APOE4 Increases Energy Metabolism in APOE-Isogenic iPSC-Derived Neurons

Classified as probably not a substantial claim.

APOE4 is the major genetic risk factor for Alzheimer's disease.

“The apolipoprotein E4 (APOE4) allele represents the major genetic risk factor for Alzheimer’s disease (AD).”

• Also stated in: § 1. Introduction · boosted

  “Among them, the APOE4 allele represents the strongest risk factor.”

• cites [2] Andrews, S.J., Renton, A.E., Fulton-Howard, B., Podlesny-Drabiniok, A., Marcora, E., and Goate, A.M. (2023). The Complex Genetic Architecture of Alzheimer’s Disease: Novel Insights and Future Directions. eBioMedicine, 90. sourcePartly supported

  The section on Alzheimer’s disease genetics in diverse populations reports that APOE was the only locus to reach genome-wide significance in one study, and the section on microglial efferocytosis discusses APOE4’s disease-related effects. These passages support APOE4’s importance, but our copy does not explicitly establish that the APOE4 allele is the major genetic risk factor for AD overall. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

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

APOE is primarily expressed by astrocytes in the brain, but neurons have also been shown as a source for APOE.

“Although APOE is primarily expressed by astrocytes in the brain, neurons have also been shown as source for APOE.”

• Also stated in: § 1. Introduction · plain

  “In the brain, APOE is mainly expressed by astrocytes, but also microglia and neurons have been shown to secrete APOE.”

• cites [4] Blumenfeld, 2024, Cell Type-Specific Roles of APOE4 in Alzheimer Disease, Nat. Rev. Neurosci. sourceSupported

May combine two claims.

Hexokinase (HK) expression is decreased in APOE4 cells with higher passages, whereas APOE2 and APOE3 showed stable expression of HK over time.

“This effect could also be observed for hexokinase (HK) expression, which is decreased in APOE4 cells with higher passages, whereas APOE2 and APOE3 showed stable expression of HK over time [28].”

• cites [28] Zhang, X., Wu, L., Swerdlow, R.H., and Zhao, L. (2023). Opposing Effects of ApoE2 and ApoE4 on Glycolytic Metabolism in Neuronal Aging Supports a Warburg Neuroprotective Cascade against Alzheimer’s Disease. Cells, 12. sourceSupported

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

Qi and colleagues suggested a cell-type-specific APOE effect on glycolysis, showing reduced ATP levels and glycolysis in primary hippocampal neurons and increased glycolytic rates and ATP production in astrocytes.

“Qi and colleagues suggested a cell-type-specific APOE effect on glycolysis, showing reduced ATP levels and glycolysis in primary hippocampal neurons and increased glycolytic rates and ATP production in astrocytes [29].”

• cites [29] Qi, 2021, ApoE4 Impairs Neuron-Astrocyte Coupling of Fatty Acid Metabolism, Cell Rep. sourcePartly supported

  The Results sections on ApoE4 neurons and astrocytic fatty-acid degradation report lower cellular ATP in E4 neurons and higher glycolytic rates and ATP levels in E4 astrocytes. The paper reports reduced neuronal glucose uptake and glucose-dependent oxidative phosphorylation, but does not establish reduced glycolysis in primary hippocampal neurons as a direct ApoE4 effect. It measures higher astrocyte ATP levels, not ATP production rates; page numbers are unavailable in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

An early hypermetabolism may drive AD pathology, including amyloid production and aggregation as well as tau phosphorylation and accumulation, which leads to neurodegeneration.

“The reason may be that an early hypermetabolism drives AD pathology, including amyloid production and aggregation as well as tau phosphorylation and accumulation, which leads to neurodegeneration [48].”

• cites [48] Nuriel, 2017, Neuronal Hyperactivity Due to Loss of Inhibitory Tone in APOE4 Mice Lacking Alzheimer’s Disease-like Pathology, Nat. Commun. sourcePartly supported

  The Discussion proposes that APOE4-associated hyperactivity may drive Aβ and tau accumulation, followed by neurodegeneration, and reports that increased neuronal activity raises Aβ production. It does not specifically link hyperactivity to tau phosphorylation or establish that it causes amyloid aggregation. The proposed sequence is a hypothesis, not a demonstrated outcome in these mice. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

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

APOE4 primary hippocampal neurons from mice showed lower maximal respiration and spare respiratory capacity ratios, as well as lower mitochondrial membrane potential, reduced expression of complex subunits, and reduced ATP levels.

“APOE4 primary hippocampal neurons from mice showed lower maximal respiration and spare respiratory capacity ratios, as well as lower mitochondrial membrane potential, reduced expression of complex subunits, and reduced ATP levels. [29].”

• cites [29] Qi, 2021, ApoE4 Impairs Neuron-Astrocyte Coupling of Fatty Acid Metabolism, Cell Rep. sourceSupported

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

Many contradictory results on the impact of APOE on energy metabolism have been published.

“In general, many contradictory results on the impact of APOE on energy metabolism have been published.”

