Role In Chemotaxis Research Articles

Chemokine receptor CCR7 induces intracellular signaling that inhibits apoptosis of mature dendritic cells

AbstractAcquisition of CCR7 expression is an important phenotype change during dendritic cell (DC) maturation that endows these cells with the capability to migrate to lymph nodes. We have analyzed the possible role of CCR7 on the regulation of the survival of DCs. Stimulation with CCR7 ligands CCL19 and CCL21 inhibits apoptotic hallmarks of serum-deprived DCs, including membrane phosphatidylserine exposure, loss of mitochondria membrane potential, increased membrane blebs, and nuclear changes. Both chemokines induced a rapid activation of phosphatidylinositol 3′-kinase/Akt1 (PI3K/Akt1), with a prolonged and persistent activation of Akt1. Interference with PI3K, Gi, or G protein βγ subunits abrogated the effects of the chemokines on Akt1 activation and on survival. In contrast, inhibition of extracellular signal-related kinase 1/2 (Erk1/2), p38, or c-Jun N-terminal kinase (JNK) was ineffective. Nuclear factor–κB (NFκB) was involved in the antiapoptotic effects of chemokines because inhibition of NFκB blunted the effects of CCL19 and CCL21 on survival. Furthermore, chemokines induced down-regulation of the NFκB inhibitor IκB, an increase of NFκB DNA-binding capability, and translocation of the NFκB subunit p65 to the nucleus. In summary, in addition to its well-established role in chemotaxis, we show that CCR7 also induces antiapoptotic signaling in mature DCs.

The attachment process and physiological properties of Escherichia coli O157:H7 on quartz

BackgroundManure application and sewage irrigation release many intestinal pathogens into the soil. After being introduced into the soil matrix, pathogens are commonly found to attach to soil minerals. Although the survival of mineral-associated Escherichia coli O157:H7 has been studied, a comprehensive understanding of the attachment process and physiological properties after attachment is still lacking.ResultsIn this study, planktonic and attached Escherichia coli O157:H7 cells on quartz were investigated using RNA sequencing (RNA-seq) and the isobaric tagging for relative and absolute quantitation (iTRAQ) proteomic method. Based on the transcriptomic and proteomic analyses and gene knockouts, functional two-component system pathways were required for efficient attachment; chemotaxis and the Rcs system were identified to play determinant roles in E. coli O157:H7 attachment on quartz. After attachment, the pyruvate catabolic pathway shifted from the tricarboxylic acid (TCA) cycle toward the fermentative route. The survival rate of attached E. coli O157:H7 increased more than 10-fold under penicillin and vancomycin stress and doubled under alkaline pH and ferric iron stress.ConclusionsThese results contribute to the understanding of the roles of chemotaxis and the Rcs system in the attachment process of pathogens and indicate that the attachment of pathogens to minerals significantly elevates their resistance to antibiotics and environmental stress, which may pose a potential threat to public health.

Angiogenesis and vessel co-option in a mathematical model of diffusive tumor growth: The role of chemotaxis

This work considers the propagation of a tumor from the stage of a small avascular sphere in a host tissue and the progressive onset of a tumor neovasculature stimulated by a pro-angiogenic factor secreted by hypoxic cells. The way new vessels are formed involves cell sprouting from pre-existing vessels and following a trail via a chemotactic mechanism (CM). Namely, it is first proposed a detailed general family of models of the CM, based on a statistical mechanics approach. The key hypothesis is that the CM is composed by two components: i) the well–known bias induced by the angiogenic factor gradient; ii) the presence of stochastic changes of the velocity direction, thus giving rise to a diffusive component. Then, some further assumptions and simplifications are applied in order to derive a specific model to be used in the simulations. The tumor progression is favored by its acidic aggression towards the healthy cells. The model includes the evolution of many biological and chemical species. Numerical simulations show the onset of a traveling wave eventually replacing the host tissue with a fully vascularized tumor. The results of simulations agree with experimental measures of the vasculature density in tumors, even in the case of particularly hypoxic tumors.

