Project description:Our lab has previously used the Glyco v3 gene-chip to analyze RNA from human macrophages and T-cells, as part of a project examining the effect of cellular origin on the viral infectivity of HIV/SIV. Our experiments have led us to hypothesize that the different glycosylation pathways present in macrophages and T-cells result in the production of virions with differently glycosylated viral proteins and different glycans present on the virion surface. Furthermore, studies with glycosidases using the Glyco v3 gene-chip have indicated that these differences in the glycosylation profiles of virions derived from different cell types may influence viral infectivity. Here we used glyco v3 chips for identifying the enzymes active in the glycosylation pathways of 174xCEM and 293 cells, which are cell types commonly used in HIV and SIV research. These analyses will allow us a better understanding of the role of glycans and glycosylation in cell-type specific effects on viral infectivity because there is a much larger amount of data on virus derived from these cell types and we will be able to relate our studies more directly to previous work in our lab and other labs. RNA from 174xCEM and HEK293 cells, cell types commonly used in HIV and SIV research, was isolated and sent to Microarray Core (E). RNA was prepared in duplicate, totaling 4 samples. Samples were labeled and hybridized to the GLYCOv3 array and gene expression patterns were used to identify enzymes active in glycosylation pathways.
Project description:Our lab has previously used the Glyco v3 gene-chip to analyze RNA from human macrophages and T-cells, as part of a project examining the effect of cellular origin on the viral infectivity of HIV/SIV. Our experiments have led us to hypothesize that the different glycosylation pathways present in macrophages and T-cells result in the production of virions with differently glycosylated viral proteins and different glycans present on the virion surface. Furthermore, studies with glycosidases using the Glyco v3 gene-chip have indicated that these differences in the glycosylation profiles of virions derived from different cell types may influence viral infectivity.
Project description:The Fox laboratory studies the SIV infection of rhesus monkeys as a model for HIV/AIDS, focusing on central nervous system infection, immunity, and brain dysfunction that develops following infection. Previous Fox lab data shows that virions derived from macrophages and T-cells differ in infectivity in a manner based solely on their cellular origin, and that these differences can be influenced by the removal of various glycans from the surface proteins present on the virion. This study examines the glycosylation pathways functioning in human macrophages and T-cells, in the context of examining how differences in the glycosylation pathways in these cell types might influence the infectivity of viral particles derived from macrophages vs. those derived from T-cells. RNA was prepared from uninfected, activated a) human macrophages and b) T-cells and sent to Microarray Core (E). Samples were prepared in triplicate, with 3 biological replicates from each cell type. The RNA was amplified, labeled, and hybridized to the GLYCOv3 microarrays. Data was analyzed to determine the active glycosylation pathways in these cell types.
Project description:The Fox laboratory studies the SIV infection of rhesus monkeys as a model for HIV/AIDS, focusing on central nervous system infection, immunity, and brain dysfunction that develops following infection. Previous Fox lab data shows that virions derived from macrophages and T-cells differ in infectivity in a manner based solely on their cellular origin, and that these differences can be influenced by the removal of various glycans from the surface proteins present on the virion. This study examines the glycosylation pathways functioning in human macrophages and T-cells, in the context of examining how differences in the glycosylation pathways in these cell types might influence the infectivity of viral particles derived from macrophages vs. those derived from T-cells.
Project description:Ebola virus glycoprotein is one of the most heavily O-glycosylated viral envelope glycoproteins. The glycoprotein possesses a large mucin-like domain responsible for the cytopathic effect on infected cells, yet its structure or potential role in early entry events is poorly defined. To understand the importance of O-glycans and the individual O-glycosylation sites for viral infectivity, we performed a comprehensive characterization of site-specific glycosylation governed by the three key GalNAc-transferases, GalNAc-T1, -T2, and -T3, initiating O-glycan biosynthesis. Using TMT isobaric labelling we performed quantitative differential O-glycoproteomics on proteins produced in wild type HEK293 cells and cell lines ablated for each of the three GalNAc-Ts, as well as compared it to patterns on wild type virus-like particles. In total we found 38 and 41 O-glycosites on virus like particle-derived and recombinant GP, respectively, with well correlated sites and site-specific structures. Examination of the isoform-specific glycosylation demonstrate selective initiation of a subset of O-glycosites by each enzyme, with GalNAc-T1 having the largest contribution. We next demonstrate that O-linked glycan truncation and perturbed initiation retarded the production of viral particles and decreased infectivity of progeny virus. This work represents a comprehensive site-specific analysis of EBOV GP and sheds light on differential regulation of EBOV GP glycosylation initiated by host GalNAc-Ts. Together with the effect on viral propagation it opens prospective avenues for tailored intervention approaches and means for modulating immunogen O-glycan density.
