Mechanism and function of Vav1 localisation in TCR signalling

The antigen-specific binding of T cells to antigen presenting cells results in recruitment of signalling proteins to microclusters at the cell-cell interface known as the immunological synapse (IS). The Vav1 guanine nucleotide exchange factor plays a critical role in T cell antigen receptor (TCR) signalling, leading to the activation of multiple pathways. We now show that it is recruited to microclusters and to the IS in primary CD4+ and CD8+ T cells. Furthermore, we show that this recruitment depends on the SH2 and C-terminal SH3 (SH3B) domains of Vav1, and on phosphotyrosines 112 and 128 of the SLP76 adaptor protein. Biophysical measurements show that Vav1 binds directly to these residues on SLP76 and that efficient binding depends on the SH2 and SH3B domains of Vav1. Finally, we show that the same two domains are critical for the phosphorylation of Vav1 and its signalling function in TCR-induced calcium flux. We propose that Vav1 is recruited to the IS by binding to SLP76 and that this interaction is critical for the transduction of signals leading to calcium flux

Efficient ligand discovery using sulfur(VI) fluoride reactive fragments

Sulfur(VI) fluorides (SFs) have emerged as valuable electrophiles for the design of "beyond-cysteine" covalent inhibitors and offer potential for expansion of the liganded proteome. Since SFs target a broad range of nucleophilic amino acids, they deliver an approach for the covalent modification of proteins without requirement for a proximal cysteine residue. Further to this, libraries of reactive fragments present an innovative approach for the discovery of ligands and tools for proteins of interest by leveraging a breadth of mass spectrometry analytical approaches. Herein, we report a screening approach that exploits the unique properties of SFs for this purpose. Libraries of SF-containing reactive fragments were synthesized, and a direct-to-biology workflow was taken to efficiently identify hit compounds for CAII and BCL6. The most promising hits were further characterized to establish the site(s) of covalent modification, modification kinetics, and target engagement in cells. Crystallography was used to gain a detailed molecular understanding of how these reactive fragments bind to their target. It is anticipated that this screening protocol can be used for the accelerated discovery of "beyond-cysteine" covalent inhibitors

The Tandem CARDs of NOD2: Intramolecular Interactions and Recognition of RIP2

Caspase recruitment domains (CARDs) are homotypic protein interaction modules that link the stimulus-dependent assembly of large signaling platforms such as inflammasomes to the activation of downstream effectors that often include caspases and kinases and thereby play an important role in the regulation of inflammatory and apoptotic signaling pathways. NOD2 belongs to the NOD-like (NLR) family of intracellular pattern recognition receptors (PRR) and induces activation of the NF-κB pathway in response to the recognition of bacterial components. This process requires the specific recognition of the CARD of the protein kinase RIP2 by the tandem CARDs of NOD2. Here we demonstrate that the tandem CARDs of NOD2 are engaged in an intramolecular interaction that is important for the structural stability of this region. Using a combination of ITC and pull-down experiments we identify distinct surface areas that are involved in the intramolecular tandem CARD interaction and the interaction with the downstream effector RIP2. Our findings indicate that while CARDa of NOD2 might be the primary binding partner of RIP2 the two CARDs of NOD2 do not act independently of one another but may cooperate to from a binding surface that is distinct from that of single CARDs

The Origin of Intraspecific Variation of Virulence in an Eukaryotic Immune Suppressive Parasite

Occurrence of intraspecific variation in parasite virulence, a prerequisite for coevolution of hosts and parasites, has largely been reported. However, surprisingly little is known of the molecular bases of this variation in eukaryotic parasites, with the exception of the antigenic variation used by immune-evading parasites of mammals. The present work aims to address this question in immune suppressive eukaryotic parasites. In Leptopilina boulardi, a parasitic wasp of Drosophila melanogaster, well-defined virulent and avirulent strains have been characterized. The success of virulent females is due to a major immune suppressive factor, LbGAP, a RacGAP protein present in the venom and injected into the host at oviposition. Here, we show that an homologous protein, named LbGAPy, is present in the venom of the avirulent strain. We then question whether the difference in virulence between strains originates from qualitative or quantitative differences in LbGAP and LbGAPy proteins. Results show that the recombinant LbGAPy protein has an in vitro GAP activity equivalent to that of recombinant LbGAP and similarly targets Drosophila Rac1 and Rac2 GTPases. In contrast, a much higher level of both mRNA and protein is found in venom-producing tissues of virulent parasitoids. The F1 offspring between virulent and avirulent strains show an intermediate level of LbGAP in their venom but a full success of parasitism. Interestingly, they express almost exclusively the virulent LbGAP allele in venom-producing tissues. Altogether, our results demonstrate that the major virulence factor in the wasp L. boulardi differs only quantitatively between virulent and avirulent strains, and suggest the existence of a threshold effect of this molecule on parasitoid virulence. We propose that regulation of gene expression might be a major mechanism at the origin of intraspecific variation of virulence in immune suppressive eukaryotic parasites. Understanding this variation would improve our knowledge of the mechanisms of transcriptional evolution currently under active investigation

Monosomy 1p36 - a recently delineated, clinically recognizable syndrome.