• cites [28] Zhang, X., Wu, L., Swerdlow, R.H., and Zhao, L. (2023). Opposing Effects of ApoE2 and ApoE4 on Glycolytic Metabolism in Neuronal Aging Supports a Warburg Neuroprotective Cascade against Alzheimer’s Disease. Cells, 12. sourceSupported
• cites [39] Fang, 2021, APOE4 Genotype Exacerbates the Depression-like Behavior of Mice during Aging through ATP Decline, Transl. Psychiatry sourceCould not verify

  The Introduction describes reports of reduced brain glucose metabolism in APOE ε4 carriers, and the Results and Discussion describe this study’s age- or culture-dependent findings. None of those passages says that many published findings on APOE and energy metabolism contradict one another; searches for contradictory or inconsistent findings did not locate such a discussion. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [40] Lee, 2023, ApoE4-Dependent Lysosomal Cholesterol Accumulation Impairs Mitochondrial Homeostasis and Oxidative Phosphorylation in Human Astrocytes, Cell Rep. sourceCould not verify

  The Introduction describes altered metabolism in ApoE4 carriers and says its causal relationship with glucose metabolism remains elusive. The Results report findings consistent with previous studies, but the passages found do not say that many published results on APOE and energy metabolism contradict one another. I searched for contradictory or conflicting findings and comparisons with previous studies. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites [41] Farmer, 2021, APOΕ4 Lowers Energy Expenditure in Females and Impairs Glucose Oxidation by Increasing Flux through Aerobic Glycolysis, Mol. Neurodegener. sourceCould not verify

  The Background discusses prior findings on APOE and metabolism but does not describe them as contradictory. A search for conflicting or inconsistent results found no passage in our copy establishing that many contradictory findings have been published. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [42] Sonntag, 2017, Late-Onset Alzheimer’s Disease Is Associated with Inherent Changes in Bioenergetics Profiles, Sci. Rep. sourceCould not verify

  The Discussion (page unavailable) says Apoε4 has been implicated in damaging the oxidative system, but does not say that published findings on APOE and energy metabolism are contradictory. Searches for contradictory or inconsistent APOE findings found no passage addressing that point. (LLM, conf=0.72)

  Experimental — accuracy not yet measured

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

APOE-dependent alterations in mitochondrial fusion/fission protein levels have been shown in other studies; however, those were contradictory.

“In contrast, APOE-dependent alterations in mitochondrial fusion/fission protein levels have been shown in other studies; however, those were contradictory.”

• cites [37] Wang, 2008, Dynamin-like Protein 1 Reduction Underlies Mitochondrial Morphology and Distribution Abnormalities in Fibroblasts from Sporadic Alzheimer’s Disease Patients, Am. J. Pathol. sourceCould not verify

  The section on wild-type and Swedish-mutant APP reports reduced DLP1 levels after APP overexpression, not APOE-dependent changes. The passages on mitochondrial fission and fusion do not report contradictory findings from other studies. Searches for APOE-dependent effects and apolipoprotein E genotype found no passage addressing either part of the claim. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [38] Yin, 2020, Effect of ApoE Isoforms on Mitochondria in Alzheimer Disease, Neurology sourcePartly supported

  The Results (p. e2406) report lower levels of the fusion/fission proteins MFN1, MFN2, and DLP1 in ApoE-ε4 carriers than in noncarriers. This supports APOE-dependent alterations, but the paper presents them as its own findings; the passages reviewed do not establish that other studies found contradictory results. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [33] Orr, 2019, Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function, J. Alzheimer’s Dis. sourcePartly supported

  The Results (Fig. 9; page unavailable) and Discussion report that apoE4 altered levels of mitochondrial fusion/fission proteins in this study. They do not say that other studies found such alterations or that those studies contradicted one another. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

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

OPA1 appears as two bands, L-OPA1 and S-OPA1, which cooperate during mitochondrial fusion.

“Both isoforms have been described to cooperate during mitochondrial fusion [16] and were quantified together.”

• cites [16] Ge, 2020, Two Forms of Opa1 Cooperate to Complete Fusion of the Mitochondrial Inner-Membrane, eLife sourceSupported

May combine two claims.

In astrocytes from the same iPSC lines, APOE-KO astrocytes showed a similar response in glutamate and Aβ uptake, cholesterol, and lipid metabolism, as well as an inflammatory response to APOE2 but not to APOE4 astrocytes.

“This was also observed in astrocytes from the same iPSC lines, where APOE-KO astrocytes showed a similar response in glutamate and Aβ uptake, cholesterol, and lipid metabolism, as well as an inflammatory response to APOE2 but not to APOE4 astrocytes [13].”

• cites [13] Kirschner, 2022, APOE2, E3, and E4 Differentially Modulate Cellular Homeostasis, Cholesterol Metabolism, and Inflammatory Response in Isogenic iPSC-Derived Astrocytes, Stem Cell Rep. sourcePartly supported

  The Results and Discussion sections on homeostatic functions report that APOE-KO and APOE2 astrocytes had similar glutamate uptake and an Aβ42 uptake pattern distinct from APOE4. The Results on cholesterol and lipid metabolism show a mixed picture: some protein levels were similar in KO and E2, but cellular and total cholesterol were similar in KO and E4, not E2. The inflammatory-response Results report lower cytokine release in KO than E2 after stimulation, although both were less affected than E4. Page numbers were not available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

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

Astrocytic APOE makes up 75-80% of total brain APOE while neurons contribute 15-20%.

