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Cited by 186Alzheimer's disease research and treatmentsDementia and Cognitive Impairment ResearchNeuroscience and Neuropharmacology Research

Human ApoE Isoforms Differentially Modulate Brain Glucose and Ketone Body Metabolism: Implications for Alzheimer's Disease Risk Reduction and Early Intervention

Open access
Wu, Long, Zhang, Xin, Zhao, Liqin·2018·The Journal of Neuroscience
DOI 10.1523/jneurosci.2262-17.2018PMC PMC6067075
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Abstract

Humans possess three genetic isoforms of apolipoprotein E (ApoE)—ApoE2, ApoE3, and ApoE4—that confer differential risk for Alzheimer9s disease (AD); however, the underlying mechanisms are poorly understood. This study sought to investigate the impact of human ApoE isoforms on brain energy metabolism, an area significantly perturbed in preclinical AD. A TaqMan custom array was performed to examine the expression of a total of 43 genes involved in glucose and ketone body transport and metabolism, focusing on pathways leading to the generation of acetyl-CoA, in human ApoE gene-targeted replacement female mice. Consistent with our previous findings, brains expressing ApoE2 exhibited the most robust profile, whereas brains expressing ApoE4 displayed the most deficient profile on the uptake and metabolism of glucose, the primary fuel for the brain. Specifically, the three ApoE brains differed significantly in facilitated glucose transporters, which mediate the entry of glucose into neurons, and hexokinases, which act as the “gateway enzyme” in glucose metabolism. Interestingly, on the uptake and metabolism of ketone bodies, the secondary energy source for the brain, ApoE2 and ApoE4 brains showed a similar level of robustness, whereas ApoE3 brains presented a relatively deficient profile. Further, ingenuity pathway analysis indicated that the PPAR-γ/PGC-1α signaling pathway could be activated in the ApoE2 brain and inhibited in the ApoE4 brain. Notably, PGC-1α overexpression ameliorated ApoE4-induced deficits in glycolysis and mitochondrial respiration. Overall, our data provide additional evidence that human ApoE isoforms differentially modulate brain bioenergetic metabolism, which could serve as a potential mechanism contributing to their discrete risk impact in AD. SIGNIFICANCE STATEMENT We uncovered hexokinase as a key cytosolic point in the glucose metabolism that is differentially modulated by the three ApoE genotypes. The differences in hexokinase expression and activity exhibited in the three ApoE brains may underlie their distinct impact on brain glucose utilization and further susceptibility to AD. Therefore, a therapeutic approach that could circumvent the deficiencies in the cytosolic metabolism of glucose by providing glucose metabolizing intermediates, e.g., pyruvate, may hold benefits for ApoE4 carriers, who are at high risk for AD. The bioenergetic robustness may translate into enhanced synaptic activity and, ultimately, reduces the risk of developing AD and/or delays the onset of clinical manifestation.

Integrity signals

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Crossref · 10.1523/jneurosci.2262-17.2018

Cites

48 of 48 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

34 of 62 cited sources checked · 18 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Forced expression of ApoE2 attenuated the progressive loss of synaptic integrity induced by ApoE4.

    “Forced expression of ApoE2 attenuated the progressive loss of synaptic integrity induced by ApoE4 (Klein et al., 2010).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Klein et al., 2010 source

      The Discussion reports that co-expression of apoE2 with apoE4 attenuated loss of synaptic activity in the lateral amygdala, but did not alter dendritic length. The Preparation of animals section describes apoE2/4 heterozygous targeted-replacement mice, not forced expression of apoE2. Thus the attenuation is supported for synaptic activity, but the stated intervention and broader implication for synaptic integrity are not fully supported. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Premisecitation

    A nonbiased proteomics study from the authors' laboratory revealed that the ApoE2 brain possessed the most robust regulatory mechanisms for synaptic transmission.

    “Recently, a nonbiased proteomics study from our laboratory revealed that the ApoE2 brain possessed the most robust regulatory mechanisms for synaptic transmission (Woody et al., 2016).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Woody et al., 2016 source
  • Premisecitation

    Cognitively normal individuals at risk for Alzheimer's disease, including ApoE4 carriers, show reduced cerebral metabolism of glucose.

    “Cognitively normal individuals at risk for AD, including those carrying ApoE4, showed reduced cerebral metabolism of glucose (Reiman et al., 2004(Reiman et al., , 2005)).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Reiman et al., 2004 source
    • cites Reiman et al., 2005 source
  • Interpretationcitation

    ApoE genetic status affects brain ketone body utilization.

