Proinflammatory gene expression in mouse ST2 cell line in response to infection by Porphyromonas gingivalis

Porphyromonas gingivalis is a predominant periodontal pathogen, whose infection causes inflammatory responses in periodontal tissue and alveolar bone resorption. Various virulence factors of this pathogen modulate host innate immune responses. It has been reported that gingipains degrade a wide variety of host cell proteins, and fimbriae are involved in bacterial adhesion to and invasion of host cells. In the present study, we profiled ST2 stromal cell gene expression following infection with the viable P. gingivalis strain ATCC33277 as well as with its gingipain- and fimbriae-deficient mutants, using microarray technology and quantitative real-time polymerase chain reaction. Using a mouse array of about 20,000 genes, we found that infection with the wild strain elicited a significant upregulation (greater than 2-fold) of expression of about 360 genes in ST2 cells, which included the chemokines CCL2, CCL5, and CXCL10, and other proinflammatory proteins such as interleukin-6 (IL-6) and matrix metalloproteinase-13 (MMP-13). Further, infection with the gingipain-deficient mutant elicited a reduced expression of the CXCL10, IL-6 and MMP-13 genes, suggesting that gingipains play an important role in inducing the expression of those genes following P. gingivalis infection. On the other hand, the pattern of global gene expression induced by the fimbriae-deficient mutant was similar to that by the wild strain. These results suggest that P. gingivalis infection induces gene expression of a wide variety of proinflammatory proteins in stromal cells/osteoblasts, and gingipains may be involved in inducing several of the proinflammatory factors.     

Ehrlichia subversion of host innate responses

Anaplasma (formerly Ehrlichia) phagocytophilum and Ehrlichia chaffeensis, upon infection of humans, replicate in host leukocyte granulocytes and monocytes/macrophages, respectively. These unusual Gram-negative bacteria lack genes for biosynthesis of the lipopolysaccharide and peptidoglycan that activate host leukocytes. Caveolae-mediated endocytosis directs A. phagocytophilum and E. chaffeensis to an intracellular compartment secluded from oxygen-dependent and -independent killing. Furthermore, these bacteria orchestrate a remarkable series of events that culminate in suppression of NADPH oxidase, phagocyte activation and differentiation pathways, apoptosis, and interferon-gamma signaling in host leukocytes. They offer a fascinating example of how pathogens employ intricate strategies to usurp and subvert host cell function.     

Proteomics-based analysis of a counter-oxidative stress system in Porphyromonas gingivalis

Porphyromonas gingivalis is a Gram-negative anaerobic pathogen associated with chronic periodontitis. Although anaerobic, P. gingivalis exhibits a high degree of aerotolerance, which enables it to survive within periodontal pockets. The aim of the present study was to examine the effect of oxidative stress on protein expression in P. gingivalis to obtain a better understanding of the mechanism underlying its aerotolerance. To accomplish this, P. gingivalis cells were grown under conditions of hemin limitation (0.01 microg/mL) to avoid the oxygen protective effect of hemin on oxidative stress. The proteins were then extracted from cultures either left untreated or subjected to oxidative stress and separated by 2-DE. The resultant protein expression profiles were examined by image scanning, and those found to differ depending on the presence or absence of aeration were subjected to MALDI-MS and then analyzed using the ORF database of P. gingivalis W83 from The Institute of Genomic Research. Oxidative stress was found to affect the expression of numerous proteins in P. gingivalis cells. In particular, the levels of HtpG, GroEL, DnaK, AhpC, TPR domain protein, and trigger factor were substantially increased.     

Queen-queen competition by precocious male production in multiqueen ant colonies

Arriving earlier in the breeding area than his rivals may be beneficial for a male when females mate only once or during a short time span. The timing of a male's entrance is usually determined by the male himself, e.g., through returning early from his winter quarters or through accelerated larval development . Here, we document a surprisingly simple way of "first come, first served" in a species with local mate competition. In multiqueen colonies of a Cardiocondyla ant, mother queens make sure that their own sons are the first to monopolize mating with a large harem of female sexuals by producing extremely long-lived males early in colony life. Whereas queens in newly founded single-queen colonies started to produce male and female sexuals only several weeks after the eclosion of their first worker offspring, queens in multiqueen colonies precociously reared sons long before the first female sexuals and even before the emergence of their first workers. These early males killed all later emerging males in the nest and mated with all female sexuals subsequently produced. Our data document that the patterns of growth and productivity of insect colonies are surprisingly flexible and can be turned upside down under appropriate selection pressures.     