“Studies on the selective removal of APOE from the mouse brain indicated that astrocytic APOE makes up 75–80% of total brain APOE while neurons contribute 15–20% [4].”

• cites [4] Blumenfeld, 2024, Cell Type-Specific Roles of APOE4 in Alzheimer Disease, Nat. Rev. Neurosci. sourceSupported

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

Neuronal APOE4 expression reduced the levels of mitochondrial respiratory complex subunits compared to APOE3 neurons.

“Neuronal APOE4 expression reduced the levels of mitochondrial respiratory complex subunits compared to APOE3 neurons [32,33].”

• cites [32] Chen, 2011, Apolipoprotein E4 Domain Interaction Mediates Detrimental Effects on Mitochondria and Is a Potential Therapeutic Target for Alzheimer Disease, J. Biol. Chem. sourceSupported
• cites [33] Orr, 2019, Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function, J. Alzheimer’s Dis. sourceSupported

May combine two claims.

Human iN cell fusion and fission are stable mechanisms that are not affected by other mitochondrial dysfunctions.

“This is in agreement with a previous study showing altered levels of ETC complexes in iN cells from AD patients in the absence of fusion and fission alterations [14], suggesting that human iN cell fusion and fission are stable mechanisms that are not affected by other mitochondrial dysfunctions.”

• cites [14] Birnbaum, 2018, Oxidative Stress and Altered Mitochondrial Protein Expression in the Absence of Amyloid-Beta and Tau Pathology in iPSC-Derived Neurons from Sporadic Alzheimer’s Disease Patients, Stem Cell Res. sourcePartly supported

  The Results report altered oxidative phosphorylation complex composition without changes in most measured fusion and fission markers in the AD patient-derived iN cells. They also report lower OPA1 mRNA in one patient cell line. These observations do not establish that fusion and fission are generally stable mechanisms unaffected by other mitochondrial dysfunctions. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

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

Astrocytes secrete approx. 50-60% of the APOE they produce, while neurons retain most APOE intracellularly and only secrete approx. 10%.

“Astrocytes secrete approx. 50–60% of the APOE they produce, while neurons retain most APOE intracellularly and only secrete approx. 10% [5,6]”

• cites [5] Lanfranco, 2021, Expression and Secretion of apoE Isoforms in Astrocytes and Microglia during Inflammation, Glia sourcePartly supported

  The Results section (‘ApoE species differ between astrocytes and microglia’; page unavailable) reports that astrocytes secreted 50–60% of the apoE they produced. The paper studies astrocytes and microglia, not neuronal secretion; its Discussion mentions apoE expression in injured neurons but gives no evidence that neurons retain most apoE or secrete approximately 10%. (LLM, conf=0.90)

  Experimental — accuracy not yet measured
• cites [6] Harris, 2004, Astroglial Regulation of Apolipoprotein E Expression in Neuronal Cells. Implications for Alzheimer’s Disease, J. Biol. Chem. sourcePartly supported

  The passage accompanying Fig. 6 reports that approximately 10% of apoE produced by mouse primary cortical neurons was secreted during 24 hours, supporting the neuronal part of the claim. It reports that more than 60% of apoE produced by mouse primary astrocytes was secreted, rather than approximately 50–60%. The measurements are from cultured mouse cells. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

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

Mitochondrial fusion is particularly important in respiratory active cells, such as neurons.

“Mitochondrial fusion is particularly important in respiratory active cells, such as neurons [36].”

• cites [36] Westermann, 2012, Bioenergetic Role of Mitochondrial Fusion and Fission, Biochim. Biophys. Acta (BBA)—Bioenerg. sourceSupported

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

MFN1, MFN2, OPA1, and FIS1 levels were decreased in the brains and neurons of AD patients and APOE4 carriers.

“MFN1, MFN2, OPA1, and FIS1 levels were decreased in the brains and neurons of AD patients and APOE4 carriers [37,38], whereas APOE4 N2A cells expressed higher levels of fission and fusion proteins than APOE3 N2A cells [33].”

• cites [37] Wang, 2008, Dynamin-like Protein 1 Reduction Underlies Mitochondrial Morphology and Distribution Abnormalities in Fibroblasts from Sporadic Alzheimer’s Disease Patients, Am. J. Pathol. sourceCould not verify

  The “DLP1 Level Change in sAD Fibroblasts” section reports reduced DLP1 but no significant change in OPA1 in fibroblasts. Our copy does not report MFN1, MFN2, OPA1, or FIS1 levels in AD brains or neurons or in APOE4 carriers (searched for the named proteins, brain, neurons, and APOE4). The fibroblast result does not establish or contradict the claimed findings in those other populations. (LLM, conf=0.78)

  Experimental — accuracy not yet measured
• cites [38] Yin, 2020, Effect of ApoE Isoforms on Mitochondria in Alzheimer Disease, Neurology sourcePartly supported

  The Results (pp. e2406–e2407, Figure 1) report lower MFN1 and MFN2 levels in postmortem middle temporal gyrus tissue from APOE4 carriers than noncarriers, and from patients with AD than cognitively normal controls. The paper measured DLP1, not OPA1 or FIS1, and does not report these findings in isolated neurons. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

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

Reprogramming into iPSCs results in a glycolytic signature.

