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Glycobiology Oct 2023While glycans underlie many biological processes, such as protein folding, cell adhesion, and cell-cell recognition, deep evolution of glycosylation machinery remains an...
While glycans underlie many biological processes, such as protein folding, cell adhesion, and cell-cell recognition, deep evolution of glycosylation machinery remains an understudied topic. N-linked glycosylation is a conserved process in which mannosidases are key trimming enzymes. One of them is the glycoprotein endo-α-1,2-mannosidase which participates in the initial trimming of mannose moieties from an N-linked glycan inside the cis-Golgi. It is unique as the only endo-acting mannosidase found in this organelle. Relatively little is known about its origins and evolutionary history; so far it was reported to occur only in vertebrates. In this work, a taxon-rich bioinformatic survey to unravel the evolutionary history of this enzyme, including all major eukaryotic clades and a wide representation of animals, is presented. The endomannosidase was found to be more widely distributed in animals and other eukaryotes. The protein motif changes in context of the canonical animal enzyme were tracked. Additionally, the data show the two canonical vertebrate endomannosidase genes, MANEA and MANEAL, arose at the second round of the two vertebrate genome duplications and one more vertebrate paralog, CMANEAL, is uncovered. Finally, a framework where N-glycosylation co-evolved with complex multicellularity is described. A better understanding of the evolution of core glycosylation pathways is pivotal to understanding biology of eukaryotes in general, and the Golgi apparatus in particular. This systematic analysis of the endomannosidase evolution is one step toward this goal.
Topics: Animals; alpha-Mannosidase; Phylogeny; Mannosidases; Polysaccharides; Glycosylation; Vertebrates; Eukaryota; Golgi Apparatus
PubMed: 37202179
DOI: 10.1093/glycob/cwad041 -
Analytical and Bioanalytical Chemistry Jul 2023This trends article provides an overview of the state of the art in the analysis of intact glycopeptides by proteomics technologies based on LC-MS analysis. A brief... (Review)
Review
This trends article provides an overview of the state of the art in the analysis of intact glycopeptides by proteomics technologies based on LC-MS analysis. A brief description of the main techniques used at the different steps of the analytical workflow is provided, giving special attention to the most recent developments. The topics discussed include the need for dedicated sample preparation for intact glycopeptide purification from complex biological matrices. This section covers the common approaches with a special description of new materials and innovative reversible chemical derivatization strategies, specifically devised for intact glycopeptide analysis or dual enrichment of glycosylation and other post-translational modifications. The approaches are described for the characterization of intact glycopeptide structures by LC-MS and data analysis by bioinformatics for spectra annotation. The last section covers the open challenges in the field of intact glycopeptide analysis. These challenges include the need of a detailed description of the glycopeptide isomerism, the issues with quantitative analysis, and the lack of analytical methods for the large-scale characterization of glycosylation types that remain poorly characterized, such as C-mannosylation and tyrosine O-glycosylation. This bird's-eye view article provides both a state of the art in the field of intact glycopeptide analysis and open challenges to prompt future research on the topic.
Topics: Chromatography, Liquid; Glycopeptides; Glycosylation; Mass Spectrometry; Protein Processing, Post-Translational
PubMed: 36811677
DOI: 10.1007/s00216-023-04592-z -
International Journal of Oral Science Mar 2024SEMA7A belongs to the Semaphorin family and is involved in the oncogenesis and tumor progression. Aberrant glycosylation has been intricately linked with immune escape...
SEMA7A belongs to the Semaphorin family and is involved in the oncogenesis and tumor progression. Aberrant glycosylation has been intricately linked with immune escape and tumor growth. SEMA7A is a highly glycosylated protein with five glycosylated sites. The underlying mechanisms of SEMA7A glycosylation and its contribution to immunosuppression and tumorigenesis are unclear. Here, we identify overexpression and aberrant N-glycosylation of SEMA7A in head and neck squamous cell carcinoma, and elucidate fucosyltransferase FUT8 catalyzes aberrant core fucosylation in SEMA7A at N-linked oligosaccharides (Asn 105, 157, 258, 330, and 602) via a direct protein‒protein interaction. A glycosylated statue of SEMA7A is necessary for its intra-cellular trafficking from the cytoplasm to the cytomembrane. Cytokine EGF triggers SEMA7A N-glycosylation through increasing the binding affinity of SEMA7A toward FUT8, whereas TGF-β1 promotes abnormal glycosylation of SEMA7A via induction of epithelial-mesenchymal transition. Aberrant N-glycosylation of SEMA7A leads to the differentiation of CD8 T cells along a trajectory toward an exhausted state, thus shaping an immunosuppressive microenvironment and being resistant immunogenic cell death. Deglycosylation of SEMA7A significantly improves the clinical outcome of EGFR-targeted and anti-PD-L1-based immunotherapy. Finally, we also define RBM4, a splice regulator, as a downstream effector of glycosylated SEMA7A and a pivotal mediator of PD-L1 alternative splicing. These findings suggest that targeting FUT8-SEMA7A axis might be a promising strategy for improving antitumor responses in head and neck squamous cell carcinoma patients.
