The APOE-R136S mutation protects against APOE4-driven tau pathology, neurodegeneration, and neuroinflammation

APOE-R136S has severely reduced binding affinity to heparin.

“Notably, the APOE-R136S has severely reduced binding affinity to heparin, as the mutation occurs within the receptor-binding region of APOE36,45,58.”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourceSupported
• cites [45] Wardell, M. R., Brennan, S. O., Janus, E. D., Fraser, R. & Carrell, R. W. Apolipoprotein E2-Christchurch (136 Arg–Ser). New variant of human apolipoprotein E in a patient with type III hyperlipoproteinemia. J. Clin. Invest. 80, 483–490 (1987). sourceDisputed

  The Discussion (page unavailable) places residue 136 outside the recognized receptor-binding domain, contrary to the citing sentence’s explanation. It reports that APOE-R136S had the same heparin affinity as another APOE2 variant under denaturing conditions; it does not report severely reduced heparin affinity relative to normal APOE. (LLM, conf=0.84)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [58] Lalazar, A. et al. Site-specific mutagenesis of human apolipoprotein E. Receptor binding activity of variants with single amino acid substitutions. J. Biol. Chem. 263, 3542–3545 (1988). sourceNot checked — no full text of the source

Early p-Tau staining types 1 and 2 were enriched in PS19-E3 mice.

“The early p-Tau staining types 1 and 2 were enriched in PS19-E3 mice (Fig. 1h), as seen previously7.”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourceDisputed

  The paper’s discussion of p-tau staining patterns (section labeled Abstract; page unavailable) says types 1 and 2 were enriched in TEKO mice, not TE3 mice, and type 4 was enriched in TE4 mice. It describes these patterns in 9-month-old mice; it does not identify types 1 and 2 as early-age staining. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

APOE4 has increased binding affinity (up to two-fold) for heparin and HSPG over APOE3.

“By contrast, APOE4 has increased binding affinity (up to two-fold) for heparin and HSPG over APOE3 (refs. 32–35).”

• cites [32] Mahley, R. W. & Rall, S. C. Apolipoprotein E: far more than a lipid transport protein. Annu. Rev. Genom. Hum. Genet. 1, 507–537 (2000). sourceNot checked — no full text of the source
• cites [33] Ji, Z.-S., Pitas, R. E. & Mahley, R. W. Differential cellular accumulation/retention of apolipoprotein E mediated by cell surface heparan sulfate proteoglycans. Apolipoproteins E3 and E2 greater than E4. J. Biol. Chem. 273, 13452–13460 (1998). sourceDisputed

  In the ‘Metabolism of ¹²⁵I-apoE3- and ¹²⁵I-apoE4-enriched β-VLDL’ section (page unavailable), similar amounts of the two isoforms bound to wild-type CHO cells; the paper reports greater subsequent retention of apoE3. It does not report a two-fold greater apoE4 binding affinity for heparin or HSPG. The cell-binding experiment is not a direct affinity measurement, but its reported comparison runs contrary to the cited claim. (LLM, conf=0.78)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [34] Libeu, C. P. et al. New insights into the heparan sulfate proteoglycan-binding activity of apolipoprotein E. J. Biol. Chem. 276, 39138–39144 (2001). sourceNot checked — no full text of the source
• cites [35] Yamauchi, Y. et al. Role of the N- and C-Terminal domains in binding of apolipoprotein E isoforms to heparan sulfate and dermatan sulfate: a surface plasmon resonance study. Biochemistry 47, 6702–6710 (2008). sourcePartly supported

  The Results (page unavailable) report that apoE4 showed two- or three-fold higher binding to heparan sulfate (HS) and dermatan sulfate than apoE3. But this study does not establish the claimed increase in affinity for heparin or intact HSPG; it also says equilibrium affinity for HS did not differ much among the lipidated isoforms. The reported binding increase is not limited to two-fold. (LLM, conf=0.90)

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APOE4 is the strongest genetic risk factor for late-onset Alzheimer's disease.

“Apolipoprotein E4 (APOE4) is the strongest genetic risk factor for late-onset Alzheimer’s disease (LOAD)1–3.”

• cites [1] Huang, Y. & Mucke, L. Alzheimer mechanisms and therapeutic strategies. Cell 148, 1204–1222 (2012). sourceSupported
• cites [2] Mahley, R. W., Weisgraber, K. H. & Huang, Y. Apolipoprotein E4: a causative factor and therapeutic target in neuropathology, including Alzheimer’s disease. Proc. Natl Acad. Sci. USA 103, 5644–5651 (2006). sourcePartly supported

  The “ApoE and Neuropathology” section calls apoE4 the major known genetic risk factor for Alzheimer’s disease in many populations. It does not specify late-onset disease, and the citing sentence omits the population qualifier. (LLM, conf=0.83)

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• cites [3] Huang, Y. & Mahley, R. W. Apolipoprotein E: structure and function in lipid metabolism, neurobiology, and Alzheimer’s diseases. Neurobiol. Dis. 72PA, 3–12 (2014). sourceSupported

APOE4 exacerbates AD-related pathologies, including amyloid-beta plaques, Tau tangles, neurodegeneration and neuroinflammation.

“It exacerbates AD-related pathologies, including amyloid-beta (Aβ) plaques, Tau tangles, neurodegeneration and neuroinflammation4–16.”

• cites [4] Koutsodendris, N., Nelson, M. R., Rao, A. & Huang, Y. Apolipoprotein E and Alzheimer’s disease: findings, hypotheses, and potential mechanisms. Annu. Rev. Pathol. 17, 73–99 (2022). sourceNot checked — no full text of the source
• cites [5] Harris, F. M., Brecht, W. J., Xu, Q., Mahley, R. W. & Huang, Y. Increased tau phosphorylation in apolipoprotein E4 transgenic mice is associated with activation of extracellular signal-regulated kinase: modulation by zinc. J. Biol. Chem. 279, 44795–44801 (2004). sourceNot checked — no full text of the source
• cites [6] Wang, C. et al. Gain of toxic apolipoprotein E4 effects in human iPSC-derived neurons is ameliorated by a small-molecule structure corrector. Nat. Med. 24, 647–657 (2018). sourcePartly supported

  The Introduction associates apoE4 with increased amyloid plaques and tau tangles. The Discussion reports increased Aβ production, tau phosphorylation, and GABAergic neuron degeneration in apoE4 cultures. The passages do not address neuroinflammation, so that part of the claim is unsupported by this source. Page numbers were not available in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourcePartly supported

  The paper’s Abstract reports greater Aβ pathology with ApoE4 and, in P301S tau mice, higher tau levels, markedly greater brain atrophy, and more neuroinflammation. It does not establish that ApoE4 increases Tau tangles specifically; it reports tau redistribution and distinct phosphorylated-tau staining patterns instead. The mouse findings are also not direct evidence for every listed pathology in human AD. (LLM, conf=0.84)

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• cites [8] Brecht, W. J. et al. Neuron-specific apolipoprotein E4 proteolysis is associated with increased tau phosphorylation in brains of transgenic mice. J. Neurosci. 24, 2527–2534 (2004). sourcePartly supported

  The Introduction (page not provided) discusses amyloid-beta plaque formation as a proposed APOE4 mechanism and reports neurodegeneration and NFT-like inclusions associated with apoE fragments. The Results section on p-tau-containing inclusions (page not provided) finds more such inclusions in apoE4 than apoE3 mice. The paper does not establish that APOE4 exacerbates amyloid-beta plaques, and the passages found do not address neuroinflammation. (LLM, conf=0.88)

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• cites [9] Andrews-Zwilling, Y. et al. Apolipoprotein E4 causes age- and Tau-dependent impairment of GABAergic interneurons, leading to learning and memory deficits in mice. J. Neurosci. 30, 13707–13717 (2010). sourcePartly supported

  The Results section (page not provided) reports neurodegeneration and phosphorylated-Tau pathology in mice expressing an apoE4 fragment. The Introduction (page not provided) says apoE4 colocalizes with amyloid plaques and neurofibrillary tangles, but that does not establish that it exacerbates either. The passages do not report exacerbated neuroinflammation. (LLM, conf=0.88)

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• cites [10] Li, G. et al. GABAergic interneuron dysfunction impairs hippocampal neurogenesis in adult apolipoprotein E4 knockin mice. Cell Stem Cell 5, 634–645 (2009). sourcePartly supported

