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Cited by 259Alzheimer's disease research and treatmentsDementia and Cognitive Impairment ResearchNeuroinflammation and Neurodegeneration Mechanisms

APOE4-specific Changes in Aβ Accumulation in a New Transgenic Mouse Model of Alzheimer Disease

Open access
Youmans, Katherine L., Tai, Leon M., Nwabuisi-Heath, Evelyn, Jungbauer, Lisa, Kanekiyo, Takahisa, Gan, Ming, Kim, Jungsu, Eimer, William A. +6 more·2012·Journal of Biological Chemistry
DOI 10.1074/jbc.m112.407957PMC PMC3516726
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Abstract

APOE4 is the greatest risk factor for Alzheimer disease (AD) and synergistic effects with amyloid-β peptide (Aβ) suggest interactions among apoE isoforms and different forms of Aβ accumulation. However, it remains unclear how the APOE genotype affects plaque morphology, intraneuronal Aβ, soluble Aβ42, and oligomeric Aβ (oAβ), particularly in vivo. As the introduction of human APOE significantly delays amyloid deposition in transgenic mice expressing familial AD (FAD) mutations (FAD-Tg), 5xFAD-Tg mice, which exhibit amyloid deposition by age 2 months, were crossed with apoE-targeted replacement mice to produce the new EFAD-Tg mice. Compared with 5xFAD mice, Aβ deposition was delayed by ∼4 months in the EFAD mice, allowing detection of early changes in Aβ accumulation from 2-6 months. Although plaque deposition is generally greater in E4FAD mice, E2/E3FAD mice have significantly more diffuse and E4FAD more compact plaques. As a first report in FAD-Tg mice, the APOE genotypes had no effect on intraneuronal Aβ accumulation in EFAD mice. In E4FAD mice, total apoE levels were lower and total Aβ levels higher than in E2FAD and E3FAD mice. Profiles from sequential three-step extractions (TBS, detergent, and formic acid) demonstrated that the lower level of total apoE4 is reflected only in the detergent-soluble fraction, indicating that less apoE4 is lipoprotein-associated, and perhaps less lipidated, compared with apoE2 and apoE3. Soluble Aβ42 and oAβ levels were highest in E4FAD mice, although soluble apoE2, apoE3, and apoE4 levels were comparable, suggesting that the differences in soluble Aβ42 and oAβ result from functional differences among the apoE isoforms. Thus, APOE differentially regulates multiple aspects of Aβ accumulation.

AI snapshot

Written from the paper’s full text.

TL;DR

A new EFAD mouse model (5xFAD crossed with human APOE-targeted replacement mice) delays Aβ deposition by ~4 months versus 5xFAD, creating a 2–6-month window to compare APOE genotypes. APOE4 uniquely increases compact plaques, total/soluble Aβ42, and oligomeric Aβ, while total apoE4 is lower and less lipoprotein-associated, but intraneuronal Aβ is comparable across APOE genotypes.

Key findings

  • Aβ deposition was delayed ~4 months in EFAD versus 5xFAD mice; plaque deposition was generally greatest in E4FAD, significant at 4 months in frontal cortex and subiculum and at 6 months in frontal cortex. At 6 months in subiculum, E2FAD and E4FAD plaque levels were both significantly higher than E3FAD.
  • Plaque morphology differed by APOE genotype: E2FAD and E3FAD had mostly diffuse plaques (>50%), whereas diffuse plaques were significantly lower in E4FAD (~30% at 6 months); compact plaques were ~20% in E2FAD/E3FAD but 40–50% in E4FAD.
  • Intraneuronal Aβ increased with age and varied by brain region but showed no significant APOE genotype-specific differences in frontal cortex, subiculum, or CA3.
  • Total apoE4 was lower than apoE2/apoE3, reflected only in the TBSX detergent-soluble fraction, suggesting less apoE4 is lipoprotein-associated. Total Aβ42 was higher in E4FAD; soluble Aβ42 was 2-fold higher in cortex and 3-fold higher in hippocampus, and oligomeric Aβ was ~2-fold higher in cortex and 3-fold higher in hippocampus in E4FAD versus E2FAD/E3FAD. At 6 months, TBS-soluble and FA-extracted Aβ42 in E4FAD were at least 4-fold higher than in E2FAD or E3FAD.

Methods

  • EFAD mice were generated by crossing 5xFAD mice carrying five FAD mutations with homozygous human APOE2-, APOE3-, or APOE4-targeted replacement mice; male mice were used at 2, 4, and 6 months.
  • Brains were analyzed by immunohistochemistry with MOAB-2 and NeuN, Thioflavin S plaque staining and morphology quantification, unbiased stereology for intraneuronal Aβ, three-step sequential extraction (TBS, TBSX, formic acid), and ELISAs for apoE, Aβ42, and oligomeric Aβ; APP levels were checked by Western blot.
  • Data were analyzed by one-way or two-way ANOVA with Tukey’s or Bonferroni’s post hoc tests; p < 0.05 was considered significant.