“This aligns with earlier studies showing that the process of reprograming into iPSCs results in a glycolytic signature [23].”

• cites [23] Varum, S., Rodrigues, A.S., Moura, M.B., Momcilovic, O., Easley, C.A., Ramalho-Santos, J., Van Houten, B., and Schatten, G. (2011). Energy Metabolism in Human Pluripotent Stem Cells and Their Differentiated Counterparts. PLoS ONE, 6. sourceSupported

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

Some studies found that APOE4 reduced glycolysis, whereas others observed a shift from oxidative to glycolytic metabolism in APOE4 cells with higher glycolytic activity in APOE4 than APOE3.

“Some studies found that APOE4 reduced glycolysis [28,39], whereas others observed a shift from oxidative to glycolytic metabolism in APOE4 cells with higher glycolytic activity in APOE4 than APOE3 [40,41,42].”

• cites [28] Zhang, X., Wu, L., Swerdlow, R.H., and Zhao, L. (2023). Opposing Effects of ApoE2 and ApoE4 on Glycolytic Metabolism in Neuronal Aging Supports a Warburg Neuroprotective Cascade against Alzheimer’s Disease. Cells, 12. sourceSupported
• cites [39] Fang, 2021, APOE4 Genotype Exacerbates the Depression-like Behavior of Mice during Aging through ATP Decline, Transl. Psychiatry sourceSupported
• cites [40] Lee, 2023, ApoE4-Dependent Lysosomal Cholesterol Accumulation Impairs Mitochondrial Homeostasis and Oxidative Phosphorylation in Human Astrocytes, Cell Rep. sourceSupported
• cites [41] Farmer, 2021, APOΕ4 Lowers Energy Expenditure in Females and Impairs Glucose Oxidation by Increasing Flux through Aerobic Glycolysis, Mol. Neurodegener. sourceSupported
• cites [42] Sonntag, 2017, Late-Onset Alzheimer’s Disease Is Associated with Inherent Changes in Bioenergetics Profiles, Sci. Rep. sourcePartly supported

  The Results (Bioenergetics Parameters Related to Energy Production and Glycolysis; page unavailable) report evidence of a shift from oxidative phosphorylation toward glycolysis in late-onset Alzheimer’s disease fibroblasts, with elevated lactate relative to controls. The paper does not establish that this shift occurs specifically in APOE4 cells or that their glycolytic activity exceeds that of APOE3 cells. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

Elevated glycolysis has been viewed as a potential compensatory response to mitochondrial dysfunction after exposure to AD plasma, serving as an early indicator of cellular energy deficiency.

“Elevated glycolysis has been viewed as a potential compensatory response to mitochondrial dysfunction after exposure to AD plasma, serving as an early indicator of cellular energy deficiency [26,27].”

• cites [26] Jayasena, T., Poljak, A., Braidy, N., Smythe, G., Raftery, M., Hill, M., Brodaty, H., Trollor, J., Kochan, N., and Sachdev, P. (2015). Upregulation of Glycolytic Enzymes, Mitochondrial Dysfunction and Increased Cytotoxicity in Glial Cells Treated with Alzheimer’s Disease Plasma. PLoS ONE, 10. sourcePartly supported

  The Discussion (page unavailable) describes increased glycolysis after AD-plasma exposure as a possible compensation for compromised mitochondrial function, and the Results report impaired respiration alongside increased glycolysis in microglial cells. The paper does not identify elevated glycolysis as an early indicator of cellular energy deficiency; its separate reference to early events concerns mitochondrial dysfunction and altered energy metabolism in AD more broadly. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [27] Zhang, X., Alshakhshir, N., and Zhao, L. (2021). Glycolytic Metabolism, Brain Resilience, and Alzheimer’s Disease. Front. Neurosci., 15. sourceSupported

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

APOE4 N2A cells expressed higher levels of fission and fusion proteins than APOE3 N2A cells.

“MFN1, MFN2, OPA1, and FIS1 levels were decreased in the brains and neurons of AD patients and APOE4 carriers [37,38], whereas APOE4 N2A cells expressed higher levels of fission and fusion proteins than APOE3 N2A cells [33].”

• cites [33] Orr, 2019, Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function, J. Alzheimer’s Dis. sourceSupported

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

Early-stage metabolic changes have been detected in the brains of AD patients.

“early-stage metabolic changes have been detected in the brains of AD patients”

• Also stated in: § 1. Introduction · plain

  “alterations in the consumption of glucose as well as deficits in mitochondrial functions are hallmarks of AD [8]”

• cites [8] Yin, 2016, Energy Metabolism and Inflammation in Brain Aging and Alzheimer’s Disease, Free Radic. Biol. Med. sourceSupported

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

A recent study showed that APP KI mice display mitochondrial hypermetabolism before the onset of any pathology.