Abstract 2829: A novel candidate for immunotherapy mediating the balance between the immune system and cancer

Abstract Cytotoxic CD8+ T cells are considered as one of the main populations of effector immune cells in antitumor immunity. The absence of CD8+ T cells in the central tumor area has become a major obstacle for solid tumor immunotherapy. Thus, novel therapeutic strategies that could promote CD8+ T cells to accumulate in the central tumor area are urgently needed. To this aim, we want to propose a novel candidate INGM01 a highly glycosylated mucin-like protein localized on the cell surface and so far poorly characterized. High INGM01 expression is reported to be associated to a higher survival rate in some cancers (PreCOG database). We found that INGM01 is physiologically expressed on the surface of different cancer human cell lines and its over-expression by cDNA transfection significantly increased motility and migration phenotypes, such as improved scratch recovery in the wound healing assay, altered cytoskeleton organization with loss of actin branches, reduced E-cadherin expression and activated Fak pathway through phosphorylation of its Y925. We also found that INGM01 is specifically over-expressed in tumor-infiltrating CD8+ and CD4+ lymphocytes, as judged by IHC and IF analysis of cryopreserved tissues and by FACS analysis of T cells isolated from different cancers (e.g. colon, kidney), while it is marginally expressed in T-cells resident in adjacent normal tissues. Microscopy analysis showed that INGM01 localizes in anchoring sites of CD8+ T-cells attacking the cancer cells forming a cluster of lymphocytes on their surface. INGM01 expression in T lymphocyte is significantly induced by CD3/CD28 receptor activation and by the microenvironmental milieu conditioned by cancer cells, through the production of soluble factors. Indeed, INGM01 is localized in the uropod of both CD3/28 activated and ex vivo isolated tumor infiltrating CD4+ and CD8+ T cells confirming a role of INGM01 in motility of the T-cells. We found INGM01 co-expressed with other uropod-associated proteins, such as ICAM-I, LFA-1 and CXCR-3, involved in the acquisition of the polarity needed for T-cell chemotaxis and for migration. By Boyden chamber, with and without a HUVEC cell monolayer, we found that INGM01 positive CD8+ and Jurkat cells migrate towards wells containing conditioned medium of cancer cells and this process is significantly impaired by INGM01 silencing indicating its role in chemotaxis and trans-endothelial migration. Furthermore, INGM01 contributes to the cytotoxic function of CD8+ T-cells, since its silencing causes a reduction of expression of Th1 effector cytokines, such as IFN-γ, TNFα. Our hypothesis is that, after a deeper analysis of the interaction/s and ligand/s involving INGM01, it might be possible to generate affinity agents or bi-spefic antibodies able to enhance the intratumoral infiltration of cytotoxic CD8+ T-cells expressing INGM01 and their migration towards cancer cells, to promote their killing. Citation Format: Elisa Pesce, Chiara Cordiglieri, Cristina Manara, Stefania Oliveto, Susanna Campagnoli, Tiziano Donnarumma, Manuele Martinelli, Mariacristina Crosti, Elisa De Camilli, Stefano Biffo, Sergio Abrignani, Mauro Bombaci, Renata Maria Grifantini, Andrea Gobbini. A novel candidate for immunotherapy mediating the balance between the immune system and cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2829.

Specific Root Exudate Compounds Sensed by Dedicated Chemoreceptors Shape Azospirillum brasilense Chemotaxis in the Rhizosphere.

