased resolution in sensing, and close electronic and control integration with overall telemanipulator control system.

Bejczy, A. K.; Szakaly, Z.; Ohm, T.

1990-01-01

79

TAL effectors: tools for DNA targeting.  

PubMed

Xanthomonas phytopathogenic bacteria produce unique transcription activator-like effector (TALE) proteins that recognize and activate specific plant promoters through a set of tandem repeats. A unique TALE-DNA-binding code uses two polymorphic amino acids in each repeat to mediate recognition of specific nucleotides. The order of repeats determines effector's specificity toward the cognate nucleotide sequence of the sense DNA strand. Artificially designed TALE-DNA-binding domains fused to nuclease or activation and repressor domains provide an outstanding toolbox for targeted gene editing and gene regulation in research, biotechnology and gene therapy. Gene editing with custom-designed TALE nucleases (TALENs) extends the repertoire of targeted genome modifications across a broad spectrum of organisms ranging from plants and insect to mammals. PMID:24907364

Jankele, Radek; Svoboda, Petr

2014-09-01

80

Identification of Two Legionella pneumophila Effectors that Manipulate Host Phospholipids Biosynthesis  

PubMed Central

The intracellular pathogen Legionella pneumophila translocates a large number of effector proteins into host cells via the Icm/Dot type-IVB secretion system. Some of these effectors were shown to cause lethal effect on yeast growth. Here we characterized one such effector (LecE) and identified yeast suppressors that reduced its lethal effect. The LecE lethal effect was found to be suppressed by the over expression of the yeast protein Dgk1 a diacylglycerol (DAG) kinase enzyme and by a deletion of the gene encoding for Pah1 a phosphatidic acid (PA) phosphatase that counteracts the activity of Dgk1. Genetic analysis using yeast deletion mutants, strains expressing relevant yeast genes and point mutations constructed in the Dgk1 and Pah1 conserved domains indicated that LecE functions similarly to the Nem1-Spo7 phosphatase complex that activates Pah1 in yeast. In addition, by using relevant yeast genetic backgrounds we examined several L. pneumophila effectors expected to be involved in phospholipids biosynthesis and identified an effector (LpdA) that contains a phospholipase-D (PLD) domain which caused lethal effect only in a dgk1 deletion mutant of yeast. Additionally, LpdA was found to enhance the lethal effect of LecE in yeast cells, a phenomenon which was found to be dependent on its PLD activity. Furthermore, to determine whether LecE and LpdA affect the levels or distribution of DAG and PA in-vivo in mammalian cells, we utilized fluorescent DAG and PA biosensors and validated the notion that LecE and LpdA affect the in-vivo levels and distribution of DAG and PA, respectively. Finally, we examined the intracellular localization of both LecE and LpdA in human macrophages during L. pneumophila infection and found that both effectors are localized to the bacterial phagosome. Our results suggest that L. pneumophila utilize at least two effectors to manipulate important steps in phospholipids biosynthesis. PMID:23133385

Viner, Ram; Chetrit, David; Ehrlich, Marcelo; Segal, Gil

2012-01-01

81

Complement as effector system in cancer immunotherapy.  

PubMed

The contribution of the complement system to the control of tumour growth has been neglected for a long time as the major emphasis has been put mainly on cell-mediated immune response against cancer. With the introduction of monoclonal antibodies in cancer immunotherapy complement has come into play with a great potential as effector system. Complement has a number of advantages over other effector systems in that it is made of molecules that can easily penetrate the tumour tissue and a large majority, if not all, of the components of this system can be supplied locally by many cells at tissue site. Further advances are being made to increase the anti-tumour efficiency of the complements system using C-fixing antibodies that are modified in the Fc portion to be more active in complement activation. Another strategy currently investigated is essentially based on the use of a combination of two antibodies directed against different molecules or different epitopes of the same molecule expressed on the cell surface in order to increase the number of the binding sites for the antibodies on the tumor cells and the chance for them to activate complement more efficiently. One of the problems to solve in exploiting complement as an effector system in cancer immunotherapy is to neutralize the inhibitory effect of complement regulatory proteins which are often over-expressed on tumour cells and represent a mechanism of evasion of these cells from complement attack. This situation can be overcome using neutralizing antibodies to target onto tumour cells together with the specific antibodies directed against tumor specific antigens. This is an area of active investigation and the initial data that start to be available from animal models seem to be promising. PMID:17572509

Macor, Paolo; Tedesco, Francesco

2007-07-31

82

Common and contrasting themes in host cell-targeted effectors from bacterial, fungal, oomycete and nematode plant symbionts described using the Gene Ontology  

Microsoft Academic Search

A wide diversity of plant-associated symbionts, including microbes, produce proteins that can enter host cells, or are injected into host cells in order to modify the physiology of the host to promote colonization. These molecules, termed effectors, commonly target the host defense signaling pathways in order to suppress the defense response. Others target the gene expression machinery or trigger specific

Trudy Torto-Alalibo; Candace W Collmer; Magdalen Lindeberg; David Bird; Alan Collmer; Brett M Tyler

2009-01-01

83

Design and fabrication of an end effector  

NASA Technical Reports Server (NTRS)

The construction is described of a prototype mechanical hand or 'end effector' for use on a remotely controlled robot, but with possible application as a prosthetic device. An analysis of hand motions is reported, from which it is concluded that the two most important manipulations (apart from grasps) are to be able to pick up a tool and draw it into a nested grip against the palm, and to be able to hold a pistol-grip tool such as an electric drill and pull the trigger. A model was tested and found capable of both these operations.

Crossley, F. R. E.; Umholtz, F. G.

1975-01-01

84

Exploitation of Eukaryotic Subcellular Targeting Mechanisms by Bacterial Effectors  

PubMed Central

Several bacteria have evolved specialized secretion systems to deliver bacterial effector proteins into eukaryotic cells with the capacity to modulate cellular pathways to promote bacterial survival and replication. The spatial and temporal context in which effectors exert their biochemical activities is critical for their function. Understanding the mechanisms that lead to their precise subcellular localization following delivery into host cells is essential for understanding effector function in the context of infection. Recent studies have shown that bacterial effectors exploit host cellular machinery to accurately target their biochemical activities within the host cell. PMID:23588250

Hicks, Stuart W.; Galán, Jorge E.

2013-01-01

85

Rab35: GEFs, GAPs and effectors.  

PubMed

Rabs are the largest family of small GTPases and are master regulators of membrane trafficking. Following activation by guanine-nucleotide exchange factors (GEFs), each Rab binds a specific set of effector proteins that mediate the various downstream functions of that Rab. Then, with the help of GTPase-activating proteins, the Rab converts GTP to GDP, terminating its function. There are over 60 Rabs in humans and only a subset has been analyzed in any detail. Recently, Rab35 has emerged as a key regulator of cargo recycling at endosomes, with an additional role in regulation of the actin cytoskeleton. Here, we will focus on the regulation of Rab35 activity by the connecdenn/DENND1 family of GEFs and the TBC1D10/EPI64 family of GTPase-activating proteins. We will describe how analysis of these proteins, as well as a plethora of Rab35 effectors has provided insights into Rab35 function. Finally, we will describe how Rab35 provides a novel link between the Rab and Arf family of GTPases with implications for tumor formation and invasiveness. PMID:23905989

Chaineau, Mathilde; Ioannou, Maria S; McPherson, Peter S

2013-11-01

86

Immunomodulation by the Pseudomonas syringae HopZ Type III Effector Family in Arabidopsis  

PubMed Central

Pseudomonas syringae employs a type III secretion system to inject 20–30 different type III effector (T3SE) proteins into plant host cells. A major role of T3SEs is to suppress plant immune responses and promote bacterial infection. The YopJ/HopZ acetyltransferases are a superfamily of T3SEs found in both plant and animal pathogenic bacteria. In P. syringae, this superfamily includes the evolutionarily diverse HopZ1, HopZ2 and HopZ3 alleles. To investigate the roles of the HopZ family in immunomodulation, we generated dexamethasone-inducible T3SE transgenic lines of Arabidopsis for HopZ family members and characterized them for immune suppression phenotypes. We show that all of the HopZ family members can actively suppress various facets of Arabidopsis immunity in a catalytic residue-dependent manner. HopZ family members can differentially suppress the activation of mitogen-activated protein (MAP) kinase cascades or the production of reactive oxygen species, whereas all members can promote the growth of non-virulent P. syringae. Localization studies show that four of the HopZ family members containing predicted myristoylation sites are localized to the vicinity of the plasma membrane while HopZ3 which lacks the myristoylation site is at least partially nuclear localized, suggesting diversification of immunosuppressive mechanisms. Overall, we demonstrate that despite significant evolutionary diversification, all HopZ family members can suppress immunity in Arabidopsis. PMID:25546415

Lewis, Jennifer D.; Wilton, Mike; Mott, G . Adam; Lu, Wenwan; Hassan, Jana A.

2014-01-01

87

Common effector processing mediates cell-specific responses to stimuli  

E-print Network

LETTERS Common effector processing mediates cell-specific responses to stimuli Kathryn Miller components of many signalling pathways are common to all cells1­3 . However, stimulating or perturbing share a common `effector-processing' mechanism. Partial-least-squares regression models based on common

88

Mediation of the transition from biotrophy to necrotrophy in hemibiotrophic plant pathogens by secreted effector proteins.  

PubMed

Hemibiotrophs, such as Phytophthora infestans, exhibit distinct phases of their life cycle: an early asymptomatic biotrophic phase and a late necrotrophic stage that is characterized by tissue degradation and disease symptoms. To date, little is known of the molecular mechanisms that promote each distinct phase, nor those that mediate the transition between the two. We hypothesized that these phytopathogens might secrete distinct classes of effector proteins that first suppress plant defense responses and associated programmed cell death (PCD), and later induce large scale necrosis. To this end, we have identified proteins that are secreted by P. infestans early or late in the infection cycle. Recently we described the characterization of SNE1, which is specifically expressed during early biotrophic growth in the host plant tomato (Solanum lycopersicum). We found that SNE1 suppresses the action of necrosis-inducing effectors (Nep1-like proteins), including PiNPP1.1 and PsojNIP, which are secreted by Phytophthora during necrotrophic growth, as well as PCD mediated by a broad spectrum of Avr-R protein interactions. This suggests that SNE1 and PiNPP1.1 act antagonistically, thereby providing a highly regulated means to control the transition from biotrophy to necrotrophy. PMID:20400849

Lee, Sang-Jik; Rose, Jocelyn K C

2010-06-01

89

Rack Insertion End Effector (RIEE) automation  

NASA Technical Reports Server (NTRS)

NASA is developing a mechanism to manipulate and insert Racks into the Space Station Logistic modules. The mechanism consists of the following: a base with three motorized degrees of freedom, a 3 section motorized boom that goes from 15 to 44 feet in length, and a Rack Insertion End Effector (RIEE) with 5 hand wheels for precise alignment. The robotics section was tasked with the automation of the RIEE unit. In this report, for the automation of the RIEE unit, application of the Perceptics Vision System was conceptually developed to determine the position and orientation of the RIEE relative to the logistic module, and a MathCad program is written to display the needed displacements for precise alignment and final insertion of the Rack. The uniqueness of this report is that the whole report is in fact a MathCad program including text, derivations, and executable equations with example inputs and outputs.

Malladi, Narasimha

1993-01-01

90

Advanced Aerodynamic Design of Passive Porosity Control Effectors  

NASA Technical Reports Server (NTRS)

This paper describes aerodynamic design work aimed at developing a passive porosity control effector system for a generic tailless fighter aircraft. As part of this work, a computational design tool was developed and used to layout passive porosity effector systems for longitudinal and lateral-directional control at a low-speed, high angle of attack condition. Aerodynamic analysis was conducted using the NASA Langley computational fluid dynamics code USM3D, in conjunction with a newly formulated surface boundary condition for passive porosity. Results indicate that passive porosity effectors can provide maneuver control increments that equal and exceed those of conventional aerodynamic effectors for low-speed, high-alpha flight, with control levels that are a linear function of porous area. This work demonstrates the tremendous potential of passive porosity to yield simple control effector systems that have no external moving parts and will preserve an aircraft's fixed outer mold line.

Hunter, Craig A.; Viken, Sally A.; Wood, Richard M.; Bauer, Steven X. S.

2001-01-01

91

Double lead spiral platen parallel jaw end effector  

NASA Technical Reports Server (NTRS)

The double lead spiral platen parallel jaw end effector is an extremely powerful, compact, and highly controllable end effector that represents a significant improvement in gripping force and efficiency over the LaRC Puma (LP) end effector. The spiral end effector is very simple in its design and has relatively few parts. The jaw openings are highly predictable and linear, making it an ideal candidate for remote control. The finger speed is within acceptable working limits and can be modified to meet the user needs; for instance, greater finger speed could be obtained by increasing the pitch of the spiral. The force relaxation is comparable to the other tested units. Optimization of the end effector design would involve a compromise of force and speed for a given application.

Beals, David C.

1989-01-01

92

The Xanthomonas campestris effector protein XopDXcc8004 triggers plant disease tolerance by targeting DELLA proteins.  

PubMed

Plants protect themselves from the harmful effects of pathogens by resistance and tolerance. Disease resistance, which eliminates pathogens, can be modulated by bacterial type III effectors. Little is known about whether disease tolerance, which sustains host fitness with a given pathogen burden, is regulated by effectors. Here, we examined the effects of the Xanthomonas effector protein XopDXcc8004 on plant disease defenses by constructing knockout and complemented Xanthomonas strains, and performing inoculation studies in radish (Raphanus sativus L. var. radiculus XiaoJinZhong) and Arabidopsis plants. XopDXcc8004 suppresses disease symptoms without changing bacterial titers in infected leaves. In Arabidopsis, XopDXcc8004 delays the hormone gibberellin (GA)-mediated degradation of RGA (repressor of ga1-3), one of five DELLA proteins that repress GA signaling and promote plant tolerance under biotic and abiotic stresses. The ERF-associated amphiphilic repression (EAR) motif-containing region of XopDXcc8004 interacts with the DELLA domain of RGA and might interfere with the GA-induced binding of GID1, a GA receptor, to RGA. The EAR motif was found to be present in a number of plant transcriptional regulators. Thus, our data suggest that bacterial pathogens might have evolved effectors, which probably mimic host components, to initiate disease tolerance and enhance their survival. PMID:25040905

Tan, Leitao; Rong, Wei; Luo, Hongli; Chen, Yinhua; He, Chaozu

2014-11-01

93

System for exchanging tools and end effectors on a robot  

DOEpatents

A system and method for exchanging tools and end effectors on a robot permits exchange during a programmed task. The exchange mechanism is located off the robot, thus reducing the mass of the robot arm and permitting smaller robots to perform designated tasks. A simple spring/collet mechanism mounted on the robot is used which permits the engagement and disengagement of the tool or end effector without the need for a rotational orientation of the tool to the end effector/collet interface. As the tool changing system is not located on the robot arm no umbilical cords are located on robot.

Burry, David B. (Westminster, CO); Williams, Paul M. (Lafayette, CO)

1991-02-19

94

System for exchanging tools and end effectors on a robot  

DOEpatents

A system and method for exchanging tools and end effectors on a robot permits exchange during a programmed task. The exchange mechanism is located off the robot, thus reducing the mass of the robot arm and permitting smaller robots to perform designated tasks. A simple spring/collet mechanism mounted on the robot is used which permits the engagement and disengagement of the tool or end effector without the need for a rotational orientation of the tool to the end effector/collet interface. As the tool changing system is not located on the robot arm no umbilical cords are located on robot. 12 figures.

Burry, D.B.; Williams, P.M.

1991-02-19

95

Bacterial secreted effectors and caspase-3 interactions  

PubMed Central

Apoptosis is a critical process that intrinsically links organism survival to its ability to induce controlled death. Thus, functional apoptosis allows organisms to remove perceived threats to their survival by targeting those cells that it determines pose a direct risk. Central to this process are apoptotic caspases, enzymes that form a signalling cascade, converting danger signals via initiator caspases into activation of the executioner caspase, caspase-3. This enzyme begins disassembly of the cell by activating DNA degrading enzymes and degrading the cellular architecture. Interaction of pathogenic bacteria with caspases, and in particular, caspase-3, can therefore impact both host cell and bacterial survival. With roles outside cell death such as cell differentiation, control of signalling pathways and immunomodulation also being described for caspase-3, bacterial interactions with caspase-3 may be of far more significance in infection than previously recognized. In this review, we highlight the ways in which bacterial pathogens have evolved to subvert caspase-3 both through effector proteins that directly interact with the enzyme or by modulating pathways that influence its activation and activity. PMID:25262664

Wall, Daniel M; McCormick, Beth A

2014-01-01

96

Modes of TAL effector-mediated repression  

PubMed Central

Engineered transcription activator-like effectors, or TALEs, have emerged as a new class of designer DNA-binding proteins. Their DNA recognition sites can be specified with great flexibility. When fused to appropriate transcriptional regulatory domains, they can serve as designer transcription factors, modulating the activity of targeted promoters. We created tet operator (tetO)-specific TALEs (tetTALEs), with an identical DNA-binding site as the Tet repressor (TetR) and the TetR-based transcription factors that are extensively used in eukaryotic transcriptional control systems. Different constellations of tetTALEs and tetO modified chromosomal transcription units were analyzed for their efficacy in mammalian cells. We find that tetTALE-silencers can entirely abrogate expression from the strong human EF1? promoter when binding upstream of the transcriptional control sequence. Remarkably, the DNA-binding domain of tetTALE alone can effectively counteract trans-activation mediated by the potent tettrans-activator and also directly interfere with RNA polymerase II transcription initiation from the strong CMV promoter. Our results demonstrate that TALEs can act as highly versatile tools in genetic engineering, serving as trans-activators, trans-silencers and also competitive repressors. PMID:25389273

Werner, Jeannette; Gossen, Manfred

2014-01-01

97

SUMO as a nuclear hormone receptor effector  

PubMed Central

Animal development is driven by robust, cell-specific gene expression programs. Understanding mechanistically how a single transcription factor (TF) can govern distinct programs with exquisite precision is a major challenge. We view TFs as signal integrators, taking information from co-regulator interactions, post-translational modifications, other transcription factors, chromatin state, DNA sequence and in some cases, specific noncovalent ligands, to determine the collection of genes regulated by a TF at any given time. Here, we describe a reductionist approach to combinatorial transcriptional regulation, focusing on a single C. elegans TF, the nuclear hormone receptor NHR-25, and a single post-translational modification, SUMO. We suggest that the ratio of sumoylated to unsumoylated NHR-25 could specify a switch-like cell-fate decision during vulval development. Direct examination of this “SUMO ratio” in vivo is challenging and we discuss possible solutions going forward. We also consider how sumoylation of multiple substrates might be coordinated during vulval development. Finally, we note that iteration of this approach could leverage our sumoylation findings to define the roles of other effectors of NHR-25 in the developing vulva and in other tissues. PMID:25254154

Ward, Jordan D; Yamamoto, Keith R; Asahina, Masako

2014-01-01

98

Human Urinary Exosomes as Innate Immune Effectors  

PubMed Central

Exosomes are small extracellular vesicles, approximately 50 nm in diameter, derived from the endocytic pathway and released by a variety of cell types. Recent data indicate a spectrum of exosomal functions, including RNA transfer, antigen presentation, modulation of apoptosis, and shedding of obsolete protein. Exosomes derived from all nephron segments are also present in human urine, where their function is unknown. Although one report suggested in vitro uptake of exosomes by renal cortical collecting duct cells, most studies of human urinary exosomes have focused on biomarker discovery rather than exosome function. Here, we report results from in-depth proteomic analyses and EM showing that normal human urinary exosomes are significantly enriched for innate immune proteins that include antimicrobial proteins and peptides and bacterial and viral receptors. Urinary exosomes, but not the prevalent soluble urinary protein uromodulin (Tamm–Horsfall protein), potently inhibited growth of pathogenic and commensal Escherichia coli and induced bacterial lysis. Bacterial killing depended on exosome structural integrity and occurred optimally at the acidic pH typical of urine from omnivorous humans. Thus, exosomes are innate immune effectors that contribute to host defense within the urinary tract. PMID:24700864

Hiemstra, Thomas F.; Charles, Philip D.; Gracia, Tannia; Hester, Svenja S.; Gatto, Laurent; Al-Lamki, Rafia; Floto, R. Andres; Su, Ya; Skepper, Jeremy N.

2014-01-01

99

A Downy Mildew Effector Attenuates Salicylic Acid–Triggered Immunity in Arabidopsis by Interacting with the Host Mediator Complex  

PubMed Central

Plants are continually exposed to pathogen attack but usually remain healthy because they can activate defences upon perception of microbes. However, pathogens have evolved to overcome plant immunity by delivering effectors into the plant cell to attenuate defence, resulting in disease. Recent studies suggest that some effectors may manipulate host transcription, but the specific mechanisms by which such effectors promote susceptibility remain unclear. We study the oomycete downy mildew pathogen of Arabidopsis, Hyaloperonospora arabidopsidis (Hpa), and show here that the nuclear-localized effector HaRxL44 interacts with Mediator subunit 19a (MED19a), resulting in the degradation of MED19a in a proteasome-dependent manner. The Mediator complex of ?25 proteins is broadly conserved in eukaryotes and mediates the interaction between transcriptional regulators and RNA polymerase II. We found MED19a to be a positive regulator of immunity against Hpa. Expression profiling experiments reveal transcriptional changes resembling jasmonic acid/ethylene (JA/ET) signalling in the presence of HaRxL44, and also 3 d after infection with Hpa. Elevated JA/ET signalling is associated with a decrease in salicylic acid (SA)–triggered immunity (SATI) in Arabidopsis plants expressing HaRxL44 and in med19a loss-of-function mutants, whereas SATI is elevated in plants overexpressing MED19a. Using a PR1::GUS reporter, we discovered that Hpa suppresses PR1 expression specifically in cells containing haustoria, into which RxLR effectors are delivered, but not in nonhaustoriated adjacent cells, which show high PR1::GUS expression levels. Thus, HaRxL44 interferes with Mediator function by degrading MED19, shifting the balance of defence transcription from SA-responsive defence to JA/ET-signalling, and enhancing susceptibility to biotrophs by attenuating SA-dependent gene expression. PMID:24339748

Caillaud, Marie-Cécile; Asai, Shuta; Rallapalli, Ghanasyam; Piquerez, Sophie; Fabro, Georgina; Jones, Jonathan D. G.

2013-01-01

100

Robotic end-effector for rewaterproofing shuttle tiles  

NASA Astrophysics Data System (ADS)

This paper summarizes work by Rockwell International's Space Systems Division's Robotics Group at Downey, California. The work is part of a NASA-led team effort to automate Space Shuttle rewaterproofing in the Orbiter Processing Facility at the Kennedy Space Center and the ferry facility at the Ames-Dryden Flight Research Facility. Rockwell's effort focuses on the rewaterproofing end-effector, whose function is to inject hazardous dimethylethyloxysilane into thousands of ceramic tiles on the underside of the orbiter after each flight. The paper has five sections. First, it presents background on the present manual process. Second, end-effector requirements are presented, including safety and interface control. Third, a design is presented for the five end-effector systems: positioning, delivery, containment, data management, and command and control. Fourth, end-effector testing and integrating to the total system are described. Lastly, future applications for this technology are discussed.

Manouchehri, Davoud; Hansen, Joseph M.; Wu, Cheng M.; Yamamoto, Brian S.; Graham, Todd

1992-11-01

101

Design, testing and evaluation of latching end effector  

NASA Technical Reports Server (NTRS)

The Latching End Effector (LEE) forms part of the Space Station Remote Manipulator System (SSRMS) for which Spar Aerospace Ltd, Space Systems Division is the prime contractor. The design, testing and performance evaluation of the Latching End Effector mechanisms is the subject of this paper focusing on: (1) ambient, thermal and vibration testing; (2) snare/rigidize performance testing and interaction during payload acquisition; and (3) latch/umbilical test results and performance.

Walker, B.; Vandersluis, R.

1995-01-01

102

Multiple Activities of the Plant Pathogen Type III Effector Proteins WtsE and AvrE1 require WxxxE Motifs  

PubMed Central

The broadly conserved AvrE-family of type III effectors from Gram-negative plant pathogenic bacteria includes important virulence factors, yet little is known about the mechanisms by which these effectors function inside plant cells to promote disease. We have identified two conserved motifs in AvrE-family effectors: a WxxxE motif and a putative C-terminal endoplasmic reticulum membrane retention/retrieval signal (ERMRS). The WxxxE and ERMRS motifs are both required for the virulence activities of WtsE and AvrE1, which are major virulence factors of the corn pathogen Pantoea stewartii subsp. stewartii and the tomato/Arabidopsis pathogen Pseudomonas syringae pv. tomato, respectively. The WxxxE and the predicted ERMRS motifs are also required for other biological activities of WtsE, including elicitation of the hypersensitive response in nonhost plants and suppression of defense responses in Arabidopsis. A family of type III effectors from mammalian bacterial pathogens requires WxxxE and sub-cellular targeting motifs for virulence functions that involve their ability to mimic activated G-proteins. The conservation of related motifs and their necessity for the function of type III effectors from plant pathogens indicates that disturbing host pathways by mimicking activated host G-proteins may be a virulence mechanism employed by plant pathogens as well. PMID:19445595

Ham, Jong Hyun; Majerczak, Doris R.; Nomura, Kinya; Mecey, Christy; Uribe, Francisco; He, Sheng-Yang; Mackey, David; Coplin, David L.

2009-01-01

103

ATP as effector of inorganic pyrophosphatase of Escherichia coli . The role of residue Lys112 in binding effectors  

Microsoft Academic Search

It has been shown that PPi, methylenediphosphonate, and ATP act as effectors of Escherichia coli inorganic pyrophosphatase (E-PPase), and that they compete for binding at the allosteric regulatory site. On the basis of\\u000a chemical modification and computer modeling of a structure of the enzyme-ATP complex, a number of amino acid residues presumably\\u000a involved in binding effectors has been revealed. Mutant

E. V. Rodina; N. N. Vorobyeva; S. A. Kurilova; T. S. Sitnik; T. I. Nazarova

2007-01-01

104

Nonspecific hemolytic effector of activated macrophages as activation marker of allograft rejection.  

PubMed

The aim was to assess a nonspecific hemolytic effector of activated monocytes/macrophages, designated spontaneous plaque-forming cell (SPFC), as an activation marker in allograft rejection. An in vitro study on the immunologic characteristics of SPFC monocytes in man and an in vivo study in Lewis rats as to the monitoring of SPFC generation of allograft infiltrating cells with or without immunosuppression were conducted. Hemolysis of SPFC was mediated by CR3 adhesion molecules, detected by Mo-1 and OKM10 monoclonal antibodies. Hemolysis of SPFC was nonspecific, and nonrosette-forming T cells with autologous erythrocytes (non-ARFC-T) acted as suppressor T cells inhibiting SPFC-hemolysis against autologous erythrocytes. A 6-day course of immunosuppression with a daily dose of cyclosporin A (CyA) 10 mg/kg and of FK506 1 mg/kg suppressed the SPFC generation to the level of syngeneic control. In contrast, peak SPFC generation coincided with rejection, and the degree of SPFC generation reflected the grade of histoincompatibility. The present findings suggested that SPFC-activated monocytes/macrophages may be one of the activation markers in allograft rejection and lead to a new concept of graft rejection and self or nonself discrimination mediated by nonspecific, hemolytic SPFC effectors and suppressor T cells inhibiting autoreactivity. PMID:14621804

Ishibashi, M; Moutabarrik, A; Kameoka, H; Takano, Y; Jiang, H; Kokado, Y; Takahara, S

1992-01-01

105

A Translocated Effector Required for Bartonella Dissemination from Derma to Blood Safeguards Migratory Host Cells from Damage by Co-translocated Effectors  

E-print Network

Numerous bacterial pathogens secrete multiple effectors to modulate host cellular functions. These effectors may interfere with each other to efficiently control the infection process. Bartonellae are Gram-negative, ...

Okujava, Rusudan

106

Innate Immunity in Plants: An Arms Race Between Pattern Recognition Receptors in Plants and Effectors in Microbial Pathogens  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Plant defense responses known as PAMP-triggered immunity (PTI) begin when the plant is exposed to microbial elicitors named pathogen- or microbe-associated molecular patterns (PAMPs or MAMPs). Recent studies provide an elegant explanation for the difficulty of demonstrating the role of PTI in plant disease resistance. It turns out that the important contribution of PTI to disease resistance is masked by pathogen virulence effectors that have evolved to suppress it.

Thomas Boller (University of Basel;Zurich-Basel Plant Science Center, Botanical Institute); Sheng Yang He (Michigan State University;Department of Energy Plant Research Laboratory, Department of Plant Biology)

2009-05-08

107

Stem Cell Reports Suppression of the SOX2 Neural Effector Gene by PRDM1 Promotes Human  

E-print Network

repressor Prdm1/Blimp-1 is known to play a critical role in controlling germ cell specification in mice repressor PRDM1, also known as B lymphocyte-induced maturation protein-1 (Blimp-1), was identified

Yeang, Chen-Hsiang

108

IL-17 suppresses immune effector functions in human papillomavirus-associated epithelial hyperplasia.  

PubMed

Persistent infection with high-risk human papillomaviruses (HPV) causes epithelial hyperplasia that can progress to cancer and is thought to depend on immunosuppressive mechanisms that prevent viral clearance by the host. IL-17 is a cytokine with diverse functions in host defense and in the pathology of autoimmune disorders, chronic inflammatory diseases, and cancer. We analyzed biopsies from patients with HPV-associated cervical intraepithelial neoplasia grade 2/3 and murine skin displaying HPV16 E7 protein-induced epithelial hyperplasia, which closely models hyperplasia in chronic HPV lesions. Expression of IL-17 and IL-23, a major inducer of IL-17, was elevated in both human HPV-infected and murine E7-expressing lesions. Using a skin-grafting model, we demonstrated that IL-17 in HPV16 E7 transgenic skin grafts inhibited effective host immune responses against the graft. IL-17 was produced by CD3(+) T cells, predominantly CD4(+) T cells in human, and CD4(+) and ?? T cells in mouse hyperplastic lesions. IL-23 and IL-1?, but not IL-18, induced IL-17 production in E7 transgenic skin. Together, these findings demonstrate an immunosuppressive role for IL-17 in HPV-associated epithelial hyperplasia and suggest that blocking IL-17 in persistent viral infection may promote antiviral immunity and prevent progression to cancer. PMID:25063870

Gosmann, Christina; Mattarollo, Stephen R; Bridge, Jennifer A; Frazer, Ian H; Blumenthal, Antje

2014-09-01

109

Ras effector mutant expression suggest a negative regulator inhibits lung tumor formation.  

PubMed

Lung cancer is currently the most deadly malignancy in industrialized countries and accounts for 18% of all cancer-related deaths worldwide. Over 70% of patients with non-small cell lung cancer (NSCLC) are diagnosed at a late stage, with a 5-year survival below 10%. KRAS and the EGFR are frequently mutated in NSCLC and while targeted therapies for patients with EGFR mutations exist, oncogenic KRAS is thus far not druggable. KRAS activates multiple signalling pathways, including the PI3K/Akt pathway, the Raf-Mek-Erk pathway and the RalGDS/Ral pathway. Lung-specific expression of BrafV600E, the most prevalent BRAF mutation found in human tumors, results in Raf-Mek-Erk pathway activation and in the formation of benign adenomas that undergo widespread senescence in a Cre-activated Braf mouse model (Braf(CA)). However, oncogenic KRAS expression in mice induces adenocarcinomas, suggesting additional KRAS-activated pathways cooperate with sustained RAF-MEK-ERK signalling to bypass the oncogene-induced senescence proliferation arrest. To determine which KRAS effectors were responsible for tumor progression, we created four effector domain mutants (S35, G37, E38 and C40) in G12V-activated KRAS and expressed these alone or with BrafV600E in mouse lungs... The S35 and E38 mutants bind to Raf proteins but not PI3K or RalGDS; the G37 mutant binds to RalGDS and not Raf or PI3K and the C40 mutant is specific to PI3K. We designed lentiviral vectors to code for Cre recombinase along with KRAS mutants (V12, V12/S35, V12/G37, V12/E38 or V12/C40) or EGFP as a negative control.. These lentiviruses were used to infect Braf(CA) and wild-type mice. Surprisingly there was a significant decrease in tumor number and penetrance with each KRAS effector domain mutant relative to controls, suggesting that KRAS directly activates effectors with tumor suppressive functions. PMID:24489653

Vandal, Guillaume; Geiling, Benjamin; Dankort, David

2014-01-01

110

Ras Effector Mutant Expression Suggest a Negative Regulator Inhibits Lung Tumor Formation  

PubMed Central

Lung cancer is currently the most deadly malignancy in industrialized countries and accounts for 18% of all cancer-related deaths worldwide. Over 70% of patients with non-small cell lung cancer (NSCLC) are diagnosed at a late stage, with a 5-year survival below 10%. KRAS and the EGFR are frequently mutated in NSCLC and while targeted therapies for patients with EGFR mutations exist, oncogenic KRAS is thus far not druggable. KRAS activates multiple signalling pathways, including the PI3K/Akt pathway, the Raf-Mek-Erk pathway and the RalGDS/Ral pathway. Lung-specific expression of BrafV600E, the most prevalent BRAF mutation found in human tumors, results in Raf-Mek-Erk pathway activation and in the formation of benign adenomas that undergo widespread senescence in a Cre-activated Braf mouse model (BrafCA). However, oncogenic KRAS expression in mice induces adenocarcinomas, suggesting additional KRAS-activated pathways cooperate with sustained RAF-MEK-ERK signalling to bypass the oncogene-induced senescence proliferation arrest. To determine which KRAS effectors were responsible for tumor progression, we created four effector domain mutants (S35, G37, E38 and C40) in G12V-activated KRAS and expressed these alone or with BrafV600E in mouse lungs… The S35 and E38 mutants bind to Raf proteins but not PI3K or RalGDS; the G37 mutant binds to RalGDS and not Raf or PI3K and the C40 mutant is specific to PI3K. We designed lentiviral vectors to code for Cre recombinase along with KRAS mutants (V12, V12/S35, V12/G37, V12/E38 or V12/C40) or EGFP as a negative control.. These lentiviruses were used to infect BrafCA and wild-type mice. Surprisingly there was a significant decrease in tumor number and penetrance with each KRAS effector domain mutant relative to controls, suggesting that KRAS directly activates effectors with tumor suppressive functions. PMID:24489653

Vandal, Guillaume; Geiling, Benjamin; Dankort, David

2014-01-01

111

The effector T cell response to influenza infection.  

PubMed

Influenza virus infection induces a potent initial innate immune response, which serves to limit the extent of viral replication and virus spread. However, efficient (and eventual) viral clearance within the respiratory tract requires the subsequent activation, rapid proliferation, recruitment, and expression of effector activities by the adaptive immune system, consisting of antibody producing B cells and influenza-specific T lymphocytes with diverse functions. The ensuing effector activities of these T lymphocytes ultimately determine (along with antibodies) the capacity of the host to eliminate the viruses and the extent of tissue damage. In this review, we describe this effector T cell response to influenza virus infection. Based on information largely obtained in experimental settings (i.e., murine models), we will illustrate the factors regulating the induction of adaptive immune T cell responses to influenza, the effector activities displayed by these activated T cells, the mechanisms underlying the expression of these effector mechanisms, and the control of the activation/differentiation of these T cells, in situ, in the infected lungs. PMID:25033753

Hufford, Matthew M; Kim, Taeg S; Sun, Jie; Braciale, Thomas J

2015-01-01

112

Potency of Transgenic Effectors for Neurogenetic Manipulation in Drosophila Larvae.  

PubMed

Genetic manipulations of neuronal activity are a corner stone of studies aimed to identify the functional impact of defined neurons for animal behavior. With its small nervous system, rapid life cycle and genetic amenability, the fruit fly Drosophila melanogaster provides an attractive model system to study neuronal circuit function. In the past two decades, a large repertoire of elegant genetic tools has been developed to manipulate and study neural circuits in the fruit fly. Current techniques allow genetic ablation, constitutive silencing or hyperactivation of neuronal activity, and also include conditional thermogenetic or optogenetic activation or inhibition. As for all genetic techniques, the choice of the proper transgenic tool is essential for behavioral studies. Potency and impact of effectors may vary in distinct neuron types or distinct types of behavior. We here systematically test genetic effectors for their potency to alter the behavior of Drosophila larvae using two distinct behavioral paradigms: general locomotor activity and directed, visually guided navigation. Our results show largely similar but not equal effects with different effector lines in both assays. Interestingly, differences in the magnitude of induced behavioral alterations between different effector lines remain largely consistent between the two behavioral assays. The observed potencies of the effector lines in aminergic and cholinergic neurons assessed here may help to choose the best-suited genetic tools to dissect neuronal networks underlying the behavior of larval fruit flies. PMID:25359929

Pauls, Dennis; von Essen, Alina; Lyutova, Radostina; van Giesen, Lena; Rosner, Ronny; Wegener, Christian; Sprecher, Simon G

2014-10-29

113

Lineage relationship of effector and memory T cells  

PubMed Central

Adaptive immunity is characterized by the ability to form long-lived immunological memory. Upon re-exposure to antigen, memory T cells respond more rapidly and robustly than naïve T cells, providing better clearance of pathogens. Recent reviews have reinforced the text-book view that memory T cells arise from effector cells. Although this notion is teleologically appealing, emerging data is more consistent with a model where naïve cells directly develop into memory cells without transitioning through an effector stage. A clear understanding of the lineage relationships between memory and effector cells has profound implications for the design of vaccines and for the development of effective T cell-based therapies. PMID:24148236

Restifo, Nicholas P.; Gattinoni, Luca

2013-01-01

114

Ralstonia solanacearum Requires PopS, an Ancient AvrE-Family Effector, for Virulence and To Overcome Salicylic Acid-Mediated Defenses during Tomato Pathogenesis  

PubMed Central

ABSTRACT During bacterial wilt of tomato, the plant pathogen Ralstonia solanacearum upregulates expression of popS, which encodes a type III-secreted effector in the AvrE family. PopS is a core effector present in all sequenced strains in the R. solanacearum species complex. The phylogeny of popS mirrors that of the species complex as a whole, suggesting that this is an ancient, vertically inherited effector needed for association with plants. A popS mutant of R. solanacearum UW551 had reduced virulence on agriculturally important Solanum spp., including potato and tomato plants. However, the popS mutant had wild-type virulence on a weed host, Solanum dulcamara, suggesting that some species can avoid the effects of PopS. The popS mutant was also significantly delayed in colonization of tomato stems compared to the wild type. Some AvrE-type effectors from gammaproteobacteria suppress salicylic acid (SA)-mediated plant defenses, suggesting that PopS, a betaproteobacterial ortholog, has a similar function. Indeed, the popS mutant induced significantly higher expression of tomato SA-triggered pathogenesis-related (PR) genes than the wild type. Further, pretreatment of roots with SA exacerbated the popS mutant virulence defect. Finally, the popS mutant had no colonization defect on SA-deficient NahG transgenic tomato plants. Together, these results indicate that this conserved effector suppresses SA-mediated defenses in tomato roots and stems, which are R. solanacearum’s natural infection sites. Interestingly, PopS did not trigger necrosis when heterologously expressed in Nicotiana leaf tissue, unlike the AvrE homolog DspEPcc from the necrotroph Pectobacterium carotovorum subsp. carotovorum. This is consistent with the differing pathogenesis modes of necrosis-causing gammaproteobacteria and biotrophic R. solanacearum. PMID:24281716

Jacobs, Jonathan M.; Milling, Annett; Mitra, Raka M.; Hogan, Clifford S.; Ailloud, Florent; Prior, Philippe; Allen, Caitilyn

2013-01-01

115

Pseudomonas syringae Hrp type III secretion system and effector proteins  

PubMed Central

Pseudomonas syringae is a member of an important group of Gram-negative bacterial pathogens of plants and animals that depend on a type III secretion system to inject virulence effector proteins into host cells. In P. syringae, hrp/hrc genes encode the Hrp (type III secretion) system, and avirulence (avr) and Hrp-dependent outer protein (hop) genes encode effector proteins. The hrp/hrc genes of P. syringae pv syringae 61, P. syringae pv syringae B728a, and P. syringae pv tomato DC3000 are flanked by an exchangeable effector locus and a conserved effector locus in a tripartite mosaic Hrp pathogenicity island (Pai) that is linked to a tRNALeu gene found also in Pseudomonas aeruginosa but without linkage to Hrp system genes. Cosmid pHIR11 carries a portion of the strain 61 Hrp pathogenicity island that is sufficient to direct Escherichia coli and Pseudomonas fluorescens to inject HopPsyA into tobacco cells, thereby eliciting a hypersensitive response normally triggered only by plant pathogens. Large deletions in strain DC3000 revealed that the conserved effector locus is essential for pathogenicity but the exchangeable effector locus has only a minor role in growth in tomato. P. syringae secretes HopPsyA and AvrPto in culture in a Hrp-dependent manner at pH and temperature conditions associated with pathogenesis. AvrPto is also secreted by Yersinia enterocolitica. The secretion of AvrPto depends on the first 15 codons, which are also sufficient to direct the secretion of an Npt reporter from Y. enterocolitica, indicating that a universal targeting signal is recognized by the type III secretion systems of both plant and animal pathogens. PMID:10922033

Collmer, Alan; Badel, Jorge L.; Charkowski, Amy O.; Deng, Wen-Ling; Fouts, Derrick E.; Ramos, Adela R.; Rehm, Amos H.; Anderson, Deborah M.; Schneewind, Olaf; van Dijk, Karin; Alfano, James R.

2000-01-01

116

How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells?  

PubMed Central

Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens. PMID:24586116

Petre, Benjamin; Kamoun, Sophien

2014-01-01

117

Robotic End Effectors for Hard-Rock Climbing  

NASA Technical Reports Server (NTRS)

Special-purpose robot hands (end effectors) now under development are intended to enable robots to traverse cliffs much as human climbers do. Potential applications for robots having this capability include scientific exploration (both on Earth and other rocky bodies in space), military reconnaissance, and outdoor search and rescue operations. Until now, enabling robots to traverse cliffs has been considered too difficult a task because of the perceived need of prohibitively sophisticated planning algorithms as well as end effectors as dexterous as human hands. The present end effectors are being designed to enable robots to attach themselves to typical rock-face features with less planning and simpler end effectors. This advance is based on the emulation of the equipment used by human climbers rather than the emulation of the human hand. Climbing-aid equipment, specifically cams, aid hooks, and cam hooks, are used by sport climbers when a quick ascent of a cliff is desired (see Figure 1). Currently two different end-effector designs have been created. The first, denoted the simple hook emulator, consists of three "fingers" arranged around a central "palm." Each finger emulates the function of a particular type of climbing hook (aid hook, wide cam hook, and a narrow cam hook). These fingers are connected to the palm via a mechanical linkage actuated with a leadscrew/nut. This mechanism allows the fingers to be extended or retracted. The second design, denoted the advanced hook emulator (see Figure 2), shares these features, but it incorporates an aid hook and a cam hook into each finger. The spring-loading of the aid hook allows the passive selection of the type of hook used. The end effectors can be used in several different modes. In the aid-hook mode, the aid hook on one of the fingers locks onto a horizontal ledge while the other two fingers act to stabilize the end effector against the cliff face. In the cam-hook mode, the broad, flat tip of the cam hook is inserted into a non-horizontal crack in the cliff face. A subsequent transfer of weight onto the end effector causes the tip to rotate within the crack, creating a passive, self-locking action of the hook relative to the crack. In the advanced hook emulator, the aid hook is pushed into its retracted position by contact with the cliff face as the cam hook tip is inserted into the crack. When a cliff face contains relatively large pockets or cracks, another type of passive self-locking can be used. Emulating the function of the piece of climbing equipment called a "cam" (note: not the same as a "cam hook"; see Figure 1), the fingers can be fully retracted and the entire end effector inserted into the feature. The fingers are then extended as far as the feature allows. Any weight then transferred to the end effector will tend to extend the fingers further due to frictional force, passively increasing the grip on the feature. In addition to the climbing modes, these end effectors can be used to walk on (either on the palm or the fingertips) and to grasp objects by fully extending the fingers.

Kennedy, Brett; Leger, Patrick

2004-01-01

118

Expression of enteropathogenic Escherichia coli map is significantly different than that of other type III secreted effectors in vivo.  

PubMed

The enteropathogenic Escherichia coli (EPEC) locus of enterocyte effacement (LEE)-encoded effectors EspF and Map are multifunctional and have an impact on the tight junction barrier while the non-LEE-encoded proteins NleH1 and NleH2 possess significant anti-inflammatory activity. In order to address the temporal expression of these important genes in vivo, their promoters were cloned upstream of the luxCDABE operon, and luciferase expression was measured in EPEC-infected mice by bioluminescence using an in vivo imaging system (IVIS). Bioluminescent images of living mice, of excised whole intestines, and of whole intestines longitudinally opened and washed were assessed. The majority of bioluminescent bacteria localized in the cecum by 3 h postinfection, indicating that the cecum is not only a major colonization site of EPEC but also a site of EPEC effector gene expression in mice. espF, nleH1, and nleH2 were abundantly expressed over the course of infection. In contrast, map expression was suppressed at 2 days postinfection, and at 4 days postinfection it was totally abolished. After 2 to 4 days postinfection, when map is suppressed, EPEC colonization is significantly reduced, indicating that map may be one of the factors required to maintain EPEC colonization. This was confirmed in a competitive colonization study and in two models of chronic infection, repeated exposure to ketamine and Citrobacter rodentium infection. Our data suggest that map expression contributes to the maintenance of EPEC colonization. PMID:25312947

Nguyen, Mai; Rizvi, Jason; Hecht, Gail

2015-01-01

119

Cell Host & Microbe Bacterial Effectors Target the Common Signaling  

E-print Network

Cell Host & Microbe Article Bacterial Effectors Target the Common Signaling Partner BAK1 to Disrupt and Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA 6These convergent innate immune responses stimulated by multiple microbe-associ- ated molecular patterns (MAMPs

Pawlowski, Wojtek

120

Distinct regulation of effector and memory T-cell differentiation  

E-print Network

-bet, Eomes and Blimp-1, all of which are crucial in the differentiation and homoeostasis of effector: transcription factors; Blimp-1; Bcl-6; T-bet; IL2; IL12 During an immune response, nai¨ve T cells respond

Cai, Long

121

Ehrlichia Moonlighting Effectors and Interkingdom Interactions with the Mononuclear Phagocyte  

PubMed Central

Ehrlichia chaffeensis is an obligately intracellular gram negative bacterium with a small genome that thrives in mammalian mononuclear phagoctyes by exploiting eukaryotic processes. Herein, we discuss the latest findings on moonlighting tandem repeat protein effectors and their secretion mechanisms, and novel molecular interkingdom interactions that provide insight into the intracellular pathobiology of ehrlichiae. PMID:24141087

Dunphy, Paige Selvy; Luo, Tian; McBride, Jere W.

