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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.

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.  

PubMed

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; however, TFT1's role in PTI and/or XopN virulence was not determined. Here we show that TFT1 functions in PTI and is a XopN virulence target. Virus-induced gene silencing of TFT1 mRNA in tomato leaves resulted in increased growth of Xcv ?xopN and Xcv ?hrpF demonstrating that TFT1 is required to inhibit Xcv multiplication. TFT1 expression was required for Xcv-induced accumulation of PTI5, GRAS4, WRKY28, and LRR22 mRNAs, four PTI marker genes in tomato. Deletion analysis revealed that the XopN C-terminal domain (amino acids 344-733) is sufficient to bind TFT1. Removal of amino acids 605-733 disrupts XopN binding to TFT1 in plant extracts and inhibits XopN-dependent virulence in tomato, demonstrating that these residues are necessary for the XopN/TFT1 interaction. Phos-tag gel analysis and mass spectrometry showed that XopN is phosphorylated in plant extracts at serine 688 in a putative 14-3-3 recognition motif. Mutation of S688 reduced XopN's phosphorylation state but was not sufficient to inhibit binding to TFT1 or reduce XopN virulence. Mutation of S688 and two leucines (L64,L65) in XopN, however, eliminated XopN binding to TFT1 in plant extracts and XopN virulence. L64 and L65 are required for XopN to bind TARK1, a tomato atypical receptor kinase required for PTI. This suggested that TFT1 binding to XopN's C-terminal domain might be stabilized via TARK1/XopN interaction. Pull-down and BiFC analyses show that XopN promotes TARK1/TFT1 complex formation in vitro and in planta by functioning as a molecular scaffold. This is the first report showing that a type III effector targets a host 14-3-3 involved in PTI to promote bacterial pathogenesis. PMID:22719257

Taylor, Kyle W; Kim, Jung-Gun; Su, Xue B; Aakre, Chris D; Roden, Julie A; Adams, Christopher M; Mudgett, Mary Beth

2012-06-14

3

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

PubMed Central

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; however, TFT1's role in PTI and/or XopN virulence was not determined. Here we show that TFT1 functions in PTI and is a XopN virulence target. Virus-induced gene silencing of TFT1 mRNA in tomato leaves resulted in increased growth of Xcv ?xopN and Xcv ?hrpF demonstrating that TFT1 is required to inhibit Xcv multiplication. TFT1 expression was required for Xcv-induced accumulation of PTI5, GRAS4, WRKY28, and LRR22 mRNAs, four PTI marker genes in tomato. Deletion analysis revealed that the XopN C-terminal domain (amino acids 344–733) is sufficient to bind TFT1. Removal of amino acids 605–733 disrupts XopN binding to TFT1 in plant extracts and inhibits XopN-dependent virulence in tomato, demonstrating that these residues are necessary for the XopN/TFT1 interaction. Phos-tag gel analysis and mass spectrometry showed that XopN is phosphorylated in plant extracts at serine 688 in a putative 14-3-3 recognition motif. Mutation of S688 reduced XopN's phosphorylation state but was not sufficient to inhibit binding to TFT1 or reduce XopN virulence. Mutation of S688 and two leucines (L64,L65) in XopN, however, eliminated XopN binding to TFT1 in plant extracts and XopN virulence. L64 and L65 are required for XopN to bind TARK1, a tomato atypical receptor kinase required for PTI. This suggested that TFT1 binding to XopN's C-terminal domain might be stabilized via TARK1/XopN interaction. Pull-down and BiFC analyses show that XopN promotes TARK1/TFT1 complex formation in vitro and in planta by functioning as a molecular scaffold. This is the first report showing that a type III effector targets a host 14-3-3 involved in PTI to promote bacterial pathogenesis.

Su, Xue B.; Aakre, Chris D.; Roden, Julie A.; Adams, Christopher M.; Mudgett, Mary Beth

2012-01-01

4

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.

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

2013-01-01

5

Suppression of HIV-1 replication by microRNA effectors.  

PubMed

The rate of HIV-1 gene expression is a key step that determines the kinetics of virus spread and AIDS progression. Viral entry and gene expression were described to be the key determinants for cell permissiveness to HIV. Recent reports highlighted the involvement of miRNA in regulating HIV-1 replication post-transcriptionally. In this study we explored the role of cellular factors required for miRNA-mediated mRNA translational inhibition in regulating HIV-1 gene expression. Here we show that HIV-1 mRNAs associate and co-localize with components of the RNA Induced Silencing Complex (RISC), and we characterize some of the proteins required for miRNA-mediated silencing (miRNA effectors). RCK/p54, GW182, LSm-1 and XRN1 negatively regulate HIV-1 gene expression by preventing viral mRNA association with polysomes. Interestingly, knockdown of RCK/p54 or DGCR8 resulted in virus reactivation in PBMCs isolated from HIV infected patients treated with suppressive HAART. PMID:19272132

Chable-Bessia, Christine; Meziane, Oussama; Latreille, Daniel; Triboulet, Robinson; Zamborlini, Alessia; Wagschal, Alexandre; Jacquet, Jean-Marc; Reynes, Jacques; Levy, Yves; Saib, Ali; Bennasser, Yamina; Benkirane, Monsef

2009-03-09

6

Suppression of HIV-1 replication by microRNA effectors  

PubMed Central

The rate of HIV-1 gene expression is a key step that determines the kinetics of virus spread and AIDS progression. Viral entry and gene expression were described to be the key determinants for cell permissiveness to HIV. Recent reports highlighted the involvement of miRNA in regulating HIV-1 replication post-transcriptionally. In this study we explored the role of cellular factors required for miRNA-mediated mRNA translational inhibition in regulating HIV-1 gene expression. Here we show that HIV-1 mRNAs associate and co-localize with components of the RNA Induced Silencing Complex (RISC), and we characterize some of the proteins required for miRNA-mediated silencing (miRNA effectors). RCK/p54, GW182, LSm-1 and XRN1 negatively regulate HIV-1 gene expression by preventing viral mRNA association with polysomes. Interestingly, knockdown of RCK/p54 or DGCR8 resulted in virus reactivation in PBMCs isolated from HIV infected patients treated with suppressive HAART.

Chable-Bessia, Christine; Meziane, Oussama; Latreille, Daniel; Triboulet, Robinson; Zamborlini, Alessia; Wagschal, Alexandre; Jacquet, Jean-Marc; Reynes, Jacques; Levy, Yves; Saib, Ali; Bennasser, Yamina; Benkirane, Monsef

2009-01-01

7

Bacterial effector HopF2 interacts with AvrPto and suppresses Arabidopsis innate immunity at the plasma membrane  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plant pathogenic bacteria inject a cocktail of effector proteins into host plant cells to modulate the host immune response, thereby promoting pathogenicity. How or whether these effectors work cooperatively is largely unknown. The Pseudomonas syringae DC3000 effector HopF2 suppresses the host plan...

8

Lipoteichoic acid suppresses effector T cells induced by staphylococcus aureus-pulsed dendritic cells.  

PubMed

Lipoteichoic acid (LTA), uniquely expressed on gram-positive bacteria, is recognized by Tolllike receptor 2 (TLR2) on not only antigen-presenting cells but also activated T cells. Therefore, it is reasonable to assume that LTA is acting on T cells. However, little is known about the effect of LTA on T-cell regulation. In the present study, we investigated the immunomodulatory effects of LTA on CD4? T cells. Effector CD4? T cells, induced after co-culture with S. aureuspulsed dendritic cells, produced high levels of interferon-?, CD25, CD69, and TLRs 2 and 4. When effector CD4? T cells were treated with LTA, the expressions of the membrane-bound form of transforming growth factor (TGF)-? and forkhead box P3 increased. Coincidently, the proliferation of effector CD4? T cells was declined after LTA treatment. When TGF-? signaling was blocked by the TGF-? receptor 1 kinase inhibitor, LTA failed to suppress the proliferation of effector CD4? T cells. Therefore, the present results suggest that LTA suppresses the activity of effector CD4? T cells by enhancing TGF-? production. PMID:23727812

Son, Young Min; Song, Ki-Duk; Park, Sung-Moo; Han, Seung Hyun; Yun, Cheol-Heui

2013-07-28

9

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

2013-06-10

10

Regulatory T cells reversibly suppress cytotoxic T cell function independent of effector differentiation.  

PubMed

Mechanisms of dominant tolerance have evolved within the mammalian immune system to prevent inappropriate immune responses. CD4(+)CD25(+) regulatory T (T(reg)) cells have emerged as central constituents of this suppressive activity. By using multiphoton intravital microscopy in lymph nodes (LNs) of anesthetized mice, we have analyzed how cytotoxic T lymphocytes (CTLs) interact with antigen-presenting target cells in the presence or absence of activated T(reg) cells. Nonregulated CTLs killed their targets at a 6.6-fold faster rate than regulated CTLs. In spite of this compromised effector activity, regulated CTLs exhibited no defect in proliferation, induction of cytotoxic effector molecules and secretory granules, in situ motility, or ability to form antigen-dependent conjugates with target cells. Only granule exocytosis by CTLs was markedly impaired in the presence of T(reg) cells. This selective form of regulation did not require prolonged contact between CTLs and T(reg) cells but depended on CTL responsiveness to transforming growth factor-beta. CTLs quickly regained full killing capacity in LNs upon selective removal of T(reg) cells. Thus, T(reg) cells reversibly suppress CTL-mediated immunity by allowing acquisition of full effector potential but withholding the license to kill. PMID:16860762

Mempel, Thorsten R; Pittet, Mikael J; Khazaie, Khashayarsha; Weninger, Wolfgang; Weissleder, Ralph; von Boehmer, Harald; von Andrian, Ulrich H

2006-07-01

11

The Ustilago maydis Effector Pep1 Suppresses Plant Immunity by Inhibition of Host Peroxidase Activity  

PubMed Central

The corn smut Ustilago maydis establishes a biotrophic interaction with its host plant maize. This interaction requires efficient suppression of plant immune responses, which is attributed to secreted effector proteins. Previously we identified Pep1 (Protein essential during penetration-1) as a secreted effector with an essential role for U. maydis virulence. pep1 deletion mutants induce strong defense responses leading to an early block in pathogenic development of the fungus. Using cytological and functional assays we show that Pep1 functions as an inhibitor of plant peroxidases. At sites of ?pep1 mutant penetrations, H2O2 strongly accumulated in the cell walls, coinciding with a transcriptional induction of the secreted maize peroxidase POX12. Pep1 protein effectively inhibited the peroxidase driven oxidative burst and thereby suppresses the early immune responses of maize. Moreover, Pep1 directly inhibits peroxidases in vitro in a concentration-dependent manner. Using fluorescence complementation assays, we observed a direct interaction of Pep1 and the maize peroxidase POX12 in vivo. Functional relevance of this interaction was demonstrated by partial complementation of the ?pep1 mutant defect by virus induced gene silencing of maize POX12. We conclude that Pep1 acts as a potent suppressor of early plant defenses by inhibition of peroxidase activity. Thus, it represents a novel strategy for establishing a biotrophic interaction.

Zechmann, Bernd; Hillmer, Morten; Doehlemann, Gunther

2012-01-01

12

Ultraviolet B Suppresses Immunity by Inhibiting Effector and Memory T Cells  

PubMed Central

Contact hypersensitivity is a T-cell-mediated response to a hapten. Exposing C57BL/6 mice to UV B radiation systemically suppresses both primary and secondary contact hypersensitivity responses. The effects of UVB on in vivo T-cell responses during UVB-induced immunosuppression are unknown. We show here that UVB exposure, before contact sensitization, inhibits the expansion of effector CD4+ and CD8+ T cells in skin-draining lymph nodes and reduces the number of CD4+ and IFN-?+ CD8+ T cells infiltrating challenged ear skin. In the absence of UVB, at 10 weeks after initial hapten exposure, the ear skin of sensitized mice was infiltrated by dermal effector memory CD8+ T cells at the site of challenge. However, if mice were previously exposed to UVB, this cell population was absent, suggesting an impaired development of peripheral memory T cells. This finding occurred in the absence of UVB-induced regulatory CD4+ T cells and did not involve prostaglandin E2, suggesting that the importance of these two factors in mediating or initiating UVB-induced immunosuppression is dependent on UVB dose. Together these data indicate that in vivo T-cell responses are prone to immunoregulation by UVB, including a novel effect on both the activated T-cell pool size and the development of memory T cells in peripheral compartments.

Rana, Sabita; Byrne, Scott Napier; MacDonald, Linda Joanne; Chan, Carling Yan-Yan; Halliday, Gary Mark

2008-01-01

13

Identification of a novel effector domain of BIN1 for cancer suppression  

PubMed Central

Bridging integrator 1 (BIN1) is a nucleocytoplasmic adaptor protein with tumor suppressor properties. The protein interacts with and inhibits the c-MYC transcription factor through the BIN1 MYC-binding domain (MBD). However, in vitro colony formation assays have clearly demonstrated that the MBD is not essential for BIN1-mediated growth arrest. We hypothesized that BIN1 contains a MYC-independent effector domain (MID) for cancer suppression. Because a functionally unique domain frequently contains a distinct structure, the human full-length BIN1 protein was subjected to limited trypsin digestion and the digested peptides were analyzed with Edman sequencing and mass spectrometry. We identified a trypsin-resistant peptide that corresponds to amino acids 146–268 of BIN1. It encompassed part of the BAR region, a putative effector region of BIN1. Computational analysis predicted that the peptide is very likely to exhibit coiled-coil motifs, implying a potential role for this region in sustaining the BIN1 structure and function. Like MBD-deleted BIN1, the trypsin-resistant peptide of BIN1 was predominantly present in the cytoplasm and was sufficient to inhibit cancer growth, regardless of dysregulated c-MYC activity. Our results suggest that the coiled-coil BIN1 BAR peptide encodes a novel BIN1 MID domain, through which BIN1 acts as a MYC-independent cancer suppressor.

Lundgaard, Greta L.; Daniels, Natae E.; Pyndiah, Slovenie; Cassimere, Erica K.; Ahmed, Kazi M.; Rodrigue, Amelie; Kihara, Daisuke; Post, Carol B.; Sakamuro, Daitoku

2011-01-01

14

Erwinia amylovora effector protein Eop1 suppresses PAMP-triggered immunity in Malus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Erwinia amylovora (Ea) utilizes a type three secretion system (T3SS) to deliver effector proteins into plant host cells. Several Ea effectors have been identified based on their sequence similarity to plant and animal bacterial pathogen effectors; however, the function of the majority of Ea effecto...

15

Escape from suppression: tumor-specific effector cells outcompete regulatory T cells following stem-cell transplantation  

PubMed Central

Immune reconstitution of autologous hematopoietic stem-cell transplant recipients with the progeny of mature T cells in the graft leads to profound changes in the emerging functional T-cell repertoire. In the steady state, the host is frequently tolerant to tumor antigens, reflecting dominant suppression of naive and effector T cells by regulatory T cells (Tregs). We examined the relative frequency and function of these 3 components within the tumor-specific T-cell compartment during immune reconstitution. Grafts from tumor-bearing donors exerted a significant antitumor effect in irradiated, syngeneic tumor-bearing recipients. This was associated with dramatic clonal expansion and interferon-? (IFN?) production by previously tolerant tumor-specific T cells. While donor-derived Tregs expanded in recipients, they did not inhibit the antigen-driven expansion of effector T cells in the early posttransplantation period. Indeed, the repopulation of tumor-specific effector T cells significantly exceeded that of Tregs, the expansion of which was limited by IL-2 availability. Although the intrinsic suppressive capacity of Tregs remained intact, their diminished frequency was insufficient to suppress effector cell function. These findings provide an explanation for the reversal of tolerance leading to tumor rejection in transplant recipients and likely contribute to the efficacy of adoptive T-cell therapies in lymphopenic hosts.

Mirmonsef, Paria; Tan, Gladys; Zhou, Gang; Morino, Tricia; Noonan, Kimberly; Borrello, Ivan

2008-01-01

16

Molecular determinants of resistance activation and suppression by Phytophthora infestans effector IPI-O  

Technology Transfer Automated Retrieval System (TEKTRAN)

The potato late blight pathogen, Phytophthora infestans, is able to rapidly evolve to overcome resistance genes. The pathogen accomplishes this by secreting an arsenal of proteins, termed effectors, that function to modify host cells. Although hundreds of candidate effectors have been identified in ...

17

Ubc13 maintains the suppressive function of regulatory T cells and prevents their conversion into effector-like T cells  

PubMed Central

Maintenance of immune homeostasis requires regulatory T (Treg) cells. Here we show that Treg-specific ablation of Ubc13, a lysine 63-specific ubiquitin-conjugating enzyme, caused aberrant T cell activation and autoimmunity. Although Ubc13 deficiency did not affect Treg cell survival or Foxp3 expression, it impaired the in vivo suppressive function of Treg cells and rendered them sensitive for acquiring T helper (TH) 1- and TH17-like effector T cell phenotypes. This function of Ubc13 involved its downstream target, I?B kinase (IKK). The Ubc13-IKK signaling axis controlled the expression specific Treg effector molecules, including interleukin 10 (IL-10) and SOCS1. Collectively, these findings suggest that the Ubc13-IKK signaling axis regulates the molecular program that maintains Treg function and prevents Treg cells from acquiring inflammatory phenotypes.

Chang, Jae-Hoon; Xiao, Yichuan; Hu, Hongbo; Jin, Jin; Yu, Jiayi; Zhou, Xiaofei; Wu, Xuefeng; Johnson, Howard M; Akira, Shizuo; Pasparakis, Manolis; Cheng, Xuhong; Sun, Shao-Cong

2012-01-01

18

Ganglioside GM1 Deficiency in Effector T Cells From NOD Mice Induces Resistance to Regulatory T-Cell Suppression  

PubMed Central

OBJECTIVE To detect GM1 deficiency and determine its role in effector T cells (Teffs) from NOD mice in establishing resistance to regulatory T-cell (Treg) suppression. RESEARCH DESIGN AND METHODS CD4+ and CD8+ Teffs were isolated from spleens of prediabetic NOD mice for comparison with similar cells from Balb/c, C57BL/6, and NOR mice. GM1 was quantified with thin-layer chromatography for total cellular GM1 and flow cytometry for cell-surface GM1. Suppression of Teff proliferation was determined by application of GM1 cross-linking agents or coculturing with Tregs. Calcium influx in Teffs was quantified using fura-2. RESULTS Resting and activated CD4+ and CD8+ Teffs of NOD mice contained significantly less GM1 than Teffs from the other three mouse strains tested. After activation, NOD Teffs resisted suppression by Tregs or GM1 cross-linking agents in contrast to robust suppression of Balb/c Teffs; this was reversed by preincubation of NOD Teffs with GM1. NOD Teffs also showed attenuated Ca2+ influx via transient receptor potential channel 5 (TRPC5) channels induced by GM1 cross-linking, and this, too, was reversed by elevation of Teff GM1. CONCLUSIONS GM1 deficiency occurs in NOD Teffs and contributes importantly to failed suppression, which is rectified by increasing Teff GM1. Such elevation also reverses subthreshold Ca2+ influx via TRPC5 channels, an essential aspect of suppression. Our results also support a critical role for galectin-1 as a GM1 cross-linking counter-receptor that fittingly is upregulated and released by Tregs during activation. These findings suggest a novel mechanism by which pathogenic Teffs evade regulatory suppression, thereby leading to autoimmune ?-cell destruction and type 1 diabetes.

Wu, Gusheng; Lu, Zi-Hua; Gabius, Hans-Joachim; Ledeen, Robert W.; Bleich, David

2011-01-01

19

Vibrio parahaemolyticus Effector Proteins Suppress Inflammasome Activation by Interfering with Host Autophagy Signaling  

PubMed Central

Bacterial pathogens utilize pore-forming toxins or sophisticated secretion systems to establish infection in hosts. Recognition of these toxins or secretion system by nucleotide-binding oligomerization domain leucine-rich repeat proteins (NLRs) triggers the assembly of inflammasomes, the multiprotein complexes necessary for caspase-1 activation and the maturation of inflammatory cytokines such as IL-1? or IL-18. Here we demonstrate that both the NLRP3 and NLRC4 inflammasomes are activated by thermostable direct hemolysins (TDHs) and type III secretion system 1 (T3SS1) in response to V. parahaemolyticus infection. Furthermore, we identify T3SS1 secreted effector proteins, VopQ and VopS, which induce autophagy and the inactivation of Cdc42, respectively, to prevent mainly NLRC4 inflammasome activation. VopQ and VopS interfere with the assembly of specks in infected macrophages. These data suggest that bacterial effectors interfere with inflammasome activation and contribute to bacterial evasion from the host inflammatory responses.

Higa, Naomi; Toma, Claudia; Koizumi, Yukiko; Nakasone, Noboru; Nohara, Toshitsugu; Masumoto, Junya; Kodama, Toshio; Iida, Tetsuya; Suzuki, Toshihiko

2013-01-01

20

The 1,4-benzodiazepine Ro5-4864 (4-chlorodiazepam) suppresses multiple pro-inflammatory mast cell effector functions.  

PubMed

Activation of mast cells (MCs) can be achieved by the high-affinity receptor for IgE (Fc?RI) as well as by additional receptors such as the lipopolysaccharide (LPS) receptor and the receptor tyrosine kinase Kit (stem cell factor [SCF] receptor). Thus, pharmacological interventions which stabilize MCs in response to different receptors would be preferable in diseases with pathological systemic MC activation such as systemic mastocytosis. 1,4-Benzodiazepines (BDZs) have been reported to suppress MC effector functions. In the present study, our aim was to analyze molecularly the effects of BDZs on MC activation by comparison of the effects of the two BDZs Ro5-4864 and clonazepam, which markedly differ in their affinities for the archetypical BDZ recognition sites, i.e., the GABAA receptor and TSPO (previously termed peripheral-type BDZ receptor). Ro5-4864 is a selective agonist at TSPO, whereas clonazepam is a selective agonist at the GABAA receptor. Ro5-4864 suppressed pro-inflammatory MC effector functions in response to antigen (Ag) (degranulation/cytokine production) and LPS and SCF (cytokine production), whereas clonazepam was inactive. Signaling pathway analyses revealed inhibitory effects of Ro5-4864 on Ag-triggered production of reactive oxygen species, calcium mobilization and activation of different downstream kinases. The initial activation of Src family kinases was attenuated by Ro5-4864 offering a molecular explanation for the observed impacts on various downstream signaling elements. In conclusion, BDZs structurally related to Ro5-4864 might serve as multifunctional MC stabilizers without the sedative effect of GABAA receptor-interacting BDZs. PMID:23425659

Yousefi, Omid Sascha; Wilhelm, Thomas; Maschke-Neuß, Karin; Kuhny, Marcel; Martin, Christian; Molderings, Gerhard J; Kratz, Felix; Hildenbrand, Bernd; Huber, Michael

2013-02-20

21

A Pseudomonas syringae type III effector suppresses cell wall-based extracellular defense in susceptible Arabidopsis plants  

Microsoft Academic Search

Bacterial effector proteins secreted through the type III secretion system (TTSS) play a crucial role in causing plant and human diseases. Although the ability of type III effectors to trigger defense responses in resistant plants is well understood, the disease-promoting functions of type III effectors in susceptible plants are largely enigmatic. Previous microscopic studies suggest that in susceptible plants the

Paula Hauck; Roger Thilmony; Sheng Yang He

2003-01-01

22

Attaching and Effacing Bacterial Effector NleC Suppresses Epithelial Inflammatory Responses by Inhibiting NF-?B and p38 Mitogen-Activated Protein Kinase Activation ?  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli are noninvasive attaching and effacing (A/E) bacterial pathogens that cause intestinal inflammation and severe diarrheal disease. These pathogens utilize a type III secretion system to deliver effector proteins into host epithelial cells, modulating diverse cellular functions, including the release of the chemokine interleukin-8 (IL-8). While studies have implicated the effectors NleE (non-locus of enterocyte effacement [LEE]-encoded effector E) and NleH1 in suppressing IL-8 release, by preventing NF-?B nuclear translocation, the impact of these effectors only partially replicates the immunosuppressive actions of wild-type EPEC, suggesting another effector or effectors are involved. Testing an array of EPEC mutants, we identified the non-LEE-encoded effector C (NleC) as also suppressing IL-8 release. Infection by ?nleC EPEC led to exaggerated IL-8 release from infected Caco-2 and HT-29 epithelial cells. NleC localized to EPEC-induced pedestals, with signaling studies revealing NleC inhibits both NF-?B and p38 mitogen-activated protein kinase (MAPK) activation. Using Citrobacter rodentium, a mouse-adapted A/E bacterium, we found that ?nleC and wild-type C. rodentium-infected mice carried similar pathogen burdens, yet ?nleC strain infection led to worsened colitis. Similarly, infection with ?nleC C. rodentium in a cecal loop model induced significantly greater chemokine responses than infection with wild-type bacteria. These studies thus advance our understanding of how A/E pathogens subvert host inflammatory responses.

Sham, Ho Pan; Shames, Stephanie R.; Croxen, Matthew A.; Ma, Caixia; Chan, Justin M.; Khan, Mohammed A.; Wickham, Mark E.; Deng, Wanyin; Finlay, B. Brett; Vallance, Bruce A.

2011-01-01

23

SOBER1 phospholipase activity suppresses phosphatidic acid accumulation and plant immunity in response to bacterial effector AvrBsT.  

PubMed

Arabidopsis thaliana ecotype Pi-0 is resistant to Pseudomonas syringae pathovar tomato (Pst) strain DC3000 expressing the T3S effector protein AvrBsT. Resistance is due to a loss of function mutation (sober1-1) in a conserved alpha/beta hydrolase, SOBER1 (Suppressor of AvrBsT Elicited Resistance1). Members of this superfamily possess phospholipase and carboxylesterase activity with diverse substrate specificity. The nature of SOBER1 enzymatic activity and substrate specificity was not known. SOBER1-dependent suppression of the hypersensitive response (HR) in Pi-0 suggested that it might hydrolyze a plant lipid or precursor required for HR induction. Here, we show that Pi-0 leaves infected with Pst DC3000 expressing AvrBsT accumulated higher levels of phosphatidic acid (PA) compared to leaves infected with Pst DC3000. Phospholipase D (PLD) activity was required for high PA levels and AvrBsT-dependent HR in Pi-0. Overexpression of SOBER1 in Pi-0 reduced PA levels and inhibited HR. These data implicated PA, phosphatidylcholine (PC) and lysophosphatidylcholine (LysoPC) as potential SOBER1 substrates. Recombinant His(6)-SOBER1 hydrolyzed PC but not PA or LysoPC in vitro indicating that the enzyme has phospholipase A(2) (PLA(2)) activity. Chemical inhibition of PLA(2) activity in leaves expressing SOBER1 resulted in HR in response to Pst DC3000 AvrBsT. These data are consistent with the model that SOBER1 PLA(2) activity suppresses PLD-dependent production of PA in response to AvrBsT elicitation. This work highlights an important role for SOBER1 in the regulation of PA levels generated in plants in response to biotic stress. PMID:19918071

Kirik, Angela; Mudgett, Mary Beth

2009-11-16

24

Regulatory T cell expression of herpesvirus entry mediator suppresses the function of B and T lymphocyte attenuator-positive effector T cells.  

PubMed

The binding of herpesvirus entry mediator (HVEM) to B and T lymphocyte attenuator (BTLA) is known to activate an inhibitory signaling cascade in effector T (Teff) cells, but we now report that the HVEM-BTLA pathway is also important to the suppressive function of regulatory T cells (Tregs). Although naive T cells up-regulated BTLA upon TCR activation, Treg expression of BTLA remained low, regardless of TCR activation. Moreover, BTLA(-/-) CD4(+)CD25(+) Tregs had normal suppressive activity, whereas BTLA(-/-) Teff cells were more resistant than wild-type Teff cells to suppression by Tregs, suggesting BTLA expression by Teff cells was required for their suppression by Tregs. In contrast to BTLA, HVEM expression was comparable in naive Tregs vs Teff cells, but after stimulation HVEM expression was quickly down-regulated by Teff cells, whereas HVEM was further up-regulated by Tregs. HVEM(-/-) Tregs had decreased suppressive activity as compared with wild-type Tregs, indicating that Treg expression of HVEM was required for optimal suppression. Consistent with this, T cells from Scurfy mice (FoxP3 mutant) lacked HVEM gene expression, and adoptively transferred wild-type but not HVEM(-/-) Tregs were able to control alloresponses in vivo by normal Teff cells. Our data demonstrate that Tregs can exert their effects via up-regulation of the negative costimulatory ligand HVEM, which upon binding to BTLA expressed by Teff cells helps mediate the suppressive functions of Tregs in vitro and in vivo. PMID:18453584

Tao, Ran; Wang, Liqing; Murphy, Kenneth M; Fraser, Christopher C; Hancock, Wayne W

2008-05-15

25

Imaging of Effector Memory T Cells during a Delayed-Type Hypersensitivity Reaction and Suppression by Kv1.3 Channel Block  

PubMed Central

SUMMARY Effector memory T (Tem) cells are essential mediators of autoimmune disease and delayed-type hypersensitivity (DTH), a convenient model for two-photon imaging of Tem cell participation in an inflammatory response. Shortly (3 hr) after entry into antigen-primed ear tissue, Tem cells stably attached to antigen-bearing antigen-presenting cells (APCs). After 24 hr, enlarged Tem cells were highly motile along collagen fibers and continued to migrate rapidly for 18 hr. Tem cells rely on voltage-gated Kv1.3 potassium channels to regulate calcium signaling. ShK-186, a specific Kv1.3 blocker, inhibited DTH and suppressed Tem cell enlargement and motility in inflamed tissue but had no effect on homing to or motility in lymph nodes of naive and central memory T (Tcm) cells. ShK-186 effectively treated disease in a rat model of multiple sclerosis. These results demonstrate a requirement for Kv1.3 channels in Tem cells during an inflammatory immune response in peripheral tissues. Targeting Kv1.3 allows for effector memory responses to be suppressed while central memory responses remain intact.

Matheu, Melanie P.; Beeton, Christine; Garcia, Adriana; Chi, Victor; Rangaraju, Srikant; Safrina, Olga; Monaghan, Kevin; Uemura, Marc I.; Li, Dan; Pal, Sukumar; de la Maza, Luis M.; Monuki, Edwin; Flugel, Alexander; Pennington, Michael W.; Parker, Ian; Chandy, K. George; Cahalan, Michael D.

2009-01-01

26

Regulation of the t-cell response to ectromelia virus infection. I. Feedback suppression by effector t cells  

Microsoft Academic Search

Recovery of mice from primary infection with ectromelia virus, a natural mouse pathogen, has been shown to depend on cell-mediated immunity (CMI) 1 (1-3). The specific effector cells are known to be thymus-derived lymphocytes (T cells) (2-6). CMI can be measured in two ways. First, by transferring immune T cells into preinfected recipients and quantitating virus clearance in vivo (2,

T. Pang; R. V. BLANDEN

1976-01-01

27

CMPG1-dependent cell death follows perception of diverse pathogen elicitors at the host plasma membrane and is suppressed by Phytophthora infestans RXLR effector AVR3a.  

PubMed

• Little is known about how effectors from filamentous eukaryotic plant pathogens manipulate host defences. Recently, Phytophthora infestans RXLR effector AVR3a has been shown to target and stabilize host E3 ligase CMPG1, which is required for programmed cell death (PCD) triggered by INF1. We investigated the involvement of CMPG1 in PCD elicited by perception of diverse pathogen proteins, and assessed whether AVR3a could suppress each. • The role of CMPG1 in PCD events was investigated using virus-induced gene silencing, and the ability of AVR3a to suppress each was determined by transient expression of natural forms (AVR3a(KI) and AVR3a(EM)) and a mutated form, AVR3a(KI/Y147del) , which is unable to interact with or stabilize CMPG1. • PCD triggered at the host plasma membrane by Cf-9/Avr9, Cf-4/Avr4, Pto/AvrPto or the oomycete pathogen-associated molecular pattern (PAMP), cellulose-binding elicitor lectin (CBEL), required CMPG1 and was suppressed by AVR3a, but not by the AVR3a(KI/Y147del) mutant. Conversely, PCD triggered by nucleotide-binding site-leucine-rich repeat (NBS-LRR) proteins R3a, R2 and Rx was independent of CMPG1 and unaffected by AVR3a. • CMPG1-dependent PCD follows perception of diverse pathogen elicitors externally or in association with the inner surface of the host plasma membrane. We argue that AVR3a targets CMPG1 to block initial signal transduction/regulatory processes following pathogen perception at the plasma membrane. PMID:21348873

Gilroy, Eleanor M; Taylor, Rosalind M; Hein, Ingo; Boevink, Petra; Sadanandom, Ari; Birch, Paul R J

2011-02-23

28

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

2012-11-30

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.

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

Microbial infection-induced expansion of effector T cells overcomes the suppressive effects of regulatory T cells via an IL-2 deprivation mechanism  

PubMed Central

Regulatory Foxp3+ T cells are a critical cell population that suppresses T cell activation in response to microbial and viral pathogens. We identify a cell-intrinsic mechanism by which effector CD4+ T cells overcome the suppressive effects of Treg cells in the context of three distinct infections, Toxoplasma gondii, Listeria monocytogenes, and vaccinia virus. The acute responses to the parasitic, bacterial, and viral pathogens resulted in a transient reduction in frequency and absolute number of Treg cells. The infection-induced partial loss of Treg cells was essential for the initiation of potent Th1 responses and for host protection against the pathogens. The observed disappearance of Treg cells was a result of insufficiency in IL-2 caused by the expansion of pathogen-specific CD4+ T cells with a limited capacity of IL-2 production. Exogenous IL-2 treatment during the parasitic, bacterial, and viral infections completely prevented the loss of Treg cells, but restoration of Treg cells resulted in a greatly enhanced susceptibility to the pathogens. These results demonstrate that the transient reduction in Treg cells induced by pathogens via IL-2 deprivation is essential for optimal T cell responses and for host resistance to microbial and viral pathogens.

Benson, Alicia; Murray, Sean; Divakar, Prashanthi; Burnaevskiy, Nikolay; Pifer, Reed; Forman, James; Yarovinsky, Felix

2011-01-01

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 Central

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.

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

2012-01-01

32

Silymarin inhibits ultraviolet radiation-induced immune suppression through DNA repair-dependent activation of dendritic cells and stimulation of effector T cells.  

PubMed

Silymarin inhibits UVB-induced immunosuppression in mouse skin. To identify the molecular mechanisms underlying this effect, we used an adoptive transfer approach in which dendritic cells (DCs) from the draining lymph nodes of donor mice that had been UVB-exposed and sensitized to 2,4,-dinitrofluorobenzene (DNFB) were transferred into naïve recipient mice. The contact hypersensitivity (CHS) response of the recipient mice to DNFB was then measured. When DCs were obtained from UVB-exposed donor mice that were not treated with silymarin, the CHS response was suppressed confirming the role of DCs in the UVB-induced immunosuppression. Silymarin treatment of UVB-exposed donor mice relieved this suppression of the CHS response in the recipients. Silymarin treatment was associated with rapid repair of UVB-induced cyclobutane pyrimidine dimers (CPDs) in DCs and silymarin treatment did not prevent UV-induced immunosuppression in XPA-deficient mice which are unable to repair UV-induced DNA damage. The CHS response in mice receiving DCs from silymarin-treated UV-exposed donor mice also was associated with enhanced secretion of Th1-type cytokines and stimulation of T cells. Adoptive transfer of T cells revealed that transfer of either CD8(+) or CD4(+) cells from silymarin-treated, UVB-exposed donors resulted in enhancement of the CHS response. Cell culture study showed enhanced secretion of IL-2 and IFN? by CD8(+) T cells, and reduced secretion of Th2 cytokines by CD4(+) T cells, obtained from silymarin-treated UVB-exposed mice. These data suggest that DNA repair-dependent functional activation of DCs, a reduction in CD4(+) regulatory T-cell activity, and stimulation of CD8(+) effector T cells contribute to silymarin-mediated inhibition of UVB-induced immunosuppression. PMID:23395695

Vaid, Mudit; Prasad, Ram; Singh, Tripti; Elmets, Craig A; Xu, Hui; Katiyar, Santosh K

2013-02-05

33

Effector-Mediated Suppression of Chitin-Triggered Immunity by Magnaporthe oryzae Is Necessary for Rice Blast Disease[C][W  

PubMed Central

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.

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

34

The Xanthomonas campestris Type III Effector XopJ Targets the Host Cell Proteasome to Suppress Salicylic-Acid Mediated Plant Defence  

PubMed Central

The phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) requires type III effector proteins (T3Es) for virulence. After translocation into the host cell, T3Es are thought to interact with components of host immunity to suppress defence responses. XopJ is a T3E protein from Xcv that interferes with plant immune responses; however, its host cellular target is unknown. Here we show that XopJ interacts with the proteasomal subunit RPT6 in yeast and in planta to inhibit proteasome activity. A C235A mutation within the catalytic triad of XopJ as well as a G2A exchange within the N-terminal myristoylation motif abolishes the ability of XopJ to inhibit the proteasome. Xcv ?xopJ mutants are impaired in growth and display accelerated symptom development including tissue necrosis on susceptible pepper leaves. Application of the proteasome inhibitor MG132 restored the ability of the Xcv ?xopJ to attenuate the development of leaf necrosis. The XopJ dependent delay of tissue degeneration correlates with reduced levels of salicylic acid (SA) and changes in defence- and senescence-associated gene expression. Necrosis upon infection with Xcv ?xopJ was greatly reduced in pepper plants with reduced expression of NPR1, a central regulator of SA responses, demonstrating the involvement of SA-signalling in the development of XopJ dependent phenotypes. Our results suggest that XopJ-mediated inhibition of the proteasome interferes with SA-dependent defence response to attenuate onset of necrosis and to alter host transcription. A central role of the proteasome in plant defence is discussed.

Bornke, Frederik

2013-01-01

35

Myeloid Dendritic Cells (DCs) of Mice Susceptible to Paracoccidioidomycosis Suppress T Cell Responses whereas Myeloid and Plasmacytoid DCs from Resistant Mice Induce Effector and Regulatory T Cells  

PubMed Central

The protective adaptive immune response in paracoccidioidomycosis, a mycosis endemic among humans, is mediated by T cell immunity, whereas impaired T cell responses are associated with severe, progressive disease. The early host response to Paracoccidioides brasiliensis infection is not known since the disease is diagnosed at later phases of infection. Our laboratory established a murine model of infection where susceptible mice reproduce the severe disease, while resistant mice develop a mild infection. This work aimed to characterize the influence of dendritic cells in the innate and adaptive immunity of susceptible and resistant mice. We verified that P. brasiliensis infection induced in bone marrow-derived dendritic cells (DCs) of susceptible mice a prevalent proinflammatory myeloid phenotype that secreted high levels of interleukin-12 (IL-12), tumor necrosis factor alpha, and IL-?, whereas in resistant mice, a mixed population of myeloid and plasmacytoid DCs secreting proinflammatory cytokines and expressing elevated levels of secreted and membrane-bound transforming growth factor ? was observed. In proliferation assays, the proinflammatory DCs from B10.A mice induced anergy of naïve T cells, whereas the mixed DC subsets from resistant mice induced the concomitant proliferation of effector and regulatory T cells (Tregs). Equivalent results were observed during pulmonary infection. The susceptible mice displayed preferential expansion of proinflammatory myeloid DCs, resulting in impaired proliferation of effector T cells. Conversely, the resistant mice developed myeloid and plasmacytoid DCs that efficiently expanded gamma interferon-, IL-4-, and IL-17-positive effector T cells associated with increased development of Tregs. Our work highlights the deleterious effect of excessive innate proinflammatory reactions and provides new evidence for the importance of immunomodulation during pulmonary paracoccidioidomycosis.

Pina, Adriana; Frank de Araujo, Eliseu; Felonato, Maira; Loures, Flavio V.; Feriotti, Claudia; Bernardino, Simone; Barbuto, Jose Alexandre M.

2013-01-01

36

Suppression of Staphylococcus aureus Cowan I-induced immunoglobulin synthesis in vitro: discrimination between the presence of suppressor T cell precursors and effectors.  

PubMed Central

In co-cultures with control cells lymphocytes obtained from some patients with hypogammaglobulinaemia can suppress PWM but not S. aureus Cowan I-induced polyclonal immunoglobulin production. When such co-cultures were stimulated at the same time with both mitogens, the response was greatly suppressed. This phenomenon was further studied in cultures of lymphocyte populations isolated from healthy donors. It was found that suppressor T lymphocytes activated by PWM in cultures co-stimulated with Con A, with high T:B cell ratio, or with an increased proportion of OKT8+ T cells can suppress the S. aureus-induced response. In contrast, under the same conditions S. aureus did not activate suppressor cells. Moreover, in cultures stimulated with this polyclonal B-cell activator OKT8+ lymphocytes could serve as helper cells.

Pryjma, J; Pituch-Noworolska, A; Flad, H D; Ulmer, A J; Ernst, M

1986-01-01

37

Functional Foxp3+ CD4+ CD25(Bright+) "Natural" Regulatory T Cells Are Abundant in Rabbit Conjunctiva and Suppress Virus-Specific CD4+ and CD8+ Effector T Cells during Ocular Herpes Infection?  

PubMed Central

We studied the phenotype and distribution of “naturally” occurring CD4+ CD25+ T regulatory cells (CD4+ CD25+ nTreg cells) resident in rabbit conjunctiva, the main T-cell inductive site of the ocular mucosal immune system, and we investigated their suppressive capacities using herpes simplex virus type 1 (HSV-1)-specific effector T (Teff) cells induced during ocular infection. The expression of CD4, CD25, CTLA4, GITR, and Foxp3 was examined by reverse transcription-PCR, Western blotting, and fluorescence-activated cell sorter analysis in CD45+ pan-leukocytes isolated from conjunctiva, spleen, and peripheral blood monocyte cells (PBMC) of HSV-1-infected and uninfected rabbits. Normal conjunctiva showed a higher frequency of CD4+ CD25(Bright+) T cells than did spleen and PBMC. These cells expressed high levels of Foxp3, GITR, and CTLA4 molecules. CD4+ CD25(Bright+) T cells were localized continuously along the upper and lower palpebral and bulbar conjunctiva, throughout the epithelium and substantia propria. Conjunctiva-derived CD4+ CD25(Bright+) T cells, but not CD4+ CD25(low) T cells, efficiently suppressed HSV-specific CD4+ and CD8+ Teff cells. The CD4+ CD25(Bright+) T-cell-mediated suppression was effective on both peripheral blood and conjunctiva infiltrating Teff cells and was cell-cell contact dependent but independent of interleukin-10 and transforming growth factor ?. Interestingly, during an ocular herpes infection, there was a selective increase in the frequency and suppressive capacity of Foxp3+ CD4+ CD25(Bright+) T cells in conjunctiva but not in the spleen or in peripheral blood. Altogether, these results provide the first evidence that functional Foxp3+ CD4+ CD25(Bright+) Treg cells accumulate in the conjunctiva. It remains to be determined whether conjunctiva CD4+ CD25+ nTreg cells affect the topical/mucosal delivery of subunit vaccines that stimulate the ocular mucosal immune system.

Nesburn, Anthony B.; Bettahi, Ilham; Dasgupta, Gargi; Chentoufi, Alami Aziz; Zhang, Xiuli; You, Sylvaine; Morishige, Naoyuki; Wahlert, Andrew J.; Brown, Donald J.; Jester, James V.; Wechsler, Steven L.; BenMohamed, Lbachir

2007-01-01

38

Pseudomonas syringae type III effector HopZ1 targets a host enzyme to suppress isoflavone biosynthesis and promote infection in soybean.  

PubMed

Type III secreted effectors (T3SEs), such as Pseudomonas syringae HopZ1, are essential bacterial virulence proteins injected into the host cytosol to facilitate infection. However, few direct targets of T3SEs are known. Investigating the target(s) of HopZ1 in soybean, a natural P. syringae host, we find that HopZ1 physically interacts with the isoflavone biosynthesis enzyme, 2-hydroxyisoflavanone dehydratase (GmHID1). P. syringae infection induces gmhid1 expression and production of daidzein, a major soybean isoflavone. Silencing gmhid1 increases susceptibility to P. syringae infection, supporting a role for GmHID1 in innate immunity. P. syringae expressing active but not the catalytic mutant of HopZ1 inhibits daidzein induction and promotes bacterial multiplication in soybean. HopZ1-enhanced P. syringae multiplication is at least partially dependent on GmHID1. Thus, GmHID1 is a virulence target of HopZ1 to promote P. syringae infection of soybean. This work highlights the isoflavonoid biosynthesis pathway as an antibacterial defense mechanism and a direct T3SE target. PMID:21402357

Zhou, Huanbin; Lin, Jian; Johnson, Aimee; Morgan, Robyn L; Zhong, Wenwan; Ma, Wenbo

2011-03-17

39

Injury-induced suppression of effector T cell immunity requires CD1d-positive APCs and CD1d-restricted NKT cells.  

PubMed

Overwhelming infection remains the leading cause of death from serious burn injury despite recent advances in the care of burn patients and a better understanding of immune and inflammatory consequences of injury. In this study, we report a critical requirement for CD1d-restricted NKT cells and CD1d expression by APCs in the immune dysfunction that occurs early after burn injury. Using a well-established murine scald injury model with BALB/c and BALB/c CD1d knockout mice, we investigated whether peripheral T cell immunity was affected by the presence or absence of CD1d-restricted NKT cells in the early stages after injury. Using Ag-specific delayed-type hypersensitivity, T cell proliferation, and cytokine production as indices of immune responsiveness, we observed that both CD1d expression by APCs and CD1d-restricted NKT cells are required for immune suppression after injury. Via adoptive transfer of splenocytes from injured mice to uninjured recipients, we found injury-induced suppression of immunity to be Ag specific, long lasting, and critically dependent on cell surface expression of CD1d by APCs. Together, our results suggest that the defects in T cell responsiveness that occur subsequent to severe burn injury are not merely the result of global or passive suppression, but instead represent an active form of CD1d/NKT cell-dependent immunologic tolerance. PMID:16785503

Palmer, Jessica L; Tulley, Julia M; Kovacs, Elizabeth J; Gamelli, Richard L; Taniguchi, Masaru; Faunce, Douglas E

2006-07-01

40

XopR, a type III effector secreted by Xanthomonas oryzae pv. oryzae, suppresses microbe-associated molecular pattern-triggered immunity in Arabidopsis thaliana.  

PubMed

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial blight of rice. The XopR protein, secreted into plant cells through the type III secretion apparatus, is widely conserved in xanthomonads and is predicted to play important roles in bacterial pathogenicity. Here, we examined the function of XopR by constructing transgenic Arabidopsis thaliana plants expressing it under control of the dexamethasone (DEX)-inducible promoter. In the transgenic plants treated with DEX, slightly delayed growth and variegation on leaves were observed. Induction of four microbe-associated molecular pattern (MAMP)-specific early-defense genes by a nonpathogenic X. campestris pv. campestris hrcC deletion mutant were strongly suppressed in the XopR-expressing plants. XopR expression also reduced the deposition of callose, an immune response induced by flg22. When transiently expressed in Nicotiana benthamiana, a XopR::Citrine fusion gene product localized to the plasma membrane. The deletion of XopR in X. oryzae pv. oryzae resulted in reduced pathogenicity on host rice plants. Collectively, these results suggest that XopR inhibits basal defense responses in plants rapidly after MAMP recognition. PMID:22204644

Akimoto-Tomiyama, Chiharu; Furutani, Ayako; Tsuge, Seiji; Washington, Erica J; Nishizawa, Yoko; Minami, Eiichi; Ochiai, Hirokazu

2012-04-01

41

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

42

Effector functions of pathogenic Yersinia species.  