Plant roots shape the rhizosphere community by secreting compounds that recruit diverse bacteria. Colonization of various plant roots by the motile alphaproteobacterium Azospirillum brasilense causes increased plant growth, root volume, and crop yield. Bacterial chemotaxis in this and other motile soil bacteria is critical for competitive colonization of the root surfaces. The role of chemotaxis in root surface colonization has previously been established by endpoint analyses of bacterial colonization levels detected a few hours to days after inoculation. More recently, microfluidic devices have been used to study plant-microbe interactions, but these devices are size limited. Here, we use a novel slide-in chamber that allows real-time monitoring of plant-microbe interactions using agriculturally relevant seedlings to characterize how bacterial chemotaxis mediates plant root surface colonization during the association of A. brasilense with Triticum aestivum (wheat) and Medicago sativa (alfalfa) seedlings. We track A. brasilense accumulation in the rhizosphere and on the root surfaces of wheat and alfalfa. A. brasilense motile cells display distinct chemotaxis behaviors in different regions of the roots, including attractant and repellent responses that ultimately drive surface colonization patterns. We also combine these observations with real-time analyses of behaviors of wild-type and mutant strains to link chemotaxis responses to distinct chemicals identified in root exudates to specific chemoreceptors that together explain the chemotactic response of motile cells in different regions of the roots. Furthermore, the bacterial second messenger c-di-GMP modulates these chemotaxis responses. Together, these findings illustrate dynamic bacterial chemotaxis responses to rhizosphere gradients that guide root surface colonization.IMPORTANCE Plant root exudates play critical roles in shaping rhizosphere microbial communities, and the ability of motile bacteria to respond to these gradients mediates competitive colonization of root surfaces. Root exudates are complex chemical mixtures that are spatially and temporally dynamic. Identifying the exact chemical(s) that mediates the recruitment of soil bacteria to specific regions of the roots is thus challenging. Here, we connect patterns of bacterial chemotaxis responses and sensing by chemoreceptors to chemicals found in root exudate gradients and identify key chemical signals that shape root surface colonization in different plants and regions of the roots.

CheY1 and CheY2 of Azorhizobium caulinodans ORS571 Regulate Chemotaxis and Competitive Colonization with the Host Plant.

The genome of Azorhizobium caulinodans ORS571 encodes two chemotaxis response regulators: CheY1 and CheY2. cheY1 is located in a chemotaxis cluster (cheAWY1BR), while cheY2 is located 37 kb upstream of the cheAWY1BR cluster. To determine the contributions of CheY1 and CheY2, we compared the wild type (WT) and mutants in the free-living state and in symbiosis with the host Sesbania rostrata Swim plate tests and capillary assays revealed that both CheY1 and CheY2 play roles in chemotaxis, with CheY2 having a more prominent role than CheY1. In an analysis of the swimming paths of free-swimming cells, the ΔcheY1 mutant exhibited decreased frequency of direction reversal, whereas the ΔcheY2 mutant appeared to change direction much more frequently than the WT. Exopolysaccharide (EPS) production in the ΔcheY1 and ΔcheY2 mutants was lower than that in the WT, but the ΔcheY2 mutant had more obvious EPS defects that were similar to those of the ΔcheY1 ΔcheY2 and Δeps1 mutants. During symbiosis, the levels of competitiveness for root colonization and nodule occupation of ΔcheY1 and ΔcheY2 mutants were impaired compared to those of the WT. Moreover, the competitive colonization ability of the ΔcheY2 mutant was severely impaired compared to that of the ΔcheY1 mutant. Taken together, the ΔcheY2 phenotypes are more severe than the ΔcheY1 phenotype in free-living and symbiotic states, and that of the double mutant resembles the ΔcheY2 single-mutant phenotype. These defects of ΔcheY1 and ΔcheY2 mutants were restored to the WT phenotype by complementation. These results suggest that there are different regulatory mechanisms of CheY1 and CheY2 and that CheY2 is a key chemotaxis regulator under free-living and symbiosis conditions.IMPORTANCEAzorhizobium caulinodans ORS571 is a motile soil bacterium that has the dual capacity to fix nitrogen both under free-living conditions and in symbiosis with Sesbania rostrata, forming nitrogen-fixing root and stem nodules. Bacterial chemotaxis to chemoattractants derived from host roots promotes infection and subsequent nodule formation by directing rhizobia to appropriate sites of infection. In this work, we identified and demonstrated that CheY2, a chemotactic response regulator encoded by a gene outside the chemotaxis cluster, is required for chemotaxis and multiple other cell phenotypes. CheY1, encoded by a gene in the chemotaxis cluster, also plays a role in chemotaxis. Two response regulators mediate bacterial chemotaxis and motility in different ways. This work extends the understanding of the role of multiple response regulators in Gram-negative bacteria.

MON-504 VEGFA and VEGFR2 Expression in Different Histological Types of Thyroid Nodules: Could Immunohistochemistry Have a Clinical Utility?