2013-01-01

122

The Coding and Effector Transfer of Movement Sequences  

ERIC Educational Resources Information Center

Three experiments utilizing a 14-element arm movement sequence were designed to determine if reinstating the visual-spatial coordinates, which require movements to the same spatial locations utilized during acquisition, results in better effector transfer than reinstating the motor coordinates, which require the same pattern of homologous muscle…

Kovacs, Attila J.; Muhlbauer, Thomas; Shea, Charles H.

2009-01-01

123

Protein kinase C and other diacylglycerol effectors in cancer  

Microsoft Academic Search

Almost three decades after the discovery of protein kinase C (PKC), we still have only a partial understanding of how this family of serine\\/threonine kinases is involved in tumour promotion. PKC isozymes — effectors of diacylglycerol (DAG) and the main targets of phorbol-ester tumour promoters — have important roles in cell-cycle regulation, cellular survival, malignant transformation and apoptosis. How do

Erin M. Griner; Marcelo G. Kazanietz

2007-01-01

124

Toward a Comprehensive Map of the Effectors of Rab GTPases  

PubMed Central

Summary The Rab GTPases recruit peripheral membrane proteins to intracellular organelles. These Rab effectors typically mediate the motility of organelles and vesicles and contribute to the specificity of membrane traffic. However, for many Rabs, few, if any, effectors have been identified; hence, their role remains unclear. To identify Rab effectors, we used a comprehensive set of Drosophila Rabs for affinity chromatography followed by mass spectrometry to identify the proteins bound to each Rab. For many Rabs, this revealed specific interactions with Drosophila orthologs of known effectors. In addition, we found numerous Rab-specific interactions with known components of membrane traffic as well as with diverse proteins not previously linked to organelles or having no known function. We confirm over 25 interactions for Rab2, Rab4, Rab5, Rab6, Rab7, Rab9, Rab18, Rab19, Rab30, and Rab39. These include tethering complexes, coiled-coiled proteins, motor linkers, Rab regulators, and several proteins linked to human disease. PMID:25453831

Gillingham, Alison K.; Sinka, Rita; Torres, Isabel L.; Lilley, Kathryn S.; Munro, Sean

2014-01-01

125

Hand to Mouth: Automatic Imitation across Effector Systems  

ERIC Educational Resources Information Center

The effector dependence of automatic imitation was investigated using a stimulus-response compatibility (SRC) procedure during which participants were required to make an open or closed response with their hand or their mouth. The correct response for each trial was indicated by a pair of letters in Experiments 1 and 2 and by a colored square in…

Leighton, Jane; Heyes, Cecilia

2010-01-01

126

Competition for IL-2 between Regulatory and Effector T Cells to Chisel Immune Responses  

PubMed Central

In this review we discuss how the competition for cytokines between different cells of the immune system can shape the system wide immune response. We focus on interleukin-2 (IL-2) secretion by activated effector T cells (Teff) and on the competition for IL-2 consumption between Teff and regulatory T cells (Treg). We discuss the evidence for the mechanism in which the depletion of IL-2 by Treg cells would be sufficient to suppress an autoimmune response, yet not strong enough to prevent an immune response. We present quantitative estimations and summarize our modeling effort to show that the tug-of-war between Treg and Teff cells for IL-2 molecules can be won by Treg cells in the case of weak activation of Teff leading to the suppression of the immune response. Or, for strongly activated Teff cells, it can be won by Teff cells bringing about the activation of the whole adaptive immune system. Finally, we discuss some recent applications attempting to achieve clinical effects through the modulation of IL-2 consumption by Treg compartment. PMID:22973270

Höfer, Thomas; Krichevsky, Oleg; Altan-Bonnet, Grégoire

2012-01-01

127

Opening the Ralstonia solanacearum type III effector tool box: insights into host cell subversion mechanisms.  

PubMed

Effectors delivered to host cells by the Type III secretion system are essential to Ralstonia solanacearum pathogenicity, as in several other plant pathogenic bacteria. The establishment of exhaustive effector repertoires in multiple R. solanacearum strains drew a first picture of the evolutionary dynamics of the pathogen effector suites. Effector repertoires are diversified, with a core of 20-30 effectors present in most of the strains and the obtention of mutants lacking one or more effector genes revealed the functional overlap among this effector network. Recent functional studies have provided insights into the ability of single effectors to manipulate the host proteasome, elicit cell death, trigger the expression of plant genes, and/or display biochemical activities on plant protein targets. PMID:24880553

Deslandes, Laurent; Genin, Stephane

2014-08-01

128

Kinetics and activation requirements of contact-dependent immune suppression by human regulatory T cells.  

PubMed

Naturally occurring regulatory T cells (Tregs) maintain self tolerance by dominant suppression of potentially self-reactive T cells in peripheral tissues. However, the activation requirements, the temporal aspects of the suppressive activity, and mode of action of human Tregs are subjects of controversy. In this study, we show that Tregs display significant variability in the suppressive activity ex vivo as 54% of healthy blood donors examined had fully suppressive Tregs spontaneously, whereas in the remaining donors, anti-CD3/CD2/CD28 stimulation was required for Treg suppressive activity. Furthermore, anti-CD3/CD2/CD28 stimulation for 6 h and subsequent fixation in paraformaldehyde rendered the Tregs fully suppressive in all donors. The fixation-resistant suppressive activity of Tregs operated in a contact-dependent manner that was not dependent on APCs, but could be fully obliterated by trypsin treatment, indicating that a cell surface protein is directly involved. By add-back of active, fixed Tregs at different time points after activation of responding T cells, the responder cells were susceptible to Treg-mediated immune suppression up to 24 h after stimulation. This defines a time window in which effector T cells are susceptible to Treg-mediated immune suppression. Lastly, we examined the effect of a set of signaling inhibitors that perturb effector T cell activation and found that none of the examined inhibitors affected Treg activation, indicating pathway redundancy or that Treg activation proceeds by signaling mechanisms distinct from those of effector T cells. PMID:22539784

Hagness, Morten; Henjum, Karen; Landskron, Johannes; Brudvik, Kristoffer Watten; Bjørnbeth, Bjørn Atle; Foss, Aksel; Taskén, Kjetil; Aandahl, Einar Martin

2012-06-01

129

The Shigella flexneri OspB effector: an early immunomodulator.  

PubMed

Through the action of the type three secretion system (T3SS) Shigella flexneri delivers several effectors into host cells to promote cellular invasion, multiplication and to exploit host-cell signaling pathways to modulate the host innate immune response. Although much progress has been made in the understanding of many type III effectors, the molecular and cellular mechanism of the OspB effector is still poorly characterized. In this study we present new evidence that better elucidates the role of OspB as pro-inflammatory factor at very early stages of infection. Indeed, we demonstrate that, during the first hour of infection, OspB is required for full activation of ERK1/2 and p38 MAPKs and the cytosolic phospholipase A2 (cPLA2). Activation of cPLA2 ultimately leads to the production and secretion of PMN chemoattractant metabolite(s) uncoupled with release of IL-8. Moreover, we also present evidence that OspB is required for the development of the full and promptly inflammatory reaction characteristic of S. flexneri wild-type infection in vivo. Based on OspB and OspF similarity (both effectors share similar transcription regulation, temporal secretion into host cells and nuclear localization) we hypothesized that OspB and OspF effectors may form a pair aimed at modulating the host cell response throughout the infection process, with opposite effects. A model is presented to illustrate how OspB activity would promote S. flexneri invasion and bacterial dissemination at early critical phases of infection. PMID:25434600

Ambrosi, Cecilia; Pompili, Monica; Scribano, Daniela; Limongi, Dolores; Petrucca, Andrea; Cannavacciuolo, Sonia; Schippa, Serena; Zagaglia, Carlo; Grossi, Milena; Nicoletti, Mauro

2015-01-01

130

Active Flow Effectors for Noise and Separation Control  

NASA Technical Reports Server (NTRS)

New flow effector technology for separation control and enhanced mixing is based upon shape memory alloy hybrid composite (SMAHC) technology. The technology allows for variable shape control of aircraft structures through actively deformable surfaces. The flow effectors are made by embedding shape memory alloy actuator material in a composite structure. When thermally actuated, the flow effector def1ects into or out of the flow in a prescribed manner to enhance mixing or induce separation for a variety of applications, including aeroacoustic noise reduction, drag reduction, and f1ight control. The active flow effectors were developed for noise reduction as an alternative to fixed-configuration effectors, such as static chevrons, that cannot be optimized for airframe installation effects or variable operating conditions and cannot be retracted for off-design or fail-safe conditions. Benefits include: Increased vehicle control, overall efficiency, and reduced noise throughout all f1ight regimes, Reduced flow noise, Reduced drag, Simplicity of design and fabrication, Simplicity of control through direct current stimulation, autonomous re sponse to environmental heating, fast re sponse, and a high degree of geometric stability. The concept involves embedding prestrained SMA actuators on one side of the chevron neutral axis in order to generate a thermal moment and def1ect the structure out of plane when heated. The force developed in the host structure during def1ection and the aerodynamic load is used for returning the structure to the retracted position. The chevron design is highly scalable and versatile, and easily affords active and/or autonomous (environmental) control. The technology offers wide-ranging market applications, including aerospace, automotive, and any application that requires flow separation or noise control.

Turner, Travis L.

2011-01-01

131

ATP as effector of inorganic pyrophosphatase of Escherichia coli. The role of residue Lys112 in binding effectors.  

PubMed

It has been shown that PP(i), methylenediphosphonate, and ATP act as effectors of Escherichia coli inorganic pyrophosphatase (E-PPase), and that they compete for binding at the allosteric regulatory site. On the basis of chemical modification and computer modeling of a structure of the enzyme-ATP complex, a number of amino acid residues presumably involved in binding effectors has been revealed. Mutant variants Lys112Gln, Lys112Gln/Lys148Gln, and Lys112Gln/Lys115Ala of E-PPase have been obtained, as well as a modified variant of wild type E-PPase ((Ad)wt PPase) with a derivative of ATP chemically attached to the amino group of Lys146. Kinetic properties of these variants have been investigated and compared to the earlier described variants Lys115Ala, Arg43Gln, and Lys148Gln. Analysis of the data confirms the proposed location of an effector binding site in a cluster of positively charged amino acid residues including the side chains of Arg43, Lys146 (subunit A), Lys112, and Lys115 (subunit B). Lys112 is supposed to play a key role in forming contacts with the phosphate groups of the three studied effectors. PMID:17309443

Rodina, E V; Vorobyeva, N N; Kurilova, S A; Sitnik, T S; Nazarova, T I

2007-01-01

132

Nitrogen controls in planta expression of Cladosporium fulvum Avr9 but no other effector genes  

Microsoft Academic Search

During growth on its host tomato, the apoplast-colonizing fungal pathogen Cladosporium fulvum secretes several effector proteins. The expression of the Avr9 gene encoding one of these effector proteins has previously been shown to be strongly induced in vitro during nitrogen deprivation. This led to the hypothesis that expression of additional effector genes in C. fulvum could be triggered by nitrogen

BART P. H. J. THOMMA; MELVIN D. BOLTON; PIERRE-HENRI CLERGEOT; Wit de P. J. G. M

2006-01-01

133

Ashley Richards Dissertation Proposal 2013 Eukaryotic post-translational modification of bacterial effectors  

E-print Network

. pneumophila in order to promote growth and replication. Many injected bacterial effectors are modified of bacterial effectors Keywords: asparagine hydroxylation, Legionella pneumophila, Yersinia pestis, bacterial can also be found in other injected bacterial effectors such as, the Outer Protein M (Yop

Heller, Paul

134

Deletions in the Repertoire of Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Genes Reveal Functional Overlap among Effectors  

PubMed Central

The ?-proteobacterial plant pathogen Pseudomonas syringae pv. tomato DC3000 uses the type III secretion system to inject ca. 28 Avr/Hop effector proteins into plants, which enables the bacterium to grow from low inoculum levels to produce bacterial speck symptoms in tomato, Arabidopsis thaliana, and (when lacking hopQ1-1) Nicotiana benthamiana. The effectors are collectively essential but individually dispensable for the ability of the bacteria to defeat defenses, grow, and produce symptoms in plants. Eighteen of the effector genes are clustered in six genomic islands/islets. Combinatorial deletions involving these clusters and two of the remaining effector genes revealed a redundancy-based structure in the effector repertoire, such that some deletions diminished growth in N. benthamiana only in combination with other deletions. Much of the ability of DC3000 to grow in N. benthamiana was found to be due to five effectors in two redundant-effector groups (REGs), which appear to separately target two high-level processes in plant defense: perception of external pathogen signals (AvrPto and AvrPtoB) and deployment of antimicrobial factors (AvrE, HopM1, HopR1). Further support for the membership of HopR1 in the same REG as AvrE was gained through bioinformatic analysis, revealing the existence of an AvrE/DspA/E/HopR effector superfamily, which has representatives in virtually all groups of proteobacterial plant pathogens that deploy type III effectors. PMID:19381254

Kvitko, Brian H.; Park, Duck Hwan; Velásquez, André C.; Wei, Chia-Fong; Russell, Alistair B.; Martin, Gregory B.; Schneider, David J.; Collmer, Alan

2009-01-01

135

A smart end-effector for assembly of space truss structures  

NASA Technical Reports Server (NTRS)

A unique facility, the Automated Structures Research Laboratory, is being used to investigate robotic assembly of truss structures. A special-purpose end-effector is used to assemble structural elements into an eight meter diameter structure. To expand the capabilities of the facility to include construction of structures with curved surfaces from straight structural elements of different lengths, a new end-effector has been designed and fabricated. This end-effector contains an integrated microprocessor to monitor actuator operations through sensor feedback. This paper provides an overview of the automated assembly tasks required by this end-effector and a description of the new end-effector's hardware and control software.

Doggett, William R.; Rhodes, Marvin D.; Wise, Marion A.; Armistead, Maurice F.

1992-01-01

136

Interferon-inducible effector mechanisms in cell-autonomous immunity  

PubMed Central

Interferons (IFNs) induce the expression of hundreds of genes as part of an elaborate antimicrobial programme designed to combat infection in all nucleated cells — a process termed cell-autonomous immunity. As described in this Review, recent genomic and subgenomic analyses have begun to assign functional properties to novel IFN-inducible effector proteins that restrict bacteria, protozoa and viruses in different subcellular compartments and at different stages of the pathogen life cycle. Several newly described host defence factors also participate in canonical oxidative and autophagic pathways by spatially coordinating their activities to enhance microbial killing. Together, these IFN-induced effector networks help to confer vertebrate host resistance to a vast and complex microbial world. PMID:22531325

MacMicking, John D.

2014-01-01

137

Interchangeable end effector tools utilized on the protoflight manipulator arm  

NASA Technical Reports Server (NTRS)

A subset of teleoperator and effector tools was designed, fabricated, delivered and successfully demonstrated on the Marshall Space Flight Center (MSFC) protoflight manipulator arm (PFMA). The tools delivered included a rotary power tool with interchangeable collets and two fluid coupling mate/demate tools; one for a Fairchild coupling and the other for a Purolator coupling. An electrical interface connector was also provided for the rotary power tool. A tool set, from which the subset was selected, for performing on-orbit satellite maintenance was identified and conceptionally designed. Maintenance requirements were synthesized, evaluated and prioritized to develop design requirements for a set of end effector tools representative of those needed to provide on-orbit maintenance of satellites to be flown in the 1986 to 2000 timeframe.

1987-01-01

138

Multiple recognition of RXLR effectors is associated with nonhost resistance of pepper against Phytophthora infestans.  

PubMed

Nonhost resistance (NHR) is a plant immune response to resist most pathogens. The molecular basis of NHR is poorly understood, but recognition of pathogen effectors by immune receptors, a response known as effector-triggered immunity, has been proposed as a component of NHR. We performed transient expression of 54 Phytophthora infestansRXLR effectors in pepper (Capsicum annuum) accessions. We used optimized heterologous expression methods and analyzed the inheritance of effector-induced cell death in an F2 population derived from a cross between two pepper accessions. Pepper showed a localized cell death response upon inoculation with P. infestans, suggesting that recognition of effectors may contribute to NHR in this system. Pepper accessions recognized as many as 36 effectors. Among the effectors, PexRD8 and Avrblb2 induced cell death in a broad range of pepper accessions. Segregation of effector-induced cell death in an F2 population derived from a cross between two pepper accessions fit 15:1, 9:7 or 3:1 ratios, depending on the effector. Our genetic data suggest that a single or two independent/complementary dominant genes are involved in the recognition of RXLR effectors. Multiple loci recognizing a series of effectors may underpin NHR of pepper to P. infestans and confer resistance durability. PMID:24889686

Lee, Hyun-Ah; Kim, Shin-Young; Oh, Sang-Keun; Yeom, Seon-In; Kim, Saet-Byul; Kim, Myung-Shin; Kamoun, Sophien; Choi, Doil

2014-08-01

139

Multiple recognition of RXLR effectors is associated with nonhost resistance of pepper against Phytophthora infestans  

PubMed Central

Nonhost resistance (NHR) is a plant immune response to resist most pathogens. The molecular basis of NHR is poorly understood, but recognition of pathogen effectors by immune receptors, a response known as effector-triggered immunity, has been proposed as a component of NHR. We performed transient expression of 54 Phytophthora infestansRXLR effectors in pepper (Capsicum annuum) accessions. We used optimized heterologous expression methods and analyzed the inheritance of effector-induced cell death in an F2 population derived from a cross between two pepper accessions. Pepper showed a localized cell death response upon inoculation with P. infestans, suggesting that recognition of effectors may contribute to NHR in this system. Pepper accessions recognized as many as 36 effectors. Among the effectors, PexRD8 and Avrblb2 induced cell death in a broad range of pepper accessions. Segregation of effector-induced cell death in an F2 population derived from a cross between two pepper accessions fit 15 : 1, 9 : 7 or 3 : 1 ratios, depending on the effector. Our genetic data suggest that a single or two independent/complementary dominant genes are involved in the recognition of RXLR effectors. Multiple loci recognizing a series of effectors may underpin NHR of pepper to P. infestans and confer resistance durability. PMID:24889686

Lee, Hyun-Ah; Kim, Shin-Young; Oh, Sang-Keun; Yeom, Seon-In; Kim, Saet-Byul; Kim, Myung-Shin; Kamoun, Sophien; Choi, Doil

2014-01-01

140

In vivo inhibition of human CD19 targeted effector T cells by natural T regulatory cells in a xenotransplant murine model of B cell malignancy  

PubMed Central

Human T cells genetically modified to express chimeric antigen receptors (CARs) specific to the B cell tumor antigen CD19 can successfully eradicate systemic human CD19+ tumors in immunocompromised SCID-Beige mice. However, in the clinical setting, CD4+ CD25hi T regulatory cells (Tregs) present within the tumor microenvironment are potent suppressors of tumor-targeted effector T cells. In order to assess the impact of Tregs on CAR-modified T cells in the SCID-Beige xenotransplant model, we isolated, genetically targeted and expanded natural T regulatory cells (nTregs). In vitro, nTregs, modified to express CD19 targeted CARs efficiently inhibited the proliferation of activated human T cells, as well as the capacity of CD19-targeted 19-28z+ effector T cells to lyse CD19+ Raji tumor cells. Intravenous infusion of CD19-targeted nTregs into SCID-Beige mice with systemic Raji tumors traffic to sites of tumor and recapitulate a clinically relevant hostile tumor microenvironment. Anti-tumor efficacy of subsequently infused 19-28z+ effector T cells was fully abrogated as assessed by long-term survival of treated mice. Optimal suppression by genetically targeted nTregs was dependent on nTreg to effector T cell ratios and in vivo nTreg activation. Prior infusion of cyclophosphamide in the setting of this nTreg-mediated hostile microenvironment was able to restore the anti-tumor activity of subsequently infused 19-28z+ effector T cells through the eradication of tumor targeted nTregs. These findings have significant implications on the design of future clinical trials utilizing CAR-based adoptive T cell therapies of cancer. PMID:21487038

Lee, James; Hayman, Erik; Pegram, Hollie; Santos, Elmer; Heller, Glen; Sadelain, Michel; Brentjens, Renier J.

2011-01-01

141

In vivo inhibition of human CD19-targeted effector T cells by natural T regulatory cells in a xenotransplant murine model of B cell malignancy.  

PubMed

Human T cells genetically modified to express chimeric antigen receptors (CAR) specific to the B cell tumor antigen CD19 can successfully eradicate systemic human CD19(+) tumors in immunocompromised SCID (severe combined immunodeficient)-Beige mice. However, in the clinical setting, CD4(+) CD25(hi) T regulatory cells (Treg) present within the tumor microenvironment may be potent suppressors of tumor-targeted effector T cells. In order to assess the impact of Tregs on CAR-modified T cells in the SCID-Beige xenotransplant model, we isolated, genetically targeted and expanded natural T regulatory cells (nTreg). In vitro nTregs modified to express CD19-targeted CARs efficiently inhibited the proliferation of activated human T cells, as well as the capacity of CD19-targeted 19-28z(+) effector T cells to lyse CD19(+) Raji tumor cells. Intravenous infusion of CD19-targeted nTregs into SCID-Beige mice with systemic Raji tumors traffic to sites of tumor and recapitulate a clinically relevant hostile tumor microenvironment. Antitumor efficacy of subsequently infused 19-28z(+) effector T cells was fully abrogated as assessed by long-term survival of treated mice. Optimal suppression by genetically targeted nTregs was dependent on nTreg to effector T-cell ratios and in vivo nTreg activation. Prior infusion of cyclophosphamide in the setting of this nTreg-mediated hostile microenvironment was able to restore the antitumor activity of subsequently infused 19-28z(+) effector T cells through the eradication of tumor-targeted nTregs. These findings have significant implications for the design of future clinical trials utilizing CAR-based adoptive T-cell therapies of cancer. PMID:21487038

Lee, James C; Hayman, Erik; Pegram, Hollie J; Santos, Elmer; Heller, Glenn; Sadelain, Michel; Brentjens, Renier

2011-04-15

142

Platelets as Cellular Effectors of Inflammation in Vascular Diseases  

PubMed Central

Platelets are chief effector cells in hemostasis. In addition, they are multifaceted inflammatory cells with functions that span the continuum from innate immune responses to adaptive immunity. Activated platelets have key “thromboinflammatory” activities in a variety of vascular disorders and vasculopathies. Recently-identified inflammatory and immune activities provide insights into the biology of these versatile blood cells that are directly relevant to human vascular diseases. PMID:23704217

Rondina, Matthew T.; Weyrich, Andrew S.; Zimmerman, Guy A.

2013-01-01

143

A nematode effector protein similar to annexins in host plants.  

PubMed

Nematode parasitism genes encode secreted effector proteins that play a role in host infection. A homologue of the expressed Hg4F01 gene of the root-parasitic soybean cyst nematode, Heterodera glycines, encoding an annexin-like effector, was isolated in the related Heterodera schachtii to facilitate use of Arabidopsis thaliana as a model host. Hs4F01 and its protein product were exclusively expressed within the dorsal oesophageal gland secretory cell in the parasitic stages of H. schachtii. Hs4F01 had a 41% predicted amino acid sequence identity to the nex-1 annexin of C. elegans and 33% identity to annexin-1 (annAt1) of Arabidopsis, it contained four conserved domains typical of the annexin family of calcium and phospholipid binding proteins, and it had a predicted signal peptide for secretion that was present in nematode annexins of only Heterodera spp. Constitutive expression of Hs4F01 in wild-type Arabidopsis promoted hyper-susceptibility to H. schachtii infection. Complementation of an AnnAt1 mutant by constitutive expression of Hs4F01 reverted mutant sensitivity to 75 mM NaCl, suggesting a similar function of the Hs4F01 annexin-like effector in the stress response by plant cells. Yeast two-hybrid assays confirmed a specific interaction between Hs4F01 and an Arabidopsis oxidoreductase member of the 2OG-Fe(II) oxygenase family, a type of plant enzyme demonstrated to promote susceptibility to oomycete pathogens. RNA interference assays that expressed double-stranded RNA complementary to Hs4F01 in transgenic Arabidopsis specifically decreased parasitic nematode Hs4F01 transcript levels and significantly reduced nematode infection levels. The combined data suggest that nematode secretion of an Hs4F01 annexin-like effector into host root cells may mimic plant annexin function during the parasitic interaction. PMID:19887499

Patel, Nrupali; Hamamouch, Noureddine; Li, Chunying; Hewezi, Tarek; Hussey, Richard S; Baum, Thomas J; Mitchum, Melissa G; Davis, Eric L

2010-01-01

144

B Lymphocytes as Effector Cells in the Immunotherapy of Cancer  

PubMed Central

Over the years, the role of B cells in the host immune response to malignancy has been overshadowed by our focus on T cells. Nevertheless, B cells play important roles as antigen-presenting cells and in the production of antibodies. Furthermore, B cells can function as effector cells that mediate tumor destruction on their own. This review will highlight the various functions of B cells that are involved in the host response to tumor. PMID:21898417

Namm, Jukes P.; Li, Qiao; Lao, Xiangming; Lubman, David M.; He, Jintang; Liu, Yashu; Zhu, Jianhui; Wei, Shuang; Chang, Alfred E.

2015-01-01

145

Distinct in vivo roles of CD80 and CD86 in the effector T-cell responses inducing antigen-induced arthritis  

PubMed Central

CD80 and CD86 play a critical role in the initiation of T-cell responses. However, their role in the in vivo effector CD4+ T-cell responses has been less extensively investigated. The current studies have examined the functional relevance of CD80 and CD86 in the effector CD4+ T-cell responses inducing antigen-induced arthritis. Arthritis was induced in C57BL/6 mice by sensitization to methylated bovine serum albumin (mBSA) on day 0, booster immunization (day 7) and intra-articular injection of mBSA (day 21). Control or anti-CD80 and/or anti-CD86 monoclonal antibodies were administered from day 21 to day 28. Arthritis severity and immune responses were assessed on day 28. The development of arthritis was significantly suppressed by inhibition of CD80 or CD86. Blockade of both CD80 and CD86 caused a trend towards reduced disease severity compared to control antibody-treated mice. Neutralization of CD80 attenuated accumulation of CD4+ T cells in joints and enhanced splenocyte production and circulating levels of interleukin-4. Inhibition of CD86 or both CD80 and CD86 reduced T-cell accumulation in joints without affecting T helper type 1/type 2 (Th1/Th2) differentiation or antibody levels. Blockade of CD86, and not CD80, significantly suppressed splenocyte interleukin-17 (IL-17) production. These results provide further in vivo evidence that CD80 and CD86 play important pathogenic roles in effector T-cell responses. CD80 exacerbates arthritis by downregulating systemic levels of IL-4 and increasing T-cell accumulation in joints without affecting IL-17 production. CD86 enhances disease severity by upregulating IL-17 production and increasing the accumulation of effector T cells in joints without affecting Th1/Th2 development. PMID:18217945

Odobasic, Dragana; Leech, Michelle T; Xue, Jin R; Holdsworth, Stephen R

2008-01-01

146

Chlamydial Effector Proteins Localized to the Host Cell Cytoplasmic Compartment?  

PubMed Central

Disease-causing microbes utilize various strategies to modify their environment in order to create a favorable location for growth and survival. Gram-negative bacterial pathogens often use specialized secretion systems to translocate effector proteins directly into the cytosol of the eukaryotic cells they infect. These bacterial proteins are responsible for modulating eukaryotic cell functions. Identification of the bacterial effectors has been a critical step toward understanding the molecular basis for the pathogenesis of the bacteria that use them. Chlamydiae are obligate intracellular bacterial pathogens that have a type III secretion system believed to translocate virulence effector proteins into the cytosol of their host cells. Selective permeabilization of the eukaryotic cell membrane was used in conjunction with metabolic labeling of bacterial proteins to identify chlamydial proteins that localize within the cytosol of infected cells. More than 20 Chlamydia trachomatis and C. pneumoniae proteins were detected within the cytoplasmic compartment of infected cells. While a number of cytosolic proteins were shared, others were unique to each species, suggesting that variation among cytosolic chlamydial proteins contributes to the differences in the pathogenesis of the chlamydial species. The spectrum of chlamydial proteins exported differed concomitant with the progress of the developmental cycle. These data confirm that a dynamic relationship exists between Chlamydia and its host and that translocation of bacterial proteins into the cytosol is developmentally dependent. PMID:18710866

Kleba, Betsy; Stephens, Richard S.

2008-01-01

147

Rapamycin-resistant effector T-cell therapy.  

PubMed

Pharmacologic inhibition of the mechanistic target of rapamycin (mTOR) represents a stress test for tumor cells and T cells. Mechanisms exist that allow cells to survive this stress, including suboptimal target block, alternative signaling pathways, and autophagy. Rapamycin-resistant effector T (T-Rapa) cells have an altered phenotype that associates with increased function. Ex vivo rapamycin, when used in combination with polarizing cytokines and antigen-presenting-cell free costimulation, is a flexible therapeutic approach as polarization to T-helper 1 (Th1)- or Th2-type effectors is possible. Murine T-Rapa cells skewed toward a Th2-type prevented graft rejection and graft-versus-host disease (GVHD) more potently than control Th2 cells and effectively balanced GVHD and graft-versus-tumor (GVT) effects. A phase II clinical trial using low-intensity allogeneic hematopoietic cell transplantation demonstrated that interleukin-4 polarized human T-Rapa cells had a mixed Th2/Th1 phenotype; T-Rapa cell recipients had a balanced Th2/Th1 cytokine profile, conversion of mixed chimerism toward full donor chimerism, and a potentially favorable balance between GVHD and GVT effects. In addition, a phase I clinical trial evaluating autologous T-Rapa cells skewed toward a Th1- and Tc1-type is underway. Use of ex vivo rapamycin to modulate effector T-cell function represents a promising new approach to transplantation therapy. PMID:24329799

Fowler, Daniel H

2014-01-01

148

Herbivore exploits orally secreted bacteria to suppress plant defenses  

PubMed Central

Induced plant defenses in response to herbivore attack are modulated by cross-talk between jasmonic acid (JA)- and salicylic acid (SA)-signaling pathways. Oral secretions from some insect herbivores contain effectors that overcome these antiherbivore defenses. Herbivores possess diverse microbes in their digestive systems and these microbial symbionts can modify plant–insect interactions; however, the specific role of herbivore-associated microbes in manipulating plant defenses remains unclear. Here, we demonstrate that Colorado potato beetle (Leptinotarsa decemlineata) larvae exploit bacteria in their oral secretions to suppress antiherbivore defenses in tomato (Solanum lycopersicum). We found that antibiotic-untreated larvae decreased production of JA and JA-responsive antiherbivore defenses, but increased SA accumulation and SA-responsive gene expression. Beetles benefit from down-regulating plant defenses by exhibiting enhanced larval growth. In SA-deficient plants, suppression was not observed, indicating that suppression of JA-regulated defenses depends on the SA-signaling pathway. Applying bacteria isolated from larval oral secretions to wounded plants confirmed that three microbial symbionts belonging to the genera Stenotrophomonas, Pseudomonas, and Enterobacter are responsible for defense suppression. Additionally, reinoculation of these bacteria to antibiotic-treated larvae restored their ability to suppress defenses. Flagellin isolated from Pseudomonas sp. was associated with defense suppression. Our findings show that the herbivore exploits symbiotic bacteria as a decoy to deceive plants into incorrectly perceiving the threat as microbial. By interfering with the normal perception of herbivory, beetles can evade antiherbivore defenses of its host. PMID:24019469

Chung, Seung Ho; Rosa, Cristina; Scully, Erin D.; Peiffer, Michelle; Tooker, John F.; Hoover, Kelli; Luthe, Dawn S.; Felton, Gary W.

2013-01-01

149

ANTIGEN SPECIFIC ANTIBODY COATED EXOSOME-LIKE NANOVESICLES DELIVER SUPPRESSOR T CELL miRNA-150 TO EFFECTOR T CELLS IN CONTACT SENSITIVITY  

PubMed Central

Background T cell tolerance of allergic cutaneous contact sensitivity (CS) induced in mice by high doses of reactive hapten is mediated by suppressor cells that release antigen-specific suppressive nanovesicles. Objective To determine the mechanism(s) of immune suppression mediated by the nanovesicles. Methods T cell tolerance was induced by i.v. injections of hapten conjugated to self antigens of syngeneic erythrocytes and subsequent contact immunization with the same hapten. Lymph node and spleen cells from tolerized or control donors were harvested and cultured to produce a supernatant containing suppressive nanovesicles that were isolated for testing in active and adoptive cell transfer models of CS. Results Tolerance was shown due to exosome-like nanovesicles in the supernatant of CD8+ suppressor T cells that were not Treg. Antigen specificity of the suppressive nanovesicles was conferred by a surface coat of antibody light chains, or possibly whole antibody, allowing targeted delivery of selected inhibitory miRNA-150 to CS effector T cells. Nanovesicles also inhibited CS in actively sensitized mice after systemic injection at the peak of the responses. The role of antibody and miRNA-150 was established by tolerizing either panimmunoglobulin deficient JH-/- or miRNA-150-/- mice that produced non-suppressive nanovesicles. These nanovesicles could be made suppressive by adding antigen-specific antibody light chains or miRNA-150, respectively. Conclusions This is the first example of T cell regulation via systemic transit of exosome-like nanovesicles delivering a chosen inhibitory miRNA to target effector T cells in an antigen-specific manner by a surface coating of antibody light chains. PMID:23727037

Bryniarski, Krzysztof; Ptak, Wlodzimierz; Jayakumar, Asha; Püllmann, Kerstin; Caplan, Michael J.; Chairoungdua, Arthit; Lu, Jun; Adams, Brian; Sikora, Emilia; Nazimek, Katarzyna; Marquez, Susanna; Kleinstein, Steven H.; Sangwung, Panjamaporn; Iwakiri, Yasuko; Delgato, Eric; Redegeld, Frank; Blokhuis, Bart R.; Wojcikowski, Jacek; Daniel, Anna Wladyslawa; Kormelink, Tom Groot; Askenase, Philip W.

2014-01-01

150

IEEE TRANSACTIONS ON ROBOTICS, VOL. 30, NO. 1, FEBRUARY 2014 125 Locating End-Effector Tips in Robotic Micromanipulation  

E-print Network

-effector positions, autofocusing and quad-tree search to locate an end-effector tip, and, finally, visual servoingIEEE TRANSACTIONS ON ROBOTICS, VOL. 30, NO. 1, FEBRUARY 2014 125 Locating End-Effector Tips, and Yu Sun Abstract--In robotic micromanipulation, end-effector tips must be first located under

Sun, Yu

151

Phytophthora sojae Avirulence Effector Avr3b is a Secreted NADH and ADP-ribose Pyrophosphorylase that Modulates Plant Immunity  

PubMed Central

Plants have evolved pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) to protect themselves from infection by diverse pathogens. Avirulence (Avr) effectors that trigger plant ETI as a result of recognition by plant resistance (R) gene products have been identified in many plant pathogenic oomycetes and fungi. However, the virulence functions of oomycete and fungal Avr effectors remain largely unknown. Here, we combined bioinformatics and genetics to identify Avr3b, a new Avr gene from Phytophthora sojae, an oomycete pathogen that causes soybean root rot. Avr3b encodes a secreted protein with the RXLR host-targeting motif and C-terminal W and Nudix hydrolase motifs. Some isolates of P. sojae evade perception by the soybean R gene Rps3b through sequence mutation in Avr3b and lowered transcript accumulation. Transient expression of Avr3b in Nicotiana benthamiana increased susceptibility to P. capsici and P. parasitica, with significantly reduced accumulation of reactive oxygen species (ROS) around invasion sites. Biochemical assays confirmed that Avr3b is an ADP-ribose/NADH pyrophosphorylase, as predicted from the Nudix motif. Deletion of the Nudix motif of Avr3b abolished enzyme activity. Mutation of key residues in Nudix motif significantly impaired Avr3b virulence function but not the avirulence activity. Some Nudix hydrolases act as negative regulators of plant immunity, and thus Avr3b might be delivered into host cells as a Nudix hydrolase to impair host immunity. Avr3b homologues are present in several sequenced Phytophthora genomes, suggesting that Phytophthora pathogens might share similar strategies to suppress plant immunity. PMID:22102810

Dong, Suomeng; Yin, Weixiao; Kong, Guanghui; Yang, Xinyu; Qutob, Dinah; Chen, Qinghe; Kale, Shiv D.; Sui, Yangyang; Zhang, Zhengguang; Dou, Daolong; Zheng, Xiaobo; Gijzen, Mark; M. Tyler, Brett; Wang, Yuanchao

2011-01-01

152

The Salmonella Effector SteA Contributes to the Control of Membrane Dynamics of Salmonella-Containing Vacuoles  

PubMed Central

Salmonella enterica serovar Typhimurium is a bacterial pathogen causing gastroenteritis in humans and a typhoid-like systemic disease in mice. S. Typhimurium virulence is related to its capacity to multiply intracellularly within a membrane-bound compartment, the Salmonella-containing vacuole (SCV), and depends on type III secretion systems that deliver bacterial effector proteins into host cells. Here, we analyzed the cellular function of the Salmonella effector SteA. We show that, compared to cells infected by wild-type S. Typhimurium, cells infected by ?steA mutant bacteria displayed fewer Salmonella-induced filaments (SIFs), an increased clustering of SCVs, and morphologically abnormal vacuoles containing more than one bacterium. The increased clustering of SCVs and the appearance of vacuoles containing more than one bacterium were suppressed by inhibition of the activity of the microtubule motor dynein or kinesin-1. Clustering and positioning of SCVs are controlled by the effectors SseF and SseG, possibly by helping to maintain a balanced activity of microtubule motors on the bacterial vacuoles. Deletion of steA in S. Typhimurium ?sseF or ?sseG mutants revealed that SteA contributes to the characteristic scattered distribution of ?sseF or ?sseG mutant SCVs in infected cells. Overall, this shows that SteA participates in the control of SCV membrane dynamics. Moreover, it indicates that SteA is functionally linked to SseF and SseG and suggests that it might contribute directly or indirectly to the regulation of microtubule motors on the bacterial vacuoles. PMID:24778114

Domingues, Lia; Holden, David W.

2014-01-01

153

Suppression of polymorphonuclear (PMN) and monocyte-mediated inhibition of Candida albicans growth by delta-9-tetrahydrocannabinol  

SciTech Connect

This study was an in vitro attempt to identify the effector cells responsible for growth inhibition of the opportunistic fungus, candida albicans, and to determine if THC or another marijuana derivatives, 11-hydroxyTHC, would adversely affect their function. Using a 24h radiolabel assay, the authors found that growth inhibition of C. albicans was primarily mediated by PMN and monocytes that could be isolated normal human peripheral blood. Both effector cell types caused almost complete inhibition of Candida growth at effector/target ratio of 300/1 and inhibition was often still seen at 30/1-. Incubation of PMN, PBL, or monocytes for 1 hr at 37C with THC or 11-hydroxyTHC caused a marked suppression of function in all 3 cell populations. Maximal suppression was obtained with 7.5-10..mu..g/ml of the drugs in medium containing 10% fetal bovine serum (FBS) or with 2-4..mu..g/ml in 1% FBS. These drug concentrations did not affect lymphoid cell viability or candida growth in the absence of lymphoid effector cells. Marijuana derivatives, therefore, are doubly dangerous in that opportunistic fungi such as C. albicans can grow in their presence while the effector cells that control fungal growth are readily inactivated.

Djeu, J.Y.; Parapanios, A.; Halkias, D.; Friedman, H.

1986-03-05

154

Fire Suppression and Response  

NASA Technical Reports Server (NTRS)

This report is concerned with the following topics regarding fire suppression:What is the relative effectiveness of candidate suppressants to extinguish a representative fire in reduced gravity, including high-O2 mole fraction, low -pressure environments? What are the relative advantages and disadvantages of physically acting and chemically-acting agents in spacecraft fire suppression? What are the O2 mole fraction and absolute pressure below which a fire cannot exist? What effect does gas-phase radiation play in the overall fire and post-fire environments? Are the candidate suppressants effective to extinguish fires on practical solid fuels? What is required to suppress non-flaming fires (smoldering and deep seated fires) in reduced gravity? How can idealized space experiment results be applied to a practical fire scenario? What is the optimal agent deployment strategy for space fire suppression?

Ruff, Gary A.

2004-01-01

155

Dopamine inhibits the effector functions of activated NK cells via the upregulation of the D5 receptor.  

PubMed

Several lines of evidence indicate that dopamine (DA) plays a key role in the cross-talk between the nervous and immune systems. In this study, we disclose a novel immune-regulatory role for DA: inhibition of effector functions of activated NK lymphocytes via the selective upregulation of the D5 dopaminergic receptor in response to prolonged cell stimulation with rIL-2. Indeed, engagement of this D1-like inhibitory receptor following binding with DA suppresses NK cell proliferation and synthesis of IFN-?. The inhibition of IFN-? production occurs through blocking the repressor activity of the p50/c-REL dimer of the NF-?B complex. Indeed, the stimulation of the D5 receptor on rIL-2-activated NK cells inhibits the binding of p50 to the microRNA 29a promoter, thus inducing a de novo synthesis of this miRNA. In turn, the increased levels of microRNA 29a were inversely correlated with the ability of NK cells to produce IFN-?. Taken together, our findings demonstrated that DA switches off activated NK cells, thus representing a checkpoint exerted by the nervous system to control the reactivity of these innate immune effectors in response to activation stimuli and to avoid the establishment of chronic and pathologic inflammatory processes. PMID:25127864

Mikulak, Joanna; Bozzo, Luisa; Roberto, Alessandra; Pontarini, Elena; Tentorio, Paolo; Hudspeth, Kelly; Lugli, Enrico; Mavilio, Domenico

2014-09-15

156

Nuf, a Rab11 effector, maintains cytokinetic furrow integrity by promoting local actin polymerization  

PubMed Central

Plasma membrane ingression during cytokinesis involves both actin remodeling and vesicle-mediated membrane addition. Vesicle-based membrane delivery from the recycling endosome (RE) has an essential but ill-defined involvement in cytokinesis. In the Drosophila melanogaster early embryo, Nuf (Nuclear fallout), a Rab11 effector which is essential for RE function, is required for F-actin and membrane integrity during furrow ingression. We find that in nuf mutant embryos, an initial loss of F-actin at the furrow is followed by loss of the associated furrow membrane. Wild-type embryos treated with Latrunculin A or Rho inhibitor display similar defects. Drug- or Rho-GTP–induced increase of actin polymerization or genetically mediated decrease of actin depolymerization suppresses the nuf mutant F-actin and membrane defects. We also find that RhoGEF2 does not properly localize at the furrow in nuf mutant embryos and that RhoGEF2–Rho1 pathway components show strong specific genetic interactions with Nuf. We propose a model in which RE-derived vesicles promote furrow integrity by regulating the rate of actin polymerization through the RhoGEF2–Rho1 pathway. PMID:18644888

Cao, Jian; Albertson, Roger; Riggs, Blake; Field, Christine M.; Sullivan, William

2008-01-01

157

The Drosophila effector caspase Dcp-1 regulates mitochondrial dynamics and autophagic flux via SesB.  

PubMed

Increasing evidence reveals that a subset of proteins participates in both the autophagy and apoptosis pathways, and this intersection is important in normal physiological contexts and in pathological settings. In this paper, we show that the Drosophila effector caspase, Drosophila caspase 1 (Dcp-1), localizes within mitochondria and regulates mitochondrial morphology and autophagic flux. Loss of Dcp-1 led to mitochondrial elongation, increased levels of the mitochondrial adenine nucleotide translocase stress-sensitive B (SesB), increased adenosine triphosphate (ATP), and a reduction in autophagic flux. Moreover, we find that SesB suppresses autophagic flux during midoogenesis, identifying a novel negative regulator of autophagy. Reduced SesB activity or depletion of ATP by oligomycin A could rescue the autophagic defect in Dcp-1 loss-of-function flies, demonstrating that Dcp-1 promotes autophagy by negatively regulating SesB and ATP levels. Furthermore, we find that pro-Dcp-1 interacts with SesB in a nonproteolytic manner to regulate its stability. These data reveal a new mitochondrial-associated molecular link between nonapoptotic caspase function and autophagy regulation in vivo. PMID:24862573

DeVorkin, Lindsay; Go, Nancy Erro; Hou, Ying-Chen Claire; Moradian, Annie; Morin, Gregg B; Gorski, Sharon M

2014-05-26

158

Transgenic Plants That Express the Phytoplasma Effector SAP11 Show Altered Phosphate Starvation and Defense Responses1[W][OPEN  

PubMed Central

Phytoplasmas have the smallest genome among bacteria and lack many essential genes required for biosynthetic and metabolic functions, making them unculturable, phloem-limited plant pathogens. In this study, we observed that transgenic Arabidopsis (Arabidopsis thaliana) expressing the secreted Aster Yellows phytoplasma strain Witches’ Broom protein11 shows an altered root architecture, similarly to the disease symptoms of phytoplasma-infected plants, by forming hairy roots. This morphological change is paralleled by an accumulation of cellular phosphate (Pi) and an increase in the expression levels of Pi starvation-induced genes and microRNAs. In addition to the Pi starvation responses, we found that secreted Aster Yellows phytoplasma strain Witches’ Broom protein11 suppresses salicylic acid-mediated defense responses and enhances the growth of a bacterial pathogen. These results contribute to an improved understanding of the role of phytoplasma effector SAP11 and provide new insights for understanding the molecular basis of plant-pathogen interactions. PMID:24464367

Lu, Yen-Ting; Li, Meng-Ying; Cheng, Kai-Tan; Tan, Choon Meng; Su, Li-Wen; Lin, Wei-Yi; Shih, Hsien-Tzung; Chiou, Tzyy-Jen; Yang, Jun-Yi

2014-01-01

159

Effector candidates in the secretome of Piriformospora indica, a ubiquitous plant-associated fungus  

PubMed Central

One of the emerging systems in plant–microbe interaction is the study of proteins, referred to as effectors, secreted by microbes in order to modulate host cells function and structure and to promote microbial growth on plant tissue. Current knowledge on fungal effectors derives mainly from biotrophic and hemibiotrophic plant fungal pathogens that have a limited host range. Here, we focus on effectors of Piriformospora indica, a soil borne endophyte forming intimate associations with roots of a wide range of plant species. Complete genome sequencing provides an opportunity to investigate the role of effectors during the interaction of this mutualistic fungus with plants. We describe in silico analyses to predict effectors of P. indica and we explore effector features considered here to mine a high priority protein list for functional analysis. PMID:23874344

Rafiqi, Maryam; Jelonek, Lukas; Akum, Ndifor F.; Zhang, Feng; Kogel, Karl-Heinz

2013-01-01

160

Galaxy as a platform for identifying candidate pathogen effectors.  