PubMed

Pathogenic species of the genus Yersinia suppress and reorient the immune system to infect lymphatic tissues, inner organs and at times also the vasculature. For this purpose yersiniae employ a type III secretion system to translocate effector proteins (Yersinia outer proteins; Yops) into immune cells. Yops often exert unique biochemical activities for modulating the activity of Rho GTP-binding proteins, focal adhesion proteins, inflammatory pathways and cell survival/apoptosis. In this review we will put emphasis on the biochemistry, cell- and infection biology of Yersinia effector Yops. PMID:17849040

Aepfelbacher, Martin; Trasak, Claudia; Ruckdeschel, Klaus

2007-09-01

43

Effector Caspases and Leukemia  

PubMed Central

Caspases, a family of aspartate-specific cysteine proteases, play a major role in apoptosis and a variety of physiological and pathological processes. Fourteen mammalian caspases have been identified and can be divided into two groups: inflammatory caspases and apoptotic caspases. Based on the structure and function, the apoptotic caspases are further grouped into initiator/apical caspases (caspase-2, -8, -9, and -10) and effector/executioner caspases (caspase-3, -6, and -7). In this paper, we discuss what we have learned about the role of individual effector caspase in mediating both apoptotic and nonapoptotic events, with special emphasis on leukemia-specific oncoproteins in relation to effector caspases.

Lu, Ying; Chen, Guo-Qiang

2011-01-01

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

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

46

Visual sensor based vibration control and end-effector control for flexible robot arms  

Microsoft Academic Search

This paper addresses the issue of measurement and control of robot arms with link flexibility. A measurement system for link flexural deflection and end-effector position sensing using CCD camera and video tracker is presented. Based on the measurement system, both link vibration suppressing control scheme and end-effector trajectory tracking control scheme are designed. Experiments for link vibration control and end-effector

Zhao-Hui Jiang; A. Goto

2005-01-01

47

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.

Belyi, Yury; Jank, Thomas; Aktories, Klaus

2011-01-01

48

Trio's Rho-specific GEF domain is the missing G q effector in C. elegans  

Microsoft Academic Search

The Gq pathway is essential for animal life and is a central pathway for driving locomotion, egg laying, and growth in Caenorhabditis elegans, where it exerts its effects through EGL-8 (phospholipase C (PLC)) and at least one other effector. To find the missing effector, we performed forward genetic screens to suppress the slow growth and hyperactive behaviors of mutants with

Stacey L. Williams; Susanne Lutz; Nicole K. Charlie; Christiane Vettel; Michael Ailion; Cassandra Coco; John J. G. Tesmer; Erik M. Jorgensen; Thomas Wieland; Kenneth G. Miller

2007-01-01

49

Inactivation of Effector Caspases through Nondegradative Polyubiquitylation  

PubMed Central

SUMMARY Ubiquitin-mediated inactivation of caspases has long been postulated to contribute to the regulation of apoptosis. However, detailed mechanisms and functional consequences of caspase ubiquitylation have not been demonstrated. Here we show that the Drosophila Inhibitor of Apoptosis 1, DIAP1, blocks effector caspases by targeting them for polyubiquitylation and nonproteasomal inactivation. We demonstrate that the conjugation of ubiquitin to drICE suppresses its catalytic potential in cleaving caspase substrates. Our data suggest that ubiquitin conjugation sterically interferes with substrate entry and reduces the caspase’s proteolytic velocity. Disruption of drICE ubiquitylation, either by mutation of DIAP1’s E3 activity or drICE’s ubiquitin-acceptor lysines, abrogates DIAP1’s ability to neutralize drICE and suppress apoptosis in vivo. We also show that DIAP1 rests in an “inactive” conformation that requires caspase-mediated cleavage to subsequently ubiquitylate caspases. Taken together, our findings demonstrate that effector caspases regulate their own inhibition through a negative feedback mechanism involving DIAP1 “activation” and nondegradative polyubiquitylation.

Ditzel, Mark; Broemer, Meike; Tenev, Tencho; Bolduc, Clare; Lee, Tom V.; Rigbolt, Kristoffer T.G.; Elliott, Richard; Zvelebil, Marketa; Blagoev, Blagoy; Bergmann, Andreas; Meier, Pascal

2009-01-01

50

The Alpha-Melanocyte Stimulating Hormone Induces Conversion of Effector T Cells into Treg Cells  

PubMed Central

The neuropeptide alpha-melanocyte stimulating hormone (?-MSH) has an important role in modulating immunity and homeostasis. The production of IFN-? by effector T cells is suppressed by ?-MSH, while TGF-? production is promoted in the same cells. Such ?-MSH-treated T cells have immune regulatory activity and suppress hypersensitivity, autoimmune diseases, and graft rejection. Previous characterizations of the ?-MSH-induced Treg cells showed that the cells are CD4+ T cells expressing the same levels of CD25 as effector T cells. Therefore, we further analyzed the ?-MSH-induced Treg cells for expression of effector and regulatory T-cell markers. Also, we examined the potential for ?-MSH-induced Treg cells to be from the effector T-cell population. We found that the ?-MSH-induced Treg cells are CD25+??CD4+ T cells that share similar surface markers as effector T cells, except that they express on their surface LAP. Also, the ?-MSH treatment augments FoxP3 message in the effector T cells, and ?-MSH induction of regulatory activity was limited to the effector CD25+ T-cell population. Therefore, ?-MSH converts effector T cells into Treg cells, which suppress immunity targeting specific antigens and tissues.

Taylor, Andrew W.; Lee, Darren J.

2011-01-01

51

Phytopathogen type III effector weaponry and their plant targets  

PubMed Central

Summary Phytopathogenic bacteria suppress plant innate immunity and promote pathogenesis by injecting proteins called type III effectors into plant cells using a type III protein secretion system. These type III effectors use at least three major strategies to alter host responses. One strategy is to alter host protein turnover, either by direct cleavage or by modulating ubiquitination and targeting to the 26S proteasome. Another strategy involves alteration of RNA metabolism by transcriptional activation or ADP-ribosylation of RNA-binding proteins. A third major strategy is to inhibit the kinases involved in plant defence signalling, either by removing phosphates or by direct inhibition. The wide array of strategies bacterial pathogens employ to suppress innate immunity suggest that circumvention of innate immunity is critical for bacterial pathogenicity of plants.

Block, Anna; Li, Guangyong; Fu, Zheng Qing; Alfano, James R.

2008-01-01

52

Identification of legionella effectors using bioinformatic approaches.  

PubMed

Legionella pneumophila the causative agent of Legionnaires' disease, actively manipulates host cell processes to establish a replication niche inside host cells. The establishment of its replication niche requires a functional Icm/Dot type IV secretion system which translocates about 300 effector proteins into host cells during infection. Many of these effectors were first identified as effector candidates by several bioinformatic approaches, and these predicted effectors were later examined experimentally for translocation and a large number of which were validated as effector proteins. Here, I summarized the bioinformatic approaches that were used to identify these effectors. PMID:23150423

Segal, Gil

2013-01-01

53

Diversity of effector genes in plant pathogenic bacteria of genus Xanthomonas  

Microsoft Academic Search

Gram-negative plant pathogenic bacteria are secreting into plant cell a special type of pathogeni city-related proteins called\\u000a effectors. They are capable of suppressing plant innate immunity or stimulating synthesis and export of metabolites desired\\u000a by the pathogen. We identified a number of effector-coding genes typical of xanthomonads analyzing 8 completely sequenced\\u000a genomes of genus Xanthomonas. Using representative collection provided by

M. V. Mokryakova; I. A. Abdeeva; E. S. Piruzyan; N. W. Schaad; A. N. Ignatov

2010-01-01

54

Improving a Gripper End Effector  

SciTech Connect

This paper discusses the improvement made to an existing four-bar linkage gripping end effector to adapt it for use in a current project. The actuating linkage was modified to yield higher jaw force overall and particularly in the critical range of jaw displacement

Mullen, O Dennis; Smith, Christopher M.; Gervais, Kevin L.

2001-01-31

55

RNAi Effector Diversity in Nematodes  

Microsoft Academic Search

While RNA interference (RNAi) has been deployed to facilitate gene function studies in diverse helminths, parasitic nematodes appear variably susceptible. To test if this is due to inter-species differences in RNAi effector complements, we performed a primary sequence similarity survey for orthologs of 77 Caenorhabditis elegans RNAi pathway proteins in 13 nematode species for which genomic or transcriptomic datasets were

Johnathan J. Dalzell; Paul McVeigh; Neil D. Warnock; Makedonka Mitreva; David Mc K. Bird; Pierre Abad; Colin C. Fleming; Tim A. Day; Angela Mousley; Nikki J. Marks; Aaron G. Maule

2011-01-01

56

Dexterous end effector flight demonstration  

NASA Astrophysics Data System (ADS)

The Dexterous End Effector Flight Experiment is a flight demonstration of newly developed equipment and methods which make for more dexterous manipulation of robotic arms. The following concepts are to be demonstrated: The Force Torque Sensor is a six axis load cell located at the end of the RMS which displays load data to the operator on the orbiter CCTV monitor. TRAC is a target system which provides six axis positional information to the operator. It has the characteristic of having high sensitivity to attitude misalignment while being flat. AUTO-TRAC is a variation of TRAC in which a computer analyzes a target, displays translational and attitude misalignment information, and provides cues to the operator for corrective inputs. The Magnetic End Effector is a fault tolerant end effector which grapples payloads using magnetic attraction. The Carrier Latch Assembly is a fault tolerant payload carrier, which uses mechanical latches and/or magnetic attraction to hold small payloads during launch/landing and to release payloads as desired. The flight experiment goals and objectives are explained. The experiment equipment is described, and the tasks to be performed during the demonstration are discussed.

Carter, Edward L.; Monford, Leo G.

1994-01-01

57

Using Hierarchical Clustering of Secreted Protein Families to Classify and Rank Candidate Effectors of Rust Fungi  

PubMed Central

Rust fungi are obligate biotrophic pathogens that cause considerable damage on crop plants. Puccinia graminis f. sp. tritici, the causal agent of wheat stem rust, and Melampsora larici-populina, the poplar leaf rust pathogen, have strong deleterious impacts on wheat and poplar wood production, respectively. Filamentous pathogens such as rust fungi secrete molecules called disease effectors that act as modulators of host cell physiology and can suppress or trigger host immunity. Current knowledge on effectors from other filamentous plant pathogens can be exploited for the characterisation of effectors in the genome of recently sequenced rust fungi. We designed a comprehensive in silico analysis pipeline to identify the putative effector repertoire from the genome of two plant pathogenic rust fungi. The pipeline is based on the observation that known effector proteins from filamentous pathogens have at least one of the following properties: (i) contain a secretion signal, (ii) are encoded by in planta induced genes, (iii) have similarity to haustorial proteins, (iv) are small and cysteine rich, (v) contain a known effector motif or a nuclear localization signal, (vi) are encoded by genes with long intergenic regions, (vii) contain internal repeats, and (viii) do not contain PFAM domains, except those associated with pathogenicity. We used Markov clustering and hierarchical clustering to classify protein families of rust pathogens and rank them according to their likelihood of being effectors. Using this approach, we identified eight families of candidate effectors that we consider of high value for functional characterization. This study revealed a diverse set of candidate effectors, including families of haustorial expressed secreted proteins and small cysteine-rich proteins. This comprehensive classification of candidate effectors from these devastating rust pathogens is an initial step towards probing plant germplasm for novel resistance components.

Saunders, Diane G. O.; Win, Joe; Cano, Liliana M.; Szabo, Les J.; Kamoun, Sophien; Raffaele, Sylvain

2012-01-01

58

Mesenchymal stem cell effects on T-cell effector pathways  

PubMed Central

Mesenchymal stem (stromal) cells (MSCs) are rare, multipotent progenitor cells that can be isolated and expanded from bone marrow and other tissues. Strikingly, MSCs modulate the functions of immune cells, including T cells, B cells, natural killer cells, monocyte/macrophages, dendritic cells, and neutrophils. T cells, activated to perform a range of different effector functions, are the primary mediators of many autoimmune and inflammatory diseases as well as of transplant rejection and graft-versus-host disease. Well-defined T-cell effector phenotypes include the CD4+ (T helper cell) subsets Th1, Th2, and Th17 cells and cytotoxic T lymphocytes derived from antigen-specific activation of naïve CD8+ precursors. In addition, naturally occurring and induced regulatory T cells (Treg) represent CD4+ and CD8+ T-cell phenotypes that potently suppress effector T cells to prevent autoimmunity, maintain self-tolerance, and limit inflammatory tissue injury. Many immune-mediated diseases entail an imbalance between Treg and effector T cells of one or more phenotypes. MSCs broadly suppress T-cell activation and proliferation in vitro via a plethora of soluble and cell contact-dependent mediators. These mediators may act directly upon T cells or indirectly via modulation of antigen-presenting cells and other accessory cells. MSC administration has also been shown to be variably associated with beneficial effects in autoimmune and transplant models as well as in several human clinical trials. In a small number of studies, however, MSC administration has been found to aggravate T cell-mediated tissue injury. The multiple effects of MSCs on cellular immunity may reflect their diverse influences on the different T-cell effector subpopulations and their capacity to specifically protect or induce Treg populations. In this review, we focus on findings from the recent literature in which specific modulatory effects of MSCs on one or more individual effector T-cell subsets and Treg phenotypes have been examined in vitro, in relevant animal models of in vivo immunological disease, and in human subjects. We conclude that MSCs have the potential to directly or indirectly inhibit disease-associated Th1, Th2, and Th17 cells as well as cytotoxic T lymphocytes but that many key questions regarding the potency, specificity, mechanistic basis, and predictable therapeutic value of these modulatory effects remain unanswered.

2011-01-01

59

Identification of Hyaloperonospora arabidopsidis Transcript Sequences Expressed during Infection Reveals Isolate-Specific Effectors  

PubMed Central

Biotrophic plant pathogens secrete effector proteins that are important for infection of the host. The aim of this study was to identify effectors of the downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) that are expressed during infection of its natural host Arabidopsis thaliana. Infection-related transcripts were identified from Expressed Sequence Tags (ESTs) derived from leaves of the susceptible Arabidopsis Ws eds1-1 mutant inoculated with the highly virulent Hpa isolate Waco9. Assembly of 6364 ESTs yielded 3729 unigenes, of which 2164 were Hpa-derived. From the translated Hpa unigenes, 198 predicted secreted proteins were identified. Of these, 75 were found to be Hpa-specific and six isolate Waco9-specific. Among 42 putative effectors identified there were three Elicitin-like proteins, 16 Cysteine-rich proteins and 18 host-translocated RXLR effectors. Sequencing of alleles in different Hpa isolates revealed that five RXLR genes show signatures of diversifying selection. Thus, EST analysis of Hpa-infected Arabidopsis is proving to be a powerful method for identifying pathogen effector candidates expressed during infection. Delivery of the Waco9-specific protein RXLR29 in planta revealed that this effector can suppress PAMP-triggered immunity and enhance disease susceptibility. We propose that differences in host colonization can be conditioned by isolate-specific effectors.

Cabral, Adriana; Stassen, Joost H. M.; Seidl, Michael F.; Bautor, Jaqueline; Parker, Jane E.; Van den Ackerveken, Guido

2011-01-01

60

Computational investigation of miniature trailing edge effectors  

NASA Astrophysics Data System (ADS)

Miniature trailing edge effectors (MiTEs) are small flaps (typically 1% to 5% chord) actuated with deflection angles of up to 90 degrees. The small size, combined with little required power and good control authority, enables the device to be used for high bandwidth control as well as conventional attitude control. However, some of the aerodynamic characteristics of these devices are complex and poorly understood. This research investigated the aerodynamics of MiTEs using incompressible Navier-Stokes flow solvers, INS2D and INS3D. To understand the flow structure and establish a parametric database, two dimensional steady-state computations were performed for MiTEs with various geometries and flow conditions. Time accurate computations were used to resolve the unsteady characteristics including transient response and vortex shedding phenomena. The frequency response was studied to fully identify the dynamics of MiTEs. Three dimensional computations show the change in control effectiveness with respect to the spanwise length of MiTEs as well as the spanwise lift distribution induced by these devices. Based on the CFD results, an approximate vortex panel model was developed for design purposes that reproduces the key characteristics of MiTEs. Two application areas for MiTEs were explored. Flutter suppression was demonstrated by combining a finite element structural model with the vortex panel model. The application of MiTEs to augment maximum lift and improve the post stall behavior of an airfoil was also investigated.

Lee, Hak-Tae

61

TAL effector nuclease (TALEN) engineering.  

PubMed

TALENs, fusion proteins of DNA binding domains of TAL (transcription activator-like) effectors and the DNA cleavage domains of endonuclease FokI, have emerged as genetic tools for targeted gene modification, holding great potential for basic and applied research, even for gene therapy. Here we present a simple and efficient approach to custom-engineering TALEN genes with four basic TAL repeats and their DNA recognition cipher. The "modular assembly" method also involves the "Golden Gate" cloning strategy, using 53 ready-to-use plasmids in just two rounds of restriction and ligation to assemble TALENs with up to 24 repeat units that recognize up to 24 bp of target DNA. PMID:23423889

Li, Ting; Yang, Bing

2013-01-01

62

Distinct Functions of Autoreactive Memory and Effector CD4+ T Cells in Experimental Autoimmune Encephalomyelitis  

PubMed Central

The persistence of human autoimmune diseases is thought to be mediated predominantly by memory T cells. We investigated the phenotype and migration of memory versus effector T cells in vivo in experimental autoimmune encephalomyelitis (EAE). We found that memory CD4+ T cells up-regulated the activation marker CD44 as well as CXCR3 and ICOS, proliferated more and produced more interferon-? and less interleukin-17 compared to effector T cells. Moreover, adoptive transfer of memory T cells into T cell receptor (TCR)???/? recipients induced more severe disease than did effector CD4+ T cells with marked central nervous system inflammation and axonal damage. The uniqueness of disease mediated by memory T cells was confirmed by the differential susceptibility to immunomodulatory therapies in vivo. CD28-B7 T cell costimulatory signal blockade by CTLA4Ig suppressed effector cell-mediated EAE but had minimal effects on disease induced by memory cells. In contrast, ICOS-B7h blockade exacerbated effector T cell-induced EAE but protected from disease induced by memory T cells. However, blockade of the OX40 (CD134) costimulatory pathway ameliorated disease mediated by both memory and effector T cells. Our data extend the understanding of the pathogenicity of autoreactive memory T cells and have important implications for the development of novel therapies for human autoimmune diseases.

Elyaman, Wassim; Kivisakk, Pia; Reddy, Jay; Chitnis, Tanuja; Raddassi, Khadir; Imitola, Jaime; Bradshaw, Elizabeth; Kuchroo, Vijay K.; Yagita, Hideo; Sayegh, Mohamed H.; Khoury, Samia J.

2008-01-01

63

Structural aspects of Rab6-effector complexes.  

PubMed

The small GTPase Rab6 regulates vesicle trafficking at the level of Golgi. Recently, the crystal structures of Rab6 in complexes with two unrelated effectors have been determined. The structure of Rab6a-GTP in complex with a 378-residue internal fragment of the effector Rab6IP1 (Rab6-interacting protein 1) has been solved. In addition, the structure of Rab6 with the golgin, GCC185, has also been determined. In both complexes, two alpha-helices from the effector mediate binding to switch I, switch II and the interswitch region of Rab6. Comparisons of the complexes reveal significant conformational changes in the conserved hydrophobic triad of Rab6. Thus conformational flexibility in the triad mediates recognition of compositionally distinct alpha-helical coiled coils, providing a rationale for the promiscuity of Rab6 in effector recruitment. PMID:19754447

Fernandes, Humberto; Franklin, Edward; Recacha, Rosario; Houdusse, Anne; Goud, Bruno; Khan, Amir R

2009-10-01

64

Heterotrimeric G Proteins and Their Effector Pathways  

Microsoft Academic Search

Almost 30 yr have passed since the discovery of the heptahelical transmembrane (TM) receptors and their connection to heterotrimeric\\u000a G proteins and sequential signal flow to intracellular effectors (1–3). Many hormones, sensory stimuli, and neurotransmitters use this signaling system to convert chemical or physical information\\u000a from the G protein-coupled receptor (GPCR) through a transducer (G protein) to an effector into

Tracy Nguyen Hwangpo; Ravi Iyengar

65

Cutting Edge: Responder T Cells Regulate Human DR+ Effector Regulatory T Cell Activity via Granzyme1  

PubMed Central

MHC class II expression identifies an effector subset of human CD4+CD25highFoxP3high natural regulatory T cells (DR+ Tregs) that induces more rapid suppression and exhibits higher FoxP3 expression than the remaining Treg population. Although Tregs are known to be highly sensitive to apoptosis, in this study we demonstrate that this sensitivity is primarily a feature of DR+ Tregs. Granzyme B (GzmB) is strongly expressed by nonregulatory responder CD4 T cells, whereas effector DR+ Tregs express little GzmB. Strong TCR stimulation markedly increases the expression of GzmB in all dividing responder CD4 T cells and mitigates the suppression by DR+ Tregs. DR+ Treg suppressive activity reemerges if GzmB is neutralized. We show that responder cells actively kill effector Tregs by producing GzmB in response to strong TCR stimulation. Thus, the production of GzmB by strongly activated CD4 T cells represents a mechanism by which CD4 T cells resist Treg suppression.

Ashley, Charles W.; Baecher-Allan, Clare

2010-01-01

66

Inhibition of murine nephritogenic effector T cells by a clone-specific suppressor factor.  

PubMed Central

We have used a murine model of organ-specific autoimmunity to characterize therapeutic modalities capable of down-regulating the cellular limb of the autoimmune response. Murine interstitial nephritis is an autoimmune disease mediated by tubular antigen-specific CD8+ nephritogenic effector T cells which are delayed-type hypersensitivity (DTH) reactive and cytotoxic to renal epithelial cells. Previous studies have demonstrated that disease can be suppressed with experimentally induced populations of T cells (Ts1 and Ts2 cells) obtained after injection of tubular antigen-coupled splenocytes into syngeneic mice. As the target of Ts2 is the CD8+ effector T cell, we have evaluated its effects on nephritogenic effector T cell clones isolated from diseased animals. Our studies demonstrate that soluble proteins expressed by Ts2 cells (TsF2) specifically abrogate the DTH, cytotoxic, and nephritogenic potential of M52 cells, although T cell receptor and IL-2 receptor expression are unchanged in these unresponsive M52 clones. TsF2-induced inhibition is dependent on new mRNA and protein synthesis. In a cytotoxic clone, M52.26, exposure to TsF2 induces expression of TGF-beta 1 which is, in turn, required for inhibition of cytotoxicity and nephritogenicity. Our studies are consistent with TGF-beta 1 behaving, at least in some T cells, as a nonspecific final effector of clone-specific suppression. Images

Meyers, C M; Kelly, C J

1994-01-01

67

Translocation of surface-localized effectors in type III secretion.  

PubMed

Pathogenic Yersinia species suppress the host immune response by using a plasmid-encoded type III secretion system (T3SS) to translocate virulence proteins into the cytosol of the target cells. T3SS-dependent protein translocation is believed to occur in one step from the bacterial cytosol to the target-cell cytoplasm through a conduit created by the T3SS upon target cell contact. Here, we report that T3SS substrates on the surface of Yersinia pseudotuberculosis are translocated into target cells. Upon host cell contact, purified YopH coated on Y. pseudotuberculosis was specifically and rapidly translocated across the target-cell membrane, which led to a physiological response in the infected cell. In addition, translocation of externally added YopH required a functional T3SS and a specific translocation domain in the effector protein. Efficient, T3SS-dependent translocation of purified YopH added in vitro was also observed when using coated Salmonella typhimurium strains, which implies that T3SS-mediated translocation of extracellular effector proteins is conserved among T3SS-dependent pathogens. Our results demonstrate that polarized T3SS-dependent translocation of proteins can be achieved through an intermediate extracellular step that can be reconstituted in vitro. These results indicate that translocation can occur by a different mechanism from the assumed single-step conduit model. PMID:21220342

Akopyan, Karen; Edgren, Tomas; Wang-Edgren, Helen; Rosqvist, Roland; Fahlgren, Anna; Wolf-Watz, Hans; Fallman, Maria

2011-01-10

68

Filamentous plant pathogen effectors in action.  

PubMed

Live-cell imaging assisted by fluorescent markers has been fundamental to understanding the focused secretory 'warfare' that occurs between plants and biotrophic pathogens that feed on living plant cells. Pathogens succeed through the spatiotemporal deployment of a remarkably diverse range of effector proteins to control plant defences and cellular processes. Some effectors can be secreted by appressoria even before host penetration, many enter living plant cells where they target diverse subcellular compartments and others move into neighbouring cells to prepare them before invasion. This Review summarizes the latest advances in our understanding of the cell biology of biotrophic interactions between plants and their eukaryotic filamentous pathogens based on in planta analyses of effectors. PMID:24129511

Giraldo, Martha C; Valent, Barbara

2013-10-16

69

Rho GTPases and their effector proteins.  

PubMed Central

Rho GTPases are molecular switches that regulate many essential cellular processes, including actin dynamics, gene transcription, cell-cycle progression and cell adhesion. About 30 potential effector proteins have been identified that interact with members of the Rho family, but it is still unclear which of these are responsible for the diverse biological effects of Rho GTPases. This review will discuss how Rho GTPases physically interact with, and regulate the activity of, multiple effector proteins and how specific effector proteins contribute to cellular responses. To date most progress has been made in the cytoskeleton field, and several biochemical links have now been established between GTPases and the assembly of filamentous actin. The main focus of this review will be Rho, Rac and Cdc42, the three best characterized mammalian Rho GTPases, though the genetic analysis of Rho GTPases in lower eukaryotes is making increasingly important contributions to this field.

Bishop, A L; Hall, A

2000-01-01

70

Organic osmotic effectors and chromatin structure.  

PubMed

Organic amino compounds (taurine, glycine) and polyols (mannitol, sorbitol) are used as osmotic effectors by most animal cells, particularly by some marine invertebrates, but also to a limit extent by mammalian cells. Using physico-chemical techniques (circular dichroism, thermal denaturation, solubility, electrophoresis and electric linear dichroism), we demonstrated that some of these effectors prevent chromatin aggregation, without histone release. The influence of glycine on chromatin aggregation, dissociation and reconstitution was thoroughly investigated. Glycine at 2 M concentration does not in itself induce chromatin dissociation; it does hinder salt-induced histone dissociation from chromatin (especially at 1.2 M NaCl) but does not impede chromatin reconstitution. Several hypothesis may be put forward to explain the action of these effectors: (i) a modulation of histone conformation; (ii) a modification of fractional DNA charge, either directly by the zwitterions (glycine, taurine) or indirectly by alteration of cations counterions hydration. The physiological relevance of our experiments is also discussed. PMID:2100521

Buche, A; Colson, P; Houssier, C

1990-12-01

71

Defective regulatory and effector T cell functions in patients with FOXP3 mutations  

PubMed Central

The autoimmune disease immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) is caused by mutations in the forkhead box protein P3 (FOXP3) gene. In the mouse model of FOXP3 deficiency, the lack of CD4+CD25+ Tregs is responsible for lethal autoimmunity, indicating that FOXP3 is required for the differentiation of this Treg subset. We show that the number and phenotype of CD4+CD25+ T cells from IPEX patients are comparable to those of normal donors. CD4+CD25high T cells from IPEX patients who express FOXP3 protein suppressed the in vitro proliferation of effector T cells from normal donors, when activated by “weak” TCR stimuli. In contrast, the suppressive function of CD4+CD25high T cells from IPEX patients who do not express FOXP3 protein was profoundly impaired. Importantly, CD4+CD25high T cells from either FOXP3+ or FOXP3– IPEX patients showed altered suppression toward autologous effector T cells. Interestingly, IL-2 and IFN-? production by PBMCs from IPEX patients was significantly decreased. These findings indicate that FOXP3 mutations in IPEX patients result in heterogeneous biological abnormalities, leading not necessarily to a lack of differentiation of CD4+CD25high Tregs but rather to a dysfunction in these cells and in effector T cells.

Bacchetta, Rosa; Passerini, Laura; Gambineri, Eleonora; Dai, Minyue; Allan, Sarah E.; Perroni, Lucia; Dagna-Bricarelli, Franca; Sartirana, Claudia; Matthes-Martin, Susanne; Lawitschka, Anita; Azzari, Chiara; Ziegler, Steven F.; Levings, Megan K.; Roncarolo, Maria Grazia

2006-01-01

72

Magnetic end effectors for space operations  

NASA Astrophysics Data System (ADS)

The Magnetic End Effector (MEE) to be flown as part of the Dexterous End Effector (DEE) flight experiment was designed to operate with the Shuttle Remote Manipulator System (SRMS). Grappling or attachment of payloads is accomplished magnetically with two fault tolerant operations. The small magnetic grapple plate weighs far less than the standard grapple fixture; allows stacking and close spacing of payloads; and eliminates secondary release mechanisms. In addition to specifics regarding the MEE, the DEE project, Magnetic Attachment Tool (MAT), RMS-Force Torque Sensor (RMS-FTS), and Targeting and Reflective Alignment Concept (TRAC) are discussed.

Monford, Leo; Carter, Edward L.

73

Cytokine signaling in the differentiation of innate effector cells  

PubMed Central

Innate effector cells, including innate effector cells of myeloid and lymphoid lineages, are crucial components of various types of immune responses. Bone marrow progenitors differentiate into many subsets of innate effector cells after receiving instructional signals often provided by cytokines. Signal transducer and activator of transcription (STATs) have been shown to be essential in the differentiation of various types of innate effector cells. In this review, we focus specifically on the differentiation of innate effector cells, particularly the role of cytokine signaling in the differentiation of innate effector cells.

Huang, Hua; Li, Yapeng; Qi, Xiaopeng

2013-01-01

74

Kinematic evaluation of end effector design  

NASA Astrophysics Data System (ADS)

The complex, many degree-of-freedom end effectors at the leading edge of technology would be unusable in the sea bottom research environment. Simpler designs are required to provide adequate reliability for subsea use. This work examines selection of end effector designs to achieve optimum grasping ability with minimal mechanical complexity. A new method of calculating grasp stability is developed, incorporating elements of previous works in the field. Programs are developed which evaluate the ability of different end effector configurations to grasp representative objects (a cube, sphere, and infinite cylinder). End effector designs considered had circular palms with fingers located at the periphery, oriented so that each pointed to the center of the palm. The program tested configurations of from 1 to 4 fingers and from 1 to 3 links per finger. Three sets of finger proportions were considered: equal length links, half length links, and anthropomorphic proportions. The 2 finger, 2 link per finger configuration was determined to be the optimum design, and the half length proportions were selected as the best set of proportions.

Edwards, Gary W.

1992-09-01

75

Effector-independent and effector-dependent learning in the discrete sequence production task  

Microsoft Academic Search

This study examined whether skill in the discrete sequence production task involves, apart from the typical effector-independent component, an effector-dependent component. To that end, 12 participants practiced two 5-key sequences, each for 1,060 trials. One group practiced with three fingers of one hand, the other group with three fingers of two hands. In a subsequent test phase, participants in both

Willem B. Verwey; David L. Wright

2004-01-01

76

Prostaglandin E1 inhibits effector T cell induction and tissue damage in experimental murine interstitial nephritis.  

PubMed Central

Immunosuppressive effects of E-series prostaglandins have been demonstrated in many in vitro assays of immune responsiveness as well as in autoimmune diseases. To explore the mechanisms underlying prostaglandin E1 (PGE1)-associated immunosuppression in autoimmunity, we treated SJL mice immunized to produce immune-mediated interstitial nephritis with PGE1, PGF2 alpha, or vehicle alone. Mice receiving PGE1 treatment do not develop interstitial nephritis, nor do they display delayed-type hypersensitivity (DTH) to the immunizing renal tubular antigen preparation. The observed immunosuppression is critically dependent on PGE1 administration during the period of effector T cell induction. We therefore investigated the effect of PGE1 on the in vitro induction of DTH effector T cells reactive to renal tubular antigens (SRTA). PGE1 inhibits effector T cell induction in a dose-dependent, reversible manner, but has no inhibitory effect on fully differentiated DTH effector cells or SRTA-reactive cell lines. The PGE1 effect is indirect and mediated via nonspecific suppressor lymphokines. This suppression can be overcome by recombinant interleukin 1 (IL-1), which suggests a mechanism related to either diminished IL-1 secretion or target cell sensitivity to IL-1. Images

Kelly, C J; Zurier, R B; Krakauer, K A; Blanchard, N; Neilson, E G

1987-01-01

77

Pneumatically Actuated Flexible Coupling end Effectors for Lapping/Polishing.  

National Technical Information Service (NTIS)

Methods and apparatus for end effectors for performing surface lapping using a robotic system are provided. In one embodiment, a lapping system includes a robotic arm and a pneumatic end effector unit. The pneumatic end effector unit includes a first base...

J. H. Wood

2004-01-01

78

Distinct regulation of effector and memory T-cell differentiation  

Microsoft Academic Search

Three major subsets of antigen-experienced T cells have been identified based on surface markers and distinct functional properties: short-lived effector T cells, central memory T cells and effector memory T cells. The precise relationship among these subsets and their mode of differentiation are still controversial. Recent studies, however, have provided compelling evidence for an early delineation of the effector versus

Axel Kallies

2008-01-01

79

Subterfuge and Manipulation: Type III Effector Proteins of Phytopathogenic Bacteria  

Microsoft Academic Search

Diverse gram-negative bacteria deliver effector proteins into the cells of their eukaryotic hosts using the type III secretion system. Collectively, these type III effector proteins function to optimize the host cell environment for bacterial growth. Type III effector proteins are essential for the virulence of Pseudomonas syringae, Xan- thomonas spp., Ralstonia solanacearum and Erwinia species. Type III secretion systems are

Sarah R. Grant; Emily J. Fisher; Jeff H. Chang; Beth M. Mole; Jeffery L. Dangl

2006-01-01

80

Legionella secreted effectors and innate immune responses  

PubMed Central

Summary Legionella pneumophila is a facultative intracellular pathogen capable of replicating in a wide spectrum of cells. Successful infection by Legionella requires the Dot/Icm type IV secretion system, which translocates a large number of effector proteins into infected cells. By co-opting numerous host cellular processes, these proteins function to establish a specialized organelle that allows bacterial survival and proliferation. Even within the vacuole, L. pneumophila triggers robust immune responses. Recent studies reveal that a subset of Legionella effectors directly target some basic components of the host innate immunity systems such as phagosome maturation. Others play essential roles in engaging the host innate immune surveillance system. This review will highlight recent progress in our understanding of these interactions and discuss implications for the study of the immune detection mechanisms.

Luo, Zhao-Qing

2012-01-01

81

Rho effectors and reorganization of actin cytoskeleton  

Microsoft Academic Search

The small GTPase Rho regulates several actomyosin-based cellular processes such as cell adhesion, cytokinesis and contraction. The biochemical mechanisms of these actions remain unknown. Recently, several GTP-Rho binding proteins were isolated. Among them, p140mDia and p160ROCK appear to work as Rho effectors mediating its action on the cytoskeleton. p140mDia induces actin polymerization by recruiting an actin binding protein, profilin, to

Shuh Narumiya; Toshimasa Ishizaki; Naoki Watanabe

1997-01-01

82

Decrease of Foxp3+ Treg cell number and acquisition of effector cell phenotype during lethal infection  

PubMed Central

Using a model of lethal oral infection with Toxoplasma gondii, we examined the fate of both induced and natural regulatory T (Treg) cells in the face of strong inflammatory responses occurring in a tolerogenic-prone environment. We found that during highly T helper 1 (Th1) cell-polarized mucosal immune responses, Treg cell numbers collapsed via multiple pathways including blockade of Treg cell induction and disruption of endogenous Treg cell homeostasis. In particular, shutdown of interleukin 2 (IL-2) in the highly Th1 cell-polarized environment triggered by infection directly contributed to Treg cell incapacity to suppress effector responses and eventually leads to immunopathogenesis. Furthermore, we found that environmental cues provided by both local dendritic cells and effector T cells can induce the expression of T-bet transcription factor and IFN-? by Treg cells. These data reveal a mechanism for Th1 cell pathogenicity that extends beyond their proinflammatory program to limit Treg cell survival.

Oldenhove, Guillaume; Bouladoux, Nicolas; Wohlfert, Elizabeth A.; Hall, Jason; Chou, David; Dos santos, Liliane; O'Brien, Shaun; Blank, Rebecca; Lamb, Erika; Natarajan, Sundar; Kastenmayer, Robin; Hunter, Christopher; Grigg, Michael E.; Belkaid, Yasmine

2009-01-01

83

Nematode effector proteins: an emerging paradigm of parasitism.  

PubMed

Phytonematodes use a stylet and secreted effectors to modify host cells and ingest nutrients to support their growth and development. The molecular function of nematode effectors is currently the subject of intense investigation. In this review, we summarize our current understanding of nematode effectors, with a particular focus on proteinaceous stylet-secreted effectors of sedentary endoparasitic phytonematodes, for which a wealth of information has surfaced in the past 10 yr. We provide an update on the effector repertoires of several of the most economically important genera of phytonematodes and discuss current approaches to dissecting their function. Lastly, we highlight the latest breakthroughs in effector discovery that promise to shed new light on effector diversity and function across the phylum Nematoda. PMID:23691972

Mitchum, Melissa G; Hussey, Richard S; Baum, Thomas J; Wang, Xiaohong; Elling, Axel A; Wubben, Martin; Davis, Eric L

2013-05-21

84

Specific In Planta Recognition of Two GKLR Proteins of the Downy Mildew Bremia lactucae Revealed in a Large Effector Screen in Lettuce.  

PubMed

Breeding lettuce (Lactuca sativa) for resistance to the downy mildew pathogen Bremia lactucae is mainly achieved by introgression of dominant downy mildew resistance (Dm) genes. New Bremia races quickly render Dm genes ineffective, possibly by mutation of recognized host-translocated effectors or by suppression of effector-triggered immunity. We have previously identified 34 potential RXLR(-like) effector proteins of B. lactucae that were here tested for specific recognition within a collection of 129 B. lactucae-resistant Lactuca lines. Two effectors triggered a hypersensitive response: BLG01 in 52 lines, predominantly L. saligna, and BLG03 in two L. sativa lines containing Dm2 resistance. The N-terminal sequences of BLG01 and BLG03, containing the signal peptide and GKLR variant of the RXLR translocation motif, are not required for in planta recognition but function in effector delivery. The locus responsible for BLG01 recognition maps to the bottom of lettuce chromosome 9, whereas recognition of BLG03 maps in the RGC2 cluster on chromosome 2. Lactuca lines that recognize the BLG effectors are not resistant to Bremia isolate Bl:24 that expresses both BLG genes, suggesting that Bl:24 can suppress the triggered immune responses. In contrast, lettuce segregants displaying Dm2-mediated resistance to Bremia isolate Bl:5 are responsive to BLG03, suggesting that BLG03 is a candidate Avr2 protein. PMID:23883357

Stassen, Joost H M; Boer, Erik den; Vergeer, Pim W J; Andel, Annemiek; Ellendorff, Ursula; Pelgrom, Koen; Pel, Mathieu; Schut, Johan; Zonneveld, Olaf; Jeuken, Marieke J W; Van den Ackerveken, Guido

2013-11-01

85

Fire Suppression  

Microsoft Academic Search

\\u000a Water sprinkler sprays (with relatively large droplet sizes) in residential and commercial structures are probably the most\\u000a well-known application of sprays in fire suppression. In more recent years, water mists (characterized by reduced droplet\\u000a sizes, which may contain additives) have been considered as a replacement for Halon 1301, the most common fire suppressant\\u000a chemical aboard aircraft and ships, but banned

C. Presser; J. C. Yang

86

Survivin as a global target of intrinsic tumor suppression networks  

PubMed Central

Despite the constant exposure to genomic insults that may lead to malignancy, cancer is surprisingly a relatively rare occurrence, and this is largely credited to an elaborate network of endogenous tumor suppression. Many effectors of tumor suppression have been identified, and their functions when activated in damaged cells have in large part been elucidated. What is less clear is whether there are common target gene(s) of tumor suppression, whose expression must be ablated in order to block transformation and preserve cellular homeostasis. Fresh experimental evidence suggests that silencing of the mitotic regulator and cell death inhibitor, survivin, is a universal requirement for successful tumor suppression in humans.

Guha, Minakshi; Altieri, Dario C.

2010-01-01

87

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.

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

2012-01-01

88

Identification of two Legionella pneumophila effectors that manipulate host phospholipids biosynthesis.  

PubMed

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

2012-11-01

89

Activation and Expansion of CD8+ T Effector Cells in Patients with Chronic Graft-Versus-Host Disease  

PubMed Central

We tested the hypothesis that changes in the phenotype of CD8+ T cells from patients with chronic graft-versus-host disease (GVHD) correlate with disease activity, and resolve or normalize in clinically tolerant patients successfully withdrawn from immune suppression therapy. No significant difference was found in the absolute CD8+ T cell counts among chronic GVHD patients, tolerant patients and healthy controls. However, compared to healthy normal controls, CD8+ T cells from chronic GVHD patients had decreased expression of the IL-7 receptor and an increase in effector T cells, Ki-67 and perforin expression and apoptosis, suggesting that activation, differentiation and proliferation of host-reactive CD8+ effector T cells is a mechanism by which chronic GVHD is sustained and persists. The increase in effector T cells was most prominent in older patients and patients who were CMV seropositive prior to transplant. Use of immune suppression therapy was associated with a decreased number of CD45RA? CD8+ effector T cells, a decreased expression of Ki-67, and an increased expression of CD95 (Fas). Together, these results demonstrate that CD8+ T cells in patients with chronic GVHD are characterized by an increased level of activation and proliferation, and an expansion of effector cells which appear to be selectively sensitive to immune suppression therapy compared to other CD8+ T cells. In GVHD-free tolerant patients, CD8+ T cells showed an increased expression of granzyme and HLA-DR molecules compared to CD8+ T cells from healthy controls, indicating that clinical tolerance in these patients can occur without full normalization of the CD8+ T cell phenotype.

Grogan, Bryan M.; Tabellini, Laura; Storer, Barry; Bumgarner, Tara E.; Astigarraga, Claudia C.; Flowers, Mary E. D.; Lee, Stephanie J.; Martin, Paul J; Warren, Edus H.; Hansen, John A.

2011-01-01

90

Regulators and effectors of siah ubiquitin ligases.  

PubMed

The Siah ubiquitin ligases are members of the RING finger E3 ligases. The Siah E3s are conserved from fly to mammals. Primarily implicated in cellular stress responses, Siah ligases play a key role in hypoxia, through the regulation of HIF-1? transcription stability and activity. Concomitantly, physiological conditions associated with varying oxygen tension often highlight the importance of Siah, as seen in cancer and neurodegenerative disorders. Notably, recent studies also point to the role of these ligases in fundamental processes including DNA damage response, cellular organization and polarity. This review summarizes the current understanding of upstream regulators and downstream effectors of Siah. PMID:23700162

Qi, Jianfei; Kim, Hyungsoo; Scortegagna, Marzia; Ronai, Ze'ev A

2013-09-01

91

TAL Effector-Nucleotide Targeter (TALE-NT) 2.0: tools for TAL effector design and target prediction  

PubMed Central

Transcription activator-like (TAL) effectors are repeat-containing proteins used by plant pathogenic bacteria to manipulate host gene expression. Repeats are polymorphic and individually specify single nucleotides in the DNA target, with some degeneracy. A TAL effector-nucleotide binding code that links repeat type to specified nucleotide enables prediction of genomic binding sites for TAL effectors and customization of TAL effectors for use in DNA targeting, in particular as custom transcription factors for engineered gene regulation and as site-specific nucleases for genome editing. We have developed a suite of web-based tools called TAL Effector-Nucleotide Targeter 2.0 (TALE-NT 2.0; https://boglab.plp.iastate.edu/) that enables design of custom TAL effector repeat arrays for desired targets and prediction of TAL effector binding sites, ranked by likelihood, in a genome, promoterome or other sequence of interest. Search parameters can be set by the user to work with any TAL effector or TAL effector nuclease architecture. Applications range from designing highly specific DNA targeting tools and identifying potential off-target sites to predicting effector targets important in plant disease.

Doyle, Erin L.; Booher, Nicholas J.; Standage, Daniel S.; Voytas, Daniel F.; Brendel, Volker P.; VanDyk, John K.; Bogdanove, Adam J.

2012-01-01

92

Multiple thermoregulatory effectors with independent central controls.  

PubMed

This review first considers how mammalian body temperature regulation evolved, and how the brain's responses to thermoregulatory challenges are likely to be organised differently from the way an engineer would design them. This is because thermoregulatory effector mechanisms would have evolved one at a time, with each being superimposed on pre-existing mechanisms. There may be no functional need for the final ensemble of control loops to be coordinated by neural cross-connections: appropriate thermal thresholds would solve the problem sufficiently. Investigations first into thermoregulatory behaviours and later into unconscious thermoregulatory mechanisms (autonomic and shivering) have led investigators to the realisation that multiple control loops exist in the brain, with each effector system apparently regulated by its own central temperature sensors. This theme is developed with reference to data on four temperature-regulated neural outflows that have been studied on anaesthetized rats under standard conditions in the authors' laboratory. Direct comparisons were made between the behaviour of sympathetic nerves supplying the tail vasculature, vessels in the proximal hairy skin, interscapular brown adipose tissue (BAT) and fusimotor fibres to hind limb muscle. All four outflows were activated by cooling the skin, and all were silenced by neuronal inhibition in the medullary raphé. Their thermal thresholds were quite different, however, as were their relative responsiveness to core temperature. This was ranked as: tail > back skin > BAT > fusimotor. These and other data indicate that the four thermoeffector outflows are driven by separate neural pathways, each regulated by independent brain temperature sensors. PMID:19949811

McAllen, Robin M; Tanaka, Mutsumi; Ootsuka, Yoichiro; McKinley, Michael J

2009-12-01

93

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

2013-08-21

94

Adenosine A2A receptor activation inhibits T helper 1 and T helper 2 cell development and effector function  

Microsoft Academic Search

Adenosine is an immunosuppressive nu- cleoside, and adenosine A2A receptors inhibit T-cell acti- vation. We investigated the role of A2A receptors in regulating T helper (Th)1- and Th2-cell development and effector function. A2A-receptor stimulation suppressed the development of T-cell receptor (TCR) -stimulated naive T cells into both Th1 and Th2 cells, as indicated by decreased IFN- production by cells developed

Balazs Csoka; Leonora Himer; Zsolt Selmeczy; E. Sylvester Vizi; Pal Pacher; Catherine Ledent; Edwin A. Deitch; Zoltan Spolarics; Zoltan H. Nemeth; Gyorgy Hasko

2008-01-01

95

Trio's Rho-specific GEF domain is the missing G?q effector in C. elegans  

PubMed Central

The G?q pathway is essential for animal life and is a central pathway for driving locomotion, egg laying, and growth in Caenorhabditis elegans, where it exerts its effects through EGL-8 (phospholipase C? [PLC?]) and at least one other effector. To find the missing effector, we performed forward genetic screens to suppress the slow growth and hyperactive behaviors of mutants with an overactive G?q pathway. Four suppressor mutations disrupted the Rho-specific guanine-nucleotide exchange factor (GEF) domain of UNC-73 (Trio). The mutations produce defects in neuronal function, but not neuronal development, that cause sluggish locomotion similar to animals lacking EGL-8 (PLC?). Strains containing null mutations in both EGL-8 (PLC?) and UNC-73 (Trio RhoGEF) have strong synthetic phenotypes that phenocopy the arrested growth and near-complete paralysis of G?q-null mutants. Using cell-based and biochemical assays, we show that activated C. elegans G?q synergizes with Trio RhoGEF to activate RhoA. Activated G?q and Trio RhoGEF appear to be part of a signaling complex, because they coimmunoprecipitate when expressed together in cells. Our results show that Trio’s Rho-specific GEF domain is a major G?q effector that, together with PLC?, mediates the G?q signaling that drives the locomotion, egg laying, and growth of the animal.

Williams, Stacey L.; Lutz, Susanne; Charlie, Nicole K.; Vettel, Christiane; Ailion, Michael; Coco, Cassandra; Tesmer, John J.G.; Jorgensen, Erik M.; Wieland, Thomas; Miller, Kenneth G.

2007-01-01

96

Trio's Rho-specific GEF domain is the missing Galpha q effector in C. elegans.  