  The Results report increased tau phosphorylation and reduced neuronal survival in apoE4 knock-in mouse cultures; the Discussion links apoE4 neurotoxicity to neurodegeneration and describes a pathway to neurofibrillary tangles (page numbers unavailable). The passages do not establish that APOE4 exacerbates amyloid-beta plaques or neuroinflammation, and the study measures tau phosphorylation rather than tangle burden. (LLM, conf=0.88)

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• cites [11] Shi, Y. et al. Microglia drive APOE-dependent neurodegeneration in a tauopathy mouse model. J. Exp. Med. 216, 2546–2561 (2019). sourcePartly supported

  The Introduction says apoE4 significantly exacerbated neurodegeneration in P301S tauopathy mice. The Results link apoE to phosphorylated-tau pathology and show greater microglial activation in apoE4 mice than in apoE-deficient mice. The paper does not show that APOE4 exacerbates amyloid-β plaques, and its tau findings concern tau pathology rather than specifically demonstrating more tangles. (LLM, conf=0.88)

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• cites [12] Strittmatter, W. J. et al. Apolipoprotein E: high-avidity binding to beta-amyloid and increased frequency of type 4 allele in late-onset familial Alzheimer disease. Proc. Natl Acad. Sci. USA 90, 1977–1981 (1993). sourcePartly supported

  The Abstract reports that ApoE binds amyloid-beta and is present in senile plaques and neurofibrillary tangles; it also reports an association between APOE-e4 and late-onset familial Alzheimer disease. The passage labeled MATERIALS AND METHODS suggests a possible role for ApoE-E4 but does not establish that this isoform exacerbates those lesions. The cited passages do not support exacerbation of neurodegeneration or neuroinflammation. Page numbers are unavailable in our copy. (LLM, conf=0.88)

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• cites [13] Therriault, J. et al. APOEε4 potentiates the relationship between amyloid-β and tau pathologies. Mol. Psychiatry 26, 5977–5988 (2021). sourcePartly supported

  The Introduction links APOEε4 to increased amyloid-β burden and reports associations with inflammation and neurodegeneration in mouse models. The Results and Discussion support a stronger relationship between amyloid-β and tau pathology in APOEε4 carriers. The paper does not establish that APOEε4 exacerbates neuroinflammation or neurodegeneration generally; its statement about those outcomes is limited to an association reported in mouse models. Page numbers are unavailable in our copy. (LLM, conf=0.86)

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The E4 neuron culture had a lower fraction of GABA+ inhibitory neurons than the E3 neuron culture.

“As reported previously6, the E4 neuron culture had a lower fraction of GABA+ inhibitory neurons than the E3 neuron culture (Supplementary Fig. 2c,d).”

• cites [6] Wang, C. et al. Gain of toxic apolipoprotein E4 effects in human iPSC-derived neurons is ameliorated by a small-molecule structure corrector. Nat. Med. 24, 647–657 (2018). sourceSupported

The reported patient was protected from clinical effects of PSEN1-E280A, a highly penetrant EOAD mutation, for 28 years by the homozygous APOE3-R136S mutation.

“The reported patient was protected from the clinical effects of PSEN1-E280A, a highly penetrant mutation causing EOAD dementia41,42, for 28 years by the homozygous APOE3-R136S mutation36.”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourcePartly supported

  The case-report text (section labeled Abstract; page unavailable) says the PSEN1 E280A carrier had two copies of APOE3 Christchurch (R136S) and did not develop mild cognitive impairment until her seventies, nearly three decades after the typical onset age. It identifies APOE3ch homozygosity as the most likely genetic modifier, but omits her exact age and acknowledges that other factors could have contributed. Thus, neither precisely 28 years nor protection caused solely by APOE3-R136S is established. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [41] Quiroz, Y. T. et al. Association between amyloid and tau accumulation in young adults with autosomal dominant Alzheimer disease. JAMA Neurol. 75, 548–556 (2018). sourceSupported
• cites [42] Lemere, C. A. et al. The E280A presenilin 1 Alzheimer mutation produces increased Aβ 42 deposition and severe cerebellar pathology. Nat. Med. 2, 1146–1150 (1996). sourceNot checked — no full text of the source

Cell surface HSPGs mediate a large portion of neuronal uptake of Tau monomers and aggregates.

“Recent findings show that cell surface HSPGs mediate a large portion of neuronal uptake of Tau monomers and aggregates46,57.”

• cites [46] Rauch, J. N. et al. Tau internalization is regulated by 6-O sulfation on heparan sulfate proteoglycans (HSPGs). Sci. Rep. 8, 6382 (2018). sourcePartly supported

  The Results (Functional genomics to find modulators of tau uptake; page unavailable) report that knockdown of HSPG-related genes reduced monomer uptake by over 50% and also reduced oligomer uptake; the knockdowns reduced tau uptake in iPS-derived neurons. But the Results (Internalization of tau in CNS culture is regulated by quaternary structure; page unavailable) say intact fibrils were not efficiently internalized, so the unqualified reference to aggregates is broader than the evidence supports. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [57] Holmes, B. B. et al. Heparan sulfate proteoglycans mediate internalization and propagation of specific proteopathic seeds. Proc. Natl Acad. Sci. USA 110, E3138–E3147 (2013). sourcePartly supported

  The Discussion reports that HSPGs mediate tau aggregate uptake into neurons in vitro and in vivo. The Results distinguish fibrils from monomers, stating that tau repeat-domain fibrils, but not monomers, are readily internalized into neural precursor cells. This source therefore supports the aggregate portion of the claim, but not HSPG-mediated neuronal uptake of tau monomers. (LLM, conf=0.90)

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A major functional effect of the R136S mutation is disruption of APOE binding to anionic HSPGs on the cell surface.

“A major functional effect of the R136S mutation is disruption of its binding to anionic HSPGs on cell surface36,45.”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourcePartly supported

  The paper reports that APOE3 Christchurch (R136S) had the lowest heparin-binding ability among the APOE isoforms tested (Abstract; page unavailable). The Methods describe an in vitro heparin-column assay, not a measurement of binding to HSPGs on cell surfaces. Thus, reduced binding is supported, but disruption of cell-surface HSPG binding is not directly established. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [45] Wardell, M. R., Brennan, S. O., Janus, E. D., Fraser, R. & Carrell, R. W. Apolipoprotein E2-Christchurch (136 Arg–Ser). New variant of human apolipoprotein E in a patient with type III hyperlipoproteinemia. J. Clin. Invest. 80, 483–490 (1987). sourcePartly supported

  The Results identify the Arg136→Ser substitution, and the Discussion says it could alter receptor binding. But the Discussion does not establish disrupted binding to cell-surface HSPGs; its preliminary heparin-affinity comparison was with another APOE2 variant under denaturing conditions. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

E3 neurons had a significant reduction in p-Tau levels compared to E4 neurons.

“Western blotting analysis of cell lysates with PHF1 and AT8 antibodies revealed that the E3 neurons had a significant reduction in p-Tau levels compared to E4 neurons (Fig. 2a,c,d and Supplementary Fig. 3b,c), confirming our previous report6.”

• cites [6] Wang, C. et al. Gain of toxic apolipoprotein E4 effects in human iPSC-derived neurons is ameliorated by a small-molecule structure corrector. Nat. Med. 24, 647–657 (2018). sourceSupported

PS19-E4 mice displayed roughly two-fold higher AT8+ p-Tau coverage area in the hippocampus than PS19-E3 mice.

“PS19-E4 mice displayed roughly two-fold higher AT8+ p-Tau coverage area than PS19-E3 mice (Fig. 1b,c), as reported previously7,55.”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourcePartly supported

  The paper’s main text (Fig. 2b discussion; page unavailable in our copy) reports greater AT8-positive p-tau covered area in the hippocampus of 3-month-old TE4 mice. Extended Data Figure 4 also quantifies AT8-covered area for TE3 and TE4 mice, but the text in our copy does not give values establishing the claimed roughly two-fold difference. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [55] Koutsodendris, N. et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat. Aging 3, 275–296 (2023). sourcePartly supported

  The Results section ('Removal of APOE4 from neurons drastically reduces tau pathology'; page unavailable) reports that AT8 staining showed significantly more tau pathology throughout the hippocampus in PS19-fE4 mice than in PS19-fE3 mice. Our copy does not state that AT8-positive coverage area was roughly two-fold higher, so the magnitude is not verified. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The rare APOE3-R136S (APOE3-Christchurch) variant strongly protects against early-onset Alzheimer's disease.