“This is further supported by a recent study showing that APP KI mice display mitochondrial hypermetabolism before the onset of any pathology.”

• cites [49] Naia, 2023, Mitochondrial Hypermetabolism Precedes Impaired Autophagy and Synaptic Disorganization in App Knock-in Alzheimer Mouse Models, Mol. Psychiatry sourcePartly supported

  The Introduction (page not provided) reports mitochondrial hypermetabolism in App knock-in mice before the establishment of Aβ pathology, and the Discussion describes it as preceding neuroinflammation and autophagic decline. The source does not establish that it occurs before *any* pathology; it describes altered energy metabolism as an early-stage pathological change. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

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

Earlier studies showed increased oxidative stress mechanisms and ROS production as well as upregulation of mitochondrial respiratory complexes in iPSC-derived neurons from sporadic AD patients, even in the absence of changes in Aβ or tau and p-tau levels.

“This aligns with earlier studies showing increased oxidative stress mechanisms and ROS production as well as upregulation of mitochondrial respiratory complexes in iPSC-derived neurons from sporadic AD patients, even in the absence of changes in Aβ or tau and p-tau levels [14].”

• cites [14] Birnbaum, 2018, Oxidative Stress and Altered Mitochondrial Protein Expression in the Absence of Amyloid-Beta and Tau Pathology in iPSC-Derived Neurons from Sporadic Alzheimer’s Disease Patients, Stem Cell Res. sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

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

Some studies indicated mitochondrial downregulation and decreased ATP production, contrary to the authors' findings of mitochondrial upregulation and enhanced ATP production in APOE4 cells.

“However, contrary to our findings of mitochondrial upregulation and enhanced ATP production in APOE4 cells, some studies indicated mitochondrial downregulation and decreased ATP production.”

• cites [29] Qi, 2021, ApoE4 Impairs Neuron-Astrocyte Coupling of Fatty Acid Metabolism, Cell Rep. sourceSupported
• cites [32] Chen, 2011, Apolipoprotein E4 Domain Interaction Mediates Detrimental Effects on Mitochondria and Is a Potential Therapeutic Target for Alzheimer Disease, J. Biol. Chem. sourcePartly supported

  The Results section (page not provided) reports lower levels of mitochondrial respiratory complexes and reduced respiratory capacity in apoE4-expressing cells, supporting mitochondrial downregulation. The paper does not report a direct measurement of decreased ATP production; its measurements of ATP synthase subunits do not establish that part of the claim. The citing authors’ contrasting findings are their own, not attributed to this source. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [33] Orr, 2019, Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function, J. Alzheimer’s Dis. sourceSupported

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

APOE4 expression in N2A cells decreased the enzymatic activity of complex IV.

“APOE4 expression in N2A cells decreased the enzymatic activity of complex IV [32].”

• cites [32] Chen, 2011, Apolipoprotein E4 Domain Interaction Mediates Detrimental Effects on Mitochondria and Is a Potential Therapeutic Target for Alzheimer Disease, J. Biol. Chem. sourceSupported

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

Neuron-specific proteolysis of APOE4, resulting in APOE4 fragments in the cytosol, caused toxic effects such as tau phosphorylation, alterations in cytoskeleton, and mitochondrial dysfunctions.

“Neuron-specific proteolysis of APOE4, resulting in APOE4 fragments in the cytosol, caused toxic effects such as tau phosphorylation, alterations in cytoskeleton, and mitochondrial dysfunctions [34,35].”

• cites [34] Mahley, R.W. (2023). Apolipoprotein E4 Targets Mitochondria and the Mitochondria-Associated Membrane Complex in Neuropathology, Including Alzheimer’s Disease. Curr. Opin. Neurobiol., 79. sourceNot checked — no full text of the source
• cites [35] Mahley, 2012, Apolipoprotein e Sets the Stage: Response to Injury Triggers Neuropathology, Neuron sourcePartly supported

  The sections on ApoE fragments entering the cytosol and on mitochondrial dysfunction link neuron-generated fragments to cytosolic entry and mitochondrial toxicity. The neurotoxic-effects section reports hyperphosphorylated tau in mice expressing truncated apoE4. However, the cytoskeletal-disruption findings in the neuronal-cytoskeleton section concern apoE4 exposure or expression, not specifically cytosolic apoE4 fragments, so that causal link is not established for every listed effect. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

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

Mitochondrial dysfunction is involved in early AD pathology.

“APOE4 carriers show mitochondrial dysfunction in brain areas associated with AD even before the onset of amyloid or tau pathology or cognitive changes, indicating that mitochondrial dysfunction is involved in early AD pathology [31].”

• cites [31] Valla, 2010, Reduced Posterior Cingulate Mitochondrial Activity in Expired Young Adult Carriers of the APOE Ε4 Allele, the Major Late-Onset Alzheimer’s Susceptibility Gene, J. Alzheimer’s Dis. sourcePartly supported

  The Abstract reports reduced mitochondrial cytochrome oxidase activity in young APOE ε4 carriers’ posterior cingulate cortex, generally without detectable amyloid or tau pathology. But it identifies one carrier who did have both, and says mitochondrial mechanisms *may contribute* to AD predisposition; it does not establish that dysfunction is involved in early AD pathology. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Classified as probably not a substantial claim.