    “Treatment with a ketogenic agent improved cognitive functions in ApoE3 carriers but not ApoE4 carriers (Reger et al., 2004;Henderson et al., 2009), suggesting that ApoE genetic status affects brain ketone body utilization.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Reger et al., 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Henderson et al., 2009 source

      The Results (Effect of APOE4 status; page unavailable) report improved ADAS-Cog scores with AC-1202 in APOE4 non-carriers, but no significant effect in carriers. The Discussion proposes that genotype-related differences in ketone transport into the brain could explain this response, while explicitly calling the mechanism speculative. The trial did not directly measure brain ketone utilization, and its comparison was APOE4 non-carriers versus carriers, not specifically ApoE3 versus ApoE4 carriers. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation

    Mouse brains expressing ApoE2 exhibited the most robust profile in insulin-like growth factor 1 signaling and glucose transport.

    “Further, a pathwayfocused gene profiling study revealed that mouse brains expressing ApoE2 exhibited the most robust profile in insulin-like growth factor 1 signaling and glucose transport (Keeney et al., 2015).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Keeney et al., 2015 source
  • May combine two claims. 29
  • Classified as probably not a substantial claim. 22

  • May combine two claims.

    Premisecitation

    Treatment with a ketogenic agent improved cognitive functions in ApoE3 carriers but not in ApoE4 carriers.

    “Treatment with a ketogenic agent improved cognitive functions in ApoE3 carriers but not ApoE4 carriers (Reger et al., 2004;Henderson et al., 2009), suggesting that ApoE genetic status affects brain ketone body utilization.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Reger et al., 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Henderson et al., 2009 source

      The Results (Effect of APOE4 status; page unavailable) report improved ADAS-Cog scores with AC-1202 in patients without APOE4, but no significant ADAS-Cog effect in APOE4 carriers. The paper stratified patients by APOE4 carriage, not APOE3 carriage, so it does not establish the claim specifically for all APOE3 carriers. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

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

    Study design and conductcitation

    Normalization factor calculation based on the geometric mean of multiple control genes was performed for selection of endogenous control genes.

    “Normalization factor calculation based on the geometric mean of multiple control genes was performed for selection of the endogenous control genes (Vandesompele et al., 2002).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Vandesompele et al., 2002 source

      The Results section on normalization-factor calculation recommends using the geometric mean of the most stable control genes and assessing whether additional genes improve the factor. But the Results section on gene-stability ranking says control genes are selected by their expression-stability measure M; the geometric-mean factor is calculated from selected genes, rather than being the primary method for selecting them. Our copy provides section labels but no page numbers. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

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

    Premisecitation

    ApoE4 exists in about 20% of the population but comprises nearly 65% of Alzheimer's disease cases.

    “In contrast, ApoE4 exists in 20% of the population; however it comprises nearly 65% of AD cases (Kim et al., 2009;Liu et al., 2013).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Kim et al., 2009 source

      The Genetics of ApoE in AD section identifies the ε4 allele as a strong genetic risk factor for Alzheimer’s disease. It does not give the claimed figures of 20% of the population or nearly 65% of AD cases; searches for those figures and for population and case prevalence found no supporting passage. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites Liu et al., 2013 source

      The Introduction (page not available) supports the underlying point that APOE ε4 is more common in AD: it reports an allele frequency of 13.7% worldwide and about 40% among patients with AD. It does not give the claimed percentages of people carrying APOE ε4 (20% of the population or nearly 65% of AD cases); allele frequency and carrier prevalence are different measures. The 65% in the Aβ deposition section refers to patients with positive PiB-PET scans, not to all AD cases. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    ApoE4 is associated with aggravated Alzheimer's disease neuropathology, enhanced neuroinflammation, deregulated lipid metabolism, mitochondrial dysfunction, and impaired synaptic plasticity.

    “On the molecular level, ApoE4 has been associated with aggravated AD neuropathology, enhanced neuroinflammation, deregulated lipid metabolism, mitochondrial dysfunction, and impaired synaptic plasticity (Nagy et al., 1995;Chang et al., 2005;Rapp et al., 2006;Klein et al., 2010;Rodriguez et al., 2014).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Nagy et al., 1995 source
    • cites Chang et al., 2005 source

      The Abstract links ApoE4 to AD risk and describes plaque formation and synaptic deficits among proposed mechanisms; the Results and Discussion report that ApoE4 fragments impair mitochondrial function. The paper does not establish enhanced neuroinflammation, deregulated lipid metabolism, or impaired synaptic plasticity specifically. The indexed passages do not provide page numbers. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites Rapp et al., 2006

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

    Premisecitation

    Overactivation of poly (ADP-ribose) polymerase-1 (PARP-1) resulted in the depletion of cytosolic NAD+ followed by inhibition of glycolysis, leading to sustained energy failure and ultimately cell death.