Limitations

  • The paper states that female mice were excluded from this initial study for consistency because apoE isoform-specific interactions with Aβ are known to be influenced by gender.
  • The paper notes that the 2–6-month window is still early in the overall process of Aβ accumulation and that drug intervention trials have not yet been performed in EFAD mice.
  • Evident from the text: the study is limited to male mice, does not report cognitive/behavioral outcomes, and focuses on correlative biochemical and histological changes rather than establishing causal mechanisms.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1074/jbc.m112.407957

Cites

95 of 95 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

28 of 38 cited sources checked · 19 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    5xFAD mice exhibit accelerated plaque deposition that is significant by 2 months.

    “transgenic mice expressing five FAD mutations (5xFAD), which exhibit accelerated plaque deposition that is significant by 2 months (11)”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [11] Oakley, 2006, Intraneuronal β-amyloid aggregates, neurodegeneration, and neuron loss in transgenic mice with five familial Alzheimer's disease mutations: potential factors in amyloid plaque formation, J. Neurosci. source

      The section “5XFAD mice rapidly accumulate massive Aβ42 levels in brain” reports plaque deposition starting at 2 months in line Tg6799, but not in all 5XFAD lines: deposition began at 4 and 6 months in the other two lines. The claim omits that qualification, and the passage does not report a statistical significance test for plaque deposition at 2 months. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Premisecitation

    Plaque deposition is increased with APOE4 compared with APOE2 and APOE3 in humans and transgenic mice expressing familial AD mutations.

    “Plaque deposition is increased with APOE4 compared with APOE2 and APOE3 in humans and transgenic mice expressing familial AD (FAD) mutations (FAD-Tg) (2)(3)(4)(5).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [2] Kim, 2011, Haploinsufficiency of human APOE reduces amyloid deposition in a mouse model of amyloid-β amyloidosis, J. Neurosci. source

      The Discussion (page unavailable) reports APOE-dependent amyloid deposition in humans and Aβ-depositing mouse models, and specifically greater deposition with APOE4 than APOE3 in the APPPS1-21 mouse model. The Results also confirm greater plaque deposition with APOE4 than APOE3 in those mice. The paper does not report an APOE4-versus-APOE2 plaque-deposition comparison; its E4>E3>E2 ordering concerns a possible effect on Aβ clearance. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [3] Bales, 2009, Human APOE isoform-dependent effects on brain β-amyloid levels in PDAPP transgenic mice, J. Neurosci. source
    • cites [4] Drzezga, 2009, Effect of APOE genotype on amyloid plaque load and gray matter volume in Alzheimer disease, Neurology source
  • Premisecitation

    The human study measured Aβ40.

    “However, this human study measured A␤40”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [63] Christensen, 2010, Accumulation of intraneuronal Aβ correlates with ApoE4 genotype, Acta Neuropathol. source
  • Premisecitation

    MOAB-2 demonstrates strong intraneuronal immunoreactivity in 5xFAD and 3xTg mouse brain tissue that precedes extracellular Aβ deposition.

    “MOAB-2 demonstrates strong intraneuronal immunoreactivity in 5xFAD and 3xTg mouse brain tissue that precedes extracellular A␤ deposition.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [25] Youmans, 2012, Intraneuronal Aβ detection in 5xFAD mice by a new Aβ-specific antibody, Mol. Neurodegener. source
  • Premisecitation

    oAβ-induced deficits in neuronal viability are enhanced in the presence of APOE4 compared with APOE2 and APOE3.

    “oA␤-induced deficits in synaptic plasticity (78) and neuronal viability (79) are enhanced in the presence of APOE4 compared with APOE2 and APOE3.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [79] Manelli, 2007, Aβ42 neurotoxicity in primary co-cultures: effect of apoE isoform and Aβ conformation, Neurobiol. Aging source
  • May combine two claims. 34
  • Classified as probably not a substantial claim. 18

  • May combine two claims.

    Premisecitation

    Introduction of human APOE to existing FAD-Tg mice significantly delays plaque deposition, although once detected, plaque levels are generally greater with APOE4 than APOE3.