If and how neuronal APOE mediates AD pathophysiology remains unclear.

“However, if and how neuronal APOE mediated AD pathophysiology remains unclear [7].”

• cites [7] Zhang, L., Xia, Y., and Gui, Y. (2023). Neuronal ApoE4 in Alzheimer’s Disease and Potential Therapeutic Targets. Front. Aging Neurosci., 15. sourcePartly supported

  The Abstract says that how neuronal ApoE4 mediates AD pathology remains unclear. But it also says neuronal ApoE4 induces Aβ and tau pathologies, so it does not present whether it contributes at all as unclear. The claim also broadens ApoE4 to neuronal APOE generally. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

May combine two claims.

The authors' results support the increase in glycolytic enzymes observed in frontal cortex lysate of AD patients and in glial cells after treatment with AD plasma.

“These results support the increase in glycolytic enzymes that has been observed in the frontal cortex lysate of AD patients as well as glial cells after treatment with AD plasma [25,26].”

• cites [25] Soucek, 2003, The Regulation of Glucose Metabolism by HIF-1 Mediates a Neuroprotective Response to Amyloid Beta Peptide, Neuron sourceNot checked — no full text of the source
• cites [26] Jayasena, T., Poljak, A., Braidy, N., Smythe, G., Raftery, M., Hill, M., Brodaty, H., Trollor, J., Kochan, N., and Sachdev, P. (2015). Upregulation of Glycolytic Enzymes, Mitochondrial Dysfunction and Increased Cytotoxicity in Glial Cells Treated with Alzheimer’s Disease Plasma. PLoS ONE, 10. sourceSupported

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

Upon increasing pathologies, the brain shifted to a state of hypometabolism.

“Upon increasing pathologies, the brain shifted to a state of hypometabolism [49].”

• cites [49] Naia, 2023, Mitochondrial Hypermetabolism Precedes Impaired Autophagy and Synaptic Disorganization in App Knock-in Alzheimer Mouse Models, Mol. Psychiatry sourceSupported

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

The proportion of inhibitory interneurons could be correlated with AD disease progression.

“However, it has been shown that inhibitory neurons express higher levels of APOE4, and the proportion of inhibitory interneurons could be correlated with AD disease progression [4,34,48]”

• cites [4] Blumenfeld, 2024, Cell Type-Specific Roles of APOE4 in Alzheimer Disease, Nat. Rev. Neurosci. sourcePartly supported

  The ‘APOE4 in Disease-associated neuronal subtypes’ section reports that AD progression was related to the proportion of neurons—especially inhibitory interneurons—expressing high levels of APOE. The claim omits that expression qualifier: the passage does not establish a correlation with the proportion of all inhibitory interneurons. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [34] Mahley, R.W. (2023). Apolipoprotein E4 Targets Mitochondria and the Mitochondria-Associated Membrane Complex in Neuropathology, Including Alzheimer’s Disease. Curr. Opin. Neurobiol., 79. sourceNot checked — no full text of the source
• cites [48] Nuriel, 2017, Neuronal Hyperactivity Due to Loss of Inhibitory Tone in APOE4 Mice Lacking Alzheimer’s Disease-like Pathology, Nat. Commun. sourceCould not verify

  The Results section reports reduced inhibitory synaptic currents in APOE4 mice, and the Discussion attributes reduced inhibitory tone to diminished responsiveness to GABAergic inputs. Neither passage addresses the proportion of inhibitory interneurons or its correlation with Alzheimer’s disease progression (searched: interneuron proportion and disease progression). (LLM, conf=0.76)

  Experimental — accuracy not yet measured

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

Sercel and colleagues wrote that it was long thought that mitochondrial diseases are linked to ATP deficiency, but that several studies now rather link mitochondrial and OXPHOS deficiency to hypermetabolism.

“In a recent comment, Sercel and colleagues wrote that it was long thought that mitochondrial diseases are linked to ATP deficiency, but that several studies now rather link mitochondrial and OXPHOS deficiency to hypermetabolism [50].”

• cites [50] Sercel, 2024, Hypermetabolism and Energetic Constraints in Mitochondrial Disorders, Nat. Metab. sourceSupported

May combine two claims.

The authors analyzed proteins involved in fusion and fission but did not observe any APOE-dependent effects in iN cells.

“Therefore, we analyzed proteins involved in fusion and fission, but did not observe any APOE-dependent effects in iN cells.”

May combine two claims.

ATP production and basal respiration of APOE-KO iN cells are comparable to APOE2 and strongly differ from APOE4 iN cells.

“ATP production, as well as basal respiration of APOE-KO iN cells were comparable to APOE2 and strongly differed from APOE4 iN cells”

• Also stated in: § Abstract · boosted

  “ATP production and basal respiration in APOE-KO iN cells strongly differed from APOE4 and more closely resembled APOE2 and APOE3 iN cells”

• AssumptionRests on an assumption: The iN cell cultures are pure neurons.

