A Strategy for O-Glycoproteomics of Enveloped Viruses—the O-Glycoproteome of Herpes Simplex Virus Type 1

Glycosylation of viral envelope proteins is important for infectivity and interaction with host immunity, however, our current knowledge of the functions of glycosylation is largely limited to N-glycosylation because it is difficult to predict and identify site-specific O-glycosylation. Here, we present a novel proteome-wide discovery strategy for O-glycosylation sites on viral envelope proteins using herpes simplex virus type 1 (HSV-1) as a model. We identified 74 O-linked glycosylation sites on 8 out of the 12 HSV-1 envelope proteins. Two of the identified glycosites found in glycoprotein B were previously implicated in virus attachment to immune cells. We show that HSV-1 infection distorts the secretory pathway and that infected cells accumulate glycoproteins with truncated O-glycans, nonetheless retaining the ability to elongate most of the surface glycans. With the use of precise gene editing, we further demonstrate that elongated O-glycans are essential for HSV-1 in human HaCaT keratinocytes, where HSV-1 produced markedly lower viral titers in HaCaT with abrogated O-glycans compared to the isogenic counterpart with normal O-glycans. The roles of O-linked glycosylation for viral entry, formation, secretion, and immune recognition are poorly understood, and the O-glycoproteomics strategy presented here now opens for unbiased discovery on all enveloped viruses.     

The influence of different glycosylation patterns on factor VII biological activity

In this study the bioactivity of three differently glycosylated blood coagulation factor VII (FVII) variants (human plasma FVII, recombinant human FVII produced in CHO and BHK cell cultures) were analyzed and compared. Surface plasmon resonance studies of FVII interaction with soluble and full length TF together with FVII autoactivation assays revealed that BHK-derived FVII has the highest bioactivity, while human plasma and CHO-derived FVII showed very similar bioactivity. The affinity of FVII variants to TF correlates with FVII autoactivation rates – the higher the affinity, the faster the autoactivation rate.     

Characterization and differentiation potential of rat ventral mesencephalic neuronal progenitor cells immortalized with SV40 large T antigen

Neuronal progenitor cells (NPCs) possess high potential for use in regenerative medicine. To overcome their limited mitotic competence, various immortalization strategies have been applied that allow their prolonged maintenance and expansion in vitro. Such immortalized cells can be used for the design and discovery of new cell-based therapies for neurodegenerative diseases, such as Parkinson’s disease. We immortalized rat ventral mesencephalic NPCs by using SV40 large T antigen (SV40Tag). All cell clones displayed a two- to three–fold higher proliferation rate compared with the primary cells. In order to induce dopaminergic differentiation of generated cell clones, both glial-derived neurotrophic factor and di-butyryl cyclic adenosine monophosphate were applied. Treated cells were then characterized regarding the expression of dopaminergic lineage markers, differentiation of various cell populations, calcium imaging in the presence of kainate, and immunohistochemistry after intrastriatal transplantation. Treated cells displayed morphological maturation, and calcium imaging revealed neuronal properties in the presence of kainate. These cells also expressed low mRNA levels of the dopamine transporter and tyrosine hydroxylase (TH), although no TH-immunopositive neurons were found. Intrastriatal transplantation into the neurotoxin-lesioned rats did not induce further differentiation. As an alternative approach, we silenced SV40Tag with short interfering RNA, but this was not sufficient to trigger differentiation into dopaminergic neurons. Nevertheless, neuronal and glial cells were detected as shown by β-tubulin type III and glial fibrillary acidic protein staining, respectively. SV40Tag cells are suitable for carrying out controlled genetic modifications as shown by overexpression of enhanced green fluorescence protein after efficient non-viral transfection.     

Incorporation of a polypeptide segment into the β-domain pore during the assembly of a bacterial autotransporter

Bacterial autotransporters consist of an N-terminal 'passenger domain' that is transported into the extracellular space by an unknown mechanism and a C-terminal 'β-domain' that forms a β-barrel in the outer membrane. Recent studies have revealed that fully assembled autotransporters have an unusual architecture in which a small passenger domain segment traverses the pore formed by the β-domain. It is unclear, however, whether this configuration forms prior to passenger domain translocation or results from the translocation of the passenger domain through the β-domain pore. By examining the accessibility of tobacco etch virus protease sites and single-cysteine residues in the passenger domain of the Escherichia coli O157:H7 autotransporter EspP at different stages of protein biogenesis, we identified a novel pre-translocation intermediate whose topology resembles that of the fully assembled protein. This intermediate was isolated in the periplasm in cell fractionation experiments. The data strongly suggest that the EspP β-domain and an embedded polypeptide segment are integrated into the outer membrane as a single pre-formed unit. The data also provide indirect evidence that at least some outer membrane proteins acquire considerable tertiary structure prior to their membrane integration.     