    “Suh et al. (2005) reported that the overactivation of poly (ADP-ribose) polymerase-1 (PARP-1) resulted in the depletion of cytosolic NAD ϩ followed by inhibition of glycolysis, leading to sustained energy failure and ultimately cell death.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Suh et al. (2005) source

      The available copy contains bibliographic information for Suh et al. (2005), but no passage addressing the proposed mechanism. Searches for PARP-1, cytosolic NAD+ depletion, glycolysis inhibition, and sustained energy failure found no relevant passage, so the attribution cannot be verified from this copy. (LLM, conf=0.76)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Clinical studies have shown that treatment with a ketogenic agent improved cognitive performance in AD patients, but the therapeutic benefits appeared to be confined to ApoE4 noncarriers.

    “Although clinical studies have shown that treatment with a ketogenic agent improved cognitive performance in AD patients, the therapeutic benefits appeared to be confined to ApoE4 noncarriers (Reger et al., 2004;Costantini et al., 2008;Henderson et al., 2009).”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites Reger et al., 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Costantini et al., 2008 source

      The Results section (‘AC-1202 in patients with cognitive impairments’) reports improved cognition in AD trials, with benefits most apparent in ApoE4-negative patients. The Conclusion says the effects were more marked in that subgroup, but does not say benefits were confined to noncarriers. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites Henderson et al., 2009 source

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

    Interpretationcitation

    Individuals with ApoE4 may be deficient in the transporters that control cellular uptake of ketone bodies or/and mitochondrial enzymes that convert ketone bodies to their metabolites.

    “Several clinical studies reported that ApoE4 carriers did not benefit from a ketogenic agent (Reger et al., 2004;Costantini et al., 2008), suggesting that individuals with ApoE4 may be deficient in the transporters that control the cellular uptake of ketone bodies or/and mitochondrial enzymes that convert the ketone bodies to their metabolites.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Reger et al., 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Costantini et al., 2008 source

      The Results (AC-1202 in patients with cognitive impairments; page unavailable) report greater cognitive improvement in ApoE4-negative than ApoE4-positive patients, and the Conclusion says AC-1202’s effects were more marked in the ApoE4-negative subgroup. The paper does not suggest that ApoE4 carriers are deficient in ketone-uptake transporters or mitochondrial enzymes; it offers differing dose responses, pathophysiology, or disease stage as possible explanations. (LLM, conf=0.85)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    PGC-1α downregulation has been associated with extensive alterations in several metabolic pathways, particularly oxidative phosphorylation and the mitochondrial electron transport chain.

    “PGC-1␣ downregulation has been associated with extensive alterations in several metabolic pathways, particularly in oxidative phosphorylation and the mitochondrial electron transport chain (Cui et al., 2006;Taherzadeh-Fard et al., 2009).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites Cui et al., 2006 source
    • cites Taherzadeh-Fard et al., 2009 source

      The Findings section (page not specified) reports that mutant huntingtin inhibits PGC-1α function and links this to mitochondrial dysfunction in Huntington disease. It also says PGC-1α regulates mitochondrial respiration, but does not describe extensive alterations across metabolic pathways or specifically identify oxidative phosphorylation and the electron transport chain as altered. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Forced expression of ApoE4 reduced mRNA and protein levels of Sirt1, an enzyme that mediates NAD+-dependent deacetylation of PGC-1α, thus enhancing its transcriptional activity.

    “Theendakara et al. (2013) reported that forced expression of ApoE4 reduced mRNA and protein levels of sirtuin 1 (Sirt1), an enzyme that mediates NAD ϩ -dependent deacetylation of PGC-1␣, thus enhancing its transcriptional activity (Canto ´and Auwerx, 2009).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites Theendakara et al. (2013) source
    • cites Canto ´and Auwerx, 2009 source

  • May combine two claims.