May combine two claims.

APOE4 iPSCs and iN cells displayed the highest glycoATP production, while no difference was observed between APOE2, -E3, and -KO.

“Both APOE4 iPSCs and iN cells displayed the highest glycoATP production, while no difference was observed between APOE2, -E3, and -KO (Figure 2E,I).”

May combine two claims.

Endogenously produced APOE4 increases mitochondrial energy metabolism in APOE-isogenic iN cells but not in the corresponding iPS cell line.

“We showed that endogenously produced APOE4 enhanced mitochondrial ATP production in APOE-isogenic iN cells but not in the corresponding iPS cell line.”

• Also stated in: § 1. Introduction · plain

  “In the present study, we show that endogenously produced APOE4 increases mitochondrial energy metabolism in pure APOE-isogenic human iPSC-derived neurons (iN cells) but not in the respective iPS cell line.”

• AssumptionRests on an assumption: The iN cell cultures are pure neurons.

May combine two claims.

Total ATP production in APOE4 iPSCs only significantly differed from APOE2 iPSCs, while APOE4 iN cells showed significantly higher total ATP production compared to all other iN cell lines.

“However, total ATP production in APOE4 iPSCs did only significantly differ from APOE2 iPSCs, while APOE4 iN cells showed significantly higher total ATP production compared to all other iN cell lines.”

May combine two claims.

APOE4 iN cells have the highest basal and maximal respiration compared to APOE-KO.

“We show that APOE regulates mitochondrial respiration and respiratory capacity in a genotype-dependent manner, with the highest basal and maximal respiration in APOE4 iN cells compared to APOE-KO and the highest spare respiratory capacity in APOE2.”

May combine two claims.

The authors' study showed enhancement of both oxidative and glycolytic metabolism.

“Our study showed enhancement of both oxidative as well as glycolytic metabolism.”

May combine two claims.

APOE-KO iN cells have a similar response as APOE2 and APOE3 but not as APOE4.

“When comparing APOE-KO cells to the other APOE cell lines, we observed that APOE-KO iN cells have a similar response as APOE2 and APOE3 but not as APOE4, concluding that APOE4 rather displays a gain-of-function than a loss-of-function mechanism.”

May combine two claims.

APOE4 iN cells showed the highest basal as well as maximal respiration.

“In contrast, APOE4 iN cells showed the highest basal as well as maximal respiration (Figure 4I,J)”

May combine two claims.

APOE2, -E3, and -E4 iN cells express APOE protein, with a small fraction being secreted.

“We demonstrated that APOE2, -E3, and -E4 iN cells express APOE protein, with a small fraction being secreted.”

• AssumptionRests on an assumption: The iN cell cultures are pure neurons.

May combine two claims.

In the authors' study, iN cells primarily used oxidative phosphorylation (OXPHOS) as their energy source, while iPSCs predominantly relied on glycolysis to meet their energy demands.

“As expected, the primary energy source for iN cells in our study was oxidative phosphorylation (OXPHOS), while iPSCs predominantly rely on glycolysis to meet their energy demands.”

May combine two claims.

APOE was detected in APOE2, -E3, and -E4 iPSCs and iN cells, while no APOE protein was present in APOE-KO cells.

“APOE was detected in APOE2, -E3, and -E4 iPSCs and iN cells (Figure 1E,F), while no APOE protein was present in APOE-KO cells.”

May combine two claims.

Mitochondrial fission marker FIS1 was decreased in APOE4 iPSCs compared to E2, but not changed in iN cells.

“Mitochondrial fission marker FIS1 was decreased in APOE4 iPSCs compared to E2 (Figure 3E), but not changed in iN cells (Figure 3I).”

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

APOE2 lowers AD risk, while APOE3 is risk neutral.

“In contrast, APOE2 is known to lower the AD risk, while APOE3 is defined as risk neutral.”

• Also stated in: § 1. Introduction · plain

  “While APOE3/3 is the most common genotype and is defined as risk neutral, the APOE2 allele is protective”

• cites [3] Michaelson, 2014, APOE Epsilon4: The Most Prevalent yet Understudied Risk Factor for Alzheimer’s Disease, Alzheimer’s Dement. J. Alzheimer’s Assoc. sourceNot checked — no full text of the source

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

qRT-PCR data were normalized to the housekeeping marker GAPDH.

“The data were normalized to the housekeeping marker GAPDH.”

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

Protein levels were normalized to the housekeeping proteins GAPDH or β-actin.

“protein levels were normalized to the housekeeping proteins GAPDH or β-actin.”

May combine two claims.

No differences were observed in marker expression and differentiation potential between the four APOE-isogenic lines.

“No differences were observed in marker expression and differentiation potential between the four APOE-isogenic lines (Figure 1B,C).”

Classified as probably not a substantial claim.

The use of isogenic lines allows the distinct analysis of APOE effects without bias caused by interpatient genetic variation.

“The use of isogenic lines thereby allows the distinct analysis of APOE effects without bias caused by interpatient genetic variation.”

