The BCR signals through conserved immunoreceptor tyrosinebased activation motifs (ITAMs) found within the cytoplasmic tails of its subunits. Ligation by antigen results in the activation of associated cytoplasmic protein tyrosine kinases (PTKs), including Syk, the Src-family PTKs Lyn and Fyn, and Btk. 2,3 The activated Lyn and Fyn kinases phosphorylate the ITAMs within the immunoglobulin alpha (Ig-␣) and Ig-␤ chains, resulting in the recruitment and activation of Syk. As a result, molecular scaffolds composed of adaptor proteins and key enzymes, such as phospholipase C ␥ (PLC-␥), phosphatidylinositol 3-kinase (PI3K), and guanine nucleotide exchange factors (GEFs) Vav1 and Vav2, are assembled and activated at the plasma membrane by Src and/or Syk PTKs. These scaffolds transduce signals to the cytoplasm and nucleus to activate gene expression and metabolic changes involved in B-cell homeostasis.One critical pathway stimulated by BCR triggers intracytoplasmic calcium movements leading to the activation of transcription factors, such as nuclear factor of activated T cells (NFATs). These nuclear factors coordinate the expression of cytokines and cellcycle proteins involved in B-cell growth and apoptosis. Calcium signals are triggered by activated PLC-␥ that produces inositol-1,4,5-triphosphate (IP3), followed by an increase of cytoplasmic calcium. 4 The regulation of PLC-␥ activity involves the membrane translocation and activation of Btk following PI3K-mediated production of phosphatidylinositol-3,4,5-triphosphate (PIP3). 5,6 Vav proteins also participate to the regulation of calcium signals and NFAT activation in lymphocytes. Vav proteins are activators of Rho family GTPases that control cytoskeletal reorganization and gene activation. 7,8 Analysis of Vav1-and Vav2-deficient mice showed the importance of these proteins in BCR signaling during development, maturation, and proliferation of B cells. [9][10][11] The major defect in vav1 Ϫ/Ϫ ϫ vav2 Ϫ/Ϫ B cells stimulated through antigen receptor appears to be a defect in calcium release. Although the basis for this defect is still unclear, it likely involves defects in PI3K, PLC-␥, and Tec-family kinases activation, since this phenomenon has been observed in Vav1-deficient T and mast cells. 12,13 Moreover, Vav3 has been shown to regulate PI3K activation in the DT40 chicken B-cell line. 14 The assembly of signaling complexes is regulated by adaptor proteins that mediate protein-protein or protein-lipid interactions. 15 In B cells, one such adaptor is the Syk substrate BLNK/SLP-65, which connects BCR to PLC-␥ activation by prodiving docking sites for Btk and PLC-␥2. 16,17 In a screen for Syk-kinase interacting proteins, we previously identified 3BP2, 18 a cytoplasmic adaptor originally identified as an Abl Src homology domain 3 (SH3) binding protein. 19 3BP2 (also known as SH3BP2) is preferentially expressed in hematopoietic tissues, 18,20 and positively regulates the activity of the transcription factors NFAT and AP-1 in T cells through calcineurin and Ras-dependent path...

Inflammation induced by Helicobacter pylori infection related to gastric carcinogenesis. In this study, we have investigated the anti-inflammatory effect and its mechanism of kaempferol in the inflammatory response caused by H. pylori infection in vitro. We found that kaempferol reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-8) and production of IL-8 in AGS cells. In addition, kaempferol suppressed translocation of cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) of H. pylori to AGS cells. It was due to decreased transcription of type IV secretion system (T4SS) components involved in CagA injection and secretion system subunit protein A (SecA) of type V secretion system (T5SS) involved in VacA secretion by kaempferol. In conclusion, kaempferol shows the anti-inflammatory effect by suppressing the translocation of CagA and VacA proteins and leading to the down-regulation of pro-inflammatory cytokines. Abbreviations: CagA: cytotoxin-associated gene A; VacA: vacuolating cytotoxin A; T4SS: type IV secretion systems; SecA: secretion system subunit protein A; T5SS: type V secretion system;

This D. melanogaster-M. abscessus infection/curing methodology may be useful for the rapid evaluation of potential drug candidates. In addition, new combinations using tigecycline and linezolid should be considered as possible next-generation combination therapies to be assessed in higher organisms.

Two key virulence factors of Helicobacter pylori are the secreted virulent proteins of vacuolating toxin A (VacA) and cytotoxin associated protein A (CagA) which lead to damages of gastric epithelial cells. We previously identified that the cyanidin 3-O-glucoside (C3G) inhibits the secretion of both VacA and CagA. In the current report, we show that C3G inhibits VacA secretion in a dose-dependent manner by inhibiting secretion system subunit protein A (SecA) synthesis. As SecA is involved in translocation of bacterial proteins, we predicted that inhibition of the SecA pathway by C3G should decrease H. pylori-induced cell death. To test this hypothesis, the human gastric cell line KATO III cells were co-cultured with H. pylori 60190 (VacA+/CagA+) and C3G. We found that C3G treatment caused a decrease in activation of the pro-apoptotic proteins caspase-3/-8 in H. pylori-infected cells leading to a decrease in cell death. Our data suggest that consumption of foods containing anthocyanin may be beneficial in reducing cell damage due to H. pylori infection.

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Extracts of Thladiantha grosvenorii fruits, Stevia rebaudiana leaves, and Abrus precatorius leaves were investigated using Mongolian gerbil electrophysiological and conditioned taste aversion procedures, which were designed to respond to sucrose. A close correlation was observed between extracts of these sweet plants known to contain sweet principles and those extracts indicated as being sweet by a combination of these gerbil bioassays. The methods employed seem to be suitable for use in aiding the purification of highly sweet compounds of plant origin.

The adapter 3BP2 is involved in leukocyte signaling downstream Src/Syk-kinases coupled immunoreceptors. Here, we show that 3BP2 directly interacts with the endocytic scaffold protein CIN85 and the actin-binding protein HIP-55. 3BP2 colocalized with CIN85 and HIP-55 in T cell rafts and at the T cell/APC synapse, an active zone of receptors and proteins recycling. A binding region of CIN85 SH3 domains on 3BP2 was mapped to a PVPTPR motif in the first proline-rich region of 3BP2, whereas the C-terminal SH3 domain of HIP-55 bound a more distal proline-rich domain of 3BP2. Together, our data suggest an unexpected role of 3BP2 in endocytic and cytoskeletal regulation through its interaction with CIN85 and HIP-55.

Mycobacterium abscessus is a rapidly growing life-threatening mycobacterium with multiple drug-resistance mechanisms. However, there is no official regimen for M. abscessus therapy. In this study, we screened the Pathogen Box, which contains 400 drug-like molecules active against neglected diseases, to identify active molecules targeting Mycobacterium abscessus using resazurin live/dead assays. In this screening assay, the Z-factor was 0.7, as an indicator of the statistical confidence of the assay. A cut-off of 80% growth inhibition in the screening resulted in the identification of four different compounds at a single concentration (20 μM). Dose-response curves identified three different hit candidates, i.e., MMV688508, MMV688844, and MMV688845, which generated good inhibitory curves. All hit candidates were expected to have different molecular targets. Among them, MMV688844 showed the best minimum inhibitory concentration value for not only wild-type M. abscessus but also for nine different R and S morphotype clinical isolates. Thus, we found that MMV688844, identified from the Pathogen Box screen, may be a promising candidate in the M. abscessus drug discovery pipeline.