    “Introduction of human APOE to existing FAD-Tg mice significantly delays plaque deposition, although once detected, plaque levels are generally greater with APOE4 than APOE3 (3, 6 -8).”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites [3] Bales, 2009, Human APOE isoform-dependent effects on brain β-amyloid levels in PDAPP transgenic mice, J. Neurosci. source
    • cites [6] Buttini, 2002, Modulation of Alzheimer-like synaptic and cholinergic deficits in transgenic mice by human apolipoprotein E depends on isoform, aging, and overexpression of amyloid β peptides but not on plaque formation, J. Neurosci. source

      In the Results section on plaque formation (page unavailable), plaques were absent at 6–15 months in mice with or without human apoE, while 19–24-month-old hAPP/apoE4 mice had more plaques than hAPP/apoE3 mice. The paper supports the APOE4-versus-APOE3 comparison, but it does not show that introducing human APOE significantly delayed plaque deposition relative to hAPP mice lacking apoE. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [7] Holtzman, 2000, Apolipoprotein E isoform-dependent amyloid deposition and neuritic degeneration in a mouse model of Alzheimer's disease, Proc. Natl. Acad. Sci. U.S.A. source

  • May combine two claims.

    Interpretationown data

    APOE2-induced deposition of diffuse plaques is novel in a mouse model and consistent with previous work by Dr. C. Kawas and co-workers.

    “This APOE2induced deposition of diffuse plaques is novel in a mouse model and consistent with the previous work by Dr. C. Kawas and co-workers (54,55) who report that increased diffuse plaques are associated with APOE2 in cognitively normal subjects compared with compact plaques in APOE4 AD patients from the oldest of the old study.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [54] Berlau, 2009, APOE ϵ2 is associated with intact cognition but increased Alzheimer pathology in the oldest old, Neurology source

      The Results (page unavailable) report a trend toward more diffuse plaques in oldest-old APOE2 carriers versus APOE3/3 carriers, and greater plaque pathology in non-demented APOE2 carriers. They do not establish increased diffuse plaques specifically in cognitively normal APOE2 subjects or the claimed contrast with compact plaques in APOE4 Alzheimer’s patients. The mouse-model novelty is the citing authors’ own finding, not a claim attributed to this source. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [55] Berlau, 2007, Dissociation of neuropathologic findings and cognition: case report of an apolipoprotein E ϵ2/ϵ2 genotype, Arch. Neurol. source

  • May combine two claims.

    Study design and conductcitation

    The MOAB-2-based oAβ42 ELISA detects oligomeric but not monomeric Aβ42.

    “In addition, the MOAB-2-based oA␤42 ELISA detects oligomeric but not monomeric A␤42 using synthetic preparations characterized previously by our laboratory (data not shown) (47,48).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [47] Dahlgren, 2002, Oligomeric and fibrillar species of amyloid-β peptides differentially affect neuronal viability, J. Biol. Chem. source
    • cites [48] Stine, 2003, In vitro characterization of conditions for amyloid-β peptide oligomerization and fibrillogenesis, J. Biol. Chem. source

  • May combine two claims.

    Study design and conductcitation

    Female mice were excluded from this initial study for consistency, as apoE isoform-specific interaction with Aβ are known to be influenced by gender.

    “Female mice were excluded from this initial study for consistency, as apoE isoform-specific interaction with A␤ are known to be influenced by gender (for review (44)).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [44] Tai, 2011, Introducing human APOE into Aβ transgenic mouse models, Int. J. Alzheimers Dis. source

      Sections 2.3 and 2.4 report that apoE isoform-related cognitive effects differ between female and male mice, supporting the general concern about sex differences. Sections 3.3 and 3.5 discuss isoform-specific Aβ pathology but do not establish that the apoE–Aβ interaction itself differs by sex. The paper also does not address the citing study’s decision to exclude female mice. (LLM, conf=0.82)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Bexarotene increases apoE levels in mice within hours.

    “bexarotene (an RXR agonist) increases apoE levels”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [76] Cramer, 2012, ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models, Science source

      The apoE-expression passage (indexed under Abstract; page not provided) reports increased apoE expression in bexarotene-treated mice after treatment measured in days. The six-hour passage reports a decrease in Aβ, not an increase in apoE, so the added 'within hours' timing is not supported. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    oAβ species accumulate at the periphery of dense-cored plaques and compact plaques enhance Aβ toxicity indirectly by creating a platform on which toxic oAβ species can accumulate or stabilize.