PubMed

The Galaxy web platform provides an integrated system for its users to run multiple computational tools, linking their output in order to perform sophisticated analysis without requiring any programming or installation of software beyond a modern web-browser. Analyses can be saved as reusable workflows, and shared with other Galaxy users, allowing them to easily perform the same analysis or protocol on their own data.We describe example Galaxy workflows for the identification of candidate pathogen effector proteins. Our main example focuses on nematode plant pathogens where signal peptide and transmembrane prediction tools are used to identify predicted secreted proteins. PMID:24643548

Cock, Peter J A; Pritchard, Leighton

2014-01-01

161

Tool use and the distalization of the end-effector  

PubMed Central

We review recent neurophysiological data from macaques and humans suggesting that the use of tools extends the internal representation of the actor’s hand, and relate it to our modeling of the visual control of grasping. We introduce the idea that, in addition to extending the body schema to incorporate the tool, tool use involves distalization of the end-effector from hand to tool. Different tools extend the body schema in different ways, with a displaced visual target and a novel, task-specific processing of haptic feedback to the hand. This distalization is critical in order to exploit the unique functional capacities engendered by complex tools. PMID:19347356

Bonaiuto, James B.; Jacobs, Stéphane; Frey, Scott H.

2009-01-01

162

Functions and requirements for the INEL light duty utility arm sampler end effector  

SciTech Connect

This sampler end effector system functions and requirements document defines the system functions that the end effector must perform as well as the requirements the design must meet. Safety, quality assurance, operations, environmental conditions, and regulatory requirements have been considered. The main purpose of this document is to provide a basis for the end effector engineering, design, and fabrication activities. The document shall be the living reference document to initiate the development activities and will be updated as system technologies are finalized.

Pace, D.P.; Barnes, G.E.

1995-02-01

163

A Plethora of Virulence Strategies Hidden Behind Nuclear Targeting of Microbial Effectors  

PubMed Central

Plant immune responses depend on the ability to couple rapid recognition of the invading microbe to an efficient response. During evolution, plant pathogens have acquired the ability to deliver effector molecules inside host cells in order to manipulate cellular and molecular processes and establish pathogenicity. Following translocation into plant cells, microbial effectors may be addressed to different subcellular compartments. Intriguingly, a significant number of effector proteins from different pathogenic microorganisms, including viruses, oomycetes, fungi, nematodes, and bacteria, is targeted to the nucleus of host cells. In agreement with this observation, increasing evidence highlights the crucial role played by nuclear dynamics, and nucleocytoplasmic protein trafficking during a great variety of analyzed plant–pathogen interactions. Once in the nucleus, effector proteins are able to manipulate host transcription or directly subvert essential host components to promote virulence. Along these lines, it has been suggested that some effectors may affect histone packing and, thereby, chromatin configuration. In addition, microbial effectors may either directly activate transcription or target host transcription factors to alter their regular molecular functions. Alternatively, nuclear translocation of effectors may affect subcellular localization of their cognate resistance proteins in a process that is essential for resistance protein-mediated plant immunity. Here, we review recent progress in our field on the identification of microbial effectors that are targeted to the nucleus of host plant cells. In addition, we discuss different virulence strategies deployed by microbes, which have been uncovered through examination of the mechanisms that guide nuclear localization of effector proteins. PMID:22639625

Rivas, Susana; Genin, Stéphane

2011-01-01

164

The Exo70 subunit of the exocyst is an effector for both Cdc42 and Rho3 function in polarized exocytosis.  

PubMed

The Rho3 and Cdc42 members of the Rho GTPase family are important regulators of exocytosis in yeast. However, the precise mechanism by which they regulate this process is controversial. Here, we present evidence that the Exo70 component of the exocyst complex is a direct effector of both Rho3 and Cdc42. We identify gain-of-function mutants in EXO70 that potently suppress mutants in RHO3 and CDC42 defective for exocytic function. We show that Exo70 has the biochemical properties expected of a direct effector for both Rho3 and Cdc42. Surprisingly, we find that C-terminal prenylation of these GTPases both promotes the interaction and influences the sites of binding within Exo70. Finally, we demonstrate that the phenotypes associated with novel loss-of-function mutants in EXO70, are entirely consistent with Exo70 as an effector for both Rho3 and Cdc42 function in secretion. These data suggest that interaction with the Exo70 component of the exocyst is a key event in spatial regulation of exocytosis by Rho GTPases. PMID:19955214

Wu, Hao; Turner, Courtney; Gardner, Jimmy; Temple, Brenda; Brennwald, Patrick

2010-02-01

165

Two Fis regulators directly repress the expression of numerous effector-encoding genes in Legionella pneumophila.  

PubMed

Legionella pneumophila is an intracellular human pathogen that utilizes the Icm/Dot type IVB secretion system to translocate a large repertoire of effectors into host cells. For most of these effectors, there is no information regarding their regulation. Therefore, the aim of this study was to examine the involvement of the three L. pneumophila Fis homologs in the regulation of effector-encoding genes. Deletion mutants constructed in the genes encoding the three Fis regulators revealed that Fis1 (lpg0542 gene) and Fis3 (lpg1743) but not Fis2 (lpg1370) are partially required for intracellular growth of L. pneumophila in Acanthamoeba castellanii. To identify pathogenesis-related genes directly regulated by Fis, we established a novel in vivo system which resulted in the discovery of numerous effector-encoding genes directly regulated by Fis. Further examination of these genes revealed that Fis1 and Fis3 repress the level of expression of effector-encoding genes during exponential phase. Three groups of effector-encoding genes were identified: (i) effectors regulated mainly by Fis1, (ii) effectors regulated mainly by Fis3, and (iii) effectors regulated by both Fis1 and Fis3. Examination of the upstream regulatory region of all of these effector-encoding genes revealed multiple putative Fis regulatory elements, and site-directed mutagenesis confirmed that a few of these sites constitute part of a repressor binding element. Furthermore, gel mobility shift assays demonstrated the direct relation between the Fis1 and Fis3 regulators and these regulatory elements. Collectively, our results demonstrate for the first time that two of the three L. pneumophila Fis regulators directly repress the expression of Icm/Dot effector-encoding genes. PMID:25225276

Zusman, Tal; Speiser, Yariv; Segal, Gil

2014-12-01

166

The Salmonella Type III Secretion System Virulence Effector Forms a New Hexameric Chaperone Assembly for Export of Effector/Chaperone Complexes.  

PubMed

Bacteria hijack eukaryotic cells by injecting virulence effectors into host cytosol with a type III secretion system (T3SS). Effectors are targeted with their cognate chaperones to hexameric T3SS ATPase at the bacterial membrane's cytosolic face. In this issue of the Journal of Bacteriology, Roblin et al. (P. Roblin, F. Dewitte, V. Villeret, E. G. Biondi, and C. Bompard, J Bacteriol 197:688-698, 2015, http://dx.doi.org/10.1128/JB.02294-14) show that the T3SS chaperone SigE of Salmonella can form hexameric rings rather than dimers when bound to its cognate effector, SopB, implying a novel multimeric association for chaperone/effector complexes with their ATPase. PMID:25488302

Tsai, Chi-Lin; Burkinshaw, Brianne J; Strynadka, Natalie C J; Tainer, John A

2015-02-15

167

Interleukin-2 Production by Polyfunctional HIV-1-Specific CD8 T-cells is Associated with Enhanced Viral Suppression  

PubMed Central

Background Assays to measure the induction of HIV-1-specific CD8 T-cell responses often rely on measurements of indirect effector function such as chemokine and cytokine production, which may not reflect direct elimination of an invading pathogen. Assessment of the functional ability of CD8 T-cells to suppress HIV-1 replication has been viewed as a surrogate marker of an effectual immune response. To further investigate this, we measured the capacity of virus-specific CD8 T-cells to inhibit HIV-1 replication in an in vitro suppression assay (iVSA). Methods We expanded 15 epitope-specific CD8 T-cell lines from PBMCs of chronically HIV-1 infected progressors (n=5) and controllers (n=4) who were not on antiretroviral therapy. Cell lines were tested for their ability to produce effector molecules (CD107a, IL-2, IFN-?, TNF-?, perforin) and suppress virus replication in autologous CD4 T-cells. Results CD8 T-cell lines from both progressors and controllers had largely similar effector function profiles as determined by intracellular cytokine staining. In contrast, we observed that CD8 T-cell lines derived from controllers show enhanced virus suppression when compared to progressors. Virus suppression was mediated in an MHC-dependent manner and found to correlate with a polyfunctional, IL-2+ CD8 T-cell response. Conclusions Using a sensitive iVSA, we demonstrate that CD8 T-cell mediated suppression of HIV-1 replication is a marker of HIV-1 control. Suppressive capacity was found to correlate with polyfunctional, IL-2 production. Assessment of CD8 T-cell mediated suppression may be an important tool to evaluate vaccine-induced responses. PMID:21637109

Akinsiku, Olusimidele T.; Bansal, Anju; Sabbaj, Steffanie; Heath, Sonya L.; Goepfert, Paul A.

2011-01-01

168

Disentangling charmonium suppression  

NASA Astrophysics Data System (ADS)

Charmonium suppression has been postulated as a unique signature for the creation of hot dense nuclear matter. \\textit{J}/\\psi meson yields, for instance, are predicted to be anomalously suppressed through interactions with the hot and dense medium as well as the disappearance of feed-down channels from more massive charmonium states, when compared to the yields expected from cold nuclear matter (CNM). In both hot and cold nuclear matter the suppression is evaluated by comparing to an expected yield from a participant scaled proton-proton (p+p) baseline. We will discuss the different aspects of \\textit{J}/\\psi suppression and the most recent results from the PHENIX experiment at the RHIC.

Linden Levy, L. A.; PHENIX Collaboration

2009-06-01

169

A genetic screen to isolate type III effectors translocated into pepper cells during  

E-print Network

A genetic screen to isolate type III effectors translocated into pepper cells during Xanthomonas these fusions translocated the AvrBs2 reporter in a TTSS-dependent manner into resistant BS2 pepper cells during repeat and is required for full Xcv pathogenicity in pepper and tomato. The translocated effectors

Mudgettt, Mary Beth

170

How filamentous pathogens co-opt plants; the ins and outs of eukaryotic effectors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Research on effectors secreted by pathogens during host attack has dominated the field of molecular plant-microbe interactions over recent years. Functional analysis of type III secreted effectors that are injected by pathogenic bacteria into host cells has significantly advanced the field and demon...

171

The design of scaled robotic end effectors to mimic razor clam burrowing  

E-print Network

This thesis reviews the design of two scaled mechanical end effectors that mimic the digging of Ensis directus, the Atlantic Razor Clam. Modeled after a 0.5x Ensis scale device, the end effectors are 1.0x and 2.0x Ensis ...

Bollini, Mario Attilio

2009-01-01

172

Calcineurin and Vacuolar-Type H+ATPase Modulate Macrophage Effector Functions  

Microsoft Academic Search

While effector molecules produced by activated macrophages (including nitric oxide, tumor necrosis factor alpha , interleukin 1, etc.) help to eliminate pathogens, high levels of these molecules can be deleterious to the host itself. Despite their importance, the mechanisms modulating macrophage effector functions are poorly understood. This work introduces two key negative regulators that control the levels and duration of

Irina M. Conboy; Devanand Manoli; Vidula Mhaiskar; Patricia P. Jones

1999-01-01

173

Combover/CG10732, a Novel PCP Effector for Drosophila Wing Hair Formation  

E-print Network

and wing hairs in Drosophila melanogaster. Specific PCP effectors in the wing such as Multiple wing hairsCombover/CG10732, a Novel PCP Effector for Drosophila Wing Hair Formation Jeremy K. Fagan1 for Drosophila Wing Hair Formation. PLoS ONE 9(9): e107311. doi:10.1371/journal.pone.0107311 Editor: Esther M

Jenny, Andreas

174

EST Mining and Functional Expression Assays Identify Extracellular Effector Proteins From the Plant Pathogen Phytophthora  

Microsoft Academic Search

Plant pathogenic microbes have the remarkable ability to manipulate biochemical, physiological, and morphological processes in their host plants.These manipulations are ac hieved through a diverse array of effector molecules that can either promote infection or trigger defense responses.We describe a general functional genomics approach aimed at identifying extracellular effector proteins from plant pathogenic microorganisms by combining data mining of expressed

Trudy A. Torto; Shuang Li; Allison Styer; Edgar Huitema; Antonino Testa; Neil A. R. Gow; Pieter van West; Sophien Kamoun

2003-01-01

175

Yeast RNA polymerase III transcription factors and effectors.  

PubMed

Recent data indicate that the well-defined transcription machinery of RNA polymerase III (Pol III) is probably more complex than commonly thought. In this review, we describe the yeast basal transcription factors of Pol III and their involvements in the transcription cycle. We also present a list of proteins detected on genes transcribed by Pol III (class III genes) that might participate in the transcription process. Surprisingly, several of these proteins are involved in RNA polymerase II transcription. Defining the role of these potential new effectors in Pol III transcription in vivo will be the challenge of the next few years. This article is part of a Special Issue entitled: Transcription by Odd Pols. PMID:23063749

Acker, Joël; Conesa, Christine; Lefebvre, Olivier

2013-01-01

176

End effectors and attachments for buried waste excavation equipment  

SciTech Connect

The Buried Waste Integrated Demonstration (BWID) supports the applied research, development, demonstration, and evaluation of a suite of advanced technologies that form a comprehensive remediation system for the effective and efficient remediation of buried waste. Their efforts are identified and coordinated in support of the U.S. Department of Energy (DOE), Environmental Restoration and Waste Management (ER&WM) Department`s needs and objectives. The present focus of BWID is to support retrieval and ex-situ treatment configuration options. Future activities will explore and support containment, and stabilization efforts in addition to the retrieval/ex situ treatment options. This report presents a literature search on the state-of-the-art in end effectors and attachments in support of excavator of buried transuranic waste. Included in the report are excavator platforms and a discussion of the various attachments. Also included is it list of vendors and specifications.

King, R.H.

1993-09-01

177

Differentiation and function of Foxp3(+) effector regulatory T cells.  

PubMed

Regulatory T (Treg) cells are essential for immunological tolerance and homeostasis. Although forkhead box (Fox)p3 is continually required to reinforce the Treg cell program, Treg cells can also undergo stimulus-specific differentiation that is regulated by transcription factors typically associated with the differentiation of conventional CD4(+) T cells. This results in effector Treg (eTreg) cells with unique migratory and functional properties matched to the stimulus that elicited the initial response. Despite this functional and transcriptional heterogeneity, expression of the transcription factor B lymphocyte-induced maturation protein (Blimp)-1, a key player in late B cell and conventional T cell differentiation, is common to all eTreg cells. Here, we discuss the factors that control the differentiation of eTreg cells and their importance in disease settings. PMID:23219401

Cretney, Erika; Kallies, Axel; Nutt, Stephen L

2013-02-01

178

Cell-autonomous effector mechanisms against mycobacterium tuberculosis.  

PubMed

Few pathogens run the gauntlet of sterilizing immunity like Mycobacterium tuberculosis (Mtb). This organism infects mononuclear phagocytes and is also ingested by neutrophils, both of which possess an arsenal of cell-intrinsic effector mechanisms capable of eliminating it. Here Mtb encounters acid, oxidants, nitrosylating agents, and redox congeners, often exuberantly delivered under low oxygen tension. Further pressure is applied by withholding divalent Fe²?, Mn²?, Cu²?, and Zn²?, as well as by metabolic privation in the form of carbon needed for anaplerosis and aromatic amino acids for growth. Finally, host E3 ligases ubiquinate, cationic peptides disrupt, and lysosomal enzymes digest Mtb as part of the autophagic response to this particular pathogen. It is a testament to the evolutionary fitness of Mtb that sterilization is rarely complete, although sufficient to ensure most people infected with this airborne bacterium remain disease-free. PMID:25081628

MacMicking, John D

2014-10-01

179

Cell-Autonomous Effector Mechanisms against Mycobacterium tuberculosis  

PubMed Central

Few pathogens run the gauntlet of sterilizing immunity like Mycobacterium tuberculosis (Mtb). This organism infects mononuclear phagocytes and is also ingested by neutrophils, both of which possess an arsenal of cell-intrinsic effector mechanisms capable of eliminating it. Here Mtb encounters acid, oxidants, nitrosylating agents, and redox congeners, often exuberantly delivered under low oxygen tension. Further pressure is applied by withholding divalent Fe2+, Mn2+, Cu2+, and Zn2+, as well as by metabolic privation in the form of carbon needed for anaplerosis and aromatic amino acids for growth. Finally, host E3 ligases ubiquinate, cationic peptides disrupt, and lysosomal enzymes digest Mtb as part of the autophagic response to this particular pathogen. It is a testament to the evolutionary fitness of Mtb that sterilization is rarely complete, although sufficient to ensure most people infected with this airborne bacterium remain disease-free. PMID:25081628

MacMicking, John D.

2014-01-01

180

Immune Effector Mechanisms Implicated in Atherosclerosis: From Mice to Humans  

PubMed Central

According to the traditional view, atherosclerosis results from a passive buildup of cholesterol in the artery wall. Yet, burgeoning evidence implicates inflammation and immune effector mechanisms in the pathogenesis of this disease. Both innate and adaptive immunity operate during atherogenesis and link many traditional risk factors to altered arterial functions. Inflammatory pathways have become targets in the quest for novel preventive and therapeutic strategies against cardiovascular disease, a growing contributor to morbidity and mortality worldwide. Here we review current experimental and clinical knowledge of the pathogenesis of atherosclerosis through an immunological lens and how host defense mechanisms essential for survival of the species actually contribute to this chronic disease but also present new opportunities for its mitigation. PMID:23809160

Libby, Peter; Lichtman, Andrew H.; Hansson, Göran K.

2013-01-01

181

Modulation of innate immunity by Toxoplasma gondii virulence effectors  

PubMed Central

Preface Toxoplasma gondii is a common parasite of animals and humans that can cause serious opportunistic infections. However, the majority of infections are asymptomatic possibly because the organism has co-evolved with its many vertebrate hosts and has developed multiple strategies to persist asymptomatically for the lifetime of the host. Over the past two decades, infection studies in the mouse, combined with forward genetic approaches aimed at unraveling the molecular basis of infection, have revealed that T. gondii virulence is mediated, in part, by secretion of effector proteins into the host cell during invasion. Here, we review recent advances that illustrate how these virulence factors disarm innate immunity and promote survival of the parasite. PMID:23070557

Hunter, Christopher A.; Sibley, L. David

2013-01-01

182

Origins of ?? T cell effector subsets: a riddle wrapped in an enigma.  

PubMed

?? and ?? T cells are thought to arise from a common precursor in the thymus but play distinct roles in pathogen resistance. Although conventional ?? T cells exit the thymus in a naive state and acquire effector function in the periphery, the effector fate of many ?? T cells is specified in the thymus and exhibits limited plasticity thereafter. This review describes the current models that have been proposed to explain the acquisition of effector fate by ?? T cells, as well as the apparent linkage to V? gene usage. The two predominant models are the predetermination model, which suggests that effector fate is determined prior to TCR expression, perhaps in association with the developmental timing of V? rearrangement, and the TCR-dependence model, which proposes that the nature of the TCR signal, particularly its intensity or duration, plays an important role in influencing effector fate. PMID:25326547

Fahl, Shawn P; Coffey, Francis; Wiest, David L

2014-11-01

183

Independently Evolved Virulence Effectors Converge onto Hubs in a Plant Immune System Network  

PubMed Central

Plants generate effective responses to infection by recognizing both conserved and variable pathogen-encoded molecules. Pathogens deploy virulence effector proteins into host cells, where they interact physically with host proteins to modulate defense. We generated a plant-pathogen immune system protein interaction network using effectors from two pathogens spanning the eukaryote-eubacteria divergence, three classes of Arabidopsis immune system proteins and ~8,000 other Arabidopsis proteins. We noted convergence of effectors onto highly interconnected host proteins, and indirect, rather than direct, connections between effectors and plant immune receptors. We demonstrated plant immune system functions for 15 of 17 tested host proteins that interact with effectors from both pathogens. Thus, pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life cycle strategies. PMID:21798943

Mukhtar, M. Shahid; Carvunis, Anne-Ruxandra; Dreze, Matija; Epple, Petra; Steinbrenner, Jens; Moore, Jonathan; Tasan, Murat; Galli, Mary; Hao, Tong; Nishimura, Marc T.; Pevzner, Samuel J.; Donovan, Susan E.; Ghamsari, Lila; Santhanam, Balaji; Romero, Viviana; Poulin, Matthew M.; Gebreab, Fana; Gutierrez, Bryan J.; Tam, Stanley; Monachello, Dario; Boxem, Mike; Harbort, Christopher J.; McDonald, Nathan; Gai, Lantian; Chen, Huaming; He, Yijian; Vandenhaute, Jean; Roth, Frederick P.; Hill, David E.; Ecker, Joseph R.; Vidal, Marc; Beynon, Jim; Braun, Pascal; Dangl, Jeffery L.

2011-01-01

184

ATP as effector of inorganic pyrophosphatase of Escherichia coli. Identification of the binding site for ATP.  

PubMed

The interaction of Escherichia coli inorganic pyrophosphatase (E-PPase) with effector ATP has been studied. The E-PPase has been chemically modified with the dialdehyde derivative of ATP. It has been established that in the experiment only one molecule of effector ATP is bound to each subunit of the hexameric enzyme. Tryptic digestion of the adenylated protein followed by isolation of a modified peptide by HPLC and its mass-spectrometric identification has showed that it is an amino group of Lys146 that undergoes modification. Molecular docking of ATP to E-PPase indicates that the binding site for effector ATP is located in a cluster of positively charged amino acid residues proposed earlier on the basis of site-directed mutagenesis to participate in binding of effector pyrophosphate. Molecular docking also reveals several other amino acid residues probably involved in the interaction with effectors. PMID:17309442

Rodina, E V; Vorobyeva, N N; Kurilova, S A; Belenikin, M S; Fedorova, N V; Nazarova, T I

2007-01-01

185

Copy number loss or silencing of apoptosis-effector genes in cancer.  

PubMed

Cancer cells undergo a variety of DNA copy number gains and losses (CNV), raising two important questions related to cancer development: (i) Which genes are affected? (ii) And how do CNVs, that do not represent complete deletions but do represent gene-dosage alterations, impact cancer cell functions? Recent studies have indicated that CNVs in cancer can impact genes for regulatory proteins long known to be associated with cancer development, but less is understood about CNVs affecting effector genes. Also, we have recently indicated the likely importance of transcription factor binding site (TFBS) copies in effector genes, in regulating the transition from a proliferative to an apoptotic state. Here we report data-mining analyses that indicate that copies of apoptosis-effector genes are commonly lost in cancer development, in comparison to proliferation-effector genes, and when not, apoptosis effector genes have silenced chromatin structures. PMID:25307873

Mauro, James A; Butler, Shanitra N; Ramsamooj, Michael; Blanck, George

2015-01-01

186

Electroporation of Functional Bacterial Effectors into Mammalian Cells  

PubMed Central

The study of protein interactions in the context of living cells can generate critical information about localization, dynamics, and interacting partners. This information is particularly valuable in the context of host-pathogen interactions. Many pathogen proteins function within host cells in a variety of way such as, enabling evasion of the host immune system and survival within the intracellular environment. To study these pathogen-protein host-cell interactions, several approaches are commonly used, including: in vivo infection with a strain expressing a tagged or mutant protein, or introduction of pathogen genes via transfection or transduction. Each of these approaches has advantages and disadvantages. We sought a means to directly introduce exogenous proteins into cells. Electroporation is commonly used to introduce nucleic acids into cells, but has been more rarely applied to proteins although the biophysical basis is exactly the same. A standard electroporator was used to introduce affinity-tagged bacterial effectors into mammalian cells. Human epithelial and mouse macrophage cells were cultured by traditional methods, detached, and placed in 0.4 cm gap electroporation cuvettes with an exogenous bacterial pathogen protein of interest (e.g. Salmonella Typhimurium GtgE). After electroporation (0.3 kV) and a short (4 hr) recovery period, intracellular protein was verified by fluorescently labeling the protein via its affinity tag and examining spatial and temporal distribution by confocal microscopy. The electroporated protein was also shown to be functional inside the cell and capable of correct subcellular trafficking and protein-protein interaction. While the exogenous proteins tended to accumulate on the surface of the cells, the electroporated samples had large increases in intracellular effector concentration relative to incubation alone. The protocol is simple and fast enough to be done in a parallel fashion, allowing for high-throughput characterization of pathogen proteins in host cells including subcellular targeting and function of virulence proteins. PMID:25650771

Sontag, Ryan L.; Mihai, Cosmin; Orr, Galya; Savchenko, Alexei; Skarina, Tatiana; Cui, Hong; Cort, John R.; Adkins, Joshua N.; Brown, Roslyn N.

2015-01-01

187

Electroporation of functional bacterial effectors into Mammalian cells.  

PubMed

The study of protein interactions in the context of living cells can generate critical information about localization, dynamics, and interacting partners. This information is particularly valuable in the context of host-pathogen interactions. Many pathogen proteins function within host cells in a variety of way such as, enabling evasion of the host immune system and survival within the intracellular environment. To study these pathogen-protein host-cell interactions, several approaches are commonly used, including: in vivo infection with a strain expressing a tagged or mutant protein, or introduction of pathogen genes via transfection or transduction. Each of these approaches has advantages and disadvantages. We sought a means to directly introduce exogenous proteins into cells. Electroporation is commonly used to introduce nucleic acids into cells, but has been more rarely applied to proteins although the biophysical basis is exactly the same. A standard electroporator was used to introduce affinity-tagged bacterial effectors into mammalian cells. Human epithelial and mouse macrophage cells were cultured by traditional methods, detached, and placed in 0.4 cm gap electroporation cuvettes with an exogenous bacterial pathogen protein of interest (e.g. Salmonella Typhimurium GtgE). After electroporation (0.3 kV) and a short (4 hr) recovery period, intracellular protein was verified by fluorescently labeling the protein via its affinity tag and examining spatial and temporal distribution by confocal microscopy. The electroporated protein was also shown to be functional inside the cell and capable of correct subcellular trafficking and protein-protein interaction. While the exogenous proteins tended to accumulate on the surface of the cells, the electroporated samples had large increases in intracellular effector concentration relative to incubation alone. The protocol is simple and fast enough to be done in a parallel fashion, allowing for high-throughput characterization of pathogen proteins in host cells including subcellular targeting and function of virulence proteins. PMID:25650771

Sontag, Ryan L; Mihai, Cosmin; Orr, Galya; Savchenko, Alexei; Skarina, Tatiana; Cui, Hong; Cort, John R; Adkins, Joshua N; Brown, Roslyn N

2015-01-01

188

The novel GrCEP12 peptide from the plant-parasitic nematode Globodera rostochiensis suppresses flg22-mediated PTI  

PubMed Central

The potato cyst nematode Globodera rostochiensis is a biotrophic pathogen that secretes effector proteins into host root cells to promote successful plant parasitism. In addition to the role in generating within root tissue the feeding cells essential for nematode development,1 nematode secreted effectors are becoming recognized as suppressors of plant immunity.2-4 Recently we reported that the effector ubiquitin carboxyl extension protein (GrUBCEP12) from G. rostochiensis is processed into free ubiquitin and a 12-amino acid GrCEP12 peptide in planta. Transgenic potato lines overexpressing the derived GrCEP12 peptide showed increased susceptibility to G. rostochiensis and to an unrelated bacterial pathogen Streptomyces scabies, suggesting that GrCEP12 has a role in suppressing host basal defense or possibly pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) during the parasitic interaction.3 To determine if GrCEP12 functions as a PTI suppressor we evaluated whether GrCEP12 suppresses flg22-induced PTI responses in Nicotiana benthamiana. Interestingly, we found that transient expression of GrCEP12 in N. benthamiana leaves suppressed reactive oxygen species (ROS) production and the induction of two PTI marker genes triggered by the bacterial PAMP flg22, providing direct evidence that GrCEP12 indeed has an activity in PTI suppression. PMID:23803745

Chen, Shiyan; Chronis, Demosthenis; Wang, Xiaohong

2013-01-01

189

Diverse Secreted Effectors Are Required for Salmonella Persistence in a Mouse Infection Model  

SciTech Connect

Salmonella enterica serovar Typhimurium causes typhoid-like disease in mice and is a model of typhoid fever in humans. One of the hallmarks of typhoid is persistence, the ability of the bacteria to survive in the host weeks after infection. Virulence factors called effectors facilitate this process by direct transfer to the cytoplasm of infected cells thereby subverting cellular processes. Secretion of effectors to the cell cytoplasm takes place through multiple routes, including two separate type III secretion (T3SS) apparati as well as outer membrane vesicles. The two T3SS are encoded on separate pathogenicity islands, SPI-1 and -2, with SPI-1 more strongly associated with the intestinal phase of infection, and SPI-2 with the systemic phase. Both T3SS are required for persistence, but the effectors required have not been systematically evaluated. In this study, mutations in 48 described effectors were tested for persistence. We replaced each effector with a specific DNA barcode sequence by allelic exchange and co-infected with a wild-type reference to calculate the ratio of wild-type parent to mutant at different times after infection. The competitive index (CI) was determined by quantitative PCR in which primers that correspond to the barcode were used for amplification. Mutations in all but seven effectors reduced persistence demonstrating that most effectors were required. One exception was CigR, a recently discovered effector that is widely conserved throughout enteric bacteria. Deletion of cigR increased lethality, suggesting that it may be an anti-virulence factor. The fact that almost all Salmonella effectors are required for persistence argues against redundant functions. This is different from effector repertoires in other intracellular pathogens such as Legionella.

Kidwai, Afshan S.; Mushamiri, Ivy T.; Niemann, George; Brown, Roslyn N.; Adkins, Joshua N.; Heffron, Fred

2013-08-12

190

Diverse Secreted Effectors Are Required for Salmonella Persistence in a Mouse Infection Model  

PubMed Central

Salmonella enterica serovar Typhimurium causes typhoid-like disease in mice and is a model of typhoid fever in humans. One of the hallmarks of typhoid is persistence, the ability of the bacteria to survive in the host weeks after infection. Virulence factors called effectors facilitate this process by direct transfer to the cytoplasm of infected cells thereby subverting cellular processes. Secretion of effectors to the cell cytoplasm takes place through multiple routes, including two separate type III secretion (T3SS) apparati as well as outer membrane vesicles. The two T3SS are encoded on separate pathogenicity islands, SPI-1 and -2, with SPI-1 more strongly associated with the intestinal phase of infection, and SPI-2 with the systemic phase. Both T3SS are required for persistence, but the effectors required have not been systematically evaluated. In this study, mutations in 48 described effectors were tested for persistence. We replaced each effector with a specific DNA barcode sequence by allelic exchange and co-infected with a wild-type reference to calculate the ratio of wild-type parent to mutant at different times after infection. The competitive index (CI) was determined by quantitative PCR in which primers that correspond to the barcode were used for amplification. Mutations in all but seven effectors reduced persistence demonstrating that most effectors were required. One exception was CigR, a recently discovered effector that is widely conserved throughout enteric bacteria. Deletion of cigR increased lethality, suggesting that it may be an anti-virulence factor. The fact that almost all Salmonella effectors are required for persistence argues against redundant functions. This is different from effector repertoires in other intracellular pathogens such as Legionella. PMID:23950998

Kidwai, Afshan S.; Mushamiri, Ivy; Niemann, George S.; Brown, Roslyn N.; Adkins, Joshua N.; Heffron, Fred

2013-01-01

191

Plasmodium suppresses expansion of T cell responses to heterologous infections.  

PubMed

Plasmodium remains a major pathogen causing malaria and impairing defense against other infections. Defining how Plasmodium increases susceptibility to heterologous pathogens may lead to interventions that mitigate the severity of coinfections. Previous studies proposed that reduced T cell responses during coinfections are due to diminished recruitment of naive T cells through infection-induced decreases in chemokine CCL21. We found that, although Listeria infections reduced expression of CCL21 in murine spleens, lymphocytic choriomeningitis virus (LCMV)-specific T cell responses were not impaired during Listeria + LCMV coinfection, arguing against a major role for this chemokine in coinfection-induced T cell suppression. In our experiments, Plasmodium yoelii infection led to a reduced CD8(+) T cell response to a subsequent Listeria infection. We propose an alternative mechanism whereby P. yoelii suppresses Listeria-specific T cell responses. We found that Listeria-specific T cells expanded more slowly and resulted in lower numbers in response to coinfection with P. yoelii. Mathematical modeling and experimentation revealed greater apoptosis of Listeria-specific effector T cells as the main mechanism, because P. yoelii infections did not suppress the recruitment or proliferation rates of Listeria-specific T cells. Our results suggest that P. yoelii infections suppress immunity to Listeria by causing increased apoptosis in Listeria-specific T cells, resulting in a slower expansion rate of T cell responses. PMID:25505280

White, Chelsi E; Villarino, Nicolas F; Sloan, Sarah S; Ganusov, Vitaly V; Schmidt, Nathan W

2015-01-15

192

Innate pro–B-cell progenitors protect against type 1 diabetes by regulating autoimmune effector T cells  

PubMed Central

Diverse hematopoietic progenitors, including myeloid populations arising in inflammatory and tumoral conditions and multipotent cells, mobilized by hematopoietic growth factors or emerging during parasitic infections, display tolerogenic properties. Innate immune stimuli confer regulatory functions to various mature B-cell subsets but immature B-cell progenitors endowed with suppressive properties per se or after differentiating into more mature regulatory B cells remain to be characterized. Herein we provide evidence for innate pro-B cells (CpG-proBs) that emerged within the bone marrow both in vitro and in vivo upon Toll-like receptor-9 activation and whose adoptive transfer protected nonobese diabetic mice against type 1 diabetes (T1D). These cells responded to IFN-? released by activated effector T cells (Teffs), by up-regulating their Fas ligand (FasL) expression, which enabled them to kill Teffs through apoptosis. In turn, IFN-? derived from CpG-proBs enhanced IFN-? while dramatically reducing IL-21 production by Teffs. In keeping with the crucial pathogenic role played by IL-21 in T1D, adoptively transferred IFN-?–deficient CpG-proBs did not prevent T1D development. Additionally, CpG-proBs matured in vivo into diverse pancreatic and splenic suppressive FasLhigh B-cell subsets. CpG-proBs may become instrumental in cell therapy of autoimmune diseases either on their own or as graft complement in autologous stem cell transplantation. PMID:23716674

Montandon, Ruddy; Korniotis, Sarantis; Layseca-Espinosa, Esther; Gras, Christophe; Mégret, Jérôme; Ezine, Sophie; Dy, Michel; Zavala, Flora

2013-01-01

193

NleB, a bacterial effector with glycosyltransferase activity targets GADPH function to inhibit NF-?B activation  

PubMed Central

Summary Modulation of NF-?B-dependent responses is critical to the success of attaching/effacing (A/E) human pathogenic E. coli (EPEC and EHEC) and the natural mouse pathogen Citrobacter rodentium. NleB, a highly conserved type III secretion system effector of A/E pathogens, suppresses NF-?B activation, but the underlying mechanisms are unknown. We identified the mammalian glycolysis enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an NleB interacting protein. Further, we discovered that GAPDH interacts with the TNF receptor associated factor 2 (TRAF2), a protein required for TNF-?-mediated NF-?B activation, and regulates TRAF2 polyubiquitination. During infection, NleB functions as a translocated N-acetyl-D-glucosamine (O-GlcNAc) transferase that modifies GAPDH. NleB-mediated GAPDH O-GlcNAcylation disrupts the TRAF2-GAPDH interaction to suppress TRAF2 polyubiquitination and NF-?B activation. Eliminating NleB O-GlcNAcylation activity attenuates C. rodentium colonization of mice. These data identify GAPDH as a TRAF2 signaling cofactor and reveal a virulence strategy employed by A/E pathogens to inhibit NF-?B dependent host innate immune responses. PMID:23332158

Gao, Xiaofei; Wang, Xiaogang; Pham, Thanh H.; Feuerbacher, Leigh Ann; Lubos, Marie-Luise; Huang, Minzhao; Olsen, Rachel; Mushegian, Arcady; Slawson, Chad; Hardwidge, Philip R.

2013-01-01

194

A Rapid One-Generation Genetic Screen in a Drosophila Model to Capture Rhabdomyosarcoma Effectors and Therapeutic Targets.  

PubMed

Rhabdomyosarcoma (RMS) is an aggressive childhood malignancy of neoplastic muscle-lineage precursors that fail to terminally differentiate into syncytial muscle. The most aggressive form of RMS, Alveolar-RMS (A-RMS), is driven by misexpression of the PAX-FOXO1 oncoprotein, which is generated by recurrent chromosomal translocations that fuse either the PAX3 or PAX7 gene to FOXO1. The molecular underpinnings of PAX-FOXO1-mediated RMS pathogenesis remain unclear, however, and clinical outcomes poor. Here, we report a new approach to dissect RMS, exploiting a highly efficient Drosophila PAX7-FOXO1 model uniquely configured to uncover PAX-FOXO1 RMS genetic effectors in only one generation. With this system, we have performed a comprehensive deletion screen against the Drosophila autosomes, and demonstrate that mutation of Mef2, a myogenesis lynchpin in both flies and mammals, dominantly suppresses PAX7-FOXO1 pathogenicity and acts as a PAX7-FOXO1 gene target. Additionally, we reveal that mutation of mastermind, a gene encoding a MEF2 transcriptional co-activator, similarly suppresses PAX7-FOXO1, further pointing towards MEF2 transcriptional activity as a PAX-FOXO1 underpinning. These studies show the utility of the PAX-FOXO1 Drosophila system as a robust one-generation (F1) RMS gene discovery platform and demonstrate how Drosophila transgenic conditional expression models can be configured for the rapid dissection of human disease. PMID:25491943

Galindo, Kathleen A; Endicott, Tiana R; Avirneni-Vadlamudi, Usha; Galindo, Rene L

2014-12-01

195

A Rapid One-Generation Genetic Screen in a Drosophila Model to Capture Rhabdomyosarcoma Effectors and Therapeutic Targets  

PubMed Central

Rhabdomyosarcoma (RMS) is an aggressive childhood malignancy of neoplastic muscle-lineage precursors that fail to terminally differentiate into syncytial muscle. The most aggressive form of RMS, alveolar-RMS, is driven by misexpression of the PAX-FOXO1 oncoprotein, which is generated by recurrent chromosomal translocations that fuse either the PAX3 or PAX7 gene to FOXO1. The molecular underpinnings of PAX-FOXO1?mediated RMS pathogenesis remain unclear, however, and clinical outcomes poor. Here, we report a new approach to dissect RMS, exploiting a highly efficient Drosophila PAX7-FOXO1 model uniquely configured to uncover PAX-FOXO1 RMS genetic effectors in only one generation. With this system, we have performed a comprehensive deletion screen against the Drosophila autosomes and demonstrate that mutation of Mef2, a myogenesis lynchpin in both flies and mammals, dominantly suppresses PAX7-FOXO1 pathogenicity and acts as a PAX7-FOXO1 gene target. Additionally, we reveal that mutation of mastermind, a gene encoding a MEF2 transcriptional coactivator, similarly suppresses PAX7-FOXO1, further pointing toward MEF2 transcriptional activity as a PAX-FOXO1 underpinning. These studies show the utility of the PAX-FOXO1 Drosophila system as a robust one-generation (F1) RMS gene discovery platform and demonstrate how Drosophila transgenic conditional expression models can be configured for the rapid dissection of human disease. PMID:25491943

Galindo, Kathleen A.; Endicott, Tiana R.; Avirneni-Vadlamudi, Usha; Galindo, Rene L.

2014-01-01

196

Design schemes and comparison research of the end-effector of large space manipulator  

NASA Astrophysics Data System (ADS)

The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit. Currently, there are few researches about the end-effector, and the existing end-effectors have some disadvantages, such as poor misalignment tolerance capability and complex mechanical components. According to the end positioning errors and the residual vibration characters of the large space manipulators, two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed. And the end-effector should accommodate the following misalignments of the mechanical interface. The translation misalignments in axial and radial directions and the angular misalignments in roll, pitch and yaw are ±100 mm, 100 mm, ±10o, ±15o, ±15o, respectively. Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily. The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes, and they are designed in detail. The capabilities of misalignment tolerance and soft capture are validated and evaluated, through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software. The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement. And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll, pitch and yaw of the steel cable-snared end-effector are 30mm, 15mm, 6o, 3o and 3o larger than those of the three fingers-three petals end-effector, respectively. And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector. The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.

Feng, Fei; Liu, Yiwei; Liu, Hong; Cai, Hegao

2012-07-01

197

?? T Cells Acquire Effector Fates in the Thymus and Differentiate into Cytokine-Producing Effectors in a Listeria Model of Infection Independently of CD28 Costimulation  

PubMed Central

Both antigen recognition and CD28 costimulation are required for the activation of naïve ?? T cells and their subsequent differentiation into cytokine-producing or cytotoxic effectors. Notably, this two-signal paradigm holds true for all ?? T cell subsets, regardless of whether they acquire their effector function in the periphery or the thymus. Because of contradictory results, however, it remains unresolved as to whether CD28 costimulation is necessary for ?? T cell activation and differentiation. Given that ?? T cells have been recently shown to acquire their effector fates in the thymus, it is conceivable that the contradictory results may be explained, in part, by a differential requirement for CD28 costimulation in the development or differentiation of each ?? T cell effector subset. To test this, we examined the role of CD28 in ?? T cell effector fate determination and function. We report that, although IFN?-producing ?? T (??-IFN?) cells express higher levels of CD28 than IL-17-producing ?? T (??-17) cells, CD28-deficiency had no effect on the thymic development of either subset. Also, following Listeria infection, we found that the expansion and differentiation of ??-17 and ??-IFN? effectors were comparable between CD28+/+ and CD28?/? mice. To understand why CD28 costimulation is dispensable for ?? T cell activation and differentiation, we assessed glucose uptake and utilization by ?? T cells, as CD28 costimulation is known to promote glycolysis in ?? T cells. Importantly, we found that ?? T cells express higher surface levels of glucose transporters than ?? T cells and, when activated, exhibit effector functions over a broader range of glucose concentrations than activated ?? T cells. Together, these data not only demonstrate an enhanced glucose metabolism in ?? T cells but also provide an explanation for why ?? T cells are less dependent on CD28 costimulation than ?? T cells. PMID:23671671

Laird, Renee M.; Wolf, Benjamin J.

2013-01-01

198

Explosion suppression system  

DOEpatents

An explosion suppression system and triggering apparatus therefor are provided for quenching gas and dust explosions. An electrically actuated suppression mechanism which dispenses an extinguishing agent into the path ahead of the propagating flame is actuated by a triggering device which is light powered. This triggering device is located upstream of the propagating flame and converts light from the flame to an electrical actuation signal. A pressure arming device electrically connects the triggering device to the suppression device only when the explosion is sensed by a further characteristic thereof beside the flame such as the pioneer pressure wave. The light powered triggering device includes a solar panel which is disposed in the path of the explosion and oriented between horizontally downward and vertical. Testing mechanisms are also preferably provided to test the operation of the solar panel and detonator as well as the pressure arming mechanism.

Sapko, Michael J. (Finleyville, PA); Cortese, Robert A. (Pittsburgh, PA)

1992-01-01

199

The effector T cell response to ryegrass pollen is counterregulated by simultaneous induction of regulatory T cells.  

PubMed

Allergy is associated with pathological Th2 responses to otherwise harmless environmental Ags. In contrast, nonallergic individuals mount nonpathological immune responses to allergens, partly attributed to regulatory T cell (Treg) activity. Although thymus-derived natural Tregs have been shown to maintain tolerance to self-Ags and prevent autoimmunity, the generation of Tregs specific to non-self-Ags is less well understood. We investigated the potential for induction of Tregs from PBMCs of ryegrass pollen-allergic or healthy subjects by stimulation in vitro with ryegrass pollen extract in the absence of additional exogenous stimuli. We found that two subsets of proliferating CD4(+) T cells were induced, one expressing intermediate levels of Foxp3 (and IFN-gamma, IL-4, IL-17, or IL-2) and the other expressing high levels of Foxp3 (and no effector cytokines). After enrichment based on CD39 expression, the Foxp3(hi) subset suppressed CD4(+) T cell proliferation and IFN-gamma production. The Foxp3(hi) Treg originated from both conversion of dividing non-Tregs (CD4(+)CD25(-)CD127(hi)) and expansion of natural Tregs (CD4(+)CD25(+)CD127(lo)). Stable functional Tregs expressing high levels of Foxp3 were induced simultaneously with effector T cells by allergen stimulation. Induction of Foxp3(hi) Tregs was reduced in allergic subjects. These results indicate that the cogeneration of Foxp3(hi) Tregs in response to allergen may be a mechanism for controlling allergic reactions in healthy individuals, which is impaired in those with allergies. PMID:20308632

Mittag, Diana; Scholzen, Anja; Varese, Nirupama; Baxter, Lorraine; Paukovics, Geza; Harrison, Leonard C; Rolland, Jennifer M; O'Hehir, Robyn E

2010-05-01

200

HPat a Decapping Activator Interacting with the miRNA Effector Complex  

PubMed Central

Animal miRNAs commonly mediate mRNA degradation and/or translational repression by binding to their target mRNAs. Key factors for miRNA-mediated mRNA degradation are the components of the miRNA effector complex (AGO1 and GW182) and the general mRNA degradation machinery (deadenylation and decapping enzymes). The CCR4-NOT1 complex required for the deadenylation of target mRNAs is directly recruited to the miRNA effector complex. However, it is unclear whether the following decapping step is only a consequence of deadenylation occurring independent of the miRNA effector complex or e.g. decapping activators can get recruited to the miRNA effector complex. In this study we performed split-affinity purifications in Drosophila cells and provide evidence for the interaction of the decapping activator HPat with the miRNA effector complex. Furthermore, in knockdown analysis of various mRNA degradation factors we demonstrate the importance of NOT1 for this interaction. This suggests that deadenylation and/or the recruitment of NOT1 protein precedes the association of HPat with the miRNA effector complex. Since HPat couples deadenylation and decapping, the recruitment of HPat to the miRNA effector complex provides a mechanism to commit the mRNA target for degradation. PMID:23977167

Bariši?-Jäger, Elisabeth; Kr?cioch, Izabela; Hosiner, Stefanie; Antic, Sanja; Dorner, Silke

2013-01-01

201

Space-based multifunctional end effector systems functional requirements and proposed designs  

NASA Technical Reports Server (NTRS)

The end effector is an essential element of teleoperator and telerobot systems to be employed in space in the next decade. The report defines functional requirements for end effector systems to perform operations that are currently only feasible through Extra-Vehicular Activity (EVA). Specific tasks and functions that the end effectors must be capable of performing are delineated. Required capabilities for forces and torques, clearances, compliance, and sensing are described, using current EVA requirements as guidelines where feasible. The implications of these functional requirements on the elements of potential end effector systems are discussed. The systems issues that must be considered in the design of space-based manipulator systems are identified; including impacts on subsystems tightly coupled to the end effector, i.e., control station, information processing, manipulator arm, tool and equipment stowage. Possible end effector designs are divided into three categories: single degree-of-freedom end effectors, multiple degree of freedom end effectors, and anthropomorphic hands. Specific design alternatives are suggested and analyzed within the individual categories. Two evaluations are performed: the first considers how well the individual end effectors could substitute for EVA; the second compares how manipulator systems composed of the top performers from the first evaluation would improve the space shuttle Remote Manipulator System (RMS) capabilities. The analysis concludes that the anthropomorphic hand is best-suited for EVA tasks. A left- and right-handed anthropomorphic manipulator arm configuration is suggested as appropriate to be affixed to the RMS, but could also be used as part of the Smart Front End for the Orbital Maneuvering Vehicle (OMV). The technical feasibility of the anthropomorphic hand and its control are demonstrated. An evolutionary development approach is proposed and approximate scheduling provided for implementing the suggested manipulator systems in time for space stations operations in the early 1990s.

