Rescue of a H3N2 Influenza Virus Containing a Deficient Neuraminidase Protein by a Hemagglutinin with a Low Receptor-Binding Affinity

Influenza viruses possess at their surface two glycoproteins, the hemagglutinin and the neuraminidase, of which the antagonistic functions have to be well balanced for the virus to grow efficiently. Ferraris et al. isolated in 2003–2004 viruses lacking both a NA gene and protein (H3NA- viruses) (Ferraris O., 2006, Vaccine, 24(44–46):6656-9). In this study we showed that the hemagglutinins of two of the H3NA- viruses have reduced affinity for SAα2.6Gal receptors, between 49 and 128 times lower than that of the A/Moscow/10/99 (H3N2) virus and no detectable affinity for SAα2.3Gal receptors. We also showed that the low hemagglutinin affinity of the H3NA- viruses compensates for the lack of NA activity and allows the restoration of the growth of an A/Moscow/10/99 virus deficient in neuraminidase. These observations increase our understanding of H3NA- viruses in relation to the balance between the functional activities of the neuraminidase and hemagglutinin

Mutations in STAMBP, encoding a deubiquitinating enzyme, cause microcephaly-capillary malformation syndrome

Microcephaly–capillary malformation (MIC-CAP) syndrome is characterized by severe microcephaly with progressive cortical atrophy, intractable epilepsy, profound developmental delay and multiple small capillary malformations on the skin. We used whole-exome sequencing of five patients with MIC-CAP syndrome and identified recessive mutations in STAMBP, a gene encoding the deubiquitinating (DUB) isopeptidase STAMBP (STAM-binding protein, also known as AMSH, associated molecule with the SH3 domain of STAM) that has a key role in cell surface receptor–mediated endocytosis and sorting. Patient cell lines showed reduced STAMBP expression associated with accumulation of ubiquitin-conjugated protein aggregates, elevated apoptosis and insensitive activation of the RAS-MAPK and PI3K-AKT-mTOR pathways. The latter cellular phenotype is notable considering the established connection between these pathways and their association with vascular and capillary malformations. Furthermore, our findings of a congenital human disorder caused by a defective DUB protein that functions in endocytosis implicates ubiquitin-conjugate aggregation and elevated apoptosis as factors potentially influencing the progressive neuronal loss underlying MIC-CAP syndrome

Structure of Herpes Simplex Virus Glycoprotein D Bound to the Human Receptor Nectin-1

Binding of herpes simplex virus (HSV) glycoprotein D (gD) to a cell surface receptor is required to trigger membrane fusion during entry into host cells. Nectin-1 is a cell adhesion molecule and the main HSV receptor in neurons and epithelial cells. We report the structure of gD bound to nectin-1 determined by x-ray crystallography to 4.0 Å resolution. The structure reveals that the nectin-1 binding site on gD differs from the binding site of the HVEM receptor. A surface on the first Ig-domain of nectin-1, which mediates homophilic interactions of Ig-like cell adhesion molecules, buries an area composed by residues from both the gD N- and C-terminal extensions. Phenylalanine 129, at the tip of the loop connecting β-strands F and G of nectin-1, protrudes into a groove on gD, which is otherwise occupied by C-terminal residues in the unliganded gD and by N-terminal residues in the gD/HVEM complex. Notably, mutation of Phe129 to alanine prevents nectin-1 binding to gD and HSV entry. Together these data are consistent with previous studies showing that gD disrupts the normal nectin-1 homophilic interactions. Furthermore, the structure of the complex supports a model in which gD-receptor binding triggers HSV entry through receptor-mediated displacement of the gD C-terminal region

