ライフサイエンスコーパス: VacA

1 VacA also inhibited the proliferation of purified primar

2 VacA blocks IL-2 secretion in transformed T cell lines b

3 VacA can assemble into multiple types of water-soluble f

4 VacA contains two distinct domains, designated p33 and p

5 VacA cytotoxic activity requires assembly of VacA monome

6 VacA genotype s1 m1 was the most prevalent [56.4% (132)]

7 VacA infusion invoked an immune response, as indicated b

8 VacA inhibited activation-induced proliferation of prima

9 VacA inhibited both T cell-induced and PMA/anti-IgM-indu

10 VacA inhibited interleukin-2 (IL-2) production by a muri

11 VacA inhibited the proliferation of primary human T cell

12 VacA inserts into membranes and forms a hexameric, anion

13 VacA is a secreted toxin that plays a role in Helicobact

14 VacA monomers self-assemble into water-soluble oligomeri

15 VacA mutant toxins defective in the capacity to form ani

16 VacA permeabilization induces an influx of extracellular

17 VacA reduced the mitochondrial membrane potential of CD4

18 VacA suppressed HIV infection of T cells at a stage afte

19 VacA treatment inhibits acid secretion by preventing the

20 VacA, by an unknown mechanism, usurps lysosomal and auto

21 VacA-induced clustering and redistribution of late endoc

22 VacA-induced clusters of late endocytic compartments und

23 VacA-induced death of these cells is a caspase-independe

24 VacA-treated Jurkat T cells secreted markedly diminished

25 ilar to that of the full-length Delta6-27p88 VacA protein.

26 panel of C-terminally truncated Delta6-27p88 VacA proteins indicated that a fragment containing amino

27 in lacking amino acids 6 to 27 (Delta6-27p88 VacA) is able to inhibit many activities of wild-type Va

28 Oligomers formed by a VacA s2m1 chimera (which lacks cell-vacuolating activity

29 e p55 structure into a 19-A cryo-EM map of a VacA dodecamer allows us to propose a model for how VacA

30 ve determined low-resolution structures of a VacA dodecamer and heptamer, as well as a 3.8- angstrom

31 Here, we show the existence of a VacA-generated intracellular niche in vivo that protects

32 We have shown previously that a VacA mutant protein lacking amino acids 6 to 27 (Delta6-

33 cytotoxic proteins: Vacuolating cytotoxin A (VacA) and Cytotoxin-Associated gene A (CagA).

34 The vacuolating cytotoxin A (VacA) is both essential and sufficient for inducing mito

35 ts virulence factor vacuolating cytotoxin A (VacA) promotes more severe disease and gastric colonizat

36 orming toxin called vacuolating cytotoxin A (VacA), which contains two domains (p33 and p55) and asse

37 ave been recognized for vacuolating toxin A (VacA) and urease, H. pylori membrane and secreted factor

38 4)Cl, indicating that NH(4)Cl does not alter VacA trafficking to lysosomes or autophagosomes.

39 Among VacA polymorphisms, the intermediate region has recently

40 Moreover, CagA and VacA are polymorphic within different H. pylori strains,

41 ed on the roles of H. pylori toxins CagA and VacA on the disease process and have suggested that both

42 CagA and VacA were associated with a significantly increased risk

43 f two known virulence determinants (CagA and VacA) are highly divergent, with 77% and 87% mean amino

44 VacA to form mixed oligomeric complexes, and VacA Delta346-347 inhibited wild-type vacuolating activi

45 gastric epithelial cells with wild-type and VacA-deficient H. pylori strains, treatment of cells wit

46 rs known to inhibit cellular vacuolation and VacA membrane channel activity also inhibit cytochrome c

47 he efficient induction of Tregs in vivo, and VacA is required to prevent allergen-induced asthma.

48 ding a secreted, pore-forming toxin known as VacA.

49 bilayer and membrane depolarization assays, VacA proteins containing V21L and S25L mutations were de

50 tested the hypothesis that NH(4)Cl augments VacA toxicity by altering the intracellular trafficking

51 there are allele-driven interactions between VacA and CagA.

52 The sharing of such peculiar properties by VacA and host ClC channels, together with their similar

53 of H. pylori virulence factors such as Cag, VacA, and Urease.