    “A renewed interest in the pathological role of plaques has suggested that oA␤ species accumulate at the periphery of densecored plaques (60,61) and that compact plaques enhance A␤ toxicity indirectly by creating a platform on which toxic oA␤ species can accumulate or stabilize.”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [60] Koffie, 2009, Oligomeric amyloid β associates with postsynaptic densities and correlates with excitatory synapse loss near senile plaques, Proc. Natl. Acad. Sci. U.S.A. source
    • cites [61] Spires-Jones, 2011, Monitoring protein aggregation and toxicity in Alzheimer's disease mouse models using in vivo imaging, Methods source

      The Discussion (page unavailable) links plaques to nearby neuronal damage and identifies soluble Aβ as a possible mediator. It does not say that oligomeric Aβ accumulates at the periphery of dense-cored plaques or that compact plaques provide a platform that stabilizes it. Searches for oligomers at plaque edges and for the proposed platform mechanism found no passage addressing those points. (LLM, conf=0.70)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Bexarotene significantly reduces insoluble Aβ after 3 days.

    “significantly reduces insoluble A␤ after 3 days”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [76] Cramer, 2012, ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models, Science source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A single human study reports an increase in intraneuronal Aβ with one or two alleles of APOE4.

    “These data are in apparent contrast with data from a single study in humans that reports an increase in intraneuronal A␤ with one or two alleles of APOE4 (63).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [63] Christensen, 2010, Accumulation of intraneuronal Aβ correlates with ApoE4 genotype, Acta Neuropathol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Soluble oligomers correlate with cognitive decline (MMSE scores) and tangle stage.

    “soluble oligomers correlate with cognitive decline (Mini Mental State Examination (MMSE) scores) and tangle stage (20).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [20] Tomic, 2009, Soluble fibrillar oligomer levels are elevated in Alzheimer's disease brain and correlate with cognitive dysfunction, Neurobiol. Dis. source

  • May combine two claims.

    Premisecitation

    APOE4 carriers can exhibit a differential response to certain therapeutic interventions, complicating the interpretation of drug trials.

    “APOE4 carriers can exhibit a differential response to certain therapeutic interventions, complicating the interpretation of drug trials”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [53] Verghese, 2011, Apolipoprotein E in Alzheimer's disease and other neurological disorders, Lancet Neurol. source

  • Classified as probably not a substantial claim.

    Premisecitation

    Bexarotene decreases soluble Aβ in mice within hours.

    “decreases soluble A␤ in mice within hours”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [76] Cramer, 2012, ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models, Science source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In FAD-Tg mice, soluble oAβ suppresses synaptic function.

    “In FAD-Tg mice, soluble oA␤ suppresses synaptic function”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [52] Larson, 2012, Soluble Aβ oligomer production and toxicity, J. Neurochem. source

      In ‘II. Toxicity of Oligomeric Aβ Assemblies’ (page unavailable), the review reports that soluble Aβ oligomers inhibit LTP, a measure of synaptic plasticity. It also describes Aβ-induced neuronal and cognitive deficits in APP-transgenic mice, but does not clearly establish that soluble oligomers suppress synaptic function specifically in those mice. (LLM, conf=0.80)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In FAD-Tg mice, soluble oAβ impairs learning and memory.

    “impairs learning and memory (52).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [52] Larson, 2012, Soluble Aβ oligomer production and toxicity, J. Neurochem. source

  • Classified as probably not a substantial claim.

    Premisecitation

    Intraneuronal Aβ accumulation may be an important proximal neurotoxic event in AD pathogenesis.

    “recent evidence indicates that intraneuronal A␤ accumulation may be an important proximal neurotoxic event in AD pathogenesis (for review see Ref. 56,57).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [56] Gouras, 2010, Intraneuronal β-amyloid accumulation and synapse pathology in Alzheimer's disease, Acta Neuropathol. source
    • cites [57] Bayer, 2010, Intracellular accumulation of amyloid-β: a predictor for synaptic dysfunction and neuron loss in Alzheimer's disease, Front. Aging Neurosci. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In FAD-Tg mice, soluble oAβ reduces synaptic plasticity.

    “reduces synaptic plasticity”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [52] Larson, 2012, Soluble Aβ oligomer production and toxicity, J. Neurochem. source

      The Toxicity of Oligomeric Aβ Assemblies section (page unavailable) says oligomeric Aβ can impair synaptic plasticity. It also discusses Aβ oligomers and deficits in transgenic mouse models, but the passages do not establish that soluble oligomers reduced synaptic plasticity specifically in those mice; the mouse-model findings described concern cognition or neuronal function. (LLM, conf=0.82)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Plaque levels at 3 months remained unchanged after bexarotene.

    “although plaque levels at 3 months remained unchanged (76).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [76] Cramer, 2012, ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models, Science source

  • May combine two claims.

    Study design and conductcitation

    MOAB-2 is a high-affinity antibody specific for Aβ that does not detect APP.

    “MOAB-2 was developed in the LaDu laboratory and is a high-affinity antibody specific for A␤ that does not detect APP.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [25] Youmans, 2012, Intraneuronal Aβ detection in 5xFAD mice by a new Aβ-specific antibody, Mol. Neurodegener. source

  • May combine two claims.