Acrolein Induces Endoplasmic Reticulum Stress and Causes Airspace Enlargement

BACKGROUND: Given the relative abundance and toxic potential of acrolein in inhaled cigarette smoke, it is surprising how little is known about the pulmonary and systemic effects of acrolein. Here we test the hypothesis whether systemic administration of acrolein could cause endoplasmic reticulum (ER) stress, and lung cell apoptosis, leading to the enlargement of the alveolar air spaces in rats. METHODS: Acute and chronic effects of intraperitoneally administered acrolein were tested. Mean alveolar airspace area was measured by using light microscopy and imaging system software. TUNEL staining and immunohistochemistry (IHC) for active caspase 3 and Western blot analysis for active caspase 3, and caspase 12 were performed to detect apoptosis. The ER-stress related gene expression in the lungs was determined by Quantitative real-time PCR analysis. Acrolein-protein adducts in the lung tissue were detected by IHC. RESULTS: Acute administration of acrolein caused a significant elevation of activated caspase 3, upregulation of VEGF expression and induced ER stress proteins in the lung tissue. The chronic administration of acrolein in rats led to emphysematous lung tissue remodeling. TUNEL staining and IHC for cleaved caspase 3 showed a large number of apoptotic septal cells in the acrolein-treated rat lungs. Chronic acrolein administration cause the endoplasmic reticulum stress response manifested by significant upregulation of ATF4, CHOP and GADd34 expression. In smokers with COPD there was a considerable accumulation of acrolein-protein adducts in the inflammatory, airway and vascular cells. CONCLUSIONS: Systemic administration of acrolein causes endoplasmic reticulum stress response, lung cell apoptosis, and chronic administration leads to the enlargement of the alveolar air spaces and emphysema in rats. The substantial accumulation of acrolein-protein adducts in the lungs of COPD patients suggest a role of acrolein in the pathogenesis of emphysema

The Princeton Protein Orthology Database (P-POD): A Comparative Genomics Analysis Tool for Biologists

Many biological databases that provide comparative genomics information and tools are now available on the internet. While certainly quite useful, to our knowledge none of the existing databases combine results from multiple comparative genomics methods with manually curated information from the literature. Here we describe the Princeton Protein Orthology Database (P-POD, http://ortholog.princeton.edu), a user-friendly database system that allows users to find and visualize the phylogenetic relationships among predicted orthologs (based on the OrthoMCL method) to a query gene from any of eight eukaryotic organisms, and to see the orthologs in a wider evolutionary context (based on the Jaccard clustering method). In addition to the phylogenetic information, the database contains experimental results manually collected from the literature that can be compared to the computational analyses, as well as links to relevant human disease and gene information via the OMIM, model organism, and sequence databases. Our aim is for the P-POD resource to be extremely useful to typical experimental biologists wanting to learn more about the evolutionary context of their favorite genes. P-POD is based on the commonly used Generic Model Organism Database (GMOD) schema and can be downloaded in its entirety for installation on one's own system. Thus, bioinformaticians and software developers may also find P-POD useful because they can use the P-POD database infrastructure when developing their own comparative genomics resources and database tools

aHUS caused by complement dysregulation: new therapies on the horizon

Atypical hemolytic uremic syndrome (aHUS) is a heterogeneous disease that is caused by defective complement regulation in over 50% of cases. Mutations have been identified in genes encoding both complement regulators [complement factor H (CFH), complement factor I (CFI), complement factor H-related proteins (CFHR), and membrane cofactor protein (MCP)], as well as complement activators [complement factor B (CFB) and C3]. More recently, mutations have also been identified in thrombomodulin (THBD), an anticoagulant glycoprotein that plays a role in the inactivation of C3a and C5a. Inhibitory autoantibodies to CFH account for an additional 5–10% of cases and can occur in isolation or in association with mutations in CFH, CFI, CFHR 1, 3, 4, and MCP. Plasma therapies are considered the mainstay of therapy in aHUS secondary to defective complement regulation and may be administered as plasma infusions or plasma exchange. However, in certain cases, despite initiation of plasma therapy, renal function continues to deteriorate with progression to end-stage renal disease and renal transplantation. Recently, eculizumab, a humanized monoclonal antibody against C5, has been described as an effective therapeutic strategy in the management of refractory aHUS that has failed to respond to plasma therapy. Clinical trials are now underway to further evaluate the efficacy of eculizumab in the management of both plasma-sensitive and plasma-resistant aHUS

Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency

BACKGROUND: Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions. OBJECTIVE: To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management. DATA SOURCES: Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach. KEY RECOMMENDATIONS: We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early