“A recent discovery that a rare APOE variant, APOE3-R136S (APOE3-Christchurch)36, strongly protects against early-onset Alzheimer’s disease (EOAD)”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourcePartly supported

  The Abstract reports that a PSEN1 mutation carrier with two copies of APOE3-Christchurch developed mild cognitive impairment nearly three decades later than expected, supporting a protective association in this case. It does not establish that the variant generally strongly protects against early-onset Alzheimer’s disease: the authors identify it as the best candidate modifier in this subject, acknowledge other possible factors, and suggest that homozygosity may be required. (LLM, conf=0.88)

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The R136S mutation results in less APOE4 fragmentation.

“suggesting that the R136S mutation results in less APOE4 fragmentation6.”

• cites [6] Wang, C. et al. Gain of toxic apolipoprotein E4 effects in human iPSC-derived neurons is ameliorated by a small-molecule structure corrector. Nat. Med. 24, 647–657 (2018). sourceCould not verify

  The Results report less apoE fragmentation after gene editing converted apoE4 to apoE3, but do not identify that change as R136S. Searches for R136S and Arg136Ser found no passage testing or discussing that mutation’s effect on fragmentation. The cited paper therefore does not establish the specific claim. (LLM, conf=0.76)

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Microgliosis contributes to hippocampal degeneration.

“suggesting the contribution of microgliosis to hippocampal degeneration, as reported in previous studies7,55”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourceSupported
• cites [55] Koutsodendris, N. et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat. Aging 3, 275–296 (2023). sourceSupported

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

In 10-month-old PS19-E4 mice, AT8 percent coverage area was negatively correlated with hippocampal volume.

“In 10-month-old PS19-E4 mice, the AT8 (p-Tau) percent coverage area was negatively correlated with hippocampal volume (Fig. 4f), as shown previously7,55, indicating a deleterious role of p-Tau in hippocampal degeneration.”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourcePartly supported

  The paper reports that p-tau staining patterns in 9-month-old tau/ApoE mice correlated with brain atrophy (Abstract; page not specified). It does not report the claimed negative correlation between AT8 percent coverage and hippocampal volume specifically in 10-month-old PS19-E4 mice. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [55] Koutsodendris, N. et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat. Aging 3, 275–296 (2023). sourceSupported

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Astrocytosis contributes to hippocampal degeneration in PS19-E4 mice.

“suggesting the contribution of astrocytosis to hippocampal degeneration, as reported previously7”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourceSupported

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

PS19-E4 mice exhibited significantly reduced hippocampal volume compared to WT and PS19-E3 mice.

“PS19-E4 mice exhibited significantly reduced hippocampal volume compared to WT and PS19-E3 mice (Fig. 4a,b and Extended Data Fig. 2a), as reported previously7,55.”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourcePartly supported

  The Abstract reports significantly greater atrophy in 9-month-old P301S/E4 mice than in P301S/E3 mice and identifies the hippocampus as a primary site. However, Methods > Animals explicitly says the authors did not perform statistical comparisons between WT and the other mice, so the claimed significant difference from WT is not supported. (LLM, conf=0.90)

  Experimental — accuracy not yet measured
• cites [55] Koutsodendris, N. et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat. Aging 3, 275–296 (2023). sourcePartly supported

  The Results section, “Neurodegeneration is reduced after removal of neuronal APOE4” (page unavailable), reports greater neurodegeneration in PS19-fE4 than PS19-fE3 mice based on hippocampal and ventricular volumes. It does not report the claimed hippocampal-volume comparison with WT mice, so that part is unsupported by this source. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Some DE genes recently identified as markers of DAOs in AD mouse models were also upregulated in cluster 9 versus cluster 2, such as H2-D1, Il33 and C4b.

“Some DE genes recently identified as markers of DAOs in AD mouse models61 were also upregulated in cluster 9 versus cluster 2, such as those mediating the inflammatory process (H2-D1, Il33 and C4b)”

• cites [61] Kenigsbuch, M. et al. A shared disease-associated oligodendrocyte signature among multiple CNS pathologies. Nat. Neurosci. 25, 876–886 (2022). sourceSupported

A single copy of the R136S mutation is not sufficient to overcome the detrimental effects of APOE4 on neuronal Tau pathology.

“that a single copy of the R136S mutation is not sufficient to overcome the detrimental effects of APOE4 on neuronal Tau pathology”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourcePartly supported

  The paper’s main text (indexed under Abstract; page unavailable) reports that four PSEN1 mutation carriers with one APOE3 Christchurch (R136S) copy developed mild cognitive impairment at a mean age of 45, and postulates that two copies are required to postpone clinical onset. It does not establish that one copy fails to counteract APOE4 specifically, or assess neuronal tau pathology in those single-copy carriers. (LLM, conf=0.84)

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HSPGs are largely responsible for neuronal Tau uptake.

“Previous work showed that HSPGs are largely responsible for neuronal Tau uptake46–48,57.”

• cites [46] Rauch, J. N. et al. Tau internalization is regulated by 6-O sulfation on heparan sulfate proteoglycans (HSPGs). Sci. Rep. 8, 6382 (2018). sourcePartly supported

  The Results (‘Functional genomics to find modulators of tau uptake,’ page unavailable) report that knockdown of HSPG-biosynthesis genes reduced tau uptake in iPS-derived neurons. The Results (‘Cellular internalization of tau is effected by the presence of 6-O-sulfation,’ page unavailable) also report inhibited uptake in those neurons when heparin or heparan sulfate was added. These findings support an important role for HSPGs, but the text does not establish that they account for most neuronal tau uptake. (LLM, conf=0.78)

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• cites [47] Stopschinski, B. E. et al. Specific glycosaminoglycan chain length and sulfation patterns are required for cell uptake of tau vs. α-synuclein and β-amyloid aggregates. J. Biol. Chem. 293, 10826–10840 (2018). sourcePartly supported

  The GAG length/sulfation section reports that HSPGs mediate tau aggregate uptake, and Figure 8 shows reduced uptake after HSPG-pathway gene knockouts in HEK293T cells. The paper says the requirements still need evaluation in post-mitotic central nervous system neurons, so it does not establish the claim specifically for neuronal uptake. Page numbers were not supplied. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [48] Holmes, B. B. & Diamond, M. I. Prion-like properties of Tau protein: the importance of extracellular Tau as a therapeutic target. J. Biol. Chem. 289, 19855–19861 (2014). sourcePartly supported

  In “Understanding Cell Uptake” (page not available), the paper says HSPG binding initiates uptake of aggregated Tau seeds into neurons. It specifies that Tau monomers do not trigger uptake through this mechanism, and it does not establish that HSPGs account for most neuronal Tau uptake overall. The claim omits that limitation and overstates the pathway's share of uptake. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [57] Holmes, B. B. et al. Heparan sulfate proteoglycans mediate internalization and propagation of specific proteopathic seeds. Proc. Natl Acad. Sci. USA 110, E3138–E3147 (2013). sourcePartly supported

  The Discussion says HSPGs mediate binding and internalization of tau aggregates into neurons, and the primary-neuron experiment reports a 43% reduction in full-length tau fibril uptake after Ext1 knockdown. The source supports a major role for HSPGs in neuronal uptake of aggregated tau, but does not establish that they are largely responsible for uptake of Tau in general. (LLM, conf=0.87)

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The DAAs and DAMs have transcriptomic profiles similar to those previously reported in brains of patients with AD and mouse models.

“The DAAs and DAMs have transcriptomic profiles similar to those reported previously in brains of patients with AD and mouse models62,63.”

• cites [62] Habib, N. et al. Disease-associated astrocytes in Alzheimer’s disease and aging. Nat. Neurosci. 23, 701–706 (2020). sourcePartly supported

  The paper reports overlap between DAA genes and a previously described DAM signature, and Extended Data Figure 9 compares mouse DAA profiles with astrocytes from human AD and non-AD brains. The Methods state that the DAM signature came from prior literature; this paper does not establish that both DAA and DAM profiles resemble profiles previously reported in human AD brains. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [63] Keren-Shaul, H. et al. A unique microglia type associated with restricting development of Alzheimer’s disease. Cell 169, 1276–1290 (2017). sourcePartly supported

  The Results (page unavailable) identify a distinct DAM gene-expression profile in an AD mouse model. The Introduction (page unavailable) reports DAM-marker staining in human AD brains, but not a comparison with previously reported human transcriptomic profiles. The paper does not address DAAs, so it supports only the DAM portion of the claim. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

By substituting a positively charged arginine residue for the uncharged serine, the affinity of the receptor-binding domain of APOE-R136S for negatively charged HSPGs is greatly diminished.