    Findingown data

    In E4FAD mice, oAβ levels were approximately 2-fold higher in the cortex and 3-fold higher in the hippocampus compared with those in E2FAD and E3FAD mice.

    “In E4FAD mice, oA␤ levels were ϳ2-fold higher in the cortex and 3-fold higher in the hippocampus compared with those in E2FAD and E3FAD mice.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Aβ42 levels were lowest in the cerebellum, higher in the cortex, and highest in the hippocampus.

    “As observed for apoE, A␤42 levels were lowest in the cerebellum, higher in the cortex, and highest in the hippocampus (Fig. 4B, p Ͻ 0.001; note the y axis values change for the cerebellum and cortex versus the hippocampus).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Aβ accumulation appears earlier and is greater in the subiculum compared with the frontal cortex.

    “A␤ accumulation appeared earlier and was greater in the subiculum compared with the frontal cortex, allowing for regional, as well as temporal, comparisons of the effects of the APOE genotype on the progression of A␤ accumulation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    ApoE4 levels are significantly lower than apoE2 and apoE3 in the cerebellum at 4 months, in the cortex at 2, 4, and 6 months, and in the hippocampus at 2 and 4 months.

    “Specifically, apoE4 levels are significantly lower than apoE2 and apoE3 in the cerebellum at 4 months, in the cortex at 2, 4, and 6 months, and in the hippocampus at 2 and 4 months of age (for specific comparisons, see Fig. 4A).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Total apoE levels in EFAD mice are lowest in the cerebellum, significantly higher in the cortex, and highest in the hippocampus.

    “Interestingly, total apoE levels in the EFAD mice were lowest in the cerebellum, significantly higher in the cortex, and highest in the hippocampus (Fig. 4A, dashed lines mean the data are collapsed by genotype and age within a region; p Ͻ 0.001).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The majority of plaques in EFAD mice are either diffuse or compact, and this distribution does not change with age.

    “The majority of the plaques in EFAD mice were either diffuse or compact, and this distribution in plaque morphology did not change with age (Fig. 2E).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    ApoE levels did not change in response to age, and there was no APOE genotype-specific response to increasing Aβ accumulation.

    “In addition, apoE levels did not change in response to age, and thus there was no APOE genotype-specific response to increasing A␤ accumulation (Fig. 4B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    FA-extracted Aβ42 levels increased with age for all APOE genotypes and were significantly higher in E4FAD mice at 4 and 6 months compared with E2FAD and E3FAD mice.

    “FA-extracted A␤42 levels increased with age for all APOE genotypes and were significantly higher in E4FAD mice at 4 and 6 months compared with E2FAD and E3FAD mice (Fig. 5B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Approximately 20% of plaques in E2FAD and E3FAD mice are compact, whereas 40-50% of plaques in E4FAD mice are compact.

    “The reverse pattern was observed with compact plaques; ϳ20% of the plaques in E2FAD and E3FAD mice were compact, whereas 40 -50% of plaques in E4FAD mice were compact.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the cortex, Aβ42 levels were generally low at 2 months but increased significantly by 4 months such that E4FAD > E3FAD = E2FAD.

    “In the cortex, A␤42 levels were generally low at 2 months but increased significantly by 4 months such that E4FAD Ͼ E3FAD ϭ E2FAD.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the hippocampus, Aβ42 levels were low at 2 months but increased significantly by 4 and 6 months such that E4FAD > E3FAD = E2FAD.

    “In the hippocampus, A␤42 levels were low at 2 months but increased significantly by 4 and 6 months such that E4FAD Ͼ E3FAD ϭ E2FAD.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    ApoE2 and apoE3 were extracted primarily to the TBSX fraction, whereas apoE4 levels were significantly lower in this fraction at 2, 4, and 6 months.

    “ApoE2 and apoE3 were extracted primarily to the TBSX fraction, whereas apoE4 levels were significantly lower in this fraction at 2, 4, and 6 months.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Soluble apoE levels were comparable in the cortex and hippocampus and did not vary significantly by APOE genotype.

    “Soluble apoE levels were comparable in the cortex (Fig. 6A) and hippocampus (Fig. 6B) and did not vary significantly by APOE genotype.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Aβ accumulation is earliest in E4FAD mice, followed by E3FAD and E2FAD mice, which are equivalent.

    “Compared with 5xFAD mice, A␤ deposition was delayed ϳ4 months in the EFAD mice, with accumulation earliest in E4FAD Ͼ E3FAD ϭ E2FAD.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In E2FAD and E3FAD mice, the majority of plaques are diffuse, accounting for more than 50% of total plaques, whereas diffuse plaques are significantly lower in E4FAD mice (e.g. 30% at 6 months).