Vascular endothelial growth factors (VEGFs) are a family of proteins involved in several elements that play an important role in the development of blood vessels. Besides acting in angiogenesis, VEGFA has important roles in chemotaxis, for macrophages and granulocytes, and vasodilation. VEGFA binds to VEGFR2, that acts on the MAPK and PI3K pathways, fundamental pathways for thyroid carcinogenesis. In order to assess the expression of VEGFA and VEGFR2, in different thyroid nodules, we used a Tissue MicroArray including 91 benign (74 females, 16 males, 49.84±12.65years old) and 125 malignant thyroid nodules (97 females, 28 males, 46.57±14.87 years old). Clinical and pathology data were obtained from 47 goiters; 43 follicular adenomas (FA) and a total of 104 papillary thyroid carcinomas (PTC), including 35 classic papillary thyroid carcinomas (CPTC), 30 follicular variant of PTC (FVPTC), 25 oxifilic variant of PTC (OVPTC), 14 tall cell papillary thyroid carcinomas (TCPTC); and 21 follicular thyroid carcinomas (FTC). All patients were managed according to a standard protocol based on current guidelines and followed-up for 116.9±70.8 months. VEGFA protein expression did not differentiate benign from malignant thyroid nodules. However, VEGFA was more frequently expressed in the less differentiated thyroid tissues. In fact, 95.8% of the FTC had positive expression. On the contrary, the intensity of this protein expression was progressively lower according to the process of cellular dedifferentiation (Goiter: 21.4%; FA: 16.3%; PTC: 8.7% and FTC: 0.0%; x2 = 0.031). There was no difference in VEGFR2 expression between malignant and benign nodules (x2= 0.108), but this protein showed more intense expression in tissues that also presented Hürthle cells (x2 <0.0001). We were not able to find any correlation, neither of VEGFA nor with VEGFR2 expression, and any other feature of aggressiveness, including invasion, metastasis, lymph node metastasis, and distant metastasis. We conclude that VEGFA and VEGFR2 expression may help identify less differentiated tumors and the analysis of a larger cohort may prove the clinical utility of these markers.

Assigning a role for chemosensory signal transduction in Campylobacter jejuni biofilms using a combined omics approach

Biofilms of the gastroenteric pathogen C. jejuni may serve an important role in the transmission of infection from reservoirs of infection to humans. Herein, we undertook a combinatorial approach examining differential gene expression and protein abundance during biofilm formation in C. jejuni. Biofilms induced a substantial rearrangement of the C. jejuni transcriptome and proteome, with ~600 genes differentially expressed when compared to planktonic cells. Genes and proteins induced in biofilms were involved in iron metabolism and acquisition, cell division, glycan production and attachment, while those repressed were associated with metabolism, amino acid usage, and large tracts of the chemotaxis pathway. We further examined the role of chemotaxis in C. jejuni biofilm formation by examining isogenic strains with deletions of the cheV and cheW signal transduction genes. Both ∆cheV and ∆cheW exhibited a significant decrease in directed motility when compared to wild-type C. jejuni as well as demonstrating an increase in autoagglutination ability and biofilm formation. A subtle difference was also observed between the phenotypes of ∆cheV and ∆cheW mutants, both in motility and biofilm formation. This suggests roles for CheV and CheW and may present signal transduction as a potential method for modulating C. jejuni biofilm formation.

Effects of Halophyte Root Exudates and Their Components on Chemotaxis, Biofilm Formation and Colonization of the Halophilic Bacterium Halomonas Anticariensis FP35T.

Increase in soil salinity poses an enormous problem for agriculture and highlights the need for sustainable crop production solutions. Plant growth-promoting bacteria can be used to boost the growth of halophytes in saline soils. Salicornia is considered to be a promising salt-accumulating halophyte for capturing large amounts of carbon from the atmosphere. In addition, colonization and chemotaxis could play an important role in Salicornia-microbe interactions. In this study, the role of chemotaxis in the colonization of the halophilic siredophore-producing bacteria, Halomonas anticariensis FP35T, on Salicornia hispanica plants was investigated. The chemotactic response of FP35T to Salicornia root exudates showed optimum dependence at a salt concentration of 5 % NaCl (w/v). Oleanolic acid, the predominant compound in the exudates detected by HPLC and identified by UPLC-HRMS Q-TOF, acts as a chemoattractant. In vitro experiments demonstrated the enhanced positive effects of wild-type H. anticariensis strain FP35T on root length, shoot length, germination and the vigour index of S. hispanica. Furthermore, these positive effects partially depend on an active chemotaxis system, as the chemotaxis mutant H. anticariensis FP35 ΔcheA showed reduced plant growth promotion for all the parameters tested. Overall, our results suggest that chemotaxis responses to root exudates play an important role in interactions between Salicornia and halophilic bacteria, enhance their colonization and boost plant growth promotion. Preliminary results also indicate that root exudates have a positive impact on H. anticariensis FP35T biofilm formation under saline conditions, an effect which totally depends on the presence of the cheA gene.