54 h isogenic mutants deficient in either CagA, VacA, lipopolysaccharide, or gamma-glutamyl transpeptida

55 unctions of macrophages and dendritic cells, VacA inhibition of T-cell function, and suppressive effe

56 The goal of this study was to characterize VacA-VacA interactions that may mediate assembly of VacA

57 nce of weak bases (e.g., ammonium chloride), VacA induces the formation of large cytoplasmic vacuoles

58 as indicated by the detection of circulating VacA antibodies.

59 ive epithelial cell signaling; the cytotoxin VacA, which causes epithelial damage; and an adhesin, Ba

60 speptidase GGT and the vacuolating cytotoxin VacA, are required and sufficient for asthma protection

61 speptidase GGT and the vacuolating cytotoxin VacA, contribute critically and nonredundantly to H. pyl

62 its pro-apoptotic and vacuolating cytotoxin VacA.

63 cobacter pylori toxin vacuolating cytotoxin (VacA) promotes gastric colonization, and its presence (V

64 The H. pylori vacuolating cytotoxin (VacA) recently has been shown to inhibit stimulation-ind

65 ri secretes an 88-kDa vacuolating cytotoxin (VacA) that may contribute to the pathogenesis of peptic

66 The vacuolating cytotoxin, VacA, is an important virulence factor secreted by the g

67 with and without the vacuolating cytotoxin, VacA, which inhibits human T cell activity.

68 fection by urease and other enzymes, enhance VacA toxicity by inhibiting toxin degradation.

69 In addition, we have examined VacA variants/mutants that differ from wild-type (WT) Va

70 mice that result specifically from extended VacA exposure, we evaluated the efficacy of administerin

71 cs, and may be specific for virulence factor VacA.

72 pylori proteins, including virulence factors VacA and CagA.

73 membrane channel formation is essential for VacA cytotoxicity.

74 two separate domains, as described here for VacA, has rarely been described for pore-forming bacteri

75 mice more efficiently than mutants null for VacA or producing more active forms of it, providing the

76 , including a 60190 isogenic mutant null for VacA, strongly induced interleukin-10 (IL-10) and IL-6 p

77 that amino acids 351 to 360 are required for VacA protein-protein interactions and for dominant-negat

78 tify host cell factors that are required for VacA-induced cell death.

79 an gastric epithelial cells and selected for VacA-resistant clones.

80 Helicobacter pylori secretes a pore-forming VacA toxin that has structural features and activities s

81 rld forms and indicates new genotypes (e.g., VacA m3) involving these loci.

82 To examine how VacA contributes to H. pylori colonization of the mouse

83 decamer allows us to propose a model for how VacA monomers assemble into oligomeric structures capabl

84 However, VacA Delta346-347 did not cause cell vacuolation or memb

85 cause the non-vacuolating phenotype, but if VacA is unblocked, it confers cell line specificity of v

86 nts (bacterial lysate or the immunomodulator VacA) and subsequently subjected them to four different

87 attributable, at least in part, to impaired VacA binding to these cells.

88 In VacA-treated cells containing clustered late endocytic c

89 Proteolysis of ezrin in VacA-infected parietal cells is a novel mechanism underl

90 This led to a marked reduction in VacA protein levels and overall toxin activity.

91 addition of p55 followed by p33 resulted in VacA internalization and cell vacuolation, whereas seque

92 3 and p-55 domains play an important role in VacA assembly into oligomeric structures.

93 y result from strain-dependent variations in VacA structure.

94 In comparison to the individual VacA domains, a mixture of the p33 and p55 proteins exhi

95 Second, H. pylori also induces VacA-independent alteration of mitochondrial replication

96 First, early upon infection VacA induces transient increase of mitochondrial translo

97 At 3 and 30 days of interrupted infusion, VacA was detected in association with gastric glands.

98 n microscopy densities, we have mapped inter-VacA interactions that support oligomerization.

99 Interestingly, VacA Delta346-347 was able to physically interact with w

100 fficking of VacA or inhibiting intracellular VacA degradation.

101 differences in activity, the chimeric m2/m1 VacA protein bound to cells at reduced levels compared t

102 In comparison to the parental m1 VacA protein, a chimeric protein (designated m2/m1) cont

103 55 domain has an important role in mediating VacA binding to cells.

