Differential Signaling Mediated by ApoE2, ApoE3, and ApoE4 in Human Neurons Parallels Alzheimer's Disease Risk
Open accessPublished version of a preprint
Abstract
Abstract Apolipoprotein E (ApoE) mediates clearance of circulating lipoproteins from blood by binding to ApoE receptors. Humans express three genetic variants, ApoE2, ApoE3, and ApoE4, that exhibit distinct ApoE receptor binding properties. In brain, ApoE is abundantly produced by activated astrocytes and microglia, and three variants differentially affect Alzheimer’s disease (AD), such that ApoE2 protects against, and ApoE4 predisposes to the disease. A role for ApoE4 in driving microglial dysregulation and impeding Aβ clearance in AD is well documented, but the direct effects of three variants on neurons are poorly understood. Extending previous studies, we here demonstrate that ApoE variants differentially activate multiple neuronal signaling pathways and regulate synaptogenesis. Specifically, using human neurons cultured in the absence of glia to exclude indirect glial mechanisms, we show that ApoE broadly stimulates signal transduction cascades which among others enhance synapse formation with an ApoE4>ApoE3>ApoE2 potency rank order, paralleling the relative risk for AD conferred by these variants. Unlike the previously described induction of APP transcription, however, ApoE-induced synaptogenesis involves CREB rather than cFos activation. We thus propose that in brain, ApoE acts as a glia-secreted paracrine signal and activates neuronal signaling pathways in what may represent a protective response, with the differential potency of ApoE variants causing distinct levels of chronic signaling that may contribute to AD pathogenesis.
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
Binding to LDLR is required by ApoE to perform its downstream effector function.
“In line with this, binding to LDLR is required by ApoE to perform its downstream effector function (50–52).”
From Secreted Apoe rewires melanoma cell state vulnerability to ferroptosis (2024) · cites this paper as [52]
The Discussion says ApoE binding to receptors on neurons activates downstream signaling, and the Figure 9 legend reports that an ApoE-receptor blocker abolishes ApoE-induced increases in synaptic protein levels. These passages support a requirement for receptor binding in the neuronal effects studied, but do not establish that binding specifically to LDLR is required for ApoE’s downstream functions generally (page unavailable in our copy). (LLM, conf=0.85)
Experimental — accuracy not yet measuredMammalian expression systems retain physiologically relevant secretory, folding and post-translational modification mechanisms.
“Mammalian expression systems retain physiologically relevant secretory, folding and post-translational modification mechanisms, but column-purified recombinant ApoE is invariably prepared as apoprotein.22–25”
From ApoE is Secreted as a Lipid Nanoparticle by Mammalian Cells: Implications for Alzheimer’s Disease Pathogenesis (2025) · cites this paper as [25]
In “Physiologically produced lipidated ApoE reproducibly activates MAP-kinase signaling in human neurons” (page unavailable), the paper reports that HEK293-produced ApoE is secreted and has a glycosylation state, supporting the secretory and post-translational-modification parts of the claim. It also finds that HEK293-produced ApoE has signaling properties similar to physiologically produced ApoE. The copy does not establish that mammalian expression systems retain physiologically relevant folding mechanisms, or make that general claim about expression systems. (LLM, conf=0.84)
Experimental — accuracy not yet measuredTo date all reports describing the biochemical properties of this recombinant protein have deployed lipid-free biosynthetic materials.
“Although ApoE is not detected in appreciable quantities in its apo form in physiological fluids, to date all reports describing the biochemical properties of this recombinant protein have deployed lipid-free biosynthetic materials.21–25”
From ApoE is Secreted as a Lipid Nanoparticle by Mammalian Cells: Implications for Alzheimer’s Disease Pathogenesis (2025) · cites this paper as [25]
The Methods section (page unavailable) confirms that the paper used recombinant ApoE produced in HEK293 cells and bacteria, but it does not establish that those preparations were lipid-free. The section on physiologically produced lipidated ApoE (page unavailable) also reports testing ApoE-containing glial lipoproteins and LDL. This paper therefore does not support the claim that all such reports used lipid-free materials. (LLM, conf=0.83)
Experimental — accuracy not yet measuredColumn-purified recombinant ApoE is invariably prepared as apoprotein.