“by substituting a positively charged arginine residue for the uncharged serine, the affinity of the receptor-binding domain of APOE-R136S for negatively charged HSPGs is greatly diminished36,45,58”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourcePartly supported

  The Abstract reports that ApoE3 Christchurch (R136S) had the lowest heparin-binding ability among the ApoE isoforms tested, supporting reduced binding. But the Methods describe the substitution as 136Arg→Ser—the reverse of the direction stated in the claim—and the experiment measured heparin binding, not affinity for HSPGs directly. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [45] Wardell, M. R., Brennan, S. O., Janus, E. D., Fraser, R. & Carrell, R. W. Apolipoprotein E2-Christchurch (136 Arg–Ser). New variant of human apolipoprotein E in a patient with type III hyperlipoproteinemia. J. Clin. Invest. 80, 483–490 (1987). sourcePartly supported

  The Results identify the Arg136→Ser substitution, and the Discussion says it could alter receptor binding. But the paper does not show that APOE-R136S has greatly diminished affinity for HSPGs. Its preliminary heparin experiment compares the variant with another APOE2 variant, not with unmutated APOE, and finds equal affinity under denaturing conditions (Discussion; page unavailable). (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [58] Lalazar, A. et al. Site-specific mutagenesis of human apolipoprotein E. Receptor binding activity of variants with single amino acid substitutions. J. Biol. Chem. 263, 3542–3545 (1988). sourceNot checked — no full text of the source

The original patient showed AD protection with the homozygous APOE3-R136S mutation.

“The original patient showed AD protection with the homozygous APOE3-R136S mutation36.”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourceSupported

APOE4 exacerbates these phenotypes in a PS19 tauopathy model.

“APOE4 exacerbates these phenotypes in a PS19 tauopathy model7,11,55.”

• cites [7] Shi, Y. et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 549, 523–527 (2017). sourceSupported
• cites [11] Shi, Y. et al. Microglia drive APOE-dependent neurodegeneration in a tauopathy mouse model. J. Exp. Med. 216, 2546–2561 (2019). sourceSupported
• cites [55] Koutsodendris, N. et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat. Aging 3, 275–296 (2023). sourceSupported

The top predicted off-target cut sites in coding regions by CHOPCHOP and COSMID were verified to be intact by Sanger sequencing.

“The top predicted off-target cut sites in coding regions by CHOPCHOP78 and COSMID79 were verified to be intact by Sanger sequencing.”

• cites [78] Labun, K. et al. Accurate analysis of genuine CRISPR editing events with ampliCan. Genome Res 29, 843–847 (2019). sourceCould not verify

  The Abstract describes ampliCan as a tool for analyzing high-throughput amplicon sequencing, and the Methods discuss filtering reads that may come from off-target amplification. Our copy does not report Sanger sequencing of predicted coding-region off-target sites or verify that those sites were intact (searched: Sanger, COSMID, and off-target-site verification). (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [79] Cradick, T. J., Qiu, P., Lee, C. M., Fine, E. J. & Bao, G. COSMID: a web-based tool for identifying and validating CRISPR/Cas off-target sites. Mol. Ther. Nucleic Acids 3, e214 (2014). sourceSupported

The most advanced type 4 p-Tau staining was enriched in PS19-E4 mice, with roughly 90% of sections showing type 3 or type 4 p-Tau staining.

“The most advanced type 4 p-Tau staining was enriched in PS19-E4 mice, with roughly 90% of sections analyzed showing type 3 or type 4 p-Tau staining (Fig. 1h).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

E4-R/S neurons did not show an effect on APOE protein levels.

“The E4-R/S neurons did not show such an effect on APOE protein levels (Fig. 2a,b and Supplementary Fig. 3a).”

No PHF1 p-Tau reduction was seen in E4-R/S neurons.

“whereas no such effect was seen in E4-R/S neurons (Fig. 2e,f).”

PS19-E4-S/S mice exhibited markedly reduced p-Tau accumulation, roughly to the levels in PS19-E3 mice.

“Remarkably, PS19-E4-S/S mice exhibited markedly reduced p-Tau accumulation, roughly to the levels in PS19-E3 mice (Fig. 1b,c).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The hiPSC lines expressed stem cell markers Nanog, OCT3/4, SOX2 and TRA-1-60.

“Additionally, they all expressed stem cell markers Nanog, OCT3/4, SOX2 and TRA-1-60 (Extended Data Fig. 3b).”

The number of AT8+ soma in the CA1 cell layer strongly correlated with the percent AT8 coverage area in the hippocampus.

“Notably, the number of AT8+ soma in the CA1 cell layer strongly correlated with the percent AT8 coverage area in the hippocampus (Supplementary Fig. 1b).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

E4-S/S neurons had a lower ratio of APOE fragment/full-length APOE than E4 neurons at both individual and combined hiPSC line levels.

“The E4-S/S neurons also had a lower ratio of APOE fragment/full-length APOE than E4 neurons at both the individual hiPSC line level and the combined hiPSC line level (Supplementary Fig. 2e,f)”

E4-S/S neurons showed an approximately 40% reduction in p-Tau levels compared to E4 neurons at both combined and individual hiPSC line levels.

“The E4-S/S neurons showed an approximately 40% reduction in p-Tau levels compared to E4 neurons at both the combined hiPSC line level (Fig. 2c,d) and the individual hiPSC line level (Supplementary Fig. 3b,c).”

APOE and GFAP double immunostaining confirmed high APOE expression in astrocytes of E4-S/S-KI mice, identical to that seen in astrocytes of the parental E4-KI mice.

“APOE and glial fibrillary acidic protein (GFAP) double immunostaining confirmed high APOE expression in astrocytes of E4-S/S-KI mice (Extended Data Fig. 1f), identical to that seen in astrocytes of the parental E4-KI mice (Extended Data Fig. 1f).”

Beading patterns in PHF1+ neurites, suggesting p-Tau aggregates and/or degenerating neurites, were least prevalent in E4-S/S neurons.

“We also observed some beading patterns in PHF1+ neurites, suggesting p-Tau aggregates and/or degenerating neurites, which were the least prevalent in E4-S/S neurons (Fig. 2e, arrowheads, and Fig. 2g).”

E4-R/S neurons did not show the same reduction of p-Tau levels as E4-S/S neurons.

“Notably, E4-R/S neurons did not show the same reduction of p-Tau levels (Fig. 2a,c,d and Supplementary Fig. 3b,c).”

Immunocytochemical staining with PHF1 revealed an approximately 35% reduction in p-Tau levels in E4-S/S neurons versus E4 neurons.

“Likewise, immunocytochemical staining with the PHF1 antibody also revealed an approximately 35% reduction in p-Tau levels in E4-S/S neurons versus E4 neurons (Fig. 2e,f)”

Both PS19-E4 and PS19-E4-R/S mice had significantly more AT8+ soma in the CA1 cell layer than PS19-E3 and PS19-E4-S/S mice.

“Both PS19-E4 and PS19-E4-R/S mice had significantly more AT8+ soma in CA1 than PS19-E3 and PS19-E4-S/S mice (Supplementary Fig. 1a).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Hippocampal lysates of PS19-E4 mice had significantly higher p-Tau levels than those of PS19-E3 mice at 10 months of age by AT8 and PHF1 western blotting.

“Hippocampal lysates of PS19-E4 mice had significantly higher p-Tau levels than those of PS19-E3 mice at 10 months of age, as determined by western blotting with AT8 and PHF1 antibodies (Fig. 1d–f).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

E4-S/S neurons had a five-fold increase in APOE protein levels compared to E4 neurons.

“The E4-S/S neurons had a five-fold increase in APOE protein levels compared to E4 neurons (Fig. 2a,b and Supplementary Fig. 3a).”

The E4-S/S neuron cultures showed a similar proportion of GABA+ inhibitory neurons to the E3 neuron cultures.

“The E4-S/S neuron cultures showed a similar proportion of GABA+ inhibitory neurons to the E3 neuron cultures (Supplementary Fig. 2c,d)”

The reduction in p-Tau accumulation seen in PS19-E4-S/S mice was not seen in PS19-E4-R/S mice.

