Proteomic analysis in primary T cells reveals IL-7 alters T cell receptor thresholding via CYTIP/cytohesin/LFA-1 localisation and activation.

The ability of the cellular immune system to discriminate self from foreign antigens depends on the appropriate calibration of the T-cell receptor (TCR) signalling threshold. The lymphocyte homeostatic cytokine interleukin 7 (IL-7) is known to affect TCR thresholding, but the molecular mechanism is not fully elucidated. A better understanding of this process is highly relevant in the context of autoimmune disease therapy and cancer immunotherapy. We sought to characterise the early signalling events attributable to IL-7 priming; in particular, the altered phosphorylation of signal transduction proteins and their molecular localisation to the TCR. By integrating high-resolution proximity- phospho-proteomic and imaging approaches using primary T cells, rather than engineered cell lines or an in vitro expanded T cell population, we uncovered transduction events previously not linked to IL-7. We show that IL-7 leads to dephosphorylation of cytohesin interacting protein (CYTIP) at a hitherto undescribed phosphorylation site (pThr280) and alters the co-localisation of cytohesin 1 with the TCR and LFA-1 integrin. These results show that IL-7, acting via CYTIP and cytohesin-1, may impact TCR activation thresholds by enhancing the co-clustering of TCR and LFA-1 integrin.

Effects of fatty acid nitroalkanes on signal transduction pathways and airway macrophage activation

Fatty acid nitroalkenes are reversibly-reactive electrophiles that are endogenously detectable at nM concentrations and display anti-inflammatory, pro-survival actions. These actions are elicited through the alteration of signal transduction proteins via a Michael addition on nucleophilic cysteine thiols. Nitrated fatty acids (NO2-FAs), like 9- or 10-nitro-octadec-9-enolic acid, will act on signal transduction proteins directly or on key regulatory proteins to cause an up-regulation or down-regulation of the protein’s expression, yielding an anti-inflammatory response. These responses have been characterized in many organ systems, such as the cardiovascular system, with the pulmonary system less well defined. Macrophages are one of the most abundant immune cells in the lung and are essential in maintaining lung homeostasis. Despite this, macrophages can play a role in both acute and chronic lung injury due to up-regulation of anti-inflammatory signal transduction pathways and down-regulation of pro-inflammatory pathways. Through their propensity to alter signal transduction pathways, NO2-FAs may be able to reduce macrophage activation during pulmonary injury. This review will focus on the implications of NO2-FAs on macrophage activation in the lung and the signal transduction pathways that may be altered, leading to reduced pulmonary injury.

Distinct Roles of Vav Family Members in Adaptive and Innate Immune Models of Arthritis

Genetic evidence suggests that three members of the VAV family (VAV1, VAV2 and VAV3) of signal transduction proteins could play important roles in rheumatoid arthritis. However, it is not known currently whether the inhibition of these proteins protects against this disease and, if so, the number of family members that must be eliminated to get a therapeutic impact. To address this issue, we have used a collection of single and compound Vav family knockout mice in experimental models for antigen-dependent (methylated bovine serum albumin injections) and neutrophil-dependent (Zymosan A injections) rheumatoid arthritis in mice. We show here that the specific elimination of Vav1 is sufficient to block the development of antigen-induced arthritis. This protection is likely associated with the roles of this Vav family member in the development and selection of immature T cells within the thymus as well as in the subsequent proliferation and differentiation of effector T cells. By contrast, we have found that depletion of Vav2 reduces the number of neutrophils present in the joints of Zymosan A-treated mice. Despite this, the elimination of Vav2 does not protect against the joint degeneration triggered by this experimental model. These findings indicate that Vav1 is the most important pharmacological target within this family, although its main role is limited to the protection against antigen-induced rheumatoid arthritis. They also indicate that the three Vav family proteins do not play redundant roles in these pathobiological processes.

The molecular mechanisms of multidrug resistance of human glioblastomas

In review discusses the phenomenon of drug resistance of GB in the context of the expression of ABC family transporter proteins and the processes of proliferation, angiogenesis, recurrence and death. The emphasis is on the identifying for molecular targets among growth factors, receptors, signal transduction proteins, microRNAs, transcription factors, proto-oncogenes, tumor suppressor genes and their polymorphic variants (SNPs) for the development and creation of targeted anticancer drugs.