Metabolomics as an Approach to Characterise the Contrasting Roles of CCR5 in the Presence and Absence of Disease.

Chemokine receptors such as C-C chemokine receptor 5 (CCR5) are activated through interaction with their ligands and are well known for their role in chemotaxis and signal transduction. While serving these roles, cellular responses are effected, hence the immune function of these molecules is established. Given the role of CCR5 in immune function and that the immune and metabolic systems are interlinked, subsequent immune-directed changes should be measurable at a metabolic level. Numerous investigations have reported on metabolic changes associated with CCR5 status in the presence of disease, so as to understand whether specific CCR5 genotypes, frequency and/or levels offer protection to the host or not. However, these metabolic changes were recorded using older conventional techniques. Depending on certain factors such as the disease model, the geography of the samples and/or the ethnic group under study, the role of CCR5 in disease differs. In addition, little is known about CCR5’s role in the absence of an enhanced inflammatory state, such as when infection persists. Metabolomics is defined as the study of metabolites and informs on metabolic changes within living organisms as induced by various stimuli, such as the interaction of CCR5 with its ligand. Since metabolomics reflects the underlying biochemical activity and state of cells/tissues, this review proposes it as a tool to clarify the contrasting roles of CCR5.

The genome of Ensifer alkalisoli YIC4027 provides insights for host specificity and environmental adaptations

BackgroundEnsifer alkalisoli YIC4027, a recently characterized nitrogen-fixing bacterium of the genus Ensifer, has been isolated from root nodules of the host plant Sesbania cannabina. This plant is widely used as green manure and for soil remediation. E. alkalisoli YIC4027 can grow in saline-alkaline soils and is a narrow-host-range strain that establishes a symbiotic relationship with S. cannabina. The complete genome of this strain was sequenced to better understand the genetic basis of host specificity and adaptation to saline-alkaline soils.ResultsE. alkalisoli YIC4027 was found to possess a 6.1-Mb genome consisting of three circular replicons: one chromosome (3.7 Mb), a chromid (1.9 Mb) and a plasmid (0.46 Mb). Genome comparisons showed that strain YIC4027 is phylogenetically related to broad-host-range Ensifer fredii strains. Synteny analysis revealed a strong collinearity between chromosomes of E. alkalisoli YIC4027 and those of the E. fredii NGR234 (3.9 Mb), HH103 (4.3 Mb) and USDA257 (6.48 Mb) strains. Notable differences were found for genes required for biosynthesis of nodulation factors and protein secretion systems, suggesting a role of these genes in host-specific nodulation. In addition, the genome analysis led to the identification of YIC4027 genes that are presumably related to adaptation to saline-alkaline soils, rhizosphere colonization and nodulation competitiveness. Analysis of chemotaxis cluster genes and nodulation tests with constructed che gene mutants indicated a role of chemotaxis and flagella-mediated motility in the symbiotic association between YIC4027 and S. cannabina.ConclusionsThis study provides a basis for a better understanding of host specific nodulation and of adaptation to a saline-alkaline rhizosphere. This information offers the perspective to prepare optimal E. alkalisoli inocula for agriculture use and soil remediation.

Copine A Interacts with Actin Filaments and Plays a Role in Chemotaxis and Adhesion.