PubMed

The Galpha(q) pathway is essential for animal life and is a central pathway for driving locomotion, egg laying, and growth in Caenorhabditis elegans, where it exerts its effects through EGL-8 (phospholipase Cbeta [PLCbeta]) and at least one other effector. To find the missing effector, we performed forward genetic screens to suppress the slow growth and hyperactive behaviors of mutants with an overactive Galpha(q) pathway. Four suppressor mutations disrupted the Rho-specific guanine-nucleotide exchange factor (GEF) domain of UNC-73 (Trio). The mutations produce defects in neuronal function, but not neuronal development, that cause sluggish locomotion similar to animals lacking EGL-8 (PLCbeta). Strains containing null mutations in both EGL-8 (PLCbeta) and UNC-73 (Trio RhoGEF) have strong synthetic phenotypes that phenocopy the arrested growth and near-complete paralysis of Galpha(q)-null mutants. Using cell-based and biochemical assays, we show that activated C. elegans Galpha(q) synergizes with Trio RhoGEF to activate RhoA. Activated Galpha(q) and Trio RhoGEF appear to be part of a signaling complex, because they coimmunoprecipitate when expressed together in cells. Our results show that Trio's Rho-specific GEF domain is a major Galpha(q) effector that, together with PLCbeta, mediates the Galpha(q) signaling that drives the locomotion, egg laying, and growth of the animal. PMID:17942708

Williams, Stacey L; Lutz, Susanne; Charlie, Nicole K; Vettel, Christiane; Ailion, Michael; Coco, Cassandra; Tesmer, John J G; Jorgensen, Erik M; Wieland, Thomas; Miller, Kenneth G

2007-10-17

97

Chronic Effects of a Salmonella Type III Secretion Effector Protein AvrA In Vivo  

PubMed Central

Background Salmonella infection is a common public health problem that can become chronic and increase the risk of inflammatory bowel diseases and cancer. AvrA is a Salmonella bacterial type III secretion effector protein. Increasing evidence demonstrates that AvrA is a multi-functional enzyme with critical roles in inhibiting inflammation, regulating apoptosis, and enhancing proliferation. However, the chronic effects of Salmonella and effector AvrA in vivo are still unknown. Moreover, alive, mutated, non-invasive Salmonella is used as a vector to specifically target cancer cells. However, studies are lacking on chronic infection with non-pathogenic or mutated Salmonella in the host. Methods/Principal Findings We infected mice with Salmonella Typhimurium for 27 weeks and investigated the physiological effects as well as the role of AvrA in intestinal inflammation. We found altered body weight, intestinal pathology, and bacterial translocation in spleen, liver, and gallbladder in chronically Salmonella-infected mice. Moreover, AvrA suppressed intestinal inflammation and inhibited the secretion of cytokines IL-12, IFN-?, and TNF-?. AvrA expression in Salmonella enhanced its invasion ability. Liver abscess and Salmonella translocation in the gallbladder were observed and may be associated with AvrA expression in Salmonella. Conclusion/Significance We created a mouse model with persistent Salmonella infection in vivo. Our study further emphasizes the importance of the Salmonella effector protein AvrA in intestinal inflammation, bacterial translocation, and chronic infection in vivo.

Lu, Rong; Wu, Shaoping; Liu, Xingyin; Xia, Yinglin; Zhang, Yong-guo; Sun, Jun

2010-01-01

98

The necrotrophic effector SnToxA induces the synthesis of a novel phytoalexin in wheat.  

PubMed

Stagonospora nodorum and Pyrenophora tritici-repentis produce the effector ToxA that interacts with the dominant susceptibility gene in wheat, Tsn1. However, the way in which ToxA induces cell death and causes disease is unclear. Here, we performed comprehensive metabolite profiling of ToxA-infiltrated wheat (Triticum aestivum) to observe the secondary metabolite response to this effector. A strong induction of secondary metabolism subsequent to SnToxA infiltration was observed, including the monoamine serotonin. We established a novel role for serotonin as a phytoalexin in wheat and demonstrated that serotonin strongly inhibited sporulation of S. nodorum. Microscopy revealed that serotonin interferes with spore formation and maturation within pycnidial structures of the fungus. Subsequent analysis of S. nodorum exposed to serotonin revealed metabolites changes previously associated with sporulation, including trehalose and alternariol. Furthermore, we identified significantly lower concentrations of serotonin during infection compared with infiltration with ToxA, providing evidence that S. nodorum may suppress plant defence. This is the first study demonstrating induction of plant secondary metabolites in response to a necrotrophic effector that have significant antifungal potential against the pathogen. While it is generally accepted that necrotrophs exploit host cell responses, the current research strengthens the notion that necrotrophs require mechanisms to overcome plant defence to survive initial stages of infection. PMID:23782173

Du Fall, Lauren A; Solomon, Peter S

2013-06-19

99

Cooperative binding of effectors by an allosteric ribozyme  

Microsoft Academic Search

An allosteric ribozyme that requires two different effectors to induce catalysis was created using modular rational design. This ribozyme construct comprises five conjoined RNA modules that operate in concert as an obligate FMN- and theophylline- dependent molecular switch. When both effectors are present, this 'binary' RNA switch self-cleaves with a rate enhancement of ?300-fold over the rate observed in the

Antony M. Jose; Garrett A. Soukup; Ronald R. Breaker

2001-01-01

100

Coordination dynamics of learning and transfer across different effector systems  

Microsoft Academic Search

If different effector systems share a common task-specific coordination dynamics, transfer and gener- alization of sensorimotor learning are predicted. Subjects learned a visually specified phase relationship with either the arms or the legs. Coordination tendencies in both effector systems were evaluated before and after practice to detect attractive states of the coordination dynamics. Results indicated that learning a novel relative

J. A. S. Kelso; P.-G. Zanone

2002-01-01

101

Hand to mouth: automatic imitation across effector systems.  

PubMed

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 Experiment 3. Each of these imperative stimuli was accompanied by task-irrelevant action images depicting a hand or mouth opening or closing. In relation to the response, the irrelevant stimulus was movement compatible or movement incompatible, and effector compatible or effector incompatible. A movement compatibility effect was observed for both hand and mouth responses. These movement compatibility effects were present when the irrelevant stimulus was effector compatible and when it was effector incompatible, but were smaller when the irrelevant stimulus and response effectors were incompatible. Consistent with the associative sequence learning (ASL) model of imitation, these findings indicate that automatic imitation is partially effector dependent and therefore that the effector dependence of intentional imitation reflects, at least in part, the nature of the mechanisms that mediate visuomotor translation for imitation. PMID:20731510

Leighton, Jane; Heyes, Cecilia

2010-10-01

102

Oomycete and fungal effector entry, a microbial Trojan horse.  

PubMed

Oomycete and fungal symbionts have significant impacts on most commercially important crop and forest species, and on natural ecosystems, both negatively as pathogens and positively as mutualists. Symbiosis may be facilitated through the secretion of effector proteins, some of which modulate a variety of host defense mechanisms. A subset of these secreted proteins are able to translocate into host cells. In the oomycete pathogens, two conserved N-terminal motifs, RXLR and dEER, mediate translocation of effector proteins into host cells independent of any pathogen-encoded machinery. An expanded 'RXLR-like' motif [R/K/H]X[L/M/I/F/Y/W]X has been used to identify functional translocation motifs in host-cell-entering fungal effector proteins from pathogens and a mutualist. The RXLR-like translocation motifs were required for the fungal effectors to enter host cells in the absence of any pathogen-encoded machinery. Oomycete and fungal effectors with RXLR and RXLR-like motifs can bind phospholipids, specifically phosphatidylinositol-3-phosphate (PtdIns-3-P). Effector-PtdIns-3-P binding appears to mediate cell entry via lipid raft-mediated endocytosis, and could be blocked by sequestering cell surface PtdIns-3-P or by utilizing inositides that competitively inhibit effector binding to PtdIns-3-P. These findings suggest that effector blocking technologies could be developed and utilized in a variety of important crop species against a broad spectrum of plant pathogens. PMID:22403824

Kale, Shiv D

2012-03-01

103

Plant immunity: a lesson from pathogenic bacterial effector proteins  

Microsoft Academic Search

Summary Phytopathogenic bacteria inject an array of effec- tor proteins into host cells to alter host physiology and assist the infection process. Some of these effectors can also trigger disease resistance as a result of recognition in the plant cell by cyto- plasmic immune receptors. In addition to effector- triggered immunity, plants immunity can be triggered upon the detection of

Haitao Cui; Tingting Xiang; Jian-Min Zhou

2009-01-01

104

Acireductone Dioxygenase 1 (ARD1) Is an Effector of the Heterotrimeric G Protein ? Subunit in Arabidopsis*  

PubMed Central

Heterotrimeric G protein complexes are conserved from plants to mammals, but the complexity of each system varies. Arabidopsis thaliana contains one G?, one G? (AGB1), and at least three G? subunits, allowing it to form three versions of the heterotrimer. This plant model is ideal for genetic studies because mammalian systems contain hundreds of unique heterotrimers. The activation of these complexes promotes interactions between both the G? subunit and the G?? dimer with enzymes and scaffolds to propagate signaling to the cytoplasm. However, although effectors of G? and G? are known in mammals, no G? effectors were previously known in plants. Toward identifying AGB1 effectors, we genetically screened for dominant mutations that suppress G?-null mutant (agb1-2) phenotypes. We found that overexpression of acireductone dioxygenase 1 (ARD1) suppresses the 2-day-old etiolated phenotype of agb1-2. ARD1 is homologous to prokaryotic and eukaryotic ARD proteins; one function of ARDs is to operate in the methionine salvage pathway. We show here that ARD1 is an active metalloenzyme, and AGB1 and ARD1 both control embryonic hypocotyl length by modulating cell division; they also may contribute to the production of ethylene, a product of the methionine salvage pathway. ARD1 physically interacts with AGB1, and ARD enzymatic activity is stimulated by AGB1 in vitro. The binding interface on AGB1 was deduced using a comparative evolutionary approach and tested using recombinant AGB1 mutants. A possible mechanism for AGB1 activation of ARD1 activity was tested using directed mutations in a loop near the substrate-binding site.

Friedman, Erin J.; Wang, Helen X.; Jiang, Kun; Perovic, Iva; Deshpande, Aditi; Pochapsky, Thomas C.; Temple, Brenda R. S.; Hicks, Stephanie N.; Harden, T. Kendall; Jones, Alan M.

2011-01-01

105

The Salmonella effector AvrA mediates bacterial intracellular survival during infection in vivo  

PubMed Central

SUMMARY The enteric pathogen Salmonella typhimurium secretes the preformed AvrA effector protein into host cells. This acetyltransferase has been shown to modulate mammalian intestinal immune and survival responses by inhibition of JNK MAPK. To study the role of this effector in natural enteric infection, we used a mouse model to compare wild type Salmonella typhimurium to an isogenic AvrA null Salmonella mutant. Salmonella lacking AvrA induced increased intestinal inflammation, more intense systemic cytokine responses, and increased apoptosis in epithelial cells. Increased apoptosis was also observed in extra epithelial macrophages. AvrA null infected mice consistently showed higher bacterial burden within mucosal lymphoid tissues, spleen and liver by 5 days post infection, which indicated a more severe clinical course. To study the molecular mechanisms involved, recombinant adenoviruses expressing AvrA or mutant AvrA proteins were constructed, which showed appropriate expression and mediated the expected inhibition of JNK signaling. Cultured epithelial cells and macrophages transduced with AvrA expressing adenovirus were protected from apoptosis induced by exogenous stimuli. In conclusion, the results demonstrated that Salmonella AvrA modulates survival of infected macrophages likely via JNK suppression, and prevents macrophage death and rapid bacterial dissemination. AvrA suppression of apoptosis in infected macrophages may allow for establishment of a stable intracellular niche typical of intracellular pathogens.

Wu, Huixia; Jones, Rheinallt M.; Neish, Andrew S.

2011-01-01

106

Action selection in multi-effector decision making.  

PubMed

Decision making and reinforcement learning over movements suffer from the curse of dimensionality: the space of possible movements is too vast to search or even represent in its entirety. When actions involve only a single effector, this problem can be ameliorated by considering that effector separately; accordingly, the brain's sensorimotor systems can subdivide choice by representing values and actions separately for each effector. However, for many actions, such as playing the piano, the value of an action by an effector (e.g., a hand) depends inseparably on the actions of other effectors. By definition, the values of such coordinated multi-effector actions cannot be represented by effector-specific action values, such as those that have been most extensively investigated in parietal and premotor regions. For such actions, one possible solution is to choose according to more abstract valuations over different goods or options, which can then be mapped onto the necessary motor actions. Such an approach separates the learning and decision problem, which will often be lower-dimensional than the space of possible movements, from the multi-effector movement planning problem. The ventromedial prefrontal cortex (vmPFC) is thought to contain goods-based value signals, so we hypothesized that this region might preferentially drive multi-effector action selection. To examine how the brain solves this problem, we used fMRI to compare patterns of BOLD activity in humans during reward learning tasks in which options were selected through either unimanual or bimanual actions, and in which the response requirements in the latter condition inseparably coupled valuation across both hands. We found value signals in the bilateral medial motor cortex and vmPFC, and consistent with previous studies, the medial motor value signals contained contra-lateral biases indicating effector-specificity, while the vmPFC value signals did not exhibit detectable effector specificity. Although neither region's value signaling differed significantly between bimanual and unimanual conditions, the vmPFC value region showed greater connectivity with the medial motor cortex during bimanual than during unimanual choices. The specific region implicated, the anterior mid-cingulate cortex, is thought to act as a hub that links subjective value signals to motor control centers. These results are consistent with the idea that while valuation for unilateral actions may be subserved by an effector-specific network, complex multi-effector actions preferentially implicate communication between motor regions and prefrontal regions, which may reflect increased top-down input into motor regions to guide action selection. PMID:23228512

Madlon-Kay, Seth; Pesaran, Bijan; Daw, Nathaniel D

2012-12-07

107

Proline-rich tyrosine kinase-2 is critical for CD8 T-cell short-lived effector fate  

PubMed Central

T-cell interactions with antigen-presenting cells are important for CD8 T-cell effector or memory fate determination. The integrin leukocyte function-associated antigen-1 (LFA-1) mediates T-cell adhesion but the contribution of LFA-1–induced signaling pathways to T-cell responses is poorly understood. Here we demonstrate that proline-rich tyrosine kinase-2 (PYK2) deficiency impairs CD8 T-cell activation by synergistic LFA-1 and T-cell receptor stimulation. Furthermore, PYK2 is essential for LFA-1-mediated CD8 T-cell adhesion and LFA-1 costimulation of CD8 T-cell migration. During lymphocytic choriomeningitis virus infection in vivo, PYK2 deficiency results in a specific loss of short-lived effector CD8 T cells but does not affect memory-precursor CD8 T-cell development. Similarly, lack of LFA-1 primarily impairs the generation of short-lived effector cells. Thus, PYK2 facilitates LFA-1–dependent CD8 T-cell responses and promotes CD8 T-cell short-lived effector fate, suggesting that PYK2 may be an interesting therapeutic target to suppress exacerbated CD8 T-cell responses.

Beinke, Soren; Phee, Hyewon; Clingan, Jonathan M.; Schlessinger, Joseph; Matloubian, Mehrdad; Weiss, Arthur

2010-01-01

108

Immune effector mechanisms in myocardial pathologies.  

PubMed

It is now well established that immune effector mechanisms contribute to cardiac dysfunction in several heart diseases, including myocarditis and the associated dilated cardiomyopathy, heart transplant rejection and Chagas' disease. These and other pathologies, in which cellular immunity plays an important role, contribute to morbidity and mortality world-wide. As a result of numerous studies performed in this exciting field, two major mechanisms of lymphocytotoxicity have been proposed: a secretory mechanism in which perforin and granzymes are key players, and a non-secretory mechanism involving Fas/FasL activation. While the common notion is that CTL-myocyte interaction, perforin- or Fas-based, inevitably results in target cell apoptotic death, the objective of this review is to consider the concept of non-apoptotic consequences of CTL-target cell interaction. It is proposed that depending on the myocyte status as well as on the fine balance between pro- and anti-apoptotic factors, CTL-myocyte interaction may result in a non-apoptotic, potentially reversible sustained damage to the myocytes, thus contributing to immune-mediated cardiac dysfunction. PMID:10851260

Binah, O

2000-07-01

109

Rack Insertion End Effector (RIEE) guidance  

NASA Astrophysics Data System (ADS)

NASA-KSC has developed a mechanism to handle and insert Racks into the Space Station Logistic Modules. This mechanism consists of a Base with 3 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. During the 1993 NASA-ASEE Summer Faculty Fellowship Program at KSC, I designed an Active Vision (Camera) Arrangement and developed an algorithm to determine (1) the displacements required by the Room for its initial positioning and (2) the rotations required at the five hand-wheels of the RIEE, for the insertion of the Rack, using the centroids fo the Camera Images of the Location Targets in the Logistic Module. Presently, during the summer of '94, I completed the preliminary design of an easily portable measuring instrument using encoders to obtain the 3-Dimensional Coordinates of Location Targets in the Logistics Module relative to the RIEE mechanism frame. The algorithm developed in '93 can use the output of this instrument also. Simplification of the '93 work and suggestions for the future work are discussed.

Malladi, Narasimha S.

1994-10-01

110

Bioprospecting open reading frames for Peptide effectors.  

PubMed

Recent successes in the development of small-molecule antagonists of protein-protein interactions designed based on co-crystal structures of peptides bound to their biological targets confirm that short peptides derived from interacting proteins can be high-value ligands for pharmacologic validation of targets and for identification of druggable sites. Evolved sequence space is likely to be enriched for interacting peptides, but identifying minimal peptide effectors within genomic sequence can be labor intensive. Here we describe the use of incremental truncation to diversify genetic material on the scale of open reading frames into comprehensive libraries of constituent peptides. The approach is capable of generating peptides derived from both continuous and discontinuous sequence elements, and is compatible with the expression of free linear or backbone cyclic peptides, with peptides tethered to amino- or carboxyl-terminal fusion partners or with the expression of peptides displayed within protein scaffolds (peptide aptamers). Incremental truncation affords a valuable source of molecular diversity to interrogate the druggable genome or evaluate the therapeutic potential of candidate genes. PMID:24146398

Xiong, Ling; Scott, Charles

2014-01-01

111

Interchangeable End Effector Tools Utilized on the Protoflight Manipulator Arm.  

National Technical Information Service (NTIS)

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 interchangea...

1987-01-01

112

Programmer's Guide to the Sensory-Effector Interface.  

National Technical Information Service (NTIS)

A Sensory-effector interface performs three major functions: maintaining its own copy of the world data structures, selecting information from these structures appropriate to the perception capabilities of a particular organism, and translating actions ta...

K. Barnett

1987-01-01

113

Expressing the Erwinia amylovora type III effector DspA/E in the yeast Saccharomyces cerevisiae strongly alters cellular trafficking.  

PubMed

Erwinia amylovora is responsible for fire blight, a necrotic disease of apples and pears. E. amylovora relies on a type III secretion system (T3SS) to induce disease on host plants. DspA/E belongs to the AvrE family of type III effector. Effectors of the AvrE family are injected via the T3SS in plant cell and are important to promote bacterial growth following infection and to suppress plant defense responses. Their mode of action in the plant cells is unknown. Here we study the physiological effects induced by dspA/E expression in the yeast Saccharomyces cerevisiae. Expression of dspA/E in the yeast inhibits cell growth. This growth inhibition is associated with perturbations of the actin cytoskeleton and endocytosis. PMID:23650572

Siamer, Sabrina; Patrit, Oriane; Fagard, Mathilde; Belgareh-Touzé, Naïma; Barny, Marie-Anne

2011-11-11

114

Kinetics of the relation between suppressor and effector mechanisms in contact sensitivity in the guinea-pig.  

PubMed Central

Cyclophosphamide (300 mg/kg) given before or up to 2 days after sensitization, induces increased contact skin reactions at 8 days. Reactions were suppressed with cyclophosphamide (CY) given between 3 and 5 days after sensitization; reactivity returned on day 10. CY, given on days 6 to 8, only suppressed reactions when skin tests were made 4 days later. This temporary depression of contact sensitivity corresponds with the maximal reduction of peripheral blood lymphocytes. CY given 1-2 days after DNFB produced decreased T-cell proliferation in local lymph nodes 4 days after sensitization. CY given 3 days after DNFB produced maximal T-cell suppression on 5 day nodes. Massive increase in T-cell proliferation in 5 day nodes occurred when CY was given on the day of sensitization or the day before. Thus CY given around sensitization acts mainly on suppressor cells whereas given later, the action is principally on the effector functions.

Parker, D; Turk, J L

1982-01-01

115

Changes in frequency of HIV-1-specific cytotoxic T cell precursors and circulating effectors after combination antiretroviral therapy in children.  

PubMed

Combination antiretroviral therapy has had a major role in reducing human immunodeficiency virus type 1 (HIV-1) plasma viral loads in HIV-1-infected adults but a variable effect in infants, in whom complete viral suppression appears to be less readily achieved. In adults, after the reduction in plasma viremia, there is a decrease in the numbers of circulating cytotoxic T cell (CTL) effectors and precursors in the majority of patients. This longitudinal study assessed the effect of combination drug therapy on the frequency of HIV-1-specific CTL responses in 8 HIV-1-infected children. Following treatment, the frequency of HIV-1-specific CTL responses initially increased, especially in children with incomplete viral suppression but with increasing CD4+ cell counts. In children with complete viral suppression, the frequency of HIV-1-specific CTL responses decreased, suggesting that viral replication is required to maintain CTL responses in the systemic circulation. PMID:10395850

Spiegel, H M; DeFalcon, E; Ogg, G S; Larsson, M; Beadle, T J; Tao, P; McMichael, A J; Bhardwaj, N; O'Callaghan, C; Cox, W I; Krasinski, K; Pollack, H; Borkowsky, W; Nixon, D F

1999-08-01

116

Prospects for functional analysis of effectors from cereal rust fungi  

Microsoft Academic Search

With the advancement of several Puccinia genome sequencing projects, along with gene expression data and methods for predicting secreted proteins, it is now possible\\u000a to predict many effector proteins from the cereal rusts. Biological assays that can be conducted in a relatively high throughput\\u000a fashion are necessary to assign specific functions, such as avirulence. Biolistic delivery of potential effectors is

Chuntao Yin; Scot Hulbert

2011-01-01

117

Advanced Aerodynamic Design of Passive Porosity Control Effectors  

Microsoft Academic Search

Abstract 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 lowspeed, high angle of attack condition. Aerodynamic analysis was ,conducted ,using the NASA Langley

C. A. Hunter; S. A. Viken; R. M. Wood; S. X. S. Bauer

2001-01-01

118

Design, testing and evaluation of latching end effector  

NASA Astrophysics Data System (ADS)

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.

1995-05-01

119

Dissecting paracrine effectors for mesenchymal stem cells.  

PubMed

There has been increasing interest in the application of mesenchymal stem cells (MSCs) in regenerative medicine in recent years. In this context, the beneficial effects of MSCs have been ascribed mainly to a paracrine action rather than to direct replacement of the injured tissue. Indeed, MSCs produce a great variety of trophic and immunomodulatory factors. In this chapter, we provide an overview of growth factors and chemokines involved in stimulation of cell proliferation, inhibition of apoptosis, enhancement of angiogenesis, and suppression of inflammatory and immune response. In addition, we discuss the emerging role of the extracellular vesicles released from MSCs as possible paracrine mediators. PMID:22968371

Bruno, Stefania; Collino, Federica; Tetta, Ciro; Camussi, Giovanni

2013-01-01

120

The RalGEF-Ral Effector Signaling Network  

PubMed Central

The high frequency of RAS mutations in human cancers (33%) has stimulated intense interest in the development of anti-Ras inhibitors for cancer therapy. Currently, the major focus of these efforts is centered on inhibitors of components involved in Ras downstream effector signaling. In particular, more than 40 inhibitors of the Raf-MEK-ERK mitogen-activated protein kinase cascade and phosphoinositide 3-kinase-AKT-mTOR effector signaling networks are currently under clinical evaluation. However, these efforts are complicated by the fact that Ras can utilize at least 9 additional functionally distinct effectors, with at least 3 additional effectors with validated roles in Ras-mediated oncogenesis. Of these, the guanine nucleotide exchange factors of the Ras-like (Ral) small GTPases (RalGEFs) have emerged as important effectors of mutant Ras in pancreatic, colon, and other cancers. In this review, we summarize the evidence for the importance of this effector pathway in cancer and discuss possible directions for therapeutic inhibition of aberrant Ral activation and signaling.

Neel, Nicole F.; Martin, Timothy D.; Stratford, Jeran K.; Zand, Tanya P.; Reiner, David J.; Der, Channing J.

2011-01-01

121

Adenosine A2A receptor activation inhibits T helper 1 and T helper 2 cell development and effector function  

PubMed Central

Adenosine is an immunosuppressive nucleoside, and adenosine A2A receptors inhibit T-cell activation. We investigated the role of A2A receptors in regulating T helper (Th)1- and Th2-cell development and effector function. A2A-receptor stimulation suppressed the development of T-cell receptor (TCR) -stimulated naive T cells into both Th1 and Th2 cells, as indicated by decreased IFN-? production by cells developed under Th1-skewing conditions and decreased interleukin (IL) -4, IL-5, and IL-10 production by cells developed under Th2-skewing conditions. Using A2A receptor-deficient mice, we demonstrate that A2A receptor activation inhibits Th1- and Th2-cell development by decreasing the proliferation and IL-2 production of naive T cells, irrespective of whether the cells are expanded under Th1- or Th2-skewing environment. Using in vivo established Th1 and Th2 cells, we further demonstrate the nonselective nature of A2A receptor-mediated immunosuppressive effects, because A2A receptor activation decreased IFN-? and IL-4 secretion and mRNA level of TCR-stimulated effector Th1 and Th2 cells, respectively. A2A receptor mRNA expression in both Th1 and Th2 effector cells increased following TCR stimulation. In summary, these data demonstrate that A2A receptor activation has strong inhibitory actions during early developmental, as well as late effector, stages of Th1- and Th2-cell responses.—Csóka, B., Himer, L., Selmeczy, Z., Vizi, E. S., Pacher, P., Ledent, C., Deitch, E. A., Spolarics, Z., Németh, Z. H., Haskó, G. Adenosine A2A receptor activation inhibits T helper 1 and T helper 2 cell development and effector function.

Csoka, Balazs; Himer, Leonora; Selmeczy, Zsolt; Vizi, E. Sylvester; Pacher, Pal; Ledent, Catherine; Deitch, Edwin A.; Spolarics, Zoltan; Nemeth, Zoltan H.; Hasko, Gyorgy

2008-01-01

122

Molecular Mechanisms of Treg-Mediated T Cell Suppression  

PubMed Central

CD4+CD25highFoxp3+ regulatory T cells (Tregs) can suppress other immune cells and, thus, are critical mediators of peripheral self-tolerance. On the one hand, Tregs avert autoimmune disease and allergies. On the other hand, Tregs can prevent immune reactions against tumors and pathogens. Despite the importance of Tregs, the molecular mechanisms of suppression remain incompletely understood and controversial. Proliferation and cytokine production of CD4+CD25? conventional T cells (Tcons) can be inhibited directly by Tregs. In addition, Tregs can indirectly suppress Tcon activation via inhibition of the stimulatory capacity of antigen presenting cells. Direct suppression of Tcons by Tregs can involve immunosuppressive soluble factors or cell contact. Different mechanisms of suppression have been described, so far with no consensus on one universal mechanism. Controversies might be explained by the fact that different mechanisms may operate depending on the site of the immune reaction, on the type and activation state of the suppressed target cell as well as on the Treg activation status. Further, inhibition of T cell effector function can occur independently of suppression of proliferation. In this review, we summarize the described molecular mechanisms of suppression with a particular focus on suppression of Tcons and rapid suppression of T cell receptor-induced calcium (Ca2+), NFAT, and NF-?B signaling in Tcons by Tregs.

Schmidt, Angelika; Oberle, Nina; Krammer, Peter H.

2012-01-01

123

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.

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

2009-01-01

124

Tim-1 stimulation of dendritic cells regulates the balance between effector and regulatory T cells  

PubMed Central

Summary We show that Tim-1, initially reported to be expressed on CD4+ T cells, is constitutively expressed on dendritic cells (DC) and that its expression further increases after DC maturation. Tim-1 signaling into DC upregulates costimulatory molecule expression and proinflammatory cytokine production, thereby promoting effector T cell responses, while inhibiting Foxp3+ Treg responses. By contrast, Tim-1 signaling in T cells only regulates Th2 responses. Using a high-avidity/agonistic anti-Tim-1 antibody as a co-adjuvant enhances the immunogenic function of DC, decreases the suppressive function of Treg cells, and substantially increases proinflammatory Th17 responses in vivo. The treatment with high-but not low-, avidity anti-Tim-1 not only worsens experimental autoimmune encephalomyelitis (EAE) in susceptible mice but also breaks tolerance and induces EAE in a genetically resistant strain of mice. These findings indicate that Tim-1 has an important role in regulating DC function, and thus shifts the balance between effector and regulatory T cells towards an enhanced immune response. By understanding the mechanisms by which Tim-1 regulates DC and T cell responses, we may clarify the potential utility of Tim-1 as a target of therapy against autoimmunity, cancer and infectious diseases.

Xiao, Sheng; Zhu, Bing; Jin, Hulin; Zhu, Chen; Umetsu, Dale T.; DeKruyff, Rosemarie H.; Kuchroo, Vijay K.

2011-01-01

125

Two-dimensional analysis of human lymphocyte proteins: I. An assay for lymphocyte effectors  

SciTech Connect

We describe an assay for lymphocyte effectors that is capable of establishing the existence of regulators of lymphocyte gene expression (including post-transcriptional control and protein processing) and has the ability to characterize the response at the molecular level. The hypothesis that circulating effector substances excreted through the kidney can be actively present in human urine was tested with this assay. Thus, biologically active protein molecules in urine were detected at concentrations of less than 1 mg/L and over a wide range of dilutions. Activities were detected and quantiated by culturing human lymphocytes with human urinary proteins in the presence of (/sup 35/S)methionine and subsequently analyzing the labeled lymphocyte proteins by two-dimensional gel electrophoresis. Thus, protein analysis by two-dimensional gels was used to indirectly detect changes produced in cultured lymphocytes after exposure to regulatory molecules. Proteins or sets of lymphocyte proteins appeared or disappeared after exposure to normal or pathological human urinary proteins. Normal human urinary proteins triggered the appearance of sets of proteins referred to by number as the Urocon proteins and suppressed the synthesis of protein sets referred to as Urocof proteins. In addition to the normal alterations described, urinary proteins from individuals with influenza or acute leukemia and after renal transplantation were capable of inducing unique alterations in lymphocyte patterns.

Willard, K.E.; Anderson, N.G.

1981-08-01

126

Effector and suppressor circuits of the immune response are activated in vivo by different mechanisms.  

PubMed Central

The application of fluorescein isothiocyanate (FITC) onto the skin of mice induces a contact hypersensitivity immune response. Lymph nodes draining the skin painted with FITC contain fluorescent cells that induce contact hypersensitivity to FITC when injected into normal mice. The antigen-presenting cells responsible for activating the effector pathway of the contact hypersensitivity response express Ia histocompatibility determinants and are resistant to inactivation with gamma-radiation. Exposing the skin to low doses of UV radiation (280-320 nm) before the application of FITC suppresses the contact hypersensitivity response to FITC. Cells present in the draining lymph nodes of these mice induce suppressor T lymphocytes when injected into normal recipients. The inducer cells in the draining lymph nodes are Thy 1+, Ia- and are inactivated by gamma-radiation. These studies demonstrate that different mechanisms are involved in the in vivo activation of effector and suppressor immune responses, and they suggest that the mode of initial antigen presentation determines which immunologic circuit will be activated in response to a contact-sensitizing antigen.

Okamoto, H; Kripke, M L

1987-01-01

127

Effector-triggered innate immunity contributes Arabidopsis resistance to Xanthomonas campestris.  

PubMed

Xanthomonas campestris pv. campestris, the causal agent of black rot disease, depends on its type III secretion system (TTSS) to infect cruciferous plants, including Brassica oleracea, B. napus and Arabidopsis. Previous studies on the Arabidopsis-Pseudomonas syringae model pathosystem have indicated that a major function of TTSS from virulent bacteria is to suppress host defences triggered by pathogen-associated molecular patterns. Similar analyses have not been made for the Arabidopsis-X. campestris pv. campestris pathosystem. In this study, we report that X. campestris pv. campestris strain 8004, which is modestly pathogenic on Arabidopsis, induces strong defence responses in Arabidopsis in a TTSS-dependent manner. Furthermore, the induction of defence responses and disease resistance to X. campestris pv. campestris strain 8004 requires NDR1 (NON-RACE-SPECIFIC DISEASE RESISTANCE1), RAR1 (required for Mla12 resistance) and SGT1b (suppressor of G2 allele of skp1), suggesting that effector-triggered immunity plays a large role in resistance to this strain. Consistent with this notion, AvrXccC, an X. campestris pv. campestris TTSS effector protein, induces PR1 expression and confers resistance in Arabidopsis in a RAR1- and SGT1b-dependent manner. In rar1 and sgt1b mutants, AvrXccC acts as a virulence factor, presumably because of impaired resistance gene function. PMID:21029323

Rong, Wei; Feng, Feng; Zhou, Jianmin; He, Chaozu

2010-11-01

128

Studies on induction and effector functions of concanavalin a-induced suppressor cells that limit TCGF production  

SciTech Connect

The cellular mechanisms regulating T-cell growth factor (TCGF) production in Con A-stimulated cultures have been invstigated. Normal spleen cells, activated by Con A for 24 hr, develop suppressive cells that inhibit de novo production of TCGF by fresh spleen cells. Effector cells mediating suppression are nonadherent, radioresistant, Lyt-2-positive T cells. The induction of suppressor cells is radiosensitive and it requires 18 hr. The kinetics of suppressor cell induction parallels very closely the termination of TCGF production in situ, suggesting the major importance of this mechanism in the control of TCGF production. Reculture of 24-hr Con A-activated cells in the absence of Con A for 24 to 72 hr results in a gradual loss of suppressive activity that can be recalled by readdition of Con A with the same kinetics found in fresh spleen cells. In addition, de novo production of TCGF is readily induced in such cultures upon restimulation with Con A, demonstrating that abrogation of TCGF-production in primary cultures is due to suppression and not to lectin-dependent killing of the TCGF-producing T cells. Measurements of suppressive activity of Con A-activated cells after expansion in TCGF excludes that suppressor cells act by absorption or removal of TCGF produced at normal rates. Direct, reversible suppression of TCGF-producing cells by T lymphocytes appears, therefore, to constitute a major mechanism by which cytotoxic T cell responses are regulated.

Gullberg, M.; Larsson, E.L.

1982-02-01

129

Salmonella Effectors: Important players modulating host cell function during infection  

PubMed Central

Summary Salmonella enterica serovar Typhimurium (S. Typhimurium) is a Gram-negative facultative foodborne pathogen that causes gastroenteritis in humans. This bacterium has evolved a sophisticated machinery to alter host cell function critical to its virulence capabilities. Central to S. Typhimurium pathogenesis are two Type three secretion systems (T3SS) encoded within pathogenicity islands SPI-1 and SPI-2 that are responsible for the secretion and translocation of a set of bacterial proteins termed effectors into host cells with the intention of altering host cell physiology for bacterial entry and survival. Thus, once delivered by the T3SS, the secreted effectors play critical roles in manipulating the host cell to allow for bacteria invasion, induction of inflammatory responses, and the assembly of an intracellular protective niche created for bacterial survival and replication. Emerging evidence indicates that these effectors are modular proteins consisting of distinct functional domains/motifs that are utilized by the bacteria to activate intracellular signaling pathways modifying host cell function. Also, recently reported are the dual functionality of secreted effectors and the concept of “terminal reassortment”. Herein, we highlight some of the nascent concepts regarding Salmonella effectors in the context infection.

Agbor, Terence A.; McCormick, Beth A.

2012-01-01

130

Isolation of Rho GTPase effector pathways during axon development.  

PubMed

The Rho GTPases Rac1 and Cdc42 have been implicated in the regulation of axon outgrowth and guidance. However, the downstream effector pathways through which these GTPases exert their effects on axon development are not well characterized. Here, we report that axon outgrowth defects within specific subsets of motoneurons expressing constitutively active Drosophila Rac1 largely persist even with the addition of an effector-loop mutation to Rac1 that disrupts its ability to bind to p21-activated kinase (Pak) and other Cdc42/Rac1 interactive-binding (CRIB)-motif effector proteins. While hyperactivation of Pak itself does not lead to axon outgrowth defects as when Rac1 is constitutively activated, live analysis reveals that it can alter filopodial activity within specific subsets of neurons similar to constitutive activation of Cdc42. Moreover, we show that the axon guidance defects induced by constitutive activation of Cdc42 persist even in the absence of Pak activity. Our results suggest that (1) Rac1 controls axon outgrowth through downstream effector pathways distinct from Pak, (2) Cdc42 controls axon guidance through both Pak and other CRIB effectors, and (3) Pak's primary contribution to in vivo axon development is to regulate filopodial dynamics that influence growth cone guidance. PMID:14550791

Kim, Michael D; Kamiyama, Daichi; Kolodziej, Peter; Hing, Huey; Chiba, Akira

2003-10-15

131

Phytopathogen type III effectors as probes of biological systems.  

PubMed

Bacterial phytopathogens utilize a myriad of virulence factors to modulate their plant hosts in order to promote successful pathogenesis. One potent virulence strategy is to inject these virulence proteins into plant cells via the type III secretion system. Characterizing the host targets and the molecular mechanisms of type III secreted proteins, known as effectors, has illuminated our understanding of eukaryotic cell biology. As a result, these effectors can serve as molecular probes to aid in our understanding of plant cellular processes, such as immune signalling, vesicle trafficking, cytoskeleton stability and transcriptional regulation. Furthermore, given that effectors directly and specifically interact with their targets within plant cells, these virulence proteins have enormous biotechnological potential for manipulating eukaryotic systems. PMID:23433088

Lee, Amy Huei-Yi; Middleton, Maggie A; Guttman, David S; Desveaux, Darrell

2013-02-25

132

Development and testing of the cooling coil cleaning end effector  

SciTech Connect

The Retrieval Process Development and Enhancement (KPD{ampersand}E) program has developed and tested an end effector to support the waste retrieval mission at the Idaho National Engineering and Environmental Laboratory (INEEL). The end effector was developed specifically to remove a sticky waste material from the cooling coils in the High Level Liquid Waste (HLLW) tank, and to vacuum up a sediment layer that has settled beneath the cooling coils. An extensive testing program was conducted in the hydraulic test bed (HTB) at the Pacific Northwest National Laboratory (PNNL) to evaluate the performance of the end effector under simulated in-tank conditions. A mock up of the cooling coils was installed in the test bed tank, and simulated waste materials were included to represent the sticky waste on the tubes and the particulate waste settled beneath them. The testing program focused on assessing long-duration mining strategies for cleaning the cooling coils and removing the particulate waste forms. The report describes the results of the end effector testing program at PNNL. Section 2 describes the physical characteristics of the HLLW tanks, including the layout of the cooling coils, and it also describes what is known of the waste forms in the tanks. Section 3 describes the cleaning and retrieval strategy that was used in developing the end effector design. Section 4 describes the cooling coil mockup in the hydraulic test bed. Section 5 discusses the rationale used in selecting the simulants for the tarry waste and particulate waste forms. Section 6 describes the tests that were performed to evaluate cleaning of the cooling coils and retrieval of the particulate simulant. Section 7 summarizes the cleaning and retrieval tests, assesses the relative importance of cleaning the cooling coils and retrieving the particulate waste, and suggests modifications that would simplify the end effector design.

Johnson, K.I.; Mullen, O.D.; Powell, M.R.; Daly, D.S.; Engel, D.W.

1997-09-30

133

Identification of Anaplasma marginale Type IV Secretion System Effector Proteins  

PubMed Central

Background Anaplasma marginale, an obligate intracellular alphaproteobacterium in the order Rickettsiales, is a tick-borne pathogen and the leading cause of anaplasmosis in cattle worldwide. Complete genome sequencing of A. marginale revealed that it has a type IV secretion system (T4SS). The T4SS is one of seven known types of secretion systems utilized by bacteria, with the type III and IV secretion systems particularly prevalent among pathogenic Gram-negative bacteria. The T4SS is predicted to play an important role in the invasion and pathogenesis of A. marginale by translocating effector proteins across its membrane into eukaryotic target cells. However, T4SS effector proteins have not been identified and tested in the laboratory until now. Results By combining computational methods with phylogenetic analysis and sequence identity searches, we identified a subset of potential T4SS effectors in A. marginale strain St. Maries and chose six for laboratory testing. Four (AM185, AM470, AM705 [AnkA], and AM1141) of these six proteins were translocated in a T4SS-dependent manner using Legionella pneumophila as a reporter system. Conclusions The algorithm employed to find T4SS effector proteins in A. marginale identified four such proteins that were verified by laboratory testing. L. pneumophila was shown to work as a model system for A. marginale and thus can be used as a screening tool for A. marginale effector proteins. The first T4SS effector proteins for A. marginale have been identified in this work.

Brayton, Kelly A.; Beare, Paul A.; Brown, Wendy C.; Heinzen, Robert A.; Broschat, Shira L.

2011-01-01

134

Graft rejection by cytolytic T cells. Specificity of the effector mechanism in the rejection of allogeneic marrow  

SciTech Connect

Cellular effector mechanisms of allograft rejection remain incompletely described. Characterizing the rejection of foreign-marrow allografts rather than solid-organ grafts has the advantage that the cellular composition of the marrow graft, as a single cell suspension, can be altered to include cellular components with differing antigen expression. Rejection of marrow grafts is sensitive to lethal doses of radiation in the mouse but resistant to sublethal levels of radiation. In an effort to identify cells mediating host resistance, lymphocytes were isolated and cloned from spleens of mice 7 days after sublethal TBI (650 cGy) and inoculation with allogeneic marrow. All clones isolated were cytolytic with specificity for MHC encoded gene products of the allogeneic marrow donor. When cloned cells were transferred in vivo into lethally irradiated (1025 cGy) recipients unable to reject allogeneic marrow, results utilizing splenic 125IUdR uptake indicated that these MHC-specific cytotoxic clones could suppress marrow proliferation. In order to characterize the effector mechanism and the ability of the clones to affect final engraftment, double donor chimeras were constructed so that 2 target cell populations differing at the MHC from each other and from the host were present in the same marrow allograft. Results directly demonstrated an ability of CTL of host MHC type to mediate graft rejection and characterized the effector mechanism as one with specificity for MHC gene products.

Nakamura, H.; Gress, R.E. (National Cancer Institute, Bethesda, MD (USA))

1990-02-01

135

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

136

Developmental control of integrin expression regulates Th2 effector homing  

Technology Transfer Automated Retrieval System (TEKTRAN)

Integrin CD18, a component of the LFA-1 complex that also includes CD11a, is essential for Th2, but not Th1, cell homing, but the explanation for this phenomenon remains obscure. In this study, we investigate the mechanism by which Th2 effector responses require the LFA-1 complex. CD11a-deficient T ...

137

p21-ras effector domain mutants constructed by \\  

Microsoft Academic Search

A series of mutations encoding single-amino-acid substitutions within the v-rasH effector domain were constructed, and the ability of the mutants to induce focal transformation of NIH 3T3 cells was studied. The mutations, which spanned codons 32 to 40, were made by a \\

J C Stone; W C Vass; B M Willumsen; D R Lowy

1988-01-01

138

Tumour escape: antitumour effectors too much of a good thing?  

Microsoft Academic Search

Although even “spontaneous” tumours are immunogenic and are commonly infiltrated by tumour antigen-specific T cells (at least in melanoma), most tumours are not completely rejected by the host, and cancer progresses. There is a growing realisation that many responses defined as antitumour effector mechanisms act as double-edged swords and under different conditions either become ineffective or even protumorigenic. Examples are

Graham Pawelec

2004-01-01

139

Genome-scale identification of Legionella pneumophila effectors using a machine learning approach.  

PubMed

A large number of highly pathogenic bacteria utilize secretion systems to translocate effector proteins into host cells. Using these effectors, the bacteria subvert host cell processes during infection. Legionella pneumophila translocates effectors via the Icm/Dot type-IV secretion system and to date, approximately 100 effectors have been identified by various experimental and computational techniques. Effector identification is a critical first step towards the understanding of the pathogenesis system in L. pneumophila as well as in other bacterial pathogens. Here, we formulate the task of effector identification as a classification problem: each L. pneumophila open reading frame (ORF) was classified as either effector or not. We computationally defined a set of features that best distinguish effectors from non-effectors. These features cover a wide range of characteristics including taxonomical dispersion, regulatory data, genomic organization, similarity to eukaryotic proteomes and more. Machine learning algorithms utilizing these features were then applied to classify all the ORFs within the L. pneumophila genome. Using this approach we were able to predict and experimentally validate 40 new effectors, reaching a success rate of above 90%. Increasing the number of validated effectors to around 140, we were able to gain novel insights into their characteristics. Effectors were found to have low G+C content, supporting the hypothesis that a large number of effectors originate via horizontal gene transfer, probably from their protozoan host. In addition, effectors were found to cluster in specific genomic regions. Finally, we were able to provide a novel description of the C-terminal translocation signal required for effector translocation by the Icm/Dot secretion system. To conclude, we have discovered 40 novel L. pneumophila effectors, predicted over a hundred additional highly probable effectors, and shown the applicability of machine learning algorithms for the identification and characterization of bacterial pathogenesis determinants. PMID:19593377

Burstein, David; Zusman, Tal; Degtyar, Elena; Viner, Ram; Segal, Gil; Pupko, Tal

2009-07-10

140

Diverse type VI secretion phospholipases are functionally plastic antibacterial effectors  

PubMed Central

Membranes allow the compartmentalization of biochemical processes and are therefore fundamental to life. The conservation of the cellular membrane, combined with its accessibility to secreted proteins, has made it a common target of factors mediating antagonistic interactions between diverse organisms. Here we report the discovery of a diverse superfamily of bacterial phospholipase enzymes. Within this superfamily, we defined enzymes with phospholipase A1 (PLA1) and A2 (PLA2) activity, which are common in host cell-targeting bacterial toxins and the venoms of certain insects and reptiles1,2. However, we find that the fundamental role of the superfamily is to mediate antagonistic bacterial interactions as effectors of the type VI secretion system (T6SS) translocation apparatus; accordingly, we name these proteins type VI lipase effectors (Tle). Our analyses indicate that PldA of Pseudomonas aeruginosa, a eukaryotic-like phospholipase D (PLD)3, is a member of the Tle superfamily and the founding substrate of the haemolysin co-regulated protein secretion island II T6SS (H2-T6SS). While prior studies have specifically implicated PldA and the H2-T6SS in pathogenesis3–5, we uncovered a specific role for the effector and its secretory machinery in intra- and inter-species bacterial interactions. Furthermore we find that this effector achieves its antibacterial activity by degrading phosphatidylethanolamine (PE), the major component of bacterial membranes. The surprising finding that virulence-associated phospholipases can serve as specific antibacterial effectors suggests that interbacterial interactions are a relevant factor driving the ongoing evolution of pathogenesis.

Russell, Alistair B.; LeRoux, Michele; Hathazi, Kristina; Agnello, Danielle M.; Ishikawa, Takahiko; Wiggins, Paul A.; Wai, Sun Nyunt; Mougous, Joseph D.

2013-01-01

141

The HrpN effector of Erwinia amylovora, which is involved in type III translocation, contributes directly or indirectly to callose elicitation on apple leaves.  