N-acetyl-d-glucosamine induces the expression of multidrug exporter genes, mdtEF, via catabolite activation in Escherichia coli

The expression of MdtEF, a multidrug exporter in Escherichia coli, is positively controlled through multiple signaling pathways, but little is known about signals that induce MdtEF expression. In this study, we investigated compounds that induce the expression of the mdtEF genes and found that out of 20 drug exporter genes in E. coli, the expression of mdtEF is greatly induced by N-acetyl-d-glucosamine (GlcNAc). The induction of mdtEF by GlcNAc is not mediated by the evgSA, ydeO, gadX, and rpoS signaling pathways that have been known to regulate mdtEF expression. On the other hand, deletion of the nagE gene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction of mdtEF by GlcNAc was also greatly inhibited by the addition of cyclic AMP (cAMP) and completely abolished upon deletion of the cAMP receptor protein gene (crp). Other PTS sugars, glucose and d-glucosamine, also induced mdtEF gene expression. These results suggest that mdtEF expression is stimulated through catabolite control.     

Highly oligomeric procyanidins ameliorate experimental autoimmune encephalomyelitis via suppression of Th1 immunity

Extracts of Jatoba, a South American herb, when injected i.p. into a mouse model of experimental autoimmune encephalomyelitis (EAE), inhibited the aggravation of clinical symptoms. At the same time, production of myelin oligodendrocyte glycoprotein Ag-specific IFN-gamma and TNF-alpha by spleen cells was markedly suppressed. After administration of Jatoba there was minimal evidence of the demyelination that is characteristic of the EAE model. Decreases in clinical scores were observed when Jatoba extracts were injected just before Ag. The purified active compounds are likely to be polyphenols that are absorbable to polyvinylpolypyrrolidone. The active compounds were polymerized polyphenol polymers (procyanidins) and at least five degrees of polymerization were necessary for activity. In addition, extracts of other plant materials containing such procyanidins had similar activity. After administration of highly polymerized procyanidins, there was a decrease in both dendritic and CD4(+) T cells. Although macrophages were increased in number, the expression of CD80 and MHC class II molecules was depressed indicating that the macrophages were immature. The results indicate that the suppression of development of EAE by the highly polymerized procyanidins resulted from an inhibition of Th1 and the effects might be associated with depression of Ag-presenting capability.     

Serodiagnostic potential of chemically synthesized glycosphingolipid antigens in an enzyme-linked immunosorbent assay for alveolar echinococcosis

In the serodiagnosis of alveolar echinococcosis, the detection of specific reactions against not only protein but also carbohydrate antigen is useful and both antigens supplement each other. Though recombinant protein antigens have recently advanced, the preparation of carbohydrate antigen still depends on extraction from crude antigens. In the latter case, it is not conventional to obtain carbohydrate antigen as a single component for examination and research. Therefore, chemically synthesized carbohydrate antigens were prepared for serodiagnosis by the enzyme-linked immunosorbent assay (ELISA). Four antigens with the structure of glycosphingolipids from Echinococcus multilocularis were examined and one antigen, Galbeta1-6(Fucalpha1-3)Galbeta1-6Galbeta1-ceramide, was found to show significant serodiagnostic potential in differentiating alveolar from cystic echinococcosis.     

Loss of heterozygosity in yeast can occur by ultraviolet irradiation during the S phase of the cell cycle

A CAN1/can1Δ heterozygous allele that determines loss of heterozygosity (LOH) was used to study recombination in Saccharomyces cerevisiae cells exposed to ultraviolet (UV) light at different points in the cell cycle. With this allele, recombination events can be detected as canavanine-resistant mutations after exposure of cells to UV radiation, since a significant fraction of LOH events appear to arise from recombination between homologous chromosomes. The radiation caused a higher level of LOH in cells that were in the S phase of the cell cycle relative to either cells at other points in the cell cycle or unsynchronized cells. In contrast, the inactivation of nucleotide excision repair abolished the cell cycle-specific induction by UV of LOH. We hypothesize that DNA lesions, if not repaired, were converted into double-strand breaks during stalled replication and these breaks could be repaired through recombination using a non-sister chromatid and probably also the sister chromatid. We argue that LOH may be an outcome used by yeast cells to recover from stalled replication at a lesion.     

AtVPS29, a putative component of a retromer complex, is required for the efficient sorting of seed storage proteins

Seed storage proteins are synthesized on rough endoplasmic reticulum (ER) as larger precursors and are sorted to protein storage vacuoles, where they are converted into the mature forms. We report here an Arabidopsis mutant, maigo 1 (mag1), which abnormally accumulates the precursors of two major storage proteins, 12S globulin and 2S albumin, in dry seeds. Electron microscopy revealed that mag1 seeds mis-sort storage proteins by secreting them from cells. mag1 seeds have smaller protein storage vacuoles in the seeds than do wild-type seeds. The MAG1 gene encodes a homolog of the yeast (Saccharomyces cerevisiae) protein VPS29. VPS29 is a component of a retromer complex for recycling a vacuolar sorting receptor VPS10 from the pre-vacuolar compartment to the Golgi complex. Our findings suggest that MAG1/AtVPS29 protein is involved in recycling a plant receptor for the efficient sorting of seed storage proteins. The mag1 mutant exhibits a dwarf phenotype. A plant retromer complex plays a significant role in plant growth and development.