Mishkin, A. H.; Jau, B. M.

1988-01-01

202

Divergent Antibody Subclass and Specificity Profiles but Not Protective HLA-B Alleles Are Associated with Variable Antibody Effector Function among HIV-1 Controllers  

PubMed Central

ABSTRACT Understanding the coordination between humoral and cellular immune responses may be the key to developing protective vaccines, and because genetic studies of long-term HIV-1 nonprogressors have associated specific HLA-B alleles with spontaneous control of viral replication, this subject group presents an opportunity to investigate relationships between arms of the adaptive immune system. Given evidence suggesting that cellular immunity may play a role in viral suppression, we sought to determine whether and how the humoral immune response might vary among controllers. Significantly, Fc-mediated antibody effector functions have likewise been associated with durable viral control. In this study, we compared the effector function and biophysical features of HIV-specific antibodies in a cohort of controllers with and without protective HLA-B alleles in order to investigate whether there was evidence for multiple paths to HIV-1 control, or whether cellular and humoral arms of immunity might exhibit coordinated profiles. However, with the exception of IgG2 antibodies to gp41, HLA status was not associated with divergent humoral responses. This finding did not result from uniform antibody responses across subjects, as controllers could be regrouped according to strong differences in their HIV-specific antibody subclass specificity profiles. These divergent antibody profiles were further associated with significant differences in nonneutralizing antibody effector function, with levels of HIV-specific IgG1 acting as the major distinguishing factor. Thus, while HLA background among controllers was associated with minimal differences in humoral function, antibody subclass and specificity profiles were associated with divergent effector function, suggesting that these features could be used to make functional predictions. Because these nonneutralizing antibody activities have been associated with spontaneous viral control, reduced viral load, and nonprogression in infected subjects and protection in vaccinated subjects, understanding the specific features of IgGs with potentiated effector function may be critical to vaccine and therapeutic antibody development. IMPORTANCE In this study, we investigated whether the humoral and cellular arms of adaptive immunity exhibit coordinated or compensatory activity by studying the antibody response among HIV-1 controllers with different genetic backgrounds. PMID:24352471

Lai, Jennifer I.; Licht, Anna F.; Dugast, Anne-Sophie; Suscovich, Todd; Choi, Ickwon; Bailey-Kellogg, Chris; Alter, Galit

2014-01-01

203

Using the Kinect to limit abnormal kinematics and compensation strategies during therapy with end effector robots.  

PubMed

Abnormal kinematics and the use of compensation strategies during training limit functional improvement from therapy. The Kinect is a low cost ($100) sensor that does not require any markers to be placed on the user. Integration of this sensor into currently used therapy systems can provide feedback about the user's movement quality, and the use of compensatory strategies to complete tasks. This paper presents a novel technique of adding the Kinect to an end effector robot to limit compensation strategies and to train normal joint coordination during movements with an end effector robot. This methodology has wider implications for other robotic and passively actuated end effector rehabilitation devices. PMID:24187203

Brokaw, Elizabeth B; Lum, Peter S; Cooper, Rory A; Brewer, Bambi R

2013-06-01

204

TALEs from a Spring – Superelasticity of Tal Effector Protein Structures  

PubMed Central

Transcription activator-like effectors (TALEs) are DNA-related proteins that recognise and bind specific target sequences to manipulate gene expression. Recently determined crystal structures show that their common architecture reveals a superhelical overall structure that may undergo drastic conformational changes. To establish a link between structure and dynamics in TALE proteins we have employed coarse-grained elastic-network modelling of currently available structural data and implemented a force-probe setup that allowed us to investigate their mechanical behaviour in computer experiments. Based on the measured force-extension curves we conclude that TALEs exhibit superelastic dynamical properties allowing for large-scale global conformational changes along their helical axis, which represents the soft direction in such proteins. For moderate external forcing the TALE models behave like linear springs, obeying Hooke's law, and the investigated structures can be characterised and compared by a corresponding spring constant. We show that conformational flexibility underlying the large-scale motions is not homogeneously distributed over the TALE structure, but instead soft spot residues around which strain is accumulated and which turn out to represent key agents in the transmission of conformational motions are identified. They correspond to the RVD loop residues that have been experimentally determined to play an eminent role in the binding process of target DNA. PMID:25313859

Flechsig, Holger

2014-01-01

205

Tissue-specific effector functions of innate lymphoid cells  

PubMed Central

Innate lymphoid cells (ILCs) is the collective term for a group of related innate lymphocytes, including natural killer (NK) cells and the more recently discovered non-NK ILCs, which all lack rearranged antigen receptors such as those expressed by T and B cells. Similar to NK cells, the newly discovered ILCs depend on the transcription factor Id2 and the common ?-chain of the interleukin-2 receptor for development. However, in contrast to NK cells, non-NK ILCs also require interleukin-7. In addition to the cytotoxic functions of NK cells, assuring protection against tumour development and viruses, new data indicate that ILCs contribute to a wide range of homeostatic and pathophysiological conditions in various organs via specialized cytokine production capabilities. Here we summarize current knowledge on ILCs with a particular emphasis on their tissue-specific effector functions, in the gut, liver, lungs and uterus. When possible, we try to highlight the role that these cells play in humans. PMID:23489335

Björkström, Niklas K; Kekäläinen, Eliisa; Mjösberg, Jenny

2013-01-01

206

No death without life: vital functions of apoptotic effectors  

PubMed Central

As a result of the genetic experiments performed in Caenorhabditis elegans, it has been tacitly assumed that the core proteins of the ‘apoptotic machinery’ (CED-3, -4, -9 and EGL-1) would be solely involved in cell death regulation/execution and would not exert any functions outside of the cell death realm. However, multiple studies indicate that the mammalian orthologs of these C. elegans proteins (i.e. caspases, Apaf-1 and multidomain proteins of the Bcl-2 family) participate in cell death-unrelated processes. Similarly, loss-of-function mutations of ced-4 compromise the mitotic arrest of DNA-damaged germline cells from adult nematodes, even in a context in which the apoptotic machinery is inoperative (for instance due to mutations of egl-1 or ced-3). Moreover, EGL-1 is required for the activation of autophagy in starved nematodes. Finally, the depletion of caspase-independent death effectors, such as apoptosis-inducing factor (AIF) and endonuclease G, provokes cell death-independent consequences, both in mammals and in yeast (Saccharomyces cerevisiae). These results corroborate the conjecture that any kind of protein that has previously been specifically implicated in apoptosis might have a phylogenetically conserved apoptosis-unrelated function, most likely as part of an adaptive response to cellular stress. PMID:18309324

Galluzzi, L; Joza, N; Tasdemir, E; Maiuri, MC; Hengartner, M; Abrams, JM; Tavernarakis, N; Penninger, J; Madeo, F; Kroemer, G

2010-01-01

207

Plasma Aerodynamic Control Effectors for Improved Wind Turbine Performance  

SciTech Connect

Orbital Research Inc is developing an innovative Plasma Aerodynamic Control Effectors (PACE) technology for improved performance of wind turbines. The PACE system is aimed towards the design of "smart" rotor blades to enhance energy capture and reduce aerodynamic loading and noise using flow-control. The PACE system will provide ability to change aerodynamic loads and pitch distribution across the wind turbine blade without any moving surfaces. Additional benefits of the PACE system include reduced blade structure weight and complexity that should translate into a substantially reduced initial cost. During the Phase I program, the ORI-UND Team demonstrated (proof-of-concept) performance improvements on select rotor blade designs using PACE concepts. Control of both 2-D and 3-D flows were demonstrated. An analytical study was conducted to estimate control requirements for the PACE system to maintain control during wind gusts. Finally, independent laboratory experiments were conducted to identify promising dielectric materials for the plasma actuator, and to examine environmental effects (water and dust) on the plasma actuator operation. The proposed PACE system will be capable of capturing additional energy, and reducing aerodynamic loading and noise on wind turbines. Supplementary benefits from the PACE system include reduced blade structure weight and complexity that translates into reduced initial capital costs.

Mehul P. Patel; Srikanth Vasudevan; Robert C. Nelson; Thomas C. Corke

2008-08-01

208

Epigenetic regulation of NK cell differentiation and effector functions  

PubMed Central

Upon maturation, natural killer (NK) cells acquire effector functions and regulatory receptors. New insights suggest a considerable functional heterogeneity and dynamic regulation of receptor expression in mature human NK cell subsets based on different developmental axes. Such processes include acquisition of lytic granules as well as regulation of cytokine production in response to exogenous cytokine stimulation or target cell interactions. One axis is regulated by expression of inhibitory receptors for self-MHC class I molecules, whereas other axes are less well defined but likely are driven by different activating receptor engagements or cytokines. Moreover, the recent identification of long-lived NK cell subsets in mice that are able to expand and respond rapidly following a secondary viral challenge suggest previously unappreciated plasticity in the programming of NK cell differentiation. Here, we review advances in our understanding of mature NK cell development and plasticity with regards to regulation of cellular function. Furthermore, we highlight some of the major questions that remain pertaining to the epigenetic changes that underlie the differentiation and functional specialization of NK cells and the regulation of their responses. PMID:23450696

Cichocki, Frank; Miller, Jeffrey S.; Anderson, Stephen K.; Bryceson, Yenan T.

2013-01-01

209

TAL effectors--pathogen strategies and plant resistance engineering.  

PubMed

Transcription activator-like effectors (TALEs) from plant pathogenic Xanthomonas spp. and the related RipTALs from Ralstonia solanacearum are DNA-binding proteins with a modular DNA-binding domain. This domain is both predictable and programmable, which simplifies elucidation of TALE function in planta and facilitates generation of DNA-binding modules with desired specificity for biotechnological approaches. Recently identified TALE host target genes that either promote or stop bacterial disease provide new insights into how expression of TALE genes affects the plant–pathogen interaction. Since its elucidation the TALE code has been continuously refined and now provides a mature tool that, in combination with transcriptome profiling, allows rapid isolation of novel TALE target genes. The TALE code is also the basis for synthetic promoter-traps that mediate recognition of TALE or RipTAL proteins in engineered plants. In this review, we will summarize recent findings in plant-focused TALE research. In addition, we will provide an outline of the newly established gene isolation approach for TALE or RipTAL host target genes with an emphasis on potential pitfalls. PMID:25539004

Boch, Jens; Bonas, Ulla; Lahaye, Thomas

2014-12-01

210

Targeted Mutagenesis of Arabidopsis thaliana Using Engineered TAL Effector Nucleases  

PubMed Central

Custom TAL effector nucleases (TALENs) are increasingly used as reagents to manipulate genomes in vivo. Here, we used TALENs to modify the genome of the model plant, Arabidopsis thaliana. We engineered seven TALENs targeting five Arabidopsis genes, namely ADH1, TT4, MAPKKK1, DSK2B, and NATA2. In pooled seedlings expressing the TALENs, we observed somatic mutagenesis frequencies ranging from 2–15% at the intended targets for all seven TALENs. Somatic mutagenesis frequencies as high as 41–73% were observed in individual transgenic plant lines expressing the TALENs. Additionally, a TALEN pair targeting a tandemly duplicated gene induced a 4.4-kb deletion in somatic cells. For the most active TALEN pairs, namely those targeting ADH1 and NATA2, we found that TALEN-induced mutations were transmitted to the next generation at frequencies of 1.5–12%. Our work demonstrates that TALENs are useful reagents for achieving targeted mutagenesis in this important plant model. PMID:23979944

Christian, Michelle; Qi, Yiping; Zhang, Yong; Voytas, Daniel F.

2013-01-01

211

Evaluation of Nod-Like Receptor (NLR) Effector Domain Interactions  

PubMed Central

Members of the Nod-like receptor (NLR) family recognize intracellular pathogens and recruit a variety of effector molecules, including pro-caspases and kinases, which in turn are implicated in cytokine processing and NF-?B activation. In order to elucidate the intricate network of NLR signaling, which is still fragmentary in molecular terms, we applied comprehensive yeast two-hybrid analysis for unbiased evaluation of physical interactions between NLRs and their adaptors (ASC, CARD8) as well as kinase RIPK2 and inflammatory caspases (C1, C2, C4, C5) under identical conditions. Our results confirmed the interaction of NOD1 and NOD2 with RIPK2, and between NLRP3 and ASC, but most importantly, our studies revealed hitherto unrecognized interactions of NOD2 with members of the NLRP subfamily. We found that NOD2 specifically and directly interacts with NLRP1, NLRP3 and NLRP12. Furthermore, we observed homodimerization of the RIPK2 CARD domains and identified residues in NOD2 critical for interaction with RIPK2. In conclusion, our work provides further evidence for the complex network of protein-protein interactions underlying NLR function. PMID:19337385

Kufer, Thomas A.; Schwarzenbacher, Robert

2009-01-01

212

A Plant Defense Response Effector Induces Microbial Apoptosis  

Microsoft Academic Search

Osmotin is a tobacco PR-5 protein that has antifungal activity and is implicated in host-plant defense. We show here that osmotin induces apoptosis in Saccharomyces cerevisiae. Induction of apoptosis was correlated with intracellular accumulation of reactive oxygen species and was mediated by RAS2, but not RAS1. Osmotin treatment resulted in suppression of transcription of stress-responsive genes via the RAS2\\/cAMP pathway.

Meena L Narasimhan; Barbara Damsz; Maria A Coca; José I Ibeas; Dae-Jin Yun; José M Pardo; Paul M Hasegawa; Ray A Bressan

2001-01-01

213

Human Effector / Initiator Gene Sets That Regulate Myometrial Contractility During Term and Preterm Labor  

PubMed Central

Objective Distinct processes govern transition from quiescence to activation during term (TL) and preterm labor (PTL). We sought gene sets responsible for TL and PTL, along with the effector genes necessary for labor independent of gestation and underlying trigger. Methods Expression was analyzed in term and preterm +/? labor (n =6 subjects/group). Gene sets were generated using logic operations. Results 34 genes were similarly expressed in PTL/TL but absent from nonlabor samples (Effector Set). 49 genes were specific to PTL (Preterm Initiator Set) and 174 to TL (Term Initiator Set). The gene ontogeny processes comprising Term Initiator and Effector Sets were diverse, though inflammation was represented in 4 of the top 10; inflammation dominated the Preterm Initiator Set. Comments TL and PTL differ dramatically in initiator profiles. Though inflammation is part of the Term Initiator and the Effector Sets, it is an overwhelming part of PTL associated with intraamniotic inflammation. PMID:20452493

WEINER, Carl P.; MASON, Clifford W.; DONG, Yafeng; BUHIMSCHI, Irina A.; SWAAN, Peter W.; BUHIMSCHI, Catalin S.

2010-01-01

214

Intrathymic programming of effector fates in three molecularly distinct ?? T cell subtypes  

E-print Network

Innate ?? T cells function in the early phase of immune responses. Although innate ?? T cells have often been studied as one homogenous population, they can be functionally classified into effector subsets on the basis of ...

Narayan, Kavitha

215

Structures of PI4KIII? complexes show simultaneous recruitment of Rab11 and its effectors  

PubMed Central

Phosphatidylinositol 4-kinases (PI4Ks) and small guanosine triphosphatases (GTPases) are essential for processes that require expansion and remodeling of phosphatidylinositol 4-phosphate (PI4P)-containing membranes, including cytokinesis, intracellular development of malarial pathogens, and replication of a wide range of RNA viruses. However, the structural basis for coordination of PI4K, GTPases and their effectors is unknown. Here, we describe structures of PI4KB (PI4KIII?) bound to the small GTPase Rab11a without and with the Rab11 effector protein FIP3. The Rab11-PI4KIII? interface is unique compared with known structures of Rab complexes, and does not involve switch regions used by GTPase effectors. Our data provide a mechanism for how PI4KIII? coordinates Rab11 and its effectors on PI4P-enriched membranes, and also provide strategies for the design of specific inhibitors that could potentially target plasmodial PI4KIII? to combat malaria. PMID:24876499

Burke, John E.; Inglis, Alison J.; Perisic, Olga; Masson, Glenn R.; McLaughlin, Stephen H.; Rutaganira, Florentine; Shokat, Kevan M.; Williams, Roger L.

2014-01-01

216

Plant parasitic nematode effectors target host defense and nuclear functions to establish feeding cells  

PubMed Central

Plant parasitic nematodes are microscopic worms, the most damaging species of which have adopted a sedentary lifestyle within their hosts. These obligate endoparasites have a biotrophic relationship with plants, in which they induce the differentiation of root cells into hypertrophied, multinucleate feeding cells (FCs). Effectors synthesized in the esophageal glands of the nematode are injected into the plant cells via the syringe-like stylet and play a key role in manipulating the host machinery. The establishment of specialized FCs requires these effectors to modulate many aspects of plant cell morphogenesis and physiology, including defense responses. This cell reprogramming requires changes to host nuclear processes. Some proteins encoded by parasitism genes target host nuclei. Several of these proteins were immunolocalized within FC nuclei or shown to interact with host nuclear proteins. Comparative genomics and functional analyses are gradually revealing the roles of nematode effectors. We describe here these effectors and their hypothesized roles in the unique feeding behavior of these pests. PMID:23493679

Quentin, Michaëel; Abad, Pierre; Favery, Bruno

2013-01-01

217

Autophagy is essential for effector CD8(+) T cell survival and memory formation.  

PubMed

The importance of autophagy in the generation of memory CD8(+) T cells in vivo is not well defined. We report here that autophagy was dynamically regulated in virus-specific CD8(+) T cells during acute infection of mice with lymphocytic choriomeningitis virus. In contrast to the current paradigm, autophagy decreased in activated proliferating effector CD8(+) T cells and was then upregulated when the cells stopped dividing just before the contraction phase. Consistent with those findings, deletion of the gene encoding either of the autophagy-related molecules Atg5 or Atg7 had little to no effect on the proliferation and function of effector cells, but these autophagy-deficient effector cells had survival defects that resulted in compromised formation of memory T cells. Our studies define when autophagy is needed during effector and memory differentiation and warrant reexamination of the relationship between T cell activation and autophagy. PMID:25362489

Xu, Xiaojin; Araki, Koichi; Li, Shuzhao; Han, Jin-Hwan; Ye, Lilin; Tan, Wendy G; Konieczny, Bogumila T; Bruinsma, Monique W; Martinez, Jennifer; Pearce, Erika L; Green, Douglas R; Jones, Dean P; Virgin, Herbert W; Ahmed, Rafi

2014-12-01

218

Balancing Selection at a Frog Antimicrobial Peptide Locus: Fluctuating Immune Effector Alleles?  

E-print Network

Balancing Selection at a Frog Antimicrobial Peptide Locus: Fluctuating Immune Effector Alleles such as antimicrobial peptides (AMPs). We describe genetic diversity at a brevinin-1 AMP locus in three species

Blouin, Michael S.

219

Structural Insights into the Effector - Immunity System Tae4/Tai4 from Salmonella typhimurium.  

PubMed

Type-6-secretion systems of Gram-negative bacteria are widely distributed needle-like multi-protein complexes that are involved in microbial defense mechanisms. During bacterial competition these injection needles dispense effector proteins into the periplasm of competing bacteria where they induce degradation of the peptidoglycan scaffold and lead to cell lysis. Donor cells co-produce immunity proteins and shuttle them into their own periplasm to prevent accidental toxication by siblings. Recently, a plethora of previously unidentified hydrolases have been suggested to be peptidoglycan degrading amidases. These hydrolases are part of effector/immunity pairs that have been associated with bacterial warfare by type-6-secretion systems. The Tae4 and Tai4 operon encoded by Salmonella typhimurium is one of these newly discovered effector/immunity pairs. The Tae4 effector proteins induce cell lysis by cleaving the ?-D-glutamyl-L-meso-diaminopimelic acid amide bond of acceptor stem muropeptides of the Gram-negative peptidoglycan. Although homologues of the Tae4/Tai4 system have been identified in various different pathogens, little is known about the functional mechanism of effector protein activity and their inhibition by the cognate immunity proteins. Here, we present the high-resolution crystal structure of the effector Tae4 of S. typhimurium in complex with its immunity protein Tai4. We show that Tae4 contains a classical NlpC/P60-peptidase core which is common to other effector proteins of the type-6-secretion system. However, Tae4 has unique structural features that are exclusively conserved within the family of Tae4 effectors and which are important for the substrate specificity. Most importantly, we show that although the overall structure of Tai4 is different to previously described immunity proteins, the essential mode of enzyme inhibition is conserved. Additionally, we provide evidence that inhibition in the Tae4/Tai4 heterotetramer relies on a central Tai4 dimer in order to acquire functionality. PMID:23826277

Benz, Juliane; Reinstein, Jochen; Meinhart, Anton

2013-01-01

220

Structural Insights into the Effector – Immunity System Tae4/Tai4 from Salmonella typhimurium  

PubMed Central

Type-6-secretion systems of Gram-negative bacteria are widely distributed needle-like multi-protein complexes that are involved in microbial defense mechanisms. During bacterial competition these injection needles dispense effector proteins into the periplasm of competing bacteria where they induce degradation of the peptidoglycan scaffold and lead to cell lysis. Donor cells co-produce immunity proteins and shuttle them into their own periplasm to prevent accidental toxication by siblings. Recently, a plethora of previously unidentified hydrolases have been suggested to be peptidoglycan degrading amidases. These hydrolases are part of effector/immunity pairs that have been associated with bacterial warfare by type-6-secretion systems. The Tae4 and Tai4 operon encoded by Salmonella typhimurium is one of these newly discovered effector/immunity pairs. The Tae4 effector proteins induce cell lysis by cleaving the ?-D-glutamyl-L-meso-diaminopimelic acid amide bond of acceptor stem muropeptides of the Gram-negative peptidoglycan. Although homologues of the Tae4/Tai4 system have been identified in various different pathogens, little is known about the functional mechanism of effector protein activity and their inhibition by the cognate immunity proteins. Here, we present the high-resolution crystal structure of the effector Tae4 of S. typhimurium in complex with its immunity protein Tai4. We show that Tae4 contains a classical NlpC/P60-peptidase core which is common to other effector proteins of the type-6-secretion system. However, Tae4 has unique structural features that are exclusively conserved within the family of Tae4 effectors and which are important for the substrate specificity. Most importantly, we show that although the overall structure of Tai4 is different to previously described immunity proteins, the essential mode of enzyme inhibition is conserved. Additionally, we provide evidence that inhibition in the Tae4/Tai4 heterotetramer relies on a central Tai4 dimer in order to acquire functionality. PMID:23826277

Benz, Juliane; Reinstein, Jochen; Meinhart, Anton

2013-01-01

221

Regulatory T cells in ? irradiation-induced immune suppression.  

PubMed

Sublethal total body ? irradiation (TBI) of mammals causes generalized immunosuppression, in part by induction of lymphocyte apoptosis. Here, we provide evidence that a part of this immune suppression may be attributable to dysfunction of immune regulation. We investigated the effects of sublethal TBI on T cell memory responses to gain insight into the potential for loss of vaccine immunity following such exposure. We show that in mice primed to an MHC class I alloantigen, the accelerated graft rejection T memory response is specifically lost several weeks following TBI, whereas identically treated naïve mice at the same time point had completely recovered normal rejection kinetics. Depletion in vivo with anti-CD4 or anti-CD25 showed that the mechanism involved cells consistent with a regulatory T cell (T reg) phenotype. The loss of the T memory response following TBI was associated with a relative increase of CD4+CD25+ Foxp3+ expressing T regs, as compared to the CD8+ T effector cells requisite for skin graft rejection. The radiation-induced T memory suppression was shown to be antigen-specific in that a third party ipsilateral graft rejected with normal kinetics. Remarkably, following the eventual rejection of the first MHC class I disparate skin graft, the suppressive environment was maintained, with markedly prolonged survival of a second identical allograft. These findings have potential importance as regards the immunologic status of T memory responses in victims of ionizing radiation exposure and apoptosis-inducing therapies. PMID:22723935

McFarland, Hugh I; Puig, Montserrat; Grajkowska, Lucja T; Tsuji, Kazuhide; Lee, Jay P; Mason, Karen P; Verthelyi, Daniela; Rosenberg, Amy S

2012-01-01

222

Event-Related Alpha Suppression in Response to Facial Motion  

PubMed Central

While biological motion refers to both face and body movements, little is known about the visual perception of facial motion. We therefore examined alpha wave suppression as a reduction in power is thought to reflect visual activity, in addition to attentional reorienting and memory processes. Nineteen neurologically healthy adults were tested on their ability to discriminate between successive facial motion captures. These animations exhibited both rigid and non-rigid facial motion, as well as speech expressions. The structural and surface appearance of these facial animations did not differ, thus participants decisions were based solely on differences in facial movements. Upright, orientation-inverted and luminance-inverted facial stimuli were compared. At occipital and parieto-occipital regions, upright facial motion evoked a transient increase in alpha which was then followed by a significant reduction. This finding is discussed in terms of neural efficiency, gating mechanisms and neural synchronization. Moreover, there was no difference in the amount of alpha suppression evoked by each facial stimulus at occipital regions, suggesting early visual processing remains unaffected by manipulation paradigms. However, upright facial motion evoked greater suppression at parieto-occipital sites, and did so in the shortest latency. Increased activity within this region may reflect higher attentional reorienting to natural facial motion but also involvement of areas associated with the visual control of body effectors. PMID:24586735

Girges, Christine; Wright, Michael J.; Spencer, Janine V.; O’Brien, Justin M. D.

2014-01-01

223

In-flight adaptive performance optimization (APO) control using redundant control effectors of an aircraft  

NASA Technical Reports Server (NTRS)

Practical application of real-time (or near real-time) Adaptive Performance Optimization (APO) is provided for a transport aircraft in steady climb, cruise, turn descent or other flight conditions based on measurements and calculations of incremental drag from a forced response maneuver of one or more redundant control effectors defined as those in excess of the minimum set of control effectors required to maintain the steady flight condition in progress. The method comprises the steps of applying excitation in a raised-cosine form over an interval of from 100 to 500 sec. at the rate of 1 to 10 sets/sec of excitation, and data for analysis is gathered in sets of measurements made during the excitation to calculate lift and drag coefficients C.sub.L and C.sub.D from two equations, one for each coefficient. A third equation is an expansion of C.sub.D as a function of parasitic drag, induced drag, Mach and altitude drag effects, and control effector drag, and assumes a quadratic variation of drag with positions .delta..sub.i of redundant control effectors i=1 to n. The third equation is then solved for .delta..sub.iopt the optimal position of redundant control effector i, which is then used to set the control effector i for optimum performance during the remainder of said steady flight or until monitored flight conditions change by some predetermined amount as determined automatically or a predetermined minimum flight time has elapsed.

Gilyard, Glenn B. (Inventor)

1999-01-01

224

Proteogenomic analysis of the Venturia pirina (Pear Scab Fungus) secretome reveals potential effectors.  

PubMed

A proteogenomic analysis is presented for Venturia pirina, a fungus that causes scab disease on European pear (Pyrus communis). V. pirina is host-specific, and the infection is thought to be mediated by secreted effector proteins. Currently, only 36 V. pirina proteins are catalogued in GenBank, and the genome sequence is not publicly available. To identify putative effectors, V. pirina was grown in vitro on and in cellophane sheets mimicking its growth in infected leaves. Secreted extracts were analyzed by tandem mass spectrometry, and the data (ProteomeXchange identifier PXD000710) was queried against a protein database generated by combining in silico predicted transcripts with six frame translations of a whole genome sequence of V. pirina (GenBank Accession JEMP00000000 ). We identified 1088 distinct V. pirina protein groups (FDR 1%) including 1085 detected for the first time. Thirty novel (not in silico predicted) proteins were found, of which 14 were identified as potential effectors based on characteristic features of fungal effector protein sequences. We also used evidence from semitryptic peptides at the protein N-terminus to corroborate in silico signal peptide predictions for 22 proteins, including several potential effectors. The analysis highlights the utility of proteogenomics in the study of secreted effectors. PMID:24965097

Cooke, Ira R; Jones, Dan; Bowen, Joanna K; Deng, Cecilia; Faou, Pierre; Hall, Nathan E; Jayachandran, Vignesh; Liem, Michael; Taranto, Adam P; Plummer, Kim M; Mathivanan, Suresh

2014-08-01

225

Evolution of RXLR-Class Effectors in the Oomycete Plant Pathogen Phytophthora ramorum  

PubMed Central

Phytophthora plant pathogens contain many hundreds of effectors potentially involved in infection of host plants. Comparative genomic analyses have shown that these effectors evolve rapidly and have been subject to recent expansions. We examined the recent sequence evolution of RXLR-class effector gene families in the sudden oak death pathogen, P. ramorum. We found that P. ramorum RXLR effectors have taken multiple evolutionary paths, including loss or gain of repeated domains, recombination or gene conversion among paralogs, and selection on point mutations. Sequencing of homologs from two subfamilies in P. ramorum’s closest known relatives revealed repeated gene duplication and divergence since speciation with P. lateralis. One family showed strong signatures of recombination while the other family has evolved primarily by point mutation. Comparison of a small number of the hundreds of RXLR-class effectors across three clonal lineages of P. ramorum shows striking divergence in alleles among lineages, suggesting the potential for functional differences between lineages. Our results suggest future avenues for examination of rapidly evolving effectors in P. ramorum, including investigation of the functional and coevolutionary significance of the patterns of sequence evolution that we observed. PMID:24244484

Goss, Erica M.; Press, Caroline M.; Grünwald, Niklaus J.

2013-01-01

226

A salmonella type three secretion effector/chaperone complex adopts a hexameric ring-like structure.  

PubMed

Many bacterial pathogens use type three secretion systems (T3SS) to inject virulence factors, named effectors, directly into the cytoplasm of target eukaryotic cells. Most of the T3SS components are conserved among plant and animal pathogens, suggesting a common mechanism of recognition and secretion of effectors. However, no common motif has yet been identified for effectors allowing T3SS recognition. In this work, we performed a biochemical and structural characterization of the Salmonella SopB/SigE chaperone/effector complex by small-angle X-ray scattering (SAXS). Our results showed that the SopB/SigE complex is assembled in dynamic homohexameric-ring-shaped structures with an internal tunnel. In this ring, the chaperone maintains a disordered N-terminal end of SopB molecules, in a good position to be reached and processed by the T3SS. This ring dimensionally fits the ring-organized molecules of the injectisome, including ATPase hexameric rings; this organization suggests that this structural feature is important for ATPase recognition by T3SS. Our work constitutes the first evidence of the oligomerization of an effector, analogous to the organization of the secretion machinery, obtained in solution. As effectors share neither sequence nor structural identity, the quaternary oligomeric structure could constitute a strategy evolved to promote the specificity and efficiency of T3SS recognition. PMID:25404693

Roblin, Pierre; Dewitte, Frédérique; Villeret, Vincent; Biondi, Emanuele G; Bompard, Coralie

2015-02-15

227

New clues in the nucleus: transcriptional reprogramming in effector-triggered immunity  

PubMed Central

The robustness of plant effector-triggered immunity is correlated with massive alterations of the host transcriptome. Yet the molecular mechanisms that cause and underlie this reprogramming remain obscure. Here we will review recent advances in deciphering nuclear functions of plant immune receptors and of associated proteins. Important open questions remain, such as the identities of the primary transcription factors involved in control of effector-triggered immune responses, and indeed whether this can be generalized or whether particular effector-resistance protein interactions impinge on distinct sectors in the transcriptional response web. Multiple lines of evidence have implicated WRKY transcription factors at the core of responses to microbe-associated molecular patterns and in intersections with effector-triggered immunity. Recent findings from yeast two-hybrid studies suggest that members of the TCP transcription factor family are targets of several effectors from diverse pathogens. Additional transcription factor families that are directly or indirectly involved in effector-triggered immunity are likely to be identified. PMID:24062762

Bhattacharjee, Saikat; Garner, Christopher M.; Gassmann, Walter

2013-01-01

228

Early effector T cells producing significant IFN-gamma develop into memory.  

PubMed

Currently, transition of T cells from effector to memory is believed to occur as a consequence of exposure to residual suboptimal Ag found in lymphoid tissues at the waning end of the effector phase and microbial clearance. This led to the interpretation that memory arises from slightly activated late effectors producing reduced amounts of IFN-gamma. In this study, we show that CD4 T cells from the early stage of the effector phase in which both the Ag and activation are optimal also transit to memory. Moreover, early effector T cells that have undergone four divisions expressed significant IL-7R, produced IFN-gamma, and yielded rapid and robust memory responses. Cells that divided three times that had marginal IL-7R expression and no IFN-gamma raised base level homeostatic memory, whereas those that have undergone only two divisions and produced IFN-gamma yielded conditioned memory despite low IL-7R expression. Thus, highly activated early effectors generated under short exposure to optimal Ag in vivo develop into memory, and such transition is dependent on a significant production of the cell's signature cytokine, IFN-gamma. PMID:18097018

Bell, J Jeremiah; Ellis, Jason S; Guloglu, F Betul; Tartar, Danielle M; Lee, Hyun-Hee; Divekar, Rohit D; Jain, Renu; Yu, Ping; Hoeman, Christine M; Zaghouani, Habib

2008-01-01

229

Pressure suppression containment system  

DOEpatents

A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of-coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto. 6 figures.

Gluntz, D.M.; Townsend, H.E.

1994-03-15

230

Pattern-triggered immunity suppresses programmed cell death triggered by fumonisin b1.  

PubMed

Programmed cell death (PCD) is a crucial process for plant innate immunity and development. In plant innate immunity, PCD is believed to prevent the spread of pathogens from the infection site. Although proper control of PCD is important for plant fitness, we have limited understanding of the molecular mechanisms regulating plant PCD. Plant innate immunity triggered by recognition of effectors (effector-triggered immunity, ETI) is often associated with PCD. However pattern-triggered immunity (PTI), which is triggered by recognition of elicitors called microbe-associated molecular patterns (MAMPs), is not. Therefore we hypothesized that PTI might suppress PCD. Here we report that PCD triggered by the mycotoxin fumonisin B1 (FB1) can be suppressed by PTI in Arabidopsis. FB1-triggered cell death was suppressed by treatment with the MAMPs flg22 (a part of bacterial flagellin) or elf18 (a part of the bacterial elongation factor EF-Tu) but not chitin (a component of fungal cell walls). Although plant hormone signaling is associated with PCD and PTI, both FB1-triggered cell death and suppression of cell death by flg22 treatment were still observed in mutants deficient in jasmonic acid (JA), ethylene (ET) and salicylic acid (SA) signaling. The MAP kinases MPK3 and MPK6 are transiently activated and inactivated within one hour during PTI. We found that FB1 activated MPK3 and MPK6 about 36-48 hours after treatment. Interestingly, this late activation was attenuated by flg22 treatment. These results suggest that PTI suppression of FB1-triggered cell death may involve suppression of MPK3/MPK6 signaling but does not require JA/ET/SA signaling. PMID:23560104

Igarashi, Daisuke; Bethke, Gerit; Xu, Yuan; Tsuda, Kenichi; Glazebrook, Jane; Katagiri, Fumiaki

2013-01-01

231

Pattern-Triggered Immunity Suppresses Programmed Cell Death Triggered by Fumonisin B1  

PubMed Central

Programmed cell death (PCD) is a crucial process for plant innate immunity and development. In plant innate immunity, PCD is believed to prevent the spread of pathogens from the infection site. Although proper control of PCD is important for plant fitness, we have limited understanding of the molecular mechanisms regulating plant PCD. Plant innate immunity triggered by recognition of effectors (effector-triggered immunity, ETI) is often associated with PCD. However pattern-triggered immunity (PTI), which is triggered by recognition of elicitors called microbe-associated molecular patterns (MAMPs), is not. Therefore we hypothesized that PTI might suppress PCD. Here we report that PCD triggered by the mycotoxin fumonisin B1 (FB1) can be suppressed by PTI in Arabidopsis. FB1-triggered cell death was suppressed by treatment with the MAMPs flg22 (a part of bacterial flagellin) or elf18 (a part of the bacterial elongation factor EF-Tu) but not chitin (a component of fungal cell walls). Although plant hormone signaling is associated with PCD and PTI, both FB1-triggered cell death and suppression of cell death by flg22 treatment were still observed in mutants deficient in jasmonic acid (JA), ethylene (ET) and salicylic acid (SA) signaling. The MAP kinases MPK3 and MPK6 are transiently activated and inactivated within one hour during PTI. We found that FB1 activated MPK3 and MPK6 about 36–48 hours after treatment. Interestingly, this late activation was attenuated by flg22 treatment. These results suggest that PTI suppression of FB1-triggered cell death may involve suppression of MPK3/MPK6 signaling but does not require JA/ET/SA signaling. PMID:23560104

Igarashi, Daisuke; Bethke, Gerit; Xu, Yuan; Tsuda, Kenichi; Glazebrook, Jane; Katagiri, Fumiaki

2013-01-01

232

Tremor suppression in ECG  

PubMed Central

Background Electrocardiogram recordings are very often contaminated by high-frequency noise usually power-line interference and EMG disturbances (tremor). Specific method for interference cancellation without affecting the proper ECG components, called subtraction procedure, was developed some two decades ago. Filtering out the tremor remains a priori partially successful since it has a relatively wide spectrum, which overlaps the useful ECG frequency band. Method The proposed method for tremor suppression implements the following three procedures. Contaminated ECG signals are subjected to moving averaging (comb filter with linear phase characteristic) with first zero set at 50 Hz to suppress tremor and PL interference simultaneously. The reduced peaks of QRS complexes and other relatively high and steep ECG waves are then restored by an introduced by us procedure called linearly-angular, so that the useful high frequency components are preserved in the range specified by the embedded in the ECG instrument filter, usually up to 125 Hz. Finally, a Savitzky-Golay smoothing filter is applied for supplementary tremor suppression outside the QRS complexes. Results The results obtained show a low level of the residual EMG disturbances together with negligible distortion of the wave shapes regardless of rhythm and morphology changes. PMID:19019218

Dotsinsky, Ivan A; Mihov, Georgy S

2008-01-01

233

Menstrual suppression: current perspectives  

PubMed Central

Menstrual suppression to provide relief of menstrual-related symptoms or to manage medical conditions associated with menstrual morbidity or menstrual exacerbation has been used clinically since the development of steroid hormonal therapies. Options range from the extended or continuous use of combined hormonal oral contraceptives, to the use of combined hormonal patches and rings, progestins given in a variety of formulations from intramuscular injection to oral therapies to intrauterine devices, and other agents such as gonadotropin-releasing hormone (GnRH) antagonists. The agents used for menstrual suppression have variable rates of success in inducing amenorrhea, but typically have increasing rates of amenorrhea over time. Therapy may be limited by side effects, most commonly irregular, unscheduled bleeding. These therapies can benefit women’s quality of life, and by stabilizing the hormonal milieu, potentially improve the course of underlying medical conditions such as diabetes or a seizure disorder. This review addresses situations in which menstrual suppression may be of benefit, and lists options which have been successful in inducing medical amenorrhea. PMID:25018654

Hillard, Paula Adams

2014-01-01

234

Design of endoscopic micro-robotic end effectors: safety and performance evaluation based on physical intestinal tissue damage characteristics.  

PubMed

During the last several years, legged locomotive mechanism has been considered as one of the main self-propelling mechanisms for future endoscopic microrobots due to its superior propulsion efficiency of an endoscopic microrobot inside the intestinal track. Nevertheless, its clinical application has been largely limited since the legged locomotive mechanism utilizes an end effector which has a sharp tip to generate sufficient traction by physically penetrating and interlocking with the intestinal tissue. This can cause excessive physical tissue damage or even complete perforation of the intestinal wall that can lead to abdominal inflammation. Hence, in this work two types of new end effectors, penetration-limited end effector (PLEE) and bi-material structured end effector (BMEE) were specially designed to acquire high medical safety as well as effective traction generation performance. The microscopic end effector specimens were fabricated with micro-wire electric discharge machining process. Traction generation performance of the end effectors was evaluated by direct measurement of resistance forces during contact-sliding tests using a custom-built contact-sliding tester. The safety of the end effector design was evaluated by examination of microscopic intestinal tissue damage using a scanning electron microscope (SEM). Physical damage characteristics of the intestinal tissue and related contact physics of the end effectors were discussed. From the results, the end effectors were evaluated with respect to their prospects in future medical applications as safe end effectors as well as micro-surgical tools. PMID:24634056

Kim, Young-Tae; Kim, Dae-Eun; Yang, Sungwook; Yoon, Eui-Sung

2014-06-01

235

Non-replicating adenovirus vectors expressing avian influenza virus hemagglutinin and nucleocapsid proteins induce chicken specific effector, memory and effector memory CD8+ T lymphocytes  

PubMed Central

Avian influenza virus (AIV) specific CD8+ T lymphocyte responses stimulated by intramuscular administration of an adenovirus (Ad) vector expressing either HA or NP were evaluated in chickens following ex vivo stimulation by non-professional antigen presenting cells. The CD8+ T lymphocyte responses were AIV specific, MHC-I restricted, and cross-reacted with heterologousH7N2 AIV strain. Specific effector responses, at 10 days post-inoculation (p.i.), were undetectable at 2 weeks p.i., and memory responses were detected from 3 to 8 weeks p.i. Effector memory responses, detected 1 week following a booster inoculation, were significantly greater than the primary responses and, within 7 days, declined to undetectable levels. Inoculation of an Ad-vector expressing human NP resulted in significantly greater MHC restricted, activation of CD8+ T cell responses specific for AIV. Decreases in all responses with time were most dramatic with maximum activation of T cells as observed following effector and effector memory responses. PMID:20557918

Singh, Shailbala; Toro, Haroldo; Tang, De-Chu; Briles, Worthie E.; Yates, Linda M.; Kopulos, Renee T.; Collisson, Ellen W.

2010-01-01

236

CCR2-Dependent Dendritic Cell Accumulation in the Central Nervous System during Early Effector Experimental Autoimmune Encephalomyelitis Is Essential for Effector T Cell Restimulation In Situ and Disease Progression.  

PubMed

Dendritic cells (DCs)-although absent from the healthy CNS parenchyma-rapidly accumulate within brain and spinal cord tissue during neuroinflammation associated with experimental autoimmune encephalomyelitis (EAE; a mouse model of multiple sclerosis). Yet, although DCs have been appreciated for their role in initiating adaptive immune responses in peripheral lymphoid organ tissues, how DCs infiltrate the CNS and contribute to ongoing neuroinflammation in situ is poorly understood. In this study, we report the following: 1) CD11c(+) bone marrow-derived DCs and CNS-infiltrating DCs express chemokine receptor CCR2; 2) compared with CCR2(+/+) cells, adoptively transferred CCR2(-/-) bone marrow-derived DCs or DC precursors do not accumulate in the CNS during EAE, despite abundance in blood; 3) CCR2(-/-) DCs show less accumulation in the inflamed CNS in mixed bone marrow chimeras, when compared with CCR2(+/+) DCs; and 4) ablation of CCR2(+/+) DCs during EAE clinical onset delays progression and attenuates cytokine production by infiltrating T cells. Whereas the role of CCR2 in monocyte migration into the CNS has been implicated previously, the role of CCR2 in DC infiltration into the CNS has never been directly addressed. Our data suggest that CCR2-dependent DC recruitment to the CNS during ongoing neuroinflammation plays a crucial role in effector T cell cytokine production and disease progression, and signify that CNS-DCs and circulating DC precursors might be key therapeutic targets for suppressing ongoing neuroinflammation in CNS autoimmune diseases. PMID:25505278

Clarkson, Benjamin D; Walker, Alec; Harris, Melissa G; Rayasam, Aditya; Sandor, Matyas; Fabry, Zsuzsanna

2015-01-15

237

Glioma-Derived ADAM10 Induces Regulatory B Cells to Suppress CD8+ T Cells  

PubMed Central

CD8+ T cells play an important role in the anti-tumor activities of the body. The dysfunction of CD8+ T cells in glioma is unclear. This study aims to elucidate the glioma cell-derived ADAM10 (A Disintegrin and metalloproteinase domain-containing protein 10) in the suppression of CD8+ effector T cells by the induction of regulatory B cells. In this study, glioma cells were isolated from surgically removed glioma tissue and stimulated by Phorbol myristate acetage (PMA) in the culture. The levels of ADAM10 in the culture were determined by enzyme-linked immunosorbent assay. Immune cells were assessed by flow cytometry. The results showed that the isolated glioma cells express ADAM10, which was markedly up regulated after stimulated with PMA. The glioma-derived ADAM10 induced activated B cells to differentiate into regulatory B cells, the later suppressed CD8+ T cell proliferation as well as the induced regulatory T cells, which also showed the immune suppressor effect on CD8+ effector T cell proliferation. In conclusion, glioma cells produce ADAM10 to induce Bregs; the latter suppresses CD8+ T cells and induces Tregs. PMID:25127032

Li, Wen-sheng; Luo, Lun; Huang, Zhen-chao; Guo, Ying

2014-01-01

238

PD-1/PD-L1 Blockade Together With Vaccine Therapy Facilitates Effector T-Cell Infiltration Into Pancreatic Tumors.  