PubMed

Erwinia amylovora is responsible for fire blight of apple and pear trees. Its pathogenicity depends on a type III secretion system (T3SS) mediating the translocation of effectors into the plant cell. The DspA/E effector suppresses callose deposition on apple leaves. We found that E. amylovora and Pseudomonas syringae DC3000 tts mutants or peptide flg22 do not trigger callose deposition as strongly as the dspA/E mutant on apple leaves. This suggests that, on apple leaves, callose deposition is poorly elicited by pathogen-associated molecular patterns (PAMPs) such as flg22 or other PAMPs harbored by tts mutants and is mainly elicited by injected effectors or by the T3SS itself. Callose elicitation partly depends on HrpW because an hrpW-dspA/E mutant elicits lower callose deposition than a dspA/E mutant. Furthermore, an hrpN-dspA/E mutant does not trigger callose deposition, indicating that HrpN is required to trigger this plant defense reaction. We showed that HrpN plays a general role in the translocation process. Thus, the HrpN requirement for callose deposition may be explained by its role in translocation: HrpN could be involved in the translocation of other effectors inducing callose deposition. Furthermore, HrpN may also directly contribute to the elicitation process because we showed that purified HrpN induces callose deposition. PMID:21463207

Boureau, Tristan; Siamer, Sabrina; Perino, Claude; Gaubert, Stéphane; Patrit, Oriane; Degrave, Alexandre; Fagard, Mathilde; Chevreau, Elisabeth; Barny, Marie-Anne

2011-05-01

142

End-Effector Development for the PIP Puck Handling Robot  

SciTech Connect

It has been decided that excess, weapons-grade plutonium shall be immobilized to prevent nuclear proliferation. The method of immobilization is to encapsulate the plutonium in a ceramic puck, roughly the size of a hockey puck, using a sintering process. This method has been officially identified as the Plutonium Immobilization Process (PIP). A Can-in-Canister storage method will be used to further immobilize the plutonium. The Can-in-Canister method uses the existing design of a Defense Waste Processing Facility (DWPF) canister to house the plutonium pucks. the process begins with several pucks being stacked in a stainless steel can. Several of the stainless steel cans are stacked in a cage-like magazine. Several of the magazines are then placed in a DWPF canister. The DWPF canister is then filled with molten glass containing high-level, radioactive waste from the DWPF vitrification process. The Can-in-Canister method makes reclamation of plutonium from the pucks technically difficult and highly undesirable. The mechanical requirements of the Can-in-Canister process, in conjunction with the amount of time required to immobilize the vast quantities of weapons-grade plutonium, will expose personnel to unnecessarily high levels of radiation if the processes were completed manually, in glove boxes. Therefore, automated equipment is designed into the process to reduce or eliminate personnel exposure. Robots are used whenever the automated handling operations become complicated. There are two such operations in the initial stages of the Can-in-Canister process, which required a six-axis robot. The first operation is a press unloading process. The second operation is a tray transfer process. To successfully accomplish the operational tasks described in the two operations, the end-effector of the robot must be versatile, lightweight, and rugged. As a result of these demands, an extensive development process was undertaken to design the optimum end-effector for these puck-handling operations. As an overall requirement, it was desired to keep the design of the robot end-effector as simple as possible. There were pros and cons for either type of actuation method (pneumatic or electric). But, pneumatic actuation was chosen for its simplicity and durability in a radioactive environment. It was determined early in the design process that at least two different types of end-effectors would be required for each of the operations. Therefore, a tool changer was incorporated into the end-effector design. The tool changer would also provide for simple end-effector maintenance when used in the PIP process.

Fowley, M.D.

2001-01-03

143

End-Effector Development for the PIP Puck Handling Robot  

SciTech Connect

It has been decided that excess, weapons-grade plutonium shall be immobilized to prevent nuclear proliferation. The method of immobilization is to encapsulate the plutonium in a ceramic puck, roughly the size of a hockey puck, using a sintering process. This method has been officially identified as the Plutonium Immobilization Process (PIP). A Can-in-Canister storage method will be used to further immobilize the plutonium. The Can-in-Canister method uses the existing design of a Defense Waste Processing Facility (DWPF) canister to house the plutonium pucks. the process begins with several pucks being stacked in a stainless steel can. Several of the stainless steel cans are stacked in a cage-like magazine. Several of the magazines are then placed in a DWPF canister. The DWPF canister is then filled with molten glass containing high-level, radioactive waste from the DWPF vitrification process. The Can-in-Canister method makes reclamation of plutonium from the pucks technically difficult and highly undesirable. The mechanical requirements of the Can-in-Canister process, in conjunction with the amount of time required to immobilize the vast quantities of weapons-grade plutonium, will expose personnel to unnecessarily high levels of radiation if the processes were completed manually, in glove boxes. Therefore, automated equipment is designed into the process to reduce or eliminate personnel exposure. Robots are used whenever the automated handling operations become complicated. There are two such operations in the initial stages of the Can-in-Canister process, which required a six-axis robot. The first operation is a press unloading process. The second operation is a tray transfer process. To successfully accomplish the operational tasks described in the two operations, the end-effector of the robot must be versatile, lightweight, and rugged. As a result of these demands, an extensive development process was undertaken to design the optimum end-effector for these puck-handling operations. As an overall requirement, it was desired to keep the design of the robot end-effector as simple as possible. There were pros and cons for either type of actuation method (pneumatic or electric). But, pneumatic actuation was chosen for its simplicity and durability in a radioactive environment. It was determined early in the design process that at least two different types of end-effectors would be required for each of the operations. Therefore, a tool changer was incorporated into the end-effector design. The tool changer would also provide for simple end-effector maintenance when used in the PIP process.

Fowley, M.D.

2001-01-31

144

Powdery mildew fungal effector candidates share N-terminal Y/F/WxC-motif  

PubMed Central

Background Powdery mildew and rust fungi are widespread, serious pathogens that depend on developing haustoria in the living plant cells. Haustoria are separated from the host cytoplasm by a plant cell-derived extrahaustorial membrane. They secrete effector proteins, some of which are subsequently transferred across this membrane to the plant cell to suppress defense. Results In a cDNA library from barley epidermis containing powdery mildew haustoria, two-thirds of the sequenced ESTs were fungal and represented ~3,000 genes. Many of the most highly expressed genes encoded small proteins with N-terminal signal peptides. While these proteins are novel and poorly related, they do share a three-amino acid motif, which we named "Y/F/WxC", in the N-terminal of the mature proteins. The first amino acid of this motif is aromatic: tyrosine, phenylalanine or tryptophan, and the last is always cysteine. In total, we identified 107 such proteins, for which the ESTs represent 19% of the fungal clones in our library, suggesting fundamental roles in haustoria function. While overall sequence similarity between the powdery mildew Y/F/WxC-proteins is low, they do have a highly similar exon-intron structure, suggesting they have a common origin. Interestingly, searches of public fungal genome and EST databases revealed that haustoria-producing rust fungi also encode large numbers of novel, short proteins with signal peptides and the Y/F/WxC-motif. No significant numbers of such proteins were identified from genome and EST sequences from either fungi which do not produce haustoria or from haustoria-producing Oomycetes. Conclusion In total, we identified 107, 178 and 57 such Y/F/WxC-proteins from the barley powdery mildew, the wheat stem rust and the wheat leaf rust fungi, respectively. All together, our findings suggest the Y/F/WxC-proteins to be a new class of effectors from haustoria-producing pathogenic fungi.

2010-01-01

145

Tim-3 Pathway Controls Regulatory and Effector T cell Balance during HCV Infection  

PubMed Central

Hepatitis C virus (HCV) is remarkable at disrupting human immunity to establish chronic infection. Up-regulation of inhibitory signaling pathways (such as Tim-3) and accumulation of regulatory T cells (Tregs) play pivotal roles in suppressing antiviral effector T cell (Teff) responses that are essential for viral clearance. While the Tim-3 pathway has been shown to negatively regulate Teffs, its role in regulating Foxp3+ Tregs is poorly explored. In this pilot study, we investigated whether and how the Tim-3 pathway alters Foxp3+ Treg development and function in patients with chronic HCV infection. We found that Tim-3 was up-regulated, not only on IL-2-producing CD4+CD25+Foxp3? Teffs, but also on CD4+CD25+Foxp3+ Tregs, which accumulate in the peripheral blood of chronically HCV-infected individuals when compared to healthy subjects. Tim-3 expression on Foxp3+ Tregs positively correlated with expression of the proliferation marker Ki67 on Tregs, but inversely associated with proliferation of IL-2-producing Teffs. Moreover, Foxp3+ Tregs were found to be more resistant to, and Foxp3? Teffs more sensitive to, TCR-activation-induced cell apoptosis, which was reversible by blocking Tim-3 signaling. Consistent with its role in T cell proliferation and apoptosis, blockade of Tim-3 on CD4+CD25+ T cells promoted expansion of Teffs more substantially than Tregs through improving STAT-5 signaling, thus correcting the imbalance of Foxp3+ Tregs/Foxp3? Teffs that was induced by HCV infection. Taken together, the Tim-3 pathway appears to control regulatory and effector T cell balance through altering cell proliferation and apoptosis during HCV infection.

Moorman, Jonathan P.; Wang, Jia M.; Zhang, Ying; Ji, Xiao J.; Ma, Cheng J.; Wu, Xiao Y.; Jia, Zhan S.; Wang, Ke S.; Yao, Zhi Q.

2012-01-01

146

IR Background Suppression Studies.  

National Technical Information Service (NTIS)

A brief description of the background suppression scheme is described, and results obtained using the defocussing technique are presented. It has been demonstrated that a background suppression ratio of two orders of magnitudes can be obtained.

O. Shepherd W. P. Reidy T. F. Zehnpfennig G. A. Vanasse A. T. Stair

1977-01-01

147

Interleukin 35: A Key Mediator of Suppression and the Propagation of Infectious Tolerance  

PubMed Central

The importance of regulatory T cells (Tregs) in balancing the effector arm of the immune system is well documented, playing a central role in preventing autoimmunity, facilitating graft tolerance following organ transplantation, and having a detrimental impact on the development of anti-tumor immunity. These regulatory responses use a variety of mechanisms to mediate suppression, including soluble factors. While IL-10 and TGF-? are the most commonly studied immunosuppressive cytokines, the recently identified IL-35 has been shown to have potent suppressive function in vitro and in vivo. Furthermore, not only does IL-35 have the ability to directly suppress effector T cell responses, it is also able to expand regulatory responses by propagating infectious tolerance and generating a potent population of IL-35-expressing inducible Tregs. In this review, we summarize research characterizing the structure and function of IL-35, examine its role in disease, and discuss how it can contribute to the induction of a distinct population of inducible Tregs.

Olson, Brian M.; Sullivan, Jeremy A.; Burlingham, William J.

2013-01-01

148

Presensitizing with a Toll-like receptor 3 ligand impairs CD8 T-cell effector differentiation and IL-33 responsiveness  

PubMed Central

The synthetic double-stranded RNA poly(I:C) is commonly used as an adjuvant to boost CD8 T-cell function; however, polyinosinic:polycytidylic acid [poly(I:C)] can also suppress autoimmune disease. The mechanism by which a single adjuvant achieves two distinct immunoregulatory roles is unknown. Although it is clear that coadministration of poly(I:C) with antigen elicits strong adjuvant effects in mice, we found that poly(I:C) injection before antigen substantially reduced antigen-dependent CD8 T-cell responses. Notably, CD8 T cells sensitized in poly(I:C)-pretreated mice failed to fully up-regulate IL-33R (ST2), which led to impaired T-cell receptor-independent responses to IL-33. In contrast, nonsensitized effector CD8 T cells responded robustly to IL-33 using a two-signal cytokine mechanism. During an acute lung response to Staphylococcus aureus enterotoxin, peripheral injection of poly(I:C) manifested a suppressive process by inhibiting the differentiation of both antigen- and IL-33–responsive CD8 effectors systemically. These findings highlight that early exposure to double-stranded RNA reverses its role as an adjuvant and, importantly, prevents IL-33R up-regulation on CD8 effector T cells to dampen inflammation.

Ngoi, Soo Mun; St. Rose, Marie-Clare; Menoret, Antoine M.; Smith, Dirk E.; Tovey, Michael G.; Adler, Adam J.; Vella, Anthony T.

2012-01-01

149

Making Sense of Regulatory T Cell Suppressive Function  

PubMed Central

Several types of regulatory T cells maintain self-tolerance and control excessive immune responses to foreign antigens. The major regulatory T subsets described over the past decade and novel function in transplantation will be covered in this review with a focus on CD4+CD25+Foxp3+ regulatory T (Treg) cells. Multiple mechanisms have been proposed to explain how Treg cells inhibit effector cells but none can completely explain the observed effects in toto. Proposed mechanisms to explain suppressive activity of Treg cells include the generation of inhibitory cytokines, induced death of effector cells by cytokine deprivation or cytolysis, local metabolic perturbation of target cells mediated by changes in extracellular nucleotide/nucleoside fluxes with alterations in intracellular signaling molecules such as cyclic AMP, and finally inhibition of dendritic cell functions. A better understanding of how Treg cells operate at the molecular level could result in novel and safer therapeutic approaches in transplantation and immune-mediated diseases.

Shalev, Itay; Schmelzle, Moritz; Robson, Simon C.; Levy, Gary

2011-01-01

150

Posttranscriptional control of T cell effector function by aerobic glycolysis.  

PubMed

A "switch" from oxidative phosphorylation (OXPHOS) to aerobic glycolysis is a hallmark of T cell activation and is thought to be required to meet the metabolic demands of proliferation. However, why proliferating cells adopt this less efficient metabolism, especially in an oxygen-replete environment, remains incompletely understood. We show here that aerobic glycolysis is specifically required for effector function in T cells but that this pathway is not necessary for proliferation or survival. When activated T cells are provided with costimulation and growth factors but are blocked from engaging glycolysis, their ability to produce IFN-? is markedly compromised. This defect is translational and is regulated by the binding of the glycolysis enzyme GAPDH to AU-rich elements within the 3' UTR of IFN-? mRNA. GAPDH, by engaging/disengaging glycolysis and through fluctuations in its expression, controls effector cytokine production. Thus, aerobic glycolysis is a metabolically regulated signaling mechanism needed to control cellular function. PMID:23746840

Chang, Chih-Hao; Curtis, Jonathan D; Maggi, Leonard B; Faubert, Brandon; Villarino, Alejandro V; O'Sullivan, David; Huang, Stanley Ching-Cheng; van der Windt, Gerritje J W; Blagih, Julianna; Qiu, Jing; Weber, Jason D; Pearce, Edward J; Jones, Russell G; Pearce, Erika L

2013-06-01

151

Salmonella effector proteins and host-cell responses  

PubMed Central

Acute gastroenteritis caused by Salmonella enterica serovar typhimurium is a significant public health problem. This pathogen has very sophisticated molecular machinery encoded by the two pathogenicity islands, namely Salmonella Pathogenicity Island 1 and 2 (SPI-1 and SPI-2). Remarkably, both SPI-1 and SPI-2 are very tightly regulated in terms of timing of expression and spatial localization of the encoded effectors during the infection process within the host cell. This regulation is governed at several levels, including transcription and translation, and by post-translational modifications. In the context of a finely tuned regulatory system, we will highlight how these effector proteins co-opt host signaling pathways that control the ability of the organism to infect and survive within the host, as well as elicit host proinflammatory responses.

Srikanth, C.V.; Mercado-Lubo, Regino; Hallstrom, Kelly; McCormick, Beth A.

2013-01-01

152

Probing ras effector interactions on nanoparticle supported lipid bilayers.  

PubMed

Many biological processes take place in close proximity to lipid membranes. For a detailed understanding of the underlying mechanisms, tools are needed for the quantitative characterization of such biomolecular interactions. In this work, we describe the development of methods addressing the dynamics and affinities of protein complexes attached to an artificial membrane system. A semisynthetic approach provides the Ras protein with palmitoyl anchors, which allow stable membrane insertion, as a paradigm for membrane associated proteins that interact with multiple effectors. An artificial membrane system is constituted by nanoparticles covered with a lipid bilayer. Such a stable suspension allows for the characterization of the interaction between membrane-bound Ras and effector proteins using conventional fluorescence-based methods. PMID:18712896

Filchtinski, Daniel; Bee, Christine; Savopol, Tudor; Engelhard, Martin; Becker, Christian F W; Herrmann, Christian

2008-08-20

153

Human nonspecific suppressive lymphokines  

Microsoft Academic Search

Since the term “lymphokine” first appeared in print over 20 years ago, a tremendous number of these soluble mediators of the immune system have been described. Within the past few years, many human nonspecific suppressive lymphokines have been identified. This review discusses the historical basis of immunologic suppression and suppressor factors. Later reports describing suppressive human lymphokines are then grouped

Michael T. Halpern

1991-01-01

154

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.

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

2009-01-01

155

Apoptotic programs are determined during lineage commitment of CD4+ T effectors: selective regulation of T effector-memory apoptosis by inducible nitric oxide synthase.  

PubMed

Lineage-committed T effectors generated in response to Ag during the inflammatory phase are destined to die during termination of the immune response. We present evidence to suggest that molecular signatures of lineage commitment are reflected in apoptotic cascades activated in CD4(+) T effectors. Exemplifying this, ablation of inducible NO synthase (iNOS) protected effector-memory T (TEM) cells, but not T(Naive) or central-memory T cells, activated in vitro, from apoptosis triggered by cytokine deprivation. Furthermore, attrition of T effectors generated in the secondary, but not the primary, response to Ag was substantially reduced in mice, which received iNOS inhibitors. Distinct patterns of iNOS expression were revealed in wild-type TEM effectors undergoing apoptosis, and ablation of iNOS protein in primary and TEM wild-type effectors confirmed observations made in iNOS(-/-) cells. Describing molecular correlates of this dependence, mitochondrial damage, activation of the protein Bax, and release from mitochondria of the apoptosis-inducing factor were selectively abrogated in iNOS(-/-) TEM effectors. Suggesting that iNOS dependence was linked to the functional identity of T cell subsets, both iNOS induction and apoptosis were compromised in IFN-?(-/-) TEM effectors, which mirrored the response patterns of iNOS(-)(/)(-) TEM. Collectively, these observations suggest that programs regulating deletion and differentiation are closely integrated and likely encoded during lineage commitment of T effectors. PMID:23225886

Purushothaman, Divya; Marcel, Nimi; Garg, Megha; Venkataraman, Rasika; Sarin, Apurva

2012-12-05

156

CASPASE 2-MEDIATED TUMOR SUPPRESSION INVOLVES SURVIVIN GENE SILENCING  

PubMed Central

One of the pivotal functions of endogenous tumor suppression is to oppose aberrant cell survival, but the molecular requirements of this process are not completely understood. Here, we show that caspase 2, a death effector with largely unknown functions, represses transcription of the survivin gene, a general regulator of cell division and cytoprotection in tumors. This pathway involves caspase 2 proteolytic cleavage of the NF?B activator, RIP1. In turn, loss of RIP1 abolishes transcription of NF?B target genes, including survivin, resulting in deregulated mitotic transitions, enhanced apoptosis, and suppression of tumorigenicity, in vivo. Therefore, caspase 2 functions as an endogenous inhibitor of NF?B-dependent cell survival, and this mechanism may contribute to tumor suppression in humans.

Guha, Minakshi; Xia, Fang; Raskett, Christopher M.; Altieri, Dario C.

2009-01-01

157

Tumor Macrophage Redox and Effector Mechanisms Associated with Hypoxia  

PubMed Central

Monocytes are recruited from the circulation into solid tumors where they differentiate into macrophages with unique phenotypes. While macrophages utilize oxygen in a broad range of immune effector functions, the generation of reactive oxygen and nitrogen oxide species is less clear in the setting of hypoxia, which can be a prominent feature of solid tumors. The relationships between innate immunity, redox systems and the plasticity of phenotypic changes tumor-associated macrophages undergo in conjunction with tumor hypoxia will be examined.

Espey, Michael Graham

2006-01-01

158

A fly-by robotic tank inspection end effector  

Microsoft Academic Search

A robotic end effector has been developed that is capable of performing fly-by-fly, electromagnetic non-destructive evaluation (NDE) and visual inspection of the inside of the U.S. Department of Energy`s waste storage tanks. Furthermore, the system is also capable of sizing defects through its unique NDE technique, Alternating Current Field Measurement (ACFM). The NDE data is recorded and logged electronically and

M. M. Girtleman; B. Robertson; T. Gascor; B. Wightman; G. Hughes

1996-01-01

159

Double-effector nanoparticles: a synergistic approach to apoptotic hyperthermia.  

PubMed

Highly efficient apoptotic hyperthermia is achieved using a double-effector nanoparticle that can generate reactive oxygen species (ROS) and heat. ROS render cancer cells more susceptible to subsequent heat treatment, which remarkably increases the degree of apoptotic cell death. Xenograft tumors (100?mm(3)) in mice are completely eliminated within 8?days after a single mild magnetic hyperthermia treatment at 43?°C for 30?min. PMID:23139178

Yoo, Dongwon; Jeong, Heeyeong; Preihs, Christian; Choi, Jin-sil; Shin, Tae-Hyun; Sessler, Jonathan L; Cheon, Jinwoo

2012-11-08

160

Mesenchymal stem cell effects on T-cell effector pathways  

Microsoft Academic Search

Mesenchymal stem (stromal) cells (MSCs) are rare, multipotent progenitor cells that can be isolated and expanded from bone\\u000a marrow and other tissues. Strikingly, MSCs modulate the functions of immune cells, including T cells, B cells, natural killer\\u000a cells, monocyte\\/macrophages, dendritic cells, and neutrophils. T cells, activated to perform a range of different effector\\u000a functions, are the primary mediators of many

Michelle M Duffy; Thomas Ritter; Rhodri Ceredig; Matthew D Griffin

2011-01-01

161

The effector to memory transition of CD4 T cells  

Microsoft Academic Search

The small number of antigen-specific memory CD4 T cells surviving long-term after antigen or pathogen challenge are often\\u000a characterized by a surprising degree of phenotypic and functional heterogeneity. We here propose that the immune system has\\u000a evolved to express this diversity in memory T-cell populations, in order to provide flexibility in recall responses, via a\\u000a rapid transition from heterogeneous effector

K. Kai McKinstry; Tara M. Strutt; Susan L. Swain

2008-01-01

162

A transcription activator-like effector toolbox for genome engineering  

Microsoft Academic Search

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 modules that can be rearranged according to a simple cipher to target new DNA sequences. Customized TALEs can be used for a wide variety of genome engineering applications, including

Neville E Sanjana; Le Cong; Yang Zhou; Margaret M Cunniff; Guoping Feng; Feng Zhang

2012-01-01

163

The death effector domain protein family: regulators of cellular homeostasis  

Microsoft Academic Search

The death effector domain (DED) occurs in proteins that regulate programmed cell death. Both pro- and anti-apoptotic proteins containing DEDs have been identified. For Fas and possibly other death receptors, homotypic DED interactions connect the Fas-associated death domain (FADD) protein to caspase-8 and caspase-10 to mediate formation of the death-inducing signal complex. This complex can be inhibited by other DED-containing

Michael D. Tibbetts; Lixin Zheng; Michael J. Lenardo

2003-01-01

164

Inactivation of the apoptosis effector Apaf1 in malignant melanoma  

Microsoft Academic Search

Metastatic melanoma is a deadly cancer that fails to respond to conventional chemotherapy and is poorly understood at the molecular level. p53 mutations often occur in aggressive and chemoresistant cancers but are rarely observed in melanoma. Here we show that metastatic melanomas often lose Apaf-1, a cell-death effector that acts with cytochrome c and caspase-9 to mediate p53-dependent apoptosis. Loss

Jose L Pablos; P Capodieci; D Polsky; J Mora; M Esteller; X Opitz-Araya; R McCombie; JG Herman; WL Gerald; YA Lazebnik; C Cordon-Cardo; SW Lowe

2001-01-01

165

A nematode effector protein similar to annexins in host plants  

PubMed Central

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 75mM 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.

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

2010-01-01

166

TNFR2 Expression on CD25hiFOXP3+ T Cells Induced upon TCR Stimulation of CD4 T Cells Identifies Maximal Cytokine-Producing Effectors  

PubMed Central

In this study, we show that CD25hiTNFR2+ cells can be rapidly generated in vitro from circulating CD4 lymphocytes by polyclonal stimuli anti-CD3 in the presence of anti-CD28. The in vitro induced CD25hiTNFR2+ T cells express a conventional regulatory T cells phenotype FOXP3+CTLA4+CD127lo/?, but produce effector and immunoregulatory cytokines including IL-2, IL-10, and IFN-g. These induced CD25hiTNFR2+ T cells do not suppress target cell proliferation, but enhance it instead. Thus the CD25hiTNFR2+ phenotype induced rapidly following CD3/28 cross linking of CD4 T cells identifies cells with maximal proliferative and effector cytokine-producing capability. The in vivo counterpart of this cell population may play an important role in immune response initiation.

Govindaraj, Chindu; Scalzo-Inguanti, Karen; Scholzen, Anja; Li, Shuo; Plebanski, Magdalena

2013-01-01

167

A survey of the Pseudomonas syringae pv. tomato DC3000 type III secretion system effector repertoire reveals several effectors that are deleterious when expressed in Saccharomyces cerevisiae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The injection of nearly 30 effector proteins by the type III secretion system underlies the ability of Pseudomonas syringae pv. tomato strain DC3000 to cause disease in tomato and other host plants. The search for effector functions is complicated by redundancy within the repertoire and by plant R-g...

168

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.

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

2013-01-01

169

Herbivore exploits orally secreted bacteria to suppress plant defenses.  

PubMed

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

2013-09-09

170

The Capping Domain in RalF Regulates Effector Functions  

PubMed Central

The Legionella pneumophila effector protein RalF functions as a guanine nucleotide exchange factor (GEF) that activates the host small GTPase protein ADP-ribosylation factor (Arf), and recruits this host protein to the vacuoles in which this pathogen resides. GEF activity is conferred by the Sec7 domain located in the N-terminal region of RalF. Structural studies indicate that the C-terminal region of RalF makes contacts with residues in the Sec7 domain important for Arf interactions. Theoretically, the C-terminal region of RalF could prevent nucleotide exchange activity by blocking the ability of Arf to interact with the Sec7 domain. For this reason, the C-terminal region of RalF has been termed a capping domain. Here, the role of the RalF capping domain was investigated by comparing biochemical and effector activities mediated by this domain in both the Legionella RalF protein (LpRalF) and in a RalF ortholog isolated from the unrelated intracellular pathogen Rickettsia prowazekii (RpRalF). These data indicate that both RalF proteins contain a functional Sec7 domain and that the capping domain regulates RalF GEF activity. The capping domain has intrinsic determinants that mediate localization of the RalF protein inside of host cells and confer distinct effector activities. Localization mediated by the capping domain of LpRalF enables the GEF to modulate membrane transport in the secretory pathway, whereas, the capping domain of RpRalF enables this bacterial GEF to modulate actin dynamics occurring near the plasma membrane. Thus, these data reveal that divergence in the function of the C-terminal capping domain alters the in vivo functions of the RalF proteins.

Alix, Eric; Chesnel, Laurent; Bowzard, Brad J.; Tucker, Aimee M.; Delprato, Anna; Cherfils, Jacqueline; Wood, David O.; Kahn, Richard A.; Roy, Craig R.

2012-01-01

171

B-Cell-Delivered Gene Therapy Induces Functional T Regulatory Cells and Leads to a Loss of Antigen-Specific Effector Cells  

PubMed Central

Previous reports have shown that B-cell-mediated gene therapy can induce tolerance in several animal models for autoimmune diseases and inhibitory antibody formation in hemophilia A mice. We know from our previous work that the induction of tolerance following B-cell therapy is dependent upon CD25+ regulatory T cells (Tregs). To extend these studies and identify the effects of this gene therapy protocol on the target CD4 T cells, we have adapted in vitro suppression assays using Tregs isolated from treated and control mice. Using carboxyfluorescein succinimidyl ester (CFSE) dilution as a measure of T-cell responsiveness to FVIII, we show that CD25+ Tregs from treated mice are more suppressive than those from control animals. To monitor the induction of antigen-specific Tregs, we repeated these studies in ovalbumin (OVA) peptide-specific DO11.10 T-cell receptor (TCR) transgenic mice. Tregs from DO11.10 mice treated with a tolerogenic OVA–Ig construct are better than polyclonal Tregs at suppressing the proliferation of responder cells stimulated with OVA peptide 323–339 (pOVA). Furthermore, we show that following B-cell therapy, there is an increase in antigen-specific FoxP3+ Tregs, and there is also a distinct decrease in antigen-specific CD4+ effector T cells. These changes in the lymphocyte population shift the balance away from effector function toward a tolerogenic phenotype.

Skupsky, Jonathan; Zhang, Ai-Hong; Su, Yan; Scott, David W

2010-01-01

172

Estrogen-related receptor-? is a metabolic regulator of effector T-cell activation and differentiation  

PubMed Central

Stimulation of resting CD4+ T lymphocytes leads to rapid proliferation and differentiation into effector (Teff) or inducible regulatory (Treg) subsets with specific functions to promote or suppress immunity. Importantly, Teff and Treg use distinct metabolic programs to support subset specification, survival, and function. Here, we describe that the orphan nuclear receptor estrogen-related receptor-? (ERR?) regulates metabolic pathways critical for Teff. Resting CD4+ T cells expressed low levels of ERR? protein that increased on activation. ERR? deficiency reduced activated T-cell numbers in vivo and cytokine production in vitro but did not seem to modulate immunity through inhibition of activating signals or viability. Rather, ERR? broadly affected metabolic gene expression and glucose metabolism essential for Teff. In particular, up-regulation of Glut1 protein, glucose uptake, and mitochondrial processes were suppressed in activated ERR??/? T cells and T cells treated with two chemically independent ERR? inhibitors or by shRNAi. Acute ERR? inhibition also blocked T-cell growth and proliferation. This defect appeared as a result of inadequate glucose metabolism, because provision of lipids, but not increased glucose uptake or pyruvate, rescued ATP levels and cell division. Additionally, we have shown that Treg requires lipid oxidation, whereas Teff uses glucose metabolism, and lipid addition selectively restored Treg—but not Teff—generation after acute ERR? inhibition. Furthermore, in vivo inhibition of ERR? reduced T-cell proliferation and Teff generation in both immunization and experimental autoimmune encephalomyelitis models. Thus, ERR? is a selective transcriptional regulator of Teff metabolism that may provide a metabolic means to modulate immunity.

Michalek, Ryan D.; Gerriets, Valerie A.; Nichols, Amanda G.; Inoue, Makoto; Kazmin, Dmitri; Chang, Ching-Yi; Dwyer, Mary A.; Nelson, Erik R.; Pollizzi, Kristen N.; Ilkayeva, Olga; Giguere, Vincent; Zuercher, William J.; Powell, Jonathan D.; Shinohara, Mari L.; McDonnell, Donald P.; Rathmell, Jeffrey C.

2011-01-01

173

Deconstructing continuous flash suppression  

PubMed Central

In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular “Mondrian” CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

Yang, Eunice; Blake, Randolph

2012-01-01

174

Skin-Homing Receptors on Effector Leukocytes Are Differentially Sensitive to Glyco-Metabolic Antagonism in Allergic Contact Dermatitis1  

PubMed Central

T cell recruitment into inflamed skin is dependent on skin-homing receptor binding to endothelial (E)- and platelet (P)-selectin. These T cell receptors, or E- and P-selectin ligands, can be targeted by the metabolic fluorosugar inhibitor, 4-F-GlcNAc, to blunt cutaneous inflammation. Compelling new data indicate that, in addition to T cells, NK cells are also recruited to inflamed skin in allergic contact hypersensitivity (CHS) contingent on E- and P-selectin-binding. Using a model of allergic CHS, we evaluated the identity and impact of NK cell E-selectin ligand(s) on inflammatory responses and examined the oral efficacy of 4-F-GlcNAc. We demonstrated that the predominant E-selectin ligands on NK cells are P-selectin glycoprotein ligand-1 and protease-resistant glycolipids. We showed that, unlike the induced E-selectin ligand expression on activated T cells upon exposure to Ag, ligand expression on NK cells was constitutive. CHS responses were significantly lowered by orally administered 4-F-GlcNAc treatment. Although E-selectin ligand on activated T cells was suppressed, ligand expression on NK cells was insensitive to 4-F-GlcNAc treatment. These findings indicate that downregulating effector T cell E- and P-selectin ligand expression directly correlates with anti-inflammatory efficacy and provides new insight on metabolic discrepancies of E-selectin ligand biosynthesis in effector leukocytes in vivo.

Gainers, Madeliene E.; Descheny, Leyla; Barthel, Steven R.; Liu, Luzheng; Wurbel, Marc-Andre; Dimitroff, Charles J.

2010-01-01

175

Quetiapine, an Atypical Antipsychotic, Is Protective against Autoimmune-Mediated Demyelination by Inhibiting Effector T Cell Proliferation  

PubMed Central

Quetiapine (Que), a commonly used atypical antipsychotic drug (APD), can prevent myelin from breakdown without immune attack. Multiple sclerosisis (MS), an autoimmune reactive inflammation demyelinating disease, is triggered by activated myelin-specific T lymphocytes (T cells). In this study, we investigated the potential efficacy of Que as an immune-modulating therapeutic agent for experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. Que treatment was initiated on the onset of MOG35–55 peptide induced EAE mice and the efficacy of Que on modulating the immune response was determined by Flow Cytometry through analyzing CD4+/CD8+ populations and the proliferation of effector T cells (CD4+CD25?) in peripheral immune organs. Our results show that Que dramatically attenuates the severity of EAE symptoms. Que treatment decreases the extent of CD4+/CD8+ T cell infiltration into the spinal cord and suppresses local glial activation, thereby diminishing the loss of mature oligodendrocytes and myelin breakdown in the spinal cord of EAE mice. Our results further demonstrate that Que treatment decreases the CD4+/CD8+ T cell populations in lymph nodes and spleens of EAE mice and inhibits either MOG35–55 or anti-CD3 induced proliferation as well as IL-2 production of effector T cells (CD4+CD25?) isolated from EAE mice spleen. Together, these findings suggest that Que displays an immune-modulating role during the course of EAE, and thus may be a promising candidate for treatment of MS.

He, Yangtao; Wang, Linyun; Wang, Hongkai; Niu, Jianqin; Kong, Jiming; Li, Xinmin; Wu, Yuzhang; Xiao, Lan

2012-01-01

176

A fly-by robotic tank inspection end effector  

SciTech Connect

A robotic end effector has been developed that is capable of performing fly-by-fly, electromagnetic non-destructive evaluation (NDE) and visual inspection of the inside of the U.S. Department of Energy`s waste storage tanks. Furthermore, the system is also capable of sizing defects through its unique NDE technique, Alternating Current Field Measurement (ACFM). The NDE data is recorded and logged electronically and is tagged with position data from the deploying manipulator, allowing a complete mapping of the tank walls and future return to defect sites.

Girtleman, M.M.; Robertson, B.; Gascor, T.; Wightman, B. [Oceaneering Technologies, Houston, TX (United States); Hughes, G. [Oceaneering International, Aberdeen, (Scotland)

1996-12-31

177

Functionally Diverse MicroRNA Effector Complexes Are Regulated by Extracellular Signaling.  

PubMed

Because microRNAs (miRNAs) influence the expression of many genes in cells, discovering how the miRNA pathway is regulated is an important area of investigation. We found that the Drosophila miRNA-induced silencing complex (miRISC) exists in multiple forms. A constitutive form, called G-miRISC, is comprised of Ago1, miRNA, and GW182. Two distinct miRISC complexes that lack GW182 are regulated by mitogenic signaling. Exposure of cells to serum, lipids, or the tumor promoter PMA suppressed formation of these complexes. P-miRISC is comprised of Ago1, miRNA, and Loqs-PB, and it associates with mRNAs assembled into polysomes. The other regulated Ago1 complex associates with membranous organelles and is likely an intermediate in miRISC recycling. The formation of these complexes is correlated with a 5- to 10-fold stronger repression of target gene expression inside cells. Taken together, these results indicate that mitogenic signaling regulates the miRNA effector machinery to attenuate its repressive activities. PMID:24055343

Wu, Pei-Hsuan; Isaji, Mamiko; Carthew, Richard W

2013-09-19

178

CTLA4Ig inhibits effector T cells through regulatory T cells and TGF-?.  

PubMed

The CD28 costimulatory receptor is a critical regulator of T cell function, making it an attractive therapeutic target for the treatment of immune-mediated diseases. CTLA4Ig, now approved for use in humans, prevents naive T cell activation by binding to B7 proteins and blocking engagement of CD28. However, CTLA4Ig suppresses inflammation even if administered when disease is established, suggesting alternative mechanisms. We identified a novel, CD28-independent mechanism by which CTLA4Ig inhibits activated T cells. We show that in vitro, CTLA4Ig synergizes with NO from bone marrow-derived macrophages to inhibit T cell proliferation. Depletion of regulatory T cells (Tregs) or interference with TGF-? signaling abrogated the inhibitory effect of CTLA4Ig. Parallel in vivo experiments using an allergic airway inflammation model demonstrated that this novel mechanism required both macrophages and regulatory T cells. Furthermore, CTLA4Ig was ineffective in SMAD3-deficient mice, supporting a requirement for TGF-? signaling. Thus, in addition to preventing naive T cells from being fully activated, CTLA4Ig can turn off already activated effector T cells by an NO/regulatory T cell/TGF-?-dependent pathway. This mechanism is similar to cell-extrinsic effects of endogenous CTLA4 and may be particularly important in the ability of CTLA4Ig to treat chronic inflammatory disease. PMID:23956428

Deppong, Christine M; Bricker, Traci L; Rannals, Brandy D; Van Rooijen, Nico; Hsieh, Chyi-Song; Green, Jonathan M

2013-08-16

179

Modulation of Treg cells/T effector function by GITR signaling is context-dependent.  

PubMed

Treg cells express high levels of the glucocorticoid-induced tumor necrosis factor-related receptor (GITR), while resting conventional T (Tconv) cells express low levels that are increased upon activation. Manipulation of GITR/GITR-Ligand (GITR-L) interactions results in enhancement of immune responses, but it remains unclear whether this enhancement is secondary to costimulation of Tconv cells or to reversal of Treg-cell-mediated suppression. Here, we used a nondepleting Fc-GITR-L and combinations of WT and GITR KO Treg cells and Tconv cells to reexamine the effects of GITR stimulation on each subpopulation in both unmanipulated mice and mice with inflammatory bowel disease. Treatment of mice with Fc-GITR-L resulted in significant expansion of Treg cells and a modest expansion of Tconv cells. When RAG KO mice were reconstituted with Tconv cells alone, GITR-L resulted in Tconv-cell expansion and severe inflammatory bowel disease. The protective effect of Treg cells was lost in the presence of Fc-GITR-L, secondary to death of the Treg cells. When RAG KO mice were reconstituted with Treg cells alone, the transferred cells expanded normally, and Fc-GITR-L treatment resulted in a loss of Foxp3 expression, but the ex-Treg cells did not cause any pathology. The effects of GITR activation are complex and depend on the host environment and the activation state of the Treg cells and T effector cells. PMID:23722868

Ephrem, Amal; Epstein, Alan L; Stephens, Geoffrey L; Thornton, Angela M; Glass, Deborah; Shevach, Ethan M

2013-07-03

180

RAN GTPase is an effector of the invasive/metastatic phenotype induced by osteopontin.  

PubMed

Osteopontin (OPN) is a phosphorylated glycoprotein that binds to alpha v-containing integrins and is important in malignant transformation and cancer. Previously, we have utilized suppressive subtractive hybridization between mRNAs isolated from the Rama 37 (R37) rat mammary cell line and a subclone rendered invasive and metastatic by stable transfection with an expression vector for OPN to identify RAN GTPase (RAN) as the most overexpressed gene, in addition to that of OPN. Here we show that transfection of noninvasive R37 cells with an expression vector for RAN resulted in increased anchorage-independent growth, cell attachment and invasion through Matrigel in vitro, and metastasis in syngeneic rats. This induction of a malignant phenotype was induced independently of the expression of OPN, and was reversed by specifically reducing the expression of RAN using small-interfering RNAs. By using a combination of mutant protein and inhibitors, it was found that RAN signal transduction occurred through the c-Met receptor and PI3 kinase. This study therefore identifies RAN as a novel effector of OPN-mediated malignant transformation and some of its downstream signaling events in a mammary epithelial model of cancer invasion/metastasis. PMID:18794800

Kurisetty, V V; Johnston, P G; Johnston, N; Erwin, P; Crowe, P; Fernig, D G; Campbell, F C; Anderson, I P; Rudland, P S; El-Tanani, M K

2008-09-15

181

Investigation of a bio-inspired lift-enhancing effector on a 2D airfoil.  

PubMed

A flap mounted on the upper surface of an airfoil, called a 'lift-enhancing effector', has been shown in wind tunnel tests to have a similar function to a bird's covert feathers, which rise off the wing's surface in response to separated flows. The effector, fabricated from a thin Mylar sheet, is allowed to rotate freely about its leading edge. The tests were performed in the NCSU subsonic wind tunnel at a chord Reynolds number of 4 × 10(5). The maximum lift coefficient with the effector was the same as that for the clean airfoil, but was maintained over an angle-of-attack range from 12° to almost 20°, resulting in a very gentle stall behavior. To better understand the aerodynamics and to estimate the deployment angle of the free-moving effector, fixed-angle effectors fabricated out of stiff wood were also tested. A progressive increase in the stall angle of attack with increasing effector angle was observed, with diminishing returns beyond the effector angle of 60°. Drag tests on both the free-moving and fixed effectors showed a marked improvement in drag at high angles of attack. Oil flow visualization on the airfoil with and without the fixed-angle effectors proved that the effector causes the separation point to move aft on the airfoil, as compared to the clean airfoil. This is thought to be the main mechanism by which an effector improves both lift and drag. A comparison of the fixed-effector results with those from the free-effector tests shows that the free effector's deployment angle is between 30° and 45°. When operating at and beyond the clean airfoil's stall angle, the free effector automatically deploys to progressively higher angles with increasing angles of attack. This slows down the rapid upstream movement of the separation point and avoids the severe reduction in the lift coefficient and an increase in the drag coefficient that are seen on the clean airfoil at the onset of stall. Thus, the effector postpones the stall by 4-8° and makes the stall behavior more gentle. The benefits of using the effector could include care-free operations at high angles of attack during perching and maneuvering flight, especially in gusty conditions. PMID:22498691

Johnston, Joe; Gopalarathnam, Ashok

2012-04-12

182

Listeriolysin O derived from Listeria monocytogenes inhibits the effector phase of an experimental allergic rhinitis induced by ovalbumin in mice.  

PubMed

Listeriolysin O (LLO) derived from Listeria monocytogenes is highly capable of inducing interleukin (IL)-12, IL-18 and interferon (IFN)-gamma, and facilitates the generation of Th1 cells. We have recently shown that recombinant LLO (rLLO) inhibits generation of ovalbumin (OVA)-specific Th2 immune response by skewing maturation of antigen-specific T cells into Th1 cells. In the present study, we investigated the effect of rLLO on the effector phase of Th2-dependent allergic rhinitis in BALB/c mice sensitized with OVA. In mice sensitized intraperitoneally and challenged intranasally with OVA, nasal allergic symptoms such as sneezing and nose-scratching were observed at a high frequency. A high titre of anti-OVA IgE antibody was detected in sera and a large number of eosinophils migrated into the nasal tissue. However, rLLO treatment during the intranasal challenge inhibited the allergic symptoms, production of anti-OVA IgE antibody and eosinophil infiltration. Though rLLO did not affect antigen-specific cytokine production from splenic CD4(+) T cells, rLLO significantly suppressed OVA-specific IL-4 and IL-5 production from nasal mononuclear cells. We further found that rLLO inhibited the recruitment of CD4(+) T cells in nasal mucosa, and diminished the transcription and cell surface expression of CCR4 on splenic CD4(+) T cells. Moreover, rLLO was able to inhibit the passive cutaneous anaphylaxis reaction mediated by anaphylactic antibodies (IgE and IgG(1)) and mast cells. Taken together, these data showed that rLLO suppresses the effector phase of allergic rhinitis by inhibition of Th2 cell recruitment to nasal mucosa and type I allergic reaction. PMID:16734617

Yamamoto, K; Kawamura, I; Tominaga, T; Nomura, T; Ito, J; Mitsuyama, M

2006-06-01

183

Cell type-specific effects of Yersinia pseudotuberculosis virulence effectors.  

PubMed

One important feature of Yersinia pseudotuberculosis that enables resistance against the host immune defence is delivery of the antiphagocytic effectors YopH and YopE into phagocytic cells. The tyrosine phosphatase YopH influences integrin signalling, and YopE impairs cytoskeletal dynamics by inactivating Rho GTPases. Here, we report the impact of these effectors on internalization by dendritic cells (DCs), which internalize antigens to orchestrate host immune responses. We found that this pathogen resists internalization by DCs via YopE. YopH that is important for blocking phagocytosis by macrophages and neutrophils and which is also present inside the DCs does not contribute to the resistance. However, the YopH targets Fyb and p130Cas show higher expression levels in macrophages than in DCs. Furthermore, live cell microscopy revealed that the cells internalize Y. pseudotuberculosis in different ways: the macrophages utilize a locally restricted receptor-mediated zipper mechanism, whereas DCs utilize macropinocytosis involving constitutive ruffling that randomly catches bacteria into membrane folds. We conclude that YopH impacts early phagocytic signalling from the integrin receptor to which the bacterium binds and that this tight receptor-mediated stimulation is absent in DC macropinocytosis. Inactivation of cytoskeletal dynamics by YopE affects ruffling activity and hence also internalization. The different modes of internalization can be coupled to the major functions of these respective cell types: elimination by phagocytosis and antigen sampling. PMID:19681909

Fahlgren, Anna; Westermark, Linda; Akopyan, Karen; Fällman, Maria

2009-08-04

184

Pointing hand stimuli induce spatial compatibility effects and effector priming.  

PubMed

The present study investigated the automatic influence of perceiving a picture that indicates other's action on one's own task performance in terms of spatial compatibility and effector priming. Participants pressed left and right buttons with their left and right hands respectively, depending on the color of a central dot target. Preceding the target, a left or right hand stimulus (pointing either to the left or right with the index or little finger) was presented. In Experiment 1, with brief presentation of the pointing hand, a spatial compatibility effect was observed: responses were faster when the direction of the pointed finger and the response position were spatially congruent than when incongruent. The spatial compatibility effect was larger for the pointing index finger stimulus compared to the pointing little finger stimulus. Experiment 2 employed longer duration of the pointing hand stimuli. In addition to the spatial compatibility effect for the pointing index finger, the effector priming effect was observed: responses were faster when the anatomical left/right identity of the pointing and response hands matched than when the pointing and response hands differed in left/right identity. The results indicate that with sufficient processing time, both spatial/symbolic and anatomical features of a static body part implying another's action simultaneously influence different aspects of the perceiver's own action. Hierarchical coding, according to which an anatomical code is used only when a spatial code is unavailable, may not be applicable if stimuli as well as responses contain anatomical features. PMID:23637688

Nishimura, Akio; Michimata, Chikashi

2013-04-26

185

Multiplicity of effectors of the cardioprotective agent, diazoxide.  

PubMed

Diazoxide has been identified over the past 50years to have a number of physiological effects, including lowering the blood pressure and rectifying hypoglycemia. Today it is used clinically to treat these conditions. More recently, another important mode of action emerged: diazoxide has powerful protective properties against cardiac ischemia. The heart has intrinsic protective mechanisms against ischemia injury; one of which is ischemic preconditioning. Diazoxide mimics ischemic preconditioning. The purpose of this treatise is to review the literature in an attempt to identify the many effectors of diazoxide and discuss how they may contribute to diazoxide's cardioprotective properties. Particular emphasis is placed on the concentration ranges in which diazoxide affects its different targets and how this compares with the concentrations commonly used to study cardioprotection. It is concluded that diazoxide may have several potential effectors that may potentially contribute to cardioprotection, including KATP channels in the pancreas, smooth muscle, endothelium, neurons and the mitochondrial inner membrane. Diazoxide may also affect other ion channels and ATPases and may directly regulate mitochondrial energetics. It is possible that the success of diazoxide lies in this promiscuity and that the compound acts to rebalance multiple physiological processes during cardiac ischemia. PMID:23792087

Coetzee, William A

2013-06-19

186

Mast cell-derived mediators promote murine neutrophil effector functions.  