    Study design and conductcitation

    The advantage of using N2a cells was that the transfected cells expressed comparable human ApoE, which enabled comparisons of the three ApoE isoforms in parallel and precluded compounding complexity resulting from differences in ApoE expression levels as reported in hApoE-TR mice.

    “The advantage of using N2a cells was that the transfected cells expressed comparable human ApoE, which enabled the comparisons of the three ApoE isoforms in parallel and precluded compounding complexity resulting from the differences in ApoE expression levels as reported in the hApoE-TR mice (Riddell et al., 2008;Sullivan et al., 2011).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Riddell et al., 2008 source
    • cites Sullivan et al., 2011 source

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

    Premisecitation

    Brain ketone body uptake is mediated by monocarboxylic acid transporters (MCTs).

    “Brain ketone body uptake is mediated by the monocarboxylic acid transporters (MCTs; Pierre and Pellerin, 2005), and the metabolism of ketone bodies occurs exclusively in the mitochondria.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Pierre and Pellerin, 2005 source

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

    Premisecitation

    HK1 remains associated with mitochondria to promote glycolysis whereas HK2 dynamically translocates between cytosol and mitochondria where it directs the metabolic fate of glucose between anabolic and catabolic metabolism.

    “Additionally, it has been proposed that HK1 remains associated with mitochondria to promote glycolysis whereas HK2 dynamically translocates between cytosol and mitochondria where it directs the metabolic fate of glucose between anabolic (glycogen synthesis and pentose phosphate shunt) and catabolic (glycolysis) metabolism (Wilson, 2003;John et al., 2011).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Wilson, 2003 source

      The ‘Isozymes of mammalian hexokinase’ section proposes a glycolytic, energy-generating role for Type I and an anabolic role for Type II, including glycogen synthesis and the pentose phosphate pathway. The ‘Type II isozyme’ section reports both mitochondrial and non-mitochondrial Type II hexokinase, but does not establish dynamic translocation or say that movement between those locations directs glucose’s metabolic fate. The copy supports mitochondrial binding of Type I, not the stronger assertion that it remains associated. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites John et al., 2011 source

  • May combine two claims.

    Premisecitation

    As a direct substrate for mitochondrial metabolism, pyruvate can be oxidized in the absence of cytosolic NAD+; therefore, it can bypass the restrictions imposed by PARP-1 and thus restore energy deficiency.

    “As a direct substrate for mitochondrial metabolism, pyruvate can be oxidized in the absence of cytosolic NAD ϩ ; therefore, it can bypass the restrictions imposed by PARP-1 and thus restore energy deficiency (Zilberter et al., 2015).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Zilberter et al., 2015 source

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

    Premisecitation

    Both hexokinase isoforms are expressed in a variety of cell types; insulin-sensitive cells such as adult muscle cells express primarily HK2, whereas cells that rely heavily on glycolysis such as neurons express predominantly Hk1.

    “Although both hexokinase isoforms are expressed in a variety of cell types, cells that are sensitive to insulin, such as adult muscle cells, express primarily HK2, whereas cells that rely heavily on glycolysis for energy production, such as neurons, express predominantly Hk1 (Mandarino et al., 1995;Wilson, 2003).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Mandarino et al., 1995 source
    • cites Wilson, 2003 source

      In the “Isozymes of mammalian hexokinase” section (page not supplied), Wilson describes Type I as ubiquitous and particularly highly expressed in brain, and Type II as found primarily in insulin-sensitive tissues including skeletal muscle. The passage does not establish that HK1 predominates specifically in neurons or that HK2 is the predominant isoform in adult muscle cells; saying where an isoform is found primarily is not the same as saying it predominates there. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Glycolysis flow controlled V-ATPase reassembly after the addition of glucose into glucose-deprived cells.

    “Chan et al. (2016) reported that the glycolysis flow controlled V-ATPase reassembly after the addition of glucose into glucose-deprived cells.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Chan et al. (2016) source

  • Classified as probably not a substantial claim.

    Premisecitation

    Because neurons have a high energy requirement, their functionality depends heavily on glucose availability and utilization.

    “Because neurons have a high energy requirement, their functionality depends heavily on glucose availability and utilization (Mosconi, 2013).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Mosconi, 2013 source

  • May combine two claims.

    Findingown data

    Oligomycin-induced increase in ECAR was significantly larger in ApoE2-expressing cells than in ApoE3-expressing cells, suggesting higher maximum glycolytic capacity (FC=1.17, p=0.012).