“This reduction was not seen in PS19-E4-R/S mice (Fig. 1b,c)”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

In 10-month-old PS19-E4 mice, both GFAP and S100β coverage areas and cell numbers inversely correlated with hippocampal volume.

“both GFAP and S100β coverage areas (Extended Data Fig. 5c,g) and cell numbers (Fig. 5e,i) inversely correlated with hippocampal volume in 10-month-old PS19-E4 mice”

In 10-month-old PS19 mice, PS19-E4 mice exhibited significantly higher microglia immunoreactivity (both coverage area and cell number) via measurements of both Iba1 and CD68 than PS19-E3, PS19-E4-S/S and PS19-E4-R/S mice.

“The PS19-E4 mice exhibited significantly higher microglia immunoreactivity (both coverage area and cell number) via measurements of both markers than the PS19-E3, PS19-E4-S/S and PS19-E4-R/S mice”

Mild Tau pathology in PS19-E3 and PS19-E4-S/S mice positively correlated with astrocytosis.

“it positively correlated with astrocytosis (Supplementary Fig. 6e,f,i,j)”

The relationship between microgliosis and hippocampal degeneration in PS19-E3 and PS19-E4 mice was somewhat preserved.

“the relationship between microgliosis and hippocampal degeneration in PS19-E3 and PS19-E4 mice was somewhat preserved”

Similar results were obtained for quantifications of activated astrocyte (S100β+) coverage area and cell numbers.

“Similar results were obtained for quantifications of activated astrocyte (S100β+) coverage area and cell numbers (Fig. 5c,d and Extended Data Fig. 5b).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

In 10-month-old PS19-E4 and PS19-E4-R/S mice, both Iba1 and CD68 coverage areas and cell numbers inversely correlated with hippocampal volume.

“both Iba1 and CD68 coverage areas (Extended Data Fig. 5m,q) and cell numbers (Fig. 5q,u) inversely correlated with hippocampal volume in 10-month-old PS19-E4 and PS19-E4-R/S mice”

In PS19-E4-R/S mice, Tau pathology positively correlated with microgliosis.

“Tau pathology positively correlated with microgliosis (Supplementary Fig. 6o,p)”

Heparin treatment significantly reduced median fluorescence intensity in E4, E3 and E4-R/S neurons.

“Heparin treatment significantly reduced MFI in E4, E3 and E4-R/S neurons (Fig. 3b)”

EKO neurons showed a marked decrease in Tau-488 uptake versus E4 neurons, to roughly the level of E4-S/S neurons.

“The EKO neurons showed a marked decrease in Tau-488 uptake versus E4 neurons, to roughly the level of E4-S/S neurons (Fig. 3b).”

E3 neurons showed a trend of reduced Tau-488 uptake (~20%) compared to E4 neurons, not reaching significance.

“The E3 neurons also showed a trend of reduced Tau-488 uptake (~20%) compared to E4 neurons, although not reaching significance.”

Analysis of correlation between APOE4-R136S copy number (0, 1 or 2) and average hippocampal volume or average posterior lateral ventricle volume revealed a clear gene dose-dependent effect of R136S on protection of APOE4-promoted hippocampal degeneration.

“Analysis of correlation between the APOE4-R136S copy number (0, 1 or 2) and the average of hippocampal volume or the average of posterior lateral ventricle volume revealed a clear gene dose-dependent effect of the R136S mutation on the protection of APOE4-promoted hippocampal degeneration (Fig. 4d,e).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Only E4-S/S and EKO neurons had a significantly reduced fraction (~30%) of cells with internalized Tau-488 compared to E4 neurons.

“Only E4-S/S and EKO neurons had a significantly reduced fraction (~30%) of cells with internalized Tau-488, as compared to E4 neurons (Fig. 3c).”

PS19-E4-S/S mice had a trend toward lower astrocytosis compared to PS19-E4 mice at 6 months.

“although PS19-E4-S/S mice had a trend toward lower astrocytosis as compared to PS19-E4 mice”

PS19-E3 and PS19-E4-S/S mice showed a significant increase (~20%) in DG GC layer thickness over PS19-E4 mice.

“PS19-E3 and PS19-E4-S/S mice showed a significant increase (~20%) in DG GC layer thickness over PS19-E4 mice (Fig. 4k).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

EKO neurons treated with heparin showed a similarly small decrease, representing APOE-independent but HSPG-dependent Tau-488 uptake.

“The EKO neurons treated with heparin showed a similarly small decrease (Fig. 3b), which represents the APOE-independent but HSPG-dependent Tau-488 uptake.”

PS19-E4-R/S mice showed significantly higher Iba1+ and CD68+ cell numbers than PS19-E4-S/S mice.

“The PS19-E4-R/S mice showed significantly higher Iba1+ and CD68+ cell numbers than PS19-E4-S/S mice”

The effect of heparin treatment on the fraction of neurons with internalized Tau-488 was similar in E4 and E4-R/S neurons.

“The effect of heparin treatment on the fraction of neurons with internalized Tau-488 was similar in E4 and E4-R/S neurons (Fig. 3c).”

E4-S/S neurons exhibited an approximately 50% reduction in median fluorescence intensity compared to E4 neurons, indicating reduced Tau-488 uptake.

“The E4-S/S neurons exhibited an approximately 50% reduction in MFI compared to E4 neurons (Fig. 3b), indicating reduced Tau-488 uptake.”

PS19-E4-R/S mice showed a partial rescue of hippocampal atrophy toward PS19-E3 levels.

“We also observed a partial rescue of hippocampal atrophy in PS19-E4-R/S mice toward PS19-E3 levels (Fig. 4b).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Treatment with E4 neuron-conditioned medium (1:1 mixed with fresh medium) for 2 weeks increased p-Tau accumulation in both E3 and E4-S/S neurons to the level of E4 neurons.

“In fact, treatment with E4 neuron-conditioned medium (1:1 mixed with fresh medium) for 2 weeks increased p-Tau accumulation in both E3 and E4-S/S neurons to the level of E4 neurons (Fig. 3h,i).”

The relationships between p-Tau measures and hippocampal volume disappeared in PS19-E3 and PS19-E4-S/S mice.

“These relationships disappeared in PS19-E3 and PS19-E4-S/S mice (Fig. 4g,h and Supplementary Fig. 1d,e)”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

A significant correlation was observed between APOE4-R136S copy number and GFAP+ cell number.

“Notably, a significant correlation was observed between the APOE4-R136S copy number and GFAP+ cell number (Supplementary Fig. 5a).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

At 6 months of age, PS19 mice did not show the same differences in astrocytosis across APOE genotype groups.

“PS19 mice at 6 months of age did not show the same differences in astrocytosis across APOE genotype groups”

The number of AT8+ soma in the CA1 cell layer was negatively correlated to hippocampal volume in PS19-E4 mice.

“Similarly, the number of AT8+ soma in CA1 cell layer was negatively correlated to hippocampal volume in PS19-E4 mice (Supplementary Fig. 1c).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Mild Tau pathology in PS19-E3 and PS19-E4-S/S mice positively correlates with microgliosis.

“yet positively correlates with microgliosis (Supplementary Fig. 6g,h,k,l)”

E4 neurons treated with heparin reduced the fraction of neurons with internalized Tau-488 to levels seen in E4-S/S and EKO neurons without heparin treatment.

“It is again notable that E4 neurons treated with heparin reduced the fraction of neurons with internalized Tau-488 to levels seen in E4-S/S neurons and EKO neurons without heparin treatment.”

PS19-E4-R/S mice showed a non-significant increase (12%) in DG GC layer thickness over PS19-E4 mice.

“Again, PS19-E4-R/S mice showed a non-significant increase (12%) in DG GC layer thickness over PS19-E4 mice.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The inverse correlation between astrocytosis and hippocampal volume was mostly eliminated in PS19-E4-S/S mice.

“and PS19-E4-S/S mice (Fig. 5g,k and Extended Data Fig. 5e,i)”

The inverse correlation between astrocytosis and hippocampal volume was mostly eliminated in PS19-E3 mice.

“This correlation was mostly eliminated in PS19-E3 mice”

Mild microgliosis negatively correlated with hippocampal volume in PS19-E3 and PS19-E4-S/S mice.

“mild microgliosis negatively correlated with hippocampal volume in PS19-E3 and PS19-E4-S/S mice”

No significant difference was observed in hippocampal volume across APOE genotype groups of 6-month-old mice.