PubMed

Mast cells are able to trigger life-saving immune responses in murine models for acute inflammation. In such settings, several lines of evidence indicate that the rapid and protective recruitment of neutrophils initiated by the release of mast cell-derived pro-inflammatory mediators is a key element of innate immunity. Herein, we investigate the impact of mast cells on critical parameters of neutrophil effector function. In the presence of activated murine bone marrow-derived mast cells, neutrophils freshly isolated from bone marrow rapidly lose expression of CD62L and up-regulate CD11b, the latter being partly driven by mast cell-derived TNF and GM-CSF. Mast cells also strongly enhance neutrophil phagocytosis and generation of reactive oxygen species. All these phenomena partly depend on mast cell-derived TNF and to a greater extend on GM-CSF. Furthermore, spontaneous apoptosis of neutrophils is greatly diminished due to the ability of mast cells to deliver antiapoptotic GM-CSF. Finally, we show in a murine model for acute lung inflammation that neutrophil phagocytosis is impaired in mast cell-deficient Kit (W-sh) /Kit (W-sh) mice but can be restored upon mast cell engraftment. Thus, a previously underrated feature of mast cells is their ability to boost neutrophil effector functions in immune responses. PMID:23728776

Doener, Fatma; Michel, Anastasija; Reuter, Sebastian; Friedrich, Pamela; Böhm, Livia; Relle, Manfred; Codarri, Laura; Tenzer, Stefan; Klein, Matthias; Bopp, Tobias; Schmitt, Edgar; Schild, Hansjörg; Radsak, Markus Philipp; Taube, Christian; Stassen, Michael; Becker, Marc

2013-06-01

187

Innovative technology summary report: Confined sluicing end effector  

SciTech Connect

A Confined Sluicing End-Effector (CSEE) was field tested during the summer of 1997 in Tank W-3, one of the Gunite and Associated Tanks (GAAT) at the Oak Ridge Reservation (ORR). It should be noted that the specific device used at the Oak Ridge Reservation demonstration was the Sludge Retrieval End-Effector (SREE), although in common usage it is referred to as the CSEE. Deployed by the Modified Light-Duty Utility Arm (MLDUA) and the Houdini remotely operated vehicle (ROV), the CSEE was used to mobilize and retrieve waste from the tank. After removing the waste, the CSEE was used to scarify the gunite walls of Tank W-3, removing approximately 0.1 in of material. The CSEE uses three rotating water-jets to direct a short-range pressurized jet of water to effectively mobilize the waste. Simultaneously, the water and dislodged tank waste, or scarified materials, are aspirated using a water-jet pump-driven conveyance system. The material is then pumped outside of the tank, where it can be stored for treatment. The technology, its performance, uses, cost, and regulatory issues are discussed.

NONE

1998-09-01

188

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

SciTech Connect

This gripper 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

189

Vision feedback based end-effector motion control of a flexible robot arm  

Microsoft Academic Search

This paper addresses issue of end-effector trajectory tracking control of robot arms with link flexibility. By using a vision system consisting of a CCD camera and a video tracker, a direct method of end-effector position sensing and an indirect method for link deflection sensing are presented. Based on vision feedback using the vision system, an end-effector trajectory tracking control strategy

Zhao-hui Jiang; Tsuyoshi Eguchi

2007-01-01

190

Computational Predictions Provide Insights into the Biology of TAL Effector Target Sites  

PubMed Central

Transcription activator-like (TAL) effectors are injected into host plant cells by Xanthomonas bacteria to function as transcriptional activators for the benefit of the pathogen. The DNA binding domain of TAL effectors is composed of conserved amino acid repeat structures containing repeat-variable diresidues (RVDs) that determine DNA binding specificity. In this paper, we present TALgetter, a new approach for predicting TAL effector target sites based on a statistical model. In contrast to previous approaches, the parameters of TALgetter are estimated from training data computationally. We demonstrate that TALgetter successfully predicts known TAL effector target sites and often yields a greater number of predictions that are consistent with up-regulation in gene expression microarrays than an existing approach, Target Finder of the TALE-NT suite. We study the binding specificities estimated by TALgetter and approve that different RVDs are differently important for transcriptional activation. In subsequent studies, the predictions of TALgetter indicate a previously unreported positional preference of TAL effector target sites relative to the transcription start site. In addition, several TAL effectors are predicted to bind to the TATA-box, which might constitute one general mode of transcriptional activation by TAL effectors. Scrutinizing the predicted target sites of TALgetter, we propose several novel TAL effector virulence targets in rice and sweet orange. TAL-mediated induction of the candidates is supported by gene expression microarrays. Validity of these targets is also supported by functional analogy to known TAL effector targets, by an over-representation of TAL effector targets with similar function, or by a biological function related to pathogen infection. Hence, these predicted TAL effector virulence targets are promising candidates for studying the virulence function of TAL effectors. TALgetter is implemented as part of the open-source Java library Jstacs, and is freely available as a web-application and a command line program.

Grau, Jan; Wolf, Annett; Reschke, Maik; Bonas, Ulla; Posch, Stefan; Boch, Jens

2013-01-01

191

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

192

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.

Rivas, Susana; Genin, Stephane

2011-01-01

193

Isolation and Characterization of Effector-Loop Mutants of CDC42 in Yeast  

PubMed Central

The highly conserved small GTPase Cdc42p is a key regulator of cell polarity and cytoskeletal organization in eukaryotic cells. Multiple effectors of Cdc42p have been identified, although it is unclear how their activities are coordinated to produce particular cell behaviors. One strategy used to address the contributions made by different effector pathways downstream of small GTPases has been the use of “effector-loop” mutants of the GTPase that selectively impair only a subset of effector pathways. We now report the generation and preliminary characterization of a set of effector-loop mutants of Saccharomyces cerevisiae CDC42. These mutants define genetically separable pathways influencing actin or septin organization. We have characterized the phenotypic defects of these mutants and the binding defects of the encoded proteins to known yeast Cdc42p effectors in vitro. The results suggest that these effectors cannot account for the observed phenotypes, and therefore that unknown effectors exist that affect both actin and septin organization. The availability of partial function alleles of CDC42 in a genetically tractable system serves as a useful starting point for genetic approaches to identify such novel effectors.

Gladfelter, Amy S.; Moskow, John J.; Zyla, Trevin R.; Lew, Daniel J.

2001-01-01

194

Regulation of Cell Wall-Bound Invertase in Pepper Leaves by Xanthomonas campestris pv. vesicatoria Type Three Effectors  

PubMed Central

Xanthomonas campestris pv. vesicatoria (Xcv) possess a type 3 secretion system (T3SS) to deliver effector proteins into its Solanaceous host plants. These proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. There is increasing evidence that hexoses contribute to defense responses. They act as substrates for metabolic processes and as metabolic semaphores to regulate gene expression. Especially an increase in the apoplastic hexose-to-sucrose ratio has been suggested to strengthen plant defense. This shift is brought about by the activity of cell wall-bound invertase (cw-Inv). We examined the possibility that Xcv may employ type 3 effector (T3E) proteins to suppress cw-Inv activity during infection. Indeed, pepper leaves infected with a T3SS-deficient Xcv strain showed a higher level of cw-Inv mRNA and enzyme activity relative to Xcv wild type infected leaves. Higher cw-Inv activity was paralleled by an increase in hexoses and mRNA abundance for the pathogenesis-related gene PRQ. These results suggest that Xcv suppresses cw-Inv activity in a T3SS-dependent manner, most likely to prevent sugar-mediated defense signals. To identify Xcv T3Es that regulate cw-Inv activity, a screen was performed with eighteen Xcv strains, each deficient in an individual T3E. Seven Xcv T3E deletion strains caused a significant change in cw-Inv activity compared to Xcv wild type. Among them, Xcv lacking the xopB gene (Xcv ?xopB) caused the most prominent increase in cw-Inv activity. Deletion of xopB increased the mRNA abundance of PRQ in Xcv ?xopB-infected pepper leaves, but not of Pti5 and Acre31, two PAMP-triggered immunity markers. Inducible expression of XopB in transgenic tobacco inhibited Xcv-mediated induction of cw-Inv activity observed in wild type plants and resulted in severe developmental phenotypes. Together, these data suggest that XopB interferes with cw-Inv activity in planta to suppress sugar-enhanced defense responses during Xcv infection.

Sonnewald, Sophia; Priller, Johannes P. R.; Schuster, Julia; Glickmann, Eric; Hajirezaei, Mohammed-Reza; Siebig, Stefan; Mudgett, Mary Beth; Sonnewald, Uwe

2012-01-01

195

Interleukin 4 inhibits TGF-?-induced-Foxp3+T cells and generates, in combination with TGF-?, Foxp3? effector T cells that produce interleukins 9 and 10  

PubMed Central

Foxp3 is a key transcription factor involved in the generation and function of regulatory T (Treg) cells. Transforming growth factor ? (TGF-?) induces Foxp3, which generates inducible Foxp3+ Treg cells from naïve T cells, and interleukin 6 (IL-6) inhibits the generation of inducible Treg cells and induces T helper cells that produce IL-17 (TH-17 cells). However, a role for IL-4 in the generation of TGF-?-induced Treg cells and/or the generation of effector CD4+ T helper cells has not been studied. Here, we show that IL-4 blocked the generation of TGF-?-induced Foxp3+ Treg cells. Instead, IL-4 induced a population of T helper cells that predominantly produce IL-9 and IL-10. The IL-9+IL-10+ T cells did not exhibit any regulatory properties in spite of producing large quantities of IL-10. Adoptive transfer of IL-9+IL-10+producing T cells into RAG-1-deficient mice induced colitis and peripheral neuritis. Interestingly, the severity of tissue inflammation was aggravated when IL-9+IL-10+ T cells were co-transferred with CD45RBhi CD4+ effector T cells into RAG-1-deficient mice, which indicated that IL-9+IL-10+ T cells do not display any suppressive function and therefore constitute a unique population of IL-10-producing helper-effector T cells that promote tissue inflammation.

Dardalhon, Valerie; Awasthi, Amit; Kwon, Hyoung; Galileos, George; Gao, Wenda; Sobel, Raymond A.; Mitsdoerffer, Meike; Strom, Terry B.; Elyaman, Wassim; Ho, I-Cheng; Khoury, Samia; Oukka, Mohamed; Kuchroo, Vijay K

2010-01-01

196

A diametric role for OX40 in the response of effector/memory CD4+ T cells and regulatory T cells to alloantigen.  

PubMed

OX40 is a member of the TNFR superfamily that has potent costimulatory properties. Although the impact of blockade of the OX40-OX40 ligand (OX40L) pathway has been well documented in models of autoimmune disease, its effect on the rejection of allografts is less well defined. In this article, we show that the alloantigen-mediated activation of naive and memory CD4(+) T cells results in the induction of OX40 expression and that blockade of OX40-OX40L interactions prevents skin allograft rejection mediated by either subset of T cells. Moreover, a blocking anti-OX40 had no effect on the activation and proliferation of T cells; rather, effector T cells failed to accumulate in peripheral lymph nodes and subsequently migrate to skin allografts. This was found to be the result of an enhanced degree of cell death among proliferating effector cells. In clear contrast, blockade of OX40-OX40L interactions at the time of exposure to alloantigen enhanced the ability of regulatory T cells to suppress T cell responses to alloantigen by supporting, rather than diminishing, regulatory T cell survival. These data show that OX40-OX40L signaling contributes to the evolution of the adaptive immune response to an allograft via the differential control of alloreactive effector and regulatory T cell survival. Moreover, these data serve to further highlight OX40 and OX40L as therapeutic targets to assist the induction of tolerance to allografts and self-Ags. PMID:23817421

Kinnear, Gillian; Wood, Kathryn J; Fallah-Arani, Farnaz; Jones, Nick D

2013-07-01

197

Distinct Effects of IL-18 on the Engraftment and Function of Human Effector CD8+ T Cells and Regulatory T Cells  

PubMed Central

IL-18 has pleotropic effects on the activation of T cells during antigen presentation. We investigated the effects of human IL-18 on the engraftment and function of human T cell subsets in xenograft mouse models. IL-18 enhanced the engraftment of human CD8+ effector T cells and promoted the development of xenogeneic graft versus host disease (GVHD). In marked contrast, IL-18 had reciprocal effects on the engraftment of CD4+CD25+Foxp3+ regulatory T cells (Tregs) in the xenografted mice. Adoptive transfer experiments indicated that IL-18 prevented the suppressive effects of Tregs on the development of xenogeneic GVHD. The IL-18 results were robust as they were observed in two different mouse strains. In addition, the effects of IL-18 were systemic as IL-18 promoted engraftment and persistence of human effector T cells and decreased Tregs in peripheral blood, peritoneal cavity, spleen and liver. In vitro experiments indicated that the expression of the IL-18R? was induced on both CD4 and CD8 effector T cells and Tregs, and that the duration of expression was less sustained on Tregs. These preclinical data suggest that human IL-18 may have use as an adjuvant for immune reconstitution after cytotoxic therapies, and to augment adoptive immunotherapy, donor leukocyte infusions, and vaccine strategies.

Danet-Desnoyers, Gwenn; Liu, Ronghua; Jiang, Shuguang; Albelda, Steven M.; Golovina, Tatiana; Coukos, George; Riley, James L.; Jonak, Zdenka L.; June, Carl H.

2008-01-01

198

Suppressive oligodeoxynucleotides promote the development of Th17 cells.  

PubMed

Synthetic oligonucleotides containing repetitive TTAGGG motifs mimic the immunosuppressive activity of telomeric DNA. These suppressive oligonucleotides (Sup ODN) are effective in the treatment/prevention of various inflammatory and autoimmune diseases in mice. The therapeutic activity of Sup ODN was originally attributed to the inhibition of Th1 cell activation. Current results indicate that Sup ODN also promote the maturation of naive CD4(+) T cells into Th17 effectors. The generation of Th17 cells is linked to the prolonged activation of signal transducer and activator of transcription (STAT)3 mediated by suppressor of cytokine signaling 3 (SOCS3) inhibition. In vivo studies show that treatment with Sup ODN promotes Th17 responsiveness under physiological conditions, increasing host resistance to Candida albicans infection. These findings support the development of Sup ODN to suppress pathological inflammatory conditions and improve host resistance to fungal pathogens. PMID:23844143

Bode, Christian; Yang, Xiang-Ping; Kiu, Hiu; Klinman, Dennis M

2013-07-02

199

Suppressive Oligodeoxynucleotides Promote the Development of Th17 Cells  

PubMed Central

Synthetic oligonucleotides containing repetitive TTAGGG motifs mimic the immunosuppressive activity of telomeric DNA. These suppressive oligonucleotides (Sup ODN) are effective in the treatment/prevention of various inflammatory and autoimmune diseases in mice. The therapeutic activity of Sup ODN was originally attributed to the inhibition of Th1 cell activation. Current results indicate that Sup ODN also promote the maturation of naive CD4+ T cells into Th17 effectors. The generation of Th17 cells is linked to the prolonged activation of signal transducer and activator of transcription (STAT)3 mediated by suppressor of cytokine signaling 3 (SOCS3) inhibition. In vivo studies show that treatment with Sup ODN promotes Th17 responsiveness under physiological conditions, increasing host resistance to Candida albicans infection. These findings support the development of Sup ODN to suppress pathological inflammatory conditions and improve host resistance to fungal pathogens.

Bode, Christian; Yang, Xiang-Ping; Kiu, Hiu; Klinman, Dennis M.

2013-01-01

200

Regulatory T Cell Suppressive Potency Dictates the Balance between Bacterial Proliferation and Clearance during Persistent Salmonella Infection  

PubMed Central

The pathogenesis of persistent infection is dictated by the balance between opposing immune activation and suppression signals. Herein, virulent Salmonella was used to explore the role and potential importance of Foxp3-expressing regulatory T cells in dictating the natural progression of persistent bacterial infection. Two distinct phases of persistent Salmonella infection are identified. In the first 3–4 weeks after infection, progressively increasing bacterial burden was associated with delayed effector T cell activation. Reciprocally, at later time points after infection, reductions in bacterial burden were associated with robust effector T cell activation. Using Foxp3GFP reporter mice for ex vivo isolation of regulatory T cells, we demonstrate that the dichotomy in infection tempo between early and late time points is directly paralleled by drastic changes in Foxp3+ Treg suppressive potency. In complementary experiments using Foxp3DTR mice, the significance of these shifts in Treg suppressive potency on infection outcome was verified by enumerating the relative impacts of regulatory T cell ablation on bacterial burden and effector T cell activation at early and late time points during persistent Salmonella infection. Moreover, Treg expression of CTLA-4 directly paralleled changes in suppressive potency, and the relative effects of Treg ablation could be largely recapitulated by CTLA-4 in vivo blockade. Together, these results demonstrate that dynamic regulation of Treg suppressive potency dictates the course of persistent bacterial infection.

Johanns, Tanner M.; Ertelt, James M.; Rowe, Jared H.; Way, Sing Sing

2010-01-01

201

Induction and suppression of PEN3 focal accumulation during Pseudomonas syringae pv. tomato DC3000 infection of Arabidopsis.  

PubMed

The pleiotropic drug resistance (PDR) proteins belong to the super-family of ATP-binding cassette (ABC) transporters. AtPDR8, also called PEN3, is required for penetration resistance of Arabidopsis to nonadapted powdery mildew fungi. During fungal infection, plasma-membrane-localized PEN3 is concentrated at fungal entry sites, as part of the plant's focal immune response. Here, we show that the pen3 mutant is compromised in resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000. P. syringae pv. tomato DC3000 infection or treatment with a flagellin-derived peptide, flg22, induced strong focal accumulation of PEN3-green fluorescent protein. Interestingly, after an initial induction of PEN3 accumulation, P. syringae pv. tomato DC3000 but not the type-III-secretion-deficient mutant hrcC could suppress PEN3 accumulation. Moreover, transgenic overexpression of the P. syringae pv. tomato DC3000 effector AvrPto was sufficient to suppress PEN3 focal accumulation in response to flg22. Analyses of P. syringae pv. tomato DC3000 effector deletion mutants showed that individual effectors, including AvrPto, appear to be insufficient to suppress PEN3 accumulation when delivered by bacteria, suggesting a requirement for a combined action of multiple effectors. Collectively, our results indicate that PEN3 plays a positive role in plant resistance to a bacterial pathogen and show that focal accumulation of PEN3 protein may be a useful cellular response marker for the Arabidopsis-P. syringae interaction. PMID:23815470

Xin, Xiu-Fang; Nomura, Kinya; Underwood, William; He, Sheng Yang

2013-08-01

202

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

203

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.

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

2013-01-01

204

[Transcription activator-like effectors(TALEs)based genome engineering].  

PubMed

Systematic reverse-engineering of functional genome architecture requires precise modifications of gene sequences and transcription levels. The development and application of transcription activator-like effectors(TALEs) has created a wealth of genome engineering possibilities. TALEs are a class of naturally occurring DNA-binding proteins found in the plant pathogen Xanthomonas species. The DNA-binding domain of each TALE typically consists of tandem 34-amino acid repeat modules rearranged according to a simple cipher to target new DNA sequences. Customized TALEs can be used for a wide variety of genome engineering applications, including transcriptional modulation and genome editing. Such "genome engineering" has now been established in human cells and a number of model organisms, thus opening the door to better understanding gene function in model organisms, improving traits in crop plants and treating human genetic disorders. PMID:24115666

Zhao, Mei-Wei; Duan, Cheng-Li; Liu, Jiang

2013-10-01

205

Thrombin A-Chain: Activation Remnant or Allosteric Effector?  

PubMed Central

Although prothrombin is one of the most widely studied enzymes in biology, the role of the thrombin A-chain has been neglected in comparison to the other domains. This paper summarizes the current data on the prothrombin catalytic domain A-chain region and the subsequent thrombin A-chain. Attention is given to biochemical characterization of naturally occurring prothrombin A-chain mutations and alanine scanning mutants in this region. While originally considered to be simply an activation remnant with little physiologic function, the thrombin A-chain is now thought to play a role as an allosteric effector in enzymatic reactions and may also be a structural scaffold to stabilize the protease domain.

Carter, Isis S. R.; Vanden Hoek, Amanda L.; Pryzdial, Edward L. G.; MacGillivray, Ross T. A.

2010-01-01

206

The versatile Legionella effector protein DrrA.  

PubMed

The human pathogen Legionella pneumophila is a bacterium that infects human cells and interferes with intracellular signaling. The Legionella protein DrrA is one of the numerous effectors that the bacterium translocates into the host cytosol. DrrA binds to the Legionella containing vacuole (LCV), an organelle in which Legionella survives and replicates, and recruits and activates the vesicular trafficking regulator Rab1 to redirect vesicular trafficking between the endoplasmatic reticulum and the Golgi. After depositing Rab1 at the LCV, DrrA covalently modifies Rab1 with an AMP moiety at a specific tyrosine residue (Tyr77), which is centrally located in the functionally important switch II region. This adenylylation reaction interferes with the deactivation of Rab1 by GTPase activating proteins (GAPs), thereby presumably prolonging the active state of the protein at the LCV. Here, we summarize the versatile properties of DrrA and speculate on the effects of Rab1-adenylylation. PMID:21509184

Goody, Roger S; Müller, Matthias P; Schoebel, Stefan; Oesterlin, Lena K; Blümer, Julia; Peters, Heide; Blankenfeldt, Wulf; Itzen, Aymelt

2011-01-01

207

SGT1b is required for HopZ3-mediated suppression of the epiphytic growth of Pseudomonas syringae on N. benthamiana  

PubMed Central

Type III secreted effectors shape the potential of bacterial pathogens to cause disease on plants. Some effectors affect pathogen growth only in specific niches. For example, HopZ3 causes reduced epiphytic growth of Pseudomonas syringae strain B728a on Nicotiana benthamiana. This raises the question of whether genes important for effector-triggered disease resistance are needed for responses to effectors whose major effect is in the epiphytic niche. We report that SGT1b, a protein known to be important for defense activation, is essential for HopZ3-mediated suppression of PsyB728a epiphytic growth. SGT1b is required for HopZ3- and AvrB3-induced cell death in N. benthamiana plants that express the Pto resistance gene from tomato. We suggest that HopZ3 activates R gene mediated responses in N. benthamiana.

Lee, Jiyoung; Teitzel, Gail M.; Greenberg, Jean T.

2012-01-01

208

The Structural Basis of Rho Effector Recognition Revealed by the Crystal Structure of Human RhoA Complexed with the Effector Domain of PKN\\/PRK1  

Microsoft Academic Search

The small G protein Rho has emerged as a key regulator of cellular events involving cytoskeletal reorganization. Here we report the 2.2 Å crystal structure of RhoA bound to an effector domain of protein kinase PKN\\/PRK1. The structure reveals the antiparallel coiled-coil finger (ACC finger) fold of the effector domain that binds to the Rho specificity-determining regions containing switch I,

Ryoko Maesaki; Kentaro Ihara; Toshiyuki Shimizu; Shinya Kuroda; Kozo Kaibuchi; Toshio Hakoshima

1999-01-01

209

Suppression Workshop Summary.  

National Technical Information Service (NTIS)

A workshop on the Chemical Suppression of Rocket Afterburning and of Gun Muzzle Flash was held at the Ballistic Research Laboratory on 11 and 12 June 1986. It brought together scientists representing six countries to share their collective fundamental und...

J. M. Heimerl

1987-01-01

210

Parasitic Suppressing Circuit.  

National Technical Information Service (NTIS)

A circuit for suppressing parasitic oscillations across an inductor operating in a resonant mode is described. The circuit includes a switch means and resistive means connected serially across the inductor. A unidirectional resistive-capacitive network is...

F. L. Raposa J. T. Fowler

1972-01-01

211

Parasitic Suppressing Circuit.  

National Technical Information Service (NTIS)

A circuit for suppressing parasitic oscillations across an inductor operating in a resonant mode is described. The circuit includes a switch means and resistive means connected serially across the inductor. A unidirectional resistive-capacitive network is...

J. T. Fowler F. L. Raposa

1973-01-01

212

Interleukin 10 and transforming growth factor ? contribute to the development of experimentally induced allergic conjunctivitis in mice during the effector phase  

PubMed Central

Aim To investigate the involvement of interleukin (IL)10 and transforming growth factor (TGF) ? in the development of experimentally induced allergic conjunctivitis in mice. Methods Balb/c mice were actively sensitised with ragweed in alum, and then challenged with ragweed in eye drops after 10?days. 24?h later, the conjunctivas, spleens and blood were collected for histological and cytokine expression analyses, proliferation and cytokine production assays and measurement of immunoglobulin (Ig) levels. Mice developing experimentally induced allergic conjunctivitis were injected intraperitoneally with 200??g of anti?IL10 or anti?TGF ? antibodies at 0, 2, 4, 6 and 8?days (induction phase treatment) or 500??g of antibodies 2?h before ragweed challenge (effector phase treatment). Normal rat IgG was used for control injections. Results Treatment with either anti?IL10 or anti?TGF ? antibodies during the induction phase did not affect eosinophil infiltration into the conjunctiva. By contrast, treatment with either antibody during the effector phase suppressed infiltration. During the effector phase, treatment with anti?TGF ? antibody, but not the anti?IL10 antibody, markedly up regulated proliferation and Th2 cytokine production by splenocytes. IL1? levels in the conjunctiva were reduced after treatment with either antibody; in addition, eotaxin and tumour necrosis factor ? levels were reduced after treatment with antibody to TGF ?. Conclusions IL10 and TGF ? do not have immunosuppressive roles in the development of experimentally induced allergic conjunctivitis. Rather, they augment the infiltration of eosinophils into the conjunctiva during the effector phase of experimentally induced allergic conjunctivitis.

Fukushima, A; Sumi, T; Fukuda, K; Kumagai, N; Nishida, T; Yagita, H; Ueno, H

2006-01-01

213

PD1 Inhibits Antiviral Immunity at the Effector Phase in the Liver  

Microsoft Academic Search

Unlike naive T cells, effector T cells can be activated by either T cell receptor signal or costim- ulatory signal alone and therefore the absence of costimulatory molecules on tissue cells cannot explain the tolerance mechanism at the effector phase. Here we report that PD-L1, the ligand for the immunoinhibitory receptor PD-1, was expressed on vascular endothelium in peripheral tissues.

Yoshiko Iwai; Seigo Terawaki; Masaya Ikegawa; Taku Okazaki; Tasuku Honjo

2003-01-01

214

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

215

Two-dimensional analysis of human lymphocyte proteins: I. An assay for lymphocyte effectors  

Microsoft Academic Search

We describe an assay for lymphocyte effectors that is capable of establishing the existence of regulators of lymphocyte gene expression (including post-transcriptional control and protein processing) and has the ability to characterize the response at the molecular level. The hypothesis that circulating effector substances excreted through the kidney can be actively present in human urine was tested with this assay.

K. E. Willard; N. G. Anderson

1981-01-01

216

Investigation of a bio-inspired lift-enhancing effector on a 2D airfoil  

Microsoft Academic Search

A flap mounted on the upper surface of an airfoil, called a ‘lift-enhancing effector’, has been shown in wind tunnel tests to have a similar function to a bird's covert feathers, which rise off the wing's surface in response to separated flows. The effector, fabricated from a thin Mylar sheet, is allowed to rotate freely about its leading edge. The

Joe Johnston; Ashok Gopalarathnam

2012-01-01

217

Evaluation of effector cell fate and function by in vivo bioluminescence imaging  

Microsoft Academic Search

The effector functions of immune cells have typically been examined using assays that require sampling of tissues or cells to reveal specific aspects of an immune response (e.g., antigen-specificity, cytokine expression or killing of target cells). The outcome of an immune response in vivo, however, is not solely determined by a single effector function of a specific cell population, but

Matthias Edinger; Petra Hoffmann; Christopher H Contag; Robert S Negrin

2003-01-01

218

Prevalence and polymorphism of genes encoding translocated effector proteins among clinical isolates of Salmonella enterica  

Microsoft Academic Search

Pathogenic Salmonella enterica strains are capable of causing local and\\/or systemic infections. They employ two type III secretion systems to translocate an array of virulence-associated proteins (effector proteins) directly into the cytosol of target cells of the host. Earlier data had shown that changes in the repertoire of translocated effector proteins may contribute to the adaptation of Salmonella strains to

Rita Prager; Susanne Mirold; Erhard Tietze; Ute Strutz; Barbara Knüppel; Wolfgang Rabsch; Wolf-Dieter Hardt; Helmut Tschäpe

2000-01-01

219

Functionalized Nano-Robot End Effector for in situ Sensing and Manipulation of Biological Specimen  

Microsoft Academic Search

Atomic force microscopy is a powerful and widely used imaging technique that can visualize single molecules both in air and solution. Using the AFM tip as the end effector, it can be modified into a nano-robot which can manipulate objects in nanoscale. By functionalizing the nano-robot end effector with antibodies, atomic force microscopy is able to identify specific types of

Guangyong Li; Ning Xi; Donna H. Wang

2005-01-01

220

Bacterial EPIYA effectors - Where do they come from? What are they? Where are they going?  

PubMed Central

Recent studies have revealed a distinct class of bacterial effectors defined by the presence of EPIYA or EPIYA-related motif. These bacterial EPIYA effectors are delivered into host cells via type III or IV secretion, where they undergo tyrosine phosphorylation at the EPIYA motif and thereby manipulate host signalling by promiscuously interacting with multiple SH2 domain-containing proteins. Up to now, nine EPIYA effectors have been identified from various bacteria. These effectors do not share sequence homology outside the EPIYA motif, arguing against the idea that they have common ancestors. A search of mammalian proteomes revealed the presence of a mammalian EPIYA-containing protein, Pragmin, which potentiates Src family kinase (SFK) activity by binding and sequestrating the SFK inhibitor Csk upon EPIYA phosphorylation. As several bacterial EPIYA effectors also target Csk, they may have evolved through generation of sequences that mimic the Pragmin EPIYA motif. EPIYA motifs are often diverged through multiple duplications in each bacterial effector. Such a structural plasticity appears to be due to intrinsic disorder of the EPIYA-containing region, which enables the bacterial effectors to undergo efficient phosphorylation and mediate promiscuous interaction with multiple host proteins. Given the functional versatility of the EPIYA motif, many more bacterial EPIYA effectors will soon be emerging.

Hayashi, Takeru; Morohashi, Hiroko; Hatakeyama, Masanori

2013-01-01

221

TAL effectors: highly adaptable phytobacterial virulence factors and readily engineered DNA-targeting proteins.  

PubMed

Transcription activator-like (TAL) effectors are transcription factors injected into plant cells by pathogenic bacteria of the genus Xanthomonas. They function as virulence factors by activating host genes important for disease, or as avirulence factors by turning on genes that provide resistance. DNA-binding specificity is encoded by polymorphic repeats in each protein that correspond one-to-one with different nucleotides. This code has facilitated target identification and opened new avenues for engineering disease resistance. It has also enabled TAL effector customization for targeted gene control, genome editing, and other applications. This article reviews the structural basis for TAL effector-DNA specificity, the impact of the TAL effector-DNA code on plant pathology and engineered resistance, and recent accomplishments and future challenges in TAL effector-based DNA targeting. PMID:23707478

Doyle, Erin L; Stoddard, Barry L; Voytas, Daniel F; Bogdanove, Adam J

2013-05-23

222

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.

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

223

Antigen-specific effector CD4 T lymphocytes school lamina propria dendritic cells to transfer innate tolerance.  

PubMed

Dendritic cells (DCs) have been shown to play a major role in oral tolerance, and this function has been associated with their ability to produce anti-inflammatory cytokines and to induce suppressive regulatory T cells. In this study, we demonstrate that upon oral administration of Ag, lamina propia (LP) DCs engage specific T cells and acquire a novel mechanism by which they transfer tolerance against diverse T cell specificities. Indeed, when Ig-myelin oligodendrocyte glycoprotein (MOG) carrying the MOG(35-55) epitope was orally administered into either T cell-sufficient or -deficient mice, only the T cell-sufficient hosts yielded CD8?(+) and CD8?(-) LP DCs that were able to transfer tolerance to a variety of MHC class II-restricted effector T cells. Surprisingly, these LP DCs upregulated programmed cell death ligand 1 during the initial interaction with MOG-specific T cells and used this inhibitory molecule to suppress activation of T cells regardless of Ag specificity. Furthermore, oral Ig-MOG was able to overcome experimental autoimmune encephalomyelitis induced with CNS homogenate, indicating that the DCs are able to modulate disease involving diverse T cell specificities. This previously unrecognized attribute potentiates DCs against autoimmunity. PMID:23686493

Cascio, Jason A; Haymaker, Cara L; Divekar, Rohit D; Zaghouani, Sarah; Khairallah, Marie-Therese; Wan, Xiaoxiao; Rowland, Linda M; Dhakal, Mermagya; Chen, Weirong; Zaghouani, Habib

2013-05-17

224

TIM-4 Has Dual Function in the Induction and Effector Phases of Murine Arthritis.  

PubMed

T cell Ig and mucin domain (TIM)-4 is involved in immune regulation. However, the pathological function of TIM-4 has not been understood and remains to be clarified in various disease models. In this study, DBA/1 mice were treated with anti-TIM-4 mAb during the induction or effector phase of collagen-induced arthritis (CIA). Anti-TIM-4 treatment in the induction phase exacerbated the development of CIA. In vitro experiments suggest that CD4 T cells bind to TIM-4 on APCs, which induces inhibitory effect to CD4 T cells. In contrast, therapeutic treatment with anti-TIM-4 mAb just before or after the onset or even at later stage of CIA significantly suppressed the development and progression by reducing proinflammatory cytokines in the ankle joints without affecting T or B cell responses. Consistently, clinical arthritis scores of collagen Ab-induced arthritis, which is not mediated by T or B cells, were significantly reduced in anti-TIM-4-treated mice with a concomitant decrease of proinflammatory cytokines in the joints. In vitro, macrophages secreted proinflammatory cytokines in response to TIM-4-Ig protein and LPS, which were reduced by the anti-TIM-4 mAb. The anti-TIM-4 mAb also inhibited the differentiation and bone-resorbing activity of osteoclasts. These results indicate that TIM-4 has two distinct functions depending on the stage of arthritis. The therapeutic effect of anti-TIM-4 mAb on arthritis is mediated by the inhibition of proinflammatory cytokine production by inflammatory cells, osteoclast differentiation, and bone resorption, suggesting that TIM-4 might be an appropriate target for the therapeutic treatment of arthritis. PMID:24068667

Abe, Yoshiyuki; Kamachi, Fumitaka; Kawamoto, Toshio; Makino, Fumihiko; Ito, Jun; Kojima, Yuko; Moustapha, Alaa El Din Hussein; Usui, Yoshihiko; Yagita, Hideo; Takasaki, Yoshinari; Okumura, Ko; Akiba, Hisaya

2013-09-25

225

Comparative analysis of the XopD T3S effector family in plant pathogenic bacteria  

PubMed Central

SUMMARY XopD is a type III effector protein that is required for Xanthomonas campestris pathovar vesicatoria (Xcv) growth in tomato. It is a modular protein consisting of an N-terminal DNA-binding domain, two EAR transcriptional repressor motifs, and a C-terminal SUMO protease. In tomato, XopD functions as a transcriptional repressor, resulting in the suppression of defense responses at late stages of infection. A survey of available genome sequences for phytopathogenic bacteria revealed that XopD homologs are limited to species within three Genera of Proteobacteria – Xanthomonas, Acidovorax, and Pseudomonas. While the EAR motif(s) and SUMO protease domain are conserved in all the XopD-like proteins, variation exists in the length and sequence identity of the N-terminal domains. Comparative analysis of the DNA sequences surrounding xopD and xopD-like genes led to revised annotation of the xopD gene. Edman degradation sequence analysis and functional complementation studies confirmed that the xopD gene from Xcv encodes a 760 amino acid protein with a longer N-terminal domain than previously predicted. None of the XopD-like proteins studied complemented Xcv ?xopD mutant phenotypes in tomato leaves suggesting that the N-terminus of XopD defines functional specificity. Xcv ?xopD strains expressing chimeric fusion proteins containing the N-terminus of XopD fused to the EAR motif(s) and SUMO protease domain of the XopD-like protein from Xanthomonas campestris pathovar campestris strain B100 were fully virulent in tomato demonstrating that the N-terminus of XopD controls specificity in tomato.

Kim, Jung-Gun; Taylor, Kyle W.; Mudgett, Mary Beth

2011-01-01

226

Lysophosphatidylcholine as an effector of fatty acid-induced insulin resistance[S  

PubMed Central

The mechanism of FFA-induced insulin resistance is not fully understood. We have searched for effector molecules(s) in FFA-induced insulin resistance. Palmitic acid (PA) but not oleic acid (OA) induced insulin resistance in L6 myotubes through C-Jun N-terminal kinase (JNK) and insulin receptor substrate 1 (IRS-1) Ser307 phosphorylation. Inhibitors of ceramide synthesis did not block insulin resistance by PA. However, inhibition of the conversion of PA to lysophosphatidylcholine (LPC) by calcium-independent phospholipase A2 (iPLA2) inhibitors, such as bromoenol lactone (BEL) or palmitoyl trifluoromethyl ketone (PACOCF3), prevented insulin resistance by PA. iPLA2 inhibitors or iPLA2 small interfering RNA (siRNA) attenuated JNK or IRS-1 Ser307 phosphorylation by PA. PA treatment increased LPC content, which was reversed by iPLA2 inhibitors or iPLA2 siRNA. The intracellular DAG level was increased by iPLA2 inhibitors, despite ameliorated insulin resistance. Pertussis toxin (PTX), which inhibits LPC action through the G-protein coupled receptor (GPCR)/G?i, reversed insulin resistance by PA. BEL administration ameliorated insulin resistance and diabetes in db/db mice. JNK and IRS-1Ser307 phosphorylation in the liver and muscle of db/db mice was attenuated by BEL. LPC content was increased in the liver and muscle of db/db mice, which was suppressed by BEL. These findings implicate LPC as an important lipid intermediate that links saturated fatty acids to insulin resistance.

Han, Myoung Sook; Lim, Yu-Mi; Quan, Wenying; Kim, Jung Ran; Chung, Kun Wook; Kang, Mira; Kim, Sunshin; Park, Sun Young; Han, Joong-Soo; Park, Shin-Young; Cheon, Hyae Gyeong; Dal Rhee, Sang; Park, Tae-Sik; Lee, Myung-Shik

2011-01-01

227

Tim-3-Expressing CD4+ and CD8+ T Cells in Human Tuberculosis (TB) Exhibit Polarized Effector Memory Phenotypes and Stronger Anti-TB Effector Functions  

PubMed Central

T-cell immune responses modulated by T-cell immunoglobulin and mucin domain-containing molecule 3 (Tim-3) during Mycobacterium tuberculosis (Mtb) infection in humans remain poorly understood. Here, we found that active TB patients exhibited increases in numbers of Tim-3-expressing CD4+ and CD8+ T cells, which preferentially displayed polarized effector memory phenotypes. Consistent with effector phenotypes, Tim-3+CD4+ and Tim-3+CD8+ T-cell subsets showed greater effector functions for producing Th1/Th22 cytokines and CTL effector molecules than Tim-3? counterparts, and Tim-3-expressing T cells more apparently limited intracellular Mtb replication in macrophages. The increased effector functions for Tim-3-expressing T cells consisted with cellular activation signaling as Tim-3+CD4+ and Tim-3+CD8+ T-cell subsets expressed much higher levels of phosphorylated signaling molecules p38, stat3, stat5, and Erk1/2 than Tim-3- controls. Mechanistic experiments showed that siRNA silencing of Tim-3 or soluble Tim-3 treatment interfering with membrane Tim-3-ligand interaction reduced de novo production of IFN-? and TNF-? by Tim-3-expressing T cells. Furthermore, stimulation of Tim-3 signaling pathways by antibody cross-linking of membrane Tim-3 augmented effector function of IFN-? production by CD4+ and CD8+ T cells, suggesting that Tim-3 signaling helped to drive stronger effector functions in active TB patients. This study therefore uncovered a previously unknown mechanism for T-cell immune responses regulated by Tim-3, and findings may have implications for potential immune intervention in TB.

Liao, Hongying; Zhang, Yan; Wang, Hua; Li, Shaoyuan; Luo, Yanfen; Fang, Danyun; Li, Guobao; Zhou, Boping; Shen, Ling; Chen, Crystal Y.; Huang, Dan; Cai, Jiye; Cao, Kaiyuan; Jiang, Lifang; Zeng, Gucheng; Chen, Zheng W.

2012-01-01

228

Suppression of developmental anomalies by maternal macrophages in mice  

PubMed Central

We tested whether nonspecific tumoricidal immune cells can suppress congenital malformations by killing precursor cells destined to cause such defects. Pretreatment of pregnant ICR mice with synthetic (Pyran copolymer) and biological (Bacillus Calmette-Guerin) agents significantly suppressed radiation- and chemical-induced congenital malformations (cleft palate, digit anomalies, tail anomalies, etc.). Such suppressive effects were associated with the activation of maternal macrophages by these agents, but were lost either after the disruption of activated macrophages by supersonic waves or by inhibition of their lysosomal enzyme activity with trypan blue. These results indicate that a live activated macrophage with active lysosomal enzymes can be an effector cell to suppress maldevelopment. A similar reduction by activated macrophages was observed in strain CL/Fr, which has a high spontaneous frequency of cleft lips and palates. Furthermore, Pyran-activated maternal macrophages could pass through the placenta, and enhanced urethane-induced cell killing (but not somatic mutation) in the embryo. It is likely that a maternal immunosurveillance system eliminating preteratogenic cells allows for the replacement with normal totipotent blast cells during the pregnancy to protect abnormal development.

1990-01-01

229

Deregulation of Rab and Rab Effector Genes in Bladder Cancer  

PubMed Central

Growing evidence indicates that Rab GTPases, key regulators of intracellular transport in eukaryotic cells, play an important role in cancer. We analysed the deregulation at the transcriptional level of the genes encoding Rab proteins and Rab-interacting proteins in bladder cancer pathogenesis, distinguishing between the two main progression pathways so far identified in bladder cancer: the Ta pathway characterized by a high frequency of FGFR3 mutation and the carcinoma in situ pathway where no or infrequent FGFR3 mutations have been identified. A systematic literature search identified 61 genes encoding Rab proteins and 223 genes encoding Rab-interacting proteins. Transcriptomic data were obtained for normal urothelium samples and for two independent bladder cancer data sets corresponding to 152 and 75 tumors. Gene deregulation was analysed with the SAM (significant analysis of microarray) test or the binomial test. Overall, 30 genes were down-regulated, and 13 were up-regulated in the tumor samples. Five of these deregulated genes (LEPRE1, MICAL2, RAB23, STXBP1, SYTL1) were specifically deregulated in FGFR3-non-mutated muscle-invasive tumors. No gene encoding a Rab or Rab-interacting protein was found to be specifically deregulated in FGFR3-mutated tumors. Cluster analysis showed that the RAB27 gene cluster (comprising the genes encoding RAB27 and its interacting partners) was deregulated and that this deregulation was associated with both pathways of bladder cancer pathogenesis. Finally, we found that the expression of KIF20A and ZWINT was associated with that of proliferation markers and that the expression of MLPH, MYO5B, RAB11A, RAB11FIP1, RAB20 and SYTL2 was associated with that of urothelial cell differentiation markers. This systematic analysis of Rab and Rab effector gene deregulation in bladder cancer, taking relevant tumor subgroups into account, provides insight into the possible roles of Rab proteins and their effectors in bladder cancer pathogenesis. This approach is applicable to other group of genes and types of cancer.

Ho, Joel R.; Chapeaublanc, Elodie; Kirkwood, Lisa; Nicolle, Remy; Benhamou, Simone; Lebret, Thierry; Allory, Yves; Southgate, Jennifer; Radvanyi, Francois; Goud, Bruno

2012-01-01

230

Intact B7-H3 signaling promotes allograft prolongation through preferential suppression of Th1 effector responses.  

PubMed

Ligands of the B7 family provide both positive and negative costimulatory signals to the CD28 family of receptors on T lymphocytes, the balance of which determines the immune response. B7-H3 is a member of the B7 family whose function in T-cell activation has been the subject of some controversy: in autoimmunity and tumor immunity, it has been described as both costimulatory and coinhibitory, while in transplantation, B7-H3 signaling is thought to contribute to graft rejection. However, we now demonstrate results to the contrary. Signaling through a putative B7-H3 receptor prolonged allograft survival in a fully MHC-mismatched cardiac model and promoted a shift toward a Th2 milieu; conversely, B7-H3 blockade, achieved by use of a blocking antibody, resulted in accelerated rejection, an effect associated with enhanced IFN-? production. Finally, graft prolongation achieved by CTLA4 Ig was shortened both by B7-H3 blockade and the absence of recipient B7-H3. These findings suggest a coinhibitory role for B7-H3. However, experience with other CD28/B7 family members suggests that immune redundancy plays a crucial role in determining the functions of various pathways. Given the abundance of conflicting data, it is plausible that, under differing conditions, B7-H3 may have both positive and negative costimulatory functions. PMID:22733595

Ueno, Takuya; Yeung, Melissa Y; McGrath, Martina; Yang, Sunmi; Zaman, Nadia; Snawder, Benjamin; Padera, Robert F; Magee, Ciara N; Gorbatov, Rostic; Hashiguchi, Masaaki; Azuma, Miyuki; Freeman, Gordon J; Sayegh, Mohamed H; Najafian, Nader

2012-09-01

231

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

232

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

Microsoft Academic Search

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

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

2009-01-01

233

Transfer of the Salmonella type III effector sopE between unrelated phage families 1 1 Edited by M. Gottesman  

Microsoft Academic Search

Salmonella spp. are pathogenic enterobacteria that employ type III secretion systems to translocate effector proteins and modulate responses of host cells. The repertoire of translocated effector proteins is thought to define host specificity and epidemic virulence, and varies even between closely related Salmonella strains. Therefore, horizontal transfer of effector protein genes between Salmonella strains plays a key role in shaping

Susanne Mirold; Wolfgang Rabsch; Helmut Tschäpe; Wolf-Dietrich Hardt

2001-01-01

234

Salmonella Type III Effector AvrA Stabilizes Cell Tight Junctions to Inhibit Inflammation in Intestinal Epithelial Cells  

Microsoft Academic Search

Salmonella Typhimurium is a major cause of human gastroenteritis. The Salmonella type III secretory system secretes virulence proteins, called effectors. Effectors are responsible for the alteration of tight junction (TJ) structure and function in intestinal epithelial cells. AvrA is a newly described bacterial effector found in Salmonella. We report here that AvrA expression stabilizes cell permeability and tight junctions in

Anne P. Liao; Elaine O. Petrof; Sumalatha Kuppireddi; Yun Zhao; Yinglin Xia; Erika C. Claud; Jun Sun; Niyaz Ahmed

2008-01-01

235

Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing.  

PubMed

Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the RXLRs and Crinklers. To gain insight into the repertoire of effectors used by B. lactucae to manipulate its host, we performed massively parallel sequencing of cDNA derived from B. lactucae spores and infected lettuce (Lactuca sativa) seedlings. From over 2.3 million 454 GS FLX reads, 59 618 contigs were assembled representing both plant and pathogen transcripts. Of these, 19 663 contigs were determined to be of B. lactucae origin as they matched pathogen genome sequences (SOLiD) that were obtained from >270 million reads of spore-derived genomic DNA. After correction of cDNA sequencing errors with SOLiD data, translation into protein models and filtering, 16 372 protein models remained, 1023 of which were predicted to be secreted. This secretome included elicitins, necrosis and ethylene-inducing peptide 1-like proteins, glucanase inhibitors and lectins, and was enriched in cysteine-rich proteins. Candidate host-translocated effectors included 78 protein models with RXLR effector features. In addition, we found indications for an unknown number of Crinkler-like sequences. Similarity clustering of secreted proteins revealed additional effector candidates. We provide a first look at the transcriptome of B. lactucae and its encoded effector arsenal. PMID:22293108

Stassen, Joost H M; Seidl, Michael F; Vergeer, Pim W J; Nijman, Isaäc J; Snel, Berend; Cuppen, Edwin; Van den Ackerveken, Guido

2012-02-01

236

Presence of effector CD8+ T cells in hepatitis C virus-exposed healthy seronegative donors.  

PubMed

CTL responses against multiple hepatitis C virus (HCV) epitopes were detected in 7 of 29 (24.1%) healthy family members (HFM) persistently exposed to chronically HCV-infected patients (HCV-HFM). These precursor CTL were at very low or undetectable frequencies, as determined by limiting dilution analysis. However, when HCV-specific effector CD8+ T cells, freshly isolated from PBMC of HCV-HFM, were assessed by a sensitive enzyme-linked immunospot assay, their frequencies were severalfold higher than those of precursor CTL. These results indicate that the two assays detect two functionally distinct T cell populations and that the effector cells are not assayed by the 51Cr-release assay. Furthermore, the combination of cell depletion and enzyme-linked immunospot analyses showed that the effector cells were confined into a CD8+ CD45RO+ CD28- population. The persistence of effector CD8+ T cells specific for both the structural and nonstructural viral proteins in uninfected HCV-HFM, suggest that: 1) an immunological memory is established upon a subclinical infection without any evidence of hepatitis, in a large cohort of HCV-exposed individuals; 2) because these cells required neither restimulation nor the addition of particular cytokines in vitro for differentiating in effectors, they should be capable of prompt HCV-specific effector function in vivo, possibly providing antiviral protection; and 3) the maintenance of effector T cell responses may be sustained by persisting low-level stimulation induced by inapparent infections. PMID:10352286

Scognamiglio, P; Accapezzato, D; Casciaro, M A; Cacciani, A; Artini, M; Bruno, G; Chircu, M L; Sidney, J; Southwood, S; Abrignani, S; Sette, A; Barnaba, V

1999-06-01

237

The potential of effector-target genes in breeding for plant innate immunity.  