Copines make up a family of calcium-dependent, phospholipid-binding proteins found in numerous eukaryotic organisms. Copine proteins consist of two C2 domains at the N-terminus followed by an A domain similar to the von Willebrand A domain found in integrins. We are studying copine protein function in the model organism, Dictyostelium discoideum, which has six copine genes, cpnA-cpnF. Previous research showed that cells lacking the cpnA gene exhibited a cytokinesis defect, a contractile vacuole defect, and developmental defects. To provide insight into the role of CpnA in these cellular processes, we used column chromatography and immunoprecipitation to isolate proteins that bind to CpnA. These proteins were identified by mass spectrometry. One of the proteins identified was actin. Purified CpnA was shown to bind to actin filaments in a calcium-dependent manner in vitro. cpnA− cells exhibited defects in three actin-based processes: chemotaxis, cell polarity, and adhesion. These results suggest that CpnA plays a role in chemotaxis and adhesion and may do so by interacting with actin filaments.

Calaxin is required for cilia-driven determination of vertebrate laterality

Calaxin is a Ca2+-binding dynein-associated protein that regulates flagellar and ciliary movement. In ascidians, calaxin plays essential roles in chemotaxis of sperm. However, nothing has been known for the function of calaxin in vertebrates. Here we show that the mice with a null mutation in Efcab1, which encodes calaxin, display typical phenotypes of primary ciliary dyskinesia, including hydrocephalus, situs inversus, and abnormal motility of trachea cilia and sperm flagella. Strikingly, both males and females are viable and fertile, indicating that calaxin is not essential for fertilization in mice. The 9 + 2 axonemal structures of epithelial multicilia and sperm flagella are normal, but the formation of 9 + 0 nodal cilia is significantly disrupted. Knockout of calaxin in zebrafish also causes situs inversus due to the irregular ciliary beating of Kupffer’s vesicle cilia, although the 9 + 2 axonemal structure appears to remain normal.

Borrelia burgdorferi chemotaxis toward tick protein Salp12 contributes to acquisition

Lyme disease is a common tick-borne infection caused by the spirochete Borrelia burgdorferi sensu stricto (s.s.). B. burgdorferi s.s. may utilize chemotaxis, the directional migration towards or away from a chemical stimulus, for transmission, acquisition, and infection. However, the specific signals recognized by the spirochete for these events have not been defined. In this study, we identify an Ixodes scapularis salivary gland protein, Salp12, that is a chemoattractant for the spirochete. We demonstrate that Salp12 is expressed in the I. scapularis salivary glands and midgut and expression is not impacted by B. burgdorferi s.s. infection. Knockdown of Salp12 in the salivary glands or passive immunization against Salp12 reduces acquisition of the spirochete by ticks but acquisition is not completely prevented. Knockdown does not impact transmission of B. burgdorferi s.s. This work suggests a new role for chemotaxis in acquisition of the spirochete and suggests that recognition of Salp12 contributes to this phenomenon.

Evidence for a GPR18 Role in Chemotaxis, Proliferation, and the Course of Wound Closure in the Cornea.

We previously showed that cannabinoid-related GPR18 receptors are present in the murine corneal epithelium, but their function remains unknown. The related CB1 receptors regulate corneal healing, possibly via chemotaxis. We therefore examined a potential role for GPR18 in corneal epithelial chemotaxis and wound healing. We examined GPR18 messenger RNA (mRNA) and protein expression in the cornea. We additionally examined GPR18 action in cultured bovine corneal epithelial cells (bCECs) using Boyden and tracking assays, as well as proliferation and signaling. Finally, we examined wound closure in murine corneal explants. GPR18 mRNA was upregulated with injury in the mouse cornea. GPR18 protein was present in basal epithelial cells of the mouse and cow and redistributed to the wound site upon injury. GPR18 ligand N-arachidonoylglycine induced bCEC chemotaxis. The endocannabinoid arachidonoylethanolamine also induced chemotaxis via fatty acid amide hydrolase-mediated metabolism to N-arachidonoylglycine. GPR18 receptor activation additionally induced bCEC proliferation. In an explant model, the GPR18 antagonist O-1918 slowed corneal epithelial cell migration and the rate of corneal wound closure. Corneal GPR18 activation induced both chemotaxis and proliferation in corneal epithelial cells in vitro and impacted wound healing. GPR18 may contribute to the maintenance of corneal integrity.