“No significant difference was observed in hippocampal volume across various APOE genotype groups of 6-month-old mice (Extended Data Fig. 2c,f).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Hippocampal atrophy of PS19-E4-S/S mice was reduced to similar levels to WT and PS19-E3 mice.

“Strikingly, hippocampal atrophy of PS19-E4-S/S mice was reduced to similar levels of those seen in WT and PS19-E3 mice (Fig. 4a,b).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The relationships between p-Tau measures and hippocampal volume were still present in PS19-E4-R/S mice.

“These relationships were still present in PS19-E4-R/S mice (Fig. 4i and Supplementary Fig. 1f)”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

E4 neurons treated with heparin exhibited reduction of median fluorescence intensity (~40%) to levels not significantly different from E4-S/S and EKO neurons without heparin treatment.

“Notably, E4 neurons treated with heparin exhibited reduction of MFI (~40%) to levels not significantly different from E4-S/S neurons and EKO neurons without heparin treatment.”

In PS19-E4 mice, Tau pathology had a trending correlation with astrocytosis.

“Tau pathology had a trending correlation with astrocytosis (Supplementary Fig. 6a,b)”

PS19-E4-S/S mice did show a trend toward lower microgliosis compared to PS19-E4 mice at 6 months.

“The PS19-E4-S/S mice did show a trend toward lower microgliosis as compared to PS19-E4 mice”

The relationship between astrocytosis and hippocampal volume was preserved in PS19-E4-R/S mice.

“However, this relationship was preserved in PS19-E4-R/S mice”

In 6-month-old PS19 mice, we did not observe the same differences in microgliosis across APOE genotype groups.

“In the 6-month-old PS19 mice, we did not observe the same differences in microgliosis across APOE genotype groups.”

PS19-E4-R/S mice had a partial rescue of lateral ventricle enlargement.

“Again, the PS19-E4-R/S mice had a partial rescue (Fig. 4c).”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

There was a significant correlation of the APOE4-R136S copy number to Iba1+ cell number.

“This was confirmed by significant correlation of the APOE4-R136S copy number to Iba1+ cell number”

In PS19-E4-R/S mice, Tau pathology positively, albeit weakly, correlated with astrocytosis.

“the Tau pathology positively, albeit weakly, correlated with astrocytosis (Supplementary Fig. 6m,n)”

Heparin treatment did not significantly alter endogenous p-Tau levels in E4-S/S neurons.

“Notably, heparin treatment did not significantly alter endogenous p-Tau levels in E4-S/S neurons (Fig. 3f).”

Microglia subclusters 2 and 11 were likely to contain more cells from PS19-E4-S/S mice than from PS19-E4 mice.

“microglia subclusters 2 and 11 were likely to contain more cells from PS19-E4-S/S mice than from PS19-E4 mice”

Excitatory neuron clusters 7 (CA2/3) and 28 had significantly higher odds of containing cells from either PS19-E4-S/S or PS19-E4-R/S mice than from PS19-E4 mice.

“Excitatory neuron clusters 7 (CA2/3) and 28 had significantly higher odds of containing cells from either PS19-E4-S/S or PS19-E4-R/S mice than from PS19-E4 mice”

Astrocyte subcluster 3 was enriched in PS19-E3 and PS19-E4-S/S mice, but not in PS19-E4-R/S mice, compared to PS19-E4 mice.

“astrocyte subcluster 3 was enriched in PS19-E3 and PS19-E4-S/S mice, but not in PS19-E4-R/S mice, compared to PS19-E4 mice”

No significant difference was observed in APOE expression in each cell cluster across various APOE genotypes.

“No significant difference was observed in APOE expression in each cell cluster across various APOE genotypes”

PCA analysis revealed that the disease-protective microglia subcluster 2 had a similar contribution to the measured pathologies as the four disease-protective neuronal clusters (1, 6, 7 and 28).

“PCA analysis revealed that the disease-protective microglia subcluster 2 had a similar contribution to the measured pathologies as the four disease-protective neuronal clusters (1, 6, 7 and 28)”

The R136S mutation eliminated neutral lipid accumulation in microglia in PS19-E4-S/S mice.

“the R136S mutation eliminated neutral lipid accumulation in microglia in PS19-E4-S/S mice”

Immunofluorescent staining using Nkain2 as a marker for DAA subcluster 5 and Id3 as a marker for DAA subcluster 7 confirmed a significant decrease in both DAA clusters in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice.

“Using Nkain2 as a marker for DAA subcluster 5 and Id3 as a marker for DAA subcluster 7, immunofluorescent staining confirmed a significant decrease in both DAA clusters in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice”

PCA analysis revealed that the disease-protective astrocyte subcluster 3 had a similar contribution to the measured pathologies as the four disease-protective neuronal clusters (1, 6, 7 and 28).

“Such PCA analysis revealed that the disease-protective astrocyte subcluster 3 had a similar contribution to the measured pathologies as the four disease-protective neuronal clusters (1, 6, 7 and 28)”

The top enriched DE pathways in these clusters were indicative of neuronal health and function, including axon guidance, synaptic integrity and long-term potentiation.

“the top enriched DE pathways in these clusters were indicative of neuronal health and function, including axon guidance, synaptic integrity and long-term potentiation”

The proportion of cells in excitatory neuron clusters 1, 6, 7 and 28 exhibited significant positive associations with hippocampal volume and negative associations with the coverage areas of p-Tau and gliosis.

“the proportion of cells in excitatory neuron clusters 1, 6, 7 and 28 exhibited significant positive associations with hippocampal volume and negative associations with the coverage areas of p-Tau and gliosis”

Microglia subcluster 8 was likely to contain fewer cells from PS19-E4-S/S mice than from PS19-E4 mice.

“microglia subcluster 8 was likely to contain fewer cells from PS19-E4-S/S mice than from PS19-E4 mice”

GFAP/BODIPY double staining revealed neutral lipid accumulation in astrocytes in PS19-E4 mice.

“GFAP/BODIPY double staining revealed neutral lipid accumulation in astrocytes in PS19-E4 mice”

Excitatory neuron cluster 1 (GC) and cluster 6 (CA2/3) had significantly higher odds of containing cells from PS19-E4-S/S mice than from PS19-E4 mice.

“excitatory neuron cluster 1 (GC) and cluster 6 (CA2/3) had significantly higher odds of containing cells from PS19-E4-S/S mice than from PS19-E4 mice”

Immunofluorescent staining using Gpnmb as a marker for DAM cluster 8 confirmed a significant decrease in this DAM cluster in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice.

“Using Gpnmb as a marker for DAM cluster 8, immunofluorescent staining confirmed a significant decrease in this DAM cluster in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice”

PS19-E4-R/S mice also had a significant decrease in microglia subcluster 8, although to a lesser extent than PS19-E4-S/S mice.

“PS19-E4-R/S mice also had a significant decrease in microglia subcluster 8, although to a lesser extent than PS19-E4-S/S mice”

Many of these highly upregulated DAO genes unique to cluster 9 were markedly downregulated in PS19-E4-S/S mice versus PS19-E4 mice.

“many of these highly upregulated DAO genes unique to cluster 9 were markedly downregulated in PS19-E4-S/S mice versus PS19-E4 mice”

Iba1/BODIPY double staining confirmed neutral lipid accumulation in microglia in PS19-E4 mice but not PS19-E3 mice.

“Iba1/BODIPY double staining confirmed neutral lipid accumulation in microglia in PS19-E4 mice but not PS19-E3 mice”

DAA subcluster 7 had enrichment of lipid and atherosclerosis pathway genes.

“DAA subcluster 7 had enrichment of lipid and atherosclerosis pathway genes”

Subcluster 7 was almost completely eliminated in PS19-E4-S/S mice.

“subcluster 7 was almost completely eliminated in PS19-E4-S/S mice”

Astrocyte subclusters 5 and 7 had lower odds of containing cells from PS19-E4-S/S mice than from PS19-E4 mice.

“astrocyte subclusters 5 and 7 had lower odds of containing cells from PS19-E4-S/S mice than from PS19-E4 mice”

Some DE pathways did differ based on the R136S gene dose.

“Notably, some DE pathways did differ based on the R136S gene dose.”

Immunofluorescent staining using Kirrel3 as a marker confirmed a significant decrease in the DAO cluster 9 in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice.