PubMed

Increasing numbers of infectious crop diseases that are caused by fungi and oomycetes urge the need to develop alternative strategies for resistance breeding. As an alternative for the use of resistance (R) genes, the application of mutant susceptibility (S) genes has been proposed as a potentially more durable type of resistance. Identification of S genes is hampered by their recessive nature. Here we explore the use of pathogen-derived effectors as molecular probes to identify S genes. Effectors manipulate specific host processes thereby contributing to disease. Effector targets might therefore represent S genes. Indeed, the Pseudomonas syringae effector HopZ2 was found to target MLO2, an Arabidopsis thaliana homologue of the barley S gene Mlo. Unfortunately, most effector targets identified so far are not applicable as S genes due to detrimental effects they have on other traits. However, some effector targets such as Mlo are successfully used, and with the increase in numbers of effector targets being identified, the numbers of S genes that can be used in resistance breeding will rise as well. PMID:23279965

Gawehns, Fleur; Cornelissen, Ben J C; Takken, Frank L W

2012-12-27

238

Bacteriophage-encoded type III effectors in Salmonella enterica subspecies 1 serovar Typhimurium.  

PubMed

Salmonella spp. are Gram-negative bacteria which cause infections ranging from mild, self-limiting enterocolitis to systemic (typhoid) disease. Recent work has established that the genetic makeup varies considerably between different Salmonella strains. Phages play an important role in this diversity. In fact, Salmonella has emerged as a prime example for the involvement of virulence factor encoding phages in the emergence of new epidemic strains. Among other virulence factors, Salmonella enterica utilizes two specialized protein secretion systems termed type III secretion systems (TTSS) to deliver effector proteins into host cells which manipulate host cell signaling cascades. These two TTSS and several effectors are encoded within Salmonella pathogenicity islands 1 and 2. Some effectors including SopE, SspH1, SseI and SopE2 are encoded by phages or phage remnants. These phage-encoded effectors seem to be transferred between different Salmonella strains. They have attracted much interest because they might contribute to the evolution of Salmonella spp. Here we will focus on SopEPhi which encodes the SPI-1 effector SopE. It provides an excellent example to illustrate how horizontally transferred effector proteins are integrated into the complex regulatory network of a TTSS in a recipient bacterium. Additional data supporting the hypothesis are presented. This is a prerequisite to allow optimization of the bacterium host cell interaction by reassortment of the phage-encoded effector protein repertoire. PMID:15567133

Ehrbar, Kristin; Hardt, Wolf-Dietrich

2005-01-01

239

A simple yeast-based strategy to identify host cellular processes targeted by bacterial effector proteins.  

PubMed

Bacterial effector proteins, which are delivered into the host cell via the type III secretion system, play a key role in the pathogenicity of gram-negative bacteria by modulating various host cellular processes to the benefit of the pathogen. To identify cellular processes targeted by bacterial effectors, we developed a simple strategy that uses an array of yeast deletion strains fitted into a single 96-well plate. The array is unique in that it was optimized computationally such that despite the small number of deletion strains, it covers the majority of genes in the yeast synthetic lethal interaction network. The deletion strains in the array are screened for hypersensitivity to the expression of a bacterial effector of interest. The hypersensitive deletion strains are then analyzed for their synthetic lethal interactions to identify potential targets of the bacterial effector. We describe the identification, using this approach, of a cellular process targeted by the Xanthomonas campestris type III effector XopE2. Interestingly, we discover that XopE2 affects the yeast cell wall and the endoplasmic reticulum stress response. More generally, the use of a single 96-well plate makes the screening process accessible to any laboratory and facilitates the analysis of a large number of bacterial effectors in a short period of time. It therefore provides a promising platform for studying the functions and cellular targets of bacterial effectors and other virulence proteins. PMID:22110728

Bosis, Eran; Salomon, Dor; Sessa, Guido

2011-11-15

240

Quantum entanglement suppression  

NASA Astrophysics Data System (ADS)

Individuality of microparticles (e.g., of ions or atoms) interacting with their environments (e.g., with the solvent molecules) is an open question of both physical and chemical kinetic theories. A qualitative proposal of Primas, and its later elaboration due to Amann, offers a background in this regard. Actually, they suggest that suppression of quantum entanglement provides a basis for the solution of the problem. Here, we show that the model of the so-called DISD ("decoherence-induced suppression of decoherence") method naturally and straightforwardly fits the basic assumptions of Amann's proposal and, therefore, might represent the missing link to the complete solution of the problem at hand.

Dugic, M.

2002-10-01

241

Regulatory T cells negatively affect IL-2 production of effector T cells through CD39/adenosine pathway in HIV infection.  

PubMed

The mechanisms by which Regulatory T cells suppress IL-2 production of effector CD4+ T cells in pathological conditions are unclear. A subpopulation of human Treg expresses the ectoenzyme CD39, which in association with CD73 converts ATP/ADP/AMP to adenosine. We show here that Treg/CD39+ suppress IL-2 expression of activated CD4+ T-cells more efficiently than Treg/CD39-. This inhibition is due to the demethylation of an essential CpG site of the il-2 gene promoter, which was reversed by an anti-CD39 mAb. By recapitulating the events downstream CD39/adenosine receptor (A2AR) axis, we show that A2AR agonist and soluble cAMP inhibit CpG site demethylation of the il-2 gene promoter. A high frequency of Treg/CD39+ is associated with a low clinical outcome in HIV infection. We show here that CD4+ T-cells from HIV-1 infected individuals express high levels of A2AR and intracellular cAMP. Following in vitro stimulation, these cells exhibit a lower degree of demethylation of il-2 gene promoter associated with a lower expression of IL-2, compared to healthy individuals. These results extend previous data on the role of Treg in HIV infection by filling the gap between expansion of Treg/CD39+ in HIV infection and the suppression of CD4+ T-cell function through inhibition of IL-2 production. PMID:23658513

Jenabian, Mohammad-Ali; Seddiki, Nabila; Yatim, Ahmad; Carriere, Matthieu; Hulin, Anne; Younas, Mehwish; Ghadimi, Elnaz; Kök, Ayrin; Routy, Jean-Pierre; Tremblay, Alain; Sévigny, Jean; Lelievre, Jean-Daniel; Levy, Yves

2013-04-25

242

Lessons from Anaplasma phagocytophilum: Chromatin Remodeling by Bacterial Effectors  

PubMed Central

Bacterial pathogens can alter global host gene expression via histone modifications and chromatin remodeling in order to subvert host responses, including those involved with innate immunity, allowing for bacterial survival. Shigella flexneri, Listeria monocytogenes, Chlamydia trachomatis, and Anaplasma phagocytophilum express effector proteins that modify host histones and chromatin structure. A. phagocytophilum modulates granulocyte respiratory burst in part by dampening transcription of several key phagocyte oxidase genes. The A. phagocytophilum protein AnkA localizes to the myeloid cell nucleus where it binds AT-rich regions in the CYBB promoter and decreases its transcription. AT-rich regions of DNA are characteristic of matrix attachment regions (MARs) which are critical for chromatin structure and transcription. MAR-binding proteins, such as SATB1, interact with histone modifying enzymes resulting in altered gene expression. With A. phagocytophilum infection, histone deacetylase 1 (HDAC1) expression is increased and histone H3 acetylation is decreased at the CYBB promoter, suggesting a role for AnkA in altering host epigenetics and modulating gene transcription, at this, and perhaps other loci. This review will focus on how bacterial pathogens alter host epigenetics, by specifically examining A. phagocytophilum AnkA cis-regulation of CYBB transcription and epigenetic changes associated with infection.

Rennoll-Bankert, Kristen E; Dumler, J Stephen

2012-01-01

243

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.

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

2013-01-01

244

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.

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

2010-01-01

245

Receptor-coupled effector systems and their interactions  

SciTech Connect

We investigated the modulation of intracellular signal generation by receptor-coupled effector systems in B lymphocytes, and whether these alterations are consistent with the effects of prostaglandins. TPA (12-O-tetradecanoyl phorbol-13-acetate) and sn-1,2,-dioctanoylglycerol (diC{sub 8}) substitute for lipid derived signals which activate protein kinase C. Pretreating splenocytes from athymic nude mice with 100nM TPA or 5 {mu}M diC{sub 8} potentiated the forskolin-induced increased in cAMP (measured by radioimmunoassay) 2.5 and 3.0 times (respectively), but they decreased the PGE{sub 1}-induced cAMP rise 48% and 35% (respectively). Goat anti-mouse IgM, which activates diacylglycerol production, potentiated the forskolin-induced cAMP increase by 76%, but reduced that of PGE{sub 1} by 30%. Rabbit anti-mouse IgG, its F(ab{prime}){sub 2} fragment, or goat anti-mouse IGM induced increases in the cytosolic free (Ca{sup 2+}), (Ca{sup 2+}){sub i}, which TPA inhibited. In contrast, TPA potential antibody-induced {sup 3}H-thymidine (85x) and {sup 3}H-uridine (30x) uptake in B lymphocytes.

Wiener, E.C.

1988-01-01

246

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.

Kufer, Thomas A.; Schwarzenbacher, Robert

2009-01-01

247

Effector selection precedes reach planning in the dorsal parietofrontal cortex  

PubMed Central

Experimental evidence and computational modeling suggest that target selection for reaching is associated with the parallel encoding of multiple movement plans in the dorsomedial posterior parietal cortex (dmPPC) and the caudal part of the dorsal premotor cortex (PMdc). We tested the hypothesis that a similar mechanism also accounts for arm selection for unimanual reaching, with simultaneous and separate motor goal representations for the left and right arms existing in the right and left parietofrontal cortex, respectively. We recorded simultaneous electroencephalograms and functional MRI and studied a condition in which subjects had to select the appropriate arm for reaching based on the color of an appearing visuospatial target, contrasting it to a condition in which they had full knowledge of the arm to be used before target onset. We showed that irrespective of whether subjects had to select the arm or not, activity in dmPPC and PMdc was only observed contralateral to the reaching arm after target onset. Furthermore, the latency of activation in these regions was significantly delayed when arm selection had to be achieved during movement planning. Together, these results demonstrate that effector selection is not achieved through the simultaneous specification of motor goals tied to the two arms in bilateral parietofrontal cortex, but suggest that a motor goal is formed in these regions only after an arm is selected for action.

Cieslak, Matthew; Grafton, Scott T.

2012-01-01

248

Motor resonance in left- and right-handers: evidence for effector-independent motor representations  

PubMed Central

The idea of motor resonance was born at the time that it was demonstrated that cortical and spinal pathways of the motor system are specifically activated during both action-observation and execution. What is not known is if the human action observation-execution matching system simulates actions through motor representations specifically attuned to the laterality of the observed effectors (i.e., effector-dependent representations) or through abstract motor representations unconnected to the observed effector (i.e., effector-independent representations). To answer that question we need to know how the information necessary for motor resonance is represented or integrated within the representation of an effector. Transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) were thus recorded from the dominant and non-dominant hands of left- and right-handed participants while they observed a left- or a right-handed model grasping an object. The anatomical correspondence between the effector being observed and the observer's effector classically reported in the literature was confirmed by the MEP response in the dominant hand of participants observing models with their same hand preference. This effect was found in both left- as well as in right-handers. When a broader spectrum of options, such as actions performed by a model with a different hand preference, was instead considered, that correspondence disappeared. Motor resonance was noted in the observer's dominant effector regardless of the laterality of the hand being observed. This would indicate that there is a more sophisticated mechanism which works to convert someone else's pattern of movement into the observer's optimal motor commands and that effector-independent representations specifically modulate motor resonance.

Sartori, Luisa; Begliomini, Chiara; Castiello, Umberto

2012-01-01

249

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

PubMed Central

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. Surprisingly, oomycete effectors seem to share a common uptake system with those from the human malaria pathogen. 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.

Panstruga, Ralph; Dodds, Peter N.

2009-01-01

250

Suppressing the Zs.  

ERIC Educational Resources Information Center

|In the frameword of generalized phrase-structure grammar, possessive clitics (POSS), bound words (BWs), and phrasal affixes (PAs) are analyzed. It is argued that English POSS should be treated as an edge-located inflectional affix, since POSS is suppressed in the presence of other Z affixes (plural, other possessives). (Author/LMO)|

Zwicky, A. M.

1987-01-01

251

Sensory suppression during feeding  

PubMed Central

Feeding is essential for survival, whereas withdrawal and escape reactions are fundamentally protective. These critical behaviors can compete for an animal's resources when an acutely painful stimulus affects the animal during feeding. One solution to the feeding-withdrawal conflict is to optimize feeding by suppressing pain. We examined whether rats continue to feed when challenged with a painful stimulus. During feeding, motor withdrawal responses to noxious paw heat either did not occur or were greatly delayed. To investigate the neural basis of sensory suppression accompanying feeding, we recorded from brainstem pain-modulatory neurons involved in the descending control of pain transmission. During feeding, pain-facilitatory ON cells were inhibited and pain-inhibitory OFF cells were excited. When a nonpainful somatosensory stimulus preactivated ON cells and preinhibited OFF cells, rats interrupted eating to react to painful stimuli. Inactivation of the brainstem region containing ON and OFF cells also blocked pain suppression during eating, demonstrating that brainstem pain-modulatory neurons suppress motor reactions to external stimulation during homeostatic behaviors.

Foo, H.; Mason, Peggy

2005-01-01

252

Drug Insight: appetite suppressants  

Microsoft Academic Search

The term 'appetite suppressant' is used to denote drugs that act primarily on the neurochemical transmitters of the central nervous system to reduce food intake. In addition to drugs that release or mimic the effect of norepinephrine (noradrenaline), this could include drugs that inhibit: reuptake of norepinephrine or 5-hydroxytryptamine (also known as serotonin); bind to the ?-aminobutyric acid receptors or

George A Bray

2005-01-01

253

Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations  

PubMed Central

Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints.

Rouxel, Thierry; Grandaubert, Jonathan; Hane, James K.; Hoede, Claire; van de Wouw, Angela P.; Couloux, Arnaud; Dominguez, Victoria; Anthouard, Veronique; Bally, Pascal; Bourras, Salim; Cozijnsen, Anton J.; Ciuffetti, Lynda M.; Degrave, Alexandre; Dilmaghani, Azita; Duret, Laurent; Fudal, Isabelle; Goodwin, Stephen B.; Gout, Lilian; Glaser, Nicolas; Linglin, Juliette; Kema, Gert H. J.; Lapalu, Nicolas; Lawrence, Christopher B.; May, Kim; Meyer, Michel; Ollivier, Benedicte; Poulain, Julie; Schoch, Conrad L.; Simon, Adeline; Spatafora, Joseph W.; Stachowiak, Anna; Turgeon, B. Gillian; Tyler, Brett M.; Vincent, Delphine; Weissenbach, Jean; Amselem, Joelle; Quesneville, Hadi; Oliver, Richard P.; Wincker, Patrick; Balesdent, Marie-Helene; Howlett, Barbara J.

2011-01-01

254

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.

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

2010-01-01

255

Regulation of vesicular trafficking and leukocyte function by Rab27 GTPases and their effectors.  

PubMed

The Rab27 family of GTPases regulates the efficiency and specificity of exocytosis in hematopoietic cells, including neutrophils, CTLs, NK cells, and mast cells. However, the mechanisms regulated by Rab27 GTPases are cell-specific, as they depend on the differential expression and function of particular effector molecules that are recruited by the GTPases. In addition, Rab27 GTPases participate in multiple steps of the regulation of the secretory process, including priming, tethering, docking, and fusion through sequential interaction with multiple effector molecules. Finally, recent reports suggest that Rab27 GTPases and their effectors regulate vesicular trafficking mechanisms other than exocytosis, including endocytosis and phagocytosis. This review focuses on the latest discoveries on the function of Rab27 GTPases and their effectors Munc13-4 and Slp1 in neutrophil function comparatively to their functions in other leukocytes. PMID:23378593

Catz, Sergio Daniel

2013-02-01

256

Structural consequences of effector protein complex formation in a diiron hydroxylase  

SciTech Connect

Carboxylate-bridged diiron hydroxylases are multicomponent enzyme complexes responsible for the catabolism of a wide range of hydrocarbons and as such have drawn attention for their mechanism of action and potential uses in bioremediation and enzymatic synthesis. These enzyme complexes use a small molecular weight effector protein to modulate the function of the hydroxylase. However, the origin of these functional changes is poorly understood. Here, we report the structures of the biologically relevant effector protein-hydroxylase complex of toluene 4-monooxygenase in 2 redox states. The structures reveal a number of coordinated changes that occur up to 25 {angstrom} from the active site and poise the diiron center for catalysis. The results provide a structural basis for the changes observed in a number of the measurable properties associated with effector protein binding. This description provides insight into the functional role of effector protein binding in all carboxylate-bridged diiron hydroxylases.

Bailey, Lucas J.; McCoy, Jason G.; Phillips, Jr., George N.; Fox, Brian G. (UW)

2009-06-12

257

Potential Application of Robotics and State-of-the Art End Effectors at Letterkenny Army Depot.  

National Technical Information Service (NTIS)

Letterkenny Army Depot has targeted areas for potential automation in the intermediate term using robotics. Areas of consideration include the interface of a high technology end effector with a currently planned robotics system. The area in mind is the ag...

J. Nitterhouse S. Kalabokes

1983-01-01

258

Concomitant suppression of three target genes can explain the impact of a microRNA on metastasis  

PubMed Central

It remains unclear whether a microRNA (miRNA) affects a given phenotype via concomitant down-regulation of its entire repertoire of targets or instead by suppression of only a modest subset of effectors. We demonstrate that inhibition of breast cancer metastasis by miR-31—a miRNA predicted to modulate >200 mRNAs—can be entirely explained by miR-31's pleiotropic regulation of three targets. Thus, concurrent re-expression of integrin-?5, radixin, and RhoA abrogates miR-31-imposed metastasis suppression. These effectors influence distinct steps of the metastatic process. Our findings have implications concerning the importance of pleiotropy for the biological actions of miRNAs and provide mechanistic insights into metastasis.

Valastyan, Scott; Benaich, Nathan; Chang, Amelia; Reinhardt, Ferenc; Weinberg, Robert A.

2009-01-01

259

The Rab5 Effector Rabankyrin-5 Regulates and Coordinates Different Endocytic Mechanisms  

Microsoft Academic Search

The small GTPase Rab5 is a key regulator of clathrin-mediated endocytosis. On early endosomes, within a spatially restricted domain enriched in phosphatydilinositol-3-phosphate [PI(3)P], Rab5 coordinates a complex network of effectors that functionally cooperate in membrane tethering, fusion, and organelle motility. Here we discovered a novel PI(3)P-binding Rab5 effector, Rabankyrin-5, which localises to early endosomes and stimulates their fusion activity. In

Carsten Schnatwinkel; Savvas Christoforidis; Margaret R Lindsay; Sandrine Uttenweiler-Joseph; Matthias Wilm; Robert G Parton; Marino Zerial

2004-01-01

260

Cutting Edge: Induction of Follicular Homing Precedes Effector Th Cell Development1  

Microsoft Academic Search

Transition from naive to Ag-experienced effector\\/memory CD4 T cells is initiated during contact with APC in secondary lymphoid tissue. Here, we demonstrate that the CXCR5 is a marker for recently activated memory CD4 T cells. CXCR5 is rapidly induced during contact with Ag-presenting dendritic cells, well before T cell expansion and effector cell develop- ment, and is irreversibly lost on

Patrick Schaerli; Pius Loetscher; Bernhard Moser

261

Human Natural Killer T Cells Are Heterogeneous in Their Capacity to Reprogram Their Effector Functions  

Microsoft Academic Search

BackgroundNatural killer T (NKT) cells are a subset of T cells that help potentiate and regulate immune responses. Although human NKT cell subsets with distinct effector functions have been identified, it is unclear whether the effector functions of these subsets are imprinted during development or can be selectively reprogrammed in the periphery.ResultsWe found that neonatal NKT cells are predominantly CD4+

Karla A. Eger; Mark S. Sundrud; Alison A. Motsinger; Michelle Tseng; Luc Van Kaer; Derya Unutmaz; Douglas Nixon

2006-01-01

262

Retrofit reconfigurable flight control in the presence of control effector damage  

Microsoft Academic Search

In this paper the development and implementation of an integrated retrofit reconfigurable flight control design for control effector damage compensation is presented. The proposed damage-adaptive control system has the capability of detecting and identifying flight-critical actuator failures and control effector damage, and rejecting the state-dependent disturbances arising due to the asymmetry of the damaged vehicle. The proposed damage-adaptive control system

J. D. Boskovic; Sarah E. Bergstrom; Raman K. Mehra

2005-01-01

263

In vivo Modulation of Avidity in Highly Sensitive CD8(+) Effector T Cells Following Viral Infection.  

PubMed

Abstract Numerous studies have demonstrated a critical role for T cell avidity in predicting in vivo efficacy. Even though the measurement of avidity is now a routine assessment for the analysis of effector and memory T cell populations, our understanding of how this property is controlled in vivo at both the population and individual cell levels is limited. Our previous studies have identified high avidity as a property of the initial effector population generated in mice following respiratory virus infection. As the response progresses, lower avidity cells appear in the effector pool. The studies described here investigate the mechanistic basis of this in vivo regulation of avidity. We present data supporting in vivo avidity modulation within the early high avidity responders that results in a population of lower avidity effector cells. Changes in avidity were correlated with decreased lck expression and increased sensitivity to lck inhibitors in effector cells present at late versus early times postinfection. The possibility of tuning within select individual effectors is a previously unappreciated mechanism for the control of avidity in vivo. PMID:23971914

Holbrook, Beth C; Yammani, Rama D; Blevins, Lance K; Alexander-Miller, Martha A

2013-08-24

264

Computational prediction of type III and IV secreted effectors in Gram-negative bacteria  

SciTech Connect

In this review, we provide an overview of the methods employed by four recent papers that described novel methods for computational prediction of secreted effectors from type III and IV secretion systems in Gram-negative bacteria. The results of the studies in terms of performance at accurately predicting secreted effectors and similarities found between secretion signals that may reflect biologically relevant features for recognition. We discuss the web-based tools for secreted effector prediction described in these studies and announce the availability of our tool, the SIEVEserver (http://www.biopilot.org). Finally, we assess the accuracy of the three type III effector prediction methods on a small set of proteins not known prior to the development of these tools that we have recently discovered and validated using both experimental and computational approaches. Our comparison shows that all methods use similar approaches and, in general arrive at similar conclusions. We discuss the possibility of an order-dependent motif in the secretion signal, which was a point of disagreement in the studies. Our results show that there may be classes of effectors in which the signal has a loosely defined motif, and others in which secretion is dependent only on compositional biases. Computational prediction of secreted effectors from protein sequences represents an important step toward better understanding the interaction between pathogens and hosts.

McDermott, Jason E.; Corrigan, Abigail L.; Peterson, Elena S.; Oehmen, Christopher S.; Niemann, George; Cambronne, Eric; Sharp, Danna; Adkins, Joshua N.; Samudrala, Ram; Heffron, Fred

2011-01-01

265

Global DNA methylation remodeling accompanies CD8 T cell effector function.  

PubMed

The differentiation of CD8 T cells in response to acute infection results in the acquisition of hallmark phenotypic effector functions; however, the epigenetic mechanisms that program this differentiation process on a genome-wide scale are largely unknown. In this article, we report the DNA methylomes of Ag-specific naive and day-8 effector CD8 T cells following acute lymphocytic choriomeningitis virus infection. During effector CD8 T cell differentiation, DNA methylation was remodeled such that changes in DNA methylation at gene promoter regions correlated negatively with gene expression. Importantly, differentially methylated regions were enriched at cis-elements, including enhancers active in naive T cells. Differentially methylated regions were associated with cell type-specific transcription factor binding sites, and these transcription factors clustered into modules that define networks targeted by epigenetic regulation and control of effector CD8 T cell function. Changes in the DNA methylation profile following CD8 T cell activation revealed numerous cellular processes, cis-elements, and transcription factor networks targeted by DNA methylation. Together, the results demonstrated that DNA methylation remodeling accompanies the acquisition of the CD8 T cell effector phenotype and repression of the naive cell state. Therefore, these data provide the framework for an epigenetic mechanism that is required for effector CD8 T cell differentiation and adaptive immune responses. PMID:23956425

Scharer, Christopher D; Barwick, Benjamin G; Youngblood, Benjamin A; Ahmed, Rafi; Boss, Jeremy M

2013-08-16

266

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.

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

2013-01-01

267

IL-17-producing human peripheral regulatory T cells retain suppressive function  

PubMed Central

Although implicated in antagonistic functions, both regulatory T cells (Tregs) and Th17 effector cells play an important role in controlling autoimmune pathogenesis. Paradoxically, recent studies indicate that Tregs have the capacity to produce interleukin-17 (IL-17), although the ability of these cells to retain their suppressive function remains unknown. Here we report that human Tregs within the CD4+CD45RA?CD25highCCR6+HLA-DR?FoxP3+ population produce IL-17 when activated in the presence of the proinflammatory cytokines IL-1? and IL-6, whereas IL-17 secretion was inhibited by TGF?. To assess the ability of a single Treg to secrete IL-17 and to suppress in vitro immune function, we isolated clones from this population. We found that IL-17+/FoxP3+ Treg clones retain suppressive function and exhibit the plasticity to secrete IL-17 or suppress depending on the nature of the stimulus provided. IL-17 production by these Treg clones was accompanied by sustained FoxP3 expression and concomitant, but reversible, loss of suppressive activity. Our data demonstrate that at the single cell level a subset of in vitro suppressive FoxP3+ cells can be driven to secrete IL-17 under inflammatory conditions. These findings suggest a new mechanism by which inflammation can drive Tregs to secrete IL-17, thereby dampening suppression and promoting an inflammatory milieu.

Beriou, Gaelle; Costantino, Cristina M.; Ashley, Charles W.; Yang, Li; Kuchroo, Vijay K.; Hafler, David A.

2009-01-01

268

Vibrotactile suppression of tinnitus  

NASA Astrophysics Data System (ADS)

At the Society's 142nd meeting, the efficacy of high frequency bone conducted stimulation in suppressing tinnitus was presented. The hypothesized mechanism was the reprogramming of frequency tuning of auditory neurons in the central nervous system, secondarily to peripheral hearing loss. This mechanism is unlikely in cases of tinnitus in the presence of normal audiometric sensitivity. There is the possibility that hearing loss above 10 kHz can play a role in tinnitus, an association not thoroughly explored. Somatomotor stimulation influencing the quality of tinnitus has been reported, as have interconnections of the auditory and somatosensory systems. There would appear to be an evolutionary advantage of linking the sensorimotor organization of the external ear and the auditory function of the brainstem in sound localization. Thus, stimulation of the pinna and post auricular area may be a means of suppressing tinnitus. To that end a thin aluminum ceramic bimorph was constructed to fit on the inner surface of the pinna. When driven by low (<100 Hz) and high (>10 kHz) frequencies multiplied by MHz carriers, demodulation in the skin resulted in vibrotactile stimulation. Tactile stimulation was an adjunct to the high frequencies resulting in a multimodal suppressive effect in a small pilot study.

Lenhardt, Martin L.

2002-05-01

269

Tactile suppression of displacement.  

PubMed

In vision, the discovery of the phenomenon of saccadic suppression of displacement has made important contributions to the understanding of the stable world problem. Here, we report a similar phenomenon in the tactile modality. When scanning a single Braille dot with two fingers of the same hand, participants were asked to decide whether the dot was stationary or whether it was displaced from one location to another. The stimulus was produced by refreshable Braille devices that have dots that can be swiftly raised and recessed. In some conditions, the dot was stationary. In others, a displacement was created by monitoring the participant's finger position and by switching the dot activation when it was not touched by either finger. The dot displacement was of either 2.5 mm or 5 mm. We found that in certain cases, displaced dots were felt to be stationary. If the displacement was orthogonal to the finger movements, tactile suppression occurred effectively when it was of 2.5 mm, but when the displacement was of 5 mm, the participants easily detected it. If the displacement was medial-lateral, the suppression effect occurred as well, but less often when the apparent movement of the dot opposed the movement of the finger. In such cases, the stimulus appeared sooner than when the brain could predict it from finger movement, supporting a predictive rather than a postdictive differential processing hypothesis. PMID:20842353

Ziat, Mounia; Hayward, Vincent; Chapman, C Elaine; Ernst, Marc O; Lenay, Charles

2010-09-15

270

Glioma associated cancer-initiating cells induce immune suppression  

PubMed Central

Purpose Glioblastoma multiforme (GBM) is a lethal cancer that responds poorly to therapy. GBM cancer-initiating cells have been shown to mediate resistance to both chemotherapy and radiation; however, it is unknown to what extent these cells contribute to the profound immune suppression in GBM patients and if strategies that alter their differentiation state can reduce this immune suppression. Experimental Design We isolated a subpopulation of cells from GBMs that possessed the capacity for self-renewal, formed neurospheres in vitro, were capable of pluripotent differentiation and could initiate tumors in vivo. These cells immune phenotype was characterized including the elaboration of immunosuppressive cytokines and chemokines by enzyme-linked immunosorbent assay. Functional immunosuppressive properties were characterized based on the inhibition of T cell proliferation and effector responses, triggering of T cell apoptosis and the induction FoxP3+ regulatory T cells. Upon altering their differentiation state, the immune suppressive phenotype and functional assays were reevaluated. Results We found that the cancer-initiating cells markedly inhibited T cell proliferation and activation, induced regulatory T cells and triggered T cell apoptosis that were mediated by B7-H1 and soluble Galectin-3. These immunosuppressive properties were diminished upon altering the differentiation of the cancer-initiating cells. Conclusion Cancer-initiating cells contribute to tumor evasion of the immune surveillance and approaches that alter the differentiation state may have immune therapeutic potential.

Wei, Jun; Barr, Jason; Kong, Ling-Yuan; Wang, Yongtao; Wu, Adam; Sharma, Amit K.; Gumin, Joy; Henry, Verlene; Colman, Howard; Sawaya, Raymond; Lang, Frederick F.; Heimberger, Amy B.

2010-01-01

271

Regulatory T Cells in ? Irradiation-Induced Immune Suppression  

PubMed Central

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.

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

2012-01-01

272

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.

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

2010-01-01

273

Immune suppression by neutrophils and granulocytic myeloid-derived suppressor cells: similarities and differences.  

PubMed

Neutrophils are essential effector cells in the host defense against invading pathogens. Recently, novel neutrophil functions have emerged in addition to their classical anti-microbial role. One of these functions is the suppression of T cell responses. In this respect, neutrophils share similarities with granulocytic myeloid-derived suppressor cells (G-MDSCs). In this review, we will discuss the similarities and differences between neutrophils and G-MDSCs. Various types of G-MDSCs have been described, ranging from immature to mature cells shaping the immune response by different immune suppressive mechanisms. However, all types of G-MDSCs share distinct features of neutrophils, such as surface markers and morphology. We propose that G-MDSCs are heterogeneous and represent novel phenotypes of neutrophils, capable of suppressing the immune response. In this review, we will attempt to clarify the differences and similarities between neutrophils and G-MDSCs and attempt to facilitate further research. PMID:23423530

Pillay, Janesh; Tak, Tamar; Kamp, Vera M; Koenderman, Leo

2013-02-20

274

Either a Th17 or a Th1 effector response can drive autoimmunity: conditions of disease induction affect dominant effector category  

PubMed Central

Experimental autoimmune uveitis (EAU) represents autoimmune uveitis in humans. We examined the role of the interleukin (IL)-23–IL-17 and IL-12–T helper cell (Th)1 pathways in the pathogenesis of EAU. IL–23 but not IL-12 was necessary to elicit disease by immunization with the retinal antigen (Ag) interphotoreceptor retinoid-binding protein (IRBP) in complete Freund's adjuvant. IL-17 played a dominant role in this model; its neutralization prevented or reversed disease, and Th17 effector cells induced EAU in the absence of interferon (IFN)-?. In a transfer model, however, a polarized Th1 line could induce severe EAU independently of host IL-17. Furthermore, induction of EAU with IRBP-pulsed mature dendritic cells required generation of an IFN-?–producing effector response, and an IL-17 response by itself was insufficient to elicit pathology. Finally, genetic deficiency of IL-17 did not abrogate EAU susceptibility. Thus, autoimmune pathology can develop in the context of either a Th17 or a Th1 effector response depending on the model. The data suggest that the dominant effector phenotype may be determined at least in part by conditions present during initial exposure to Ag, including the quality/quantity of Toll-like receptor stimulation and/or type of Ag-presenting cells. These data also raise the possibility that the nonredundant requirement for IL-23 in EAU may extend beyond its role in promoting the Th17 effector response and help provide a balance in the current Th1 versus Th17 paradigm.

Luger, Dror; Silver, Phyllis B.; Tang, Jun; Cua, Daniel; Chen, Zoe; Iwakura, Yoichiro; Bowman, Edward P.; Sgambellone, Nicole M.; Chan, Chi-Chao; Caspi, Rachel R.

2008-01-01

275

Structures of the flax-rust effector AvrM reveal insights into the molecular basis of plant-cell entry and effector-triggered immunity.  

PubMed

Fungal and oomycete pathogens cause some of the most devastating diseases in crop plants, and facilitate infection by delivering a large number of effector molecules into the plant cell. AvrM is a secreted effector protein from flax rust (Melampsora lini) that can internalize into plant cells in the absence of the pathogen, binds to phosphoinositides (PIPs), and is recognized directly by the resistance protein M in flax (Linum usitatissimum), resulting in effector-triggered immunity. We determined the crystal structures of two naturally occurring variants of AvrM, AvrM-A and avrM, and both reveal an L-shaped fold consisting of a tandem duplicated four-helix motif, which displays similarity to the WY domain core in oomycete effectors. In the crystals, both AvrM variants form a dimer with an unusual nonglobular shape. Our functional analysis of AvrM reveals that a hydrophobic surface patch conserved between both variants is required for internalization into plant cells, whereas the C-terminal coiled-coil domain mediates interaction with M. AvrM binding to PIPs is dependent on positive surface charges, and mutations that abrogate PIP binding have no significant effect on internalization, suggesting that AvrM binding to PIPs is not essential for transport of AvrM across the plant membrane. The structure of AvrM and the identification of functionally important surface regions advance our understanding of the molecular mechanisms underlying how effectors enter plant cells and how they are detected by the plant immune system. PMID:24101475

Ve, Thomas; Williams, Simon J; Catanzariti, Ann-Maree; Rafiqi, Maryam; Rahman, Motiur; Ellis, Jeffrey G; Hardham, Adrienne R; Jones, David A; Anderson, Peter A; Dodds, Peter N; Kobe, Bostjan

2013-10-07

276

Naturally Occurring Nonpathogenic Isolates of the Plant Pathogen Pseudomonas syringae Lack a Type III Secretion System and Effector Gene Orthologues? †  

PubMed Central

Pseudomonas syringae causes plant diseases, and the main virulence mechanism is a type III secretion system (T3SS) that translocates dozens of effector proteins into plant cells. Here we report the existence of a subgroup of P. syringae isolates that do not cause disease on any plant species tested. This group is monophyletic and most likely evolved from a pathogenic P. syringae ancestor through loss of the T3SS. In the nonpathogenic isolate P. syringae 508 the genomic region that in pathogenic P. syringae strains contains the hrp-hrc cluster coding for the T3SS and flanking effector genes is absent. P. syringae 508 was also surveyed for the presence of effector orthologues from the closely related pathogenic strain P. syringae pv. syringae B728a, but none were detected. The absence of the hrp-hrc cluster and effector orthologues was confirmed for other nonpathogenic isolates. Using the AvrRpt2 effector as reporter revealed the inability of P. syringae 508 to translocate effectors into plant cells. Adding a plasmid-encoded T3SS and the P. syringae pv. syringae 61 effector gene hopA1 increased in planta growth almost 10-fold. This suggests that P. syringae 508 supplemented with a T3SS could be used to determine functions of individual effectors in the context of a plant infection, avoiding the confounding effect of other effectors with similar functions present in effector mutants of pathogenic isolates.

Mohr, Toni J.; Liu, Haijie; Yan, Shuangchun; Morris, Cindy E.; Castillo, Jose A.; Jelenska, Joanna; Vinatzer, Boris A.

2008-01-01

277

Signal integration by Akt regulates CD8 T cell effector and memory differentiation.  

PubMed

During a T cell response, the effector CTL pool contains two cellular subsets: short-lived effector cells (SLECs), a majority of which are destined for apoptosis, and the memory precursor effector cells, which differentiate into memory cells. Understanding the mechanisms that govern the differentiation of memory CD8 T cells is of fundamental importance in the development of effective CD8 T cell-based vaccines. The strength and nature of TCR signaling, along with signals delivered by cytokines like IL-2 and IL-12, influence differentiation of SLECs and memory precursor effector cells. A central question is, how are signals emanating from multiple receptors integrated and interpreted to define the fate of effector CTLs? Using genetic and pharmacological tools, we have identified Akt as a signal integrator that links distinct facets of CTL differentiation to the specific signaling pathways of FOXO, mTOR, and Wnt/?-catenin. Sustained Akt activation triggered by convergent extracellular signals evokes a transcription program that enhances effector functions, drives differentiation of terminal effectors, and diminishes the CTLs' potential to survive and differentiate into memory cells. Whereas sustained Akt activation severely impaired CD8 T cell memory and protective immunity, in vivo inhibition of Akt rescued SLECs from deletion and increased the number of memory CD8 T cells. Thus, the cumulative strength of convergent signals from signaling molecules such as TCR, costimulatory molecules, and cytokine receptors governs the magnitude of Akt activation, which in turn controls the generation of long-lived memory cells. These findings suggest that therapeutic modulation of Akt might be a strategy to augment vaccine-induced immunity. PMID:22467649

Kim, Eui Ho; Sullivan, Jeremy A; Plisch, Erin H; Tejera, Melba Marie; Jatzek, Anna; Choi, Kwan Yong; Suresh, M

2012-03-30

278

Inactivation of Hepatitis B Virus Replication in Cultured Cells and In Vivo with Engineered Transcription Activator-Like Effector Nucleases  

PubMed Central

Chronic hepatitis B virus (HBV) infection remains an important global health problem. Stability of the episomal covalently closed circular HBV DNA (cccDNA) is largely responsible for the modest curative efficacy of available therapy. Since licensed anti-HBV drugs have a post-transcriptional mechanism of action, disabling cccDNA is potentially of therapeutic benefit. To develop this approach, we engineered mutagenic transcription activator-like effector nucleases (TALENs) that target four HBV-specific sites within the viral genome. TALENs with cognate sequences in the S or C open-reading frames (ORFs) efficiently disrupted sequences at the intended sites and suppressed markers of viral replication. Following triple transfection of cultured HepG2.2.15 cells under mildly hypothermic conditions, the S TALEN caused targeted mutation in ~35% of cccDNA molecules. Markers of viral replication were also inhibited in vivo in a murine hydrodynamic injection model of HBV replication. HBV target sites within S and C ORFs of the injected HBV DNA were mutated without evidence of toxicity. These findings are the first to demonstrate a targeted nuclease-mediated disruption of HBV cccDNA. Efficacy in vivo also indicates that these engineered nucleases have potential for use in treatment of chronic HBV infection.

Bloom, Kristie; Ely, Abdullah; Mussolino, Claudio; Cathomen, Toni; Arbuthnot, Patrick

2013-01-01

279

Green tea epigallocatechin-3-gallate modulates differentiation of naïve CD4? T cells into specific lineage effector cells.  

PubMed

CD4(+) T helper (Th) subsets Th1, Th9, and Th17 cells are implicated in inducing autoimmunity whereas regulatory T cells (Treg) have a protective effect. We and others have previously shown that epigallocatechin-3-gallate (EGCG) attenuates experimental autoimmune encephalomyelitis (EAE) and alters CD4(+) T cell subpopulations. In this study, we investigated how EGCG impacts differentiation of naïve CD4(+) T cells into different effector lineages and report that EGCG impeded Th1, Th9, and Th17 differentiation and prevented IL-6-induced suppression of Treg development. We further showed that EGCG inhibited T-bet, PU.1, and ROR?t, the specific transcription factors for Th1, Th9, and Th17 differentiation, respectively. These effects, in turn, may be mediated by EGCG-induced downregulation of transducers p-STAT1 and p-STAT4 for Th1, and p-STAT3 for Th17. EGCG-induced change in Th17/Treg balance may be mediated by its inhibition of IL-6 signaling because EGCG inhibited soluble IL-6R, membrane gp130, and IL-6-induced phosphorylation of STAT3. This notion was further supported by the in vivo results showing inhibited IL-6 and soluble IL-6R but increased soluble gp130 levels in plasma from EAE mice fed EGCG. Together, our results suggest that EGCG modulates development of CD4(+) T cell lineages through impacting their respective and interactive regulatory networks ultimately leading to an attenuated autoimmune response. PMID:23064699

Wang, Junpeng; Pae, Munkyong; Meydani, Simin Nikbin; Wu, Dayong

2012-10-12

280

Preventing bacterial DNA release and absent in melanoma 2 inflammasome activation by a Legionella effector functioning in membrane trafficking  

PubMed Central

Legionella pneumophila, the causative agent of Legionnaires’ pneumonia, resides in a distinct vacuole structure called Legionella-containing vacuole (LCV). The LCV resists fusion with the lysosome and permits efficient bacterial replication in host macrophages, which requires a Dot/Icm type IVB secretion system. Dot/Icm-translocated effector SdhA is critical for L. pneumophila intracellular growth and functions to prevent host cell death. Here, we show that the absence of SdhA resulted in elevated caspase-1 activation and IL-1? secretion as well as macrophage pyroptosis during Legionella infection. These inflammasome activation phenotypes were independent of the established flagellin-NAIP5-NLRC4 axis, but relied on the DNA-sensing AIM2 inflammasome. We further demonstrate that Legionella DNA was released into macrophage cytosol, and this effect was significantly exaggerated by the absence of SdhA. SdhA bears a functional Golgi-targeting GRIP domain that is required for preventing AIM2 inflammasome activation. Ectopically expressed SdhA formed a unique ring-shape membrane structure, further indicating a role in membrane trafficking and maintaining LCV membrane integrity. Our data together suggest a possible link, mediated by the function of SdhA, between LCV trafficking/maturation and suppression of host innate immune detection.

Ge, Jianning; Gong, Yi-Nan; Xu, Ying; Shao, Feng

2012-01-01

281

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.

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

2012-01-01

282

Compatibility in the Ustilago maydis-Maize Interaction Requires Inhibition of Host Cysteine Proteases by the Fungal Effector Pit2  

PubMed Central

The basidiomycete Ustilago maydis causes smut disease in maize, with large plant tumors being formed as the most prominent disease symptoms. During all steps of infection, U. maydis depends on a biotrophic interaction, which requires an efficient suppression of plant immunity. In a previous study, we identified the secreted effector protein Pit2, which is essential for maintenance of biotrophy and induction of tumors. Deletion mutants for pit2 successfully penetrate host cells but elicit various defense responses, which stops further fungal proliferation. We now show that Pit2 functions as an inhibitor of a set of apoplastic maize cysteine proteases, whose activity is directly linked with salicylic-acid-associated plant defenses. Consequently, protease inhibition by Pit2 is required for U. maydis virulence. Sequence comparisons with Pit2 orthologs from related smut fungi identified a conserved sequence motif. Mutation of this sequence caused loss of Pit2 function. Consequently, expression of the mutated protein in U. maydis could not restore virulence of the pit2 deletion mutant, indicating that the protease inhibition by Pit2 is essential for fungal virulence. Moreover, synthetic peptides of the conserved sequence motif showed full activity as protease inhibitor, which identifies this domain as a new, minimal protease inhibitor domain in plant-pathogenic fungi.

Mueller, Andre N.; Ziemann, Sebastian; Treitschke, Steffi; Assmann, Daniela; Doehlemann, Gunther

2013-01-01

283

Tumor-Induced Disruption of Proximal TCR-Mediated Signal Transduction in Tumor-Infiltrating CD8+ Lymphocytes Inactivates Antitumor Effector Phase  

PubMed Central

The presence in cancer tissue of Ag-specific, activated tumor infiltrating CD8+ T cells proves that tumors express Ags capable of eliciting immune response. Therefore, in general, tumor escape from immune-mediated clearance is not attributable to immunological ignorance. However, tumor-infiltrating lymphocytes are defective in effector phase function, demonstrating tumor-induced immune suppression that likely underlies tumor escape. Since exocytosis of lytic granules is dependent upon TCR-mediated signal transduction, it is a reasonable contention that tumors may induce defective signal transduction in tumor infiltrating T cells. In this review, we consider the biochemical basis for antitumor T cell dysfunction, focusing on the role of inhibitory signaling receptors in restricting TCR-mediated signaling in tumor-infiltrating lymphocytes.

Vazquez-Cintron, Edwin J.; Monu, Ngozi R.; Frey, Alan B.

2013-01-01

284

Secreted Effector Proteins of Salmonella dublin Act in Concert To Induce Enteritis  

PubMed Central

The ability of enteropathogenic salmonellae to recruit inflammatory cells and induce secretory responses in the infected ileum is considered to be a main feature in Salmonella-induced enteritis. Interactions between the pathogen and intestinal epithelial cells result in a variety of cellular responses mediating inflammation and fluid secretion. It is becoming apparent that proteins secreted by the Inv-Spa type III secretion system of Salmonella spp. play a key role in the induction of these responses. We have recently demonstrated that the SopB effector protein is translocated into eukaryotic cells via a Sip-dependent pathway and mediates inflammation and fluid secretion in infected ileal mucosa. However, SopB did not appear to be the only effector involved, as inactivation of the sopB gene only partially impaired enteropathogenicity. We suggested that at least some of such protein effectors are likely to be proteins of the same class as SopB, i.e., secreted effector proteins translocated into eukaroyotic cells via a Sip-dependent pathway. In this work, we identify SopD, another secreted protein belonging to the family of Sop effectors of Salmonella dublin. Using the cya reporter system we showed that SopD is translocated into eukaroyotic cells. We assessed the potential involvement of SopD in enteropathogenicity and found that inactivation of sopD has an additive effect in relation to the sopB mutation.

Jones, Michael A.; Wood, Michael W.; Mullan, Paul B.; Watson, Patricia R.; Wallis, Tim S.; Galyov, Edouard E.

1998-01-01

285

Bacterial Guanine Nucleotide Exchange Factors SopE-Like and WxxxE Effectors?  

PubMed Central

Subversion of Rho family small GTPases, which control actin dynamics, is a common infection strategy used by bacterial pathogens. In particular, Salmonella enterica serovar Typhimurium, Shigella flexneri, enteropathogenic Escherichia coli (EPEC), and enterohemorrhagic Escherichia coli (EHEC) translocate type III secretion system (T3SS) effector proteins to modulate the Rho GTPases RhoA, Cdc42, and Rac1, which trigger formation of stress fibers, filopodia, and lamellipodia/ruffles, respectively. The Salmonella effector SopE is a guanine nucleotide exchange factor (GEF) that activates Rac1 and Cdc42, which induce “the trigger mechanism of cell entry.” Based on a conserved Trp-xxx-Glu motif, the T3SS effector proteins IpgB1 and IpgB2 of Shigella, SifA and SifB of Salmonella, and Map of EPEC and EHEC were grouped together into a WxxxE family; recent studies identified the T3SS EPEC and EHEC effectors EspM and EspT as new family members. Recent structural and functional studies have shown that representatives of the WxxxE effectors share with SopE a 3-D fold and GEF activity. In this minireview, we summarize contemporary findings related to the SopE and WxxxE GEFs in the context of their role in subverting general host cell signaling pathways and infection.