Divergence in Coding Sequence and Expression of Different Functional Categories of Immune Genes between Two Wild Rodent Species

Differences in immune function between species could be a result of interspecific divergence in coding sequence and/or expression of immune genes. Here, we investigate how the degree of divergence in coding sequence and expression differs between functional categories of immune genes, and if differences between categories occur independently of other factors (expression level, pleiotropy). To this end, we compared spleen transcriptomes of wild-caught yellow-necked mice and bank voles. Immune genes expressed in the spleen were divided into four categories depending on the function of the encoded protein: pattern recognition receptors (PRR); signal transduction proteins; transcription factors; and cyto- and chemokines and their receptors. Genes encoding PRR and cyto-/chemokines had higher sequence divergence than genes encoding signal transduction proteins and transcription factors, even when controlling for potentially confounding factors. Genes encoding PRR also had higher expression divergence than genes encoding signal transduction proteins and transcription factors. There was a positive correlation between expression divergence and coding sequence divergence, in particular for PRR genes. We propose that this is a result of that divergence in PRR coding sequence leads to divergence in PRR expression through positive feedback of PRR ligand binding on PRR expression. When controlling for sequence divergence, expression divergence of PRR genes did not differ from other categories. Taken together, the results indicate that coding sequence divergence of PRR genes is a major cause of differences in immune function between species.

The Campylobacter jejuni chemoreceptor Tlp10 has a bimodal ligand-binding domain and specificity for multiple classes of chemoeffectors

Campylobacter jejuni is a bacterial pathogen that is a common cause of enteritis in humans. We identified a previously uncharacterized type of sensory domain in the periplasmic region of the C. jejuni chemoreceptor Tlp10, termed the DAHL domain, that is predicted to have a bimodular helical architecture. Through two independent ligand-binding sites in this domain, Tlp10 responded to molecular aspartate, isoleucine, fumarate, malate, fucose, and mannose as attractants and to arginine, galactose, and thiamine as repellents. Tlp10 also recognized glycan ligands when present as terminal and intermediate residues of complex structures, such as the fucosylated human ganglioside GM1 and Lewisa antigen. A tlp10 mutant strain lacking the ligand-binding sites was attenuated in its ability to colonize avian caeca and to adhere to cultured human intestinal cells, indicating the potential involvement of the DAHL domain in host colonization and disease. The Tlp10 intracellular signaling domain interacted with the scaffolding proteins CheV and CheW, which couple chemoreceptors to intracellular signaling machinery, and with the signaling domains of other chemoreceptors, suggesting a key role for Tlp10 in signal transduction and incorporation into sensory arrays. We identified the DAHL domain in other bacterial signal transduction proteins, including the essential virulence induction protein VirA from the plant pathogen Agrobacterium tumefaciens. Together, these results suggest a potential link between Tlp10 and C. jejuni virulence.

Identification of signaling pathways, matrix-digestion enzymes, and motility components controllingVibrio choleraebiofilm dispersal

Bacteria alternate between being free-swimming and existing as members of sessile multicellular communities called biofilms. The biofilm lifecycle occurs in three stages: cell attachment, biofilm maturation, and biofilm dispersal.Vibrio choleraebiofilms are hyperinfectious, and biofilm formation and dispersal are considered central to disease transmission. While biofilm formation is well studied, almost nothing is known about biofilm dispersal. Here, we conducted an imaging screen forV. choleraemutants that fail to disperse, revealing three classes of dispersal components: signal transduction proteins, matrix-degradation enzymes, and motility factors. Signaling proteins dominated the screen and among them, we focused on an uncharacterized two-component sensory system that we term DbfS/DbfR for dispersal of biofilm sensor/regulator. Phospho-DbfR represses biofilm dispersal. DbfS dephosphorylates and thereby inactivates DbfR, which permits dispersal. Matrix degradation requires two enzymes: LapG, which cleaves adhesins, and RbmB, which digests matrix polysaccharides. Reorientation in swimming direction, mediated by CheY3, is necessary for cells to escape from the porous biofilm matrix. We suggest that these components act sequentially: signaling launches dispersal by terminating matrix production and triggering matrix digestion, and subsequent cell motility permits escape from biofilms. This study lays the groundwork for interventions aimed at modulatingV. choleraebiofilm dispersal to ameliorate disease.

