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Cited by 52Glycosylation and Glycoproteins ResearchAlzheimer's disease research and treatmentsCarbohydrate Chemistry and Synthesis

O-glycosylation on cerebrospinal fluid and plasma apolipoprotein E differs in the lipid-binding domain

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Flowers, Sarah A, Grant, Oliver C, Woods, Robert J, Rebeck, G William·2020·Glycobiology
DOI 10.1093/glycob/cwz084PMC PMC7335482
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Abstract

The O-glycoprotein apolipoprotein E (APOE), the strongest genetic risk factor for Alzheimer’s disease, associates with lipoproteins. Cerebrospinal fluid (CSF) APOE binds only high-density lipoproteins (HDLs), while plasma APOE attaches to lipoproteins of diverse sizes with binding fine-tuned by the C-terminal loop. To better understand the O-glycosylation on this critical molecule and differences across tissues, we analyzed the O-glycosylation on APOE isolated from the plasma and CSF of aged individuals. Detailed LC-MS/MS analyses allowed the identification of the glycosite and the attached glycan and site occupancy for all detectable glycosites on APOE and further three-dimensional modeling of physiological glycoforms of APOE. APOE is O-glycosylated at several sites: Thr8, Thr18, Thr194, Ser197, Thr289, Ser290 and Ser296. Plasma APOE held more abundant (20.5%) N-terminal (Thr8) sialylated core 1 (Neu5Acα2–3Galβ1–3GalNAcα1-) glycosylation compared to CSF APOE (0.1%). APOE was hinge domain glycosylated (Thr194 and Ser197) in both CSF (27.3%) and plasma (10.3%). CSF APOE held almost 10-fold more abundant C-terminal (Thr289, Ser290 and Ser296) glycosylation (36.8% of CSF peptide283–299 was glycosylated, 3.8% of plasma peptide283–299), with sialylated and disialylated (Neu5Acα2–3Galβ1–3(Neu5Acα2–6) GalNAcα1-) core 1 structures. Modeling suggested that C-terminal glycosylation, particularly the branched disialylated structure, could interact across domains including the receptor-binding domain. These data, although limited by sample size, suggest that there are tissue-specific APOE glycoforms. Sialylated glycans, previously shown to improve HDL binding, are more abundant on the lipid-binding domain of CSF APOE and reduced in plasma APOE. This indicates that APOE glycosylation may be implicated in lipoprotein-binding flexibility.

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  • Post-translational modifications present in cells but absent in recombinant protein may influence the structural consequences of the L28P mutation.

    “Second, post-translational modifications present in cells but absent in recombinant protein may influence the structural consequences of the L28P mutation 60,61 .”

    From Utilizing a cell culture based novel cellular thermal shift assay to understand the isoform-dependent thermal stability of ApoE variants (2026) · cites this paper as [60]

    The Discussion says O-glycosylation can affect protein structure and that APOE may be more heavily glycosylated inside cells than after secretion. It does not compare cellular APOE with recombinant protein or address the structural consequences of the L28P mutation. (LLM, conf=0.84)

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Cited by

Sorted by citations

Authors
Flowers, S. A., Grant, O. C., Woods, R. J., & Rebeck, G. W.
Affiliations
  • Georgetown University (US)
  • University of Georgia (US)
Corresponding author
Flowers, Sarah A
ORCID
Venue
Glycobiology
Publisher
Oxford University Press (OUP)
Published
2019-10-16
Volume
30
Issue
2
Pages
74-85
ISSN
  • 0959-6658 (ISSN-L)
  • 1460-2423
DOI
10.1093/glycob/cwz084
PMC
PMC7335482
OpenAlex
W2980885964
Cited by
52
References
7
Citations by year
2026: 7 · 2025: 5 · 2024: 5 · 2023: 7 · 2022: 14 · 2021: 6 · 2020: 8
FWCI
2.32
Type
journal article
Language
en
Open access
Licence
academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model (vor)
Locations
  • Glycobiology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Institutes of Health (R01 NS100714, U01 CA207824, P41 GM103390, R56 AG062305)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Glycosylation and Glycoproteins Research
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Physical Sciences › Chemistry › Organic Chemistry › Carbohydrate Chemistry and Synthesis
Keywords
O-glycosylation, cerebrospinal fluid, plasma, lipid-binding domain, C-terminal loop, hinge domain, Alzheimer's disease, high-density lipoprotein, glycoforms
MeSH terms
Protein Domains, Aged, Alzheimer Disease, Apolipoproteins E, Female, Glycopeptides, Glycosylation, Humans, Male, Middle Aged

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