May combine two claims.

APOE4 displays a gain-of-function rather than a loss-of-function mechanism.

“When comparing APOE-KO cells to the other APOE cell lines, we observed that APOE-KO iN cells have a similar response as APOE2 and APOE3 but not as APOE4, concluding that APOE4 rather displays a gain-of-function than a loss-of-function mechanism.”

• AssumptionRests on an assumption: APOE-KO cells provide a loss-of-function reference for comparing APOE genotypes.

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

FCCP titration was performed in earlier Seahorse experiments.

“FCCP titration was performed in earlier Seahorse experiments.”

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

These studies have primarily relied on animal models or cell lines, which may have different physiological and metabolic properties compared to human neurons, resulting in different outcomes.

“However, these studies have primarily relied on animal models or cell lines, which may have different physiological and metabolic properties compared to human neurons, resulting in different outcomes.”

Classified as probably not a substantial claim.

The time point of analysis seems to be a critical variable between the studies.

“Especially the time point of analysis seems to be a critical variable between the studies.”

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

Mitochondrial and glycolytic impairments had already been linked to AD before.

“Mitochondrial and glycolytic impairments had already been linked to AD before [30].”

• cites [30] Terada, 2020, In Vivo Mitochondrial and Glycolytic Impairments in Patients with Alzheimer Disease, Neurology sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

DAPI nuclei count was used for normalization of Seahorse data.

“The number of nuclei in each well was automatically analyzed by a macro written in Fiji and used for normalization of the Seahorse data”

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

Each Seahorse assay type was repeated three times for each cell line and included four background wells.

“Each assay type was repeated three times for each cell line and included four background wells for each assay.”

May combine two claims.

The authors observed the early hypermetabolism instead of hypometabolism because iPSC models represent very young cells and models of early disease or before disease onset.

“As iPSC models are considered to represent very young cells and are supposed to be models of early disease or even before disease onset, we observed the early hypermetabolism instead of hypometabolism.”

• AssumptionRests on an assumption: iPSC models represent very young cells and are models of early disease or even before disease onset.

May combine two claims.

qPCR confirmed that iPSCs were positive for OCT4, while iN cells show upregulation of MAP2 and βIII-tubulin (TUBB3) mRNA.

“qPCR confirmed that iPSCs were positive for OCT4, while iN cells show upregulation of MAP2 and βIII-tubulin (TUBB3) mRNA (Figure 1D).”

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

Neurons predominantly use OXPHOS for ATP production under basal conditions and switch to glycolysis when facing increased energy needs.

“Neurons predominantly use OXPHOS for ATP production under basal conditions and just switch to glycolysis when facing increased energy needs [24].”

• cites [24] Wei, 2023, Aerobic Glycolysis Is the Predominant Means of Glucose Metabolism in Neuronal Somata, Which Protects against Oxidative Damage, Nat. Neurosci. sourceNot checked — no full text of the source

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

The optimal cell density for each cell type was tested in prior Seahorse experiments.

“The optimal cell density for each cell type was tested in prior Seahorse experiments.”

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

Statistical analysis tested normal distribution using Shapiro-Wilk and Kolmogorov-Smirnov tests, identified outliers with ROUT, and used ANOVA or Kruskal-Wallis with appropriate post hoc tests.

“The normal distribution was tested using the Shapiro–Wilk normality test and the Kolmogorov–Smirnov test. Outliers were identified with the ROUT test (Q = 1%). Differences between more than two groups were either analyzed by one-way ANOVA for normally distributed data or by the Kruskal–Wallis test for not normally distributed data.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

The variations may be attributed to discrepancies across studies encompassing differences in cell types, cell species, and the time point of analysis.

“The variations may be attributed to discrepancies across studies encompassing differences in cell types, cell species, and the time point of analysis.”

May combine two claims.

APOE4 increased mitochondrial respiration in iN cells but not in iPSCs.

“Taken together, APOE4 increased mitochondrial respiration in iN cells but not in iPSCs.”

• AssumptionRests on an assumption: The iN cell cultures are pure neurons.
• AssumptionRests on an assumption: The observed differences in ATP production are not due to differences in mitochondrial mass or content between APOE genotypes.

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

APOE levels were normalized to total protein concentrations.

“Measured APOE levels were normalized to total protein concentrations (mg/mL)”

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

The study of Chemparathy and colleagues showed the protective function of APOE loss-of-variants in healthy individuals and AD patients.

“This is also consistent with the study of Chemparathy and colleagues showing the protective function of APOE loss-of-variants in healthy individuals and AD patients [43].”

• cites [43] Chemparathy, 2024, APOE Loss-of-Function Variants: Compatible with Longevity and Associated with Resistance to Alzheimer’s Disease Pathology, Neuron sourceNot checked — no full text of the source

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

One potential mechanism could be the upregulation of various biological processes and stress responses to compensate for OXPHOS deficits, ultimately resulting in hypermetabolism.

“One potential mechanism could be the upregulation of various biological processes and stress responses to compensate for OXPHOS deficits, ultimately resulting in hypermetabolism.”