104 in, which has an important role in mediating VacA binding to host cells.

105 the more toxigenic 60190 strain contain more VacA (s1i1 type) than vesicles from the SS1 strain (s2i2

106 lower-shaped oligomeric structures, and most VacA activities are dependent on its capacity to oligome

107 of recombinant VacA and identified 10 mutant VacA proteins that lacked vacuolating cytotoxic activity

108 tion, these are the first examples of mutant VacA proteins that have defects in vacuolating activity

109 Through the analysis of a panel of mutant VacA proteins, we demonstrate that VacA-mediated inhibit

110 d analyzed the properties of purified mutant VacA proteins.

111 dependent on interactions between the mutant VacA proteins and wild-type VacA, and they allow mapping

112 bly, we demonstrate that one of these mutant VacA proteins [VacA-Delta(6-27)] abrogates the immunosup

113 causes death of these cells, whereas mutant VacA proteins defective in membrane channel formation do

114 ial protein synthesis, but not urease, NapA, VacA, CagA, or CagT.

115 e inhibitory properties of dominant-negative VacA mutant proteins are dependent on interactions betwe

116 Mechanistically, neither VacA nor rapamycin inhibited the activation of cytokine

117 We observed VacA colocalization with LAMP1- and LC3-positive vesicle

118 propose that the immunomodulatory actions of VacA on T and B lymphocytes, the major effectors of the

119 This activity of VacA was dependent on its ability to form membrane chann

120 essential for the intracellular activity of VacA, which suggests that this region may constitute a s

121 nnel formation in the biological activity of VacA.

122 Analysis of VacA protein sequences from unrelated H. pylori strains,

123 ter acinonychis reveals that the ancestry of VacA is different from the African origin that typifies

124 cA interactions that may mediate assembly of VacA monomers into higher order structures.

125 VacA cytotoxic activity requires assembly of VacA monomers into oligomeric structures, formation of a

126 main has an important role in the binding of VacA to eukaryotic cell surfaces.

127 report a previously unrecognized capacity of VacA to induce clustering and perinuclear redistribution

128 not completely dependent on, the carriage of VacA.

129 The functional consequences of VacA infection on parietal cell physiology were studied

130 mune cells, but the in vivo contributions of VacA as an important determinant of Hp colonization and

131 VacA i-region is an important determinant of VacA effects on human T cell function.

132 10 mutations mapped within the p33 domain of VacA.

133 The effect of VacA and CagA on the function of this network were simul

134 We investigated the effect of VacA on autophagy in human gastric epithelial cells and

135 We analyzed the effect of VacA on autophagy in peripheral blood monocytes obtained

136 The effect of VacA, CagA, transforming growth factor-beta (TGF-beta),

137 against TRPML1 reversed the toxic effects of VacA on endolysosomal trafficking, culminating in the cl

138 n this study, we investigated the effects of VacA on primary human CD4(+) T cells.

139 In this study, we investigated effects of VacA on the proliferation of various other types of prim

140 on-selective membrane channels, and entry of VacA into host cells.

141 Here, we analyze the molecular evolution of VacA.

142 Notable features of VacA p55 include disruptions in beta-sheet contacts that

143 eria producing the less active s2/i2 form of VacA colonized mice more efficiently than mutants null f

144 nalysis of a nonoligomerizing mutant form of VacA secreted by H. pylori The nonoligomerizing 88-kDa m

145 Interestingly, both forms of VacA bound preferentially to the basolateral surface of

146 Correspondingly, i2 forms of VacA bound to Jurkat cells less avidly than did i1 forms

147 comparison to i1 forms of VacA, i2 forms of VacA had a diminished capacity to inhibit the activation

148 olayers indicated that m1 and m2/m1 forms of VacA had similar cell-vacuolating activities.

149 Type m1 forms of VacA have been extensively studied, but there has been r

150 rains producing more active (s1/i1) forms of VacA is strongly associated with gastric adenocarcinoma.

151 ne effects of different polymorphic forms of VacA on inflammation and metaplasia in the mouse stomach

152 e compared the ability of i1 and i2 forms of VacA to cause functional alterations in Jurkat cells.