Project description:The densely glycosylated spike (S) proteins that are highly exposed on the surface of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) facilitate viral attachment, entry, and membrane fusion. We have previously reported all the 22 N-glycosites and site-specific N-glycans in the S protein protomer. Herein, we report the comprehensive site-specific O-glycosylation landscapes of SARS-CoV-2 S proteins, which were characterized using high-resolution mass spectrometry. Following digestion using trypsin and trypsin/Glu-C, and de-N-glycosylation using PNGase F, we determined the mucin-type (GalNAc-type) O-glycosylation pattern of S proteins, including O-glycosites and the 6 most common O-glycans occupying them, via Byonic identification and manual validation. Finally, 43 O-glycosites were identified by higher energy collision-induced dissociation (HCD), and 11 O-glycosites were verified by electron transfer/higher energy collision-induced dissociation (EThcD) in the insect cell-expressed S protein. Most glycosites were modified by non-sialylated O-glycans such as HexNAc(1) and HexNAc(1)Hex(1). In contrast, 30 O-glycosites were identified by HCD, and 14 O-glycosites were verified by EThcD in the human cell-expressed S protein S1 subunit. Most glycosites were modified by sialylated O-glycans such as HexNAc(1)Hex(1)NeuAc(1) and HexNAc(1)Hex(1)NeuAc(2). Our results are the first to reveal that the SARS-CoV-2 S protein is a mucin-type glycoprotein; clustered O-glycans often occur in the N- and the C-termini of the S protein, and the O-glycosite and O-glycan compositions vary with the host cell type. These site-specific O-glycosylation landscapes of the SARS-CoV-2 S protein are expected to provide novel insights into the viral binding mechanism and present a strategy for the development of vaccines and targeted drugs.
Project description:Human serum IgM antibodies are composed of heavily glycosylated polymers with five glycosylation sites on the μ (heavy) chain and one glycosylation site on the J chain. In contrast to IgG glycans, which are vital for a number of biological functions, virtually nothing is known about structure-function relationships of IgM glycans. Natural IgM is the earliest immunoglobulin produced and recognizes multiple antigens with low affinity, whilst immune IgM is induced by antigen exposure and is characterized by a higher antigen specificity. Natural anti-lymphocyte IgM is present in the serum of healthy individuals and increases in inflammatory conditions. It is able to inhibit T cell activation, but the underlying molecular mechanism is not understood. Here we show, for the first time, that sialylated N-linked glycans induce the internalization of IgM by T cells, which in turn causes severe inhibition of T cell responses. The absence of sialic acid residues abolishes these inhibitory activities, showing a key role of sialylated N-glycans in inducing the IgM-mediated immune suppression.
Project description:Various cancers such as colorectal cancer (CRC) are associated with alterations in protein glycosylation. CRC cell lines are frequently used to study these (glyco)biological changes and their mechanisms. However, differences between CRC cell lines with regard to their glycosylation have hitherto been largely neglected. Here, we comprehensively characterized the N-glycan profiles of 25 different CRC cell lines, derived from primary tumors and metastatic sites, in order to investigate their potential as glycobiological tumor model systems and to reveal glycans associated with cell line phenotypes. We applied an optimized, high-throughput membrane-based enzymatic glycan release for small sample amounts. Released glycans were derivatized to stabilize and differentiate between a2,3- and a2,6-linked N-acetylneuraminic acids, followed by N-glycosylation analysis by MALDI-TOF(/TOF)-MS. Our results showed pronounced differences between the N-glycosylation patterns of CRC cell lines. CRC cell line profiles differed from tissue-derived N-glycan profiles with regard to their high-mannose N-glycan content but showed a large overlap for complex type N-glycans, supporting their use as a glycobiological cancer model system. Importantly, we could show that the high-mannose N-glycans did not only occur as intracellular precursors but were also present at the cell surface. The obtained CRC cell line N-glycan features were not clearly correlated with mRNA expression levels of glycosyltransferases, demonstrating the usefulness of performing the structural analysis of glycans. Finally, correlation of CRC cell line glycosylation features with cancer cell markers and phenotypes revealed an association between highly fucosylated glycans and CDX1 and/or villin mRNA expression that both correlate with cell differentiation. Together, our findings provide new insights into CRC-associated glycan changes and setting the basis for more in-depth experiments on glycan function and regulation.
Project description:FOXA1 and FOXA2 are essentail transcription factors for proper gut development. In adults, they play a role in the differentiation of intestinal secretory cells and were also reporeted to directly activate Muc2 transcription. Here we show that FOXA1 and FOXA2 bind near goblet cell genes, and are specifically enriched near glycosylation genes. Deletion of these transcription factors in mouse intestine leads to a downregulation of glycosylation genes in the colon and to a massive change of the colonic surface glycans. I turn, the microbiome composition shifts dramatically and spontaneous inflammatory bowel disease ensued. We conclude that vertebrates shape a favorable microbiome by establishing a glycocalyx to nurture specific bacterial taxa through control of the epithelial glycosylation program by the FoxA transcription factors.
Project description:FOXA1 and FOXA2 are essentail transcription factors for proper gut development. In adults, they have a role in the differentiation of intestinal secretory cell lineages and were also reporeted to directly activate Muc2 transcription. Here we show that deletion of Foxa1 and Foxa2 in mouse intestinal epithelium leads to a downregulation of glycosylation genes in the colon and to a massive change of the colonic surface glycans. In turn, the microbiome composition shifts dramatically and spontaneous inflammatory bowel disease ensued. We conclude that vertebrates shape a favorable microbiome by establishing a glycocalyx to nurture specific bacterial taxa through control of the epithelial glycosylation program by the FoxA transcription factors.