Transcriptome analysis of hopanoid deficient mutant of Rhodopseuodomonas palustris TIE-1

All three domains of life have an ordered plasma membrane which is pivotal in the selective fitness of primitive life. Like cholesterol in eukaryotes, hopanoids are important in bacteria to modulate membrane order. Hopanoids are pentacyclic triterpenoid lipids biosynthesised in many eubacteria, few ferns and lichens. Hopanoid modulates outer membrane order and hopanoid deficiency results in the weakened structural integrity of the membrane which may in turn affect the other structures within or spanning the cell envelope and contributing to various membrane functions. Hence, to decipher the role of hopanoid, genome-wide transcriptome of wild-type and Δshc mutant of Rhodopseudomonas palustris TIE-1 was studied which indicated 299 genes were upregulated and 306 genes were downregulated in hopanoid deficient mutant, representing ∼11.5% of the genome. Thirty-eight genes involved in chemotaxis, response to stimuli and signal transduction were differentially regulated and impaired motility in hopanoid deficient mutant showed that hopanoid plays a crucial role in chemotaxis. The docking study demonstrated that diguanylate cyclase which catalyses the synthesis of secondary messenger exhibited the capability to interact with hopanoids and might be confederating in chemotaxis and signal transduction. Seventy-four genes involved in membrane transport were differentially expressed and cell assays also explicit that the multidrug transport is compromised in Δshc mutant. Membrane transport is reliant on hopanoids which may explain the basis for previous observations linking hopanoids to antibiotic resistance. Disturbing the membrane order by targeting lipid synthesis can be a possible novel approach in developing new antimicrobials and hopanoid biosynthesis could be a potential target.

The transducer-like protein Tlp12 of Campylobacter jejuni is involved in glutamate and pyruvate chemotaxis

BackgroundCampylobacter jejuni is one of the most common bacterial causes of food-borne enteritis worldwide. Chemotaxis in C. jejuni is known to be critical for the successful colonization of the host and key for the adaptation of the microbial species to different host environments. In C. jejuni, chemotaxis is regulated by a complex interplay of 13 or even more different chemoreceptors, also known as transducer-like proteins (Tlps). Recently, a novel chemoreceptor gene, tlp12, was described and found to be present in 29.5% of the investigated C. jejuni strains.ResultsIn this study, we present a functional analysis of Tlp12 with the aid of a tlp12 knockout mutant of the C. jejuni strain A17. Substrate specificity was investigated by capillary chemotaxis assays and revealed that Tlp12 plays an important role in chemotaxis towards glutamate and pyruvate. Moreover, the Δtlp12 mutant shows increased swarming motility in soft agar assays, an enhanced invasion rate into Caco-2 cells and an increased autoagglutination rate. The growth rate was slightly reduced in the Δtlp12 mutant. The identified phenotypes were in partial restored by complementation with the wild type gene. Tlp12-harboring C. jejuni strains display a strong association with chicken, whose excreta are known to contain high glutamate levels.ConclusionsTLP12 is a chemoreceptor for glutamate and pyruvate recognition. Deletion of tlp12 has an influence on distinct physiological features, such as growth rate, swarming motility, autoagglutination and invasiveness.

Influence of Chemotaxis and Swimming Patterns on the Virulence of the Coral Pathogen Vibrio coralliilyticus.