Bulgin, Richard; Raymond, Benoit; Garnett, James A.; Frankel, Gad; Crepin, Valerie F.; Berger, Cedric N.; Arbeloa, Ana

2010-01-01

286

Hierarchical Effector Protein Transport by the Salmonella Typhimurium SPI-1 Type III Secretion System  

PubMed Central

Background Type III secretion systems (TTSS) are employed by numerous pathogenic and symbiotic bacteria to inject a cocktail of different “effector proteins” into host cells. These effectors subvert host cell signaling to establish symbiosis or disease. Methodology/Principal Findings We have studied the injection of SipA and SptP, two effector proteins of the invasion-associated Salmonella type III secretion system (TTSS-1). SipA and SptP trigger different host cell responses. SipA contributes to triggering actin rearrangements and invasion while SptP reverses the actin rearrangements after the invasion has been completed. Nevertheless, SipA and SptP were both pre-formed and stored in the bacterial cytosol before host cell encounter. By time lapse microscopy, we observed that SipA was injected earlier than SptP. Computer modeling revealed that two assumptions were sufficient to explain this injection hierarchy: a large number of SipA and SptP molecules compete for transport via a limiting number of TTSS; and the TTSS recognize SipA more efficiently than SptP. Conclusions/Significance This novel mechanism of hierarchical effector protein injection may serve to avoid functional interference between SipA and SptP. An injection hierarchy of this type may be of general importance, allowing bacteria to precisely time the host cell manipulation by type III effectors.

Winnen, Brit; Schlumberger, Markus C.; Sturm, Alexander; Schupbach, Kaspar; Siebenmann, Stefan; Jenny, Patrick; Hardt, Wolf-Dietrich

2008-01-01

287

Bacterial guanine nucleotide exchange factors SopE-like and WxxxE effectors.  

PubMed

Subversion of Rho family small GTPases, which control actin dynamics, is a common infection strategy used by bacterial pathogens. In particular, Salmonella enterica serovar Typhimurium, Shigella flexneri, enteropathogenic Escherichia coli (EPEC), and enterohemorrhagic Escherichia coli (EHEC) translocate type III secretion system (T3SS) effector proteins to modulate the Rho GTPases RhoA, Cdc42, and Rac1, which trigger formation of stress fibers, filopodia, and lamellipodia/ruffles, respectively. The Salmonella effector SopE is a guanine nucleotide exchange factor (GEF) that activates Rac1 and Cdc42, which induce "the trigger mechanism of cell entry." Based on a conserved Trp-xxx-Glu motif, the T3SS effector proteins IpgB1 and IpgB2 of Shigella, SifA and SifB of Salmonella, and Map of EPEC and EHEC were grouped together into a WxxxE family; recent studies identified the T3SS EPEC and EHEC effectors EspM and EspT as new family members. Recent structural and functional studies have shown that representatives of the WxxxE effectors share with SopE a 3-D fold and GEF activity. In this minireview, we summarize contemporary findings related to the SopE and WxxxE GEFs in the context of their role in subverting general host cell signaling pathways and infection. PMID:20123714

Bulgin, Richard; Raymond, Benoit; Garnett, James A; Frankel, Gad; Crepin, Valerie F; Berger, Cedric N; Arbeloa, Ana

2010-02-01

288

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.

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

2010-01-01

289

Multiple redundant effector mechanisms of CD8+ T cells protect against influenza infection.  

PubMed

We have previously shown that mice challenged with a lethal dose of A/Puerto Rico/8/34-OVA(I) are protected by injection of 4-8 × 10(6) in vitro-generated Tc1 or Tc17 CD8(+) effectors. Viral load, lung damage, and loss of lung function are all reduced after transfer. Weight loss is reduced and survival increased. We sought in this study to define the mechanism of this protection. CD8(+) effectors exhibit multiple effector activities, perforin-, Fas ligand-, and TRAIL-mediated cytotoxicity, and secretion of multiple cytokines (IL-2, IL-4, IL-5, IL-9, IL-10, IL-17, IL-21, IL-22, IFN-?, and TNF) and chemokines (CCL3, CCL4, CCL5, CXCL9, and CXCL10). Transfer of CD8(+) effectors into recipients, before infection, elicits enhanced recruitment of host neutrophils, NK cells, macrophages, and B cells. All of these events have the potential to protect against viral infections. Removal of any one, however, of these potential mechanisms was without effect on protection. Even the simultaneous removal of host T cells, host B cells, and host neutrophils combined with the elimination of perforin-mediated lytic mechanisms in the donor cells failed to reduce their ability to protect. We conclude that CD8(+) effector T cells can protect against the lethal effects of viral infection by means of a large number of redundant mechanisms. PMID:23197262

Hamada, Hiromasa; Bassity, Elizabeth; Flies, Amanda; Strutt, Tara M; Garcia-Hernandez, Maria de Luz; McKinstry, K Kai; Zou, Tie; Swain, Susan L; Dutton, Richard W

2012-11-28

290

Factors influencing dust suppressant effectiveness  

SciTech Connect

Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. The length of time after application that suppressants were effective was also improved by using hygroscopic reagents that retained moisture to prevent evaporation. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

Copeland, C.R.; Eisele, T.C.; Chesney, D.J.; Kawatra, S.K. [Michigan Technology University, Houghton, MI (United States). Dept. of Chemical Engineering

2008-11-15

291

Recombinant vaccines based on translocated effector proteins of Salmonella Pathogenicity Island 2.  

PubMed

Attenuated live Salmonella enterica are useful carriers for the delivery of heterologous antigens for vaccination. Effector proteins translocated by type III secretion systems (T3SS) of Salmonella have been successfully utilized for antigen delivery. Here we investigated the use of effector proteins of the T3SS encoded by Salmonella Pathogenicity Island 2 (SPI2). We observed that the effector protein SseF is suitable for delivery of various fusion proteins with heterologous antigens. The efficiency of this carrier protein was demonstrated in vaccination experiments with fusion proteins with Listeria monocytogenes protective antigens. SseF can thus be used as a versatile vehicle for translocation of heterologous proteins for vaccination. PMID:16887239

Husseiny, Mohamed I; Wartha, Florian; Hensel, Michael

2005-11-22

292

Volumetric reach comparison of possible end-effectors for the articulated transporter and manipulator system  

SciTech Connect

The goal of this research was to investigate the performance of the Articulated Transporter and Manipulator System (ATMS) during various tasks relative to the choice of wrist/end-effector configuration. The approach taken was to generate computer graphics-aided three-dimensional interactive application (CATIA) system-based models of four wrist/end-effector combinations and consider the volumetric reach of each of these configurations based on the capacity of the ATMS. The results indicate that a simple, lightweight end-effector provides a greater volumetric reach. The greatest variation presented herein is {approximately}40% when comparing a 7-degree-of-freedom (DOF) dexterous arm with a simple 3-DOF arm; however, the benefit of increasing volumetric reach by only 40% by using a simple arm may be outweighed by the loss of dexterity. 10 refs., 5 figs., 3 tabs.

Kress, R.L.; Babcock, S.M.; Hamel, W.R. (Oak Ridge National Lab., TN (USA)); Bills, K.C. (Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA))

1990-01-01

293

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.

Canonne, Joanne; Rivas, Susana

2012-01-01

294

Structural Basis for Sequence-Specific Recognition of DNA by TAL Effectors  

PubMed Central

TAL (transcription activator–like) effectors, secreted by phytopathogenic bacteria, recognize host DNA sequences through a central domain of tandem repeats. Each repeat comprises 33 to 35 conserved amino acids and targets a specific base pair by using two hypervariable residues [known as repeat variable diresidues (RVDs)] at positions 12 and 13. Here, we report the crystal structures of an 11.5-repeat TAL effector in both DNA-free and DNA-bound states. Each TAL repeat comprises two helices connected by a short RVD-containing loop. The 11.5 repeats form a right-handed, superhelical structure that tracks along the sense strand of DNA duplex, with RVDs contacting the major groove. The 12th residue stabilizes the RVD loop, whereas the 13th residue makes a base-specific contact. Understanding DNA recognition by TAL effectors may facilitate rational design of DNA-binding proteins with biotechnological applications.

Deng, Dong; Yan, Chuangye; Pan, Xiaojing; Mahfouz, Magdy; Wang, Jiawei; Zhu, Jian-Kang; Shi, Yigong; Yan, Nieng

2013-01-01

295

Osteoclast Activated FoxP3+ CD8+ T-Cells Suppress Bone Resorption in vitro  

PubMed Central

Background Osteoclasts are the body’s sole bone resorbing cells. Cytokines produced by pro-inflammatory effector T-cells (TEFF) increase bone resorption by osteoclasts. Prolonged exposure to the TEFF produced cytokines leads to bone erosion diseases such as osteoporosis and rheumatoid arthritis. The crosstalk between T-cells and osteoclasts has been termed osteoimmunology. We have previously shown that under non-inflammatory conditions, murine osteoclasts can recruit naïve CD8 T-cells and activate these T-cells to induce CD25 and FoxP3 (TcREG). The activation of CD8 T-cells by osteoclasts also induced the cytokines IL-2, IL-6, IL-10 and IFN-?. Individually, these cytokines can activate or suppress osteoclast resorption. Principal Findings To determine the net effect of TcREG on osteoclast activity we used a number of in vitro assays. We found that TcREG can potently and directly suppress bone resorption by osteoclasts. TcREG could suppress osteoclast differentiation and resorption by mature osteoclasts, but did not affect their survival. Additionally, we showed that TcREG suppress cytoskeletal reorganization in mature osteoclasts. Whereas induction of TcREG by osteoclasts is antigen-dependent, suppression of osteoclasts by TcREG does not require antigen or re-stimulation. We demonstrated that antibody blockade of IL-6, IL-10 or IFN-? relieved suppression. The suppression did not require direct contact between the TcREG and osteoclasts. Significance We have determined that osteoclast-induced TcREG can suppress osteoclast activity, forming a negative feedback system. As the CD8 T-cells are activated in the absence of inflammatory signals, these observations suggest that this regulatory loop may play a role in regulating skeletal homeostasis. Our results provide the first documentation of suppression of osteoclast activity by CD8 regulatory T-cells and thus, extend the purview of osteoimmunology.

Buchwald, Zachary S.; Kiesel, Jennifer R.; DiPaolo, Richard; Pagadala, Meghana S.; Aurora, Rajeev

2012-01-01

296

Pollutant suppression device  

SciTech Connect

A pollutant suppression device is described comprising: a power supply, means for generating liquid droplets, and a charging head, the charging head being electrically connected to the power supply, the charging head being positioned to receive the droplets from the generating means and to induce an electrostatic charge onto the droplets, and the charging head comprising at least two generally concentric rings, the outer ring being constructed of an insulating plastic material having a resistivity greater than about 10/sup 12/ ohm-cm, the inner ring being constructed of a generally insulating plastic material having a resistivity in the range of about 10/sup 8/ ohm-cm to about 10/sup 10/ ohm-cm.

Hastings, E.E.

1987-06-02

297

ZERO SUPPRESSION FOR RECORDERS  

DOEpatents

A zero-suppression circuit for self-balancing recorder instruments is presented. The essential elements of the circuit include a converter-amplifier having two inputs, one for a reference voltage and the other for the signal voltage under analysis, and a servomotor with two control windings, one coupled to the a-c output of the converter-amplifier and the other receiving a reference input. Each input circuit to the converter-amplifier has a variable potentiometer and the sliders of the potentiometer are ganged together for movement by the servoinotor. The particular noveity of the circuit resides in the selection of resistance values for the potentiometer and a resistor in series with the potentiometer of the signal circuit to ensure the full value of signal voltage variation is impressed on a recorder mechanism driven by servomotor.

Fort, W.G.S.

1958-12-30

298

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

299

Ultrasonic Frost Suppression  

NASA Astrophysics Data System (ADS)

The authors have observed the accumulation of frost on the surface of a rectangular aluminum alloy (duralumin) plate flexurally vibrating at approximately 37 kHz in an atmosphere of almost 100% relative humidity at 2°C. The plate surface, which had been prepolished with abrasive slurry for maintaining its average surface roughness of about 100 nm, was refrigerated at a temperature of -20°C with cold carbon-dioxide gas as coolant. Experiments have been conducted with and without fine silver oxide powder spread on the plate surface so as to examine the effect of artificial ice crystal nuclei. Ultrasonic vibrations with an amplitude of 3.4 ?m (rms) are found to suppress frost accumulation by approximately 60%. The phenomenon cannot be ascribed directly to the heat generation caused by high-amplitude vibration, but may have a complex mechanical and/or acoustical effect on small ice crystals.

Adachi, Kazunari; Saiki, Kazushi; Sato, Hiroki; Ito, Takahiro

2003-02-01

300

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

301

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); Peter N. Dodds (Commonwealth Scientific and Industrial Research Organization Plant Industry;)

2009-05-08

302

Design criteria for the light duty utility arm system end effectors  

SciTech Connect

This document provides the criteria for the design of end effectors that will be used as part of the Light Duty Utility Arm (LDUA) System. The LDUA System consists of a deployment vehicle, a vertical positioning mast, a light duty multi-axis robotic arm, a tank riser interface and confinement, a tool interface plate, a control system, and an operations control trailer. The criteria specified in this document will apply to all end effector systems being developed for use on or with the LDUA system at the Hanford site. The requirement stipulated in this document are mandatory.

Pardini, A.F.

1995-01-03

303

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.

Geissler, Brett

2012-01-01

304

Learning motion discrimination with suppressed and un-suppressed MT  

Microsoft Academic Search

Perceptual learning of motion direction discrimination is generally thought to rely on the middle temporal area of the brain (MT\\/V5). A recent study investigating learning of motion discrimination when MT was psychophysically suppressed found that learning was possible with suppressed MT, but only when the task was sufficiently easy [Lu, H., Qian, N., Liu, Z. (2004). Learning motion discrimination with

Benjamin Thompson; Zili Liu

2006-01-01

305

Treg-mediated suppression of atherosclerosis requires MYD88 signaling in DCs  

PubMed Central

TLR activation on CD11c+ DCs triggers DC maturation, which is critical for T cell activation. Given the expansion of CD11c+ DCs during the progression of atherosclerosis and the key role of T cell activation in atherogenesis, we sought to understand the role of TLR signaling in CD11c+ DCs in atherosclerosis. To this end, we used a mouse model in which a key TLR adaptor involved in DC maturation, MYD88, is deleted in CD11c+ DCs. We transplanted bone marrow containing Myd88-deficient CD11c+ DCs into Western diet–fed LDL receptor knockout mice and found that the transplanted mice had decreased activation of effector T cells in the periphery as well as decreased infiltration of both effector T cells and Tregs in atherosclerotic lesions. Surprisingly, the net effect was an increase in atherosclerotic lesion size due to an increase in the content of myeloid-derived inflammatory cells. The mechanism involves increased lesional monocyte recruitment associated with loss of Treg-mediated suppression of MCP-1. Thus, the dominant effect of MYD88 signaling in CD11c+ DCs in the setting of atherosclerosis is to promote the development of atheroprotective Tregs. In the absence of MYD88 signaling in CD11c+ DCs, the loss of this protective Treg response trumps the loss of proatherogenic T effector cell activation.

Subramanian, Manikandan; Thorp, Edward; Hansson, Goran K.; Tabas, Ira

2012-01-01

306

Regulatory role of suppressive motifs from commensal DNA  

PubMed Central

The microbiota contributes to the induction of both effector and regulatory responses in the gastrointestinal tract. However, the mechanisms controlling these distinct properties remain poorly understood. We previously showed that commensal DNA promotes intestinal immunity. Here, we find that the capacity of bacterial DNA to stimulate immune responses is species specific and correlated with the frequency of motifs known to exert immunosuppressive function. In particular, we show that the DNA of Lactobacillus species, including various probiotics, are enriched in suppressive motifs able to inhibit lamina propria DC activation. In addition, immunosuppressive oligonucleotides sustain Treg cell conversion during inflammation and limit pathogen-induced immunopathology and colitis. Altogether, our findings identify DNA suppressive motifs as a molecular ligand expressed by commensals and support the idea that a balance between stimulatory and regulatory DNA motifs contributes to the induction of controlled immune responses in the GI tract and gut immune homeostasis. Further, our findings suggest that the endogenous regulatory capacity of DNA motifs enriched in some commensal bacteria could be exploited for therapeutic purposes.

Bouladoux, N.; Hall, J.A.; Grainger, J. R.; dos Santos, L. M.; Kann, M.G.; Nagarajan, V.; Verthelyi, D.; Belkaid, Y.

2012-01-01

307

Suppression of autoimmune retinal inflammation by an antiangiogenic drug.  

PubMed

Chronic and recurrent uveitis account for approximately 10% of legal blindness in the western world. Autoimmune uveitis is driven by activated CD4(+) T cells that differentiate into effector T helper cells (Th1, Th2, and Th17) which release proinflammatory cytokines that damage the retina. In this study we investigated the effect of the methionine aminopeptidase 2 (MetAP2) inhibitor, Lodamin, on T cell activation and differentiation. MetAp2 is an enzyme which regulates cellular protein synthesis and is highly expressed in T cells. Lodamin was found to suppress T cell receptor (TCR) mediated T cell proliferation and reduced the production of Th1 and Th17 cells. Further, Lodamin suppressed overall inflammation in the mouse model of experimental autoimmune uveitis (EAU) by a six fold. This effect was attributed in part to a reduction in retinal proinflammatory cytokines, down regulation of MetAP2 expression in purified lymph node CD4(+) T cells, and a general normalization of the systemic immune reaction. PMID:23785488

Yoshimura, Takeru; Benny, Ofra; Bazinet, Lauren; D'Amato, Robert J

2013-06-13

308

Tranquilizer effects on conditioned suppression  

Microsoft Academic Search

The effects of chlorpromazine, meprobamate and reserpine on animal experimental conditioned suppression are reported. Over a wide dose range neither chlorpromazine nor meprobamate increased responding for positive reinforcement during a shock-paired stimulus. Reserpine given chronically did increase responding during shock-paired stimuli. The motor depressant effect of reserpine, at suppression attenuating doses, is most probably related to the response measure used

Oakley S. Ray

1964-01-01

309

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

310

An alternative to thought suppression?  

PubMed

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. PMID:22963421

Boice, Robert

2012-09-01

311

Salmonella Phage ST64B Encodes a Member of the SseK\\/NleB Effector Family  

Microsoft Academic Search

Salmonella enterica is a species of bacteria that is a major cause of enteritis across the globe, while certain serovars cause typhoid, a more serious disease associated with a significant mortality rate. Type III secreted effectors are major contributors to the pathogenesis of Salmonella infections. Genes encoding effectors are acquired via horizontal gene transfer, and a subset are encoded within

Nat F. Brown; Brian K. Coombes; Jenna L. Bishop; Mark E. Wickham; Michael J. Lowden; Ohad Gal-Mor; David L. Goode; Erin C. Boyle; Kristy L. Sanderson; B. Brett Finlay

2011-01-01

312

Ex vivo characterization of human CD8+ T subsets with distinct replicative history and partial effector functions.  

PubMed

After antigenic challenge, naive T lymphocytes enter a program of proliferation and differentiation during the course of which they acquire effector functions and may ultimately become memory cells. In humans, the pathways of effector and memory T-cell differentiation remain poorly defined. Here we describe the properties of 2 CD8+ T-lymphocyte subsets, RA+CCR7-27+28+ and RA+CCR7-27+28-, in human peripheral blood. These cells display phenotypic and functional features that are intermediate between naive and effector T cells. Like naive T lymphocytes, both subsets show relatively long telomeres. However, unlike the naive population, these T cells exhibit reduced levels of T-cell receptor excision circles (TRECs), indicating they have undergone additional rounds of in vivo cell division. Furthermore, we show that they also share effector-type properties. At equivalent in vivo replicative history, the 2 subsets express high levels of Fas/CD95 and CD11a, as well as increasing levels of effector mediators such as granzyme B, perforin, interferon gamma, and tumor necrosis factor alpha. Both display partial ex vivo cytolytic activity and can be found among cytomegalovirus-specific cytolytic T cells. Taken together, our data point to the presence of T cells with intermediate effector-like functions and suggest that these subsets consist of T lymphocytes that are evolving toward a more differentiated effector or effector-memory stage. PMID:12750165

Rufer, Nathalie; Zippelius, Alfred; Batard, Pascal; Pittet, Mikael J; Kurth, Isabel; Corthesy, Patricia; Cerottini, Jean-Charles; Leyvraz, Serge; Roosnek, Eddy; Nabholz, Markus; Romero, Pedro

2003-05-15

313

Strong TCR Signaling, TLR Ligands, and Cytokine Redundancies Ensure Robust Development of Type 1 Effector T Cells1  

Microsoft Academic Search

T cell effector function is a central mechanism of adaptive immunity, and accordingly, protection of the host against pathogens. One of the primary effector molecules produced by T cells in response to such pathogens is the cytokine, IFN-. Although the signaling pathways associated with the production of IFN- are well established, disparate in vivo and in vitro results indicate that

Chiara Nembrini; Brian Abel; Manfred Kopf; Benjamin J. Marsland

314

TRANSGENIC EXPRESSION OF THE ERWINIA AMYLOVORA (FIRE BLIGHT) EFFECTOR PROTEIN EOP1 SUPRESSES HOST BASAL DEFENSE MECHANISMS IN MALUS (APPLE)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Erwinia amylovora (Ea) is the causative agent of fire blight, a devastating disease of apple and pear. Like many other plant and animal bacterial pathogens Ea utilizes a type three secretion system (TTSS) to deliver effector proteins into plant host cells. Once inside the host cell, effector protei...

315

Isolation of a Temperate Bacteriophage Encoding the Type III Effector Protein SopE from an Epidemic Salmonella typhimurium Strain  

Microsoft Academic Search

Salmonella typhimurium employs the specialized type III secretion system encoded in pathogenicity island 1 (SPI1) to translocate effector proteins into host cells and to modulate host cell signal transduction. The SPI1 type III system and the effector proteins are conserved among all salmonellae and are thought to be acquired by horizontal gene transfer. The genetic mechanisms mediating this horizontal transfer

Susanne Mirold; Wolfgang Rabsch; Manfred Rohde; Silke Stender; Helmut Tschape; Holger Russmann; Emeka Igwe; Wolf-Dietrich Hardt

1999-01-01

316

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

2013-07-22

317

A functional post-genomics approach to dissect SnToxA effector mode-of-action in wheat  

Technology Transfer Automated Retrieval System (TEKTRAN)

It has now been established that the wheat pathogen Stagonospora nodorum causes disease on wheat in an inverse gene-for-gene manner through the interaction of pathogen effector proteins and corresponding dominant susceptibility host genes. One such effector, SnToxA, interacts with the Tsn1 gene to c...

318

The chemically inducible expression of Erwinia amylovora bacterial effectors EopB1 and HopCEa in apple  

Technology Transfer Automated Retrieval System (TEKTRAN)

Erwinia amylovora, the causal agent of fire blight disease, utilizes a type three secretion system to deliver effector proteins into plant host cells. To investigate the role of individual bacterial effector proteins, we have engineered an apple host that transgenically expresses the bacterial effe...

319

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

320

Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.  

PubMed

Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints. PMID:21326234

Rouxel, Thierry; Grandaubert, Jonathan; Hane, James K; Hoede, Claire; van de Wouw, Angela P; Couloux, Arnaud; Dominguez, Victoria; Anthouard, Véronique; Bally, Pascal; Bourras, Salim; Cozijnsen, Anton J; Ciuffetti, Lynda M; Degrave, Alexandre; Dilmaghani, Azita; Duret, Laurent; Fudal, Isabelle; Goodwin, Stephen B; Gout, Lilian; Glaser, Nicolas; Linglin, Juliette; Kema, Gert H J; Lapalu, Nicolas; Lawrence, Christopher B; May, Kim; Meyer, Michel; Ollivier, Bénédicte; Poulain, Julie; Schoch, Conrad L; Simon, Adeline; Spatafora, Joseph W; Stachowiak, Anna; Turgeon, B Gillian; Tyler, Brett M; Vincent, Delphine; Weissenbach, Jean; Amselem, Joëlle; Quesneville, Hadi; Oliver, Richard P; Wincker, Patrick; Balesdent, Marie-Hélène; Howlett, Barbara J

2011-02-15

321

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

2012-12-03

322

Hyaloperonospora arabidopsidis ATR1 effector is a repeat protein with distributed recognition surfaces  

PubMed Central

The in planta association of the Hyaloperonospora arabidopsidis effector ATR1 with the cognate Arabidopsis thaliana RPP1 immune receptor activates a disease-resistance signaling pathway that inhibits pathogen growth. To define the molecular events specifying effector recognition by RPP1, we determined the crystal structure of ATR1 and assayed in planta the effects of surface polymorphisms that are critical to activating plant immunity. ATR1 adopts an elongated, all-helical, two-domain, seahorse-like structure with an overall architecture unlike any previously described fold. Structural comparisons highlight a tandemly duplicated, five-helix motif in the C-terminal domain that creates a structural framework for rapid diversification. Identification and mapping of critical recognition sites suggest that ATR1 detection by the RPP1 resistance protein is mediated by several distinct protein surfaces that allow the effectors to escape recognition through diverse surface polymorphisms. ATR1 gain-of-recognition mutants demonstrate that multiple amino acid substitutions are necessary for recognition and that surface polymorphisms exert additive effects. These results suggest that ATR1 is a modular repeat protein belonging to an ancient family of oomycete effectors that rapidly evolves to escape host detection and adopt diverse virulence functions.

Chou, Seemay; Krasileva, Ksenia V.; Holton, James M.; Steinbrenner, Adam D.; Alber, Tom; Staskawicz, Brian J.

2011-01-01

323

Effects of altered auditory feedback across effector systems: production of melodies by keyboard and singing.  

PubMed

We report an experiment that tested whether effects of altered auditory feedback (AAF) during piano performance differ from its effects during singing. These effector systems differ with respect to the mapping between motor gestures and pitch content of auditory feedback. Whereas this action-effect mapping is highly reliable during phonation in any vocal motor task (singing or speaking), mapping between finger movements and pitch occurs only in limited situations, such as piano playing. Effects of AAF in both tasks replicated results previously found for keyboard performance (Pfordresher, 2003), in that asynchronous (delayed) feedback slowed timing whereas alterations to feedback pitch increased error rates, and the effect of asynchronous feedback was similar in magnitude across tasks. However, manipulations of feedback pitch had larger effects on singing than on keyboard production, suggesting effector-specific differences in sensitivity to action-effect mapping with respect to feedback content. These results support the view that disruption from AAF is based on abstract, effector independent, response-effect associations but that the strength of associations differs across effector systems. PMID:22100135

Pfordresher, Peter Q; Mantell, James T

2011-11-17

324

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

325

Activation-induced cell death limits effector function of CD4 tumor-specific T cells.  

PubMed

A number of studies have documented a critical role for tumor-specific CD4(+) cells in the augmentation of immunotherapeutic effector mechanisms. However, in the context of an extensive tumor burden, chronic stimulation of such CD4(+) T cells often leads to the up-regulation of both Fas and Fas ligand, and coexpression of these molecules can potentially result in activation-induced cell death and the subsequent loss of effector activity. To evaluate the importance of T cell persistence in an experimental model of immunotherapy, we used DO11 Th1 cells from wild-type, Fas-deficient, and Fas ligand-deficient mice as effector populations specific for a model tumor Ag consisting of an OVA-derived transmembrane fusion protein. We found that the prolonged survival of Fas-deficient DO11 Th1 cells led to a more sustained tumor-specific response both in vitro and in vivo. Importantly, both Fas- and Fas ligand-deficient Th1 cells delayed tumor growth and cause regression of established tumors more effectively than wild-type Th1 cells, indicating that resistance to activation-induced cell death significantly enhances T cell effector activity. PMID:15153474

Saff, Rebecca R; Spanjaard, Elena S; Hohlbaum, Andreas M; Marshak-Rothstein, Ann

2004-06-01

326

Patient adaptive control of end-effector based gait rehabilitation devices using a haptic control framework  

Microsoft Academic Search

Robot assisted training has proven beneficial as an extension of conventional therapy to improve rehabilita- tion outcome. Further facilitation of this positive impact is expected from the application of cooperative control algorithms to increase the patient's contribution to the training effort according to his level of ability. This paper presents an approach for cooperative training for end-effector based gait rehabilitation

Sami Hussein; Jorg Kruger

2011-01-01

327

A portable sensorized micro end-effector for operating in biomedical test-benches  

Microsoft Academic Search

This paper is focused on a portable sensorized micro end-effector purposely designed for operating in biomedical test-benches. The gripper, previously designed and fabricated in various materials exploiting different technologies, has been devised to perform tasks of micromanipulation and characterization of biological tissues once integrated into the workstation developed in the authors' lab. The last model of the gripper prototype has

A. Eisinberg; I. Izzo; P. Valdastri; A. Menciassi; P. Dario

2003-01-01

328

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

329

Structure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptake  

PubMed Central

A binary complex of the ammonia channel Amt1 from Methanococcus jannaschii and its cognate PII signalling protein GlnK1 has been produced and characterized. Complex formation is prevented specifically by the effector molecules Mg-ATP and 2-ketoglutarate. Single-particle electron microscopy of the complex shows that GlnK1 binds on the cytoplasmic side of Amt1. Three high-resolution X-ray structures of GlnK1 indicate that the functionally important T-loop has an extended, flexible conformation in the absence of Mg-ATP, but assumes a compact, tightly folded conformation upon Mg-ATP binding, which in turn creates a 2-ketoglutarate-binding site. We propose a regulatory mechanism by which nitrogen uptake is controlled by the binding of both effector molecules to GlnK1. At normal effector levels, a 2-ketoglutarate molecule binding at the apex of the compact T-loop would prevent complex formation, ensuring uninhibited ammonia uptake. At low levels of Mg-ATP, the extended loops would seal the ammonia channels in the complex. Binding of both effector molecules to PII signalling proteins may thus represent an effective feedback mechanism for regulating ammonium uptake through the membrane.

Yildiz, Ozkan; Kalthoff, Christoph; Raunser, Stefan; Kuhlbrandt, Werner

2007-01-01

330

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

331

?c deficiency precludes CD8+ T cell memory despite formation of potent T cell effectors  

PubMed Central

Several cytokines (including IL-2, IL-7, IL-15, and IL-21) that signal through receptors sharing the common ? chain (?c) are critical for the generation and peripheral homeostasis of naive and memory T cells. Recently, we demonstrated that effector functions fail to develop in CD4+ T cells that differentiate in the absence of ?c. To assess the role of ?c cytokines in cell-fate decisions that condition effector versus memory CD8+ T cell generation, we compared the response of CD8+ T cells from ?c+ or ?c? P14 TCR transgenic mice after challenge with lymphocytic choriomeningitis virus. The intrinsic IL-7-dependent survival defect of ?c? naive CD8+ T cells was corrected by transgenic expression of human Bcl-2. We demonstrated that although ?c-dependent signals are dispensable for the initial expansion and the acquisition of cytotoxic functions following antigenic stimulation, they condition the terminal proliferation and differentiation of CD8+ effector T cells (i.e., KLRG1high CD127low short-lived effector T cells) via the transcription factor, T-bet. Moreover, the ?c-dependent signals that are critical for memory T cell formation are not rescued by Bcl2 overexpression. Together, these data reveal an unexpected divergence in the requirement for ?c cytokines in the differentiation of CD4+ versus CD8+ cytotoxic T lymphocytes.

Decaluwe, Helene; Taillardet, Morgan; Corcuff, Erwan; Munitic, Ivana; Law, Helen K. W.; Rocha, Benedita; Riviere, Yves; Di Santo, James P.

2010-01-01

332

Action of the p53 Effector, p21, on its Targets: Cyclin-CDK & PCNA.  

National Technical Information Service (NTIS)

Our aim is to dissect the interactions of p21 (a downstream effector of the tumor suppressor protein p53) with its targets, cyclin-cdks and PCNA. In year 2 we have focused on the cyclin-cdks. We have quantitated the contribution of the cyclin-cdks binding...

A. Dutta

1999-01-01

333

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.

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

334

The role of natural killer cells in tumor control—effectors and regulators of adaptive immunity  

Microsoft Academic Search

Natural killer (NK) cells are the primary effector cells of the innate immune system and have a well-established role in tumor rejection in a variety of spontaneous and induced cancer models. NK cell function is regulated by a complex balance of inhibitory and activating signals that allow them to selectively target and kill cells that display an abnormal pattern of

Morgan E. Wallace; Mark J. Smyth

2005-01-01

335

Regulation of Type III Secretion Hierarchy of Translocators and Effectors in Attaching and Effacing Bacterial Pathogens  

Microsoft Academic Search

Human enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC), and the mouse pathogen Citrobacter rodentium (CR) belong to the family of attaching and effacing (A\\/E) bacterial pathogens. They possess the locus of enterocyte effacement (LEE) pathogenicity island, which encodes a type III secretion system. These pathogens secrete a number of proteins into culture media, including type III effector proteins and

Wanyin Deng; Yuling Li; Philip R. Hardwidge; Elizabeth A. Frey; Richard A. Pfuetzner; Sansan Lee; Samantha Gruenheid; Natalie C. J. Strynakda; Jose L. Puente; B. B. Finlay

2005-01-01

336

IP10 Is Critical for Effector T Cell Trafficking and Host Survival in Toxoplasma gondii Infection  

Microsoft Academic Search

The generation of an adaptive immune response against intracellular pathogens requires the recruitment of effector T cells to sites of infection. Here we show that the chemokine IP-10, a specific chemoattractant for activated T cells, controls this process in mice naturally infected with Toxoplasma gondii. Neutralization of IP-10 in infected mice inhibited the massive influx of T cells into tissues

Imtiaz A Khan; James A MacLean; Frederick S Lee; Lori Casciotti; Elliot DeHaan; Joseph D Schwartzman; Andrew D Luster

2000-01-01

337

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.

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

338

Visuomotor and Audiomotor Processing in Continuous Force Production of Oral and Manual Effectors  

Microsoft Academic Search

The authors examined force control in oral and manual effectors as a function of sensory feedback (i.e., visual and auditory). Participants produced constant isometric force via index finger flexion and lower lip elevation to 2 force levels (10% and 20% maximal voluntary contraction) and received either online visual or online auditory feedback. Mean, standard deviation, and coefficient of variation of

Edward Ofori; Torrey M. J. Loucks; Jacob J. Sosnoff

2012-01-01

339

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

2013-02-28

340

The Effect of Trophoblasts on T Lymphocytes: Possible Regulatory Effector Molecules - A Proteomic Analysis  

Microsoft Academic Search

Background\\/Aims: Tolerance of T lymphocytes at the feto-maternal interface is necessary to sustain normal pregnancy. The present investigation aimed to observe the regulatory effects on T lymphocytes by human trophoblasts and to explore possible effector molecules. Methods: Conditioned media was made by trophoblast culture or villous explant culture for T lymphocyte proliferation and proteomic analysis. Lymphocyte proliferation was tested by

Minyue Dong; Guolian Ding; Jun Zhou; Hanzhi Wang; Yi Zhao; Hefeng Huang

2008-01-01

341

T Cell Affinity Regulates Asymmetric Division, Effector Cell Differentiation, and Tissue Pathology  

PubMed Central

SUMMARY The strength of interactions between T cell receptors and the peptide-major histocompatibility complex (pMHC) directly modulates T cell fitness, clonal expansion, and acquisition of effector properties. Here we show that asymmetric T cell division is an important mechanistic link between increased signal strength, effector differentiation, and the ability to induce tissue pathology. Recognition of pMHC above a threshold affinity drove responding T cells into asymmetric cell division. The ensuing proximal daughters underwent extensive division and differentiated into short-lived effector cells expressing the integrin VLA-4, allowing the activated T cell to infiltrate and mediate destruction of peripheral target tissues. In contrast, T cells activated by below-threshold antigens underwent symmetric division, leading to abortive clonal expansion and failure to fully differentiate into tissue-infiltrating effector cells. Antigen affinity and asymmetric division are important factors that regulate fate specification in CD8+ T cells and predict the potential of a self-reactive T cell to mediate tissue pathology.

King, Carolyn G.; Koehli, Sabrina; Hausmann, Barbara; Schmaler, Mathias; Zehn, Dietmar; Palmer, Ed

2013-01-01

342

Development and testing of nano robot end effector for cell electrophysiology and elastography studies  

Microsoft Academic Search

Electrophysiology and elastrography provide significant information in biological and biomedical studies. Conventional atomic force microscopes (AFMs) have been used for the mechanical characterization of living cells, but they lack the capability to measure the electrical properties of biological cells and tissues. In this work, a novel nano robot end effector has been developed to perform multidimensional measurement of cells. The

King Wai Chiu Lai; Angelo Gaitas; Ning Xi; Ruiguo Yang; Carmen Kar Man Fung

2011-01-01

343

Cytokines, Signaling Pathways, and Effector Molecules Required for the Control of Leishmania (Viannia) braziliensis in Mice  

Microsoft Academic Search

Cutaneous leishmaniasis is caused by protozoan parasites of the genus Leishmania. The mechanisms of pathogen control have been established primarily in the mouse model of Leishmania major infection, but they might not hold true for other Leishmania species associated with cutaneous disease. Here, we analyzed the role of cytokines, signaling components, and effector molecules in the control of New World

F. Janaina Soares Rocha; Ulrike Schleicher; Jochen Mattner; Gottfried Alber; Christian Bogdan

2007-01-01

344

An adaptive scheme for compensation of loss of effectiveness of flight control effectors  

Microsoft Academic Search

In this paper we present two stable adaptive tracking control algorithms for compensation of loss of effectiveness of control effectors in flight control applications. The overall approach is based on suitable failure parameterization, control law and adaptive algorithm design, and Lyapunov analysis of the properties of the overall system. The proposed adaptive algorithms are based on parameter-adaptive and variable-structure control

Jovan D. BoSkoviC; Raman K. Mehra

2001-01-01

345

Adaptive connection to the world through self-organizing sensors and effectors  

Microsoft Academic Search

The realm of devices composed of adaptive sensing, computing, and effecting elements is surveyed, and contemporary devices are categorized accordingly. A new class of adaptive devices, those which adaptively construct their sensors and effectors, is presented. Such complement those which perform adaptive computations and could be used for adaptively constructing appropriate feature and action primitives for connectionist devices, thereby determining

Peter Cariani

1990-01-01

346

Modulation of innate immune responses by Yersinia type III secretion system translocators and effectors.  

PubMed

The innate immune system of mammals responds to microbial infection through detection of conserved molecular determinants called 'pathogen-associated molecular patterns' (PAMPs). Pathogens use virulence factors to counteract PAMP-directed responses. The innate immune system can in turn recognize signals generated by virulence factors, allowing for a heightened response to dangerous pathogens. Many Gram-negative bacterial pathogens encode type III secretion systems (T3SSs) that translocate effector proteins, subvert PAMP-directed responses and are critical for infection. A plasmid-encoded T3SS in the human-pathogenic Yersinia species translocates seven effectors into infected host cells. Delivery of effectors by the T3SS requires plasma membrane insertion of two translocators, which are thought to form a channel called a translocon. Studies of the Yersinia?T3SS have provided key advances in our understanding of how innate immune responses are generated by perturbations in plasma membrane and other signals that result from translocon insertion. Additionally, studies in this system revealed that effectors function to inhibit innateimmune responses resulting from insertion of translocons into plasma membrane. Here, we review these advances with the goal of providing insight into how a T3SS can activate and inhibit innate immune responses, allowing a virulent pathogen to bypass host defences. PMID:23834311

Bliska, James B; Wang, Xiaoying; Viboud, Gloria I; Brodsky, Igor E

2013-07-29

347

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

348

DIFFERENTIAL REQUIREMENT FOR CD18 IN T-HELPER EFFECTOR HOMING  

Technology Transfer Automated Retrieval System (TEKTRAN)

To understand the integrin requirements of T-helper (TH) effector subsets, we investigated the contribution of CD18 (beta-2 integrin) to TH1 and TH2 function in vitro and in relevant disease models. CD18-deficient (Itgb2-/-) T cells showed largely normal in vitro function. Compared with wild-type mi...

349

Heterotropic effectors exert more significant strain on monoligated than on unligated hemoglobin.  

PubMed Central

The effect of allosteric effectors, such as inositol hexakisphosphate and/or bezafibrate, has been investigated on the unliganded human adult hemoglobin both spectroscopically (employing electronic absorption, circular dichroism, resonance Raman, and x-ray absorption near-edge spectroscopies) and functionally (following the kinetics of the first CO binding step up to a final 4% ligand saturation degree). All data indicate that the unliganded T-state is not perturbed by the interaction with either one or both effectors, suggesting that their functional influence is only exerted when a ligand molecule is bound to the heme. This is confirmed by the observation that CO dissociation from partially liganded hemoglobin ( effector, and the effect is enhanced whenever the two effectors are simultaneously present. Altogether, these data are a direct demonstration of the occurrence of a strain induced by the presence of a ligand molecule bound to the heme, and for the first time there is a clear indication that the expression of the functional heterotropic effect by these non-heme ligands requires this strain, which is not present in the unliganded molecule.

Coletta, M; Angeletti, M; Ascone, I; Boumis, G; Castellano, A C; Dell'Ariccia, M; Della Longa, S; De Sanctis, G; Priori, A M; Santucci, R; Feis, A; Amiconi, G

1999-01-01

350

Notch controls generation and function of human effector CD8+ T cells.  

PubMed

The generation of effector CD8(+) T cells with lytic capacity is crucial for tumor control. Dendritic cells (DCs) provide important signals to promote naive CD8(+) T cell priming and activation of effector T cells. Here, we report that the Notch pathway has an important role in both these processes in human CD8(+) T cells. Activated monocyte-derived DCs express Notch ligands Jagged1 and Delta-like4, whereas naive CD8(+) T cells express Notch2. The role for Notch signaling in CD8(+) T cell priming was determined using an ex-vivo model system in which tumor antigen-specific primary CD8(+) T cell responses were measured. Inhibition of Notch using ?-secretase inhibitors or soluble Delta-like4-Fc during activation reduced expansion of antigen-specific CD8(+) T cells, which was mirrored by decreased frequencies of interferon (IFN)?-, tumor necrosis factor-?-, and granzymeB-producing CD8(+) T cells. Moreover, T cells primed when Notch signaling was prevented are functionally low-avidity T cells. In addition, Notch partially regulates established effector T cell function. Activation-induced Notch signaling is needed for IFN? release but not for cytolytic activity. These data indicate that Notch signaling controls human CD8(+) T cell priming and also influences effector T cell functions. This may provide important information for designing new immunotherapies for treatment of cancer. PMID:23380742

Kuijk, Loes M; Verstege, Marleen I; Rekers, Niels V; Bruijns, Sven C; Hooijberg, Erik; Roep, Bart O; de Gruijl, Tanja D; van Kooyk, Yvette; Unger, Wendy W J

2013-02-04

351

Endogenous effectors of human liver glycogen phosphorylase modulate effects of indole-site inhibitors.  

PubMed

Phosphorylase is regulated by a number of small-molecular-weight effectors that bind to three sites on the enzyme. Recently, a fourth site referred to as the indole-inhibitor site has been identified. Synthetic compounds bind to the site and inhibit activity. However, the effects of these compounds in the presence of other endogenous effectors are unknown. We have determined the effects of four indole derivative glycogen phosphorylase inhibitors (GPI) on recombinant human liver glycogen phosphorylase a activity. The GPIs tested were all potent inhibitors. However, the endogenous inhibitors (glucose, ADP, ATP, fructose 1-phosphate, glucose 6-phosphate, UDP-glucose) and the activator (AMP) markedly reduced the inhibitory effect of GPIs. Consistent with these in vitro findings, the IC50 for the inhibition of glycogenolysis in cells and the liver drug concentration associated with glucose-lowering activity in diabetic ob/ob mice in vivo were also significantly higher than those determined in in vitro enzyme assays. The inhibitory effect of indole-site effectors is modulated by endogenous small-molecular-weight effectors of phosphorylase a activity. However, at higher concentrations (10-30 microM), the GPI effect was dominant and resulted in inhibition of phosphorylase a activity irrespective of the presence or absence of the other modulators of the enzyme. PMID:15797986

Ercan-Fang, Nacide; Taylor, Miriam R; Treadway, Judith L; Levy, Carolyn B; Genereux, Paul E; Gibbs, E Michael; Rath, Virginia L; Kwon, Younggil; Gannon, Mary C; Nuttall, Frank Q

2005-03-29

352

Non-neutral evolution in non-LEE-encoded type III effectors of attaching and effacing Escherichia coli.  

PubMed

Attaching and effacing Escherichia coli (AEEC) employ type III secretion system (T3SS) to secrete effector proteins into host cells and regulate their function. Here we have investigated T3SS genes of AEEC for non-neutral evolution. Our analysis revealed non-neutral evolution in three genes (nleE1, nleB2 and nleD) which encode effector proteins. These genes are located outside the locus of enterocyte effacement (LEE). In general, non-LEE effector genes show greater deviation from neutral evolution than LEE effector genes. These results suggest that effector genes located outside LEE are under greater selection pressure than those present in LEE. PMID:23142035

Eswarappa, Sandeepa M; Janice, Jessin; Balasundaram, Sudhagar V; Chakravortty, Dipshikha

2012-11-07

353

Pro-inflammatory effector Th cells transmigrate through anti-inflammatory environments into the murine fetus.  

PubMed

The presence of maternal DNA or even maternal cells within the offspring (microchimerism) has been reported for many fetal tissues, including the liver, heart, and spleen. Microchimerism is believed to be involved in the pathogenesis of autoimmune diseases; however, the cellular origin of this phenomenon remains unknown. Here, we determined whether differentiated T lymphocytes could transmigrate through the immunosuppressive environment of the placenta to reach the fetus. In vitro-differentiated effector/memory Th1 and Th17 cells from OVA???????-specific TCR(tg) T cells of OT-II mice were adoptively transferred (i.v.) into the tail veins of pregnant Ly5.1 mice at d15 and d19 of gestation. Mice were then sacrificed 40 h after adoptive cell transfer. Using radioactive labeling of T cells with sodium chromate [Cr?¹] prior to adoptive transfer, we observed that homing of pro-inflammatory Th cells was equally efficient in both pregnant and non-pregnant mice. Transmigration of Th1- and Th17-like cells through the highly immunosuppressive environment of the placenta into the fetus was significantly enhanced in experimental mice compared to control mice (P < 0.0001). In addition, a substantial amount of effector Th cells accumulated in the placenta. Finally, we found that treatment with Pertussis Toxin resulted in a 3-fold increase in the transmigration of effector Th17 cells into the fetus (P < 0.0001). When pro-inflammatory Th1-or Th17-like cells were injected into syngeneic mothers, almost all of the fetuses analyzed exhibited radioactivity, suggesting that transmigration of effector T cells occurs frequently. Our results suggest the possibility of novel roles for these maternal effector cells in the pathogenesis or reduction of disease. PMID:22093381

Wienecke, J; Hebel, K; Hegel, K J; Pierau, M; Brune, T; Reinhold, D; Pethe, A; Brunner-Weinzierl, M C

2011-11-16

354

The E. coli Effector Protein NleF Is a Caspase Inhibitor  

PubMed Central

Enterohemorrhagic and enteropathogenic E. coli (EHEC and EPEC) can cause severe and potentially life-threatening infections. Their pathogenicity is mediated by at least 40 effector proteins which they inject into their host cells by a type-III secretion system leading to the subversion of several cellular pathways. However, the molecular function of several effectors remains unknown, even though they contribute to virulence. Here we show that one of them, NleF, binds to caspase-4, -8, and -9 in yeast two-hybrid, LUMIER, and direct interaction assays. NleF inhibits the catalytic activity of the caspases in vitro and in cell lysate and prevents apoptosis in HeLa and Caco-2 cells. We have solved the crystal structure of the caspase-9/NleF complex which shows that NleF uses a novel mode of caspase inhibition, involving the insertion of the carboxy-terminus of NleF into the active site of the protease. In conformance with our structural model, mutagenized NleF with truncated or elongated carboxy-termini revealed a complete loss in caspase binding and apoptosis inhibition. Evasion of apoptosis helps pathogenic E. coli and other pathogens to take over the host cell by counteracting the cell’s ability to self-destruct upon infection. Recently, two other effector proteins, namely NleD and NleH, were shown to interfere with apoptosis. Even though NleF is not the only effector protein capable of apoptosis inhibition, direct inhibition of caspases by bacterial effectors has not been reported to date. Also unique so far is its mode of inhibition that resembles the one obtained for synthetic peptide-type inhibitors and as such deviates substantially from previously reported caspase-9 inhibitors such as the BIR3 domain of XIAP.