    “Oligomycin-induced increase in ECAR was significantly larger, suggesting a higher maximum glycolytic capacity in ApoE2expressing cells than in ApoE3-expressing cells (FC ϭ 1.17, p ϭ 0.012).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The gene expression profile associated with ApoE4 appeared most distinct from ApoE2 and ApoE3 brains, while ApoE2 and ApoE3 brains shared some similarities.

    “Specifically, the gene expression profile associated with ApoE4 appeared most distinct from ApoE2 and ApoE3 brains; in comparison, ApoE2 and ApoE3 brains shared some similarities.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Hk1 protein levels were higher in ApoE2-transfected cells, but the difference was not statistically significant (FC=1.14, p=0.205).

    “Hk1 protein levels were also higher in ApoE2-transfected cells; however, the difference was not statistically significant (FC ϭ 1.14, p ϭ 0.205; Fig. 3D).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    The ApoE2 brain exhibits the most metabolically robust profile, whereas the ApoE4 brain presents the most deficient profile on the uptake and metabolism of glucose, the primary energy source for the brain.

    “The ApoE2 brain exhibits the most metabolically robust profile, whereas the ApoE4 brain presents the most deficient profile on the uptake and metabolism of glucose, the primary energy source for the brain.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Hexokinase is a key cytosolic point that the three ApoE isoforms differentially affect, which may contribute to their distinct impact on brain glucose utilization.

    “we pinpointed hexokinase as a key cytosolic point that the three ApoE isoforms differentially affect, which may contribute to their distinct impact on brain glucose utilization.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In N2a-ApoE cells, hexokinase activity was the highest in ApoE2 cells and the lowest in ApoE4 cells.

    “Hexokinase activity was the highest in N2a-ApoE2 cells, but the lowest in N2a-ApoE4 cells.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The ApoE2 and ApoE4 genotypes were associated with the most robust and deficient glycolytic function, respectively.

    “Specifically, the ApoE2 and ApoE4 genotypes were associated with the most robust and deficient glycolytic function”
    Quote in the paperSubstantial claim

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

    Study design and conductnone given

    Differentiated N2a cells were defined by neuron-like morphology and enhanced protein expressions of neuronal markers such as NeuN, synaptophysin, and PSD95.

    “Differentiated N2a cells were defined by neuron-like morphology and the enhanced protein expressions of neuronal markers such as NeuN, synaptophysin, and PSD95.”
    Quote in the paperNot a substantial claim

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

    Study design and conductnone given

    Band densities were quantified using Image Studio v4.0 with signal normalized to loading control proteins.

    “Band densities were quantified using Image Studio v4.0 image digitizing software with signal normalized to loading control proteins.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    ApoE2 slows Alzheimer's disease progression and is positively associated with cognitive functions during aging.

    “ApoE2 has been found to slow AD progression and be positively associated with cognitive functions during aging (Nagy et al., 1995;Craft et al., 1998;Martins et al., 2005;Shinohara et al., 2016).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Nagy et al., 1995 source
    • cites Craft et al., 1998 source
    • cites Martins et al., 2005 source

  • Classified as probably not a substantial claim.

    Study design and conductown data

    Cell lines stably expressing ApoE at similar levels, as determined by immunoblotting analysis, were used in the study.

    “Cell lines stably expressing ApoE at similar levels, as determined by immunoblotting analysis, were used in the study.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Human apolipoprotein E (ApoE) genetic polymorphism confers differential susceptibility to late-onset Alzheimer's disease, which accounts for the majority of AD cases.

    “The genetic polymorphism of human apolipoprotein E (ApoE) has been shown to confer differential susceptibility to late-onset AD, which accounts for the majority of the AD cases (Farrer et al., 1997).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Farrer et al., 1997 source

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

    Study design and conductown data

    The 2−ΔCt values for each target gene between two ApoE genotype groups were statistically compared using Student's t test; p<0.05 was considered statistically significant, and p values were adjusted by Bonferroni correction.

    “The 2 Ϫ⌬Ct values for each target gene between two ApoE genotype groups were statistically compared using Student's t test; p Ͻ 0.05 was considered statistically significant.The p values were adjusted by Bonferroni correction.”
    Quote in the paperSubstantial claim

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

    Study design and conductnone given

    RNA samples with RNA integrity number greater or equal to 8 were converted to cDNA.

    “RNA samples with RNA integrity number greater or equal to 8 were converted to cDNA using the High Capacity RNA-to-cDNA Master Mix (Applied Biosystems) on a T100 thermocycler (Bio-Rad).”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    One-way ANOVA with Bonferroni post hoc test were performed to compare mean values among the three ApoE genotype groups.

