Identification of a Conserved Glycan Signature for Microvesicles

Institute for Cellular and Molecular Biology, The University of Texas at Austin , 1 University Station, Austin, Texas 78712-0159, United States.
Journal of Proteome Research (Impact Factor: 4.25). 08/2011; 10(10):4624-33. DOI: 10.1021/pr200434y
Source: PubMed


Microvesicles (exosomes) are important mediators of intercellular communication, playing a role in immune regulation, cancer progression, and the spread of infectious agents. The biological functions of these small vesicles are dependent on their composition, which is regulated by mechanisms that are not well understood. Although numerous proteomic studies of these particles exist, little is known about their glycosylation. Carbohydrates are involved in protein trafficking and cellular recognition. Glycomic analysis may thus provide valuable insights into microvesicle biology. In this study, we analyzed glycosylation patterns of microvesicles derived from a variety of biological sources using lectin microarray technology. Comparison of the microvesicle glycomes with their parent cell membranes revealed both enrichment and depletion of specific glycan epitopes in these particles. These include enrichment in high mannose, polylactosamine, α-2,6 sialic acid, and complex N-linked glycans and exclusion of terminal blood group A and B antigens. The polylactosamine signature derives from distinct glycoprotein cohorts in microvesicles of different origins. Taken together, our data point to the emergence of microvesicles from a specific membrane microdomain, implying a role for glycosylation in microvesicle protein sorting.

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Available from: Karen D Hendricks-Muñoz, Sep 29, 2014
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    • "Exosome glycan profiles of different cell sources, such as T-cells, melanoma and colon cancer cells, and biological fluids like breast milk, are very similar, although they conserve some features of their parent membranes (13). The carbohydrate fingerprint detected in exosomes is less diverse than that observed in parent cells, but correspond to a conserved fraction of the parent cellular membrane that display a particular glycan profile (13). The variability observed between cellular and exosomal carbohydrate signatures has been suggested to indicate different membrane microdomain origins of these vesicles (13). "
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    ABSTRACT: Exosomes mediate intercellular communication and participate in many cell processes such as cancer progression, immune activation or evasion, and the spread of infection. Exosomes are small vesicles secreted to the extracellular environment through the release of intraluminal vesicles contained in multivesicular bodies (MVBs) upon the fusion of these MVBs with the plasma membrane. The composition of exosomes is not random, suggesting that the incorporation of cargo into them is a regulated process. However, the mechanisms that control the sorting of protein cargo into exosomes are currently elusive. Here, we review the post-translational modifications detected in exosomal proteins, and discuss their possible role in their specific sorting into exosomes.
    Frontiers in Immunology 08/2014; 5:383. DOI:10.3389/fimmu.2014.00383
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    • "Recently, Batista et al utilized a lectin array to study the glycomes of EVs harvested from several different sources.103 They showed differences between the cell surface glycomes and the resulting EV glycomes, which tended to be conserved, although there were distinguishing features in the gross glycomic compositions. "
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    ABSTRACT: Glioblastoma multiforme (GBM) is the most frequent and most devastating of the primary central nervous system tumors, with few patients living beyond 2 years postdiagnosis. The damage caused by the disease and our treatments for the patients often leave them physically and cognitively debilitated. Generally, GBMs appear after very short clinical histories and are discovered by imaging (using magnetic resonance imaging [MRI]), and the diagnosis is validated by pathology, following surgical resection. The treatment response and diagnosis of tumor recurrence are also tracked by MRI, but there are numerous problems encountered with these monitoring modalities, such as ambiguous interpretation and forms of pseudoprogression. Diagnostic, prognostic, and predictive biomarkers would be an immense boon in following treatment schemes and in determining recurrence, which often requires an invasive intracranial biopsy to verify imaging data. Extracellular vesicles (EVs) are stable, membrane-enclosed, virus-sized particles released from either the cell surface or from endosomal pathways that lead to the systemic release of EVs into accessible biofluids, such as serum/plasma, urine, cerebrospinal fluid, and saliva. EVs carry a wide variety of proteins, nucleic acids, lipids, and other metabolites, with many common features but with enough individuality to be able to identify the cell of origin of the vesicles. These components, if properly interrogated, could allow for the identification of tumor-derived EVs in biofluids, indicating tumor progression, relapse, or treatment failure. That knowledge would allow clinicians to continue with treatment regimens that were actually effective or to change course if the therapies were failing. Here, we review the features of GBM EVs, in terms of EV content and activities that may lead to the use of EVs as serially accessible biomarkers for diagnosis and treatment response in neuro-oncology.
    Pharmacogenomics and Personalized Medicine 02/2014; 7(1):65-77. DOI:10.2147/PGPM.S39768
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    • "This is in agreement with other reports where the enrichment of complex N-linked glycans into tumor microvesicles has been found [10]. However, exosomes also contained high mannose glycans, which is in agreement with the finding of this type of structures in urinary exovesicles [32] and in tumor microvesicles [10]. Initial results from our laboratory have indicated higher amounts of sialylated glycans by NP-HPLC in the exosomes relatively to plasma membrane or microsomal fraction (results not shown). "
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    ABSTRACT: Exosomes consist of vesicles that are secreted by several human cells, including tumor cells and neurons, and they are found in several biological fluids. Exosomes have characteristic protein and lipid composition, however, the results concerning glycoprotein composition and glycosylation are scarce. Here, protein glycosylation of exosomes from ovarian carcinoma SKOV3 cells has been studied by lectin blotting, NP-HPLC analysis of 2-aminobenzamide labeled glycans and mass spectrometry. An abundant sialoglycoprotein was found enriched in exosomes and it was identified by peptide mass fingerprinting and immunoblot as the galectin-3-binding protein (LGALS3BP). Exosomes were found to contain predominantly complex glycans of the di-, tri-, and tetraantennary type with or without proximal fucose and also high mannose glycans. Diantennary glycans containing bisecting N-acetylglucosamine were also detected. This work provides detailed information about glycoprotein and N-glycan composition of exosomes from ovarian cancer cells, furthermore it opens novel perspectives to further explore the functional role of glycans in the biology of exosomes.
    PLoS ONE 10/2013; 8(10):e78631. DOI:10.1371/journal.pone.0078631 · 3.23 Impact Factor
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