Absence of a paternally inherited FOXP2 gene in developmental verbal dyspraxia

Mutations in FOXP2 cause developmental verbal dyspraxia (DVD), but only a few cases have been described. We characterize 13 patients with DVD--5 with hemizygous paternal deletions spanning the FOXP2 gene, 1 with a translocation interrupting FOXP2, and the remaining 7 with maternal uniparental disomy of chromosome 7 (UPD7), who were also given a diagnosis of Silver-Russell Syndrome (SRS). Of these individuals with DVD, all 12 for whom parental DNA was available showed absence of a paternal copy of FOXP2. Five other individuals with deletions of paternally inherited FOXP2 but with incomplete clinical information or phenotypes too complex to properly assess are also described. Four of the patients with DVD also meet criteria for autism spectrum disorder. Individuals with paternal UPD7 or with partial maternal UPD7 or deletion starting downstream of FOXP2 do not have DVD. Using quantitative real-time polymerase chain reaction, we show the maternally inherited FOXP2 to be comparatively underexpressed. Our results indicate that absence of paternal FOXP2 is the cause of DVD in patients with SRS with maternal UPD7. The data also point to a role for differential parent-of-origin expression of FOXP2 in human speech development.     

The bacterial nucleoid: a highly organized and dynamic structure

Recent advances in bacterial cell biology have revealed unanticipated structural and functional complexity, reminiscent of eukaryotic cells. Particular progress has been made in understanding the structure, replication, and segregation of the bacterial chromosome. It emerged that multiple mechanisms cooperate to establish a dynamic assembly of supercoiled domains, which are stacked in consecutive order to adopt a defined higher-level organization. The position of genetic loci on the chromosome is thereby linearly correlated with their position in the cell. SMC complexes and histone-like proteins continuously remodel the nucleoid to reconcile chromatin compaction with DNA replication and gene regulation. Moreover, active transport processes ensure the efficient segregation of sister chromosomes and the faithful restoration of nucleoid organization while DNA replication and condensation are in progress.     

Heterogeneity in Neutrophil Microparticles Reveals Distinct Proteome and Functional Properties

