Inhibition of amyloid-β plaque formation by α-synuclein

Journal name:
Nature Medicine
Year published:
Published online

Amyloid-β (Aβ) plaques and α-synuclein (α-syn)-rich Lewy bodies are the major neuropathological hallmarks of Alzheimer's disease (AD) and Parkinson's disease, respectively. An overlap of pathologies is found in most individuals with dementia with Lewy bodies (DLB)1 and in more than 50% of AD cases2. Their brains display substantial α-syn accumulation not only in Lewy bodies, but also in dystrophic neurites decorating Aβ plaques2, 3, 4. Several studies report binding and coaggregation of Aβ and α-syn5, 6, 7, yet the precise role of α-syn in amyloid plaque formation remains elusive. Here we performed intracerebral injections of α-syn–containing preparations into amyloid precursor protein (APP) transgenic mice (expressing APP695KM670/671NL and PSEN1L166P under the control of the neuron-specific Thy-1 promoter; referred to here as 'APPPS1'). Unexpectedly, α-syn failed to cross-seed Aβ plaques in vivo, but rather it inhibited plaque formation in APPPS1 mice coexpressing SNCAA30P (referred to here as 'APPPS1 × [A30P]aSYN' double-transgenic mice). This was accompanied by increased Aβ levels in cerebrospinal fluid despite unchanged overall Aβ levels. Notably, the seeding activity of Aβ-containing brain homogenates was considerably reduced by α-syn, and Aβ deposition was suppressed in grafted tissue from [A30P]aSYN transgenic mice. Thus, we conclude that an interaction between Aβ and α-syn leads to inhibition of Aβ deposition and to reduced plaque formation.

At a glance


  1. [alpha]-syn-containing preparations do not induce A[beta] plaque formation in 6-week-old APPPS1 [times] Thy1-GFP transgenic mice.
    Figure 1: α-syn–containing preparations do not induce Aβ plaque formation in 6-week-old APPPS1 × Thy1-GFP transgenic mice.

    (a) Immunostaining against Aβ with antibody 3552 (red) of hippocampi from male APPPS1 × Thy1-GFP mice with neuronal Thy1-GFP expression (green) euthanized 10 weeks after injections. Representative images of Aβ and GFP immunoreactivity from uninjected mice (n = 4) and mice injected with WT brain homogenate (n = 4), APPPS1 brain homogenate (n = 4) or [A30P]aSYN brain homogenate (n = 4). White arrowheads and the inset indicate the presence of Aβ deposits. (b) Representative image of Aβ and GFP immunoreactivity in an APPPS1 brain homogenate–injected Thy1-GFP animal (n = 5). (c) Immunoblot analysis of brain homogenates from WT, APPPS1 and [A30P]aSYN mice that were used for injections. (d) Quantification of hippocampal Aβ load. Data are presented as mean ± s.e.m., *P < 0.05 by Kruskal-Wallis test. (e) Immunostaining against Aβ (red) from hippocampi of APPPS1 × Thy1-GFP transgenic animals injected with brainstem homogenate from a symptomatic 21-month-old [A30P]aSYN transgenic mouse (n = 5), brain homogenate from a DLB patient with confirmed LB pathology (n = 5), PFFs of NAC peptide (n = 5) and recombinant α-syn PFFs (n = 6). (f) Immunostaining of pathological α-syn inclusions with phospho-Ser129 antibody (red) in uninjected (n = 4) and α-syn PFF–injected (n = 6) APPPS1 × Thy1-GFP transgenic mice. Scale bars in a,b,e, 300 μm; in a (inset), 80 μm; lower magnification in f (left and second from right), 100 μm; higher magnification in f (right and second from left), 50 μm.

  2. Reduced hippocampal plaque load in APPPS1 [times] [A30P]aSYN transgenic mice.
    Figure 2: Reduced hippocampal plaque load in APPPS1 × [A30P]aSYN transgenic mice.

    (a) Representative images of immunofluorescence staining of Aβ plaques (red) and neuronal nuclei (NeuN, green) from 4-month-old female APPPS1 transgenic (n = 9) or APPPS1 × [A30P]aSYN transgenic littermates (n = 6). (b) Quantification of the hippocampal Aβ load as Aβ-positive area fraction. Data are presented as mean ± s.e.m., *P < 0.05 by two-tailed Mann-Whitney test. (c,d) Representative images (c) and quantification (d) of thiazin red (TR) staining of dense-core plaques in APPPS1 (n = 9) and APPPS1 × [A30P]aSYN (n = 6) transgenic animals. Data are presented as mean ± s.e.m., *P < 0.05 by two-tailed Mann-Whitney test. (e,f) Aβ immunoassay for Aβ-40 (e) and Aβ-42 (f) in CSF samples from 4-month-old female WT (n = 6), [A30P]aSYN (n = 8), APPPS1 (n = 10) and APPPS1 × [A30P]aSYN (n = 5) transgenic mice. Data are presented as mean ± s.e.m., *P < 0.05, **P < 0.01 by two-tailed Mann-Whitney test. Scale bars in a,c, 300 μm.