“Using Kirrel3 as a marker, immunofluorescent staining confirmed a significant decrease in the DAO cluster 9 in the hippocampus of PS19-E4-S/S mice versus PS19-E4 mice”

The APOE4-R136S mutation reduced lysosome size to levels similar to that of the PS19-E3 mice.

“the APOE4-R136S mutation reduced lysosome size to levels similar to that of the PS19-E3 mice”

The proportion of cells in microglia subclusters 2 and 11 exhibited positive associations with hippocampal volume and negative associations with the coverage areas of p-Tau and gliosis.

“the proportion of cells in microglia subclusters 2 and 11 exhibited positive associations with hippocampal volume and negative associations with the coverage areas of p-Tau and gliosis”

Astrocytes in PS19-E4 mice had enlarged Lamp1+ lysosomes as compared to those in PS19-E3 mice.

“astrocytes in PS19-E4 mice had enlarged Lamp1+ lysosomes as compared to those in PS19-E3 mice”

DAM subcluster 8 had enrichment of lipid and atherosclerosis pathway genes.

“We also observed enrichment of lipid and atherosclerosis pathway genes in DAM subcluster 8”

The DAO cluster 9 had many significantly upregulated genes uniquely identified in the current study, including Kirrel3, Neat1, Apod, Dgki, Fmn1, Pex5l, Sik3 and Grik2.

“the DAO cluster 9 had many significantly upregulated genes uniquely identified in the current study, including Kirrel3, Neat1, Apod, Dgki, Fmn1, Pex5l, Sik3 and Grik2”

DAM subcluster 8 had a similar contribution to the measured pathologies as the DAOs (cluster 9).

“Likewise, DAM subcluster 8 had a similar contribution to the measured pathologies as the DAOs (cluster 9)”

The R136S mutation eliminated neutral lipid accumulation in astrocytes in PS19-E4-S/S mice.

“the R136S mutation eliminated neutral lipid accumulation in astrocytes in PS19-E4-S/S mice”

The oligodendrocyte cluster 9 had lower odds of containing cells from PS19-E4-S/S and PS19-E4-R/S mice than from PS19-E4 mice.

“The oligodendrocyte cluster 9 had lower odds of containing cells from PS19-E4-S/S and PS19-E4-R/S mice than from PS19-E4 mice”

DAM subcluster 8 had many highly upregulated DE genes uniquely identified in the current study, including Igf1, Gpnmb, Mamdc2, Kif13 and Sash1.

“DAM subcluster 8 had many highly upregulated DE genes uniquely identified in the current study, including Igf1, Gpnmb, Mamdc2, Kif13 and Sash1”

DAA subcluster 7 had a similar contribution to the measured pathologies as the DAOs (cluster 9).

“Likewise, DAA subcluster 7 had a similar contribution to the measured pathologies as the DAOs (cluster 9)”

Astrocyte subclusters 3, 5 and 7 expressed high levels of APOE.

“All of these three astrocyte subclusters (3, 5 and 7) expressed high levels of APOE”

Astrocyte subclusters 5 and 7 had many highly upregulated DE genes uniquely identified in the current study.

“astrocyte subclusters 5 and 7 also had many highly upregulated DE genes uniquely identified in the current study”

These highly upregulated DE genes in the DAM subcluster 8 were heavily downregulated in PS19-E4-S/S mice versus PS19-E4 mice.

“these highly upregulated DE genes in the DAM subcluster 8 were heavily downregulated in PS19-E4-S/S mice versus PS19-E4 mice”

Many of these highly upregulated DE genes in DAA subclusters 5 and 7 were markedly downregulated in PS19-E4-S/S mice versus PS19-E4 mice.

“Many of these highly upregulated DE genes in DAA subclusters 5 and 7 were markedly downregulated in PS19-E4-S/S mice versus PS19-E4 mice”

PS19-E4-R/S mice also had a significant decrease in LOR of astrocyte subcluster 7, although to a lesser extent than PS19-E4-S/S mice.

“PS19-E4-R/S mice also had a significant decrease in LOR of astrocyte subcluster 7, although to a lesser extent than PS19-E4-S/S mice”

Disease-associated subpopulations correlated with the severity of Tau pathology, gliosis and neurodegeneration.

“These disease-associated subpopulations were enriched in APOE4-expressing tauopathy mice and correlated to the severity of Tau pathology, gliosis and neurodegeneration.”

The R136S mutation has a gene dose-dependent effect on decreasing disease-associated subpopulations of oligodendrocytes (DAOs), astrocytes (DAAs) and microglia (DAMs).

“There is a gene dose-dependent effect of the R136S mutation on increasing disease-protective neuronal, astrocytic and microglial subpopulations and decreasing disease-associated subpopulations of oligodendrocytes (DAOs), astrocytes (DAAs) and microglia (DAMs).”

The R136S mutation has a gene dose-dependent effect on increasing disease-protective neuronal, astrocytic and microglial subpopulations.

“There is a gene dose-dependent effect of the R136S mutation on increasing disease-protective neuronal, astrocytic and microglial subpopulations and decreasing disease-associated subpopulations of oligodendrocytes (DAOs), astrocytes (DAAs) and microglia (DAMs).”

Disease-associated subpopulations were enriched in APOE4-expressing tauopathy mice.

“These disease-associated subpopulations were enriched in APOE4-expressing tauopathy mice and correlated to the severity of Tau pathology, gliosis and neurodegeneration.”

Five stable, isogenic hiPSC lines (three E4-S/S clones and two E4-R/S clones) were karyotyped to ensure no chromosomal abnormalities.

“Five stable, isogenic hiPSC lines (three E4-S/S clones and two E4-R/S clones) were karyotyped to ensure no chromosomal abnormalities (Extended Data Fig. 3a).”

The R136S mutation may reduce APOE4's detrimental effect on GABAergic neurons.

“suggesting that the R136S mutation may reduce APOE4’s detrimental effect on GABAergic neurons.”

The five-fold APOE increase in E4-S/S neurons is likely an across-species difference because a similar phenotype was not observed in PS19-E4-S/S mouse hippocampal lysates.

“Because we did not observe a similar phenotype in PS19-E4-S/S mouse hippocampal lysates (Supplementary Fig. 4), this is likely an across-species difference, which warrants further study.”

R136S homozygosity is required to effectively protect against APOE4-driven p-Tau accumulation and progression of p-Tau staining patterns in the tauopathy mouse model.

“Together, these data indicate that the R136S homozygosity is required to effectively protect against APOE4-driven p-Tau accumulation and progression of p-Tau staining patterns in this tauopathy mouse model.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Only the homozygous R136S mutation protects against APOE4-induced p-Tau accumulation in human neurons.

“Taken together, these data illustrate that only the homozygous R136S mutation protects against APOE4-induced p-Tau accumulation in human neurons, in line with the in vivo observations in tauopathy mice (Fig. 1).”

• AssumptionRests on an assumption: The engineered R136S mutation in mouse and hiPSC APOE4 has the same functional consequence of defective HSPG binding as the human APOE3-R136S.

Protection of APOE4-driven p-Tau accumulation in the hippocampus requires the homozygous R136S mutation.

“This reduction was not seen in PS19-E4-R/S mice (Fig. 1b,c), suggesting that the protection of APOE4-driven p-Tau accumulation in the hippocampus requires the homozygous R136S mutation.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The neuronal cultures were validated negative for neural stem cells (SOX2), astrocytes (GFAP) and oligodendrocytes (Olig2).

“The neuronal cultures were also validated negative, via immunocytochemistry, for non-neuronal cell types, such as neural stem cells (SOX2), astrocytes (GFAP) and oligodendrocytes (Olig2) (Supplementary Fig. 2a,b).”

In the presence of severe Tau pathology and moderate microgliosis, both pathologies contribute to hippocampal degeneration.

“Thus, in the presence of severe Tau pathology and moderate microgliosis, both pathologies contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

The R136S mutation provides an intermediate level of protection against microgliosis in PS19-E4-R/S mice.

“suggesting an intermediate level of protection against microgliosis”

Astrocytosis might reach a plateau in PS19-E4 mice.

“These findings suggest that the astrocytosis might reach a plateau in PS19-E4 mice.”

Mild astrocytosis may not be sufficient to contribute to hippocampal degeneration.

“although the latter may not be sufficient to contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

The R136S mutation protects against APOE4-driven astrocytosis in a clear gene dose-dependent manner in this tauopathy model.