    “Oneway ANOVA with Bonferroni post hoc test were performed to compare mean values among the three ApoE genotype groups.”
    Quote in the paperSubstantial claim

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

    Study design and conductnone given

    Each experiment was performed independently at least three times.

    “Each experiment was performed independently at least three times.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    ApoE2 is rare, occurring in about 5% of the population, and shows protection against Alzheimer's disease.

    “ApoE2 is rare, occurring in 5% of the population, and it shows protection against AD.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Nagy et al., 1995 source
    • cites Craft et al., 1998 source
    • cites Martins et al., 2005 source

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

    Study design and conductown data

    The primers used for PCR amplification for each ApoE genotype were highly specific, with a difference in Ct value between positive and negative of at least 11 cycles, suggesting specific amplifications are 2048-fold more efficient than nonspecific ones.

    “The primers used for PCR amplification for each genotype were highly specific as the difference in Ct value between positive and negative was at least 11 cycles, suggesting that the specific amplifications are 2048-fold more efficient than the nonspecific ones (Fig. 3B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    In addition to lower protein expression, the activity of PGC-1α may also be diminished in ApoE4 brains.

    “In addition to lower protein expression, the activity of PGC-1␣ may also be diminished.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Significant reduction in glucose transport across the blood-brain barrier without altered mRNA or protein expression of GLUT1 has been reported in hApoE4-TR mice, suggesting that the function of GLUT1 may involve post-translational modification.

    “significant reduction in glucose transport across the blood-brain barrier without altered mRNA or protein expression of GLUT1 has been reported in hApoE4-TR mice, suggesting that the function of GLUT1 may involve post-translational modification (Alata et al., 2015).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Alata et al., 2015

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

    Premisecitation

    Several glycolytic enzymes have been found in nerve terminals where they interact with subunits of V-type H+-ATPase (V-ATPase), a proton pump that mediates the concentration of neurotransmitters into synaptic vesicles, which is crucial for synaptic transmission.

    “Several glycolytic enzymes have been found in the nerve terminals where they interact with the subunits of V-type H ϩ -ATPase (V-ATPase), a proton pump that mediates the con-centration of neurotransmitters into synaptic vesicles, which therefore is crucial for synaptic transmission (Lu et al., 2004).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Lu et al., 2004

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationreasoning

    ApoE2 may modulate PGC-1α activity through a similar mechanism.

    “However, ApoE2 may modulate PGC-1␣ activity through a similar mechanism.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    ApoE4 brains might be deficient in ketone body transport and/or key enzymes that metabolize ketone bodies.

    “This suggests that ApoE4 brains might be deficient in ketone body transport and/or key enzymes that metabolize ketone bodies.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Lower expression of Sirt1 may result in reduced PGC-1α activation, which may underlie the bioenergetic deficits associated with ApoE4.

    “Therefore, lower expression of Sirt1 may result in reduced PGC-1␣ activation, which may underlie the bioenergetic deficits associated with ApoE4.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The glycolytic robustness exhibited in ApoE2-expressing brains may translate into enhanced synaptic activity and ultimately the clinically proven cognition-favoring and anti-AD properties associated with this genotype.

    “The glycolytic robustness exhibited in ApoE2-expressing brains may translate into enhanced synaptic activity and ultimately the clinically proven cognition-favoring and anti-AD properties associated with this genotype.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    One major concern was the utilization of a neuroblastoma cell line, which may have altered metabolic phenotype compared with postmitotic neurons.

    “One major concern was the utilization of a neuroblastoma cell line, which may have altered metabolic phenotype compared with postmitotic neurons.”
    Quote in the paperSubstantial claim
42 of 42

  • The paper relies on this without support.

    ApoE3 is risk-neutral and present in about 75% of the population.

    “The most common isoform, ApoE3, is present in ϳ75% of the population and is believed to be risk-neutral.”

  • The paper relies on this without support.

    Protection against Alzheimer's disease should greatly precede Alzheimer's disease onset.

    “It has been proposed that protection against AD should greatly precede AD onset.”

  • The paper relies on this without support.

    Preclinical Alzheimer's disease can last 10–20 years before its clinical manifestation.

    “Indeed, the preclinical development of AD could last 10 -20 years before its clinical manifestation.”

  • The paper relies on this without support.