PubMed

Pancreatic ductal adenocarcinoma (PDA) has a poor prognosis due to late detection and resistance to conventional therapies. Published studies show that the PDA tumor microenvironment is predominantly infiltrated with immune suppressive cells and signals that if altered, would allow effective immunotherapy. However, single-agent checkpoint inhibitors including agents that alter immune suppressive signals in other human cancers such as cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed death 1 (PD-1), and its ligand PD-L1, have failed to demonstrate objective responses when given as single agents to PDA patients. We recently reported that inhibition of the CTLA-4 pathway when given together with a T cell inducing vaccine gives objective responses in metastatic PDA patients. In this study, we evaluated blockade of the PD-1/PD-L1 pathway. We found that PD-L1 is weakly expressed at a low frequency in untreated human and murine PDAs but treatment with a granulocyte macrophage colony-stimulating factor secreting PDA vaccine (GVAX) significantly upregulates PD-L1 membranous expression after treatment of tumor-bearing mice. In addition, combination therapy with vaccine and PD-1 antibody blockade improved murine survival compared with PD-1 antibody monotherapy or GVAX therapy alone. Furthermore, PD-1 blockade increased effector CD8 T lymphocytes and tumor-specific interferon-? production of CD8 T cells in the tumor microenvironment. Immunosuppressive pathways, including regulatory T cells and CTLA-4 expression on T cells were overcome by the addition of vaccine and low-dose cyclophosphamide to PD-1 blockade. Collectively, our study supports combining PD-1 or PD-L1 antibody therapy with a T cell inducing agent for PDA treatment. PMID:25415283

Soares, Kevin C; Rucki, Agnieszka A; Wu, Annie A; Olino, Kelly; Xiao, Qian; Chai, Yi; Wamwea, Anthony; Bigelow, Elaine; Lutz, Eric; Liu, Linda; Yao, Sheng; Anders, Robert A; Laheru, Daniel; Wolfgang, Christopher L; Edil, Barish H; Schulick, Richard D; Jaffee, Elizabeth M; Zheng, Lei

2015-01-01

239

Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus  

PubMed Central

Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25+/highCD127Ø/lowFoxP3+, and effector T cells were defined as CD25+CD127+FoxP3Ø. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4+TREG and CD28+TREG cells and an increased frequency of CD40L+TREG cells. There was a decrease in the TREG/effector-T ratio for GITR+, HLA-DR+, OX40+, and CD45RO+ cells, and an increased ratio of TREG/effector-T CD40L+ cells in patients with SLE. In addition, CD40L+TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease. PMID:25098715

Mesquita Júnior, D.; Cruvinel, W.M.; Araujo, J.A.P.; Salmazi, K.C.; Kallas, E.G.; Andrade, L.E.C.

2014-01-01

240

'All things considered': transcriptional regulation of T helper type 2 cell differentiation from precursor to effector activation.  

PubMed

T helper type 2 (Th2) cells are critical to host defence against helminth infection and the pathogenesis of allergic diseases. The differentiation of Th2 cells from naive CD4 T cells is controlled by intricate transcriptional mechanisms. At the precursor stage of naive CD4 T cells, transcriptional mechanisms maintain the potential and in the meantime prevent spontaneous differentiation to Th2 fate. In addition, intrachromosomal interactions important for co-ordinated expression of Th2 cytokines pre-exist in naive CD4 T cells. Upon T-cell receptor (TCR) engagement, naive CD4 T cells are induced by polarizing signals of the interleukin-4/Stat6 and Jagged/Notch pathways to up-regulate the expression of GATA-3. Once up-regulated, GATA-3 drives Th2 and suppresses Th1 differentiation in a cell autonomous fashion. In this stage of differentiation, the Th2 cytokine locus, as well as the interferon-? locus, undergoes chromatin remodelling and epigenetic modifications that contribute to the somatic memory of Th2 cytokine gene expression pattern. Once differentiated, Th2 effector cells promptly produce Th2 cytokines upon TCR stimulation, which is regulated by concerted actions of GATA-3, TCR signalling, enhancers and the Th2 locus control region. This review provides a detailed account of the transcriptional regulatory events at these different stages of Th2 differentiation. PMID:23668241

Zeng, Wei-ping

2013-09-01

241

Halofuginone-induced amino acid starvation regulates Stat3-dependent Th17 effector function and reduces established autoimmune inflammation.  

PubMed

The IL-23 pathway is genetically linked to autoimmune disease in humans and is required for pathogenic Th17 cell function in mice. However, because IL-23R-expressing mature Th17 cells are rare and poorly defined in mice at steady-state, little is known about IL-23 signaling. In this study, we show that the endogenous CCR6(+) memory T cell compartment present in peripheral lymphoid organs of unmanipulated mice expresses Il23r ex vivo, displays marked proinflammatory responses to IL-23 stimulation in vitro, and is capable of transferring experimental autoimmune encephalomyelitis. The prolyl-tRNA synthetase inhibitor halofuginone blocks IL-23-induced Stat3 phosphorylation and IL-23-dependent proinflammatory cytokine expression in endogenous CCR6(+) Th17 cells via activation of the amino acid starvation response (AAR) pathway. In vivo, halofuginone shows therapeutic efficacy in experimental autoimmune encephalomyelitis, reducing both established disease progression and local Th17 cell effector function within the CNS. Mechanistically, AAR activation impairs Stat3 responses downstream of multiple cytokine receptors via selective, posttranscriptional suppression of Stat3 protein levels. Thus, our study reveals latent pathogenic functions of endogenous Th17 cells that are regulated by both IL-23 and AAR pathways and identifies a novel regulatory pathway targeting Stat3 that may underlie selective immune regulation by the AAR. PMID:24489094

Carlson, Thaddeus J; Pellerin, Alex; Djuretic, Ivana M; Trivigno, Catherine; Koralov, Sergei B; Rao, Anjana; Sundrud, Mark S

2014-03-01

242

Sequential Induction of Effector Function, Tissue Migration and Cell Death during Polyclonal Activation of Mouse Regulatory T-Cells  

PubMed Central

The ability of CD4+Foxp3+ regulatory T-cells (Treg) to produce interleukin (IL)-10 is important for the limitation of inflammation at environmental interfaces like colon or lung. Under steady state conditions, however, few Tregs produce IL-10 ex vivo. To investigate the origin and fate of IL-10 producing Tregs we used a superagonistic mouse anti-mouse CD28 mAb (CD28SA) for polyclonal in vivo stimulation of Tregs, which not only led to their numeric expansion but also to a dramatic increase in IL-10 production. IL-10 secreting Tregs strongly upregulated surface receptors associated with suppressive function as compared to non-producing Tregs. Furthermore, polyclonally expanding Tregs shifted their migration receptor pattern after activation from a CCR7+CCR5? lymph node-seeking to a CCR7?CCR5+ inflammation-seeking phenotype, explaining the preferential recruitment of IL-10 producers to sites of ongoing immune responses. Finally, we observed that IL-10 producing Tregs from CD28SA stimulated mice were more apoptosis-prone in vitro than their IL-10 negative counterparts. These findings support a model where prolonged activation of Tregs results in terminal differentiation towards an IL-10 producing effector phenotype associated with a limited lifespan, implicating built-in termination of immunosuppression. PMID:23226238

Langenhorst, Daniela; Gogishvili, Tea; Ribechini, Eliana; Kneitz, Susanne; McPherson, Kirsty; Lutz, Manfred B.; Hünig, Thomas

2012-01-01

243

A Mec17-Myosin II Effector Axis Coordinates Microtubule Acetylation and Actin Dynamics to Control Primary Cilium Biogenesis  

PubMed Central

Primary cilia are specialized, acetylated microtubule-based signaling processes. Cilium assembly is activated by cellular quiescence and requires reconfiguration of microtubules, the actin cytoskeleton, and vesicular trafficking machinery. How these components are coordinated to activate ciliogenesis remains unknown. Here we identify the microtubule acetyltransferase Mec-17 and myosin II motors as the key effectors in primary cilium biogenesis. We found that myosin IIB (Myh10) is required for cilium formation; however, myosin IIA (Myh9) suppresses it. Myh10 binds and antagonizes Myh9 to increase actin dynamics, which facilitates the assembly of the pericentrosomal preciliary complex (PPC) that supplies materials for cilium growth. Importantly, Myh10 expression is upregulated by serum-starvation and this induction requires Mec-17, which is itself accumulated upon cellular quiescence. Pharmacological stimulation of microtubule acetylation also induces Myh10 expression and cilium formation. Thus cellular quiescence induces Mec17 to couple the production of acetylated microtubules and Myh10, whose accumulation overcomes the inhibitory role of Myh9 and initiates ciliogenesis. PMID:25494100

Rao, Yanhua; Hao, Rui; Wang, Bin; Yao, Tso-Pang

2014-01-01

244

Identification of the protein sequence of the type III effector XopD from the B100 strain of Xanthomonas campestris pv campestris  

PubMed Central

During evolution, pathogens have developed sophisticated strategies to suppress plant defense responses and promote successful colonization of their hosts. In their attempt to quell host resistance, Gram-negative phytopathogenic bacteria inject type III effectors (T3Es) into plant cells, where they typically target plant components essential for the establishment of defense responses. We have recently shown that the XopD T3E from the strain B100 of Xanthomonas campestris pathovar campestris (XopDXccB100) is able to target AtMYB30, a positive regulator of Arabidopsis defense responses. This protein interaction leads to inhibition of AtMYB30 transcriptional activity and promotion of bacterial virulence. Here, we describe the identification of the complete protein sequence of XopDXccB100, which presents an N-terminal extension of 40 amino acids with respect to the protein annotated in public databases. The implications of this finding are discussed. PMID:22353870

Canonne, Joanne; Pichereaux, Carole; Marino, Daniel; Roby, Dominique; Rossignol, Michel; Rivas, Susana

2012-01-01

245

B effector cells activated by a chimeric protein consisting of IL-2 and the ectodomain of TGF-? receptor II induce potent antitumor immunity.  

PubMed

We have previously shown that interleukin (IL)-2 receptor-expressing lymphoid cells stimulated with a chimeric protein linking IL-2 to the ectodomain of TGF-? receptor II (also known as FIST) become resistant to TGF-?-mediated suppression and produce significant amounts of proinflammatory cytokines. In this study, we have characterized the antigen presentation properties of FIST-stimulated B cells (hereafter inducible B effector cells, iBEC). FIST converts naïve splenic B cells to B effector cells characterized by potent antigen presentation properties and production of TNF? and IFN?. iBECs display hyperphosphorylation of STAT3 and STAT5 downstream of the IL-2 receptor and upregulation of T-bet expression. iBECs maintain B-cell identity based on the expression of PAX5 and CD19 and overexpress Smad7, which confers resistance to TGF-?-mediated suppression of B-cell activation. iBEC antitumor immunity was determined by a mouse model of lymphoma-expressing ovalbumin (E.G7-OVA) as a specific tumor antigen. OVA-pulsed iBECs function as antigen-presenting cells (APC) in vitro by inducing the activation of OVA-specific CD4(+) and CD8(+) T cells, respectively, and in vivo by conferring complete protective immunity against E.G7-OVA tumor challenge. In addition, OVA-pulsed iBECs promote tumor regression in immunocompetent C57Bl/6 mice bearing E.G7-OVA tumors. In conclusion, iBECs represent an entirely novel B cell-derived APC for immune therapy of cancer. PMID:22241086

Penafuerte, Claudia; Ng, Spencer; Bautista-Lopez, Norma; Birman, Elena; Forner, Kathy; Galipeau, Jacques

2012-03-01

246

Trajectory planning and control of a Stewart platform-based end-effector with passive compliance for part assembly  

Microsoft Academic Search

This paper presents the kinematic analysis and trajectory planning for a six-degrees-of-freedom end-effector whose design is based on the Stewart platform mechanism. The end-effector is composed of two platforms and six linear actuators driven by stepper motors. A spring-loaded platform is used to provide passive compliance to the end-effector during a part assembly. A closed-form solution is derived for the

Charles C. Nguyen; S. S. Antrazi; J.-Y. Park; Zhen-lei Zhou

1992-01-01

247

Unihemispheric Burst Suppression  

PubMed Central

Burst suppression (BS) consists of bursts of high-voltage slow and sharp wave activity alternating with periods of background suppression in the electroencephalogram (EEG). When induced by deep anesthesia or encephalopathy, BS is bihemispheric and is often viewed as a non-epileptic phenomenon. In contrast, unihemispheric BS is rare and its clinical significance is poorly understood. We describe here two cases of unihemispheric BS. The first patient is a 56-year-old woman with a left temporoparietal tumor who presented in convulsive status epilepticus. EEG showed left hemispheric BS after clinical seizure termination with lorazepam and propofol. The second patient is a 39-year-old woman with multiple medical problems and a vague history of seizures. After abdominal surgery, she experienced a convulsive seizure prompting treatment with propofol. Her EEG also showed left hemispheric BS. In both cases, increasing the propofol infusion rate resulted in disappearance of unihemispheric BS and clinical improvement. The prevailing view that typical bihemispheric BS is non-epileptic should not be extrapolated automatically to unihemispheric BS. The fact that unihemispheric BS was associated with clinical seizure and resolved with propofol suggests that, in both cases, an epileptic mechanism was responsible for unihemispheric BS. PMID:25309713

Villemarette-Pittman, Nicole R.; Rogers, Cornel T.; Torres-Delgado, Frank; Olejniczak, Piotr W.; England, John D.

2014-01-01

248

Lipidation by the Host Prenyltransferase Machinery Facilitates Membrane Localization of Legionella pneumophila Effector Proteins*  

PubMed Central

The intracellular human pathogen Legionella pneumophila translocates multiple proteins in the host cytosol known as effectors, which subvert host cellular processes to create a membrane-bound organelle that supports bacterial replication. It was observed that several Legionella effectors encode a prototypical eukaryotic prenylation CAAX motif (where C represents a cysteine residue and A denotes an aliphatic amino acid). These bacterial motifs mediated posttranslational modification of effector proteins resulting in the addition of either a farnesyl or geranylgeranyl isoprenyl lipid moiety to the cysteine residue of the CAAX tetrapeptide. Lipidation enhanced membrane affinity for most Legionella CAAX motif proteins and facilitated the localization of these effector proteins to host organelles. Host farnesyltransferase and class I geranylgeranyltransferase were both involved in the lipidation of the Legionella CAAX motif proteins. Perturbation of the host prenylation machinery during infection adversely affected the remodeling of the Legionella-containing vacuole. Thus, these data indicate that Legionella utilize the host prenylation machinery to facilitate targeting of effector proteins to membrane-bound organelles during intracellular infection. PMID:20813839

Ivanov, Stanimir S.; Charron, Guillaume; Hang, Howard C.; Roy, Craig R.

2010-01-01

249

Pharmacological Inhibition of TPL2/MAP3K8 Blocks Human Cytotoxic T Lymphocyte Effector Functions  

PubMed Central

CD8+ cytotoxic T lymphocytes (CTLs) play a major role in defense against intracellular pathogens. During development, antigen-presenting cells secrete innate cytokines such as IL-12 and IFN-?, which drive CTL differentiation into diverse populations of effector and long-lived memory cells. Using whole transcriptome analyses, the serine/threonine protein kinase Tpl2/MAP3K8 was found to be induced by IL-12 and selectively expressed by effector memory (TEM) CTLs. Tpl2 regulates various inflammatory pathways by activating the ERK mediated MAP kinase pathway in innate immune cells such as macrophages and dendritic cells. In this study, we found that a specific small molecule Tpl2 inhibitor blocked IFN-? and TNF-? secretion as well as cytolytic activity of human CTLs. This pathway was specific for human effector CTLs, as the Tpl2 inhibitor did not block IFN-? and TNF-? secretion from murine effector CTLs. Further, IL-12 failed to induce expression of Tpl2 in murine CTLs, and Tpl2 deficient murine CTLs did not exhibit any functional deficiency either in vitro or in vivo in response to L. monocytogenes infection. In summary, we identified a species-specific role for Tpl2 in effector function of human CTLs, which plays a major role in adaptive immune responses to intracellular pathogens and tumors. PMID:24642963

Chowdhury, Fatema Z.; Estrada, Leonardo D.; Murray, Sean; Forman, James; Farrar, J. David

2014-01-01

250

Myeloid cells as effector cells for monoclonal antibody therapy of cancer.  

PubMed

Monoclonal antibodies (mAbs) have become an important addition to chemo- and/or radiotherapy for the treatment of cancer. They have multiple effector functions that can lead to eradication of tumor, including induction of apoptosis, growth inhibition, and initiation of complement-dependent lysis. Furthermore, mAbs can recruit immune effector cells. Traditionally, natural killer cells have been considered as the main effector cell population in mAb-mediated tumor killing. Myeloid cells have potent cytotoxic ability, as well. Monocytes and macrophages have been shown to induce antibody-dependent cytotoxicity and phagocytosis of tumor cells in the presence of IgG anti-tumor mAb. Furthermore, neutrophils are the most abundant population of circulating white blood cells, and as such may constitute a formidable source of effector cells. However, when targeting neutrophils for tumor therapy, antibodies of the IgA subclass may be more effective. This article focuses on enlisting myeloid effector cells for mAb-based immunotherapy of cancer. Additionally, methods to study mAb-dependent phagocytosis of tumor cells by macrophages are compared. PMID:23811299

Braster, Rens; O'Toole, Tom; van Egmond, Marjolein

2014-01-01

251

Wind Tunnel Test of an RPV with Shape-Change Control Effector and Sensor Arrays  

NASA Technical Reports Server (NTRS)

A variety of novel control effector concepts have recently emerged that may enable new approaches to flight control. In particular, the potential exists to shift the composition of the typical aircraft control effector suite from a small number of high authority, specialized devices (rudder, aileron, elevator, flaps), toward larger numbers of smaller, less specialized, distributed device arrays. The concept envisions effector and sensor networks composed of relatively small high-bandwidth devices able to simultaneously perform a variety of control functions using feedback from disparate data sources. To investigate this concept, a remotely piloted flight vehicle has been equipped with an array of 24 trailing edge shape-change effectors and associated pressure measurements. The vehicle, called the Multifunctional Effector and Sensor Array (MESA) testbed, was recently tested in NASA Langley's 12-ft Low Speed wind tunnel to characterize its stability properties, control authorities, and distributed pressure sensitivities for use in a dynamic simulation prior to flight testing. Another objective was to implement and evaluate a scheme for actively controlling the spanwise pressure distribution using the shape-change array. This report describes the MESA testbed, design of the pressure distribution controller, and results of the wind tunnel test.

Raney, David L.; Cabell, Randolph H.; Sloan, Adam R.; Barnwell, William G.; Lion, S. Todd; Hautamaki, Bret A.

2004-01-01

252

Perturbation of host ubiquitin systems by plant pathogen/pest effector proteins  

PubMed Central

Microbial pathogens and pests of animals and plants secrete effector proteins into host cells, altering cellular physiology to the benefit of the invading parasite. Research in the past decade has delivered significant new insights into the molecular mechanisms of how these effector proteins function, with a particular focus on modulation of host immunity-related pathways. One host system that has emerged as a common target of effectors is the ubiquitination system in which substrate proteins are post-translationally modified by covalent conjugation with the small protein ubiquitin. This modification, typically via isopeptide bond formation through a lysine side chain of ubiquitin, can result in target degradation, relocalization, altered activity or affect protein–protein interactions. In this review, I focus primarily on how effector proteins from bacterial and filamentous pathogens of plants and pests perturb host ubiquitination pathways that ultimately include the 26S proteasome. The activities of these effectors, in how they affect ubiquitin pathways in plants, reveal how pathogens have evolved to identify and exploit weaknesses in this system that deliver increased pathogen fitness. PMID:25339602

Banfield, Mark J

2015-01-01

253

Brain microenvironment promotes the final functional maturation of tumor-specific effector CD8+ T cells.  

PubMed

During the priming phase of an antitumor immune response, CD8(+) T cells undergo a program of differentiation driven by professional APCs in secondary lymphoid organs. This leads to clonal expansion and acquisition both of effector functions and a specific adhesion molecule pattern. Whether this program can be reshaped during the effector phase to adapt to the effector site microenvironment is unknown. We investigated this in murine brain tumor models using adoptive transfer of tumor-specific CD8(+) T cells, and in spontaneous immune responses of patients with malignant glioma. Our data show proliferation of Ag-experienced tumor-specific T cells within the brain parenchyma. Moreover, CD8(+) T cells further differentiated in the brain, exhibiting enhanced IFN-gamma and granzyme B expression and induction of alpha(E)(CD103)beta(7) integrin. This unexpected integrin expression identified a subpopulation of CD8(+) T cells conditioned by the brain microenvironment and also had functional consequences: alpha(E)(CD103)beta(7)-expressing CD8(+) T cells had enhanced retention in the brain. These findings were further investigated for CD8(+) T cells infiltrating human malignant glioma; CD8(+) T cells expressed alpha(E)(CD103)beta(7) integrin and granzyme B as in the murine models. Overall, our data indicate that the effector site plays an active role in shaping the effector phase of tumor immunity. The potential for local expansion and functional reprogramming should be considered when optimizing future immunotherapies for regional tumor control. PMID:17617575

Masson, Frédérick; Calzascia, Thomas; Di Berardino-Besson, Wilma; de Tribolet, Nicolas; Dietrich, Pierre-Yves; Walker, Paul R

2007-07-15

254

Ras Effector Switching Promotes Divergent Cell Fates in C. elegans Vulval Patterning  

PubMed Central

SUMMARY The C. elegans vulva is patterned by epidermal growth factor (EGF) activation of Ras to control 1° fate, and 1° fate induces antagonistic Notch-dependent 2° fate. Furthermore, a spatial EGF gradient, in addition to inducing 1° fate, directly contributes to 2° fate via an unknown pathway. We find that in addition to its canonical effector, Raf, vulval Ras utilizes an exchange factor for the Ral small GTPase (RalGEF), such that Ras-RalGEF-Ral antagonizes Ras-Raf pro-1° fate activity. Consistent with its restricted expression pattern, Ral participates in EGF pro-2° activity. Thus, we have delineated a Ras effector-switching mechanism whereby position within the morphogen gradient dictates that Ras effector usage is switched to RalGEF from Raf to promote 2° instead of 1° fate. Our observations define the utility of Ras effector switching during normal development, and may provide a possible mechanistic basis for cell and cancer type differences in effector dependency and activation. PMID:21238927

Zand, Tanya P.; Reiner, David J.; Der, Channing J.

2010-01-01

255

An Unbiased Method for Clustering Bacterial Effectors Using Host Cellular Phenotypes  

PubMed Central

We present a novel method implementing unbiased high-content morphometric cell analysis to classify bacterial effector phenotypes. This clustering methodology represents a significant advance over more qualitative visual approaches and can also be used to classify, and therefore predict the likely function of, unknown effector genes from any microbial genome. As a proof of concept, we use this approach to investigate 23 genetic regions predicted to encode antimacrophage effectors located across the genome of the insect and human pathogen Photorhabdus asymbiotica. Statistical cluster analysis using multiple cellular measures categorized treated macrophage phenotypes into three major groups relating to their putative functionality: (i) adhesins, (ii) cytolethal toxins, and (iii) cytomodulating toxins. Further investigation into their effects on phagocytosis revealed that several effectors also modulate this function and that the nature of this modulation (increased or decreased phagocytosis) is linked to the phenotype cluster group. Categorizing potential functionalities in this way allows rapid functional follow-up of key candidates for more-directed cell biological or biochemical investigation. Such an unbiased approach to the classification of candidate effectors will be useful for describing virulence-related regions in a wide range of genomes and will be useful in assigning putative functions to the growing number of microbial genes whose function remains unclear from homology searching. PMID:24296505

Hodgson, David J.

2014-01-01

256

The EspF effector, a bacterial pathogen's Swiss army knife.  

PubMed

Central to the pathogenesis of many bacterial pathogens is the ability to deliver effector proteins directly into the cells of their eukaryotic host. EspF is one of many effector proteins exclusive to the attaching and effacing pathogen family that includes enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli. Work in recent years has revealed EspF to be one of the most multifunctional effector proteins known, with defined roles in several host cellular processes, including disruption of the epithelial barrier, antiphagocytosis, microvillus effacement, host membrane remodelling, modulation of the cytoskeleton, targeting and disruption of the nucleolus, intermediate filament disruption, cell invasion, mitochondrial dysfunction, apoptosis, and inhibition of several important epithelial transporters. Surprisingly, despite this high number of functions, EspF is a relatively small effector protein, and recent work has begun to decipher the molecular events that underlie its multifunctionality. This review focuses on the activities of EspF within the host cell and discusses recent findings and molecular insights relating to the virulence functions of this fascinating bacterial effector. PMID:20679436

Holmes, Ashleigh; Mühlen, Sabrina; Roe, Andrew J; Dean, Paul

2010-11-01

257

Antigen-Free Adjuvant Assists Late Effector CD4 T Cells to Transit to Memory in Lymphopenic Hosts  

PubMed Central

The events controlling the transition of T cells from effector to memory remain largely undefined. Many models have been put forth to account for the origin of memory precursors, but for CD4 T cells initial studies reported that memory T cells derive from IFN? non-producing effectors while others suggested that memory emanates from highly activated IFN?-producing effectors. Herein, using cell proliferation, expression of activation markers, and production of IFN? as a measure of activation, we defined two types of effector CD4 T cells and investigated memory generation. The moderately activated early effectors readily transit to memory while the highly activated late effectors, regardless of their IFN?-production, develop minimal memory. Boosting with antigen free adjuvant, however, rescues late effectors from cell death and sustains both survival and IFN? cytokine responses in lymphopenic hosts. The adjuvant-mediated memory transition of late effectors involves the function of toll-like receptors (TLRs) most notably TLR9. These findings uncover the mechanism by which late effector CD4 T cells are driven to transit to memory and suggest that timely boosts with adjuvant may enhance vaccine efficacy. PMID:23817422

Guloglu, F. Betul; Ellis, Jason S.; Wan, Xiaoxiao; Dhakal, Mermagya; Hoeman, Christine M.; Cascio, Jason A.; Zaghouani, Habib

2013-01-01

258

Antigen-free adjuvant assists late effector CD4 T cells to transit to memory in lymphopenic hosts.  

PubMed

The events controlling the transition of T cells from effector to memory remain largely undefined. Many models have been put forth to account for the origin of memory precursors, but for CD4 T cells initial studies reported that memory T cells derive from IFN-?-nonproducing effectors, whereas others suggested that memory emanates from highly activated IFN-?-producing effectors. In this study, using cell proliferation, expression of activation markers, and production of IFN-? as a measure of activation, we defined two types of effector CD4 T cells and investigated memory generation. The moderately activated early effectors readily transit to memory, whereas the highly activated late effectors, regardless of their IFN-? production, develop minimal memory. Boosting with Ag-free adjuvant, however, rescues late effectors from cell death and sustains both survival and IFN-? cytokine responses in lymphopenic hosts. The adjuvant-mediated memory transition of late effectors involves the function of TLRs, most notably TLR9. These findings uncover the mechanism by which late effector CD4 T cells are driven to transit to memory and suggest that timely boosts with adjuvant may enhance vaccine efficacy. PMID:23817422

Guloglu, F Betul; Ellis, Jason S; Wan, Xiaoxiao; Dhakal, Mermagya; Hoeman, Christine M; Cascio, Jason A; Zaghouani, Habib

2013-08-01

259

Toluene 4-Monooxygenase and its Complex with Effector Protein T4moD  

SciTech Connect

Toluene 4-monooxygenase (T4MO) is a multiprotein diiron enzyme complex that catalyzes the regiospecific oxidation of toluene to p-cresol. Catalytic function requires the presence of a small protein, called the effector protein. Effector protein exerts substantial control on the diiron hydroxylase catalytic cycle through protein-protein interactions. High-resolution crystal structures of the stoichometric hydroxylase and effector protein complex described here reveal how protein-protein interactions and reduction of the diiron center produce an active site configuration poised for reaction with O{sub 2}. Further information from crystal structures of mutated isoforms of the hydroxylase and a peroxo adduct is combined with catalytic results to give a fuller picture of the geometry of the enzyme-substrate complex used for the high fidelity oxidation of hydrocarbon substrates.

Bailey, Lucas J.; Fox, Brian G. (UW)

2012-10-16

260

Bacterial effectors target the plant cell nucleus to subvert host transcription  

PubMed Central

In order to promote virulence, Gram-negative bacteria have evolved the ability to inject so-called type III effector proteins into host cells. The plant cell nucleus appears to be a subcellular compartment repeatedly targeted by bacterial effectors. In agreement with this observation, mounting evidence suggests that manipulation of host transcription is a major strategy developed by bacteria to counteract plant defense responses. It has been suggested that bacterial effectors may adopt at least three alternative, although not mutually exclusive, strategies to subvert host transcription. T3Es may (1) act as transcription factors that directly activate transcription in host cells, (2) affect histone packing and chromatin configuration, and/or (3) directly target host transcription factor activity. Here, we provide an overview on how all these strategies may lead to host transcriptional re-programming and, as a result, to improved bacterial multiplication inside plant cells. PMID:22353865

Canonne, Joanne; Rivas, Susana

2012-01-01

261

Uncoupling T-cell expansion from effector differentiation in cell-based immunotherapy  

PubMed Central

Summary Adoptive cellular immunotherapy (ACT) is a potentially curative therapy for patients with advanced cancer. Eradication of tumor in mouse models and humans correlates with both a high dose of adoptively transferred cells and cells with a minimally differentiated phenotype that maintain replicative capacity and multipotency. We speculate that response to ACT not only requires transfer of cells with immediate cytolytic effector function to kill the bulk of fast-growing tumor, but also transfer of tumor-specific cells that maintain an ability for self-renewal and the capacity to produce a continual supply of cytolytic effector progeny until all malignant cells are eliminated. Current in vitro methods to expand cells to sufficient numbers and still maintain a minimally differentiated phenotype are hindered by the biological coupling of clonal expansion and effector differentiation. Therefore, a better understanding of the physiologic mechanism that couples cell expansion and differentiation in CD8+ T cells may improve the efficacy of ACT. PMID:24329803

2013-01-01

262

Learning-based position control of a closed-kinematic chain robot end-effector  

NASA Technical Reports Server (NTRS)

A trajectory control scheme whose design is based on learning theory, for a six-degree-of-freedom (DOF) robot end-effector built to study robotic assembly of NASA hardwares in space is presented. The control scheme consists of two control systems: the feedback control system and the learning control system. The feedback control system is designed using the concept of linearization about a selected operating point, and the method of pole placement so that the closed-loop linearized system is stabilized. The learning control scheme consisting of PD-type learning controllers, provides additional inputs to improve the end-effector performance after each trial. Experimental studies performed on a 2 DOF end-effector built at CUA, for three tracking cases show that actual trajectories approach desired trajectories as the number of trials increases. The tracking errors are substantially reduced after only five trials.

Nguyen, Charles C.; Zhou, Zhen-Lei

1990-01-01

263

Human-like characteristics for high degree of freedom robotic door-opening end-effector  

NASA Astrophysics Data System (ADS)

In the field of military Unmanned Ground Vehicles (UGV's), military units are forced to sweep largely populated cities and towns in search of hostile enemies. These urban types of operations are referred to as MOUT (Military Operations on Urban Terrain). During urban operations, these UGV's encounter difficulties when opening doors. Current manipulator end effectors have these difficulties, because they are not designed to mimic human hand operations. This paper explains the mechanical nature of the Modular Universal Door Opening End-effector (MUDOE). MUDOE is a result of our development research to improve robotic manipulators ability to negotiate closed doors. The presented solution has the ability to mimic human hand characteristics when opening doors. The end-effector possesses an ability to maintain a high Degree of Freedom (DoF), and grasp the doorknob by applying equally distributed forces to all points of contact.

Gray, Jeremy P.; Campagna, Frank

2011-05-01

264

The transcription factor PLZF (Zbtb16) directs the effector program of the NKT cell lineage  

PubMed Central

Summary The transcriptional control of CD1d-restricted NKT cell development has remained elusive. We report that PLZF (promyelocytic leukemia zinc finger; Zbtb16), a member of the BTB/POZ-ZF family of transcription factors which includes the CD4 lineage-specific c-Krox (Th-POK, Zbtb7b), is exquisitely specific to CD1d-restricted NKT cells and human MR1-specific MAIT cells. PLZF was induced immediately after positive selection of NKT cell precursors and PLZF-deficient NKT cells failed to undergo the intrathymic expansion and effector differentiation that characterize their lineage. Instead, they preserved a naïve phenotype and were directed to lymph nodes. Conversely, transgenic expression of PLZF induced CD4 thymocytes to acquire effector differentiation and migrate to non-lymphoid tissues. We suggest that PLZF is a transcriptional signature of NKT cells that directs their innate-like effector differentiation during thymic development. PMID:18703361

Savage, Adam K.; Constantinides, Michael G.; Han, Jin; Picard, Damien; Martin, Emmanuel; Li, Bofeng; Lantz, Olivier; Bendelac, Albert

2008-01-01

265

Mining the human gut microbiota for effector strains that shape the immune system.  

PubMed

The gut microbiota codevelops with the immune system beginning at birth. Mining the microbiota for bacterial strains responsible for shaping the structure and dynamic operations of the innate and adaptive arms of the immune system represents a formidable combinatorial problem but one that needs to be overcome to advance mechanistic understanding of microbial community and immune system coregulation and to develop new diagnostic and therapeutic approaches that promote health. Here, we discuss a scalable, less biased approach for identifying effector strains in complex microbial communities that impact immune function. The approach begins by identifying uncultured human fecal microbiota samples that transmit immune phenotypes to germ-free mice. Clonally arrayed sequenced collections of bacterial strains are constructed from representative donor microbiota. If the collection transmits phenotypes, effector strains are identified by testing randomly generated subsets with overlapping membership in individually housed germ-free animals. Detailed mechanistic studies of effector strain-host interactions can then be performed. PMID:24950201

Ahern, Philip P; Faith, Jeremiah J; Gordon, Jeffrey I

2014-06-19

266

Pressure suppression system  

DOEpatents

A pressure suppression system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and an enclosed gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The GDCS pool includes a plenum for receiving through an inlet the non-condensable gas carried with steam from the drywell following a loss-of-coolant accident (LOCA). A condenser is disposed in the GDCS plenum for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool following the LOCA and channeling steam released into the drywell following the LOCA into the GDCS plenum for cooling along with the non-condensable gas carried therewith for trapping the gas therein.

Gluntz, Douglas M. (San Jose, CA)

1994-01-01

267

Pressure suppression system  

DOEpatents

A pressure suppression system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and an enclosed gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The GDCS pool includes a plenum for receiving through an inlet the non-condensable gas carried with steam from the drywell following a loss-of-coolant accident (LOCA). A condenser is disposed in the GDCS plenum for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool following the LOCA and channeling steam released into the drywell following the LOCA into the GDCS plenum for cooling along with the non-condensable gas carried therewith for trapping the gas therein. 3 figs.

Gluntz, D.M.

1994-10-04

268

Interference suppression of SRS  

SciTech Connect

The theory of three-wave SRS is developed, which takes into account nonlinear dispersion of a medium for arbitrary phases of the pump waves at the input to the medium. The effect of interference suppression of SRS is predicted for values of the total phase of the three-wave pump (2n+1){pi} (n=0, {+-}1, {+-}2...), the effect being caused by the destructive interference of polarisations of the nonresonant dipole-allowed transitions. The relation between the contributions of the linear and nonlinear dispersions to the SRS is found. It is shown that at a sufficiently large wave detuning, the anti-Stokes wave amplitude experiences spatial oscillations. (nonlinear-optics phenomena)

Kochanov, V P [V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2011-01-24

269

Coxiella burnetii Effector Proteins That Localize to the Parasitophorous Vacuole Membrane Promote Intracellular Replication.  

PubMed

The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a parasitophorous vacuole (PV) that acquires host endolysosomal components. Formation of a PV that supports C. burnetii replication requires a Dot/Icm type 4B secretion system (T4BSS) that delivers bacterial effector proteins into the host cell cytosol. Thus, a subset of T4BSS effectors are presumed to direct PV biogenesis. Recently, the PV-localized effector protein CvpA was found to promote C. burnetii intracellular growth and PV expansion. We predict additional C. burnetii effectors localize to the PV membrane and regulate eukaryotic vesicle trafficking events that promote pathogen growth. To identify these vacuolar effector proteins, a list of predicted C. burnetii T4BSS substrates was compiled using bioinformatic criteria, such as the presence of eukaryote-like coiled-coil domains. Adenylate cyclase translocation assays revealed 13 proteins were secreted in a Dot/Icm-dependent fashion by C. burnetii during infection of human THP-1 macrophages. Four of the Dot/Icm substrates, termed Coxiella vacuolar protein B (CvpB), CvpC, CvpD, and CvpE, labeled the PV membrane and LAMP1-positive vesicles when ectopically expressed as fluorescently tagged fusion proteins. C. burnetii ?cvpB, ?cvpC, ?cvpD, and ?cvpE mutants exhibited significant defects in intracellular replication and PV formation. Genetic complementation of the ?cvpD and ?cvpE mutants rescued intracellular growth and PV generation, whereas the growth of C. burnetii ?cvpB and ?cvpC was rescued upon cohabitation with wild-type bacteria in a common PV. Collectively, these data indicate C. burnetii encodes multiple effector proteins that target the PV membrane and benefit pathogen replication in human macrophages. PMID:25422265

Larson, Charles L; Beare, Paul A; Voth, Daniel E; Howe, Dale; Cockrell, Diane C; Bastidas, Robert J; Valdivia, Raphael H; Heinzen, Robert A

2015-02-01

270

Bacterial Toxin Effector-Membrane Targeting: Outside in, then Back Again  

PubMed Central

Pathogenic bacteria utilize multiple approaches to establish infection and mediate their toxicity to eukaryotic cells. Dedicated protein machines deposit toxic effectors directly inside the host, whereas secreted toxins must enter cells independently of other bacterial components. Regardless of how they reach the cytosol, these bacterial proteins must accurately identify their intracellular target before they can manipulate the host cell to benefit their associated bacteria. Within eukaryotic cells, post-translational modifications and individual targeting motifs spatially regulate endogenous host proteins. This review focuses on the strategies employed by bacterial effectors to associate with a frequently targeted location within eukaryotic cells, the plasma membrane. PMID:22919666

Geissler, Brett

2012-01-01

271

Platelets: versatile effector cells in hemostasis, inflammation, and the immune continuum  

PubMed Central

Platelets are chief effector cells in hemostasis. In addition, however, their specializations include activities and intercellular interactions that make them key effectors in inflammation and in the continuum of innate and adaptive immunity. This review focuses on the immune features of human platelets and platelets from experimental animals and on interactions between inflammatory, immune, and hemostatic activities of these anucleate but complex and versatile cells. The experimental findings and evidence for physiologic immune functions include previously unrecognized biologic characteristics of platelets and are paralleled by new evidence for unique roles of platelets in inflammatory, immune, and thrombotic diseases. PMID:21818701

Vieira-de-Abreu, Adriana; Campbell, Robert A.; Weyrich, Andrew S.

2015-01-01

272

Transcriptional control of effector and memory CD8+ T cell differentiation  

PubMed Central

During an infection, T cells can differentiate into multiple types of effector and memory T cells, which help to mediate pathogen clearance and provide long-term protective immunity. These cells can vary in their phenotype, function and location, and in their long-term fate in terms of their ability to populate the memory T cell pool. Over the past decade, the signalling pathways and transcriptional programmes that regulate the formation of heterogeneous populations of effector and memory CD8+ T cells have started to be characterized, and this Review discusses the major advances in these areas. PMID:23080391

Kaech, Susan M.; Cui, Weiguo

2014-01-01

273

Terrific Protein Traffic: The Mystery of Effector Protein Delivery by Filamentous Plant Pathogens  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Many biotrophic fungal and oomycete plant pathogens deliver effector proteins directly into host cells during infection. Recent advances are revealing the extensive effector repertoires of these pathogens and are beginning to shed light on how they manipulate host cells to establish a parasitic relationship. The current explosion of information is opening new research avenues in molecular plant pathology and is providing new opportunities to limit the impact of plant disease on food production.

Ralph Panstruga (Max-Planck Institute for Plant Breeding Research; Department of Plant-Microbe Interactions)

2009-05-08

274

Searching algorithm for type IV secretion system effectors 1.0: a tool for predicting type IV effectors and exploring their genomic context  

PubMed Central

Type IV effectors (T4Es) are proteins produced by pathogenic bacteria to manipulate host cell gene expression and processes, divert the cell machinery for their own profit and circumvent the immune responses. T4Es have been characterized for some bacteria but many remain to be discovered. To help biologists identify putative T4Es from the complete genome of ?- and ?-proteobacteria, we developed a Perl-based command line bioinformatics tool called S4TE (searching algorithm for type-IV secretion system effectors). The tool predicts and ranks T4E candidates by using a combination of 13 sequence characteristics, including homology to known effectors, homology to eukaryotic domains, presence of subcellular localization signals or secretion signals, etc. S4TE software is modular, and specific motif searches are run independently before ultimate combination of the outputs to generate a score and sort the strongest T4Es candidates. The user keeps the possibility to adjust various searching parameters such as the weight of each module, the selection threshold or the input databases. The algorithm also provides a GC% and local gene density analysis, which strengthen the selection of T4E candidates. S4TE is a unique predicting tool for T4Es, finding its utility upstream from experimental biology. PMID:23945940

Meyer, Damien F.; Noroy, Christophe; Moumène, Amal; Raffaele, Sylvain; Albina, Emmanuel; Vachiéry, Nathalie

2013-01-01

275

Insect antiviral innate immunity: pathways, effectors, and connections  

PubMed Central

Insects are infected by a wide array of viruses some of which are insect-restricted and pathogenic, and some of which are transmitted by biting insects to vertebrates. The medical and economic importance of these viruses heightens the need to understand the interaction between the infecting pathogen and the insect immune system in order to develop transmission interventions. The interaction of the virus with the insect host innate immune system plays a critical role in the outcome of infection. The major mechanism of antiviral defense is the siRNA pathway that responds through the detection of virus-derived dsRNA to suppress virus replication. However, other innate antimicrobial pathways such as Imd, Toll, Jak-STAT, and the autophagy pathway have also been shown to play important roles in antiviral immunity. In this review we provide an overview of the current understanding of the main insect antiviral pathways and examine recent findings that further our understanding of the roles of these pathways in facilitating a systemic and specific response to infecting viruses. PMID:24120681

Kingsolver, Megan B.; Huang, Zhijing; Hardy, Richard W.

2014-01-01

276

Insect antiviral innate immunity: pathways, effectors, and connections.  

PubMed

Insects are infected by a wide array of viruses some of which are insect restricted and pathogenic, and some of which are transmitted by biting insects to vertebrates. The medical and economic importance of these viruses heightens the need to understand the interaction between the infecting pathogen and the insect immune system in order to develop transmission interventions. The interaction of the virus with the insect host innate immune system plays a critical role in the outcome of infection. The major mechanism of antiviral defense is the small, interfering RNA pathway that responds through the detection of virus-derived double-stranded RNA to suppress virus replication. However, other innate antimicrobial pathways such as Imd, Toll, and Jak-STAT and the autophagy pathway have also been shown to play important roles in antiviral immunity. In this review, we provide an overview of the current understanding of the main insect antiviral pathways and examine recent findings that further our understanding of the roles of these pathways in facilitating a systemic and specific response to infecting viruses. PMID:24120681

Kingsolver, Megan B; Huang, Zhijing; Hardy, Richard W

2013-12-13

277

STRV CRYOCOOLER TIP MOTION SUPPRESSION  

Microsoft Academic Search

The Space Technology Research Vehicle (STRV- lb) scheduled to fly at the beginning of June 1994, has a cryocooler vibration suppression experiment aboard doing motion suppression of the tip of the coldfinger. STRV-lb is a bread box sized satellite to be launched on the next flight of the Ariane-4. To meet stringent power, weight, and space constraints, the experiment uses

R. Glascr; R. G. Ross

278

STRV Cryocooler Tip Motion Suppression  

NASA Technical Reports Server (NTRS)

The Space Technology Research Vehicle (STRV-1b) scheduled to fly at the beginning of June 1994, has a cryocooler vibration suppression experiment aboard doing motion suppression of the tip of the coldfinger. STRV-1b is a bread box sized satellite to be launched on the next flight of the Ariane-4.

Glaser, R.; Ross, R. G., Jr.; Johnson, D. L.

1994-01-01

279

An Alternative to Thought Suppression?  

ERIC Educational Resources Information Center

Comments on the original article, "Setting free the bears: Escape from thought suppression," by D. M. Wegner (see record 2011-25622-008). While Wegner supposed that we might have to learn to live with bad thoughts, the present author discusses the use of imagination and guided imagery as an alternative to forced thought suppression.

Boice, Robert

2012-01-01

280

Identification, Structure, and Function of a Novel Type VI Secretion Peptidoglycan Glycoside Hydrolase Effector-Immunity Pair*  

PubMed Central

Bacteria employ type VI secretion systems (T6SSs) to facilitate interactions with prokaryotic and eukaryotic cells. Despite the widespread identification of T6SSs among Gram-negative bacteria, the number of experimentally validated substrate effector proteins mediating these interactions remains small. Here, employing an informatics approach, we define novel families of T6S peptidoglycan glycoside hydrolase effectors. Consistent with the known intercellular self-intoxication exhibited by the T6S pathway, we observe that each effector gene is located adjacent to a hypothetical open reading frame encoding a putative periplasmically localized immunity determinant. To validate our sequence-based approach, we functionally investigate a representative family member from the soil-dwelling bacterium Pseudomonas protegens. We demonstrate that this protein is secreted in a T6SS-dependent manner and that it confers a fitness advantage in growth competition assays with Pseudomonas putida. In addition, we determined the 1.4 ? x-ray crystal structure of this effector in complex with its cognate immunity protein. The structure reveals the effector shares highest overall structural similarity to a glycoside hydrolase family associated with peptidoglycan N-acetylglucosaminidase activity, suggesting that T6S peptidoglycan glycoside hydrolase effector families may comprise significant enzymatic diversity. Our structural analyses also demonstrate that self-intoxication is prevented by the immunity protein through direct occlusion of the effector active site. This work significantly expands our current understanding of T6S effector diversity. PMID:23878199

Whitney, John C.; Chou, Seemay; Russell, Alistair B.; Biboy, Jacob; Gardiner, Taylor E.; Ferrin, Michael A.; Brittnacher, Mitchell; Vollmer, Waldemar; Mougous, Joseph D.

2013-01-01

281

A Meloidogyne incognita effector is imported into the nucleus and exhibits transcriptional activation activity in?planta.  

PubMed

Root-knot nematodes are sedentary biotrophic endoparasites that maintain a complex interaction with their host plants. Nematode effector proteins are synthesized in the oesophageal glands of nematodes and secreted into plant tissue through a needle-like stylet. Effectors characterized to date have been shown to mediate processes essential for nematode pathogenesis. To gain an insight into their site of action and putative function, the subcellular localization of 13 previously isolated Meloidogyne incognita effectors was determined. Translational fusions were created between effectors and EGFP-GUS (enhanced green fluorescent protein-?-glucuronidase) reporter genes, which were transiently expressed in tobacco leaf cells. The majority of effectors localized to the cytoplasm, with one effector, 7H08, imported into the nuclei of plant cells. Deletion analysis revealed that the nuclear localization of 7H08 was mediated by two novel independent nuclear localization domains. As a result of the nuclear localization of the effector, 7H08 was tested for the ability to activate gene transcription. 7H08 was found to activate the expression of reporter genes in both yeast and plant systems. This is the first report of a plant-parasitic nematode effector with transcriptional activation activity. PMID:24863562

Zhang, Lei; Davies, Laura J; Elling, Axel A

2015-01-01

282

Identification, structure, and function of a novel type VI secretion peptidoglycan glycoside hydrolase effector-immunity pair.  