  3. A[beta] seeding is decreased by [alpha]-syn.
    Figure 3: Aβ seeding is decreased by α-syn.

    (a) Immunofluorescence staining of Aβ plaques (red) in hippocampi of male APPPS1 (left) or APPPS1 × [A30P]aSYN (right) transgenic host animals injected with brain homogenates from aged APPPS1 transgenic mice. (b) Quantification of Aβ load in APPPS1 and APPPS1 × [A30P]aSYN transgenic host animals from a (n = 4; data are presented as mean ± s.e.m., two-tailed Mann-Whitney test, *P < 0.05). (c) APPPS1 transgenic animals injected with APPPS1 transgenic brain homogenates mixed with either WT (left, n = 5), [A30P]aSYN transgenic (middle, n = 5) or α-syn–immunodepleted [A30P]aSYN (right, n = 4) brain homogenate. (d) Aβ load in hippocampi injected with brain homogenate mixture from APPPS1, [A30P]aSYN transgenic mice or α-syn–immunodepleted brain homogenate mixture from APPPS1 and [A30P]aSYN transgenic mice. Data are presented as mean ± s.e.m., N.S., not significant (P > 0.05), *P < 0.05 by Dunn's multiple comparisons test after Kruskal-Wallis test. (e) Immunoblot analysis of Aβ and α-syn from injected brain homogenates. (f) Representative images of APPPS1 transgenic animals injected with brain homogenates from the frontal association cortex of either an individual with AD (with no Lewy bodies or neurites; left) or an individual with DLB with mixed pathologies (amyloid plaques, Lewy bodies and neurites; right), n = 5 animals injected per group. (g) Quantification of hippocampal Aβ load in injected animals (n = 5; data are presented as mean ± s.e.m., two-tailed Mann-Whitney test, **P < 0.01). (h) Immunoblot analysis of Aβ in human brain homogenates used for injections. Scale bars in a,c,f, 350 μm. Ctrl, healthy control subject. White arrowheads indicate the presence of Aβ deposits.

  4. Suppressed A[beta] deposition and reduced A[beta]-42 fibril formation in the presence of [alpha]-syn.
    Figure 4: Suppressed Aβ deposition and reduced Aβ-42 fibril formation in the presence of α-syn.

    (a,b) Representative immunostaining images of WT (n = 20) (a) and [A30P]aSYN transgenic (n = 10) (b) cortical grafts in female APPPS1 × Thy1-GFP host tissue. Left, APP (red) and GFP (green) labeling of host and grafted tissue, respectively. Human α-syn (blue) in [A30P]aSYN transgenic graft. Middle, Aβ-specific immunostaining (red), DAPI (blue) and GFP (green). Right, Iba1 (red), NeuN (blue) and GFP (green). The dashed white lines mark the border of the graft and the white arrowheads indicate the presence of Aβ deposits. Scale bars, 100 μm. (c) Fraction of WT (n = 20) or [A30P]aSYN transgenic (n = 10) grafts positive or negative for amyloid plaques. ***P < 0.001 by two-tailed Fisher's exact test. (d) Number of plaques per graft within WT or [A30P]aSYN transgenic grafts. Data are presented as mean ± s.e.m., ***P < 0.001 by two-tailed Mann-Whitney test. (e,f) Analysis of Aβ fibril formation in vitro in the presence of WT α-syn or α-synA30P. (e) In vitro ThT assay of Aβ-42 fibril formation. Blank subtracted values were normalized against Aβ-42 ThT fluorescence after 24 h agitation of the respective aggregation experiment. Data points represent mean ± s.e.m. from three independent aggregation experiments. (f) As a control, α-syn was added at the end of the Aβ aggregation phase. (g) Ultrastructural analysis of in vitro Aβ-42 fibril formation in the presence of WT α-syn or α-synA30P. Scale bar, 100 nm.