“Mammalian expression systems retain physiologically relevant secretory, folding and post-translational modification mechanisms, but column-purified recombinant ApoE is invariably prepared as apoprotein.22–25”
From ApoE is Secreted as a Lipid Nanoparticle by Mammalian Cells: Implications for Alzheimer’s Disease Pathogenesis (2025) · cites this paper as [25]
The 'Production of recombinant proteins' methods describe HEK293- and bacteria-produced ApoE but do not state that column-purified recombinant ApoE is an apoprotein. The 'Lipidated ApoE' methods describe purification of glial lipoproteins, a different preparation. Searches for apoprotein, lipid-free recombinant ApoE, and column purification found no passage establishing the claim. (LLM, conf=0.72)
Experimental — accuracy not yet measuredApoE is not detected in appreciable quantities in its apo form in physiological fluids.
“Although ApoE is not detected in appreciable quantities in its apo form in physiological fluids, to date all reports describing the biochemical properties of this recombinant protein have deployed lipid-free biosynthetic materials.21–25”
From ApoE is Secreted as a Lipid Nanoparticle by Mammalian Cells: Implications for Alzheimer’s Disease Pathogenesis (2025) · cites this paper as [25]
The Introduction describes ApoE as a major component of circulating lipoproteins, and the section on physiologically produced lipidated ApoE finds it in human-plasma LDL (page numbers unavailable). Neither passage establishes that appreciable quantities of lipid-free ApoE are absent from physiological fluids. Searches for apo-form and lipid-free ApoE did not find that claim in our copy. (LLM, conf=0.72)
Experimental — accuracy not yet measured
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Cites
Molecular Architecture of the Mouse Nervous System
Zeisel, A., Hochgerner, H., Lönnerberg, P., Johnsson, A., Memic, F., van der Zwan, J., Häring, M., Braun, E., Borm, L. E., La Manno, G., et al. (2018) · Cell · doi:10.1016/j.cell.2018.06.021 · Cited by 2,995 · see citing works
Krasemann, S., Madore, C., Cialic, R., Baufeld, C., Calcagno, N., El Fatimy, R., Beckers, L., O’Loughlin, E., Xu, Y., Fanek, Z., et al. (2017) · Immunity · doi:10.1016/j.immuni.2017.08.008 · Cited by 2,979 · see citing works
Molecular diversity and specializations among the cells of the adult mouse brain
Saunders, A., Macosko, E. Z., Wysoker, A., Goldman, M., Krienen, F. M., de Rivera, H., Bien, E., Baum, M., Bortolin, L., Wang, S., et al. (2018) · Cell · doi:10.1016/j.cell.2018.07.028 · Cited by 1,847 · see citing works
A Century of Cholesterol and Coronaries: From Plaques to Genes to Statins
Goldstein, J. L., & Brown, M. S. (2015) · Cell · doi:10.1016/j.cell.2015.01.036 · Cited by 1,233 · see citing works
Human ApoE isoforms differentially regulate brain amyloid-β peptide clearance
Castellano, J. M., Kim, J., Stewart, F. R., Jiang, H., DeMattos, R. B., Patterson, B. W., Fagan, A. M., Morris, J. C., Mawuenyega, K. G., Cruchaga, C., et al. (2011) · Science Translational Medicine · doi:10.1126/scitranslmed.3002156 · Cited by 1,227 · see citing works
Apolipoprotein E: Structure-Function Relationships
Weisgraber, K. H. (1994) · Advances in Protein Chemistry · doi:10.1016/s0065-3233(08)60642-7 · Cited by 830 · see citing works