PubMed

Bacteria employ type VI secretion systems (T6SSs) to facilitate interactions with prokaryotic and eukaryotic cells. Despite the widespread identification of T6SSs among Gram-negative bacteria, the number of experimentally validated substrate effector proteins mediating these interactions remains small. Here, employing an informatics approach, we define novel families of T6S peptidoglycan glycoside hydrolase effectors. Consistent with the known intercellular self-intoxication exhibited by the T6S pathway, we observe that each effector gene is located adjacent to a hypothetical open reading frame encoding a putative periplasmically localized immunity determinant. To validate our sequence-based approach, we functionally investigate a representative family member from the soil-dwelling bacterium Pseudomonas protegens. We demonstrate that this protein is secreted in a T6SS-dependent manner and that it confers a fitness advantage in growth competition assays with Pseudomonas putida. In addition, we determined the 1.4 ? x-ray crystal structure of this effector in complex with its cognate immunity protein. The structure reveals the effector shares highest overall structural similarity to a glycoside hydrolase family associated with peptidoglycan N-acetylglucosaminidase activity, suggesting that T6S peptidoglycan glycoside hydrolase effector families may comprise significant enzymatic diversity. Our structural analyses also demonstrate that self-intoxication is prevented by the immunity protein through direct occlusion of the effector active site. This work significantly expands our current understanding of T6S effector diversity. PMID:23878199

Whitney, John C; Chou, Seemay; Russell, Alistair B; Biboy, Jacob; Gardiner, Taylor E; Ferrin, Michael A; Brittnacher, Mitchell; Vollmer, Waldemar; Mougous, Joseph D

2013-09-13

283

Tomato immune receptor Ve1 recognizes effector of multiple fungal pathogens uncovered by genome and RNA sequencing  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fungal plant pathogens secrete effector molecules to establish disease on their hosts, while plants in turn utilize immune receptors to intercept these effectors. The tomato immune receptor Ve1 governs resistance to race 1 strains of the soil-borne vascular wilt fungi Verticillium dahliae and V. alb...

284

Cdc42 Effector Protein 2 (XCEP2) is required for normal gastrulation and contributes to cellular adhesion in Xenopus laevis  

Microsoft Academic Search

BACKGROUND: Rho GTPases and their downstream effector proteins regulate a diverse array of cellular processes during embryonic development, including reorganization of cytoskeletal architecture, cell adhesion, and transcription. Changes in the activation state of Rho GTPases are converted into changes in cellular behavior by a diversity of effector proteins, which are activated in response to changes in the GTP binding state

Karen K Nelson; Richard W Nelson

2004-01-01

285

IL-2 simultaneously expands Foxp3+ T regulatory and T effector cells and confers resistance to severe tuberculosis (TB): implicative Treg-T effector cooperation in immunity to TB.  

PubMed

The possibility that simultaneous expansion of T regulatory cells (Treg) and T effector cells early postinfection can confer some immunological benefits has not been studied. In this study, we tested the hypothesis that early, simultaneous cytokine expansion of Treg and T effector cells in a tissue infection site can allow these T cell populations to act in concert to control tissue inflammation/damage while containing infection. IL-2 treatments early after Mycobacterium tuberculosis infection of macaques induced simultaneous expansion of CD4(+)CD25(+)Foxp3(+) Treg, CD8(+)CD25(+)Foxp3(+) T cells, and CD4(+) T effector/CD8(+) T effector/V?2V?2 T effector populations producing anti-M. tuberculosis cytokines IFN-? and perforin, and conferred resistance to severe TB inflammation and lesions. IL-2-expanded Foxp3(+) Treg readily accumulated in pulmonary compartment, but despite this, rapid pulmonary trafficking/accumulation of IL-2-activated T effector populations still occurred. Such simultaneous recruitments of IL-2-expanded Treg and T effector populations to pulmonary compartment during M. tuberculosis infection correlated with IL-2-induced resistance to TB lesions without causing Treg-associated increases in M. tuberculosis burdens. In vivo depletion of IL-2-expanded CD4(+)Foxp3(+) Treg and CD4(+) T effectors during IL-2 treatment of M. tuberculosis-infected macaques significantly reduced IL-2-induced resistance to TB lesions, suggesting that IL-2-expanded CD4(+) T effector cells and Treg contributed to anti-TB immunity. Thus, IL-2 can simultaneously activate and expand T effector cells and Foxp3(+) Treg populations and confer resistance to severe TB without enhancing M. tuberculosis infection. PMID:22474020

Chen, Crystal Y; Huang, Dan; Yao, Shuyu; Halliday, Lisa; Zeng, Gucheng; Wang, Richard C; Chen, Zheng W

2012-05-01

286

IL-2 Simultaneously Expands Foxp3+ T Regulatory and T Effector Cells and Confers Resistance to Severe Tuberculosis (TB): Implicative Treg–T Effector Cooperation in Immunity to TB  

PubMed Central

The possibility that simultaneous expansion of T regulatory cells (Treg) and T effector cells early postinfection can confer some immunological benefits has not been studied. In this study, we tested the hypothesis that early, simultaneous cytokine expansion of Treg and T effector cells in a tissue infection site can allow these T cell populations to act in concert to control tissue inflammation/damage while containing infection. IL-2 treatments early after Mycobacterium tuberculosis infection of macaques induced simultaneous expansion of CD4+CD25+Foxp3+ Treg, CD8+CD25+Foxp3+ T cells, and CD4+ T effector/CD8+ T effector/V?2V?2 T effector populations producing anti-M. tuberculosis cytokines IFN-? and perforin, and conferred resistance to severe TB inflammation and lesions. IL-2–expanded Foxp3+ Treg readily accumulated in pulmonary compartment, but despite this, rapid pulmonary trafficking/accumulation of IL-2–activated T effector populations still occurred. Such simultaneous recruitments of IL-2–expanded Treg and T effector populations to pulmonary compartment during M. tuberculosis infection correlated with IL-2–induced resistance to TB lesions without causing Treg-associated increases in M. tuberculosis burdens. In vivo depletion of IL-2–expanded CD4+Foxp3+ Treg and CD4+ T effectors during IL-2 treatment of M. tuberculosis-infected macaques significantly reduced IL-2–induced resistance to TB lesions, suggesting that IL-2–expanded CD4+ T effector cells and Treg contributed to anti-TB immunity. Thus, IL-2 can simultaneously activate and expand T effector cells and Foxp3+ Treg populations and confer resistance to severe TB without enhancing M. tuberculosis infection. PMID:22474020

Chen, Crystal Y.; Huang, Dan; Yao, Shuyu; Halliday, Lisa; Zeng, Gucheng; Wang, Richard C.; Chen, Zheng W.

2012-01-01

287

The transcription factor BATF operates as an essential differentiation checkpoint in early effector CD8+ T cells  

PubMed Central

The transcription factor BATF is required for interleukin 17 (IL-17)-producing helper T cell (TH17) and follicular helper T cell (TFH) differentiation. Here, we show that BATF also has a fundamental role in regulating effector CD8+ T cell differentiation. BATF-deficient CD8+ T cells show profound defects in effector expansion and undergo proliferative and metabolic catastrophe early after antigen encounter. BATF, together with IRF4 and Jun proteins, binds to and promotes early expression of genes encoding lineage-specific transcription-factors (T-bet and Blimp-1) and cytokine receptors, while paradoxically repressing genes encoding effector molecules (IFN-? and granzyme B). Thus, BATF amplifies TCR-dependent transcription factor expression and augments inflammatory signal propagation but restrains effector gene expression. This checkpoint prevents irreversible commitment to an effector fate until a critical threshold of downstream transcriptional activity has been achieved. PMID:24584090

Kurachi, Makoto; Barnitz, R. Anthony; Yosef, Nir; Odorizzi, Pamela M.; Dilorio, Michael A.; Lemieux, Madeleine E.; Yates, Kathleen; Godec, Jernej; Klatt, Martin G.; Regev, Aviv; Wherry, E. John; Haining, W. Nicholas

2014-01-01

288

Isoflavones, Genistein and Daidzein, Regulate Mucosal Immune Response by Suppressing Dendritic Cell Function  

PubMed Central

Lipopolysaccharide (LPS), a component of gram-negative bacterial cell walls, has been shown to have a strong adjuvant effect towards inhaled antigens contributing to airway inflammation. Isoflavones are anti-inflammatory molecules present in abundant quantities in soybeans. We investigated the effect of isoflavones on human dendritic cell (DC) activation via LPS stimulation and subsequent DC-mediated effector cell function both in vitro and in a mouse model of upper airway inflammation. Human monocyte-derived DCs (MDDC) were matured with LPS (or TNF-?) +/? isoflavones (genistein or daidzein). The surface expression levels of DC activation markers were analyzed by flow cytometry. Mature DCs +/? isoflavones were washed and cultured with freshly-isolated allogenic naïve CD4+ T cells for 5 days or with autologous natural killer (NK) cells for 2 hours. The percentages of proliferating IFN-?+ CD4+ T cells and cytokine levels in culture supernatants were assessed. NK cell degranulation and DC cytotoxicity were measured by flow cytometry. Isoflavones significantly suppressed the activation-induced expression of DC maturation markers (CD83, CD80, CD86) and MHC class I but not MHC class II molecules in vitro. Isoflavone treatment inhibited the ability of LPS-DCs to induce IFN-? in CD4+ T cells. NK cell degranulation and the percentage of dead DCs were significantly increased in isoflavone-treated DC-NK co-culture experiments. Dietary isoflavones suppressed the mucosal immune response to intra-nasal sensitization of mice to ovalbumin. Similar results were obtained when isoflavones were co-administered during sensitization. These results demonstrate that soybean isoflavones suppress immune sensitization by suppressing DC-maturation and its subsequent DC-mediated effector cell functions. PMID:23110148

Wei, John; Bhatt, Shiven; Chang, Lisa M.; Sampson, Hugh A.; Masilamani, Madhan

2012-01-01

289

Oncogenic KRAS Impairs EGFR Antibodies' Efficiency by C/EBP?-Dependent Suppression of EGFR Expression12  

PubMed Central

Oncogenic KRAS mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR)-directed antibody (Ab) therapy. However, the mechanisms by which constitutively activated KRAS (KRASG12V) impairs effector mechanisms of EGFR-Abs are incompletely understood. Here, we established isogenic cell line models to systematically investigate the impact of KRASG12V on tumor growth in mouse A431 xenograft models as well as on various modes of action triggered by EGFR-Abs in vitro. KRASG12V impaired EGFR-Ab-mediated growth inhibition by stimulating receptor-independent downstream signaling. KRASG12V also rendered tumor cells less responsive to Fc-mediated effector mechanisms of EGFR-Abs—such as complement-dependent cytotoxicity (CDC) and Ab-dependent cell-mediated cytotoxicity (ADCC). Impaired CDC and ADCC activities could be linked to reduced EGFR expression in KRAS-mutated versus wild-type (wt) cells, which was restored by small interfering RNA (siRNA)-mediated knockdown of KRAS4b. Immunohistochemistry experiments also revealed lower EGFR expression in KRAS-mutated versus KRAS-wt harboring CRC samples. Analyses of potential mechanisms by which KRASG12V downregulated EGFR expression demonstrated significantly decreased activity of six distinct transcription factors. Additional experiments suggested the CCAAT/enhancer-binding protein (C/EBP) family to be implicated in the regulation of EGFR promoter activity in KRAS-mutated tumor cells by suppressing EGFR transcription through up-regulation of the inhibitory family member C/EBP?-LIP. Thus, siRNA-mediated knockdown of C/EBP? led to enhanced EGFR expression and Ab-mediated cytotoxicity against KRAS-mutated cells. Together, these results demonstrate that KRASG12V signaling induced C/EBP?-dependent suppression of EGFR expression, thereby impairing Fc-mediated effector mechanisms of EGFR-Abs and rendering KRAS-mutated tumor cells less sensitive to these therapeutic agents. PMID:22496619

Derer, Stefanie; Berger, Sven; Schlaeth, Martin; Schneider-Merck, Tanja; Klausz, Katja; Lohse, Stefan; Overdijk, Marije B; Dechant, Michael; Kellner, Christian; Nagelmeier, Iris; Scheel, Andreas H; Lammerts van Bueren, Jeroen J; van de Winkel, Jan GJ; Parren, Paul WHI; Peipp, Matthias; Valerius, Thomas

2012-01-01

290

Mechanism of IRSp53 inhibition and combinatorial activation by Cdc42 and downstream effectors  

PubMed Central

The Rho family GTPase effector IRSp53 has essential roles in filopodia formation and neuronal development, but its regulatory mechanism is poorly understood. IRSp53 contains a membrane-binding BAR domain followed by an unconventional CRIB motif that overlaps with a proline-rich region (CRIB–PR) and an SH3 domain that recruits actin cytoskeleton effectors. Using a fluorescence reporter assay, we show that human IRSp53 adopts a closed inactive conformation that opens synergistically with the binding of human Cdc42 to the CRIB–PR and effector proteins, such as the tumor-promoting factor Eps8, to the SH3 domain. The crystal structure of Cdc42 bound to the CRIB–PR reveals a new mode of effector binding to Rho family GTPases. Structure-inspired mutations disrupt autoinhibition and Cdc42 binding in vitro and decouple Cdc42- and IRSp53-dependent filopodia formation in cells. The data support a combinatorial mechanism of IRSp53 activation. PMID:24584464

Kast, David J; Yang, Changsong; Disanza, Andrea; Boczkowska, Malgorzata; Madasu, Yadaiah; Scita, Giorgio; Svitkina, Tatyana; Dominguez, Roberto

2014-01-01

291

Mutualistic co-evolution of type III effector genes in Sinorhizobium fredii and Bradyrhizobium japonicum.  

PubMed

Two diametric paradigms have been proposed to model the molecular co-evolution of microbial mutualists and their eukaryotic hosts. In one, mutualist and host exhibit an antagonistic arms race and each partner evolves rapidly to maximize their own fitness from the interaction at potential expense of the other. In the opposing model, conflicts between mutualist and host are largely resolved and the interaction is characterized by evolutionary stasis. We tested these opposing frameworks in two lineages of mutualistic rhizobia, Sinorhizobium fredii and Bradyrhizobium japonicum. To examine genes demonstrably important for host-interactions we coupled the mining of genome sequences to a comprehensive functional screen for type III effector genes, which are necessary for many Gram-negative pathogens to infect their hosts. We demonstrate that the rhizobial type III effector genes exhibit a surprisingly high degree of conservation in content and sequence that is in contrast to those of a well characterized plant pathogenic species. This type III effector gene conservation is particularly striking in the context of the relatively high genome-wide diversity of rhizobia. The evolution of rhizobial type III effectors is inconsistent with the molecular arms race paradigm. Instead, our results reveal that these loci are relatively static in rhizobial lineages and suggest that fitness conflicts between rhizobia mutualists and their host plants have been largely resolved. PMID:23468637

Kimbrel, Jeffrey A; Thomas, William J; Jiang, Yuan; Creason, Allison L; Thireault, Caitlin A; Sachs, Joel L; Chang, Jeff H

2013-02-01

292

Position and Velocity Transformations Between Robot End-Effector Coordinates and Joint Angles  

Microsoft Academic Search

This paper describes efficient procedures for performing transformations from the position and velocity of the end effector to the corresponding joint angles and velocities, and vice versa, for a six-degree-of-freedom robot manipulator having three revolute joint axes intersecting at the wrist. Some attention is paid to the problems that arise when the manipulator's position is near a deadpoint.

R. Featherstone

1983-01-01

293

Characterization of plant – fungal interactions involving necrotrophic effector-producing plant pathogens  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recently, great strides have been made in the area of host-pathogen interactions involving necrotrophic fungi. In this article we describe a method to identify, produce, and characterize effectors that are important in host –necrotrophic fungal pathogen interactions, and to genetically characterize...

294

An evolving autoimmune microenvironment regulates the quality of effector T cell restimulation and function  

PubMed Central

Defining the processes of autoimmune attack of tissues is important for inhibiting continued tissue destruction. In type 1 diabetes, it is not known how cytotoxic effector T cell responses evolve over time in the pancreatic islets targeted for destruction. We used two-photon microscopy of live, intact, individual islets to investigate how progression of islet infiltration altered the behavior of infiltrating islet-specific CD8+ T cells. During early-islet infiltration, T-cell interactions with CD11c+ antigen-presenting cells (APCs) were stable and real-time imaging of T cell receptor (TCR) clustering provided evidence of TCR recognition in these stable contacts. Early T cell–APC encounters supported production of IFN-? by T effectors, and T cells at this stage also killed islet APCs. At later stages of infiltration, T-cell motility accelerated, and cytokine production was lost despite the presence of higher numbers of infiltrating APCs that were able to trigger T-cell signaling in vitro. Using timed introduction of effector T cells, we demonstrate that elements of the autoimmune-tissue microenvironment control the dynamics of autoantigen recognition by T cells and their resulting pathogenic effector functions. PMID:24927530

Friedman, Rachel S.; Lindsay, Robin S.; Lilly, Jason K.; Nguyen, Vinh; Sorensen, Caitlin M.; Jacobelli, Jordan; Krummel, Matthew F.

2014-01-01

295

Effector-Dependent Learning by Observation of a Finger Movement Sequence  

ERIC Educational Resources Information Center

Can observational learning be effector dependent? In 3 experiments, observers watched a model respond to a 6-item unique sequence in a serial reaction time task. Their sequence knowledge was then compared with that of controls who had performed an unrelated task or observed a model responding to random targets. Observational learning was indicated…

Bird, Geoffrey; Heyes, Cecilia

2005-01-01

296

Antigen independent differentiation and maintenance of effector-like resident memory T cells in tissues  

PubMed Central

Differentiation and maintenance of recirculating effector memory CD8 T cells (TEM) depends on prolonged cognate antigen stimulation. Whether similar pathways of differentiation exist for recently identified tissue-resident effector memory T cells (TRM), which contribute to rapid local protection upon pathogen re-exposure, is unknown. Memory CD8??+ T cells within small intestine epithelium are well-characterized examples of TRM and they maintain a long-lived effector-like phenotype that is highly suggestive of persistent antigen stimulation. This study sought to define the sources and requirements for prolonged Ag-stimulation in programming this differentiation state, including local stimulation via cognate or cross-reactive antigens derived from pathogens, microbial flora, or dietary proteins. Contrary to expectations, we found that prolonged cognate Ag-stimulation was dispensable for intestinal TRM ontogeny. In fact, chronic antigenic stimulation skewed differentiation away from the canonical intestinal T cell phenotype. Resident memory signatures, CD69 and CD103, were expressed in many non-lymphoid tissues including intestine, stomach, kidney, reproductive tract, pancreas, brain, heart, and salivary gland, and could be driven by cytokines. Moreover, TGF? driven CD103 expression was required for TRM maintenance within intestinal epithelium in vivo. Thus, induction and maintenance of long-lived effector-like intestinal TRM differed from classic models of TEM ontogeny, and were programmed through a novel location-dependent pathway that was required for the persistence of local immunological memory. PMID:22504644

Casey, Kerry A; Fraser, Kathryn A; Schenkel, Jason M; Moran, Amy; Abt, Michael C; Beura, Lalit K; Lucas, Philip J; Artis, David; Wherry, E John; Hogquist, Kristin; Vezys, Vaiva; Masopust, David

2012-01-01

297

ORIGINAL ARTICLE Irradiation induces DNA damage and modulates epigenetic effectors in  

E-print Network

ORIGINAL ARTICLE Irradiation induces DNA damage and modulates epigenetic effectors in distant of Technology, Cambridge, MA, USA Irradiated cells induce chromosomal instability in uni- rradiated bystander tissues in vivo. Here, we describe studies in which mice were unilaterally exposed to X-irradiation

Engelward, Bevin

298

Mechanism of IRSp53 inhibition and combinatorial activation by Cdc42 and downstream effectors.  

PubMed

The Rho family GTPase effector IRSp53 has essential roles in filopodia formation and neuronal development, but its regulatory mechanism is poorly understood. IRSp53 contains a membrane-binding BAR domain followed by an unconventional CRIB motif that overlaps with a proline-rich region (CRIB-PR) and an SH3 domain that recruits actin cytoskeleton effectors. Using a fluorescence reporter assay, we show that human IRSp53 adopts a closed inactive conformation that opens synergistically with the binding of human Cdc42 to the CRIB-PR and effector proteins, such as the tumor-promoting factor Eps8, to the SH3 domain. The crystal structure of Cdc42 bound to the CRIB-PR reveals a new mode of effector binding to Rho family GTPases. Structure-inspired mutations disrupt autoinhibition and Cdc42 binding in vitro and decouple Cdc42- and IRSp53-dependent filopodia formation in cells. The data support a combinatorial mechanism of IRSp53 activation. PMID:24584464

Kast, David J; Yang, Changsong; Disanza, Andrea; Boczkowska, Malgorzata; Madasu, Yadaiah; Scita, Giorgio; Svitkina, Tatyana; Dominguez, Roberto

2014-04-01

299

A bacterial effector targets host DH-PH domain RhoGEFs and antagonizes macrophage phagocytosis  

PubMed Central

Bacterial pathogens often harbour a type III secretion system (TTSS) that injects effector proteins into eukaryotic cells to manipulate host processes and cause diseases. Identification of host targets of bacterial effectors and revealing their mechanism of actions are crucial for understating bacterial virulence. We show that EspH, a type III effector conserved in enteric bacterial pathogens including enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic E. coli and Citrobacter rodentium, markedly disrupts actin cytoskeleton structure and induces cell rounding up when ectopically expressed or delivered into HeLa cells by the bacterial TTSS. EspH inactivates host Rho GTPase signalling pathway at the level of RhoGEF. EspH directly binds the DH-PH domain in multiple RhoGEFs, which prevents their binding to Rho and thereby inhibits nucleotide exchange-mediated Rho activation. Consistently, infection of mouse macrophages with EPEC harbouring EspH attenuates phagocytosis of the bacteria as well as Fc?R-mediated phagocytosis. EspH represents the first example of targeting RhoGEFs by bacterial effectors, and our results also reveal an unprecedented mechanism used by enteric pathogens to counteract the host defence system. PMID:20300064

Dong, Na; Liu, Liping; Shao, Feng

2010-01-01

300

Lipid binding activities of flax rust AvrM and AvrL567 effectors  

PubMed Central

Effectors are pathogen-encoded proteins that are thought to facilitate infection by manipulation of host cells. Evidence showing that the effectors of some eukaryotic plant pathogens are able to interact directly with cytoplasmic host proteins indicates that translocation of these proteins into host cells is an important part of infection. Recently, we showed that the flax rust effectors AvrM and AvrL567 are able to internalize into plant cells in the absence of the pathogen. Further, N-terminal sequences that were sufficient for uptake were identified for both these proteins. In light of the possibility that the internalization of fungal and oomycete effectors may require binding to specific phospholipids, the lipid binding activities of AvrM and AvrL567 mutants with different abilities to enter cells were tested. While AvrL567 was not found to bind to phospholipids, AvrM bound strongly to phosphatidyl inositol, phosphatidyl inositol monophosphates and phosphatidyl serine. However, a fragment of AvrM sufficient to direct uptake of a fusion protein into plant cells did not bind to these phospholipids. Thus, our results do not support the role of specific binding of AvrM and AvrL567 to phospholipids for uptake into the plant cytoplasm. PMID:20855950

Gan, Pamela HP; Rafiqi, Maryam; Ellis, Jeffrey G; Jones, David A; Hardham, Adrienne R

2010-01-01

301

Ultrastructural study of Rac1 and its effectors beneath the substratum-facing membrane.  

PubMed

The cytoskeletal architecture and adhesion apparatus are tightly controlled during embryogenesis, tissue development, and carcinogenesis. The Rho family GTPases play central roles in regulation of the cytoskeleton and adhesions. Rac1, one of the Rho family GTPases, appears to be activated at the plasma membrane and exert its functions through its effectors. However, where Rac1 and its effectors function at the molecular level remains to be determined. In this study, we examined the molecular organization on the cytoplasmic surface of the substratum-facing plasma membrane, focusing on Rac1 and its effectors, IQGAP1 and Sra-1, by electron microscopy. We employed deep-etch immunoreplica methods to observe the membrane cytoskeletal architecture while determining molecular locations. Beneath the plasma membrane, Rac1 and its effectors showed similar, but distinct, destinations. Rac1 localized on the membrane and associated with the membrane cytoskeleton. IQGAP1 predominantly localized beside actin filaments and occasionally near microtubules together with Rac1. On the other hand, Sra-1 localized at actin filaments, microtubules, and the plasma membrane. Sra-1 colabeled with Rac1 was mainly found at the membrane and actin filaments. These results suggest that IQGAP1 and Sra-1 colocalize with Rac1 at distinct places, including the plasma membrane and cytoskeletal architecture, for their specific functions. PMID:18497446

Watanabe, Takashi; Wang, Shujie; Kakeno, Mai; Usukura, Jiro; Kaibuchi, Kozo

2008-01-01

302

Representation of the Speech Effectors in the Human Motor Cortex: Somatotopy or Overlap?  

ERIC Educational Resources Information Center

Somatotopy within the orofacial region of the human motor cortex has been a central concept in interpreting the results of neuroimaging and transcranial magnetic stimulation studies of normal and disordered speech. Yet, somatotopy has been challenged by studies showing overlap among the effectors within the homunculus. In order to address this…

Takai, Osamu; Brown, Steven; Liotti, Mario

2010-01-01

303

Enzymology and Ecology of the Nitrogen Cycle 189 The role of effector molecules in signal  

E-print Network

Enzymology and Ecology of the Nitrogen Cycle 189 The role of effector molecules in signal­protein interaction to control the activities of a wide range of enzymes, transcription factors and transport proteins, the great majority of which are involved in cellular nitrogen metabolism. The regulatory activities of PII

Merrick, Mike

304

Repertoire Development and the Control of Cytotoxic/Effector Function in Human ?? T Cells  

PubMed Central

T cells develop into two major populations distinguished by their T cell receptor (TCR) chains. Cells with the ?? TCR generally express CD4 or CD8 lineage markers and mostly fall into helper or cytotoxic/effector subsets. Cells expressing the alternate ?? TCR in humans generally do not express lineage markers, do not require MHC for antigen presentation, and recognize nonpeptidic antigens. We are interested in the dominant V?2V?2+ T cell subset in human peripheral blood and the control of effector function in this population. We review the literature on ?? T cell generation and repertoire selection, along with recent work on CD56 expression and defining a cytotoxic/effector lineage within the phosphoantigen-reactive V?2V?2 cells. A unique mechanism for MHC-independent repertoire selection is linked to the control of effector function that is vital to the role for ?? T cells in tumor surveillance. Better understanding of these mechanisms will improve our ability to exploit this population for tumor immunotherapy. PMID:20396597

Urban, Elizabeth M.; Chapoval, Andrei I.; Pauza, C. David

2010-01-01

305

Using effectors of Phytophthora infestans to teach pathogenesis: Our attempt to provide a more comprehensive education  

Technology Transfer Automated Retrieval System (TEKTRAN)

The topic of pathogenesis mechanisms (R/avirulence genes, effectors, and hypersensitive response) has proved challenging for students in our introductory plant pathology course. An apparent gap exists in the curriculum between this introductory course and higher level plant-microbe interaction cours...

306

A Novel End-Effector Design for Robotics in Image Guided Needle Procedures  

PubMed Central

Robotic end-effectors are being developed to facilitate image-guided minimally-invasive needle-based procedures such as tumor ablation, biopsy, thoracentesis, and blood sampling. A novel mechanical end-effector was designed to address the challenges associated with any major needle-based procedure, focusing on liver biopsy and ablation. In this end-effector embodiment, the distal end of a single articulating arm can grip needles and instruments and allow a fairly high number of degrees of freedom of movement during the complex motions associated with positioning and driving needles, as well as the periodic motions associated with breathing patterns. Tightening a cable that runs through the articulations fixes the arm in a rigid state, allowing insertion of the gripped needle. In its final form, we diagram a design that will require electro-mechanical stimulation and remote joystick control. Moreover, we discuss how cranial-caudal motion of soft tissue organs and the associated forces affect design constraints. A simulation protocol describes the use of tissue phantoms with mechanical properties in the range of hepatic tissue and the overlying abdominal wall. Finally, an in vivo protocol details the possible use of a robotic arm coupled with our end-effector in an image-guided interventional suite. Such a switchable and flexible mode for a robotic arm overcomes much of the current limitations for automated needle placements for mobile targets, subject to breathing or patient motion and the inherent risks thereof. PMID:17520618

Sun, David; Willingham, Chris; Durrani, Amir; King, Paul; Cleary, Kevin; Wood, Bradford

2008-01-01

307

Critical requirement for the Wiskott-Aldrich syndrome protein in Th2 effector function  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Wiskott-Aldrich syndrome protein (WASp) regulates actin polymerization via activation of Arp2/3 and plays a role in the dynamics of the immunological synapse. How these events influence subsequent gene expression and effector function is unclear. We studied the role of WASp in CD4+ T cell effe...

308

Course Objective 1 1a Describe the cells, products, and effector responses of the immune system  

E-print Network

, and effector responses of the immune system 2 1a Describe an immune response from are recognized, presented to the immune system, and how this influences vaccine design 7 1a drugs alter the function of the immune system 11 1a, 1b Explain the consequences

Myers, Lawrence C.

309

Relative end-effector control using Cartesian position based visual servoing  

Microsoft Academic Search

This paper presents a complete design methodology for Cartesian position based visual servo control for robots with a single camera mounted at the end-effector. Position based visual servo control requires the explicit calculation of the relative position and orientation (POSE) of the workpiece object with respect to the camera. This is accomplished using image plane measurements of a number of

William J. Wilson; Carol C. Williams Hulls; Graham S. Bell

1996-01-01

310

Evolution of RXLR-Class Effectors in the Oomycete Plant Pathogen Phytophthora ramorum  

E-print Network

and their pathogens are complex, encompassing several layers of defense and counter- defense by the plant hostEvolution of RXLR-Class Effectors in the Oomycete Plant Pathogen Phytophthora ramorum Erica M. Goss Agricultural Research Service, Corvallis, Oregon, United States of America Abstract Phytophthora plant

Grünwald, Niklaus J.

311

2009NatureAmerica,Inc.Allrightsreserved. Effector T cells control lung inflammation during  

E-print Network

©2009NatureAmerica,Inc.Allrightsreserved. Effector T cells control lung inflammation during acute in the infected lungs in large amounts--exclusively by infiltrating virus-specific Teff cells, with CD8+ Teff Teff cells exert regulatory functions--that is, they fine-tune the extent of lung inflammation

312

Two subsets of memory T lymphocytes with distinct homing potentials and effector functions  

Microsoft Academic Search

Naive T lymphocytes travel to T-cell areas of secondary lymphoid organs in search of antigen presented by dendritic cells. Once activated, they proliferate vigorously, generating effector cells that can migrate to B-cell areas or to inflamed tissues. A fraction of primed T lymphocytes persists as circulating memory cells that can confer protection and give, upon secondary challenge, a qualitatively different

Federica Sallusto; Danielle Lenig; Reinhold Förster; Martin Lipp; Antonio Lanzavecchia

1999-01-01

313

Distribution of non-LEE-encoded type 3 secretion system dependent effectors in enteropathogenic Escherichia coli  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) are important human gastroenteritis agents. The prevalence of six non-LEE genes encoding type 3 translocated effectors was investigated. The nleC, cif and nleB genes were more prevalent in typical than in atypical EPEC, although a higher diversity of genes combinations was observed in atypical EPEC. PMID:25477918

Salvador, Fábia A.; Hernandes, Rodrigo T.; Vieira, Mônica A.M.; Rockstroh, Anna C.; Gomes, Tânia A.T.

2014-01-01

314

Salmonella type III effector SopB modulates host cell exocytosis  

PubMed Central

Salmonella enterica pathogenesis is dependent on its ability to enter and replicate inside host cells. Replication occurs inside the Salmonella-containing vacuole (SCV), a vacuolar compartment that is modified by bacterial effectors secreted through the two type III secretion systems (T3SS-1 and T3SS-2). Type III effectors interact with the host cell endocytic pathway to aid replication. We investigated whether Salmonella effector proteins may also interact with the host's exocytic pathway. A secreted alkaline phosphatase (SEAP) assay indicated three Salmonella effectors inhibited the secretory pathway, although only Salmonella outer protein B (SopB) was confirmed to block exocytosis using a vesicular stomatitis virus glycoprotein-green fluorescent protein (VSVG-GFP) transport assay. The 4-phosphatase activity of SopB was crucial to its effect on exocytosis. The interaction with the secretory pathway could potentially be important for providing replicating Salmonella with nutrients, contributing membrane material necessary for SCV biogenesis, altering antibacterial peptide/protein secretion or manipulating cell surface proteins important in the host response to infection.

Perrett, Charlotte A; Zhou, Daoguo

2013-01-01

315

Actin Cytoskeleton Manipulation by Effector Proteins Secreted by Diarrheagenic Escherichia coli Pathotypes  

PubMed Central

The actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. Disruption of the epithelial barrier coincides with alterations of the actin cytoskeleton in several disease states. These disruptions primarily affect the paracellular space, which is normally regulated by tight junctions. Thereby, the actin cytoskeleton is a common and recurring target of bacterial virulence factors. In order to manipulate the actin cytoskeleton, bacteria secrete and inject toxins and effectors to hijack the host cell machinery, which interferes with host-cell pathways and with a number of actin binding proteins. An interesting model to study actin manipulation by bacterial effectors is Escherichia coli since due to its genome plasticity it has acquired diverse genetic mobile elements, which allow having different E. coli varieties in one bacterial species. These E. coli pathotypes, including intracellular and extracellular bacteria, interact with epithelial cells, and their interactions depend on a specific combination of virulence factors. In this paper we focus on E. coli effectors that mimic host cell proteins to manipulate the actin cytoskeleton. The study of bacterial effector-cytoskeleton interaction will contribute not only to the comprehension of the molecular causes of infectious diseases but also to increase our knowledge of cell biology. PMID:23509714

Navarro-Garcia, Fernando; Serapio-Palacios, Antonio; Ugalde-Silva, Paul; Tapia-Pastrana, Gabriela; Chavez-Dueñas, Lucia

2013-01-01

316

Sustained effector function of IL-12/15/18-preactivated NK cells against established tumors.  

PubMed

Natural killer cell (NK cell)-based immunotherapy of cancer is hampered by the transient effector function of NK cells. Recently, mouse IL-12/15/18-preactivated NK cells were shown to persist with sustained effector function in vivo. Our study investigated the antitumor activity of such NK cells. A single injection of syngeneic IL-12/15/18-preactivated NK cells, but neither naive nor IL-15- or IL-2-pretreated NK cells, combined with irradiation substantially reduced growth of established mouse tumors. Radiation therapy (RT) was essential for the antitumor activity of transferred NK cells. IL-12/15/18-preactivated NK cells expressed high levels of IL-2R? (CD25), and their rapid in vivo proliferation depended on IL-2 produced by CD4+ T cells. IL-12/15/18-preactivated NK cells accumulated in the tumor tissue and persisted at high cell numbers with potent effector function that required the presence of CD4+ T cells. RT greatly increased numbers and function of transferred NK cells. Human IL-12/15/18-preactivated NK cells also displayed sustained effector function in vitro. Our study provides a better understanding for the rational design of immunotherapies of cancer that incorporate NK cells. Moreover, our results reveal an essential role of CD4+ T cell help for sustained antitumor activity by NK cells linking adaptive and innate immunity. PMID:23209317

Ni, Jing; Miller, Matthias; Stojanovic, Ana; Garbi, Natalio; Cerwenka, Adelheid

2012-12-17

317

Peroxiredoxin II Regulates Effector and Secondary Memory CD8+ T Cell Responses  

PubMed Central

Reactive oxygen intermediates (ROI) generated in response to receptor stimulation play an important role in cellular responses. However, the effect of increased H2O2 on an antigen-specific CD8+ T cell response was unknown. Following T cell receptor (TCR) stimulation, the expression and oxidation of peroxiredoxin II (PrdxII), a critical antioxidant enzyme, increased in CD8+ T cells. Deletion of PrdxII increased ROI, S phase entry, division, and death during in vitro division. During primary acute viral and bacterial infection, the number of effector CD8+ T cells in PrdxII-deficient mice was increased, while the number of memory cells were similar to those of the wild-type cells. Adoptive transfer of P14 TCR transgenic cells demonstrated that the increased expansion of effector cells was T cell autonomous. After rechallenge, effector CD8+ T cells in mutant animals were more skewed to memory phenotype than cells from wild-type mice, resulting in a larger secondary memory CD8+ T cell pool. During chronic viral infection, increased antigen-specific CD8+ T cells accumulated in the spleens of PrdxII mutant mice, causing mortality. These results demonstrate that PrdxII controls effector CD8+ T cell expansion, secondary memory generation, and immunopathology. PMID:23055551

Michalek, Ryan D.; Crump, Katie E.; Weant, Ashley E.; Hiltbold, Elizabeth M.; Juneau, Daniel G.; Moon, Eun-Yi; Yu, Dae-Yeul; Poole, Leslie B.

2012-01-01

318

Mutualistic Co-evolution of Type III Effector Genes in Sinorhizobium fredii and Bradyrhizobium japonicum  

E-print Network

Mutualistic Co-evolution of Type III Effector Genes in Sinorhizobium fredii and Bradyrhizobium paradigms have been proposed to model the molecular co-evolution of microbial mutualists and their eukaryotic hosts. In one, mutualist and host exhibit an antagonistic arms race and each partner evolves

Sachs, Joel

319

Advances in the assessment and control of the effector functions of therapeutic antibodies  

Microsoft Academic Search

The Fc (crystallizable fragment) region of therapeutic antibodies can have an important role in their safety and efficacy. Although much is known about the structure–activity relationship of antibodies and the factors that influence Fc effector functions, a process has not yet been defined to clearly delineate how Fc functionality should be assessed and controlled during antibody development and manufacturing. In

An Song; Svetlana Bergelson; Thomas Arroll; Bhavin Parekh; Kimberly May; Shan Chung; Robert Strouse; Anthony Mire-Sluis; Mark Schenerman; Xu-Rong Jiang

2011-01-01

320

Global diversity and distribution of three necrotrophic effectors in Phaeosphaeria nodorum and related species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Population genetic and phylogenetic studies showed that P. nodorum is a member of a species-complex that likely shares its center of origin with wheat. We examined the evolutionary history of three known necrotrophic effectors (NEs) produced by Phaeosphaeria nodorum and compared it to neutral loci. ...

321

Human reinforcement learning subdivides structured action spaces by learning effector-specific values.  

PubMed

Humans and animals are endowed with a large number of effectors. Although this enables great behavioral flexibility, it presents an equally formidable reinforcement learning problem of discovering which actions are most valuable because of the high dimensionality of the action space. An unresolved question is how neural systems for reinforcement learning-such as prediction error signals for action valuation associated with dopamine and the striatum-can cope with this "curse of dimensionality." We propose a reinforcement learning framework that allows for learned action valuations to be decomposed into effector-specific components when appropriate to a task, and test it by studying to what extent human behavior and blood oxygen level-dependent (BOLD) activity can exploit such a decomposition in a multieffector choice task. Subjects made simultaneous decisions with their left and right hands and received separate reward feedback for each hand movement. We found that choice behavior was better described by a learning model that decomposed the values of bimanual movements into separate values for each effector, rather than a traditional model that treated the bimanual actions as unitary with a single value. A decomposition of value into effector-specific components was also observed in value-related BOLD signaling, in the form of lateralized biases in striatal correlates of prediction error and anticipatory value correlates in the intraparietal sulcus. These results suggest that the human brain can use decomposed value representations to "divide and conquer" reinforcement learning over high-dimensional action spaces. PMID:19864565

Gershman, Samuel J; Pesaran, Bijan; Daw, Nathaniel D

2009-10-28

322

Interleukin-21 suppresses the differentiation and functions of T helper 2 cells.  

PubMed

T helper (Th) 2 cells, which produce IL-4, IL-5, and IL-13, control immunity to all forms of allergic inflammatory responses. IL-21 reduces allergic symptoms in murine models and inhibits IL-4-induced IgE secretion by B cells. However, whether or not IL-21 directly affects Th2 cells which leads to reduced allergic symptoms is unclear. In this study, we investigated the effects of IL-21 on the differentiation and effector functions of Th2 cells. We found that IL-21 reduced the number of differentiated Th2 cells and these Th2 cells showed a diminished Th2 cytokine production. IL-21 suppressed Th2 cytokine production of already polarized Th2 cells by downregulation of transcription factor GATA-3. IL-21 also induced apoptosis of Th2 cells with decreased anti-apoptotic factor Bcl-2. Intranasal administration of IL-21 at the beginning of OVA sensitization or before OVA challenge decreased Th2 cytokines in the bronchoalveolar lavage fluid (BALF) of OVA/alum immunized allergic mice. In addition, the inhibitory effects of IL-21 on Th2 effector functions can also be found in allergic patients. Our results demonstrate that IL-21 suppresses the development of Th2 cells and functions of polarized Th2 cells. Hence, the administration of IL-21 may be considered for use as a preventive and therapeutic approach when dealing with Th2 mediated allergic diseases. This article is protected by copyright. All rights reserved. PMID:25351608

Lin, Pin-Yi; Jen, Hsiao-Yu; Chiang, Bor-Luen; Sheu, Fuu; Chuang, Ya-Hui

2014-10-28

323

Neutrophils but not eosinophils are involved in growth suppression of IL-4-secreting tumors.  

PubMed

Local expression of IL-4 by gene-modified tumor cells increases their immunogenicity by inducing an inflammatory response that is dominated by eosinophils. Eosinophils have been implicated as antitumor effector cells because the application of a granulocyte-depleting Ab inhibited rejection of IL-4 transfected tumors. This Ab did not discriminate between eosinophils and neutrophils and, therefore, this experiment could not exclude neutrophils as primary effector cells, whereas eosinophils were innocent bystander cells in IL-4 transfected tumors. We analyzed tumor growth suppression and granulocyte infiltration in IL-5-deficient (IL-5(-/-)) mice that had a deficiency of eosinophils, using two tumor lines (B16-F10 and MCA205) transfected to secrete IL-4. IL-4-expressing tumors were at least as efficiently rejected in IL-5(-/-) mice as in wild-type mice, despite an almost complete absence of tumor-infiltrating eosinophils. However, neutrophils were present in undiminished amounts and their depletion partially restored tumor growth. Furthermore, the growth of IL-5-secreting tumors was not impaired in either wild-type or IL-5(-/-) mice, even though it induced eosinophilia in both mouse strains. These findings demonstrate that eosinophils can be induced in IL-5(-/-) mice by exogenous IL-5 and argue against a compensatory effect of neutrophils in the absence of eosinophils. We conclude that 1) infiltration of IL-4 transfected tumors by eosinophils is completely IL-5 dependent, 2) eosinophils have no tumoricidal activity, and 3) neutrophils are responsible, at least in part, for tumor suppression. PMID:9551990

Noffz, G; Qin, Z; Kopf, M; Blankenstein, T

1998-01-01

324

Chemical Genetics Reveals Bacterial and Host Cell Functions Critical for Type IV Effector Translocation by Legionella pneumophila  

PubMed Central

Delivery of effector proteins is a process widely used by bacterial pathogens to subvert host cell functions and cause disease. Effector delivery is achieved by elaborate injection devices and can often be triggered by environmental stimuli. However, effector export by the L. pneumophila Icm/Dot Type IVB secretion system cannot be detected until the bacterium encounters a target host cell. We used chemical genetics, a perturbation strategy that utilizes small molecule inhibitors, to determine the mechanisms critical for L. pneumophila Icm/Dot activity. From a collection of more than 2,500 annotated molecules we identified specific inhibitors of effector translocation. We found that L. pneumophila effector translocation in macrophages requires host cell factors known to be involved in phagocytosis such as phosphoinositide 3-kinases, actin and tubulin. Moreover, we found that L. pneumophila phagocytosis and effector translocation also specifically require the receptor protein tyrosine phosphate phosphatases CD45 and CD148. We further show that phagocytosis is required to trigger effector delivery unless intimate contact between the bacteria and the host is artificially generated. In addition, real-time analysis of effector translocation suggests that effector export is rate-limited by phagocytosis. We propose a model in which L. pneumophila utilizes phagocytosis to initiate an intimate contact event required for the translocation of pre-synthesized effector molecules. We discuss the need for host cell participation in the initial step of the infection and its implications in the L. pneumophila lifestyle. Chemical genetic screening provides a novel approach to probe the host cell functions and factors involved in host–pathogen interactions. PMID:19578436

Charpentier, Xavier; Gabay, Joëlle E.; Reyes, Moraima; Zhu, Jing W.; Weiss, Arthur; Shuman, Howard A.

2009-01-01

325

Physiologically based kinetic model of effector cell biodistribution in mammals: implications for adoptive immunotherapy.  

PubMed

The goal of the present investigation was to develop a physiologically based kinetic model to describe the biodistribution of immunologically active effector cells in normal and neoplastic tissues of mammals based on the current understanding of lymphocyte trafficking pathways and signals. The model was used to extrapolate biodistribution among different animal species and to identify differences among different effector populations and between intra-arterial and systemic injections. Most importantly, the model was used to discern critical parameters for improving the delivery of effector cells. In the model, the mammalian body was divided into 12 organ compartments, interconnected in anatomic fashion. Each compartment was characterized by blood flow rate, organ volume and lymphatic flow rate, and other physiological and immunological parameters. The resulting set of 45 differential equations was solved numerically. The model was used to simulate the following biodistribution data: (a) nonactivated T lymphocytes in rats; (b) interleukin 2-activated tumor-infiltrating lymphocytes in humans; (c) nonactivated natural killer (NK) cells in rats; and (d) interleukin 2-activated adherent NK cells in mice. Comparisons between simulations and data demonstrated the feasibility of the model and the scaling scheme. The similarities as well as differences in biodistribution of different lymphocyte populations were revealed as results of their trafficking properties. The importance of lymphocyte infiltration from surrounding normal tissues into tumor tissue was found to depend on lymphocyte migration rate, tumor size, and host organ. The study confirmed that treatment with effector cells has not been as impressive as originally promised, due, in part, to the biodistribution problems. The model simulations demonstrated that low effector concentrations in the systemic circulation greatly limited their delivery to tumor. This was due to high retention in normal tissues, especially in the lung. Reducing normal tissue retention through decreasing attachment rate or adhesion site density in the lung by 50% could increase the tumor uptake by approximately 40% for tumor-infiltrating lymphocytes and by approximately 60% for adherent NK cells. Our analysis suggested the following strategies to improve effector cell delivery to tumor: (a) bypassing the initial lung entrapment with administration to the arterial supply of tumor; (b) reducing normal tissue retention using effector cells with high deformability or blocking lymphocyte adhesion to normal vessels; and (c) enhancing tumor-specific capture and arrest by modifying the tumor microenvironment. PMID:8706023

Zhu, H; Melder, R J; Baxter, L T; Jain, R K

1996-08-15

326

The N-terminal region of Pseudomonas type III effector AvrPtoB elicits Pto-dependent immunity and has two  

E-print Network

with either of the sequence-dissimilar type III effector proteins AvrPto or AvrPtoB (HopAB2) from Pseudo cell death, guard hypothesis, type III effectors, structural biology. Introduction Pseudomonas syringae

Sheen, Jen

327

Resequencing and Comparative Genomics of Stagonospora nodorum: Sectional Gene Absence and Effector Discovery  

PubMed Central

Stagonospora nodorum is an important wheat (Triticum aestivum) pathogen in many parts of the world, causing major yield losses. It was the first species in the large fungal Dothideomycete class to be genome sequenced. The reference genome sequence (SN15) has been instrumental in the discovery of genes encoding necrotrophic effectors that induce disease symptoms in specific host genotypes. Here we present the genome sequence of two further S. nodorum strains (Sn4 and Sn79) that differ in their effector repertoire from the reference. Sn79 is avirulent on wheat and produces no apparent effectors when infiltrated onto many cultivars and mapping population parents. Sn4 is pathogenic on wheat and has virulences not found in SN15. The new strains, sequenced with short-read Illumina chemistry, are compared with SN15 by a combination of mapping and de novo assembly approaches. Each of the genomes contains a large number of strain-specific genes, many of which have no meaningful similarity to any known gene. Large contiguous sections of the reference genome are absent in the two newly sequenced strains. We refer to these differences as “sectional gene absences.” The presence of genes in pathogenic strains and absence in Sn79 is added to computationally predicted properties of known proteins to produce a list of likely effector candidates. Transposon insertion was observed in the mitochondrial genomes of virulent strains where the avirulent strain retained the likely ancestral sequence. The study suggests that short-read enabled comparative genomics is an effective way to both identify new S. nodorum effector candidates and to illuminate evolutionary processes in this species. PMID:23589517

Syme, Robert Andrew; Hane, James K.; Friesen, Timothy L.; Oliver, Richard P.