    The hApoE-TR mouse model expresses human ApoE protein at levels similar to human tissue in the brain regions most affected by Alzheimer's disease.

    “These mice express levels of human ApoE protein similar to human tissue in the brain regions that are most affected by AD.”

  • The paper relies on this without support.

    Ketone body metabolism occurs exclusively in mitochondria.

    “Brain ketone body uptake is mediated by the monocarboxylic acid transporters (MCTs; Pierre and Pellerin, 2005), and the metabolism of ketone bodies occurs exclusively in the mitochondria.”

  • The paper relies on this without support.

    PGC-1α is the master regulator of mitochondrial biogenesis and oxidative phosphorylation.

    “Given that PGC-1␣ is the master regulator of mitochondrial biogenesis and oxidative phosphorylation, we also examined the effect of PGC-1␣ overexpression on mitochondrial respiration in cells stably expressing ApoE4.”

  • The paper relies on this without support.

    The N2a cell model is a valid model for neuronal glucose and ketone body metabolism.

    “We used cell models expressing human ApoE2, ApoE3, and ApoE4 (N2a-ApoE2, N2a-ApoE3, and N2a-ApoE4) to further study how ApoE isoforms modulate glucose metabolism, focusing on hexokinase and glycolysis.”

  • The paper relies on this without support.

    The 43 genes examined in the TaqMan array represent the pathways of glucose and ketone body transport and metabolism.

    “A TaqMan custom array was performed to examine the expression of a total of 43 genes involved in glucose and ketone body transport and metabolism, focusing on pathways leading to the generation of acetyl-CoA, in human ApoE gene-targeted replacement female mice.”

  • The paper relies on this without support.

    IPA upstream regulator predictions reflect true biological regulator activity.

    “IPA upstream regulator analysis identifies transcriptional regulators of the genes in the dataset, which could explain the observed gene expression changes.The analysis predicts likely relevant upstream molecules by assessing how many known downstream targets are present.”

  • The paper relies on this without support.

    Human ApoE isoforms confer differential risk in late-onset AD, which comprises 95% of total AD cases.

    “Human ApoE isoforms have been shown to confer differential risk in late-onset AD, which comprises 95% of total AD cases.”

  • The paper relies on this without support.

    The underlying mechanisms by which ApoE2 confers neuroprotection remain largely unexplored.

    “However, the underlying mechanisms by which ApoE2 confers neuroprotection remain largely unexplored.”

  • The paper relies on this without support.

    Under normal physiological conditions, glucose is the sole substrate for energy production in the brain.

    “Under normal physiological conditions, glucose is the sole substrate for energy production in the brain.”

  • The paper relies on this without support.

    The availability of glucose to cells is governed by the facilitated glucose transporters (GLUTs).

    “The availability of glucose to cells is governed by the facilitated glucose transporters (GLUTs).”

  • The paper relies on this without support.

    ATP generated by glycolysis only accounts for a small percentage of total energy used in the brain.

    “Despite the fact that ATP generated by glycolysis only accounts for a small percentage of total energy used in the brain”

  • The paper relies on this without support.

    Emerging evidence suggests that glycolysis plays a crucial role in maintaining synaptic functions.

    “emerging evidence suggests that glycolysis plays a crucial role in maintaining synaptic functions.”

  • The paper relies on this without support.

    To date, there is no report on Sirt1 expression and transcriptional regulation in the ApoE2 genotype.

    “To date, there is no report on Sirt1 expression and transcriptional regulation in the ApoE2 genotype.”
16 of 16

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?

  • None of the previous studies attempted to provide causality among these pathological features and to restore the defects by ApoE4, especially in human astrocytes.

    “However, none of these studies attempted to provide the causality among these pathological features and to restore the defects by ApoE4, especially in human astrocytes.”

    From ApoE4-dependent lysosomal cholesterol accumulation impairs mitochondrial homeostasis and oxidative phosphorylation in human astrocytes (2023) · cites this paper as [23]

    The Results section reports an intervention aimed at reversing ApoE4-associated deficits: PGC-1α overexpression in ApoE4-expressing N2a cells improved hexokinase activity and reversed defects in glycolytic reserve capacity. This contradicts the claim that none of the studies attempted to restore ApoE4-related defects. The experiment used N2a cells, not human astrocytes; our copy does not establish the broader claim about all previous studies. (LLM, conf=0.86)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured

  • Previous studies reported altered glucose metabolism, dysregulated lipid homeostasis, and lysosomal/autophagosomal impairments by ApoE4 in various cell types, including neurons and astrocytes.