Topics: Humans; Glycosylation; Squamous Cell Carcinoma of Head and Neck; CD8-Positive T-Lymphocytes; Fucosyltransferases; Head and Neck Neoplasms; Tumor Microenvironment; RNA-Binding Proteins; Antigens, CD; Semaphorins; GPI-Linked Proteins
PubMed: 38548747
DOI: 10.1038/s41368-024-00289-w -
Scientific Reports Apr 2024Evolution shapes protein sequences for their functions. Here, we studied the moonlighting functions of the N-linked sequon NXS/T, where X is not P, in human...
Evolution shapes protein sequences for their functions. Here, we studied the moonlighting functions of the N-linked sequon NXS/T, where X is not P, in human nucleocytosolic proteins. By comparing membrane and secreted proteins in which sequons are well known for N-glycosylation, we discovered that cyto-sequons can participate in nucleic acid binding, particularly in zinc finger proteins. Our global studies further discovered that sequon occurrence is largely proportional to protein length. The contribution of sequons to protein functions, including both N-glycosylation and nucleic acid binding, can be regulated through their density as well as the biased usage between NXS and NXT. In proteins where other PTMs or structural features are rich, such as phosphorylation, transmembrane ɑ-helices, and disulfide bridges, sequon occurrence is scarce. The information acquired here should help understand the relationship between protein sequence and function and assist future protein design and engineering.
Topics: Humans; Proteins; Glycosylation; Amino Acid Sequence; Phosphorylation; Nucleic Acids
PubMed: 38565583
DOI: 10.1038/s41598-024-57334-1 -
Nature Communications Oct 2023The neurofilament (NF) cytoskeleton is critical for neuronal morphology and function. In particular, the neurofilament-light (NF-L) subunit is required for NF assembly...
The neurofilament (NF) cytoskeleton is critical for neuronal morphology and function. In particular, the neurofilament-light (NF-L) subunit is required for NF assembly in vivo and is mutated in subtypes of Charcot-Marie-Tooth (CMT) disease. NFs are highly dynamic, and the regulation of NF assembly state is incompletely understood. Here, we demonstrate that human NF-L is modified in a nutrient-sensitive manner by O-linked-β-N-acetylglucosamine (O-GlcNAc), a ubiquitous form of intracellular glycosylation. We identify five NF-L O-GlcNAc sites and show that they regulate NF assembly state. NF-L engages in O-GlcNAc-mediated protein-protein interactions with itself and with the NF component α-internexin, implying that O-GlcNAc may be a general regulator of NF architecture. We further show that NF-L O-GlcNAcylation is required for normal organelle trafficking in primary neurons. Finally, several CMT-causative NF-L mutants exhibit perturbed O-GlcNAc levels and resist the effects of O-GlcNAcylation on NF assembly state, suggesting a potential link between dysregulated O-GlcNAcylation and pathological NF aggregation. Our results demonstrate that site-specific glycosylation regulates NF-L assembly and function, and aberrant NF O-GlcNAcylation may contribute to CMT and other neurodegenerative disorders.
Topics: Humans; Charcot-Marie-Tooth Disease; Intermediate Filaments; Mutation; Glycosylation; Acetylglucosamine; Protein Processing, Post-Translational
PubMed: 37848414
DOI: 10.1038/s41467-023-42227-0 -
Postepy Biochemii Sep 2023Glycosylated proteins play a key role in the various stages of bacterial and viral invasions. Glycosylation is a common process across all domains of life. Initially,...
Glycosylated proteins play a key role in the various stages of bacterial and viral invasions. Glycosylation is a common process across all domains of life. Initially, this process was attributed only to eukaryotic organisms, in which the synthesis takes place in the rough endoplasmic reticulum and the Golgi apparatus. Over time, it has been shown that many bacteria and viruses express N-glycans and O-glycans on their surface. Prokaryotes are able to synthesize glycans, while virions take over the host's cellular machinery to produce glycans. Pathogens use glycoproteins to regulate adhesion to infected cells (Ebola virus), protect receptor-binding epitopes (HIV) and evade the immune system detection by molecular mimicry (Helicobacter pylori, Haemophilus influenzae). Successful infection also depends on the host surface glycans, mainly in determining the tissue tropism of viruses (Influenza A viruses) and the sliding motility of bacteria (Mycoplasma sp.). Modification of glycan structures, important at various levels of the infectious cycle, creates new therapeutic possibilities that gives a chance to limit the spread of infectious diseases.