Altered plasma neutrophil microparticle levels have recently been implicated in a number of vascular and inflammatory diseases, yet our understanding of their actions is very limited. Herein, we investigate the proteome of neutrophil microparticles in order to shed light on their biological actions. Stimulation of human neutrophils, either in suspension or adherent to an endothelial monolayer, led to the production of microparticles containing >400 distinct proteins with only 223 being shared by the two subsets. For instance, postadherent microparticles were enriched in alpha-2 macroglobulin and ceruloplasmin, whereas microparticles produced by neutrophils in suspension were abundant in heat shock 70 kDa protein 1. Annexin A1 and lactotransferrin were expressed in both microparticle subsets. We next determined relative abundance of these proteins in three types of human microparticle samples: healthy volunteer plasma, plasma of septic patients and skin blister exudates finding that these proteins were differentially expressed on neutrophil microparticles from these samples reflecting in part the expression profiles we found in vitro. Functional assessment of the neutrophil microparticles subsets demonstrated that in response to direct stimulation neutrophil microparticles produced reactive oxygen species and leukotriene B₄ as well as locomoted toward a chemotactic gradient. Finally, we investigated the actions of the two neutrophil microparticles subsets described herein on target cell responses. Microarray analysis with human primary endothelial cells incubated with either microparticle subset revealed a discrete modulation of endothelial cell gene expression profile. These findings demonstrate that neutrophil microparticles are heterogenous and can deliver packaged information propagating the activation status of the parent cell, potentially exerting novel and fundamental roles both under homeostatic and disease conditions.The emerging notion that cells can communicate by packaged information represents a major shift in our understanding of cell-to-cell interaction in complex settings including inflammation (1). Packaging of mediators (irrespective of their chemical nature) in structures that can be transported through the vascular and lymphatic systems might avoid their rapid dilution and removal by biological fluids and allow the target cell or tissue to receive a biologically relevant amount of a given molecule. As an example, TNF-α produced by mast cells in the mouse paw can reach the lymph nodes unmodified, wrapped up in small structures or vesicles (2). In this respect, the last few years have witnessed augmented understanding in microparticle function.Described over 50 years ago (reviewed in (3, 4), microparticles are heterogeneous in nature with their size varying between 0.2 and 1.0 μm, and are characterized by an outer membrane composed of a phospholipid bilayer and cell surface proteins. The mechanism of microparticle production is not fully understood, though it may follow processes not dissimilar from those observed in apoptosis, involving membrane detachment from the anchoring cytoskeleton and loss of membrane symmetry, which leads to exposure of negatively charged phospholipids (5–7). Proteins found on the outer leaflet of the microparticle cell membrane are believed to reflect both the origin and activation status of the parental cell (8, 9); for instance, microparticles from neutrophils express CD66b and CD62L (10, 11). We have recently identified the selective expression of the potent anti-inflammatory and proresolving protein Annexin A1 (ANXA1) on the surface of microparticles generated from neutrophils adherent to endothelial monolayers, when compared with those prepared from quiescent neutrophils (12). Microparticle production is not restricted to one subset of cells and using cell specific antigens the relative contribution of different cell types to the total microparticle population in a particular environment can be assessed. This has allowed for the analysis of different microparticle populations (the focus being by and large platelet- and endothelial-derived microparticles) in a number of pathologies in the quest to identify robust biomarkers for disease and treatment (13–15). With regard to inflammatory diseases, examples would include plasma samples in sepsis (16), psoriatic arthritis (17), and scleroderma (18). However, the vast majority of these studies have only determined microparticle expression patterns with respect to the cell type of origin, without addressing the possibility that microparticle composition—even when generated from the same leukocyte subset—might differ in relation to disease status and/or mode of cell activation. Of note recent work has also demonstrated that the production of neutrophil microparticles during self-limited inflammation is temporally regulated suggesting that these microparticles are important in orchestrating inflammation-resolution (1).Recent work has established that microparticles can elicit a variety of biological processes ranging from angiogenesis to anti-inflammation; so that it is very unlikely they can continue to be considered “cell debris,” as initially postulated. The following are some examples, relevant to the present study. Ingestion of platelet microparticles alters the phenotype of macrophages, leading to the false identification of endothelial cell progenitor cells in culture (19). Likewise, sonic hedgehog can be transferred, via microparticles, to dysfunctional endothelial cells, restoring the activity of nitric oxide synthase with downstream production of nitric oxide (20). Microparticles can carry functionally active receptor proteins to target cells (21, 22). Finally, in vivo generation of microparticles has been observed within the inflamed microcirculation. Real time analysis of leukocyte recruitment has visualized microparticle release from leukocytes squeezing through an endothelial barrier, providing evidence for their formation in vivo together with potential functional relevance in relation to cell migration (23).On stimulation, neutrophils produce microparticles with rapid and nongenomic anti-inflammatory properties, in vitro and in vivo, reliant on their expression of ANXA1 (12). Whereas these findings are consistent with those obtained by Gasser and colleagues (24) who described inhibitory properties of neutrophil microparticles, other studies have suggested that the same cell type can produce microparticles that elicit activating properties, for instance upon incubation with endothelial cells or monocytes for longer time-points (25, 26). Thus, to gain further insight into the potential mechanisms involved in mediating such distinct effects, we deemed it important to determine the total proteome of neutrophil microparticles. Having established that different stimulation conditions yield microparticle populations with distinct protein profiles, we corroborated our observations in two distinct clinical scenarios, characterizing neutrophil microparticles from skin blister exudates and plasma samples from sepsis patients using a select group of proteins identified in our proteomic profile. We also established that the two microparticles subsets differentially modulate endothelial cell gene expression profile and thereby function, as determined by connectivity map analysis.     