    “In E2FAD and E3FAD mice the majority of plaques were diffuse, accounting for more than 50% of total plaques, whereas diffuse plaques were significantly lower in E4FAD mice (e.g.30% at 6 months).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    From 4 to 6 months, the proportion of diffuse plaques decreased and that of compact plaques increased only in E4FAD mice.

    “In addition, from 4 to 6 months, the proportion of diffuse plaques decreased and that of compact plaques increased only in the E4FAD mice (Fig. 2E).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In both the cortex and the hippocampus, soluble Aβ42 levels were 2-fold and 3-fold higher, respectively, in E4FAD mice compared with E2FAD and E3FAD mice.

    “Further, in both the cortex and the hippocampus, soluble A␤42 levels were 2-fold and 3-fold higher, respectively, in E4FAD mice compared with E2FAD and E3FAD mice.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Analysis of plaque morphology revealed that whereas the majority of the APOE4 plaques are compact, the majority of the APOE2 plaques are diffuse.

    “However, analysis of plaque morphology revealed that whereas the majority of the APOE4 plaques are compact, the majority of the APOE2 plaques are diffuse.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Findingnone given

    EFAD mice express almost exclusively Aβ42.

    “whereas the EFAD mice express almost exclusively A␤42”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The apoE4-specific distribution appears to occur in the hippocampus and cortex, which are AD-susceptible brain regions, and not the cerebellum, a disease-resistant region.

    “Further, this apoE4-specific distribution appears to occur in the hippocampus and cortex, which are AD-susceptible brain regions, and not the cerebellum, a disease-resistant region.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Compared with 5xFAD mice, Aβ deposition was delayed by ~4 months in the EFAD mice, allowing detection of early changes in Aβ accumulation from 2-6 months.

    “Compared with 5xFAD mice, A␤ deposition was delayed by ϳ4 months in the EFAD mice, allowing detection of early changes in A␤ accumulation from 2-6 months.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    In EFAD mice, Aβ deposition is delayed approximately 4 months compared with 5xFAD mice, creating a window from 2 to 6 months during which comparisons of multiple forms of Aβ accumulation can be measured.

    “In EFAD mice, A␤ deposition is delayed ϳ4 months compared with 5xFAD mice, creating a window from 2 to 6 months during which comparisons of multiple forms of A␤ accumulation can be measured, although this is still early in the overall process of A␤ accumulation in either the hippocampus or the cortex.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Crossing apoE-targeted replacement mice with PDAPP mice delays plaque deposition from approximately 10 to 18 months, although once detected, plaque levels are greater with APOE4 than APOE3.

    “For example, crossing apoE-targeted replacement mice (apoE-TR) (9) with PDAPP mice (10) delays plaque deposition from ϳ10 to 18 months, although once detected, plaque levels are greater with APOE4 than APOE3 (3).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Bales, 2009, Human APOE isoform-dependent effects on brain β-amyloid levels in PDAPP transgenic mice, J. Neurosci. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    APOE4 is the primary genetic risk factor for Alzheimer disease, increasing the risk by approximately 4-fold with a single allele and 15-fold with a double allele, whereas APOE2 reduces the risk compared with APOE3.

    “The primary genetic risk factor for Alzheimer disease (AD) 4 is APOE4, increasing the risk by ϳ4and 15-fold with a single or double allele, whereas APOE2 reduces the risk compared with APOE3.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] Drzezga, 2009, Effect of APOE genotype on amyloid plaque load and gray matter volume in Alzheimer disease, Neurology source

  • May combine two claims.

    Interpretationown data

    APOE genotype modulates Aβ speciation, an effect likely mediated by functional differences among the apoE isoforms.

    “Overall, these data demonstrate that APOE genotype modulates A␤ speciation, an effect likely mediated by functional differences among the apoE isoforms.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    Intraneuronal Aβ counts were counted by an investigator blinded to APOE genotype.

    “The number of neurons containing intraneuronal A␤ was determined using unbiased stereology (51) and counted by an investigator blinded to APOE genotype using sections immunostained with MOAB-2 (for A␤) and NeuN.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductcitation

    The oAβ ELISA detects synthetic oAβ preparations but not monomeric Aβ.

    “This ELISA pairing detects synthetic oA␤ preparations but not monomeric A␤ using preparations of oA␤ optimized for the original protocol (data not shown) (46).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [46] Moore, 2009, Biophysical analyses of synthetic amyloid-β(1–42) aggregates before and after covalent cross-linking. Implications for deducing the structure of endogenous amyloid-β oligomers, Biochemistry source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The difference in Aβ species measured (Aβ40 vs Aβ42) is one possible explanation for the discrepancy between the human study and EFAD mouse data.