Blasche, Sonja; Mortl, Mario; Steuber, Holger; Siszler, Gabriella; Nisa, Shahista; Schwarz, Frank; Lavrik, Inna; Gronewold, Thomas M. A.; Maskos, Klaus; Donnenberg, Michael S.; Ullmann, Dirk; Uetz, Peter; Kogl, Manfred

2013-01-01

355

Wsp1 Is Downstream of Cin1 and Regulates Vesicle Transport and Actin Cytoskeleton as an Effector of Cdc42 and Rac1 in Cryptococcus neoformans  

PubMed Central

Human Wiskott-Aldrich syndrome protein (WASP) is a scaffold linking upstream signals to the actin cytoskeleton. In response to intersectin ITSN1 and Rho GTPase Cdc42, WASP activates the Arp2/3 complex to promote actin polymerization. The human pathogen Cryptococcus neoformans contains the ITSN1 homolog Cin1 and the WASP homolog Wsp1, which share more homology with human proteins than those of other fungi. Here we demonstrate that Cin1, Cdc42/Rac1, and Wsp1 function in an effector pathway similar to that of mammalian models. In the cin1 mutant, expression of the autoactivated Wsp1-B-GBD allele partially suppressed the mutant defect in endocytosis, and expression of the constitutively active CDC42Q61L allele restored normal actin cytoskeleton structures. Similar phenotypic suppression can be obtained by the expression of a Cdc42-green fluorescent protein (GFP)-Wsp1 fusion protein. In addition, Rac1, which was found to exhibit a role in early endocytosis, activates Wsp1 to regulate vacuole fusion. Rac1 interacted with Wsp1 and depended on Wsp1 for its vacuolar membrane localization. Expression of the Wsp1-B-GBD allele restored vacuolar membrane fusion in the rac1 mutant. Collectively, our studies suggest novel ways in which this pathogenic fungus has adapted conserved signaling pathways to control vesicle transport and actin organization, likely benefiting survival within infected hosts.

Shen, Gui; Zhou, Erxun; Alspaugh, J. Andrew

2012-01-01

356

Characterization of the Conditioned Medium from Amniotic Membrane Cells: Prostaglandins as Key Effectors of Its Immunomodulatory Activity  

PubMed Central

We previously demonstrated that cells isolated from the mesenchymal region of the human amniotic membrane (human amniotic mesenchymal tissue cells, hAMTC) possess immunoregulatory roles, such as inhibition of lymphocyte proliferation and cytokine production, and suppression of generation and maturation of monocyte-derived dendritic cells, as reported for MSC from other sources. The precise factors and mechanisms responsible for the immunoregulatory roles of hAMTC remain unknown. In this study, we aimed to identify the soluble factors released by hAMTC and responsible for the anti-proliferative effect on lymphocytes, and the mechanisms underlying their actions, in vitro. Conditioned medium (CM) was prepared under routine culture conditions from hAMTC (CM-hAMTC) and also from fragments of the whole human amniotic membrane (CM-hAM). We analyzed the thermostability, chemical nature, and the molecular weight of the factors likely responsible for the anti-proliferative effects. We also evaluated the participation of cytokines known to be involved in the immunomodulatory actions of MSC from other sources, and attempted to block different synthetic pathways. We demonstrate that the inhibitory factors are temperature-stable, have a small molecular weight, and are likely of a non-proteinaceous nature. Only inhibition of cyclooxygenase pathway partially reverted the anti-proliferative effect, suggesting prostaglandins as key effector molecules. Factors previously documented to take part in the inhibitory effects of MSCs from other sources (HGF, TGF-?, NO and IDO) were not involved. Furthermore, we prove for the first time that the anti-proliferative effect is intrinsic to the amniotic membrane and cells derived thereof, since it is manifested in the absence of stimulating culture conditions, as opposed to MSC derived from the bone marrow, which possess an anti-proliferative ability only when cultured in the presence of activating stimuli. Finally, we show that the amniotic membrane could be an interesting source of soluble factors, without referring to extensive cell preparation.

Rossi, Daniele; Pianta, Stefano; Magatti, Marta; Sedlmayr, Peter; Parolini, Ornella

2012-01-01

357

Expansion of Effector Memory Regulatory T-cells Represents A Novel Prognostic Factor in Lower Risk Myelodysplastic Syndrome  

PubMed Central

Myleodysplastic syndromes (MDS) are premalignant diseases characterized by cytopenias, myeloid dysplasia, immune dysregulation with association to autoimmunity, and variable risk for acute myeloid leukemia (AML) transformation. Studies of Forkhead-box P3 (FoxP3)+ regulatory T-cells (Tregs) indicate that the number and/or activation state may influence cancer progression in these patients. Focusing on patients with a lower-risk for leukemia transformation, 18 (34.6%) of 52 patients studied displayed an altered Treg compartment compared to age-matched controls. Delineation of unique Treg subsets revealed that an increase in the absolute number of CD4(+)FoxP3(+)CD25(+)CD127(low)CD45RA(?)CD27(?) Tregs (effector memory Tregs; TregEM) was significantly associated with anemia (p=0.046), reduced hemoglobin (p=0.038), and blast counts ?5% (p=0.006). In healthy donors, this TregEM population constitutes only 2% of all Tregs (1–6 Treg cells/?l) in peripheral blood, but when isolated, exhibit greater suppressive activity in vitro. With a median follow-up of 3.1 years (range-2.7 to 4.9) from sample acquisition, increased numbers of TregEM cells proved to have independent prognostic importance in survival estimates suggesting that enumeration of this Treg subset may be a more reliable indicator of immunological escape than FoxP3+ T-cells as a whole. Based on multivariate analyses, TregEM impacted survival independently from myeloblast characteristics, cytopenias, karyotype and comorbidities. Based on these findings, TregEM cell expansion may be synonymous with human Treg activation and indicate microenvironmental changes conducive to transformation in MDS.

Mailloux, Adam W; Sugimori, Chiharu; Komrokji, Rami S.; Yang, Lili; Maciejewski, Jaroslaw P.; Sekeres, Mikkael A.; Paquette, Ronald; Loughran, Thomas P.; List, Alan F.; Epling-Burnette, P.K.

2012-01-01

358

Effector role of neonatal hepatic CD8+ lymphocytes in epithelial injury and autoimmunity in experimental biliary atresia  

PubMed Central

Background and Aims Lymphocytes populate the livers of infants with biliary atresia, but it is unknown whether neonatal lymphocytes regulate pathogenesis of disease. Here, we investigate this question by examining the role of T lymphocytes in the destruction of extrahepatic bile ducts of neonatal mice using an experimental model of biliary atresia. Methods Inoculation of neonatal mice with rhesus rotavirus followed by multi-staining flow cytometry to quantify expression of Ifng by hepatic lymphocytes, and real-time PCR for mRNA expression of pro-inflammatory cytokines. This was followed by determining the consequences of antibody-mediated depletion of lymphocyte subtypes on the development of biliary obstruction, and co-culture and cell transfer experiments to investigate the effector role of lymphocyte subtypes on neonatal biliary disease. Results Rotavirus infection results in overexpression of Ifng by neonatal hepatic T cells. Among these cells, depletion of CD4+ cells did not change the course of inflammatory injury and obstruction of neonatal bile ducts. In contrast, loss of CD8+ cells remarkably suppressed duct injury, prevented luminal obstruction, and restored bile flow. Co-culture experiments showed that rotavirus-primed, but not naïve, CD8+ cells were cytotoxic to cholangiocytes. In adoptive transfer experiments, we found that primed CD8+ cells preferentially homed to extrahepatic bile ducts of neonatal mice and invaded their epithelial lining. Conclusion Primed neonatal CD8+ cells can activate a proinflammatory program, target diseased and healthy duct epithelium, and drive the phenotypic expression of biliary atresia, thus constituting a potential therapeutic target to halt disease progression.

Shivakumar, Pranavkumar; Sabla, Gregg; Mohanty, Sujit; McNeal, Monica; Ward, Richard; Stringer, Keith; Caldwell, Charles; Chougnet, Claire; Bezerra, Jorge A.

2007-01-01

359

Type III effectors orchestrate a complex interplay between transcriptional networks to modify basal defence responses during pathogenesis and resistance.  

PubMed

To successfully infect a plant, bacterial pathogens inject a collection of Type III effector proteins (TTEs) directly into the plant cell that function to overcome basal defences and redirect host metabolism for nutrition and growth. We examined (i) the transcriptional dynamics of basal defence responses between Arabidopsis thaliana and Pseudomonas syringae and (ii) how basal defence is subsequently modulated by virulence factors during compatible interactions. A set of 96 genes displaying an early, sustained induction during basal defence was identified. These were also universally co-regulated following other bacterial basal resistance and non-host responses or following elicitor challenges. Eight hundred and eighty genes were conservatively identified as being modulated by TTEs within 12 h post-inoculation (hpi), 20% of which represented transcripts previously induced by the bacteria at 2 hpi. Significant over-representation of co-regulated transcripts encoding leucine rich repeat receptor proteins and protein phosphatases were, respectively, suppressed and induced 12 hpi. These data support a model in which the pathogen avoids detection through diminution of extracellular receptors and attenuation of kinase signalling pathways. Transcripts associated with several metabolic pathways, particularly plastid based primary carbon metabolism, pigment biosynthesis and aromatic amino acid metabolism, were significantly modified by the bacterial challenge at 12 hpi. Superimposed upon this basal response, virulence factors (most likely TTEs) targeted genes involved in phenylpropanoid biosynthesis, consistent with the abrogation of lignin deposition and other wall modifications likely to restrict the passage of nutrients and water to the invading bacteria. In contrast, some pathways associated with stress tolerance are transcriptionally induced at 12 hpi by TTEs. PMID:16553893

Truman, William; de Zabala, Marta Torres; Grant, Murray

2006-04-01

360

Intravenous gammaglobulin suppresses inflammation through a novel TH2 pathway  

PubMed Central

High-dose intravenous immunoglobulin is a widely used therapeutic preparation of highly purified immunoglobulin G (IgG) antibodies. It is administered at high doses (1–2 grams per kilogram) for the suppression of autoantibody-triggered inflammation in a variety of clinical settings1. This anti-inflammatory activity of intravenous immunoglobulin is triggered by a minor population of IgG crystallizable fragments (Fcs), with glycans terminating in ?2,6 sialic acids (sFc) that target myeloid regulatory cells expressing the lectin dendritic-cell-specific ICAM-3 grabbing non-integrin (DC-SIGN; also known as CD209)2–4. Here, to characterize this response in detail, we generated humanized DC-SIGN mice (hDC-SIGN), and demonstrate that the anti-inflammatory activity of intravenous immunoglobulin can be recapitulated by the transfer of bone-marrow-derived sFc-treated hDC-SIGN+ macrophages or dendritic cells into naive recipients. Furthermore, sFc administration results in the production of IL-33, which, in turn, induces expansion of IL-4-producing basophils that promote increased expression of the inhibitory Fc receptor Fc?RIIB on effector macrophages. Systemic administration of the TH2 cytokines IL-33 or IL-4 upregulates Fc?RIIB on macrophages, and suppresses serum-induced arthritis. Consistent with these results, transfer of IL-33-treated basophils suppressed induced arthritic inflammation. This novel DC-SIGN–TH2 pathway initiated by an endogenous ligand, sFc, pro-vides an intrinsic mechanism for maintaining immune homeostasis that could be manipulated to provide therapeutic benefit in auto-immune diseases.

Anthony, Robert M.; Kobayashi, Toshihiko; Wermeling, Fredrik; Ravetch, Jeffrey V.

2012-01-01

361

Saccade suppression exerts global effects on the motor system.  

PubMed

Stopping inappropriate eye movements is a cognitive control function that allows humans to perform well in situations that demand attentional focus. The stop-signal task is an experimental model for this behavior. Participants initiate a saccade toward a target and occasionally have to try to stop the impending saccade if a stop signal occurs. Prior research using a version of this paradigm for limb movements (hand, leg) as well as for speech has shown that rapidly stopping action leads to apparently global suppression of the motor system, as indexed by the corticospinal excitability (CSE) of task-unrelated effectors in studies with transcranial magnetic stimulation (TMS) of M1. Here we measured CSE from the hand with high temporal precision while participants made saccades and while they successfully and unsuccessfully stopped these saccades in response to a stop signal. We showed that 50 ms before the estimated time at which a saccade is successfully stopped there was reduced CSE for the hand, which was task irrelevant. This shows that rapidly stopping eye movements also has global motor effects. We speculate that this arises because rapidly stopping eye movements, like skeleto-motor movements, is possibly achieved via input to the subthalamic nucleus of the basal ganglia, with a putatively broad suppressive effect on thalamocortical drive. Since recent studies suggest that this suppressive effect could also impact nonmotor representations, the present finding points to a possible mechanistic basis for some kinds of distractibility: abrupt-onset stimuli will interrupt ongoing processing by generating global motor and nonmotor effects. PMID:23699058

Wessel, Jan R; Reynoso, H Sequoyah; Aron, Adam R

2013-05-22

362

Do Postures of Distal Effectors Affect the Control of Actions of Other Distal Effectors? Evidence for a System of Interactions between Hand and Mouth  

PubMed Central

The present study aimed at determining whether, in healthy humans, postures assumed by distal effectors affect the control of the successive grasp executed with other distal effectors. In experiments 1 and 2, participants reached different objects with their head and grasped them with their mouth, after assuming different hand postures. The postures could be implicitly associated with interactions with large or small objects. The kinematics of lip shaping during grasp varied congruently with the hand posture, i.e. it was larger or smaller when it could be associated with the grasping of large or small objects, respectively. In experiments 3 and 4, participants reached and grasped different objects with their hand, after assuming the postures of mouth aperture or closure (experiment 3) and the postures of toe extension or flexion (experiment 4). The mouth postures affected the kinematics of finger shaping during grasp, that is larger finger shaping corresponded with opened mouth and smaller finger shaping with closed mouth. In contrast, the foot postures did not influence the hand grasp kinematics. Finally, in experiment 5 participants reached-grasped different objects with their hand while pronouncing opened and closed vowels, as verified by the analysis of their vocal spectra. Open and closed vowels induced larger and smaller finger shaping, respectively. In all experiments postures of the distal effectors induced no effect, or only unspecific effects on the kinematics of the reach proximal/axial component. The data from the present study support the hypothesis that there exists a system involved in establishing interactions between movements and postures of hand and mouth. This system might have been used to transfer a repertoire of hand gestures to mouth articulation postures during language evolution and, in modern humans, it may have evolved a system controlling the interactions existing between speech and gestures.

Gentilucci, Maurizio; Campione, Giovanna Cristina

2011-01-01

363

Isoflavones, genistein and daidzein, regulate mucosal immune response by suppressing dendritic cell function.  

PubMed

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

2012-10-22

364

HPGE Compton-Suppression and Pair Spectrometer.  

National Technical Information Service (NTIS)

A HPGe detector incorporated into a Compton suppression and pair spectrometer yields a continuum suppression factor of over 30. Cryostat housing requirements to obtain such suppression are discussed, sample spectra are presented, and several experiments m...

D. C. Camp

1976-01-01

365

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.

2011-01-01

366

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.

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

367

PLA2R1 Mediates Tumor Suppression by Activating JAK2.  

PubMed

Little is known about the physiological role of the phospholipase A2 receptor (PLA2R1). PLA2R1 has been described as regulating the replicative senescence, a telomerase-dependent proliferation arrest. The downstream PLA2R1 signaling and its role in cancer are currently unknown. Senescence induction in response to activated oncogenes is a failsafe program of tumor suppression that must be bypassed for tumorigenesis. We now present evidence that PLA2R1 functions in vitro as a tumor suppressor, the depletion of which is sufficient to escape oncogene-induced senescence (OIS), thereby facilitating oncogenic cell transformation. Furthermore, mice that are genetically deficient in PLA2R1 display increased sensitivity to RAS-induced tumorigenesis by facilitating OIS escape, highlighting its physiological role as a tumor suppressor. Unexpectedly, PLA2R1 activated JAK2 and its effector signaling, with PLA2R1-mediated inhibition of cell transformation largely reverted in JAK2-depleted cells. This finding was unexpected as the JAK2 pathway has been associated mainly with protumoral functions and several inhibitors are currently in clinical trials. Taken together, our findings uncover an unanticipated tumor suppressive role for PLA2R1 that is mediated by targeting downstream JAK2 effector signaling. Cancer Res; 73(20); 6334-45. ©2013 AACR. PMID:24008317

Vindrieux, David; Augert, Arnaud; Girard, Christophe A; Gitenay, Delphine; Lallet-Daher, Helene; Wiel, Clotilde; Le Calvé, Benjamin; Gras, Baptiste; Ferrand, Mylène; Verbeke, Stéphanie; de Launoit, Yvan; Leroy, Xavier; Puisieux, Alain; Aubert, Sébastien; Perrais, Michael; Gelb, Michael; Simonnet, Hélène; Lambeau, Gérard; Bernard, David

2013-09-05

368

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

2011-12-24

369

Cannabinoid Mechanisms of Pain Suppression  

Microsoft Academic Search

A large body of literature indicates that cannabinoids suppress behavioral responses to acute and persistent noxious stimulation\\u000a in animals. This review exax mines neuroanatomical, behavioral, and neurophysiological evidence supporting a role for cannabinoids\\u000a in suppressing pain at spinal, supraspinal, and peripheral levels. Localization studies employing receptor binding and quantitative\\u000a autoradiography, immunocytochemistry, and in situ hybridization are reviewed to examine the

J. M. Walker; A. G. Hohmann

370

In Vivo Treg Suppression Assays  

PubMed Central

To fully examine the functionality of a regulatory T cell (Treg) population, one needs to assess their ability to suppress in a variety of in vivo models. We describe five in vivo models that examine the suppressive capacity of Tregs upon different target cell types. The advantages and disadvantages of each model includ ing resources, time, and technical expertise required to execute each model are also described.

Workman, Creg J.; Collison, Lauren W.; Bettini, Maria; Pillai, Meenu R.; Rehg, Jerold E.; Vignali, Dario A.A.

2011-01-01

371

A formula for charmonium suppression  

SciTech Connect

In this work a formula for charmonium suppression obtained by Matsui in 1989 is analytically generalized for the case of complex cc-barpotential described by a 3-dimensional and isotropic time-dependent harmonic oscillator (THO). It is suggested that under certain scheme the formula can be applied to describe J/{psi} suppression in heavy-ion collisions at CERN-SPS, RHIC, and LHC with the advantage of analytical tractability.

Pena, C., E-mail: pena@ift.uni.wroc.pl; Blaschke, D., E-mail: blaschke@ift.uni.wroc.pl [University of Wroclaw, Institute for Theoretical Physics (Poland)

2012-07-15

372

A novel effector secretion mechanism based on proton-motive force-dependent type III secretion apparatus rotation.  

PubMed

The type III secretion apparatus (T3SA) participates in the secretion of bacterial proteins called effectors, although the detailed mechanism of effector secretion remains unclear. T3SA and flagellum were shown to branch from a common ancestor and also show structural similarity. In addition, both T3SA-dependent effector secretion and flagellar rotation were reported to require proton-motive force (PMF) for activity. From these reports, we hypothesized that T3SA, like the flagellum, would rotate via PMF and that this rotation is responsible for effector secretion. To observe T3SA rotation, we constructed a novel observation system by modifying the tip of T3SA on bacterial cell membranes with an observation probe, which allowed documentation of T3SA rotation for the first time. T3SA rotation was stopped by the addition of a protonophore that decreases PMF. Moreover, increased viscosity of the observation medium inhibited both rotation of T3SA associated with beads and effector secretion. These results suggested that effector secretion would follow the PMF-dependent rotation of T3SA and could be inhibited by preventing T3SA rotation. Moreover, the motion-track analysis of bead rotation suggested that the T3SA needle might be flexible. Consequently, we propose a "rotational secretion model" as a novel effector secretion mechanism of T3SA. PMID:23515444

Ohgita, Takashi; Hayashi, Naoki; Hama, Susumu; Tsuchiya, Hiroyuki; Gotoh, Naomasa; Kogure, Kentaro

2013-03-20

373

A ligation-independent cloning technique for high-throughput assembly of transcription activator–like effector genes.  

PubMed

Transcription activator–like (TAL) effector proteins derived from Xanthomonas species have emerged as versatile scaffolds for engineering DNA-binding proteins of user-defined specificity and functionality. Here we describe a rapid, simple, ligation-independent cloning (LIC) technique for synthesis of TAL effector genes. Our approach is based on a library of DNA constructs encoding individual TAL effector repeat unit combinations that can be processed to contain long, unique single-stranded DNA overhangs suitable for LIC. Assembly of TAL effector arrays requires only the combinatorial mixing of fluids and has exceptional fidelity. TAL effector nucleases (TALENs) produced by this method had high genome-editing activity at endogenous loci in HEK 293T cells (64% were active). To maximize throughput, we generated a comprehensive 5-mer TAL effector repeat unit fragment library that allows automated assembly of >600 TALEN genes in a single day. Given its simplicity, throughput and fidelity, LIC assembly will permit the generation of TAL effector gene libraries for large-scale functional genomics studies. PMID:23242165

Schmid-Burgk, Jonathan L; Schmidt, Tobias; Kaiser, Vera; Höning, Klara; Hornung, Veit

2013-01-01

374

Chronic transplantation immunity in newts: temperature susceptibility of an effector phase in allo-skin graft rejection.  

PubMed

Urodele amphibians are unique due to their greatly reduced immune responsiveness compared to bony fishes, which show acute immune responsiveness. In newts, the mean survival time of allogenic skin grafts in the transplantation immunity was 48.8 ± 8.3 days at 25°C, suggesting that it occurs in a chronic manner. The graft rejection process was categorized into three stages: a latent stage with frequent blood circulation, or the immune induction phase; a vascular stoppage stage with dominant infiltrating cells of T cells; and a rejection stage showing the change of the dominant cells to monocytes/macrophages, probably as effector cells, tetntatively referred to as the immune effector phase. The immune induction phase is susceptible to the cyclophosphamide (CY) mitosis inhibitor, but not to a temperature shift from 18 to 27°C, while the immune effector phase is susceptible to temperature shifts, but not CY-treatment, although the temperature shift failed to shorten the graft survival time to less than 25 days, which nearly equals that of the secondary set of grafts where the lack of complete blood circulation is remarkable and graft rejection is resistant to CY-treatment. In contrast, a very low temperature (5-10°C) completely prevented effector generation in newts; in frogs, however, it is reported that such low temperatures did not prevent the generation of effectors. Taken together, these data suggest that chronic responses in newts are due to effector cells other than cytotoxic T cells; possible effector cells are discussed. PMID:21728799

Kinefuchi, Kenjiroh; Kushida, Yoshihiro; Johnouchi, Masato; Shimizu, Yuiko; Ohneda, Hikaru; Fujii, Masato; Hosono, Masamichi

2011-07-01

375

The target cell plasma membrane is a critical interface for Salmonella cell entry effector-host interplay.  

PubMed

Salmonella species trigger host membrane ruffling to force their internalization into non-phagocytic intestinal epithelial cells. This requires bacterial effector protein delivery into the target cell via a type III secretion system. Six translocated effectors manipulate cellular actin dynamics, but how their direct and indirect activities are spatially and temporally co-ordinated to promote productive cytoskeletal rearrangements remains essentially unexplored. To gain further insight into this process, we applied mechanical cell fractionation and immunofluorescence microscopy to systematically investigate the subcellular localization of epitope-tagged effectors in transiently transfected and Salmonella-infected cultured cells. Although five effectors contain no apparent membrane-targeting domains, all six localized exclusively in the target cell plasma membrane fraction and correspondingly were visualized at the cell periphery, from where they induced distinct effects on the actin cytoskeleton. Unexpectedly, no translocated effector pool was detectable in the cell cytosol. Using parallel in vitro assays, we demonstrate that the prenylated cellular GTPase Cdc42 is necessary and sufficient for membrane association of the Salmonella GTP exchange factor and GTPase-activating protein mimics SopE and SptP, which have no intrinsic lipid affinity. The data show that the host plasma membrane is a critical interface for effector-target interaction, and establish versatile systems to further dissect effector interplay. PMID:15522075

Cain, Robert J; Hayward, Richard D; Koronakis, Vassilis

2004-11-01

376

HIV Controllers Maintain a Population of Highly Efficient Th1 Effector Cells in Contrast to Patients Treated in the Long Term  

PubMed Central

HIV controllers are rare individuals who spontaneously control HIV replication in the absence of antiretroviral therapy. To identify parameters of the CD4 response that may contribute to viral control rather than merely reflect a persistently low viremia, we compared the T helper profiles in two groups of patients with more than 10 years of viral suppression: HIV controllers from the Agence Nationale de Recherche sur le SIDA et les Hépatites Virales (ANRS) CO18 cohort (n = 26) and efficiently treated patients (n = 16). Cells specific for immunodominant Gag and cytomegalovirus (CMV) peptides were evaluated for the production of 10 cytokines and cytotoxicity markers and were also directly quantified ex vivo by major histocompatibility complex (MHC) class II tetramer staining. HIV controller CD4+ T cells were characterized by a higher frequency of gamma interferon (IFN-?) production, perforin+/CD107a+ expression, and polyfunctionality in response to Gag peptides. While interleukin 4 (IL-4), IL-17, and IL-21 production did not differ between groups, the cells of treated patients produced more IL-10 in response to Gag and CMV peptides, pointing to persistent negative immunoregulation after long-term antiretroviral therapy. Gag293 tetramer-positive cells were detected at a high frequency (0.12%) and correlated positively with IFN-?-producing CD4+ T cells in the controller group (R = 0.73; P = 0.003). Tetramer-positive cells were fewer in the highly active antiretroviral therapy (HAART) group (0.04%) and did not correlate with IFN-? production, supporting the notion of a persistent immune dysfunction in HIV-specific CD4+ T cells of treated patients. In conclusion, HIV controllers maintained a population of highly efficient Th1 effectors directed against Gag in spite of a persistently low antigenemia, while patients treated in the long term showed a loss of CD4 effector functions.

Vingert, Benoit; Benati, Daniela; Lambotte, Olivier; de Truchis, Pierre; Slama, Laurence; Jeannin, Patricia; Galperin, Moran; Perez-Patrigeon, Santiago; Boufassa, Faroudy; Kwok, William W.; Lemaitre, Fabrice; Delfraissy, Jean-Francois; Theze, Jacques

2012-01-01

377

FoxO1 controls effector-to-memory transition and maintenance of functional CD8 T cell memory.  

PubMed

During a T cell response, naive CD8 T cells differentiate into effector cells. Subsequently, a subset of effector cells termed memory precursor effector cells further differentiates into functionally mature memory CD8 T cells. The transcriptional network underlying this carefully scripted process is not well understood. In this study, we report that the transcription factor FoxO1 plays an integral role in facilitating effector-to-memory transition and functional maturation of memory CD4 and CD8 T cells. We find that FoxO1 is not required for differentiation of effector cells, but in the absence of FoxO1, memory CD8 T cells displayed features of senescence and progressive attrition in polyfunctionality, which in turn led to impaired recall responses and poor protective immunity. These data suggest that FoxO1 is essential for maintenance of functional CD8 T cell memory and protective immunity. Under competing conditions in bone marrow chimeric mice, FoxO1 deficiency did not perturb clonal expansion or effector differentiation. Instead, FoxO1-deficient memory precursor effector cells failed to survive and form memory CD8 T cells. Mechanistically, FoxO1 deficiency perturbed the memory CD8 T cell transcriptome, characterized by pronounced alterations in the expression of genes that encode transcription factors (including Tcf7), effector molecules, cell cycle regulators, and proteins that regulate fatty acid, purine, and pyramidine metabolism and mitochondrial functions. We propose that FoxO1 is a key regulator that reprograms and steers the differentiation of effector cells to functionally competent memory cells. These findings have provided fundamental insights into the mechanisms that regulate the quality of CD8 T cell memory to intracellular pathogens. PMID:23733882

Tejera, Melba Marie; Kim, Eui Ho; Sullivan, Jeremy A; Plisch, Erin H; Suresh, M

2013-06-03

378

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.

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

379

Mechanisms of cross-suppression of TNP-specific plaque forming cell responses by TMA-specific first-order T suppressor factor  

SciTech Connect

The addition of hybridoma-derived phenyltrimethylammonium (TMA)-specific first-order T suppressor factor (TsF/sub 1/) into cultures containing Brucella abortus coupled with the TMA and trinitrophenol haptens (TMA-BA-TNP) results in the cross-suppression of TNP-specific plaque forming cell (PFC) responses. The suppression mediated by TMA-TsF/sub 1/ is dependent on the presence of T cells and specific antigen (TMA). Subculturing of whole spleen cells with TMA-TsF/sub 1/ and specific soluble antigen (TMA-BSA) is able to induce suppressor T cells which cross-suppress the TNP-specific PFC of spleen cell cultures stimulated with TMA-BA-TNP in an antigen (TMA)-dependent manner at the effector phase of the response. The effector acting T suppressor cells (Tse) are nylon wool nonadherent and appears to require whole spleen cells in responding cultures for suppression, suggesting that the target of the Tse is not the TNP-specific B cell. The authors are presently characterizing the mechanisms of cross-suppression by TMA-TsF/sub 1/ and Tse utilizing the described primary in vitro antibody assay.

Jendrisak, G.S.; Bellone, C.J.

1986-03-05

380

Suppressed Charmed B Decay  

SciTech Connect

This thesis describes the measurement of the branching fractions of the suppressed charmed B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decays and the non-resonant B{sup 0} {yields} D{sup (*)-} {eta}{pi}{sup +} decays in approximately 230 million {Upsilon}(4S) {yields} B{bar B} events. The data have been collected with the BABAR detector at the PEP-II B factory at the Stanford Linear Accelerator Center in California. Theoretical predictions of the branching fraction of the B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decays show large QCD model dependent uncertainties. Non-factorizing terms, in the naive factorization model, that can be calculated by QCD factorizing models have a large impact on the branching fraction of these decay modes. The predictions of the branching fractions are of the order of 10{sup -6}. The measurement of the branching fraction gives more insight into the theoretical models. In general a better understanding of QCD models will be necessary to conduct weak interaction physics at the next level. The presence of CP violation in electroweak interactions allows the differentiation between matter and antimatter in the laws of physics. In the Standard Model, CP violation is incorporated in the CKM matrix that describes the weak interaction between quarks. Relations amongst the CKM matrix elements are used to present the two relevant parameters as the apex of a triangle (Unitarity Triangle) in a complex plane. The over-constraining of the CKM triangle by experimental measurements is an important test of the Standard Model. At this moment no stringent direct measurements of the CKM angle {gamma}, one of the interior angles of the Unitarity Triangle, are available. The measurement of the angle {gamma} can be performed using the decays of neutral B mesons. The B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decay is sensitive to the angle {gamma} and, in comparison to the current decays that are being employed, could significantly enhance the measurement of this angle. However, the low expected branching fraction for the B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decay channels could severely impact the measurement. A prerequisite of the measurement of the CKM angle is the observation of the B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decay on which this thesis reports. The BABAR experiment consists of the BABAR detector and the PEP-II e{sup +}e{sup -} collider. The design of the experiment has been optimized for the study of CP violation in the decays of neutral B mesons but is also highly suitable for the search for rare B decays such as the B{sup 0} {yields} D{sup (*)-} a{sub 0}{sup +} decay. The PEP-II collider operates at the {Upsilon}(4S) resonance and is a clean source of B{bar B} meson pairs.

Snoek, Hella Leonie; /Vrije U., Amsterdam

2011-11-28

381

Effector and regulatory T cell subsets in autoimmunity and tissue inflammation  

PubMed Central

Many autoimmune diseases are driven by self-reactive T helper cells. Until recently, organ-specific autoimmune diseases were primarily associated with Th1 cells but not Th2 cells. However, the discovery of a number of new effector T cell subsets, like Th17 and Th9 cells, and regulatory T cells, like Tregs and Tr1 cells, has changed the way we view and understand autoimmunity at cellular and molecular levels. In recent years, IL-17 producing Th17 cells have emerged as major players in autoimmunity. The complicated relationship between Th1 and Th17 cells, as well as the intricate balance between Tregs and Th17 cells, provide a basis for understanding the immunological mechanisms that induce and regulate autoimmunity. Here, we give an overview of the interplay between different effector T cell subsets and regulatory T cell subsets, and how they contribute to the development of autoimmunity and tissue inflammation.

Jager, Anneli; Kuchroo, Vijay K.

2011-01-01

382

Aging effects on sensorimotor integration: a comparison of effector systems and feedback modalities.  

PubMed

Research on motor aging has focused on visuomotor effects in limb musculature, with few comparisons across effectors or feedback modalities. The authors examined steady fine force control in oral and manual effectors under visual and auditory feedback in 13 young (19-23 years old) and 13 older (60-77 years old) participants, hypothesizing that force variability would increase with aging (a) more in the finger than the lip and (b) for both feedback modalities. The magnitude of variability increased with age for both visuomotor and audiomotor tasks but age-related differences were greater in the lip than the finger. These results point to increased variability as a potential early marker of changing motor function (prior to loss of strength) that extends beyond the visuomotor system. PMID:23611289

Bronson-Lowe, Christina R; Loucks, Torrey M; Ofori, Edward; Sosnoff, Jacob J

2013-04-23

383

Bacterial Effector-Involved Temporal and Spatial Regulation by Hijack of the Host Ubiquitin Pathway  

PubMed Central

Ubiquitination is one of the most conserved post-translational modifications of proteins, and is involved in essential eukaryotic cellular processes. These include protein degradation, transcriptional regulation, cell-cycle progression, and signaling. Microbial pathogens have evolved sophisticated systems to hijack host cellular functions for their own benefit. Central to these systems are protein transport machineries; many pathogenic bacteria inject “effector proteins” to modulate host cellular processes including the ubiquitin pathway. Numerous bacterial pathogens have been found to modulate the host ubiquitin system in various ways. In this review, we focus on three examples of temporal and spatial regulation of bacterial effectors, which are mediated by the host ubiquitin system. Subversion of the host ubiquitin system must be a widespread strategy among pathogenic bacteria to accomplish successful infection.

Kubori, Tomoko; Nagai, Hiroki

2011-01-01

384

Vaccine-induced effector-memory CD8+ T cell responses predict therapeutic efficacy against tumors.  

PubMed

CD8(+) T cells have the potential to attack and eradicate cancer cells. The efficacy of therapeutic vaccines against cancer, however, lacks defined immune correlates of tumor eradication after (therapeutic) vaccination based on features of Ag-specific T cell responses. In this study, we examined CD8(+) T cell responses elicited by various peptide and TLR agonist-based vaccine formulations in nontumor settings and show that the formation of CD62L(-)KLRG1(+) effector-memory CD8(+) T cells producing the effector cytokines IFN-? and TNF predicts the degree of therapeutic efficacy of these vaccines against established s.c. tumors. Thus, characteristics of vaccine-induced CD8(+) T cell responses instill a predictive determinant for the efficacy of vaccines during tumor therapy. PMID:22914049

van Duikeren, Suzanne; Fransen, Marieke F; Redeker, Anke; Wieles, Brigitte; Platenburg, Gerard; Krebber, Willem-Jan; Ossendorp, Ferry; Melief, Cornelis J M; Arens, Ramon

2012-08-22

385

Coupling of agonist binding to effector domain activation in metabotropic glutamate-like receptors.  

PubMed

Many membrane receptors are made of a ligand binding domain and an effector domain mediating intracellular signaling. This is the case for the metabotropic glutamate-like G-protein-coupled receptors. How ligand binding leads to the active conformation of the effector domain in such receptors is largely unknown. Here, we used an evolutionary trace analysis and mutagenesis to identify critical residues involved in the allosteric coupling between the Venus flytrap ligand binding domain (VFT) and the heptahelical G-protein activating domain of the metabotropic glutamate-like receptors. We have shown that a conserved interdomain disulfide bridge is required for this allosteric interaction. Taking into account that these receptors are homodimers, this finding provides important new information explaining how the different conformations of the dimer of VFT lead to different signaling of such dimeric receptors. PMID:16787923

Rondard, Philippe; Liu, Jianfeng; Huang, Siluo; Malhaire, Fanny; Vol, Claire; Pinault, Alexia; Labesse, Gilles; Pin, Jean-Philippe

2006-06-20

386

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

387

The crystal structure of TAL effector PthXo1 bound to its DNA target.  

PubMed

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. PMID:22223736

Mak, Amanda Nga-Sze; Bradley, Philip; Cernadas, Raul A; Bogdanove, Adam J; Stoddard, Barry L

2012-01-05

388

Effector CD4+ T cells, the cytokines they generate, and GVHD: something old and something new  

PubMed Central

GVHD is a syndrome that results from minor and major histocompatibility complex incompatibilities between the donor and recipient. More than 50 years after its initial description, the pathophysiology of GVHD remains poorly understood. Nonetheless, donor T cells have been shown to be critical to the pathophysiology of acute and chronic GVHD, yet precisely how they function remains unclear. The effector mechanisms by which donor T cells mediate tissue inflammation is even less well understood. Identification of several new lineages of CD4+ T cells made in the past decade and their roles in the pathophysiology of T cell–mediated diseases has shed new light on these effector mechanisms. In this review, we summarize the recent descriptions of these T-cell lineages and the current data supporting their role in acute and to a lesser extent chronic GVHD. Investigations into the activity of these new T-cell lineages may provide more rationale approaches to the treatment or prevention of GVHD.

Coghill, James M.; Sarantopoulos, Stefanie; Moran, Timothy P.; Murphy, William J.; Blazar, Bruce R.

2011-01-01

389

The Yersinia virulence effector YopM binds caspase-1 to arrest inflammasome assembly and processing.  

PubMed

Inflammasome assembly activates caspase-1 and initiates the inflammatory cell death program pyroptosis, which is protective against numerous pathogens. Consequently, several pathogens, including the plague causing bacterium Yersinia pestis, avoid activating this pathway to enhance their virulence. However, bacterial molecules that directly modulate the inflammasome have yet to be identified. Examining the contribution of Yersinia type III secretion effectors to caspase-1 activation, we identified the leucine-rich repeat effector YopM as a potent antagonist of both caspase-1 activity and activation. YopM directly binds caspase-1, which both inhibits caspase-1 activity and sequesters it to block formation of the mature inflammasome. Caspase-1 activation antagonizes Yersinia survival in vivo, and consequently YopM inhibition of caspase-1 is required for Yersinia pathogenesis. Thus, a bacterium obstructs pyroptosis utilizing a direct mechanism of caspase-1 inhibition that is distinct from known viral or host inhibitors. PMID:23245324

LaRock, Christopher N; Cookson, Brad T

2012-12-13

390

Late-onset rubella syndrome: coexistence of immune complex disease and defective cytotoxic effector cell function.  

PubMed

We studied a classical case of late-onset rubella syndrome characterized by multi-organ disease and persistence of live rubella virus in spite of high titres of specific antirubella antibodies and presence of large amounts of circulating immune complexes. When first studied at the age of 5 months there was a low proportion of T8+ lymphocytes. Functional studies revealed decreased activity of K and NK cells as well as alloreactive direct cytotoxic cells (CTL). Removal of cell-bound immunoglobulin and immune complexes tended to improve K and NK cell function in vitro. Plasma exchange transfusions carried out at 9 months of age resulted in clinical improvement. Normalization of cytotoxic effector cell functions and cessation of viremia accompanied recovery from active disease. The results indicate that defective cytotoxic effector cell function is the primary cause for the defective virus elimination in this syndrome. PMID:2938855

Verder, H; Dickmeiss, E; Haahr, S; Kappelgaard, E; Leerbøy, J; Møller-Larsen, A; Nielsen, H; Platz, P; Koch, C

1986-02-01

391

Late-onset rubella syndrome: coexistence of immune complex disease and defective cytotoxic effector cell function.  

PubMed Central

We studied a classical case of late-onset rubella syndrome characterized by multi-organ disease and persistence of live rubella virus in spite of high titres of specific antirubella antibodies and presence of large amounts of circulating immune complexes. When first studied at the age of 5 months there was a low proportion of T8+ lymphocytes. Functional studies revealed decreased activity of K and NK cells as well as alloreactive direct cytotoxic cells (CTL). Removal of cell-bound immunoglobulin and immune complexes tended to improve K and NK cell function in vitro. Plasma exchange transfusions carried out at 9 months of age resulted in clinical improvement. Normalization of cytotoxic effector cell functions and cessation of viremia accompanied recovery from active disease. The results indicate that defective cytotoxic effector cell function is the primary cause for the defective virus elimination in this syndrome.

Verder, H; Dickmeiss, E; Haahr, S; Kappelgaard, E; Leerb?y, J; M?ller-Larsen, A; Nielsen, H; Platz, P; Koch, C

1986-01-01

392

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.

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

393

Terminal sugars of Fc glycans influence antibody effector functions of IgGs.  

PubMed

IgG molecules contain glycans in the CH2 domain of the Fc fragment (N-glycosylation) which are highly heterogeneous, because of the presence of different terminal sugars. The heterogeneity of Fc glycans varies with species and expression system. Fc glycans influence the binding of IgG to Fc receptors and C1q, and are therefore important for IgG effector functions. Specifically, terminal sugars such as sialic acids, core fucose, bisecting N-acetylglucosamine, and mannose residues affect the binding of IgG to the FcgammaRIIIa receptor and thereby influence ADCC activity. By contrast, terminal galactose residues affect antibody binding to C1q and thereby modulate CDC activity. Structural studies indicate that the presence or absence of specific terminal sugars may affect hydrophilic and hydrophobic interactions between sugar residues and amino acid residues in the Fc fragment, which in turn may impact antibody effector functions. PMID:18606225

Raju, T Shantha

2008-07-17

394

The crystal structure of TAL effector PthXo1 bound to its DNA target  

PubMed Central

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 using 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 N-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.

2012-01-01

395

Neuron specific Rab4 effector GRASP1 coordinates membrane specialization and maturation of recycling endosomes  

Microsoft Academic Search

The endosomal pathway in neuronal dendrites is essential for membrane receptor trafficking and proper synaptic function and plasticity. However, the molecular mechanisms that organize specific endocytic trafficking routes are poorly understood. Here, we identify GRIP-associated protein-1 (GRASP-1) as a neuron-specific effector of Rab4 and key component of the molecular machinery that coordinates recycling endosome maturation in dendrites. We show that

Casper C. Hoogenraad; Ioana Popa; Kensuke Futai; Emma Sanchez-Martinez; Phebe S. Wulf; Thijs van Vlijmen; Bjorn R. Dortland; Viola Oorschot; Roland Govers; Maria Monti; Albert J. R. Heck; Morgan Sheng; Judith Klumperman; Holger Rehmann; Dick Jaarsma; Lukas C. Kapitein; Peter van der Sluijs

2010-01-01

396

Precursor and Effector Dependency of Lipid Synthesis in Amyloplasts Isolated from Developing Maize and Wheat Endosperm  

Microsoft Academic Search

Recently, we developed a method for the isolation of amyloplasts from maize endosperm. Here we describe a new protocol for the isolation of intact and pure amyloplasts from developing wheat endosperm. The precursor and effector dependencies of fatty-acid synthesis were analysed for both types of cereal amyloplasts. Both wheat and maize-endosperm amyloplasts used [214C]pyruvate with the greatest efficiency for the

T. Möhlmann; H. E. Neuhaus

1997-01-01

397

MiR221 Influences Effector Functions and Actin Cytoskeleton in Mast Cells  

Microsoft Academic Search

Mast cells have essential effector and immunoregulatory functions in IgE-associated allergic disorders and certain innate and adaptive immune responses, but the role of miRNAs in regulating mast cell functions is almost completely unexplored. To examine the role of the activation-induced miRNA miR-221 in mouse mast cells, we developed robust lentiviral systems for miRNA overexpression and depletion. While miR-221 favored mast

Ramon J. Mayoral; Lorenzo Deho; Nicole Rusca; Nenad Bartonicek; Harpreet Kaur Saini; Anton J. Enright; Silvia Monticelli

2011-01-01

398

Structural Basis for Type VI Secretion Effector Recognition by a Cognate Immunity Protein  

PubMed Central

The type VI secretion system (T6SS) has emerged as an important mediator of interbacterial interactions. A T6SS from Pseudomonas aeruginosa targets at least three effector proteins, type VI secretion exported 1–3 (Tse1–3), to recipient Gram-negative cells. The Tse2 protein is a cytoplasmic effector that acts as a potent inhibitor of target cell proliferation, thus providing a pronounced fitness advantage for P. aeruginosa donor cells. P. aeruginosa utilizes a dedicated immunity protein, type VI secretion immunity 2 (Tsi2), to protect against endogenous and intercellularly-transferred Tse2. Here we show that Tse2 delivered by the T6SS efficiently induces quiescence, not death, within recipient cells. We demonstrate that despite direct interaction of Tsi2 and Tse2 in the cytoplasm, Tsi2 is dispensable for targeting the toxin to the secretory apparatus. To gain insights into the molecular basis of Tse2 immunity, we solved the 1.00 Å X-ray crystal structure of Tsi2. The structure shows that Tsi2 assembles as a dimer that does not resemble previously characterized immunity or antitoxin proteins. A genetic screen for Tsi2 mutants deficient in Tse2 interaction revealed an acidic patch distal to the Tsi2 homodimer interface that mediates toxin interaction and immunity. Consistent with this finding, we observed that destabilization of the Tsi2 dimer does not impact Tse2 interaction. The molecular insights into Tsi2 structure and function garnered from this study shed light on the mechanisms of T6 effector secretion, and indicate that the Tse2–Tsi2 effector–immunity pair has features distinguishing it from previously characterized toxin–immunity and toxin–antitoxin systems.

Li, Mo; Le Trong, Isolde; Carl, Mike A.; Larson, Eric T.; Chou, Seemay; De Leon, Justin A.; Dove, Simon L.; Stenkamp, Ronald E.; Mougous, Joseph D.

2012-01-01

399

Dredd,a Novel Effector of the Apoptosis Activators Reaper, Grim,and Hidin Drosophila  

Microsoft Academic Search

Caspases are widely conserved proteases considered to be essential effectors of apoptosis. We identified a novelDrosophilagene,dredd,which shares extensive homology to all members of the caspase gene family. Cells specified for programmed death in development exhibit a striking accumulation ofdreddRNA that requires signaling by the death activators REAPER, GRIM, and HID. Furthermore, directed misexpression of each activator was sufficient to drive

Po Chen; Antony Rodriguez; Robert Erskine; Tien Thach; John M. Abrams

1998-01-01

400

Sustained upregulation of effector natural killer cells in chronic myeloid leukemia after discontinuation of imatinib.  

PubMed

A number of CML patients who achieve a sustained complete molecular response (CMR) for at least 2 years during imatinib (IM) therapy can discontinue IM without relapse. With the long-term goal of developing immunological criteria for managing IM therapy in CML patients, we compared the immunophenotypic profiles of three groups of CML patients: those who received IM and had a CMR for more than two consecutive years (CMR group); patients who received IM and did not have a sustained CMR but maintained a major molecular response for more than 2 years (fluctuating CMR group); and patients with a sustained CMR for more than 6 months after IM discontinuation (STOP-IM group), together with healthy controls. The percentages of effector populations of natural killer (NK) cells, such as interferon (IFN)-?(+) CD3(-) CD56(+) cells, were significantly higher in the STOP-IM and CMR groups than in the fluctuating CMR and control groups. The elevated levels of these effector NK cells were sustained for more than 3 years after IM discontinuation. In contrast, the percentages of effector memory CD8(+) T cells, such as IFN-?(+) CCR7(-) CD45RO(+) CD8(+) cells, were significantly higher in the STOP-IM and control groups than in the CMR and fluctuating CMR groups, possibly owing to IM intake. These results suggest that the immunological activation status of NK cells contributes to CMR maintenance. Higher activation levels of effector NK cells in CML patients being treated with IM might reflect minimization of BCR-ABL1 transcript levels and therefore could be additive information for determining whether to stop IM. PMID:23758044

Mizoguchi, Izuru; Yoshimoto, Takayuki; Katagiri, Seiichiro; Mizuguchi, Junichiro; Tauchi, Tetsuzo; Kimura, Yukihiko; Inokuchi, Koiti; Ohyashiki, Junko H; Ohyashiki, Kazuma

2013-07-09