Topics: Humans; Glycosylation; Viruses; Polysaccharides; Virus Diseases; Bacteria
PubMed: 38019747
DOI: 10.18388/pb.2021_488 -
Platelets Dec 2023gene encodes the uridine diphosphate [UDP]-galactose-4-epimerase, which catalyzes the bidirectional interconversion of UDP-glucose to UDP-galactose, and...
gene encodes the uridine diphosphate [UDP]-galactose-4-epimerase, which catalyzes the bidirectional interconversion of UDP-glucose to UDP-galactose, and UDP-N-acetyl-glucosamine to UDP-N-acetyl-galactosamine. In that way, GALE balances, through reversible epimerization, the pool of four sugars that are essential during the biosynthesis of glycoproteins and glycolipids. -related disorder presents an autosomal recessive inheritance pattern, and it is commonly associated with galactosemia. Peripheral galactosemia generally associates with non-generalized forms or even asymptomatic presentations, while classical galactosemia may be related to complications such as learning difficulties, developmental delay, cardiac failure, or dysmorphic features. Recently, variants have been related to severe thrombocytopenia, pancytopenia, and in one patient, to myelodysplastic syndrome.
Topics: Humans; Galactose; Galactosemias; Hemorrhage; Thrombocytopenia; UDPglucose 4-Epimerase
PubMed: 36846897
DOI: 10.1080/09537104.2023.2176699 -
Bioengineering (Basel, Switzerland) Jul 2023Genetic screen technology has been applied to study the mechanism of action of bacterial toxins-a special class of virulence factors that contribute to the pathogenesis... (Review)
Review
Genetic screen technology has been applied to study the mechanism of action of bacterial toxins-a special class of virulence factors that contribute to the pathogenesis caused by bacterial infections. These screens aim to identify host factors that directly or indirectly facilitate toxin intoxication. Additionally, specific properties of certain toxins, such as membrane interaction, retrograde trafficking, and carbohydrate binding, provide robust probes to comprehensively investigate the lipid biosynthesis, membrane vesicle transport, and glycosylation pathways, respectively. This review specifically focuses on recent representative toxin-based genetic screens that have identified new players involved in and provided new insights into fundamental biological pathways, such as glycosphingolipid biosynthesis, protein glycosylation, and membrane vesicle trafficking pathways. Functionally characterizing these newly identified factors not only expands our current understanding of toxin biology but also enables a deeper comprehension of fundamental biological questions. Consequently, it stimulates the development of new therapeutic approaches targeting both bacterial infectious diseases and genetic disorders with defects in these factors and pathways.
PubMed: 37627769
DOI: 10.3390/bioengineering10080884 -
Cellular and Molecular Gastroenterology... 2024
Topics: Glycosylation; Lipid Metabolism; Liver; Humans; Animals; Sugars
PubMed: 38583483
DOI: 10.1016/j.jcmgh.2024.03.010 -
Cells Jul 2023The Golgi apparatus plays a central role in protein sorting, modification and trafficking within cells; its dysregulation has been implicated in various cancers... (Review)
Review
The Golgi apparatus plays a central role in protein sorting, modification and trafficking within cells; its dysregulation has been implicated in various cancers including those affecting the GI tract. This review highlights two Golgi target proteins, namely GOLPH3 and GOLGA proteins, from this apparatus as they relate to gastroenterological cancers. GOLPH3-a highly conserved protein of the trans-Golgi network-has become a key player in cancer biology. Abnormal expression of GOLPH3 has been detected in various gastrointestinal cancers including gastric, colorectal and pancreatic cancers. GOLPH3 promotes tumor cell proliferation, survival, migration and invasion via various mechanisms including activating the PI3K/Akt/mTOR signaling pathway as well as altering Golgi morphology and vesicular trafficking. GOLGA family proteins such as GOLGA1 (golgin-97) and GOLGA7 (golgin-84) have also been implicated in gastroenterological cancers. GOLGA1 plays an essential role in protein trafficking within the Golgi apparatus and has been associated with poor patient survival rates and increased invasiveness; GOLGA7 maintains Golgi structure while having been shown to affect protein glycosylation processes. GOLPH3 and GOLGA proteins play a pivotal role in gastroenterological cancer, helping researchers unlock molecular mechanisms and identify therapeutic targets. Their dysregulation affects various cellular processes including signal transduction, vesicular trafficking and protein glycosylation, all contributing to tumor aggressiveness and progression.
Topics: Humans; Phosphatidylinositol 3-Kinases; Membrane Proteins; Neoplasms; Golgi Apparatus; Gastrointestinal Tract
PubMed: 37508488
DOI: 10.3390/cells12141823