“Thus, the R136S mutation protects against APOE4-driven astrocytosis in a clear gene dose-dependent manner in this tauopathy model.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The receptor-binding-defective R136S mutation diminishes the ability of APOE to functionally contribute to Tau-488 uptake in E4-S/S neurons, mimicking EKO neurons.

“and (2) the receptor-binding-defective R136S mutation diminishes the ability of APOE to functionally contribute to Tau-488 uptake in E4-S/S neurons, mimicking EKO neurons.”

Mild Tau pathology can induce mild microgliosis.

“This suggests that mild Tau pathology can induce mild microgliosis.”

APOE-independent Tau-488 uptake by EKO neurons occurs at a similar level to E4-S/S neurons.

“This suggests that (1) the APOE-independent Tau-488 uptake by EKO neurons occurs at a similar level to E4-S/S neurons”

General microgliosis might reach a plateau in PS19-E4 mice.

“These data indicate that the general microgliosis might reach a plateau in PS19-E4 mice.”

Moderate astrocytosis is sufficient to contribute to hippocampal degeneration.

“suggesting that moderate astrocytosis is sufficient to contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

The lack of protection against p-Tau pathology in PS19-E4-R/S mice could be a contributing factor to neurodegeneration in these mice.

“suggesting that the lack of protection against p-Tau pathology in PS19-E4-R/S mice (Fig. 1c and Supplementary Fig. 1a) could be a contributing factor to neurodegeneration in these mice.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

Mild Tau pathology can induce mild astrocytosis.

“This suggests that mild Tau pathology can induce mild astrocytosis”

Milder astrocytosis in PS19-E3 and PS19-E4-S/S mice might not contribute to hippocampal degeneration.

“suggesting that milder astrocytosis in these mice might not contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

The E4-S/S protection against microgliosis may start at about or after 6 months of age.

“suggesting that the E4-S/S protection against microgliosis may start at about or after 6 months of age”

The defective HSPG binding of the R136S mutation may contribute to the reduced APOE4-driven Tau accumulation in human neurons.

“These data suggest that the defective HSPG binding of the R136S mutation may contribute to the reduced APOE4-driven Tau accumulation in human neurons.”

In the presence of severe Tau pathology and moderate astrocytosis, both pathologies contribute to hippocampal degeneration.

“Thus, in the presence of severe Tau pathology and moderate astrocytosis, both pathologies contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

In the presence of both severe Tau pathology and severe microgliosis, both pathologies contribute to hippocampal degeneration.

“Notably, in the presence of both severe Tau pathology and severe microgliosis, both pathologies contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

Milder Tau pathology in PS19-E3 and PS19-E4-S/S mice might not contribute to hippocampal degeneration.

“suggesting that milder Tau pathology in these mice might not contribute to hippocampal degeneration.”

• AssumptionRests on an assumption: The PS19 tauopathy mouse model crossed with human APOE4-KI mice recapitulates APOE4-driven AD tau pathology sufficiently to test protection by R136S.

The presence of exogenous APOE4, even with much higher endogenous APOE4-S/S levels, was sufficient to increase p-Tau accumulation in E4-S/S neurons to levels similar to E4 neurons.

“Thus, the presence of exogenous APOE4, even with much higher endogenous APOE4-S/S levels (Fig. 2a,b), was sufficient to increase p-Tau accumulation in E4-S/S neurons to levels similar to those seen in E4 neurons.”

• AssumptionRests on an assumption: E4 neuron-conditioned medium increases p-Tau in E3 and E4-S/S neurons through exogenous APOE4 rather than other secreted factors.

The protection of R136S mutation against APOE4-driven astrocytosis in the context of tauopathy starts at about or after 6 months of age.

“This suggests that the protection of R136S mutation against APOE4-driven astrocytosis in the context of tauopathy starts at about or after 6 months of age.”

The R136S mutation protects against APOE4-promoted microgliosis in the context of tauopathy in a gene dose-dependent manner.

“Together, these data indicate that the R136S mutation protects against APOE4-promoted microgliosis in the context of tauopathy in a gene dose-dependent manner.”

The homozygous R136S mutation protects against APOE4-induced p-Tau accumulation at least in part due to defective HSPG binding.

“Taken together, these data support the hypothesis that homozygous R136S mutation protects against APOE4-induced p-Tau accumulation at least in part due to defective HSPG binding.”

In the presence of both severe Tau pathology and severe astrocytosis, both pathologies contribute to hippocampal degeneration.

“Notably, in the presence of both severe Tau pathology and severe astrocytosis, both pathologies contribute to hippocampal degeneration”

• AssumptionRests on an assumption: Correlations between gliosis markers and hippocampal volume reflect a causal contribution of gliosis to hippocampal degeneration.

Even heterozygous R136S mutation provides protection against APOE4 effects in these clusters at the transcriptomic level.

“These suggest that even heterozygous R136S mutation provides protection against APOE4 effects in these clusters at the transcriptomic level.”

Cells in oligodendrocyte cluster 9 are disease-associated oligodendrocytes (DAOs).

“suggesting that cells in cluster 9 are disease-associated oligodendrocytes (DAOs)”

The R136S mutation protects against APOE4-induced dysregulation of lipid accumulation in microglia.

“suggesting that the R136S mutation protects against APOE4-induced dysregulation of lipid accumulation in microglia”

There are gene dose-related differential effects of APOE4-R136S mutation on these pathways in some neuronal clusters.

“This suggests gene dose-related differential effects of APOE4-R136S mutation on these pathways in some neuronal clusters.”

The R136S mutation markedly reverses the distinct transcriptomic profile of the DAOs.

“but also that the R136S mutation markedly reverses the distinct transcriptomic profile of the DAOs”

The DAO cluster 9 was diminished by the APOE4-R136S mutation.

“These data indicate not only that the DAO cluster 9 was diminished by the APOE4-R136S mutation”

The APOE4-R136S mutation protects against Tau uptake and p-Tau accumulation in an AD-relevant context using hiPSC-derived neurons.

“We also demonstrate the protection of the APOE4-R136S mutation against Tau uptake and p-Tau accumulation in an AD-relevant context using hiPSC-derived neurons”

The R136S mutation protects against APOE4-induced dysregulation of lipid accumulation in astrocytes.

“suggesting that the R136S mutation protects against APOE4-induced dysregulation of this process in astrocytes”

The R136S mutation reduces neuronal p-Tau accumulation partially by reducing APOE4-promoted Tau uptake due to the defective HSPG binding of APOE4-R136S.

“Our findings demonstrate that the R136S mutation reduces neuronal p-Tau accumulation partially by reducing APOE4-promoted Tau uptake due to the defective HSPG binding of APOE4-R136S.”

The heterozygous R136S mutation only partially protects against some of the detrimental effects of APOE4.

“Notably, the heterozygous R136S mutation only partially protects against some of the detrimental effects of APOE4”

APOE variants have related but distinct roles in different AD pathologies, which likely depend on cell type.

“This highlights the related but distinct roles of APOE variants in different AD pathologies, which likely depend on cell type.”

There is an intriguing uncoupling of APOE4-driven Tau pathology and gliosis as drivers of neurodegeneration in PS19-E4-R/S mice.

“We reveal an intriguing uncoupling of APOE4-driven Tau pathology and gliosis as drivers of neurodegeneration in PS19-E4-R/S mice.”

Healthier populations of astrocytes and microglia may mitigate the strong contribution of Tau pathology to neurodegeneration in the PS19-E4-R/S mice.

“Thus, healthier populations of astrocytes and microglia may mitigate the strong contribution of Tau pathology to neurodegeneration in the PS19-E4-R/S mice.”

This study does not address whether the APOE-R136S mutation also protects against Aβ-mediated neuroinflammatory and neurodegenerative effects.

“Thus, our study does not address the question as to whether the APOE-R136S mutation also protects against Aβ-mediated neuroinflammatory and neurodegenerative effects65–69.”

The APOE gene sequence in F1 breeders was verified to be unaltered except for the expected R136S mutation.

“The APOE gene sequence in F1 breeders was verified to be unaltered except for the expected R136S mutation.”

This study provides potential molecular and cellular mechanisms by which the APOE-R136S mutation confers protection as potential targets for therapeutic development against APOE4-related AD and tauopathies.

“This study also provides potential molecular and cellular mechanisms by which the APOE-R136S mutation confers protection as potential targets for therapeutic development against APOE4-related AD and tauopathies.”