    “which is one possible explanation for the discrepancy.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    Thio-S plaque staining and quantification was conducted by an investigator blinded to the APOE genotype.

    “Thio-S plaque staining and quantification was conducted by an investigator blinded to the APOE genotype using every ninth tissue section for six consecutive sections, beginning with the lateral-most section in the region of interest (ROI).”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Unbiased stereology was used for intraneuronal Aβ counts.

    “The number of neurons containing intraneuronal A␤ was determined using unbiased stereology (51) and counted by an investigator blinded to APOE genotype using sections immunostained with MOAB-2 (for A␤) and NeuN.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [51] West, 1991, Unbiased stereological estimation of the total number of neurons in thesubdivisions of the rat hippocampus using the optical fractionator, Anat. Rec. source

  • May combine two claims.

    Interpretationreasoning

    The proposed enhancement of Aβ toxicity by compact plaques would be enhanced with APOE4, as APOE4 is associated with a larger proportion of compact plaques.

    “This effect would be enhanced with APOE4, as it is associated with a larger proportion of compact plaques.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Experiments follow the University of Illinois at Chicago Institutional Animal Care and Use Committee protocols.

    “Experiments follow the University of Illinois at Chicago Institutional Animal Care and Use Committee protocols.”
    Quote in the paperNot a substantial claim
49 of 49

  • The paper relies on this without support.

    Human apoE in apoE-TR mice is expressed primarily by glia at physiologically regulated levels.

    “ApoE-TR mice are perhaps the most biologically relevant transgenic mouse model for apoE, as human apoE is expressed primarily by glia at physiologically regulated levels.”

  • The paper relies on this without support.

    APOE4 is the greatest risk factor for Alzheimer disease.

    “APOE4 is the greatest risk factor for Alzheimer disease (AD)”

  • The paper relies on this without support.

    It is unclear how the APOE genotype affects plaque morphology, intraneuronal Aβ, soluble Aβ42, and oligomeric Aβ (oAβ), particularly in vivo.

    “However, it remains unclear how the APOE genotype affects plaque morphology, intraneuronal A␤, soluble A␤42, and oligomeric A␤ (oA␤), particularly in vivo.”

  • The paper relies on this without support.

    No studies have yet reported the effect of APOE genotype on intraneuronal Aβ accumulation in an apoE/FAD-Tg mouse.

    “To our knowledge, no studies have yet reported the effect of APOE genotype on intraneuronal A␤ accumulation in an apoE/ FAD-Tg mouse.”

  • The paper relies on this without support.

    Introduction of human APOE significantly delays amyloid deposition in transgenic mice expressing familial AD (FAD) mutations.

    “As the introduction of human APOE significantly delays amyloid deposition in transgenic mice expressing familial AD (FAD) mutations (FAD-Tg)”

  • The paper relies on this without support.

    Intraneuronal Aβ has been correlated with cognitive deficits in FAD-Tg mice.

    “Indeed, intraneuronal A␤ has been correlated with cognitive deficits in FAD-Tg mice.”
6 of 6

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?

  • APOE4 was previously shown to accelerate AD progression in humans and in mouse models.

    “The APOE4 allele is a major genetic risk factor for late-onset AD and was previously shown to accelerate AD progression in humans and in mouse models 6-11 .”

    From APOE4 impairs the microglial response in Alzheimer’s disease by inducing TGFβ-mediated checkpoints (2023) · cites this paper as [10]

    The Discussion reports accelerated Aβ accumulation in E4FAD mice, supporting the mouse-model portion of the claim. The Abstract reports greater plaque deposition with APOE4 in humans and transgenic mice and identifies APOE4 as a major AD risk factor, but it does not establish accelerated clinical AD progression in humans. The paper's evidence is chiefly about amyloid pathology, not the full course of AD. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • The effect of APOE4 in Alzheimer disease is due not only to the increased propensity of proteins to aggregate in the presence of APOE4, but also to the way APOE4 modulates the brain response to those aggregates once formed.

    “These results bear a striking resemblance to those from the Aβ plaque-depositing mice120,128 and indicate that the effect of APOE4 in AD is due not only to the increased propensity of proteins to aggregate in the presence of APOE4, but also to the way APOE4 modulates the brain response to those aggregates once formed.”

    From Multifaceted roles of APOE in Alzheimer disease (2024) · cites this paper as [120]

    The Discussion reports that prior work found greater oligomeric Aβ-induced deficits in synaptic plasticity and neuronal viability with APOE4, which supports the idea of an altered response to aggregates. This paper’s own EFAD-mouse findings, however, concern Aβ accumulation and plaque morphology; it does not directly establish how the brain responds to formed aggregates, or extend that finding to proteins generally. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • E4FAD (APOE4+5xFAD) mice show increased amyloid deposition, specifically more compact plaques, compared to E3FAD (APOE3+5xFAD) mice.