153 rences in the capacity of i1 and i2 forms of VacA to cause vacuolation of RK13 cells.

154 pylori strains, including m1 and m2 forms of VacA, allows us to identify structural features of the V

155 In comparison to i1 forms of VacA, i2 forms of VacA had a diminished capacity to inhi

156 urkat cells less avidly than did i1 forms of VacA.

157 ps strikingly similar to the three groups of VacA sequences.

158 istered by oral gavage, extended infusion of VacA did not damage stomach, esophageal, intestinal, or

159 ribute to the binding and internalization of VacA and that both domains are required for vacuolating

160 Introduction of VacA produced a similar response in the apoptosis pathwa

161 ionally, odds of CRC increased with level of VacA antibody in the overall cohort (P = .008) and speci

162 ells were significantly lower than levels of VacA binding to human CD4+ T cells.

163 tometry studies indicated that the levels of VacA binding to primary murine CD4+ T cells were signifi

164 s and provides insight into the mechanism of VacA function.

165 ctivity of parietal cells in the presence of VacA.

166 ides structural insights into the process of VacA oligomerization and identifies regions of VacA prot

167 critical mechanistic step in the process of VacA-induced cell vacuolation.

168 reatment resulted in complete proteolysis of VacA into p-33 and p-55 domains, which remained physical

169 hin the amino-terminal hydrophobic region of VacA are essential for membrane channel formation, and t

170 unique amino-terminal hydrophobic region of VacA, there are three tandem GXXXG motifs (defined by gl

171 cA oligomerization and identifies regions of VacA protomers that are predicted to contact the host ce

172 tly increases the intracellular stability of VacA.

173 ion has shaped the phylogenetic structure of VacA and CagA, and each of these virulence determinants

174 reconstructions indicate the subdivision of VacA sequences into three main groups with distinct geog

175 heptamer formation, and identify surfaces of VacA that likely contact membrane.

176 Identifying the host cell targets of VacA could be useful for elucidating the HIV life cycle

177 ic region located near the amino terminus of VacA.

178 by altering the intracellular trafficking of VacA or inhibiting intracellular VacA degradation.

179 Two main types of VacA, m1 and m2, can be distinguished by phylogenetic an

180 hese foundational studies support the use of VacA infusion for identifying gastric alterations that a

181 e that the assembly of functional oligomeric VacA complexes is dependent on specific sequences, inclu

182 main involved in the formation of oligomeric VacA complexes.

183 enic H. pylori mutants lacking either GGT or VacA are incapable of preventing LPS-induced DC maturati

184 dependent of the cag pathogenicity island or VacA.

185 rminal portion (p55 domain) of wild-type p88 VacA could complement either Delta6-27p33 or Delta(6-27/

186 ein physically interacted with wild-type p88 VacA, whereas the Delta6-27p33 protein did not.

187 otes gastric colonization, and its presence (VacA(+)) is associated with more-severe disease.

188 rate that one of these mutant VacA proteins [VacA-Delta(6-27)] abrogates the immunosuppressive action

189 We observed that purified VacA has relatively little effect on the viability of AG

190 ri strains, treatment of cells with purified VacA proteins and infection of a mouse model, we show th

191 VacA fragments corresponding to two putative VacA domains (designated p33 and p55).

192 The Treg skewing was independent of H pylori VacA and CagA and dependent on TGF-beta and IL-10.

193 ns, we found serologic responses to H pylori VacA to associate with increased risk of CRC risk, parti

194 H pylori VacA-specific seropositivity was associated with an 11%

195 Helicobacter pylori VacA is a pore-forming toxin that causes multiple altera

196 Helicobacter pylori VacA is a secreted pore-forming toxin that induces cell

197 Helicobacter pylori VacA is a secreted pore-forming toxin that is comprised

198 Helicobacter pylori VacA is a secreted protein toxin that may contribute to

199 The Helicobacter pylori VacA toxin is an 88-kDa secreted protein that causes mul

200 Helicobacter pylori VacA, a pore-forming toxin secreted by an autotransporte

201 In contrast to rapamycin, VacA did not suppress phosphorylation of p70 S6 kinase b

202 essing randomly mutated forms of recombinant VacA and identified 10 mutant VacA proteins that lacked

203 zed the functional properties of recombinant VacA fragments corresponding to two putative VacA domain

204 As a result, VacA can perturb, but not necessarily abolish, the homeo

205 t engineering the SS1 strain to produce s1i1 VacA did not increase the toxin content of its vesicles.