Beauvericin Inhibits the Growth of U251 Glioma Cells and Promotes Apoptosis In Vitro

To elucidated the inhibitory effect of beauvericin (BEA) on glioma cells and its possible molecular mechanism, in this study, the MTT assay was performed to observed the effect of BEA on cell proliferation, the flow cytometry was used to measure its protective effect on cell apoptosis, and the Western Blot assay was performed to test the expression levels of signal transduction proteins. In the results, the concentration of BEA was 0.5 μmoL/L in the drug group, indicating that it has obvious protect effect to the U251 cells. The apoptosis rates of BEA, Cis and BEA+Cis groups, compared with the U251 group, were 2.93, 3.71 and 5.0 times higher respectively. In addition, the expression levels of Cyclin D1, E, B and Bcl-2 in BEA group were 75, 69, 78 and 67% of that in the U251 group, while Bax and cleaved caspase-3 were twice as much as that in the U251 group. In conclusion, beauvericin can inhibit U251 cell apoptosis and the possible mechanism is to reduce the expression of Cyclin D1, B, E and Bcl-2, while the levels of Bax and cleaved Caspase-3 increased. Thus, BEA has a broad application prospect in the treatment of glioma.

Identification and analysis of the signaling pathways, matrix-digestion enzymes, and motility components controlling Vibrio cholerae biofilm dispersal

Bacteria alternate between being free-swimming and existing as members of sessile multicellular communities called biofilms. The biofilm lifecycle occurs in three stages: cell attachment, biofilm maturation, and biofilm dispersal. Vibrio cholerae biofilms are hyper-infectious and biofilm formation and dispersal are considered central to disease transmission. While biofilm formation is well-studied, almost nothing is known about biofilm dispersal. Here, we conduct an imaging screen for V. cholerae mutants that fail to disperse, revealing three classes of dispersal components: signal transduction proteins, matrix-degradation enzymes, and motility factors. Signaling proteins dominated the screen and among them, we focused on an uncharacterized two-component sensory system that we name DbfS/DbfR for Dispersal of Biofilm Sensor/Regulator. Phospho-DbfR represses biofilm dispersal. DbfS dephosphorylates and thereby inactivates DbfR, which permits dispersal. Matrix degradation requires two enzymes: LapG, which cleaves adhesins, and RbmB, which digests matrix polysaccharide. Reorientations in swimming direction, mediated by CheY3, are necessary for cells to escape from the porous biofilm matrix. We suggest that these components act sequentially: signaling launches dispersal by terminating matrix production and triggering matrix digestion and, subsequently, cell motility permits escape from biofilms. This study lays the groundwork for interventions that modulate V. cholerae biofilm dispersal to ameliorate disease.

Post-translational modifications and stress adaptation: the paradigm of FKBP51

Adaptation to stress is a fundamental requirement to cope with changing environmental conditions that pose a threat to the homeostasis of cells and organisms. Post-translational modifications (PTMs) of proteins represent a possibility to quickly produce proteins with new features demanding relatively little cellular resources. FK506 binding protein (FKBP) 51 is a pivotal stress protein that is involved in the regulation of several executers of PTMs. This mini-review discusses the role of FKBP51 in the function of proteins responsible for setting the phosphorylation, ubiquitination and lipidation of other proteins. Examples include the kinases Akt1, CDK5 and GSK3β, the phosphatases calcineurin, PP2A and PHLPP, and the ubiquitin E3-ligase SKP2. The impact of FKBP51 on PTMs of signal transduction proteins significantly extends the functional versatility of this protein. As a stress-induced protein, FKBP51 uses re-setting of PTMs to relay the effect of stress on various signaling pathways.