  1. McKeith, I. et al. Dementia with Lewy bodies. Lancet Neurol. 3, 1928 (2004).
  2. Hamilton, R.L. Lewy bodies in Alzheimer's disease: a neuropathological review of 145 cases using α-synuclein immunohistochemistry. Brain Pathol. 10, 378384 (2000).
  3. Takeda, A. et al. Abnormal accumulation of NACP/α-synuclein in neurodegenerative disorders. Am. J. Pathol. 152, 367372 (1998).
  4. McKeith, I.G. et al. Diagnosis and management of dementia with Lewy bodies: third report of the DLB Consortium. Neurology 65, 18631872 (2005).
  5. Jensen, P.H. et al. Binding of Aβ to α- and β-synucleins: identification of segments in α-synuclein/NAC precursor that bind Aβ and NAC. Biochem. J. 323, 539546 (1997).
  6. Jensen, P.H., Sorensen, E.S., Petersen, T.E., Gliemann, J. & Rasmussen, L.K. Residues in the synuclein consensus motif of the α-synuclein fragment, NAC, participate in transglutaminase-catalysed cross-linking to Alzheimer-disease amyloid βA4 peptide. Biochem. J. 310, 9194 (1995).
  7. Tsigelny, I.F. et al. Mechanisms of hybrid oligomer formation in the pathogenesis of combined Alzheimer's and Parkinson's diseases. PLoS ONE 3, e3135 (2008).
  8. Uéda, K. et al. Molecular cloning of cDNA encoding an unrecognized component of amyloid in Alzheimer disease. Proc. Natl. Acad. Sci. USA 90, 1128211286 (1993).
  9. Lashuel, H.A., Overk, C.R., Oueslati, A. & Masliah, E. The many faces of α-synuclein: from structure and toxicity to therapeutic target. Nat. Rev. Neurosci. 14, 3848 (2013).
  10. Kane, M.D. et al. Evidence for seeding of β-amyloid by intracerebral infusion of Alzheimer brain extracts in β-amyloid precursor protein–transgenic mice. J. Neurosci. 20, 36063611 (2000).
  11. Meyer-Luehmann, M. et al. Exogenous induction of cerebral β-amyloidogenesis is governed by agent and host. Science 313, 17811784 (2006).
  12. Luk, K.C. et al. Pathological α-synuclein transmission initiates Parkinson-like neurodegeneration in nontransgenic mice. Science 338, 949953 (2012).
  13. Luk, K.C. et al. Intracerebral inoculation of pathological α-synuclein initiates a rapidly progressive neurodegenerative α-synucleinopathy in mice. J. Exp. Med. 209, 975986 (2012).
  14. Giasson, B.I. et al. Initiation and synergistic fibrillization of tau and α-synuclein. Science 300, 636640 (2003).
  15. Waxman, E.A. & Giasson, B.I. Induction of intracellular tau aggregation is promoted by α-synuclein seeds and provides novel insights into the hyperphosphorylation of tau. J. Neurosci. 31, 76047618 (2011).
  16. Guo, J.L. et al. Distinct α-synuclein strains differentially promote tau inclusions in neurons. Cell 154, 103117 (2013).
  17. Radde, R. et al. Aβ42-driven cerebral amyloidosis in transgenic mice reveals early and robust pathology. EMBO Rep. 7, 940946 (2006).
  18. Feng, G. et al. Imaging neuronal subsets in transgenic mice expressing multiple spectral variants of GFP. Neuron 28, 4151 (2000).
  19. Neumann, M. et al. Misfolded proteinase K-resistant hyperphosphorylated α-synuclein in aged transgenic mice with locomotor deterioration and in human α-synucleinopathies. J. Clin. Invest. 110, 14291439 (2002).
  20. Volpicelli-Daley, L.A. et al. Exogenous α-synuclein fibrils induce Lewy body pathology leading to synaptic dysfunction and neuron death. Neuron 72, 5771 (2011).
  21. Sturchler-Pierrat, C. et al. Two amyloid precursor protein transgenic mouse models with Alzheimer disease-like pathology. Proc. Natl. Acad. Sci. USA 94, 1328713292 (1997).
  22. McCarter, J.F. et al. Clustering of plaques contributes to plaque growth in a mouse model of Alzheimer's disease. Acta Neuropathol. 126, 179188 (2013).
  23. Heyman, A. et al. Comparison of Lewy body variant of Alzheimer's disease with pure Alzheimer's disease: consortium to establish a registry for Alzheimer's disease, part XIX. Neurology 52, 18391844 (1999).
  24. Kallhoff, V., Peethumnongsin, E. & Zheng, H. Lack of α-synuclein increases amyloid plaque accumulation in a transgenic mouse model of Alzheimer's disease. Mol. Neurodegener. 2, 6 (2007).
  25. Strozyk, D., Blennow, K., White, L.R. & Launer, L.J. CSF Aβ 42 levels correlate with amyloid-neuropathology in a population-based autopsy study. Neurology 60, 652656 (2003).