    “altered glucose metabolism, dysregulated lipid homeostasis, and lysosomal/autophagosomal impairments by ApoE4 in various cell types, including neurons and astrocytes.”

    From ApoE4-dependent lysosomal cholesterol accumulation impairs mitochondrial homeostasis and oxidative phosphorylation in human astrocytes (2023) · cites this paper as [23]

    The Abstract and Discussion report deficient glucose uptake and metabolism in ApoE4-expressing brains, and the Introduction associates ApoE4 with deregulated lipid metabolism. Our copy does not establish ApoE4-related lysosomal or autophagosomal impairment, or the full set of claimed effects in both neurons and astrocytes. (LLM, conf=0.87)

    Experimental — accuracy not yet measured

  • In human ApoE gene-targeted female replacement mice, apoE status affects brain glucose and ketone metabolism, and apoE4 is the most harmful for glucose metabolism.

    “Studies on human ApoE gene-targeted female replacement mice show that apoE status appears to influence brain glucose and ketone metabolism, with the apoE4 allele being the most deleterious for the former103.”

    From Oxidative stress, dysfunctional glucose metabolism and Alzheimer disease (2019) · cites this paper as [103]

  • APOE4 expression causes altered genetic expression of glucose-regulating enzymes and transporters.

    “altered genetic expression of glucose-regulating enzymes and transporters23,24”

    From APOE4 is Associated with Differential Regional Vulnerability to Bioenergetic Deficits in Aged APOE Mice (2020) · cites this paper as [24]

  • Mice expressing human apoE4 show deficient uptake and metabolism of glucose in the brain.

    “Mice expressing human apoE4 show deficient uptake and metabolism of glucose in the brain [33].”

    From Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function (2019) · cites this paper as [33]

Self-check

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

Each contradiction between two passages listed here was confirmed by an independent check.

  • ApoE2 and ApoE4 clone mutations conflict with the genotyping primers

    Major

    The clone description assigns the T-to-C substitution at position 388 to ApoE2 and the C-to-T substitution at position 526 to ApoE4. The genotype-specific primers show the opposite pattern relative to ApoE3: ApoE4 has the T-to-C difference in the forward primer, while ApoE2 has the C-to-T difference indicated by the reverse primer. This calls the stated identities of the constructed clones into question.

  • Figure 4 assigns ATP measurements to different panels

    Minor

    The Results direct readers to Figure 4B for ATP levels, whereas the Figure 4 legend assigns ATP levels to panel F and describes panels A and B as glycolytic stress tests.

  • ApoE gene-expression assay describes genomic DNA rather than RNA

    Minor

    The methods say this PCR assay measured ApoE gene expression after transfection, but specify genomic DNA as its input. Amplifying genomic DNA does not measure gene expression.

3 of 3

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Authors
Wu, L., Zhang, X., & Zhao, L.
Affiliations
University of Kansas (US)
ORCID
Venue
The Journal of Neuroscience
Publisher
Society for Neuroscience
Published
2018-07-02
Volume
38
Issue
30
Pages
6665-6681
ISSN
  • 0270-6474 (ISSN-L)
  • 1529-2401
DOI
10.1523/jneurosci.2262-17.2018
PMC
PMC6067075
OpenAlex
W2811122574
Cited by
185
References
48
Citations by year
2026: 19 · 2025: 20 · 2024: 15 · 2023: 32 · 2022: 32 · 2021: 24 · 2020: 24 · 2019: 17 · 2018: 2
FWCI
11.48
Type
journal article
Language
en
Open access
Locations
  • Journal of Neuroscience (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • National Institute on Aging (R21AG055964, P30AG035982, P30AG072973)
  • National Institute of General Medical Sciences (P30GM110761, P20GM103418)
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 › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
Keywords
apolipoprotein E isoforms, APOE2, APOE3, APOE ε4, Alzheimer's disease risk, brain glucose metabolism, ketone body metabolism, brain energy metabolism, hexokinase, glucose transporters, mitochondrial respiration, glycolysis, pyruvate supplementation
MeSH terms
Alzheimer Disease, Animals, Apolipoproteins E, Brain, Energy Metabolism, Female, Glucose, Humans, Ketone Bodies, Mice, Transgenic, Risk, Protein Isoforms, Mice

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 2026-11-02.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-11-02.

Cited sources are checked by gpt-6-sol.

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.

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