Hepatic cytochrome P450 enzymes belonging to the CYP2C subfamily from an Australian marsupial, the koala (Phascolarctos cinereus)

Cytochromes P450 (CYPs) are critically important in the oxidative metabolism of a diverse array of xenobiotics and endogenous substrates. We have previously reported that the obligate Eucalyptus feeder koala (Phascolarctos cinereus) exhibits a higher hepatic CYP2C activity as compared to non-Eucalyptus feeders human or rat, with stimulation of CYP2C activity by cineole. In the present study, we examine CYP2C expression by immunohistochemistry and describe the identification and cloning of koala CYP2Cs. Utilising anti-rat CYP2C6 antibody, the expression of CYP2C was found to be uniform across the hepatic sections, being consistent with that observed in human and rat. Two 1647 and 1638 bp koala liver CYP2C complete cDNAs, designated CYP2C47 and CYP2C48 respectively, were cloned by cDNA library screening. The koala CYP2C cDNAs encode a protein of 495 amino acids. Three additional partial CYP2C sequences were also identified from the koala, indicating the multiplicity of the CYP2C subfamily in this unique marsupial species. The results of this study demonstrate the presence of koala hepatic CYP2Cs that share several common features with other published CYP2Cs; however CYP2C47 and CYP2C48 contain four extra amino acid residues at the NH2-terminal, a transmembrane anchor which was reported being a fundamentally conserved structure core of all eukaryote CYP enzymes.     

Simultaneous determination of oleuropein and hydroxytyrosol in rat plasma using liquid chromatography with fluorescence detection

Oleuropein, the main glycoside present in olives, and hydroxytyrosol, the principal degradation product of oleuropein present in olive oil, have been linked to reduction of coronary heart disease and certain cancers. In the present study a direct and sensitive reversed-phase high-performance liquid chromatographic assay was developed for simultaneous quantification of both oleuropein and hydroxytyrosol. The plasma protein was precipitated with acetonitrile, samples were then centrifuged and supernatants were dried, and reconstituted with water prior to injection. The chromatographic analysis was carried out using a phenyl column and an isocratic elution of acidified water and acetonitrile with fluorescence detection at 281 and 316 nm for excitation and emission, respectively. The calibration curve was linear and limits of quantification were 30 ng/ml and 3 microg/ml for hydroxytyrosol and oleuropein, respectively. The method has been successfully applied to monitor oleuropein and hydroxytyrosol plasma levels in the rat.     

A Hypomorphic PALB2 Allele Gives Rise to an Unusual Form of FA-N Associated with Lymphoid Tumour Development

Patients with biallelic truncating mutations in PALB2 have a severe form of Fanconi anaemia (FA-N), with a predisposition for developing embryonal-type tumours in infancy. Here we describe two unusual patients from a single family, carrying biallelic PALB2 mutations, one truncating, c.1676_1677delAAinsG;(p.Gln559ArgfsTer2), and the second, c.2586+1G>A; p.Thr839_Lys862del resulting in an in frame skip of exon 6 (24 amino acids). Strikingly, the affected individuals did not exhibit the severe developmental defects typical of FA-N patients and initially presented with B cell non-Hodgkin lymphoma. The expressed p.Thr839_Lys862del mutant PALB2 protein retained the ability to interact with BRCA2, previously unreported in FA-N patients. There was also a large increased chromosomal radiosensitivity following irradiation in G2 and increased sensitivity to mitomycin C. Although patient cells were unable to form Rad51 foci following exposure to either DNA damaging agent, U2OS cells, in which the mutant PALB2 with in frame skip of exon 6 was induced, did show recruitment of Rad51 to foci following damage. We conclude that a very mild form of FA-N exists arising from a hypomorphic PALB2 allele.     

Review: Epidemiology of Helicobacter pylori infection

This review summarizes recent publications on the epidemiology of Helicobacter pylori. Two major systemic analyses, from Malaysia and Ethiopia, were published. The Brazilian Consensus Conference has stated that H pylori infection is an infectious disease with an indication for antimicrobial therapy. A continuous decrease in H pylori prevalence was reported from many regions worldwide, including Korea, China, Iran, and Austria. A cross‐sectional H pylori prevalence study conducted in the United Arab Emirates found 41% prevalence in a group of healthy children and adults. Several studies from Asia addressed H pylori prevalence in adults undergoing regular checkup. The largest of such studies, performed in Korea, involved 24 471 subjects and reported 41.5% seroprevalence. A relatively smaller study from East China on 3252 subjects reported 27.5% prevalence. In contrast, a study from Spain reported 87.2% seroprevalence. A report on the association between smoking and H pylori seropositivity was published on behalf of the Stomach Cancer Pooling (StoP) Project—a consortium of epidemiological studies of gastric cancer. Also, other potential risk factors, including occupational risk factors, water supply, and food were analyzed. Gastroesophageal reflux and sexual partners has been associated with a higher risk for H pylori acquisition, and gut microbiota was suggested to play a role in intrafamilial transmission of H pylori. Finally, in a few studies (from Mexico and Japan), the catalytic model for predicting the potential risk of acquiring H pylori infection in the future was used. As anticipated, a further decline in H pylori‐related disease was demonstrated by applying the modeling.