apoE isoform–specific disruption of amyloid β peptide clearance from mouse brain
Deane, R., Sagare, A., Hamm, K., Parisi, M., Lane, S., Finn, M. B., Holtzman, D. M., & Zlokovic, B. V. (2008) · Journal of Clinical Investigation · doi:10.1172/jci36663 · Cited by 771 · see citing works
Wang, C., Najm, R., Xu, Q., Jeong, D.-E., Walker, D., Balestra, M. E., Yoon, S. Y., Yuan, H., Li, G., Miller, Z. A., et al. (2018) · Nature Medicine · doi:10.1038/s41591-018-0004-z · Cited by 428 · see citing works
Self-citationThe Triggering Receptor Expressed on Myeloid Cells 2 Binds Apolipoprotein E
Bailey, C. C., DeVaux, L. B., & Farzan, M. (2015) · Journal of Biological Chemistry · doi:10.1074/jbc.m115.677286 · Cited by 303 · see citing works
Sebastiano, V., Zhen, H. H., Haddad, B., Bashkirova, E., Melo, S. P., Wang, P., Leung, T. L., Siprashvili, Z., Tichy, A., Li, J., et al. (2014) · Science Translational Medicine · doi:10.1126/scitranslmed.3009540 · Cited by 213 · see citing works
Self-citationDeMattos, R. B., Brendza, R. P., Heuser, J. E., Kierson, M., Cirrito, J. R., Fryer, J., Sullivan, P. M., Fagan, A. M., Han, X., & Holtzman, D. M. (2001) · Neurochemistry International · doi:10.1016/s0197-0186(01)00049-3 · Cited by 180 · see citing works
Hu, J., Liu, C.-C., Chen, X.-F., Zhang, Y.-W., Xu, H., & Bu, G. (2015) · Molecular Neurodegeneration · doi:10.1186/s13024-015-0001-3 · Cited by 161 · see citing works
ApoE, ApoE Receptors, and the Synapse in Alzheimer's Disease
Lane-Donovan, C., & Herz, J. (2017) · Trends in Endocrinology & Metabolism · doi:10.1016/j.tem.2016.12.001 · Cited by 157 · see citing works
Mak, A. C. Y., Pullinger, C. R., Tang, L. F., Wong, J. S., Deo, R. C., Schwarz, J.-M., Gugliucci, A., Movsesyan, I., Ishida, B. Y., Chu, C., et al. (2014) · JAMA Neurology · doi:10.1001/jamaneurol.2014.2011 · Cited by 96 · see citing works
Apolipoprotein E and Alzheimer's disease: the protective effects of ApoE2 and E3
Rebeck, G. W., Kindy, M., & LaDu, M. J. (2002) · Journal of Alzheimer's Disease · doi:10.3233/jad-2002-4304 · Cited by 89 · see citing works
Apolipoprotein E Genotype Affects Size of ApoE Complexes in Cerebrospinal Fluid
Heinsinger, N. M., Gachechiladze, M. A., & Rebeck, G. W. (2016) · Journal of Neuropathology & Experimental Neurology · doi:10.1093/jnen/nlw067 · Cited by 74 · see citing works
Flagged first, then by citations
Research works printed but not linked: 4
- Masliah E, Mallory M, Alford M, Ge N, and Mucke L (1995) Abnormal synaptic regeneration in hAPP695 transgenic and ApoE knockout mice. In: Research advances in Alzheimer's disease and related disorders (Igbal K, Mortimer JA, Winblad B, Wisniewski HM, eds), pp 405-414. New York: Wiley.
- Schmidt V, Carlo AS, Willnow TE (2014) Apolipoprotein E receptor path- ways in Alzheimer disease. Wiley Interdiscip Rev Syst Biol Med 6:255- 270.
- Strittmatter WJ, Saunders AM, Schmechel D, Pericak-Vance M, Enghild J, Salvesen GS, Roses AD (1993) Apolipoprotein E: high-avidity binding to beta-amyloid and increased frequency of type 4 allele in late-onset familial Alzheimer disease. Proc Natl Acad Sci U S A 90:1977-1981.
- Utermann G (1985) Morgagni lecture: genetic polymorphism of apolipo- protein E: Impact on plasma lipoprotein metabolism. In: Diabetes, obe- sity and hyperlipidemias (Crepaldi G, Tiengo A, Baggio G, eds.), pp 1-28. Amsterdam: Elsevier.