Monosomy 1p36 ^ a recently delineated, clinically recognizable syndrome M. Zenker a ,O.Rittinger b ,K.-P.Grosse c , M.R. Speicher d ,J.Kraus d ,A.Rauch a and U.Trautmann a a Institut fˇr Humangenetik der Universitt Erlangen-Nˇrnberg, Germany; b Klinische Genetik, Kinderspital, Landeskrankenanstalten Salzburg, Austria; c KinderarztpraxisPDDr.med.Dr.med.habil.Grosse,H ̨chstadt/Aisch,Germany; d Institut fˇr Anthropologie und Humangenetik, Ludwig-Maximilian-Universitt Mˇnchen, Germany Correspondence to (present address) Dr med. Martin Zenker, Universitts-Klinik fˇr Kinder und Jugendliche, Loschgestrasse 15, 91054 Erlangen, Germany Tel.:+4991318533118;Fax:+4991318533113; E-mail: martin.zenker @ kinder.imed.uni-erlangen.de Received:9March2001;accepted:26August2001 Monosomy 1p36 is a recently delineated contiguous gene syndrome, which is now considered to be one of the most common subtelomeric microdeletion syndromes. We report four unrelated patients with subtle deletions within 1p36 confirmed by high resolution karyotyping and FISH. All exhibited severe psychomotor retardation. Microcephaly, seizures, and visual impairment occurred in three subjects. Results of a first routine karyotyping were unrevealing in three probands. The diagnosis was primarily suggested on the basis of a distinct pattern of facial anomalies in all except the first case. This report illustrates that monosomy 1p36 may be recognized clinically, at least in some patients, whereas the diagnosis is easily missed on routine karyotype

Removal of sugar sweetened beverages from sale in a hospital setting—Consumer opinion and influence on purchasing behavior

Issue addressed: This study investigated the impact of removing sugar sweetened beverages (SSBs) from sale in a regional health service. Drink purchasing patterns were measured by product ordering data. Consumer opinion regarding the intervention, self-reported packaged drink purchase and consumption were also explored. Methods: Packaged drinks were classified into two categories, SSB or non-SSB and drink types. Drink sales were determined by the collection of product ordering data for all packaged drink types sold, six months prior to and twelve months after the removal of SSBs. A consumer survey was undertaken six months after SSB removal to assess consumer opinion regarding SSB removal, self-reported SSB consumption and purchase. Descriptive and Wilcoxon rank-sum tests analyses assessed differences in packaged drinks purchase, self-reported SSB consumption and purchase. Open-ended survey responses were thematically analysed. Results: The median monthly number of juices, and diet drinks ordered increased significantly (P = .05). 59% of the survey respondents regularly consumed SSBs and 58% agreed or strongly agreed with removing SSBs from sale. However, some consumers felt it was a removal of their freedom of choice. Conclusions: Removing SSBs from sale can result in consumers making healthier purchases. There was support for the initiative as it is seen as the responsibility of the health service to role model healthy eating behaviours. So what? This study indicates removal of SSBs from sale is a promising health promotion intervention that can contribute to positive behaviour change, and potentially influence longer-term health and wellbeing

GJB2 mutations in keratitis-ichthyosis-deafness syndrome including its fatal form

Keratitis-ichthyosis-deafness syndrome (KID; MIM 148210) is a rare congenital disorder characterized by vascularizing keratitis, sensorineural hearing loss (HL), and progressive erythrokeratoderma. Clinical variability including a fatal course of KID in the first year of life has been reported. Germline missense mutations in GJB2, encoding connexin-26, were recently found to cause KID in 14 unrelated juvenile and adult patients. We identified a de novo GJB2 mutation G45E in a patient displaying the fatal form of the disease. No mutations were detected in five other connexin and mitochondrial genes. The G45E mutation was not reported previously in Caucasian patients but was the third most common GJB2 mutation (16% of disease alleles) in Japanese patients with autosomal recessive non-syndromic HL. This finding suggests different modes of action of the same GJB2 mutation depending on the genetic background. This hypothesis was further substantiated by our observation of a variable clinical course in unrelated KID patients from Austria harboring the common D50N mutation in GJB2