2013-01-01

328

The pinealocyte forming receptor and effector endings: immunoelectron microscopy and calcium histochemistry.  

PubMed

The pinealocytes--the main cellular elements of the pineal organ--are polarized, displaying a (photo)receptor and an axonic effector cell pole. The receptor endings are of two main types: they bear rod-type or cone-type outer segments characterized by the presence of immunoreactive opsin-, S-antigen- and vitamin A-binding sites. The effector pole may form ribbon-containing synapses on the secondary pineal neurons, and/or neurohormonal terminals on the basal lamina of the pineal nervous tissue. Applying potassium pyroantimonate (PPA) to electron-microscopic histochemistry, we found in the frog that both effector terminals and photoreceptor outer segments contained a large amount of Ca-pyroantimonate deposit similar to retinal cones and rods. Rods and rod-like pinealocytes contained more deposits than cones. The higher concentration of calcium on the cell membranes of dark pinealocytes in the rat may be connected with their rod-like character. In the frog, a high amount of calcium seemed to be concentrated in the photoreceptor effector terminals, especially around their synaptic ribbons, and in myeloid bodies of the pineal ependyma and retinal pigment epithelium. Calcium was richly found in or around corpora arenacea in the human and rat pineal. It is suggested that the formation of concrements may be connected with the high demand of Ca-exchange of pinealocytes for their receptor and effector membrane functions. In the rat, lymphocytes were found to migrate through the wall of the vena magna of Galen and to closely contact pinealocytes, presumably to receive immunological information as an additional pineal output. PMID:2510798

Vigh, B; Vigh-Teichmann, I

1989-01-01

329

The suppressive effects of ultraviolet radiation on immunity in the skin and internal organs: implications for autoimmunity.  

PubMed

Low doses of sunlight that can be received during normal daily activities suppress immunity in humans. Both ultraviolet (UV) B (290-320 nm) and UVA (320-400 nm) are immunosuppressive. The wavelength dependence in humans shows distinct non-overlapping immunosuppressive peaks of solar effectiveness centred at 310 nm UVB and 370 nm UVA. In murine models of systemic immunosuppression low dose UV inhibits expansion of effector T cells in skin-draining lymph nodes, and retention of dermal effector memory CD8T cells at sites of antigen challenge. In addition to suppressing skin immunity, UV inhibits immunity in internal organs, including activation of CD8 T cells and cytotoxic T cell activity in the spleen, and memory T cell activation in the spleen and bone marrow. Neither of the chromophores responsible for UV suppression of skin immunity, DNA damage and urocanic acid, nor reactive oxygen species are involved in regulation of CD8 T cells in internal organs. Thus UVB impedes the activation and cytotoxicity of antigen-specific T cells in internal organs by mechanisms independent of suppression of skin immunity. These deleterious effects of low dose UV on skin immunity are likely to contribute to skin cancer, however UV suppression of immunity in internal organs may protect from autoimmunity. Epidemiological evidence suggests that sunlight protects from some autoimmune diseases directed towards internal organs. As UV suppression of skin and internal organ immunity appear to occur via different mechanisms, it may be possible to protect skin immunity and therefore reduce skin cancer incidence without preventing UV from reducing autoimmunity in internal organs. PMID:22277701

Halliday, Gary M; Damian, Diona L; Rana, Sabita; Byrne, Scott N

2012-06-01

330

Meta-analytic approach to the accurate prediction of secreted virulence effectors in gram-negative bacteria  

PubMed Central

Background Many pathogens use a type III secretion system to translocate virulence proteins (called effectors) in order to adapt to the host environment. To date, many prediction tools for effector identification have been developed. However, these tools are insufficiently accurate for producing a list of putative effectors that can be applied directly for labor-intensive experimental verification. This also suggests that important features of effectors have yet to be fully characterized. Results In this study, we have constructed an accurate approach to predicting secreted virulence effectors from Gram-negative bacteria. This consists of a support vector machine-based discriminant analysis followed by a simple criteria-based filtering. The accuracy was assessed by estimating the average number of true positives in the top-20 ranking in the genome-wide screening. In the validation, 10 sets of 20 training and 20 testing examples were randomly selected from 40 known effectors of Salmonella enterica serovar Typhimurium LT2. On average, the SVM portion of our system predicted 9.7 true positives from 20 testing examples in the top-20 of the prediction. Removal of the N-terminal instability, codon adaptation index and ProtParam indices decreased the score to 7.6, 8.9 and 7.9, respectively. These discrimination features suggested that the following characteristics of effectors had been uncovered: unstable N-terminus, non-optimal codon usage, hydrophilic, and less aliphathic. The secondary filtering process represented by coexpression analysis and domain distribution analysis further refined the average true positive counts to 12.3. We further confirmed that our system can correctly predict known effectors of P. syringae DC3000, strongly indicating its feasibility. Conclusions We have successfully developed an accurate prediction system for screening effectors on a genome-wide scale. We confirmed the accuracy of our system by external validation using known effectors of Salmonella and obtained the accurate list of putative effectors of the organism. The level of accuracy was sufficient to yield candidates for gene-directed experimental verification. Furthermore, new features of effectors were revealed: non-optimal codon usage and instability of the N-terminal region. From these findings, a new working hypothesis is proposed regarding mechanisms controlling the translocation of virulence effectors and determining the substrate specificity encoded in the secretion system. PMID:22078363

2011-01-01

331

Hepatocyte Growth Factor Is a Downstream Effector that Mediates the Antifibrotic Action of Peroxisome Proliferator–Activated Receptor-? Agonists  

PubMed Central

Peroxisome proliferator–activated receptor-? (PPAR-?) is a ligand-dependent transcription factor that plays an important role in the regulation of insulin sensitivity and lipid metabolism. Evidence shows that PPAR-? agonists also ameliorate renal fibrotic lesions in both diabetic nephropathy and nondiabetic chronic kidney disease. However, little is known about the mechanism underlying their antifibrotic action. This study demonstrated that PPAR-? agonists could exert their actions by inducing antifibrotic hepatocyte growth factor (HGF) expression. Incubation of mesangial cells with natural or synthetic PPAR-? agonists 15-deoxy-?12,14-prostaglandin J2 (15d-PGJ2) or troglitazone and ciglitazone suppressed TGF-?1–mediated ?-smooth muscle actin, fibronectin, and plasminogen activator inhibitor-1 expression. PPAR-? agonists also induced HGF mRNA expression and protein secretion. Transfection studies revealed that 15d-PGJ2 stimulated HGF gene promoter activity, which was dependent on the presence of a novel peroxisome proliferator response element. Treatment of mesangial cells with 15d-PGJ2 induced the binding of PPAR-? to the peroxisome proliferator response element in the HGF promoter region. PPAR-? agonists also activated c-met receptor tyrosine phosphorylation, induced Smad transcriptional co-repressor TG-interacting factor expression, and blocked TGF-?/Smad-mediated gene transcription in mesangial cells. Furthermore, ablation of c-met receptor through the LoxP-Cre system in mesangial cells abolished the antifibrotic effect of 15d-PGJ2. PPAR-? activation also induced HGF expression in renal interstitial fibroblasts and repressed TGF-?1–mediated myofibroblast activation. Both HGF and 15d-PGJ2 attenuated Smad nuclear translocation in response to TGF-?1 stimulation in renal fibroblasts. Together, these findings suggest that HGF may act as a downstream effector that mediates the antifibrotic action of PPAR-? agonists. PMID:16291834

Li, Yingjian; Wen, Xiaoyan; Spataro, Bradley C.; Hu, Kebin; Dai, Chunsun; Liu, Youhua

2007-01-01

332

Phytoplasma effector SAP54 hijacks plant reproduction by degrading MADS-box proteins and promotes insect colonization in a RAD23-dependent manner.  

PubMed

Pathogens that rely upon multiple hosts to complete their life cycles often modify behavior and development of these hosts to coerce them into improving pathogen fitness. However, few studies describe mechanisms underlying host coercion. In this study, we elucidate the mechanism by which an insect-transmitted pathogen of plants alters floral development to convert flowers into vegetative tissues. We find that phytoplasma produce a novel effector protein (SAP54) that interacts with members of the MADS-domain transcription factor (MTF) family, including key regulators SEPALLATA3 and APETALA1, that occupy central positions in the regulation of floral development. SAP54 mediates degradation of MTFs by interacting with proteins of the RADIATION SENSITIVE23 (RAD23) family, eukaryotic proteins that shuttle substrates to the proteasome. Arabidopsis rad23 mutants do not show conversion of flowers into leaf-like tissues in the presence of SAP54 and during phytoplasma infection, emphasizing the importance of RAD23 to the activity of SAP54. Remarkably, plants with SAP54-induced leaf-like flowers are more attractive for colonization by phytoplasma leafhopper vectors and this colonization preference is dependent on RAD23. An effector that targets and suppresses flowering while simultaneously promoting insect herbivore colonization is unprecedented. Moreover, RAD23 proteins have, to our knowledge, no known roles in flower development, nor plant defence mechanisms against insects. Thus SAP54 generates a short circuit between two key pathways of the host to alter development, resulting in sterile plants, and promotes attractiveness of these plants to leafhopper vectors helping the obligate phytoplasmas reproduce and propagate (zombie plants). PMID:24714165

MacLean, Allyson M; Orlovskis, Zigmunds; Kowitwanich, Krissana; Zdziarska, Anna M; Angenent, Gerco C; Immink, Richard G H; Hogenhout, Saskia A

2014-04-01

333

Phytoplasma Effector SAP54 Hijacks Plant Reproduction by Degrading MADS-box Proteins and Promotes Insect Colonization in a RAD23-Dependent Manner  

PubMed Central

Pathogens that rely upon multiple hosts to complete their life cycles often modify behavior and development of these hosts to coerce them into improving pathogen fitness. However, few studies describe mechanisms underlying host coercion. In this study, we elucidate the mechanism by which an insect-transmitted pathogen of plants alters floral development to convert flowers into vegetative tissues. We find that phytoplasma produce a novel effector protein (SAP54) that interacts with members of the MADS-domain transcription factor (MTF) family, including key regulators SEPALLATA3 and APETALA1, that occupy central positions in the regulation of floral development. SAP54 mediates degradation of MTFs by interacting with proteins of the RADIATION SENSITIVE23 (RAD23) family, eukaryotic proteins that shuttle substrates to the proteasome. Arabidopsis rad23 mutants do not show conversion of flowers into leaf-like tissues in the presence of SAP54 and during phytoplasma infection, emphasizing the importance of RAD23 to the activity of SAP54. Remarkably, plants with SAP54-induced leaf-like flowers are more attractive for colonization by phytoplasma leafhopper vectors and this colonization preference is dependent on RAD23. An effector that targets and suppresses flowering while simultaneously promoting insect herbivore colonization is unprecedented. Moreover, RAD23 proteins have, to our knowledge, no known roles in flower development, nor plant defence mechanisms against insects. Thus SAP54 generates a short circuit between two key pathways of the host to alter development, resulting in sterile plants, and promotes attractiveness of these plants to leafhopper vectors helping the obligate phytoplasmas reproduce and propagate (zombie plants). PMID:24714165

MacLean, Allyson M.; Orlovskis, Zigmunds; Kowitwanich, Krissana; Zdziarska, Anna M.; Angenent, Gerco C.; Immink, Richard G. H.; Hogenhout, Saskia A.

2014-01-01

334

Diverse evolutionary mechanisms shape the type III effector virulence factor repertoire in the plant pathogen Pseudomonas syringae.  

PubMed Central

Many gram-negative pathogenic bacteria directly translocate effector proteins into eukaryotic host cells via type III delivery systems. Type III effector proteins are determinants of virulence on susceptible plant hosts; they are also the proteins that trigger specific disease resistance in resistant plant hosts. Evolution of type III effectors is dominated by competing forces: the likely requirement for conservation of virulence function, the avoidance of host defenses, and possible adaptation to new hosts. To understand the evolutionary history of type III effectors in Pseudomonas syringae, we searched for homologs to 44 known or candidate P. syringae type III effectors and two effector chaperones. We examined 24 gene families for distribution among bacterial species, amino acid sequence diversity, and features indicative of horizontal transfer. We assessed the role of diversifying and purifying selection in the evolution of these gene families. While some P. syringae type III effectors were acquired recently, others have evolved predominantly by descent. The majority of codons in most of these genes were subjected to purifying selection, suggesting selective pressure to maintain presumed virulence function. However, members of 7 families had domains subject to diversifying selection. PMID:15280247

Rohmer, Laurence; Guttman, David S; Dangl, Jeffery L

2004-01-01

335

Reprogrammed FoxP3+ T Regulatory Cells Become IL-17+ Antigen-Specific Autoimmune Effectors in Vitro and In Vivo1  

PubMed Central

This is an author-produced version of a manuscript accepted for publication in The Journal of Immunology (The JI). The American Association of Immunologists, Inc. (AAI), the publisher of The JI, holds the copyright to this manuscript. This version of the manuscript has not yet been copyedited or subjected to editorial proofreading by The JI; hence, it may differ from the final version published in The JI (online and in print). AAI (The JI) is not liable for errors or omissions in this author-produced version of the manuscript or in any version derived from it by the U.S. National Institutes of Health or any other third party. The final, citable version of record can be found at www.jimmunol.org Lymphocyte differentiation from naïve CD4+ T cells into mature Th1, Th2, Th17, or T regulatory cell (Treg) phenotypes has been considered end stage in character. Here we demonstrate that DC activated with a novel immune modulator B7-DC XAb (DCXAb) can reprogram Tregs into T effector cells. Downregulation of FoxP3 expression after either in vitro or in vivo Treg:DCXAb interaction is antigen specific, IL-6-dependent, and results in the functional reprogramming of the mature T cell phenotype. The reprogrammed Tregs cease to express IL-10 and TGF?, fail to suppress T cell responses, and gain the ability to produce IFN?, IL-17, and TNF?. The ability of IL-6+ DCXAb and the inability of IL-6-/- DCXAb vaccines to protect animals from lethal melanoma suggest that exogenously modulated DC can reprogram host Tregs. In support of this hypothesis and as a test for antigen specificity, transfer of DCXAb into RIP-OVA mice causes a break in immune tolerance, inducing diabetes. Conversely, adoptive transfer of reprogrammed Tregs but not similarly treated CD25- T cells into naïve RIP-OVA mice is also sufficient to cause autoimmune diabetes. Yet, treatment of normal mice with B7-DC XAb fails to elicit generalized autoimmunity. The finding that mature Tregs can be reprogrammed into competent effector cells provides new insights into the plasticity of T cell lineage, underscores the importance of DC:T cell interactions in balancing immunity with tolerance, points to Tregs as a reservoir of autoimmune effectors, and defines a new approach for breaking tolerance to self antigens as a strategy for cancer immunotherapy. PMID:18713984

Radhakrishnan, Suresh; Cabrera, Rosalyn A.; Schenk, Erin L.; Nava-Parada, Pilar; Bell, Michael P.; Van Keulen, Virginia P.; Marler, Ronald J.; Felts, Sara J.; Pease, Larry R.

2008-01-01

336

Augmented Followed by Suppressed Levels of Natural Cell-Mediated Cytotoxicity in Mice Infected with Toxoplasma gondii  

PubMed Central

The cytotoxic activity of effector cells from mice infected with Toxoplasma gondii was tested in a 4- to 5-hr 51Cr release assay, using RL 0001000 0011100 0101010 0001000 0001000 0011100 0100010 1000001 1000001 1000001 0100010 0011100 1 and YAC-1 target cells. They showed enhanced cytotoxicity with a peak on the 3rd day postinfection followed by suppression with a peak on the 12th day. The cytotoxicity seemed to be exhibited by natural killer (NK) cells because: (i) pretreatment of the effector cells with antiasialo GM1 or antiasialo GM2 plus complement abolished the cytotoxic activity; (ii) the altered cytotoxicity levels were also induced in nude mice; and (iii) the activity was elicited by nonadherent-nonphagocytic cells. The alteration occurred simultaneously in various lymphoid organs with a similar profile. Neither spleen nor bone marrow cells of 12-day-postinfected mice inhibited NK activity of uninfected mice. Culture fluids of the infected mouse spleen and bone marrow cells did not affect the normal mouse NK activity. The proportion of effector cells capable of binding to target cells was constant during the infection. There was no positive correlation between NK activity and serum interferon level; i.e., interferon was detected in the serum of 12-day-postinfected mice but not in that of 3-day-postinfected or uninfected mice. Passively administered interferon or polyinosinic-polycytidylic acid could not restore the suppressed NK activity of 12-day-postinfected mice. Moreover, in vitro treatment of spleen cells from 12-day-postinfected mice with interferon failed to restore the suppressed NK activity. These results suggested that after toxoplasma infection, defective sensitivity to interferon was induced in NK precursor cells, and differentiation to functionally active NK cells might be blocked. PMID:6177634

Kamiyama, Tsuneo; Hagiwara, Toshikatsu

1982-01-01

337

Tailored Immune Responses: Novel Effector Helper T Cell Subsets in Protective Immunity  

PubMed Central

Differentiation of naïve CD4+ cells into functionally distinct effector helper T cell subsets, characterised by distinct “cytokine signatures,” is a cardinal strategy employed by the mammalian immune system to efficiently deal with the rapidly evolving array of pathogenic microorganisms encountered by the host. Since the TH1/TH2 paradigm was first described by Mosmann and Coffman, research in the field of helper T cell biology has grown exponentially with seven functionally unique subsets having now been described. In this review, recent insights into the molecular mechanisms that govern differentiation and function of effector helper T cell subsets will be discussed in the context of microbial infections, with a focus on how these different helper T cell subsets orchestrate immune responses tailored to combat the nature of the pathogenic threat encountered. PMID:24586147

Kara, Ervin E.; Comerford, Iain; Fenix, Kevin A.; Bastow, Cameron R.; Gregor, Carly E.; McKenzie, Duncan R.; McColl, Shaun R.

2014-01-01

338

Structure of a Filament-Like Actin Trimer Bound to the Bacterial Effector VopL  

PubMed Central

Summary Bacterial pathogens use secreted effector proteins to subvert host-cell defenses. VopL is an effector protein from Vibrio parahaemolyticus that nucleates actin filaments. VopL consists of a VopL C-terminal Domain (VCD) and a tandem array of three WASP homology 2 (WH2) motifs. Here we report the crystal structure of the VCD dimer bound to actin. The VCD binds three actin monomers in a spatial arrangement close to that in the canonical actin filament. In this configuration each actin can readily accommodate a WH2 motif. The data suggest a mechanism of nucleation wherein VopL creates filament-like structures, organized by the VCD and delivered by the WH2 array, that can template addition of new monomers. Similarities with Arp2/3 complex and formin proteins suggest that organization of monomers into filament-like structures is a general and central feature of actin nucleation. PMID:24120140

Zahm, Jacob A.; Padrick, Shae B.; Chen, Zhucheng; Pak, Chi W.; Yunus, Ali A.; Henry, Lisa; Tomchick, Diana R.; Chen, Zhe; Rosen, Michael K.

2013-01-01

339

Ubiquitylome analysis identifies dysregulation of effector substrates in SPOP-mutant prostate cancer  

PubMed Central

Cancer genome characterization has revealed driver mutations in genes that govern ubiquitylation; however, the mechanisms by which these alterations promote tumorigenesis remain incompletely characterized. Here, we analyzed changes in the ubiquitin landscape induced by prostate cancer-associated mutations of SPOP, an E3 ubiquitin ligase substrate binding protein. SPOP mutants impaired ubiquitylation of a subset of proteins in a dominant-negative fashion. Of these, DEK and TRIM24 emerged as effector substrates consistently up-regulated by SPOP mutants. We highlight DEK as a SPOP substrate that exhibited decreases in ubiquitylation and proteasomal degradation resulting from heteromeric complexes of wild-type and mutant SPOP protein. DEK stabilization promoted prostate epithelial cell invasion, implicating DEK as an oncogenic effector. More generally, these results provide a framework to decipher tumorigenic mechanisms linked to dysregulated ubiquitylation. PMID:25278611

Svinkina, Tanya; Baca, Sylvan C.; Pop, Marius; Wild, Peter J.; Blattner, Mirjam; Groner, Anna C.; Rubin, Mark A.; Moch, Holger; Prive, Gilbert G.; Carr, Steven A.; Garraway, Levi A.

2014-01-01

340

Probing the initiation and effector phases of the somatic piRNA pathway in Drosophila  

PubMed Central

Combining RNAi in cultured cells and analysis of mutant animals, we probed the roles of known Piwi-interacting RNA (piRNA) pathway components in the initiation and effector phases of transposon silencing. Squash associated physically with Piwi, and reductions in its expression led to modest transposon derepression without effects on piRNAs, consistent with an effector role. Alterations in Zucchini or Armitage reduced both Piwi protein and piRNAs, indicating functions in the formation of a stable Piwi RISC (RNA-induced silencing complex). Notably, loss of Zucchini or mutations within its catalytic domain led to accumulation of unprocessed precursor transcripts from flamenco, consistent with a role for this putative nuclease in piRNA biogenesis. PMID:20966049

Haase, Astrid D.; Fenoglio, Silvia; Muerdter, Felix; Guzzardo, Paloma M.; Czech, Benjamin; Pappin, Darryl J.; Chen, Caifu; Gordon, Assaf; Hannon, Gregory J.

2010-01-01

341

Representation of the speech effectors in the human motor cortex: somatotopy or overlap?  

PubMed

Somatotopy within the orofacial region of the human motor cortex has been a central concept in interpreting the results of neuroimaging and transcranial magnetic stimulation studies of normal and disordered speech. Yet, somatotopy has been challenged by studies showing overlap among the effectors within the homunculus. In order to address this dichotomy, we performed four voxel-based meta-analyses of 54 functional neuroimaging studies of non-speech tasks involving respiration, lip movement, tongue movement, and swallowing, respectively. While the centers of mass of the clusters supported the classic homuncular view of the motor cortex, there was significant variability in the locations of the activation-coordinates among studies, resulting in an overlapping arrangement. This "somatotopy with overlap" might reflect the intrinsic functional interconnectedness of the oral effectors for speech production. PMID:20171727

Takai, Osamu; Brown, Steven; Liotti, Mario

2010-04-01

342

Molecular Pathways: Targeting the Kinase Effectors of RHO-Family GTPases.  

PubMed

RHO GTPases, members of the RAS superfamily of small GTPases, are adhesion and growth factor-activated molecular switches that play important roles in tumor development and progression. When activated, RHO-family GTPases such as RAC1, CDC42, and RHOA, transmit signals by recruiting a variety of effector proteins, including the protein kinases PAK, ACK, MLK, MRCK, and ROCK. Genetically induced loss of RHO function impedes transformation by a number of oncogenic stimuli, leading to an interest in developing small-molecule inhibitors that either target RHO GTPases directly, or that target their downstream protein kinase effectors. Although inhibitors of RHO GTPases and their downstream signaling kinases have not yet been widely adopted for clinical use, their potential value as cancer therapeutics continues to facilitate pharmaceutical research and development and is a promising therapeutic strategy. Clin Cancer Res; 21(1); 24-29. ©2014 AACR. PMID:25336694

Prudnikova, Tatiana Y; Rawat, Sonali J; Chernoff, Jonathan

2015-01-01

343

System design description for the LDUA common video end effector system (CVEE)  

SciTech Connect

The Common Video End Effector System (CVEE), system 62-60, was designed by the Idaho National Engineering Laboratory (INEL) to provide the control interface of the various video end effectors used on the LDUA. The CVEE system consists of a Support Chassis which contains the input and output Opto-22 modules, relays, and power supplies and the Power Chassis which contains the bipolar supply and other power supplies. The combination of the Support Chassis and the Power Chassis make up the CVEE system. The CVEE system is rack mounted in the At Tank Instrument Enclosure (ATIE). Once connected it is controlled using the LDUA supervisory data acquisition system (SDAS). Video and control status will be displayed on monitors within the LDUA control center.

Pardini, A.F.

1998-01-27

344

BtpB, a novel Brucella TIR-containing effector protein with immune modulatory functions.  

PubMed

Several bacterial pathogens have TIR domain-containing proteins that contribute to their pathogenesis. We identified a second TIR-containing protein in Brucella spp. that we have designated BtpB. We show it is a potent inhibitor of TLR signaling, probably via MyD88. BtpB is a novel Brucella effector that is translocated into host cells and interferes with activation of dendritic cells. In vivo mouse studies revealed that BtpB is contributing to virulence and control of local inflammatory responses with relevance in the establishment of chronic brucellosis. Together, our results show that BtpB is a novel Brucella effector that plays a major role in the modulation of host innate immune response during infection. PMID:23847770

Salcedo, Suzana P; Marchesini, María I; Degos, Clara; Terwagne, Matthieu; Von Bargen, Kristine; Lepidi, Hubert; Herrmann, Claudia K; Santos Lacerda, Thais L; Imbert, Paul R C; Pierre, Philippe; Alexopoulou, Lena; Letesson, Jean-Jacques; Comerci, Diego J; Gorvel, Jean-Pierre

2013-01-01

345

Simultaneous infiltration of polyfunctional effector and suppressor T cells into renal cell carcinomas.  

PubMed

Renal cell carcinoma is frequently infiltrated by cells of the immune system. This makes it important to understand interactions between cancer cells and immune cells so they can be manipulated to bring clinical benefit. Here, we analyze subsets and functions of T lymphocytes infiltrating renal cell tumors directly ex vivo following mechanical disaggregation and without any culture step. Subpopulations of memory and effector CD4(+) Th1, Th2, and Th17 and CD8(+) Tc1 cells were identified based on surface phenotype, activation potential, and multicytokine production. Compared with the same patient's peripheral blood, T lymphocytes present inside tumors were found to be enriched in functional CD4(+) cells of the Th1 lineage and in effector memory CD8(+) cells. Additionally, several populations of CD4(+) and CD8(+) regulatory T cells were identified that may synergize to locally dampen antitumor T-cell responses. PMID:19843860

Attig, Sebastian; Hennenlotter, Jörg; Pawelec, Graham; Klein, Gerd; Koch, Sven D; Pircher, Hanspeter; Feyerabend, Susan; Wernet, Dorothee; Stenzl, Arnulf; Rammensee, Hans-Georg; Gouttefangeas, Cécile

2009-11-01

346

The Crystal Structure of TAL Effector PthXo1 Bound to Its DNA Target  

SciTech Connect

DNA recognition by TAL effectors is mediated by tandem repeats, each 33 to 35 residues in length, that specify nucleotides via unique repeat-variable diresidues (RVDs). The crystal structure of PthXo1 bound to its DNA target was determined by high-throughput computational structure prediction and validated by heavy-atom derivatization. Each repeat forms a left-handed, two-helix bundle that presents an RVD-containing loop to the DNA. The repeats self-associate to form a right-handed superhelix wrapped around the DNA major groove. The first RVD residue forms a stabilizing contact with the protein backbone, while the second makes a base-specific contact to the DNA sense strand. Two degenerate amino-terminal repeats also interact with the DNA. Containing several RVDs and noncanonical associations, the structure illustrates the basis of TAL effector-DNA recognition.

Mak, Amanda Nga-Sze; Bradley, Philip; Cernadas, Raul A.; Bogdanove, Adam J.; Stoddard, Barry L. (FHCRC); (Iowa State)

2012-02-10

347

BtpB, a novel Brucella TIR-containing effector protein with immune modulatory functions  

PubMed Central

Several bacterial pathogens have TIR domain-containing proteins that contribute to their pathogenesis. We identified a second TIR-containing protein in Brucella spp. that we have designated BtpB. We show it is a potent inhibitor of TLR signaling, probably via MyD88. BtpB is a novel Brucella effector that is translocated into host cells and interferes with activation of dendritic cells. In vivo mouse studies revealed that BtpB is contributing to virulence and control of local inflammatory responses with relevance in the establishment of chronic brucellosis. Together, our results show that BtpB is a novel Brucella effector that plays a major role in the modulation of host innate immune response during infection. PMID:23847770

Salcedo, Suzana P.; Marchesini, María I.; Degos, Clara; Terwagne, Matthieu; Von Bargen, Kristine; Lepidi, Hubert; Herrmann, Claudia K.; Santos Lacerda, Thais L.; Imbert, Paul R. C.; Pierre, Philippe; Alexopoulou, Lena; Letesson, Jean-Jacques; Comerci, Diego J.; Gorvel, Jean-Pierre

2013-01-01

348

DNase ? Is the Effector Endonuclease for Internucleosomal DNA Fragmentation in Necrosis  

PubMed Central

Apoptosis and necrosis, two major forms of cell death, can be distinguished morphologically and biochemically. Internucleosomal DNA fragmentation (INDF) is a biochemical hallmark of apoptosis, and caspase-activated DNase (CAD), also known as DNA fragmentation factor 40 kDa (DFF40), is one of the major effector endonucleases. DNase ?, a Mg2+/Ca2+-dependent endonuclease, is also known to generate INDF but its role among other apoptosis-associated endonucleases in cell death is unclear. Here we show that (i) INDF occurs even during necrosis in cell lines, primary cells, and in tissues of mice in vivo, and (ii) DNase ?, but not CAD, is the effector endonuclease for INDF in cells undergoing necrosis. These results document a previously unappreciated role for INDF in necrosis and define its molecular basis. PMID:24312463

Mizuta, Ryushin; Araki, Shinsuke; Furukawa, Makoto; Furukawa, Yuki; Ebara, Syota; Shiokawa, Daisuke; Hayashi, Katsuhiko; Tanuma, Sei-ichi; Kitamura, Daisuke

2013-01-01

349

Test plan for the remote conveyance and innovative end effector demonstration  

SciTech Connect

This test plan describes the demonstration of innovative equipment and processes specifically designed to be superior to currently employed technology for buried waste retrieval. The dumping of dry soil into a funnel/dumpster arrangement has been found to be the primary mechanism for dust generation during the retrieval of buried transuranic waste. The primary goal of the innovative end effector is to reduce dust generation and the potential spread of airborne contaminants during the dumping operation. In addition, regardless of the excavation technique, exhumed waste will have to be conveyed away from the retrieval area to a packaging area or directly to a treatment facility. The remote conveyance system is aimed at developing a remotely controlled vehicle to convey retrieved waste that will operate on variable terrain and remove workers from the hazardous zone. To demonstrate the remote conveyance system and the innovative end effector, the Buried Waste Integrated Demonstration (BWID) Program has subcontracted with RAHCO International to provide equipment and services to perform a demonstration of the technologies. The demonstration will be performed in two phases. In Phase I, the subcontractor will perform a full scale demonstration to assess the ability of the innovative end effector to control dust generation and the potential spread of contamination during dumping operations. Phase II includes performing a retrieval/conveyance demonstration. This demonstration will excavate, dump, and convey simulated waste to demonstrate the functionality of the system (e.g., maneuverability, retrieval rates, and system integration). Phase II of the demonstration will include all elements of the remote conveyance and end effector system. This test plan will describe the demonstration objectives, data quality objectives, equipment operation, and methods for collecting data during the demonstration.

Rice, P.; Smith, A.M. [EG& G Idaho, Inc., Idaho Falls, ID (United States). Idaho National Engineering Lab.; Peterson, R.

1994-08-01

350

A General Strategy for Effector-mediated Control of RNA-cleaving Ribozymes and DNA Enzymes  

Microsoft Academic Search

A novel and general approach is described for generating versions of RNA-cleaving ribozymes (RNA enzymes) and DNAzymes (DNA enzymes), whose catalytic activity can be controlled by the binding of activator molecules. Variants of the RNA-cleaving 10–23 DNAzyme and 8–17 DNAzyme were created, whose catalysis was activated by up to ?35-fold by the binding of the effector adenosine. The design of

Dennis Y. Wang; Beatrice H. Y. Lai; Dipankar Sen

2002-01-01

351

Impact of Fc Glycosylation on Monoclonal Antibody Effector Functions and Degradation by Proteases  

Microsoft Academic Search

\\u000a IgGs are required to be N-glycosylated in the CH2 domain of the Fc to exhibit effector functions including antibody dependent cellular cytotoxicity (ADCC) and complement dependent\\u000a cytotoxicity (CDC). This is because Fc glycosylation impacts antibody binding to Fc receptors and complement activating protein,\\u000a C1q. Glycans found in the Fc are mainly complex biantennary structures with a high degree of heterogeneity

T. Shantha Raju

352

Characterization of cell death inducing Phytophthora capsici CRN effectors suggests diverse activities in the host nucleus.  

PubMed

Plant-Microbe interactions are complex associations that feature recognition of Pathogen Associated Molecular Patterns by the plant immune system and dampening of subsequent responses by pathogen encoded secreted effectors. With large effector repertoires now identified in a range of sequenced microbial genomes, much attention centers on understanding their roles in immunity or disease. These studies not only allow identification of pathogen virulence factors and strategies, they also provide an important molecular toolset suited for studying immunity in plants. The Phytophthora intracellular effector repertoire encodes a large class of proteins that translocate into host cells and exclusively target the host nucleus. Recent functional studies have implicated the CRN protein family as an important class of diverse effectors that target distinct subnuclear compartments and modify host cell signaling. Here, we characterized three necrosis inducing CRNs and show that there are differences in the levels of cell death. We show that only expression of CRN20_624 has an additive effect on PAMP induced cell death but not AVR3a induced ETI. Given their distinctive phenotypes, we assessed localization of each CRN with a set of nuclear markers and found clear differences in CRN subnuclear distribution patterns. These assays also revealed that expression of CRN83_152 leads to a distinct change in nuclear chromatin organization, suggesting a distinct series of events that leads to cell death upon over-expression. Taken together, our results suggest diverse functions carried by CRN C-termini, which can be exploited to identify novel processes that take place in the host nucleus and are required for immunity or susceptibility. PMID:24155749

Stam, Remco; Howden, Andrew J M; Delgado-Cerezo, Magdalena; M M Amaro, Tiago M; Motion, Graham B; Pham, Jasmine; Huitema, Edgar

2013-01-01

353

Characterization of cell death inducing Phytophthora capsici CRN effectors suggests diverse activities in the host nucleus  

PubMed Central

Plant-Microbe interactions are complex associations that feature recognition of Pathogen Associated Molecular Patterns by the plant immune system and dampening of subsequent responses by pathogen encoded secreted effectors. With large effector repertoires now identified in a range of sequenced microbial genomes, much attention centers on understanding their roles in immunity or disease. These studies not only allow identification of pathogen virulence factors and strategies, they also provide an important molecular toolset suited for studying immunity in plants. The Phytophthora intracellular effector repertoire encodes a large class of proteins that translocate into host cells and exclusively target the host nucleus. Recent functional studies have implicated the CRN protein family as an important class of diverse effectors that target distinct subnuclear compartments and modify host cell signaling. Here, we characterized three necrosis inducing CRNs and show that there are differences in the levels of cell death. We show that only expression of CRN20_624 has an additive effect on PAMP induced cell death but not AVR3a induced ETI. Given their distinctive phenotypes, we assessed localization of each CRN with a set of nuclear markers and found clear differences in CRN subnuclear distribution patterns. These assays also revealed that expression of CRN83_152 leads to a distinct change in nuclear chromatin organization, suggesting a distinct series of events that leads to cell death upon over-expression. Taken together, our results suggest diverse functions carried by CRN C-termini, which can be exploited to identify novel processes that take place in the host nucleus and are required for immunity or susceptibility. PMID:24155749

Stam, Remco; Howden, Andrew J. M.; Delgado-Cerezo, Magdalena; M. M. Amaro, Tiago M.; Motion, Graham B.; Pham, Jasmine; Huitema, Edgar

2013-01-01

354

Effector cells in natural cytotoxicity against human bladder cancer cell lines  

Microsoft Academic Search

Human peripheral blood mononuclear cells obtained by ficoll-hypaque sedimentation were depleted of Fc-receptor-bearing (FcR+) cells. Cytotoxicity (direct killing of target cells by effector cells), tested in a 40 h assay, was significantly decreased against a variety of target cells. Tests in which no FcR+ cells could be detected were also positive for “natural killing” (NK) against a spectrum of target

Eda T. Bloom; Marguerite Dunsworth-Browne; Diane Durkos-Smith

1981-01-01

355

The Crystal Structure of TAL Effector PthXo1 Bound to Its DNA Target  

Microsoft Academic Search

DNA recognition by TAL effectors is mediated by tandem repeats, each 33 to 35 residues in length, that specify nucleotides via unique repeat-variable diresidues (RVDs). The crystal structure of PthXo1 bound to its DNA target was determined by high-throughput computational structure prediction and validated by heavy-atom derivatization. Each repeat forms a left-handed, two-helix bundle that presents an RVD-containing loop to

Amanda Nga-Sze Mak; Philip Bradley; Raul A. Cernadas; Adam J. Bogdanove; Barry L. Stoddard

2012-01-01

356

Thermodynamic Mapping of Effector Protein Interfaces with RalA and RalB.  

PubMed

RalA and RalB are members of the Ras family of small G proteins and are activated downstream of Ras via RalGEFs. The RalGEF-Ral axis represents one of the major effector pathways controlled by Ras and as such is an important pharmacological target. RalA and RalB are approximately 80% identical at the amino acid level; despite this, they have distinct roles both in normal cells and in the disease state. We have used our structure of RalB-RLIP76 to guide an analysis of Ral-effector interaction interfaces, creating panels of mutant proteins to probe the energetics of these interactions. The data provide a physical mechanism that underpins the effector selective mutations commonly employed to dissect Ral G protein function. Comparing the energetic landscape of the RalB-RLIP76 and RalB-Sec5 complexes reveals mutations in RalB that lead to differential binding of the two effector proteins. A panel of RLIP76 mutants was used to probe the interaction between RLIP76 and RalA and -B. Despite 100% sequence identity in the RalA and -B contact residues with RLIP76, differences still exist in the energetic profiles of the two complexes. Therefore, we have revealed properties that may account for some of the functional separation observed with RalA and RalB at the cellular level. Our mutations, in both the Ral isoforms and RLIP76, provide new tools that can be employed to parse the complex biology of Ral G protein signaling networks. The combination of these thermodynamic and structural data can also guide efforts to ablate RalA and -B activity with small molecules and peptides. PMID:25621740

Campbell, Louise J; Peppa, Maria; Crabtree, Michael D; Shafiq, Arooj; McGough, Nicholas F; Mott, Helen R; Owen, Darerca

2015-02-17

357

Human Effector and Memory CD8 + T Cell Responses to Smallpox and Yellow Fever Vaccines  

Microsoft Academic Search

SUMMARY ToexplorethehumanTcellresponsetoacuteviralin- fection, we performed a longitudinal analysis of CD8+ T cells responding to the live yellow fever virus and smallpox vaccines—two highly successful human vaccines. Our results show that both vaccines gener- ated a brisk primary effector CD8+ T cell response of substantial magnitude that could be readily quanti- tated with a simple set of four phenotypic markers. Secondly,

Joseph D. Miller; Robbert G. van der Most; Rama S. Akondy; John T. Glidewell; Sophia Albott; David Masopust; Kaja Murali-Krishna; Patryce L. Mahar; Srilatha Edupuganti; Susan Lalor; Stephanie Germon; Carlos Del Rio; Silvija I. Staprans; John D. Altman; Mark B. Feinberg; Rafi Ahmed

2008-01-01

358

Linear Scarifying End-Effector Developed For Wall Cleaning In Underground Storage Tanks  

SciTech Connect

This paper describes the development and performance of a Linear Scarifying End-Effector (LSEE) designed and fabricated for deployment by a remotely operated vehicle. The end-effector was designed to blast or scarify in-grained residual contamination from gunite tank walls using high-pressure water jets after the bulk sludge had been removed from the tanks using an integrated suite of remotely operated tools. Two generations of the LSEE were fabricated, tested, and deployed in the gunite tanks at the Oak Ridge National Laboratory, with varying levels of success. Because the LSEE was designed near the end of a four-year project to clean up the gunite tanks at Oak Ridge, a number of design constraints existed. The end-effector had to utilize pneumatic, hydraulic and electrical interfaces already available at the site; and to be deployable through one of the containment structures already in place for the other remote systems. Another primary design consideration was that the tool had to effectively extend the reach of an existing remotely operated vehicle from six ft. to at least ten ft. to allow cleaning the tank walls from floor to ceiling. In addition, the combined weight and thrust of the LSEE had to be manageable by the manipulator mounted on the vehicle. Finally, the end-effector had to follow an autonomous scarifying path such that the vehicle was only required to reposition the unit at the end of each pass after the mist had cleared from the tank. The prototypes successfully met each of these challenges, but did encounter other difficulties during actual tank operations.

Fitzgerald, C.L.F.

2001-02-04

359

Global Impact of Salmonella Pathogenicity Island 2-secreted Effectors on the Host Phosphoproteome*  

PubMed Central

During the late stages of infection, Salmonella secretes numerous effectors through a type III secretion system that is encoded within Salmonella pathogenicity island 2 (SPI2). Despite the importance of SPI2 as a major virulence factor leading to the systemic spread of the bacteria and diseases, a global view of its effects on host responses is still lacking. Here, we measured global impacts of SPI2 effectors on the host phosphorylation and protein expression levels in RAW264.7 and in HeLa cells, as macrophage and nonphagocytic models of infection. We observe that SPI2 effectors differentially modulate the host phosphoproteome and cellular processes (e.g. protein trafficking, cytoskeletal regulation, and immune signaling) in a host cell-dependent manner. Our unbiased approach reveals the involvement of many previously unrecognized proteins, including E3 ligases (HERC4, RanBP2, and RAD18), kinases (CDK, SIK3, and WNK1), and histones (H2B1F, H4, and H15), in late stages of Salmonella infection. Furthermore, from this phosphoproteome analysis and other quantitative screens, we identified HSP27 as a direct in vitro and in vivo molecular target of the only type III secreted kinase, SteC. Using biochemical and cell biological assays, we demonstrate that SteC phosphorylates multiple sites in HSP27 and induces actin rearrangement through this protein. Together, these results provide a broader landscape of host players contributing to specific processes/pathways mediated by SPI2 effectors than was previously appreciated. PMID:23459991

Imami, Koshi; Bhavsar, Amit P.; Yu, Hongbing; Brown, Nat F.; Rogers, Lindsay D.; Finlay, B. Brett; Foster, Leonard J.

2013-01-01

360

Rapid parallel flow cytometry assays of active GTPases using effector beads  

PubMed Central

We describe a rapid assay for measuring the cellular activity of small GTPases in response to a specific stimulus. Effector functionalized beads are used to quantify in parallel multiple, GTP-bound GTPases in the same cell lysate by flow cytometry. In a biologically relevant example, five different Ras family GTPases are shown for the first time to be involved in a concerted signaling cascade downstream of receptor ligation by Sin Nombre hantavirus. PMID:23928044

Buranda, Tione; BasuRay, Soumik; Swanson, Scarlett; Agola, Jacob; Bondu, Virginie; Wandinger-Ness, Angela

2013-01-01

361

During STS-57, EURECA is grappled by OV-105's RMS end effector  

NASA Technical Reports Server (NTRS)

During STS-57, the European Retrievable Carrier (EURECA) is grappled by Endeavour's, Orbiter Vehicle (OV) 105's, remote manipulator system (RMS) end effector and is held in transfer to retrieval orbit before being stowed in the payload bay (PLB) for return to Earth. The southern two-thirds of the state of Florida, part of the Gulf of Mexico, and clouds over the Atlantic Ocean form the backdrop.

1993-01-01

362

EST mining and functional expression assays identify extracellular effector proteins from the plant pathogen Phytophthora.  