206 ype) than vesicles from the SS1 strain (s2i2 VacA), but engineering the SS1 strain to produce s1i1 Va

207 Helicobacter pylori (Hp) secrete VacA, a diffusible pore-forming exotoxin that is epidemi

208 The 88-kDa secreted VacA protein can undergo limited proteolysis to yield tw

209 n strains producing m2 forms of the secreted VacA toxin and propose that these functionally interacti

210 The secreted VacA toxin is an important H. pylori virulence factor th

211 In contrast, a shorter VacA fragment lacking amino acids 6 to 27 (Delta6-27p33)

212 ined the three-dimensional structures of six VacA oligomeric conformations at ~15-A resolution.

213 of mutant VacA proteins, we demonstrate that VacA-mediated inhibition of T cell proliferation require

214 We show here that VacA suppresses IL-2-induced cell-cycle progression and

215 Our results indicate that VacA disrupts the apical membrane-cytoskeletal interacti

216 These results indicate that VacA induces gastric epithelial cell apoptosis and sugge

217 In vitro studies indicate that VacA modulates gastric epithelial and immune cells, but

218 scence microscopy experiments indicated that VacA did not colocalize with Cx43.

219 f CD4(+) T cells or B cells, indicating that VacA does not alter early signaling events required for

220 We propose that VacA augments H. pylori-induced mucosal inflammation in

221 Furthermore, we report that VacA targets the lysosomal calcium channel TRPML1 to dis

222 ectron microscopic examination revealed that VacA treatment disrupts the radial arrangement of actin

223 (generated using CRISPR/Cas9), we show that VacA degradation is independent of autophagy and proteas

224 These analyses show that VacA p88 consists predominantly of a right-handed beta-h

225 Here we show that VacA permeabilizes the apical membrane of gastric pariet

226 We speculate that VacA-induced alterations in late endocytic membrane traf

227 programmed necrosis pathway and suggest that VacA can be included among the growing number of bacteri

228 These results suggest that VacA inhibits T-cell activation and HIV infection via a

229 We suggest that VacA may inhibit the clonal expansion of T cells that ha

230 orming bacterial toxins, which suggests that VacA is a pore-forming toxin with unique structural prop

231 Among the VacA-resistant clones, we identified multiple gene trap

232 oduce alterations in the region encoding the VacA i-region.

233 By fitting the VacA p55 crystal structure into the electron microscopy

234 onal correlates of sequence variation in the VacA midregion (m region).

235 Furthermore, internalization of the VacA domains was detected when cells were incubated with

236 as well as a 3.8- angstrom structure of the VacA hexamer.

237 n relatively little study of the role of the VacA intermediate region (i-region) in toxin activity.

238 y, these data help explain the impact of the VacA intermediate region on disease and lead to the hypo

239 we present a 2.4-A crystal structure of the VacA p55 domain, which has an important role in mediatin

240 uggest that, similar to the secretion of the VacA passenger domain, the N-terminal domains of proteas

241 Here we present a structural model of the VacA pore that strongly resembles the structure of an un

242 By providing the most detailed view of the VacA structure to date, these data offer new insights in

243 ws us to identify structural features of the VacA surface that may be important for interactions with

244 Further, rooting the VacA tree with outgroup sequences from the close relativ

245 Here we show that the VacA channel exhibits two of the most characteristic ele

246 These results indicate that the VacA i-region is an important determinant of VacA effect

247 Here we demonstrate that the VacA toxin produced by Helicobacter pylori can inhibit H

248 Further experiments indicated that the VacA-induced inhibition of primary human T cell prolifer

249 Similar to wild-type VacA, the VacA Delta346-347 mutant protein was proteolytically pro

250 novel mechanism of toxin action in which the VacA pore largely mimics the electrophysiological behavi

251 T cell proliferation was not attributable to VacA effects on NFAT activation or IL-2 secretion.

252 epithelial cells and mouse gastric cells to VacA disrupted induction of autophagy in response to the

253 resistance of primary murine CD4+ T cells to VacA is attributable, at least in part, to impaired VacA

254 nhances the susceptibility of these cells to VacA-induced vacuolation and cell death.

