The generation of pathogen-specific immune responses is dependent on the signaling capabilities of pathogen-recognition receptors. DC-SIGN is a C-type lectin that mediates capture and internalization of viral, bacterial, and fungal pathogens by myeloid dendritic cells. DC-SIGN–interacting pathogens are thought to modulate dendritic cell maturation by interfering with intracellular signaling from Toll-like receptor molecules. We report that engagement of DC-SIGN by specific antibodies does not promote dendritic cell maturation but induces ERK1/2 and Akt phosphorylation without concomitant p38MAPK activation. DC-SIGN ligation also triggers PLCγ phosphorylation and transient increases in intracellular calcium in dendritic cells. In agreement with its signaling capabilities, a fraction of DC-SIGN molecules partitions within lipid raft–enriched membrane fractions both in DC-SIGN–transfected and dendritic cells. Moreover, DC-SIGN in dendritic cells coprecipitates with the tyrosine kinases Lyn and Syk. The relevance of the DC-SIGN–initiated signals was demonstrated in monocyte-derived dendritic cells, as DC-SIGN cross-linking synergizes with TNF-α for IL-10 release and enhances the production of LPS-induced IL-10. These results demonstrate that DC-SIGN–triggered intracellular signals modulate dendritic cell maturation. Since pathogens stimulate Th2 responses via preferential activation of ERK1/2, these results provide a molecular explanation for the ability of DC-SIGN–interacting pathogens to preferentially evoke Th2-type immune responses.

SummaryThe CRISPR/Cas9 system and related RNA‐guided endonucleases can introduce double‐strand breaks (DSBs) at specific sites in the genome, allowing the generation of targeted mutations in one or more genes as well as more complex genomic rearrangements. Modifications of the canonical CRISPR/Cas9 system from Streptococcus pyogenes and the introduction of related systems from other bacteria have increased the diversity of genomic sites that can be targeted, providing greater control over the resolution of DSBs, the targeting efficiency (frequency of on‐target mutations), the targeting accuracy (likelihood of off‐target mutations) and the type of mutations that are induced. Although much is now known about the principles of CRISPR/Cas9 genome editing, the likelihood of different outcomes is species‐dependent and there have been few comparative studies looking at the basis of such diversity. Here we critically analyse the activity of CRISPR/Cas9 and related systems in different plant species and compare the outcomes in animals and microbes to draw broad conclusions about the design principles required for effective genome editing in different organisms. These principles will be important for the commercial development of crops, farm animals, animal disease models and novel microbial strains using CRISPR/Cas9 and other genome‐editing tools.

IntroductionThe identification of the lectin gene cluster at chromosome 19p13.2 1 has led to the realization that some C-type lectins are capable of mediating intercellular adhesion, pathogen-binding, and antigen internalization for induction of T cell responses. 2 The paradigmatic example of this type of lectin is dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), which efficiently internalizes antigens, 3 mediates dendritic cell intercellular adhesions, 4 and recognizes a wide range of microorganisms through binding to mannose-and Lewis-containing glycans. 5 C-type lectins on dendritic cells enhance their ability for pathogen recognition 6 and contribute to modulation of toll-like receptor (TLR)-initiated signals. 7 Consequently, the definition of the range of dendritic cell lectins and their binding specificities might provide adequate targets for immune intervention and prevention of pathogen entrance and spreading.The lectin gene cluster at chromosome 19p13.2 includes the genes encoding for the type II C-type lectins DC-SIGN, liver/lymph node-specific intercellular adhesion molecule-3-grabbing integrin (L-SIGN), CD23, and liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin). 1,4,8,9 DC-SIGN is expressed on myeloid dendritic cells, 4,10 and alternatively activated in vitro on macrophages. 11 In vivo it is found on interstitial dendritic cells, 12 a subset of CD14ϩ peripheral blood DC, 13 human microvascular endothelial cells, 8 and on synovial, placenta, lymph node, and alveolar macrophages. 14-16 By contrast, L-SIGN is exclusively expressed on endothelial cells of the liver, lymph nodes, and placenta, 17,18 but not on myeloid cells.The LSECtin (CLEC4G) gene is located between the CD23 and DC-SIGN genes with the three genes arranged in the same orientation. 9 LSECtin encodes a protein with a lectin domain followed by a 110-residue stalk region, a transmembrane domain, and a 31-residue cytoplasmic domain. 9 LSECtin has been previously detected on liver and lymph node sinusoidal endothelial cells at the protein and RNA level. 9 LSECtin functions as an attachment factor for Ebola virus and SARS, but it does not bind HIV or hepatitis C virus. 19 We now describe the expression of LSECtin isoforms in ex vivo isolated human peripheral blood and thymic dendritic cells as well as in dendritic cells and macrophages generated in vitro. LSECtin exhibits ligand-induced internalization, and its sugar recognition specificity differs from that of DC-SIGN. The presence of LSECtin on myeloid cells should therefore contribute to expanding their antigen-capture and pathogen-recognition capabilities. Materials and methodsThe study described was approved by the Centro de Investigaciones Biologicas (CSIC) Institutional Review Board. The study did not involve any direct contact with human subjects. Cell cultureHuman peripheral blood mononuclear cells were isolated from buffy coats from normal donors over a Lymphoprep (Nycomed Pharma, Oslo, Norway) gradient according to sta...

The expression of the new Ly108 isoform H1 weakens lupus-like disease of C57BL/6.Sle1b mice.

Selectable marker gene systems are vital for the development of transgenic crops. Since the creation of the first transgenic plants in the early 1980s and their subsequent commercialization worldwide over almost an entire decade, antibiotic and herbicide resistance selectable marker gene systems have been an integral feature of plant genetic modification. Without them, creating transgenic crops is not feasible on purely economic and practical terms. These systems allow the relatively straightforward identification and selection of plants that have stably incorporated not only the marker genes but also genes of interest, for example herbicide tolerance and pest resistance. Bacterial antibiotic resistance genes are also crucial in molecular biology manipulations in the laboratory. An unprecedented debate has accompanied the development and commercialization of transgenic crops. Divergent policies and their implementation in the European Union on one hand and the rest of the world on the other (industrialized and developing countries alike), have resulted in disputes with serious consequences on agricultural policy, world trade and food security. A lot of research effort has been directed towards the development of markerfree transformation or systems to remove selectable markers. Such research has been in a large part motivated by perceived problems with antibiotic resistance selectable markers; however, it is not justified from a safety point of view. The aim of this review is to discuss in some detail the currently available scientific evidence that overwhelmingly argues for the safety of these marker gene systems. Our conclusion, supported by numerous studies, most of which are commissioned by some of the very parties that have taken a position against the use of antibiotic selectable marker gene systems, is that there is no scientific basis to argue against the use and presence of selectable marker genes as a class in transgenic plants.