Chemotaxis, the directed movement toward or away from a chemical signal, can be essential to bacterial pathogens for locating hosts or avoiding hostile environments. The coral pathogen Vibrio coralliilyticus chemotaxes toward coral mucus; however, chemotaxis has not been experimentally demonstrated to be important for virulence. To further examine this, in-frame mutations were constructed in genes predicted to be important for V. coralliilyticus chemotaxis. Most Vibrio genomes contain multiple homologs of various chemotaxis-related genes, and two paralogs of each for cheB, cheR, and cheA were identified. Based on single mutant analyses, the paralogs cheB2, cheR2, and cheA1 were essential for chemotaxis in laboratory assays. As predicted, the ΔcheA1 and ΔcheR2 strains had a smooth-swimming pattern, while the ΔcheB2 strain displayed a zigzag pattern when observed under light microscopy. However, these mutants, unlike the parent strain, were unable to chemotax toward the known attractants coral mucus, dimethylsulfoniopropionate, and N-acetyl-d-glucosamine. The ΔcheB2 strain and an aflagellate ΔfliG1 strain were avirulent to coral, while the ΔcheA1 and ΔcheR2 strains were hypervirulent (90 to 100% infection within 14 h on average) compared to the wild-type strain (66% infection within 36 h on average). Additionally, the ΔcheA1 and ΔcheR2 strains appeared to better colonize coral fragments than the wild-type strain. These results suggest that although chemotaxis may be involved with infection (the ΔcheB2 strain was avirulent), a smooth-swimming phenotype is important for bacterial colonization and infection. This study provides valuable insight into understanding V. coralliilyticus pathogenesis and how this pathogen may be transmitted between hosts.IMPORTANCE Corals are responsible for creating the immense structures that are essential to reef ecosystems; unfortunately, pathogens like the bacterium Vibrio coralliilyticus can cause fatal infections of reef-building coral species. However, compared to related human pathogens, the mechanisms by which V. coralliilyticus initiates infections and locates new coral hosts are poorly understood. This study investigated the effects of chemotaxis, the directional swimming in response to chemical signals, and bacterial swimming patterns on infection of the coral Montipora capitata Infection experiments with different mutant strains suggested that a smooth-swimming pattern resulted in hypervirulence. These results demonstrate that the role of chemotaxis in coral infection may not be as straightforward as previously hypothesized and provide valuable insight into V. coralliilyticus pathogenesis.

Clinicopathological and prognostic significance of preoperative serum epidermal growth factor levels in patients with oral squamous cell carcinoma

Epidermal growth factor (EGF) promotes tumourigenesis and tissue repair of epithelial and mesenchymal cells and has a role in chemotaxis, mitogenesis, cell motility, and cytoprotection. It also enhances the growth of cancers. EGF may therefore have a role in the initiation or promotion of oral carcinogenesis. The cases of 152 patients with oral squamous cell carcinoma whose preoperative serum EGF level was determined by enzyme-linked immunosorbent assay were analyzed retrospectively, along with those of 40 age- and sex-matched controls. Patients with higher levels of EGF were more likely to have neck lymph node metastasis (P=0.026), advanced stage cancer (P=0.04), and a worse survival status (P=0.0019). Multivariate analysis using the Cox proportional hazards model indicated that the EGF level was an independent predictor of poor survival (hazard ratio 1.99, P=0.018). Patients with higher preoperative serum EGF levels had significantly poorer cancer-specific survival by Kaplan–Meier analysis (P=0.032). This study indicates that a higher preoperative serum EGF level is associated with neck lymph node metastasis, more advanced stage, and poor survival. EGF should be considered as a potential prognostic biomarker and a therapeutic target for patients with oral cancer.

The CXC Chemokine Receptor 3 Inhibits Autoimmune Cholangitis via CD8+ T Cells but Promotes Colitis via CD4+ T Cells.

CXC chemokine receptor 3 (CXCR3), a receptor for the C-X-C motif chemokines (CXCL) CXCL9, CXCL10, and CXCL11, which not only plays a role in chemotaxis but also regulates differentiation and development of memory and effector T cell populations. Herein, we explored the function of CXCR3 in the modulation of different organ-specific autoimmune diseases in interleukin (IL)-2 receptor deficiency (CD25−/−) mice, a murine model for both cholangitis and colitis. We observed higher levels of CXCL9 and CXCL10 in the liver and colon and higher expression of CXCR3 on T cells of the CD25−/− mice compared with control animals. Deletion of CXCR3 resulted in enhanced liver inflammation but alleviated colitis. These changes in liver and colon pathology after CXCR3 deletion were associated with increased numbers of hepatic CD4+ and CD8+ T cells, in particular effector memory CD8+ T cells, as well as decreased T cells in mesenteric lymph nodes and colon lamina propria. In addition, increased interferon-γ response and decreased IL-17A response was observed in both liver and colon after CXCR3 deletion. CXCR3 modulated the functions of T cells involved in different autoimmune diseases, whereas the consequence of such modulation was organ-specific regarding to their effects on disease severity. Our findings emphasize the importance of extra caution in immunotherapy for organ-specific autoimmune diseases, as therapeutic interventions aiming at a target such as CXCR3 for certain disease could result in adverse effects in an unrelated organ.