PubMed

Plant pathogenic microbes have the remarkable ability to manipulate biochemical, physiological, and morphological processes in their host plants. These manipulations are achieved through a diverse array of effector molecules that can either promote infection or trigger defense responses. We describe a general functional genomics approach aimed at identifying extracellular effector proteins from plant pathogenic microorganisms by combining data mining of expressed sequence tags (ESTs) with virus-based high-throughput functional expression assays in plants. PexFinder, an algorithm for automated identification of extracellular proteins from EST data sets, was developed and applied to 2147 ESTs from the oomycete plant pathogen Phytophthora infestans. The program identified 261 ESTs (12.2%) corresponding to a set of 142 nonredundant Pex (Phytophthora extracellular protein) cDNAs. Of these, 78 (55%) Pex cDNAs were novel with no significant matches in public databases. Validation of PexFinder was performed using proteomic analysis of secreted protein of P. infestans. To identify which of the Pex cDNAs encode effector proteins that manipulate plant processes, high-throughput functional expression assays in plants were performed on 63 of the identified cDNAs using an Agrobacterium tumefaciens binary vector carrying the potato virus X (PVX) genome. This led to the discovery of two novel necrosis-inducing cDNAs, crn1 and crn2, encoding extracellular proteins that belong to a large and complex protein family in Phytophthora. Further characterization of the crn genes indicated that they are both expressed in P. infestans during colonization of the host plant tomato and that crn2 induced defense-response genes in tomato. Our results indicate that combining data mining using PexFinder with PVX-based functional assays can facilitate the discovery of novel pathogen effector proteins. In principle, this strategy can be applied to a variety of eukaryotic plant pathogens, including oomycetes, fungi, and nematodes. PMID:12840044

Torto, Trudy A; Li, Shuang; Styer, Allison; Huitema, Edgar; Testa, Antonino; Gow, Neil A R; van West, Pieter; Kamoun, Sophien

2003-07-01

363

Neutrophils Are Essential As A Source Of Il-17 In The Effector Phase Of Arthritis  

PubMed Central

Objective Th17 has been shown to have a pivotal role in the development of arthritis. However, the role of IL-17 in the T cell-independent effector phase has not fully been examined. We investigated whether IL-17 is involved in the effector phase of arthritis by using K/BxN serum-induced arthritis model. Methods K/BxN serum was transferred into IL-17 knockout (KO) mice, SCID mice and their control mice, and arthritis was evaluated over time. In order to clarify the source of IL-17 in the effector phase, neutrophils or CD4+ T cells collected from IL-17 KO or control mice were injected into IL-17 KO recipient mice together with K/BxN serum. To examine if neutrophils secrete IL-17 upon stimulation, neutrophils were stimulated with immune complex in?vitro and IL-17 in the supernatant was measured by ELISA. Results K/BxN serum-induced arthritis was much less severe in IL-17 KO mice than in WT mice. Since K/BxN serum-transferred SCID mice developed severe arthritis with high serum IL-17 concentration, we speculated neutrophils are the responsible player as an IL-17 source. When wild type (WT) but not IL-17 KO neutrophils were co-injected with K/BxN serum into IL-17 KO mice, arthritis was exacerbated, whereas co-injection of WT CD4+ T cells had no effect. In vitro, stimulation of neutrophils with immune complexcaused IL-17 secretion. Conclusions Neutrophils are essential as a source of IL-17 in the effector phase of arthritis. The trigger of secreting IL-17 from neutrophils may be immune complex. PMID:23671588

Katayama, Masaki; Ohmura, Koichiro; Yukawa, Naoichiro; Terao, Chikashi; Hashimoto, Motomu; Yoshifuji, Hajime; Kawabata, Daisuke; Fujii, Takao; Iwakura, Yoichiro; Mimori, Tsuneyo

2013-01-01

364

System properties, feedback control and effector coordination of human temperature regulation.  

PubMed

The aim of human temperature regulation is to protect body processes by establishing a relative constancy of deep body temperature (regulated variable), in spite of external and internal influences on it. This is basically achieved by a distributed multi-sensor, multi-processor, multi-effector proportional feedback control system. The paper explains why proportional control implies inherent deviations of the regulated variable from the value in the thermoneutral zone. The concept of feedback of the thermal state of the body, conveniently represented by a high-weighted core temperature (T (c)) and low-weighted peripheral temperatures (T (s)) is equivalent to the control concept of "auxiliary feedback control", using a main (regulated) variable (T (c)), supported by an auxiliary variable (T (s)). This concept implies neither regulation of T (s) nor feedforward control. Steady-states result in the closed control-loop, when the open-loop properties of the (heat transfer) process are compatible with those of the thermoregulatory processors. They are called operating points or balance points and are achieved due to the inherent property of dynamical stability of the thermoregulatory feedback loop. No set-point and no comparison of signals (e.g. actual-set value) are necessary. Metabolic heat production and sweat production, though receiving the same information about the thermal state of the body, are independent effectors with different thresholds and gains. Coordination between one of these effectors and the vasomotor effector is achieved by the fact that changes in the (heat transfer) process evoked by vasomotor control are taken into account by the metabolic/sweat processor. PMID:19787369

Werner, Jürgen

2010-05-01

365

Genome engineering with TAL-effector nucleases and alternative modular nuclease technologies.  

PubMed

Over three years following the discovery of the TAL code, artificial TAL effector DNA binding domains have emerged as the premier platform for building site-specific DNA binding polypeptides for use in biological research. Here, we provide an overview of TAL effector and alternative modular DNA binding domain (mDBD) technologies, focusing on their use in established and emerging architectures for building site-specific endonucleases for genome engineering applications. We also discuss considerations for choosing TAL effector/mDBD or alternative nuclease technologies for genome engineering projects ranging from basic laboratory gene editing of cultured cell lines to therapeutics. Finally, we highlight how the rapid pace of development of mDBD-based, such as monomeric TALENs (I-TevI-TAL), and more recently RNA-guided nucleases (CRISPR-Cas9) has led to a transition in the field of genome engineering towards development of the next generation of technologies aimed at controlling events that occur after targeted DNA breaks are made. PMID:23888878

Scharenberg, Andrew M; Duchateau, Philippe; Smith, Julianne

2013-08-01

366

Association Rate Constants of Ras-Effector Interactions Are Evolutionarily Conserved  

PubMed Central

Evolutionary conservation of protein interaction properties has been shown to be a valuable indication for functional importance. Here we use homology interface modeling of 10 Ras-effector complexes by selecting ortholog proteins from 12 organisms representing the major eukaryotic branches, except plants. We find that with increasing divergence time the sequence similarity decreases with respect to the human protein, but the affinities and association rate constants are conserved as predicted by the protein design algorithm, FoldX. In parallel we have done computer simulations on a minimal network based on Ras-effector interactions, and our results indicate that in the absence of negative feedback, changes in kinetics that result in similar binding constants have strong consequences on network behavior. This, together with the previous results, suggests an important biological role, not only for equilibrium binding constants but also for kinetics in signaling processes involving Ras-effector interactions. Our findings are important to take into consideration in system biology approaches and simulations of biological networks. PMID:19096503

Kiel, Christina; Aydin, Dorothee; Serrano, Luis

2008-01-01

367

Multinucleation during C. trachomatis Infections Is Caused by the Contribution of Two Effector Pathways  

PubMed Central

Chlamydia trachomatis is an obligate intracellular bacterial pathogen and the second leading cause of sexually transmitted infections in the US. Infections cause significant morbidity and can lead to serious reproductive sequelae, including an epidemiological link to increased rates of reproductive cancers. One of the overt changes that infected cells exhibit is the development of genomic instability leading to multinucleation. Here we demonstrate that the induction of multinucleation is not conserved equally across chlamydial species; C. trachomatis L2 caused high levels of multinucleation, C. muridarum intermediate levels, and C. caviae had very modest effects on multinucleation. Our data show that at least two effector pathways together cause genomic instability during infection leading to multinucleation. We find that the highly conserved chlamydial protease CPAF is a key effector for one of these pathways. CPAF secretion is required for the loss of centrosome duplication regulation as well as inducing early mitotic exit. The second effector pathway involves the induction of centrosome position errors. This function is not conserved in three chlamydial species tested. Together these two pathways contribute to the induction of high levels of genomic instability and multinucleation seen in C. trachomatis infections. PMID:24955832

Brown, Heather M.; Knowlton, Andrea E.; Snavely, Emily; Nguyen, Bidong D.; Richards, Theresa S.; Grieshaber, Scott S.

2014-01-01

368

Effector granules in human T lymphocytes: the luminal proteome of secretory lysosomes from human T cells  

PubMed Central

Background Cytotoxic cells of the immune system have evolved a lysosomal compartment to store and mobilize effector molecules. In T lymphocytes and NK cells, the death factor FasL is one of the characteristic marker proteins of these so-called secretory lysosomes, which combine properties of conventional lysosomes and exocytotic vesicles. Although these vesicles are crucial for immune effector function, their protein content in T cells has so far not been investigated in detail. Results In the present study, intact membranous vesicles were enriched from homogenates of polyclonally activated T cells and initially characterized by Western blotting and electron microscopic inspection. The vesicular fraction that contained the marker proteins of secretory lysosomes was subsequently analyzed by 2D electrophoresis and mass spectrometry. The proteome analysis and data evaluation revealed that 70% of the 397 annotated proteins had been associated with different lysosome-related organelles in previous proteome studies. Conclusion We provide the first comprehensive proteome map of T cell-derived secretory lysosomes with only minor contaminations by cytosolic, nuclear or other proteins. This information will be useful to more precisely address the activation-dependent maturation and the specific distribution of effector organelles and proteins in individual T or NK cell populations in future studies. PMID:21255389

2011-01-01

369

SNARE molecular mimicry by a Legionella pneumophila Dot/Icm effector.  

PubMed

Upon infection, Legionella pneumophila uses the Dot/Icm type IV secretion system to translocate effector proteins from the Legionella-containing vacuole (LCV) into the host cell cytoplasm. The effectors target a wide array of host cellular processes that aid LCV biogenesis, including the manipulation of membrane trafficking. In this study, we used a hidden Markov model screen to identify two novel, non-eukaryotic SNARE homologs: the bacterial LseA and viral VshA proteins. We characterized LseA as a Dot/Icm effector of L.?pneumophila, which has close homology to the Qc-SNARE subfamily. The lseA gene was present in multiple sequenced L.?pneumophila strains including Corby and was well distributed amongst L.?pneumophila clinical and environmental isolates. Employing a variety of biochemical, cell biological and microbiological techniques, we found that farnesylated LseA localized to membranes associated with the Golgi complex in mammalian cells and LseA interacted with a subset of Qa-, Qb- and R-SNAREs in host cells. Our results suggested that LseA acts as a SNARE protein and has the potential to regulate or mediate membrane fusion events in Golgi-associated pathways. PMID:25488819

King, Nathan P; Newton, Patrice; Schuelein, Ralf; Brown, Darren L; Petru, Marketa; Zarsky, Vojtech; Dolezal, Pavel; Luo, Lin; Bugarcic, Andrea; Stanley, Amanda C; Murray, Rachael Z; Collins, Brett M; Teasdale, Rohan D; Hartland, Elizabeth L; Stow, Jennifer L

2014-12-01

370

Crystal structure of the effector protein XOO4466 from Xanthomonas oryzae.  

PubMed

Many Gram-negative bacteria deliver their virulence factors into host cells through a secretion system. Those factors, called effector proteins, are involved in the pathogenicity in host cells by interfering with various cellular events. The phytopathogen Xanthomonas oryzae pv. oryzae uses a type III secretion system to inject its effectors, but the functional roles of these proteins remain largely uncharacterized. Here, we determined a crystal structure of XOO4466, an effector from X. oryzae pv. oryzae, and performed a functional analysis. We determined that XOO4466 is similar in sequence to Xanthomonas outer protein Q, a putative nucleoside hydrolase (NH). The overall structure of XOO4466 is homologous to that of NHs, including a metal-binding site, but differs in its oligomeric state and active site topology. Further analysis indicated that antiparallel ?-strands commonly found in NHs adjacent to the active site loop are replaced in XOO4466 with a short loop, causing the active site loop to adopt a conformation distinct from that of NHs. Thus, the catalytic residues emanating from the respective active site loop of NHs are absent in the putative active site of XOO4466. Consistent with these structural features, a functional assay indicated that XOO4466 does not exhibit NH activity and possibly catalyzes yet unknown reactions. PMID:24007778

Yu, Sangheon; Hwang, Ingyu; Rhee, Sangkee

2013-11-01

371

Activation of effector immune cells promotes tumor stochastic extinction: A homotopy analysis approach  

E-print Network

In this article we provide homotopy solutions of a cancer nonlinear model describing the dynamics of tumor cells in interaction with healthy and effector immune cells. We apply a semi-analytic technique for solving strongly nonlinear systems - the Step Homotopy Analysis Method (SHAM). This algorithm, based on a modification of the standard homotopy analysis method (HAM), allows to obtain a one-parameter family of explicit series solutions. By using the homotopy solutions, we first investigate the dynamical effect of the activation of the effector immune cells in the deterministic dynamics, showing that an increased activation makes the system to enter into chaotic dynamics via a period-doubling bifurcation scenario. Then, by adding demographic stochasticity into the homotopy solutions, we show, as a difference from the deterministic dynamics, that an increased activation of the immune cells facilitates cancer clearance involving tumor cells extinction and healthy cells persistence. Our results highlight the importance of therapies activating the effector immune cells at early stages of cancer progression.

Josep Sardanyés; Carla Rodrigues; Cristina Januário; Nuno Martins; Gabriel Gil-Gómez; Jorge Duarte

2014-11-28

372

Interferon regulatory factor 4 sustains CD8+ T cell expansion and effector differentiation  

PubMed Central

SUMMARY Upon infection, CD8+ T cells undergo a stepwise process of early activation, expansion and differentiation into effector cells. How these phases are transcriptionally regulated is incompletely defined. Here, we report that interferon regulatory factor 4 (IRF4), dispensable for early CD8+ T cell activation, was vital for sustaining the expansion and effector differentiation of CD8+ T cells. Mechanistically, IRF4 promoted the expression and function of Blimp1 and T-bet, two transcription factors required for CD8+ T cell effector differentiation, while repressed genes that mediate cell cycle arrest and apoptosis. Selective ablation of Irf4 in peripheral CD8+ T cells impaired anti-viral CD8+ T cell responses, viral clearance and CD8+ T cell-mediated host recovery from influenza infection. IRF4 expression was regulated by T cell receptor (TCR) signaling strength via mammalian target of rapamycin (mTOR). Our data reveal that IRF4 translates differential strength of TCR-signaling into different quantitative and qualitative CD8+ T cell responses. PMID:24211184

Yao, Shuyu; Buzo, Bruno Fernando d.; Pham, Duy; Jiang, Li; Taparowsky, Elizabeth J.; Kaplan, Mark H.; Sun, Jie

2013-01-01

373

Duplications and losses in gene families of rust pathogens highlight putative effectors  

PubMed Central

Rust fungi are a group of fungal pathogens that cause some of the world's most destructive diseases of trees and crops. A shared characteristic among rust fungi is obligate biotrophy, the inability to complete a lifecycle without a host. This dependence on a host species likely affects patterns of gene expansion, contraction, and innovation within rust pathogen genomes. The establishment of disease by biotrophic pathogens is reliant upon effector proteins that are encoded in the fungal genome and secreted from the pathogen into the host's cell apoplast or within the cells. This study uses a comparative genomic approach to elucidate putative effectors and determine their evolutionary histories. We used OrthoMCL to identify nearly 20,000 gene families in proteomes of 16 diverse fungal species, which include 15 basidiomycetes and one ascomycete. We inferred patterns of duplication and loss for each gene family and identified families with distinctive patterns of expansion/contraction associated with the evolution of rust fungal genomes. To recognize potential contributors for the unique features of rust pathogens, we identified families harboring secreted proteins that: (i) arose or expanded in rust pathogens relative to other fungi, or (ii) contracted or were lost in rust fungal genomes. While the origin of rust fungi appears to be associated with considerable gene loss, there are many gene duplications associated with each sampled rust fungal genome. We also highlight two putative effector gene families that have expanded in Cqf that we hypothesize have roles in pathogenicity. PMID:25018762

Pendleton, Amanda L.; Smith, Katherine E.; Feau, Nicolas; Martin, Francis M.; Grigoriev, Igor V.; Hamelin, Richard; Nelson, C. Dana; Burleigh, J. Gordon; Davis, John M.

2014-01-01

374

CYK4 inhibits Rac1-dependent PAK1 and ARHGEF7 effector pathways during cytokinesis  

PubMed Central

In mitosis, animal cells lose their adhesion to the surrounding surfaces and become rounded. During mitotic exit, they reestablish these adhesions and at the same time physically contract and divide. How these competing processes are spatially segregated at the cell cortex remains mysterious. To address this question, we define the specific effector pathways used by RhoA and Rac1 in mitotic cells. We demonstrate that the MKlp1–CYK4 centralspindlin complex is a guanosine triphosphatase–activating protein (GAP) for Rac1 and not RhoA and that CYK4 negatively regulated Rac1 activity at the cell equator in anaphase. Cells expressing a CYK4 GAP mutant had defects in cytokinesis and showed elevated staining for the cell adhesion marker vinculin. These defects could be rescued by depletion of ARHGEF7 and p21-activated kinase, Rac1-specific effector proteins required for cell adhesion. Based on these findings, we propose that CYK4 GAP activity is required during anaphase to inhibit Rac1-dependent effector pathways associated with control of cell spreading and adhesion. PMID:22945935

Bastos, Ricardo Nunes; Penate, Xenia; Bates, Michelle; Hammond, Dean

2012-01-01

375

The costs of suppressing stressful memories  

Microsoft Academic Search

We investigated the costs of suppressing emotional and nonemotional memories, as evidenced in response times on a concurrent sentence verification task with three levels of syntactic complexity. Participants suppressing memories of personal negative experiences (n=26) had slower response times compared to the control group (n=23) and to participants suppressing nonemotional memories (n=25) particularly on the most complex sentences. Participants suppressing

Kitty Klein; Kevin Bratton

2007-01-01

376

Empirical investigations of thought suppression in OCD  

Microsoft Academic Search

Cognitive-behavioural models of obsessive-compulsive disorder (OCD) implicate thought suppression as a key factor in the development and persistence of the disorder. There is now more than a decade of research on thought suppression and its effects as they pertain to OCD. This paper briefly reports on initial thought suppression research and then offers a detailed review of recent thought suppression

Christine Purdon

2004-01-01

377

Host-Induced gene silencing in barley powdery mildew reveals a class of ribonuclease-like effectors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Obligate biotrophic pathogens of plants require the ability to circumvent host defenses to enable colonization. To establish compatibility, pathogens secrete a variety of effectors, which regulate host immunity, and thus, facilitate the establishment of haustorial feeding structures. These structur...

378

The actin-binding protein UNC-115 is an effector of Rac signaling during axon pathfinding in C-elegans  

E-print Network

Rac GTPases control cell shape by regulating downstream effectors that influence the actin cytoskeleton. UNC-115, a putative actin-binding protein similar to human abLIM/limatin, has previously been implicated in axon pathfinding. We have discovered...

Struckhoff, Eric Charles; Lundquist, Erik A.

2003-02-01

379

Joint-space adaptive control of a 6 DOF end-effector with closed-kinematic chain mechanism  

NASA Technical Reports Server (NTRS)

The development is presented for a joint-space adaptive scheme that controls the joint position of a six-degree-of-freedom (DOF) robot end-effector performing fine and precise motion within a very limited workspace. The end-effector was built to study autonomous assembly of NASA hardware in space. The design of the adaptive controller is based on the concept of model reference adaptive control (MRAC) and Lyapunov direct method. In the development, it is assumed that the end-effector performs slowly varying motion. Computer simulation is performed to investigate the performance of the developed control scheme on position control of the end-effector. Simulation results manifest that the adaptive control scheme provides excellent tracking of several test paths.

Nguyen, Charles C.; Zhou, Zhen-Lei

1989-01-01

380

CpG-A and B Oligodeoxynucleotides Enhance the Efficacy of Antibody Therapy by Activating Different Effector Cell Populations1  

Microsoft Academic Search

Immunostimulatory CpG oligodeoxynucleotides (ODNs) can enhance the therapeutic effect of monoclonal antibodies (mAbs) by enhancing antibody-dependent cell-mediated cytotoxicity (ADCC). Distinct classes of CpG ODNs have been found recently to stimulate different effector cell populations. We used murine cancer models to explore the role of various effector cell populations in the antitumor activity seen with mAbs com- bined with CpG ODNs

Heidi H. van Ojik; Lisette Bevaart; Christopher E. Dahle; Annie Bakker; Marco J. H. Jansen; Martine J. van Vugt; George J. Weiner

381

The machinery at endoplasmic reticulum-plasma membrane contact sites contributes to spatial regulation of multiple Legionella effector proteins.  

PubMed

The Dot/Icm system of the intracellular pathogen Legionella pneumophila has the capacity to deliver over 270 effector proteins into host cells during infection. Important questions remain as to spatial and temporal mechanisms used to regulate such a large array of virulence determinants after they have been delivered into host cells. Here we investigated several L. pneumophila effector proteins that contain a conserved phosphatidylinositol-4-phosphate (PI4P)-binding domain first described in the effector DrrA (SidM). This PI4P binding domain was essential for the localization of effectors to the early L. pneumophila-containing vacuole (LCV), and DrrA-mediated recruitment of Rab1 to the LCV required PI4P-binding activity. It was found that the host cell machinery that regulates sites of contact between the plasma membrane (PM) and the endoplasmic reticulum (ER) modulates PI4P dynamics on the LCV to control localization of these effectors. Specifically, phosphatidylinositol-4-kinase III? (PI4KIII?) was important for generating a PI4P signature that enabled L. pneumophila effectors to localize to the PM-derived vacuole, and the ER-associated phosphatase Sac1 was involved in metabolizing the PI4P on the vacuole to promote the dissociation of effectors. A defect in L. pneumophila replication in macrophages deficient in PI4KIII? was observed, highlighting that a PM-derived PI4P signature is critical for biogenesis of a vacuole that supports intracellular multiplication of L. pneumophila. These data indicate that PI4P metabolism by enzymes controlling PM-ER contact sites regulate the association of L. pneumophila effectors to coordinate early stages of vacuole biogenesis. PMID:24992562

Hubber, Andree; Arasaki, Kohei; Nakatsu, Fubito; Hardiman, Camille; Lambright, David; De Camilli, Pietro; Nagai, Hiroki; Roy, Craig R

2014-07-01

382

The Machinery at Endoplasmic Reticulum-Plasma Membrane Contact Sites Contributes to Spatial Regulation of Multiple Legionella Effector Proteins  

PubMed Central

The Dot/Icm system of the intracellular pathogen Legionella pneumophila has the capacity to deliver over 270 effector proteins into host cells during infection. Important questions remain as to spatial and temporal mechanisms used to regulate such a large array of virulence determinants after they have been delivered into host cells. Here we investigated several L. pneumophila effector proteins that contain a conserved phosphatidylinositol-4-phosphate (PI4P)-binding domain first described in the effector DrrA (SidM). This PI4P binding domain was essential for the localization of effectors to the early L. pneumophila-containing vacuole (LCV), and DrrA-mediated recruitment of Rab1 to the LCV required PI4P-binding activity. It was found that the host cell machinery that regulates sites of contact between the plasma membrane (PM) and the endoplasmic reticulum (ER) modulates PI4P dynamics on the LCV to control localization of these effectors. Specifically, phosphatidylinositol-4-kinase III? (PI4KIII?) was important for generating a PI4P signature that enabled L. pneumophila effectors to localize to the PM-derived vacuole, and the ER-associated phosphatase Sac1 was involved in metabolizing the PI4P on the vacuole to promote the dissociation of effectors. A defect in L. pneumophila replication in macrophages deficient in PI4KIII? was observed, highlighting that a PM-derived PI4P signature is critical for biogenesis of a vacuole that supports intracellular multiplication of L. pneumophila. These data indicate that PI4P metabolism by enzymes controlling PM-ER contact sites regulate the association of L. pneumophila effectors to coordinate early stages of vacuole biogenesis. PMID:24992562

Hubber, Andree; Arasaki, Kohei; Nakatsu, Fubito; Hardiman, Camille; Lambright, David; De Camilli, Pietro; Nagai, Hiroki; Roy, Craig R.

2014-01-01

383

Protecting and rescuing the effectors: roles of differentiation and survival in the control of memory T cell development  

PubMed Central

Vaccines, arguably the single most important intervention in improving human health, have exploited the phenomenon of immunological memory. The elicitation of memory T cells is often an essential part of successful long-lived protective immunity. Our understanding of T cell memory has been greatly aided by the development of TCR Tg mice and MHC tetrameric staining reagents that have allowed the precise tracking of antigen-specific T cell responses. Indeed, following acute infection or immunization, naïve T cells undergo a massive expansion culminating in the generation of a robust effector T cell population. This peak effector response is relatively short-lived and, while most effector T cells die by apoptosis, some remain and develop into memory cells. Although the molecular mechanisms underlying this cell fate decision remain incompletely defined, substantial progress has been made, particularly with regards to CD8+ T cells. For example, the effector CD8+ T cells generated during a response are heterogeneous, consisting of cells with more or less potential to develop into full-fledged memory cells. Development of CD8+ T cell memory is regulated by the transcriptional programs that control the differentiation and survival of effector T cells. While the type of antigenic stimulation and level of inflammation control effector CD8+ T cell differentiation, availability of cytokines and their ability to control expression and function of Bcl-2 family members governs their survival. These distinct differentiation and survival programs may allow for finer therapeutic intervention to control both the quality and quantity of CD8+ T cell memory. Effector to memory transition of CD4+ T cells is less well characterized than CD8+ T cells, emerging details will be discussed. This review will focus on the recent progress made in our understanding of the mechanisms underlying the development of T cell memory with an emphasis on factors controlling survival of effector T cells. PMID:23346085

Kurtulus, Sema; Tripathi, Pulak; Hildeman, David A.

2013-01-01

384

Dormant Intracellular Salmonella enterica Serovar Typhimurium Discriminates among Salmonella Pathogenicity Island 2 Effectors To Persist inside Fibroblasts  

PubMed Central

Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations. PMID:24144726

Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M. Graciela; Casadesús, Josep

2014-01-01

385

Dormant intracellular Salmonella enterica serovar Typhimurium discriminates among Salmonella pathogenicity island 2 effectors to persist inside fibroblasts.  

PubMed

Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations. PMID:24144726

Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M Graciela; Casadesús, Josep; García-del Portillo, Francisco

2014-01-01

386

Comparative Analysis of Type III Secreted Effector Genes Reflects Divergence of Acidovorax citrulli Strains into Three Distinct Lineages.  

PubMed

ABSTRACT Acidovorax citrulli causes bacterial fruit blotch of cucurbits, a serious economic threat to watermelon (Citrullus lanatus) and melon (Cucumis melo) production worldwide. Based on genetic and biochemical traits, A. citrulli strains have been divided into two distinct groups: group I strains have been mainly isolated from various non-watermelon hosts, while group II strains have been generally isolated from and are highly virulent on watermelon. The pathogen depends on a functional type III secretion system for pathogenicity. Annotation of the genome of the group II strain AAC00-1 revealed 11 genes encoding putative type III secreted (T3S) effectors. Due to the crucial role of type III secretion for A. citrulli pathogenicity, we hypothesized that group I and II strains differ in their T3S effector repertoire. Comparative analysis of the 11 effector genes from a collection of 22 A. citrulli strains confirmed this hypothesis. Moreover, this analysis led to the identification of a third A. citrulli group, which was supported by DNA:DNA hybridization, DNA fingerprinting, multilocus sequence analysis of conserved genes, and virulence assays. The effector genes assessed in this study are homologous to effectors from other plant-pathogenic bacteria, mainly belonging to Xanthomonas spp. and Ralstonia solanacearum. Analyses of the effective number of codons and gas chromatography content of effector genes relative to a representative set of housekeeping genes support the idea that these effector genes were acquired by lateral gene transfer. Further investigation is required to identify new T3S effectors of A. citrulli and to determine their contribution to virulence and host preferential association. PMID:24848275

Eckshtain-Levi, Noam; Munitz, Tamar; Zivanovi?, Marija; Traore, Sy M; Spröer, Cathrin; Zhao, Bingyu; Welbaum, Gregory; Walcott, Ron; Sikorski, Johannes; Burdman, Saul

2014-11-01

387

Dynamic analysis of a 6 DOF CKCM robot end-effector for dual-arm telerobot systems  

Microsoft Academic Search

In this paper, we present the dynamical analysis of a six-de- gree-of-freedom robot end-effector built to study telerobotic service and maintenance of NASA hardwares in space. The design of the end-effector is based on the concept of closed- kinematic chain mechanism capable of performing precise motion in a small workspace. After presenting a closed-form solution for the inverse kinematic problem,

Charles C. Nguyen; Farhad J. Pooran

1989-01-01

388

Visual Surround Suppression in Schizophrenia  

PubMed Central

Compared to unaffected observers patients with schizophrenia (SZ) show characteristic differences in visual perception, including a reduced susceptibility to the influence of context on judgments of contrast – a manifestation of weaker surround suppression (SS). To examine the generality of this phenomenon we measured the ability of 24 individuals with SZ to judge the luminance, contrast, orientation, and size of targets embedded in contextual surrounds that would typically influence the target’s appearance. Individuals with SZ demonstrated weaker SS compared to matched controls for stimuli defined by contrast or size, but not for those defined by luminance or orientation. As perceived luminance is thought to be regulated at the earliest stages of visual processing our findings are consistent with a suppression deficit that is predominantly cortical in origin. In addition, we propose that preserved orientation SS in SZ may reflect the sparing of broadly tuned mechanisms of suppression. We attempt to reconcile these data with findings from previous studies. PMID:23450069

Tibber, Marc S.; Anderson, Elaine J.; Bobin, Tracy; Antonova, Elena; Seabright, Alice; Wright, Bernice; Carlin, Patricia; Shergill, Sukhwinder S.; Dakin, Steven C.

2013-01-01

389

Vibration suppression using smart structures  

NASA Technical Reports Server (NTRS)

The control of structures for vibration suppression is discussed in the context of using smart materials and structures. Here the use of smart structures refers to using embedded piezoelectric devices as both control actuators and sensors. Using embedded sensors and actuators allows great improvements in performance over traditional structures (both passive and active) for vibration suppression. The application of smart structures to three experimental flexible structures is presented. The first is a flexible beam, the second is a flexible beam undergoing slewing motion, the third is a ribbed antenna. A simple model of a piezoelectric actuator/sensor is presented. The equations of motion for each structure is presented. The control issues considered as those associated with multi-input, multi-output control, PID control and LQR control implementation. A modern control analysis illustrates the usefulness of smart structures for vibration suppression.

Garcia, Ephrahim; Inman, Daniel J.; Dosch, Jeffrey

1991-01-01

390

Epigenetic control of effector gene expression in the plant pathogenic fungus Leptosphaeria maculans.  

PubMed

Plant pathogens secrete an arsenal of small secreted proteins (SSPs) acting as effectors that modulate host immunity to facilitate infection. SSP-encoding genes are often located in particular genomic environments and show waves of concerted expression at diverse stages of plant infection. To date, little is known about the regulation of their expression. The genome of the Ascomycete Leptosphaeria maculans comprises alternating gene-rich GC-isochores and gene-poor AT-isochores. The AT-isochores harbor mosaics of transposable elements, encompassing one-third of the genome, and are enriched in putative effector genes that present similar expression patterns, namely no expression or low-level expression during axenic cultures compared to strong induction of expression during primary infection of oilseed rape (Brassica napus). Here, we investigated the involvement of one specific histone modification, histone H3 lysine 9 methylation (H3K9me3), in epigenetic regulation of concerted effector gene expression in L. maculans. For this purpose, we silenced the expression of two key players in heterochromatin assembly and maintenance, HP1 and DIM-5 by RNAi. By using HP1-GFP as a heterochromatin marker, we observed that almost no chromatin condensation is visible in strains in which LmDIM5 was silenced by RNAi. By whole genome oligoarrays we observed overexpression of 369 or 390 genes, respectively, in the silenced-LmHP1 and -LmDIM5 transformants during growth in axenic culture, clearly favouring expression of SSP-encoding genes within AT-isochores. The ectopic integration of four effector genes in GC-isochores led to their overexpression during growth in axenic culture. These data strongly suggest that epigenetic control, mediated by HP1 and DIM-5, represses the expression of at least part of the effector genes located in AT-isochores during growth in axenic culture. Our hypothesis is that changes of lifestyle and a switch toward pathogenesis lift chromatin-mediated repression, allowing a rapid response to new environmental conditions. PMID:24603691

Soyer, Jessica L; El Ghalid, Mennat; Glaser, Nicolas; Ollivier, Bénédicte; Linglin, Juliette; Grandaubert, Jonathan; Balesdent, Marie-Hélène; Connolly, Lanelle R; Freitag, Michael; Rouxel, Thierry; Fudal, Isabelle

2014-03-01

391

Epigenetic Control of Effector Gene Expression in the Plant Pathogenic Fungus Leptosphaeria maculans  

PubMed Central

Plant pathogens secrete an arsenal of small secreted proteins (SSPs) acting as effectors that modulate host immunity to facilitate infection. SSP-encoding genes are often located in particular genomic environments and show waves of concerted expression at diverse stages of plant infection. To date, little is known about the regulation of their expression. The genome of the Ascomycete Leptosphaeria maculans comprises alternating gene-rich GC-isochores and gene-poor AT-isochores. The AT-isochores harbor mosaics of transposable elements, encompassing one-third of the genome, and are enriched in putative effector genes that present similar expression patterns, namely no expression or low-level expression during axenic cultures compared to strong induction of expression during primary infection of oilseed rape (Brassica napus). Here, we investigated the involvement of one specific histone modification, histone H3 lysine 9 methylation (H3K9me3), in epigenetic regulation of concerted effector gene expression in L. maculans. For this purpose, we silenced the expression of two key players in heterochromatin assembly and maintenance, HP1 and DIM-5 by RNAi. By using HP1-GFP as a heterochromatin marker, we observed that almost no chromatin condensation is visible in strains in which LmDIM5 was silenced by RNAi. By whole genome oligoarrays we observed overexpression of 369 or 390 genes, respectively, in the silenced-LmHP1 and -LmDIM5 transformants during growth in axenic culture, clearly favouring expression of SSP-encoding genes within AT-isochores. The ectopic integration of four effector genes in GC-isochores led to their overexpression during growth in axenic culture. These data strongly suggest that epigenetic control, mediated by HP1 and DIM-5, represses the expression of at least part of the effector genes located in AT-isochores during growth in axenic culture. Our hypothesis is that changes of lifestyle and a switch toward pathogenesis lift chromatin-mediated repression, allowing a rapid response to new environmental conditions. PMID:24603691

Soyer, Jessica L.; El Ghalid, Mennat; Glaser, Nicolas; Ollivier, Bénédicte; Linglin, Juliette; Grandaubert, Jonathan; Balesdent, Marie-Hélène; Connolly, Lanelle R.; Freitag, Michael; Rouxel, Thierry; Fudal, Isabelle

2014-01-01

392

A Translocated Effector Required for Bartonella Dissemination from Derma to Blood Safeguards Migratory Host Cells from Damage by Co-translocated Effectors  

PubMed Central

Numerous bacterial pathogens secrete multiple effectors to modulate host cellular functions. These effectors may interfere with each other to efficiently control the infection process. Bartonellae are Gram-negative, facultative intracellular bacteria using a VirB type IV secretion system to translocate a cocktail of Bartonella effector proteins (Beps) into host cells. Based on in vitro infection models we demonstrate here that BepE protects infected migratory cells from injurious effects triggered by BepC and is required for in vivo dissemination of bacteria from the dermal site of inoculation to blood. Human endothelial cells (HUVECs) infected with a ?bepE mutant of B. henselae (Bhe) displayed a cell fragmentation phenotype resulting from Bep-dependent disturbance of rear edge detachment during migration. A ?bepCE mutant did not show cell fragmentation, indicating that BepC is critical for triggering this deleterious phenotype. Complementation of ?bepE with BepEBhe or its homologues from other Bartonella species abolished cell fragmentation. This cyto-protective activity is confined to the C-terminal Bartonella intracellular delivery (BID) domain of BepEBhe (BID2.EBhe). Ectopic expression of BID2.EBhe impeded the disruption of actin stress fibers by Rho Inhibitor 1, indicating that BepE restores normal cell migration via the RhoA signaling pathway, a major regulator of rear edge retraction. An intradermal (i.d.) model for B. tribocorum (Btr) infection in the rat reservoir host mimicking the natural route of infection by blood sucking arthropods allowed demonstrating a vital role for BepE in bacterial dissemination from derma to blood. While the Btr mutant ?bepDE was abacteremic following i.d. inoculation, complementation with BepEBtr, BepEBhe or BIDs.EBhe restored bacteremia. Given that we observed a similar protective effect of BepEBhe on infected bone marrow-derived dendritic cells migrating through a monolayer of lymphatic endothelial cells we propose that infected dermal dendritic cells may be involved in disseminating Bartonella towards the blood stream in a BepE-dependent manner. PMID:24945914

Okujava, Rusudan; Guye, Patrick; Lu, Yun-Yueh; Mistl, Claudia; Polus, Florine; Vayssier-Taussat, Muriel; Halin, Cornelia; Rolink, Antonius G.; Dehio, Christoph

2014-01-01

393

Effectors of root sedentary nematodes target diverse plant cell compartments to manipulate plant functions and promote infection  

PubMed Central

Sedentary plant-parasitic nematodes maintain a biotrophic relationship with their hosts over a period of several weeks and induce the differentiation of root cells into specialized feeding cells. Nematode effectors, which are synthesized in the esophageal glands and injected into the plant tissue through the syringe-like stylet, play a central role in these processes. Previous work on nematode effectors has shown that the apoplasm is targeted during invasion of the host while the cytoplasm is targeted during the induction and the maintenance of the feeding site. A large number of candidate effectors potentially secreted by the nematode into the plant tissues to promote infection have now been identified. This work has shown that the targeting and the role of effectors are more complex than previously thought. This review will not cover the prolific recent findings in nematode effector function but will instead focus on recent selected examples that illustrate the variety of plant cell compartments that effectors are addressed to in order reach their plant targets. PMID:23857349

Jaouannet, Maëlle; Rosso, Marie-Noëlle

2013-01-01

394

Phytoplasma Effector SAP54 Induces Indeterminate Leaf-Like Flower Development in Arabidopsis Plants1[C][W][OA  

PubMed Central

Phytoplasmas are insect-transmitted bacterial plant pathogens that cause considerable damage to a diverse range of agricultural crops globally. Symptoms induced in infected plants suggest that these phytopathogens may modulate developmental processes within the plant host. We report herein that Aster Yellows phytoplasma strain Witches’ Broom (AY-WB) readily infects the model plant Arabidopsis (Arabidopsis thaliana) ecotype Columbia, inducing symptoms that are characteristic of phytoplasma infection, such as the production of green leaf-like flowers (virescence and phyllody) and increased formation of stems and branches (witches’ broom). We found that the majority of genes encoding secreted AY-WB proteins (SAPs), which are candidate effector proteins, are expressed in Arabidopsis and the AY-WB insect vector Macrosteles quadrilineatus (Hemiptera; Cicadellidae). To identify which of these effector proteins induce symptoms of phyllody and virescence, we individually expressed the effector genes in Arabidopsis. From this screen, we have identified a novel AY-WB effector protein, SAP54, that alters floral development, resulting in the production of leaf-like flowers that are similar to those produced by plants infected with this phytoplasma. This study offers novel insight into the effector profile of an insect-transmitted plant pathogen and reports to our knowledge the first example of a microbial pathogen effector protein that targets flower development in a host. PMID:21849514

MacLean, Allyson M.; Sugio, Akiko; Makarova, Olga V.; Findlay, Kim C.; Grieve, Victoria M.; Tóth, Réka; Nicolaisen, Mogens; Hogenhout, Saskia A.

2011-01-01

395

OX40 controls effector CD4+ T-cell expansion, not follicular T helper cell generation in acute Listeria infection  

PubMed Central

To investigate the importance of OX40 signals for physiological CD4+ T-cell responses, an endogenous antigen-specific population of CD4+ T cells that recognise the 2W1S peptide was assessed and temporal control of OX40 signals was achieved using blocking or agonistic antibodies (Abs) in vivo. Following infection with Listeria monocytogenes expressing 2W1S peptide, OX40 was briefly expressed by the responding 2W1S-specific CD4+ T cells, but only on a subset that co-expressed effector cell markers. This population was specifically expanded by Ab-ligation of OX40 during priming, which also caused skewing of the memory response towards effector memory cells. Strikingly, this greatly enhanced effector response was accompanied by the loss of T follicular helper (TFH) cells and germinal centres. Mice deficient in OX40 and CD30 showed normal generation of TFH cells but impaired numbers of 2W1S-specific effector cells. OX40 was not expressed by 2W1S-specific memory cells, although it was rapidly up-regulated upon challenge whereupon Ab-ligation of OX40 specifically affected the effector subset. In summary, these data indicate that for CD4+ T cells, OX40 signals are important for generation of effector T cells rather than TFH cells in this response to acute bacterial infection. PMID:24771127

Marriott, Clare L; Mackley, Emma C; Ferreira, Cristina; Veldhoen, Marc; Yagita, Hideo; Withers, David R

2014-01-01

396

Suppression of BMP-Smad signaling axis-induced osteoblastic differentiation by small C-terminal domain phosphatase 1, a Smad phosphatase.  

PubMed

Bone morphogenetic proteins (BMPs) induce osteoblastic differentiation in myogenic cells via the phosphorylation of Smads. Two types of Smad phosphatases--small C-terminal domain phosphatase 1 (SCP1) and protein phosphatase magnesium-dependent 1A--have been shown to inhibit BMP activity. Here, we report that SCP1 inhibits the osteoblastic differentiation induced by BMP-4, a constitutively active BMP receptor, and a constitutively active form of Smad1. The phosphatase activity of SCP1 was required for this suppression, and the knockdown of SCP1 in myoblasts stimulated the osteoblastic differentiation induced by BMP signaling. In contrast to protein phosphatase magnesium-dependent 1A, SCP1 did not reduce the protein levels of Smad1 and failed to suppress expression of the Id1, Id2, and Id3 genes. Runx2-induced osteoblastic differentiation was suppressed by SCP1 without affecting the transcriptional activity or phosphorylation levels of Runx2. Taken together, these findings suggest that SCP1 may inhibit the osteoblastic differentiation induced by the BMP-Smad axis via Runx2 by suppressing downstream effector(s). PMID:21239611

Kokabu, Shoichiro; Ohte, Satoshi; Sasanuma, Hiroki; Shin, Masashi; Yoneyama, Katsumi; Murata, Eiko; Kanomata, Kazuhiro; Nojima, Junya; Ono, Yusuke; Yoda, Tetsuya; Fukuda, Toru; Katagiri, Takenobu

2011-03-01

397

Noise suppressing capillary separation system  

DOEpatents

A noise-suppressing capillary separation system for detecting the real-time presence or concentration of an analyte in a sample is provided. The system contains a capillary separation means through which the analyte is moved, a coherent light source that generates a beam which is split into a reference beam and a sample beam that irradiate the capillary, and a detector for detecting the reference beam and the sample beam light that transmits through the capillary. The laser beam is of a wavelength effective to be absorbed by a chromophore in the capillary. The system includes a noise suppressing system to improve performance and accuracy without signal averaging or multiple scans.

Yeung, Edward S. (Ames, IA); Xue, Yongjun (Norwich, NY)

1996-07-30

398

Comparative Large-Scale Analysis of Interactions between Several Crop Species and the Effector Repertoires from Multiple Pathovars of Pseudomonas and Ralstonia1[W][OA  

PubMed Central

Bacterial plant pathogens manipulate their hosts by injection of numerous effector proteins into host cells via type III secretion systems. Recognition of these effectors by the host plant leads to the induction of a defense reaction that often culminates in a hypersensitive response manifested as cell death. Genes encoding effector proteins can be exchanged between different strains of bacteria via horizontal transfer, and often individual strains are capable of infecting multiple hosts. Host plant species express diverse repertoires of resistance proteins that mediate direct or indirect recognition of bacterial effectors. As a result, plants and their bacterial pathogens should be considered as two extensive coevolving groups rather than as individual host species coevolving with single pathovars. To dissect the complexity of this coevolution, we cloned 171 effector-encoding genes from several pathovars of Pseudomonas and Ralstonia. We used Agrobacterium tumefaciens-mediated transient assays to test the ability of each effector to induce a necrotic phenotype on 59 plant genotypes belonging to four plant families, including numerous diverse accessions of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum). Known defense-inducing effectors (avirulence factors) and their homologs commonly induced extensive necrosis in many different plant species. Nonhost species reacted to multiple effector proteins from an individual pathovar more frequently and more intensely than host species. Both homologous and sequence-unrelated effectors could elicit necrosis in a similar spectrum of plants, suggesting common effector targets or targeting of the same pathways in the plant cell. PMID:19571308

Wroblewski, Tadeusz; Caldwell, Katherine S.; Piskurewicz, Urszula; Cavanaugh, Keri A.; Xu, Huaqin; Kozik, Alexander; Ochoa, Oswaldo; McHale, Leah K.; Lahre, Kirsten; Jelenska, Joanna; Castillo, Jose A.; Blumenthal, Daniel; Vinatzer, Boris A.; Greenberg, Jean T.; Michelmore, Richard W.

2009-01-01

399

DENDRITIC POLYMERS AS FIRE SUPPRESSANTS  

EPA Science Inventory

This report describes an evaluation of the applicability of one of the latest advances in polymer technology (dendritic polymers) to suppressing fires, one of the greatest survivability threats to military personnel and vehicles. Certain types of alkali and transition metal compl...

400

Fermionic Suppression of Dipolar Relaxation  

NASA Astrophysics Data System (ADS)

We observe the suppression of inelastic dipolar scattering in ultracold Fermi gases of the highly magnetic atom dysprosium: the more energy that is released, the less frequently these exothermic reactions take place, and only quantum spin statistics can explain this counterintuitive effect. Inelastic dipolar scattering in nonzero magnetic fields leads to heating or to loss of the trapped population, both detrimental to experiments intended to study quantum many-body physics with strongly dipolar gases. Fermi statistics, however, is predicted to lead to a kinematic suppression of these harmful reactions. Indeed, we observe a 120-fold suppression of dipolar relaxation in fermionic versus bosonic Dy, as expected from theory describing universal inelastic dipolar scattering, though never before experimentally confirmed. Similarly, low inelastic cross sections are observed in spin mixtures, also with striking correspondence to predictions. The suppression of relaxation opens the possibility of employing fermionic dipolar species in studies of quantum many-body physics involving, e.g., synthetic gauge fields and pairing.

Burdick, Nathaniel Q.; Baumann, Kristian; Tang, Yijun; Lu, Mingwu; Lev, Benjamin L.

2015-01-01

401

Fermionic suppression of dipolar relaxation.  

PubMed

We observe the suppression of inelastic dipolar scattering in ultracold Fermi gases of the highly magnetic atom dysprosium: the more energy that is released, the less frequently these exothermic reactions take place, and only quantum spin statistics can explain this counterintuitive effect. Inelastic dipolar scattering in nonzero magnetic fields leads to heating or to loss of the trapped population, both detrimental to experiments intended to study quantum many-body physics with strongly dipolar gases. Fermi statistics, however, is predicted to lead to a kinematic suppression of these harmful reactions. Indeed, we observe a 120-fold suppression of dipolar relaxation in fermionic versus bosonic Dy, as expected from theory describing universal inelastic dipolar scattering, though never before experimentally confirmed. Similarly, low inelastic cross sections are observed in spin mixtures, also with striking correspondence to predictions. The suppression of relaxation opens the possibility of employing fermionic dipolar species in studies of quantum many-body physics involving, e.g., synthetic gauge fields and pairing. PMID:25635544

Burdick, Nathaniel Q; Baumann, Kristian; Tang, Yijun; Lu, Mingwu; Lev, Benjamin L

2015-01-16

402

Sex determination: switch and suppress.  

PubMed

The transcription factor Dmrt1 regulates male sexual development from flies and worms to humans. A newly discovered function is to suppress female differentiation in the testes. Thus, the gonadal fate decision is not final but has to be actively maintained throughout life. PMID:21920296

Herpin, Amaury; Schartl, Manfred

2011-09-13