    “Previous studies support this, with E4FAD (APOE4+5xFAD) mice showing increased amyloid deposition, specifically more compact plaques, compared to E3FAD (APOE3+5xFAD) mice (Youmans et al., 2012).”

    From Plcg2M28L Interacts With High Fat/High Sugar Diet to Accelerate Alzheimer’s Disease-Relevant Phenotypes in Mice (2022) · cites this paper as Youmans et al., 2012

  • The APOE4 allele is a major genetic risk factor for late-onset Alzheimer's disease.

    “The APOE4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease (AD).”

    From APOE4 impairs the microglial response in Alzheimer’s disease by inducing TGFβ-mediated checkpoints (2023) · cites this paper as [10]

  • Other studies have reported that APOE2 expression is associated with similar or even higher plaque load than APOE3.

    “Nevertheless other studies have also reported that APOE2 expression is associated with similar or even higher plaque load than APOE3 (Rodriguez et al, 2014; Youmans et al, 2012; Bales et al, 2009; Dodart et al, 2005).”

    From APOE from astrocytes restores Alzheimer’s Aβ-pathology and DAM-like responses in APOE deficient microglia (2024) · cites this paper as Youmans et al, 2012

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Self-check results appear here once an independent check has confirmed them.

Cited works that were retracted

Works this paper cites that were later retracted, from the retraction notices publishers deposit. Major when the notice came out before this paper was published.

  • Cites a retracted work: 10.1523/jneurosci.6637-10.2011

    Info

    The cited work was retracted on 2015-02-25 (notice 10.1523/jneurosci.5236-14.2015), not before this paper was published (2012-12).

    Cited work 10.1523/jneurosci.6637-10.2011 · retracted 2015-02-25 · notice 10.1523/jneurosci.5236-14.2015 · this paper published 2012-12

1 of 1

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Authors
Youmans, K. L., Tai, L. M., Nwabuisi-Heath, E., Jungbauer, L., Kanekiyo, T., Gan, M., Kim, J., Eimer, W. A., Estus, S., Rebeck, G. W., Weeber, E. J., Bu, G., Yu, C., & LaDu, M. J.
Affiliations
  • University of Illinois Chicago (US)
  • Mayo Clinic in Florida (US)
  • Washington University in St. Louis (US)
  • Northwestern University (US)
  • University of Kentucky (US)
  • Georgetown University (US)
  • University of South Florida (US)
Corresponding author
LaDu, Mary Jo
ORCID
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
2012-12
Volume
287
Issue
50
Pages
41774-41786
ISSN
0021-9258 (ISSN-L)
DOI
10.1074/jbc.m112.407957
PMC
PMC3516726
OpenAlex
W2168481427
Semantic Scholar
4a4316d49bb3198e00a5f0da10f93ed86c113688
Cited by
259
References
93
Citations by year
2026: 4 · 2025: 18 · 2024: 28 · 2023: 19 · 2022: 27 · 2021: 24 · 2020: 24 · 2019: 21 · 2018: 13 · 2017: 18 · 2016: 18 · 2015: 18 · 2014: 15 · 2013: 12
FWCI
8.52
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion)
  • PubMed Central (submittedVersion)
  • Rare & Special e-Zone (The Hong Kong University of Science and Technology) (submittedVersion)
Funders
  • Alzheimer's Association (P01AG030128-03S1, ZEN-08-899000, UL1RR029879)
  • National Institutes of Health (P01AG030128, UL1 RR-029879)
  • University of Illinois at Urbana-Champaign
  • National Institute on Aging (UL1RR029879, R01AG035355, P01 AG030128-03S1, T32‐AG036697, R01-AG027924, R01 AG035379, 5T32-AG036697, P01 AG030128)
  • National Institute of Neurological Disorders and Stroke (P01 NS074969)
  • National Center for Research Resources (UL1RR029879)
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
Keywords
APOE ε4, Alzheimer's disease, amyloid-beta deposition, APOE isoforms, 5xFAD mice, amyloid plaques, intraneuronal amyloid-beta, amyloid-beta oligomers, familial Alzheimer's disease
MeSH terms
Alzheimer Disease, Animals, Disease Models, Animal, Genotype, Humans, Mice, Transgenic, Mutation, Amyloid beta-Peptides, Protein Isoforms, Mice, Apolipoprotein E4

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.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

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Statistics and arithmetic are recomputed, not judged.

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