255 In contrast to VacA-induced cell vacuolation, VacA-induced clustering a

256 a host cell constituent that contributes to VacA-induced cell death and that variation among cell ty

257 We previously found that limited exposure to VacA induces autophagy of gastric cells, which eliminate

258 in Cx43 expression results in resistance to VacA-induced cell death.

259 educed induction of autophagy in response to VacA(+) compared to cells from individuals that did not

260 acA (predicted to be structurally similar to VacA membrane channels) reveals that p55 and the beta-he

261 iation among cell types in susceptibility to VacA-induced cell death is attributable at least in part

262 her murine T lymphocytes were susceptible to VacA activity.

263 c epithelial cells are highly susceptible to VacA-induced cell death.

264 y, AZ-521 cells were the most susceptible to VacA-induced cell death.

265 cells, the cells became more susceptible to VacA.

266 Remarkably, H. pylori that lack toxigenic VacA colonize enlarged dysfunctional lysosomes in the ga

267 ssues from patients infected with toxigenic (VacA(+)) or nontoxigenic strains.

268 The secreted pore-forming toxin VacA is one of the major virulence factors of H. pylori.

269 s against infection with H pylori; the toxin VacA disrupts autophagy to promote infection, which coul

270 ic mucosa and secretes a pore-forming toxin (VacA).

271 reted Helicobacter pylori vacuolating toxin (VacA) inhibits the activation of T cells.

272 Helicobacter pylori vacuolating toxin (VacA) is a secreted toxin that is reported to produce mu

273 Vacuolating toxin (VacA) is crucial in facilitating the colonization of the

274 forming exotoxin known as vacuolating toxin (VacA).

275 H. pylori secretes a toxin, VacA, that targets human gastric epithelial cells and T

276 hanism by producing the pro-apoptotic toxin, VacA, which was recently demonstrated to (i) localize to

277 the Helicobacter pylori pore-forming toxin, VacA, does not appear to function by either of these mec

278 A secreted H. pylori toxin, VacA, can cause multiple alterations in gastric epitheli

279 croscopy map of hexamers formed by wild-type VacA (predicted to be structurally similar to VacA membr

280 Wild-type VacA causes death of these cells, whereas mutant VacA pr

281 s the immunosuppressive actions of wild-type VacA in a dominant-negative fashion.

282 able to inhibit many activities of wild-type VacA in a dominant-negative manner.

283 Incubation of AZ-521 cells with wild-type VacA results in cell swelling, poly(ADP-ribose) polymera

284 s able to physically interact with wild-type VacA to form mixed oligomeric complexes, and VacA Delta3

285 tween the mutant VacA proteins and wild-type VacA, and they allow mapping of a domain involved in the

286 Similar to wild-type VacA, the VacA Delta346-347 mutant protein was proteolyt

287 nel activities similar to those of wild-type VacA.

288 n contrast to VacA-induced cell vacuolation, VacA-induced clustering and redistribution of late endoc

289 These events occur when VacA is not detected intracellularly, therefore do not r

290 terminal portion of p33 is unstructured when VacA is in a monomeric form and that it undergoes a conf

291 IL-2 compared with untreated cells, whereas VacA-treated primary human T cells continued to secrete

292 The exact mechanisms by which VacA contributes to infection are unclear.

293 hese experiments mimics the process by which VacA oligomerizes when in contact with membranes of host

294 strains producing chimeric proteins in which VacA m1 segments of a parental strain were replaced by c

295 c biopsy samples from patients infected with VacA(+), but not nontoxigenic strains of H pylori, had i

296 ection were detected in animals infused with VacA, including reduction of the gastric mucus layer, an

297 Intoxication with VacA did not alter the magnitude of calcium flux that oc

298 Intoxication of PBMC with VacA inhibited the stimulation-induced proliferation of

299 of Drp1-induced mitochondrial fission within VacA-intoxicated cells inhibited the activation of the p

300 ants/mutants that differ from wild-type (WT) VacA in toxin activity and/or oligomeric structural feat