Cited by
Sorted by citations
The cell biology of synapse formation
Südhof, T. C. (2021) · Journal of Cell Biology · doi:10.1083/jcb.202103052 · Cited by 358 · see citing works
Self-citationAn optimized quantitative proteomics method establishes the cell type‐resolved mouse brain secretome
Tüshaus, J., Müller, S. A., Kataka, E. S., Zaucha, J., Sebastian Monasor, L., Su, M., Güner, G., Jocher, G., Tahirovic, S., Frishman, D., et al. (2020) · The EMBO Journal · doi:10.15252/embj.2020105693 · Cited by 88 · see citing works
Huang, S., Zhang, Z., Cao, J., Yu, Y., & Pei, G. (2022) · Signal Transduction and Targeted Therapy · doi:10.1038/s41392-022-01006-x · Cited by 72 · see citing works
Effects of APOE4 allelic dosage on lipidomic signatures in the entorhinal cortex of aged mice
Miranda, A. M., Ashok, A., Chan, R. B., Zhou, B., Xu, Y., McIntire, L. B., Area-Gomez, E., Di Paolo, G., Duff, K. E., Oliveira, T. G., et al. (2022) · Translational Psychiatry · doi:10.1038/s41398-022-01881-6 · Cited by 60 · see citing works
“, downstream of neuronal receptor signaling) [80].”
Self-citationAyton, S., & Bush, A. I. (2021) · Ageing Research Reviews · doi:10.1016/j.arr.2020.101212 · Cited by 45 · see citing works
The role of genetic risk factors of Alzheimer’s disease in synaptic dysfunction
Fu, W.-Y., & Ip, N. Y. (2023) · Seminars in Cell & Developmental Biology · doi:10.1016/j.semcdb.2022.07.011 · Cited by 48 · see citing works
Secreted Apoe rewires melanoma cell state vulnerability to ferroptosis
More, S., Bonnereau, J., Wouters, D., Spotbeen, X., Karras, P., Rizzollo, F., Killian, T., Venken, T., Naulaerts, S., Vervoort, E., et al. (2024) · Science Advances · doi:10.1126/sciadv.adp6164 · Cited by 25 · see citing works
Hernandez Arriaza, R., Reil, D., Fatuzzo, N., Fu, M., Dai, Y., Fernandez Martinez, D., Jiang, H., Holtzman, D. M., Greicius, M. D., & Khosla, C. (2025) · Biochemistry · doi:10.1021/acs.biochem.5c00503 · Cited by 2 · see citing works
Frisch, C., Baker, L., Srinivasan, G., Mintah, A. E., Leyasi, S., Pedroza, M., Galyon, B., & Brafman, D. A. (2026) · Frontiers in Aging Neuroscience · doi:10.3389/fnagi.2026.1856154
- Authors
- Huang, Y.-W. A., Zhou, B., Nabet, A. M., Wernig, M., & Südhof, T. C.
- Affiliations
- Howard Hughes Medical Institute (US)
- Stanford Medicine (US)
- Corresponding author
- Huang, Yu-Wen Alvin
- Südhof, Thomas C.
- Venue
- The Journal of Neuroscience
- Publisher
- Society for Neuroscience
- Published
- 2019-07-22
- Volume
- 39
- Issue
- 37
- Pages
- 7408-7427
- ISSN
- 0270-6474 (ISSN-L)
- 1529-2401
- PMC
- PMC6759032
- OpenAlex
- W2962887615
- Cited by
- 152
- References
- 16
- Citations by year
- 2026: 17 · 2025: 19 · 2024: 27 · 2023: 22 · 2022: 25 · 2021: 22 · 2020: 18 · 2019: 2
- FWCI
- 11.49
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Neuroscience (publishedVersion)
- bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Howard Hughes Medical Institute
- National Institutes of Health (AG04813101, K99-R00)
- National Institute on Aging (K99AG054616, R00AG054616, RF1AG048131)
- Topics
- Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
- Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
- Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
- Keywords
- apolipoprotein E, APOE2, APOE3, APOE ε4, Alzheimer's disease risk, human neurons, synaptogenesis, APP expression, CREB activation, c-fos, neuronal signaling pathways, embryonic stem cell-derived neurons, apoE receptors, amyloid-beta clearance, astrocytes
- MeSH terms
- Alzheimer Disease, Animals, Animals, Newborn, Cells, Cultured, Double-Blind Method, Female, Humans, Male, Neurons, Random Allocation, Genetic Variation, Signal Transduction, Genetic Predisposition to Disease, Mice, Apolipoprotein E3, Apolipoprotein E4, Apolipoprotein E2, Embryonic Stem Cells, HEK293 Cells
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