Molecular Evolution of Broadly Neutralizing Llama Antibodies to the CD4-Binding Site of HIV-1

To date, no immunization of humans or animals has elicited broadly neutralizing sera able to prevent HIV-1 transmission; however, elicitation of broad and potent heavy chain only antibodies (HCAb) has previously been reported in llamas. In this study, the anti-HIV immune responses in immunized llamas were studied via deep sequencing analysis using broadly neutralizing monoclonal HCAbs as a guides. Distinct neutralizing antibody lineages were identified in each animal, including two defined by novel antibodies (as variable regions called VHH) identified by robotic screening of over 6000 clones. The combined application of five VHH against viruses from clades A, B, C and CRF_AG resulted in neutralization as potent as any of the VHH individually and a predicted 100% coverage with a median IC50 of 0.17 µg/ml for the panel of 60 viruses tested. Molecular analysis of the VHH repertoires of two sets of immunized animals showed that each neutralizing lineage was only observed following immunization, demonstrating that they were elicited de novo. Our results show that immunization can induce potent and broadly neutralizing antibodies in llamas with features similar to human antibodies and provide a framework to analyze the effectiveness of immunization protocols.     

The competent sentinel node: an association with an axillary presentation and an occult or a small primary invasive breast carcinoma

The concept of the sentinel node describes a primary or sentinel lymph node (SLN), which exists and through which tumour cells from a primary tumour in a particular location must first travel to spread to a particular regional lymph node group. In this series we present three patients presenting with a pathological axillary node associated with either an occult or very small primary breast cancer. In each case the primary tumour was found to have metastasised to the palpable node, however despite the significant enlargement of this node, no other axillary nodes were found to be affected on axillary node clearance. This has led us to postulate that the SLN in some cases contains unique characteristics that enable it to prevent further spread of the tumour up the lymphatic chain. Hence the term the competent sentinel node.     

Spontaneous recovery in acute human hepatitis C virus infection: functional T-cell thresholds and relative importance of CD4 help

The mechanisms mediating protective immunity to hepatitis C virus (HCV) infection are incompletely understood because early infection in humans is rarely identified, particularly in those individuals who subsequently demonstrate spontaneous virus eradication. We have established a large national network of patients with acute HCV infection. Here, we comprehensively examined total HCV-specific CD4⁺ and CD8⁺ T-cell responses and identified functional T-cell thresholds that predict recovery. Interestingly, we found that the presence of HCV-specific cytotoxic T lymphocytes (CTLs) that can proliferate, exhibit cytotoxicity, and produce gamma interferon does not ensure recovery, but whether these CTLs were primed in the presence or absence of CD4⁺ T-cell help (HCV-specific interleukin-2 production) is a critical determinant. These results have important implications for early prediction of the virologic outcome following acute HCV and for the development of novel immunotherapeutic approaches.     

Functionally Important Carboxyls in a Bacterial Homologue of the Vesicular Monoamine Transporter (VMAT)

Transporters essential for neurotransmission in mammalian organisms and bacterial multidrug transporters involved in antibiotic resistance are evolutionarily related. To understand in more detail the evolutionary aspects of the transformation of a bacterial multidrug transporter to a mammalian neurotransporter and to learn about mechanisms in a milieu amenable for structural and biochemical studies, we identified, cloned, and partially characterized bacterial homologues of the rat vesicular monoamine transporter (rVMAT2). We performed preliminary biochemical characterization of one of them, Brevibacillus brevis monoamine transporter (BbMAT), from the bacterium B. brevis. BbMAT shares substrates with rVMAT2 and transports them in exchange with >1H⁺, like the mammalian transporter. Here we present a homology model of BbMAT that has the standard major facilitator superfamily fold; that is, with two domains of six transmembrane helices each, related by 2-fold pseudosymmetry whose axis runs normal to the membrane and between the two halves. The model predicts that four carboxyl residues, a histidine, and an arginine are located in the transmembrane segments. We show here that two of the carboxyls are conserved, equivalent to the corresponding ones in rVMAT2, and are essential for H⁺-coupled transport. We conclude that BbMAT provides an excellent experimental paradigm for the study of its mammalian counterparts and bacterial multidrug transporters.