  26. Sunderland, T. et al. Decreased β-amyloid1–42 and increased tau levels in cerebrospinal fluid of patients with Alzheimer disease. J. Am. Med. Assoc. 289, 20942103 (2003).
  27. Fagan, A.M. et al. Inverse relation between in vivo amyloid imaging load and cerebrospinal fluid Aβ42 in humans. Ann. Neurol. 59, 512519 (2006).
  28. Kawarabayashi, T. et al. Age-dependent changes in brain, CSF and plasma amyloid (β) protein in the Tg2576 transgenic mouse model of Alzheimer's disease. J. Neurosci. 21, 372381 (2001).
  29. Maia, L.F. et al. Changes in amyloid-β and tau in the cerebrospinal fluid of transgenic mice overexpressing amyloid precursor protein. Sci. Transl. Med. 5, 194re2 (2013).
  30. Meyer-Luehmann, M. et al. Extracellular amyloid formation and associated pathology in neural grafts. Nat. Neurosci. 6, 370377 (2003).
  31. Brown, D.F. et al. Neocortical synapse density and Braak stage in the Lewy body variant of Alzheimer disease: a comparison with classic Alzheimer disease and normal aging. J. Neuropathol. Exp. Neurol. 57, 955960 (1998).
  32. Samuel, W., Alford, M., Hofstetter, C.R. & Hansen, L. Dementia with Lewy bodies versus pure Alzheimer disease: differences in cognition, neuropathology, cholinergic dysfunction, and synapse density. J. Neuropathol. Exp. Neurol. 56, 499508 (1997).
  33. Hansen, L.A., Daniel, S.E., Wilcock, G.K. & Love, S. Frontal cortical synaptophysin in Lewy body diseases: relation to Alzheimer's disease and dementia. J. Neurol. Neurosurg. Psychiatry 64, 653656 (1998).
  34. Olichney, J.M. et al. Cognitive decline is faster in Lewy body variant than in Alzheimer's disease. Neurology 51, 351357 (1998).
  35. Bibl, M. et al. CSF amyloid-β-peptides in Alzheimer's disease, dementia with Lewy bodies and Parkinson's disease dementia. Brain 129, 11771187 (2006).
  36. Eisenberg, D. & Jucker, M. The amyloid state of proteins in human diseases. Cell 148, 11881203 (2012).
  37. Compta, Y., Revesz, T. & Lees, A.J. The more cortical amyloid-β, the more postural instability in Parkinson's disease: more grist to the mill for a link between walking, falling, and remembering? Mov. Disord. 28, 263264 (2013).
  38. Kahle, P.J. et al. Subcellular localization of wild-type and Parkinson's disease–associated mutant α-synuclein in human and transgenic mouse brain. J. Neurosci. 20, 63656373 (2000).
  39. Yamasaki, A. et al. The GxGD motif of presenilin contributes to catalytic function and substrate identification of γ-secretase. J. Neurosci. 26, 38213828 (2006).
  40. Fujiwara, H. et al. α-Synuclein is phosphorylated in synucleinopathy lesions. Nat. Cell Biol. 4, 160164 (2002).
  41. Paxinos, G. & Franklin, K.B.J. The Mouse Brain in Stereotaxic Coordinates 2nd edn. (Academic Press, 2001).
  42. DeMattos, R.B. et al. Plaque-associated disruption of CSF and plasma amyloid-beta (Aβ) equilibrium in a mouse model of Alzheimer's disease. J. Neurochem. 81, 229236 (2002).
  43. Page, R.M. et al. Loss of PAFAH1B2 reduces amyloid-β generation by promoting the degradation of amyloid precursor protein C-terminal fragments. J. Neurosci. 32, 1820418214 (2012).

Download references

Author information


  1. Adolf Butenandt Institute, Department of Biochemistry, Ludwig-Maximilians University, Munich, Germany.

    • Teresa Bachhuber,
    • Joanna F McCarter,
    • Claudia Abou-Ajram &
    • Melanie Meyer-Luehmann
  2. Neurocenter, Department of Neurology, University of Freiburg, Freiburg, Germany.

    • Natalie Katzmarski,
    • Desiree Loreth &
    • Melanie Meyer-Luehmann
  3. Faculty of Biology, University of Freiburg, Freiburg, Germany.

    • Natalie Katzmarski
  4. German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.

    • Sabina Tahirovic,
    • Harald Steiner &
    • Christian Haass
  5. Department of Metabolic Biochemistry, Ludwig-Maximilians University, Munich, Germany.

    • Frits Kamp,
    • Brigitte Nuscher,
    • Harald Steiner &
    • Christian Haass
  6. MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA.

    • Alberto Serrano-Pozo &
    • Bradley T Hyman
  7. Institute of Neuropathology, University of Freiburg, Freiburg, Germany.

    • Alexandra Müller &
    • Marco Prinz
  8. Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg, Germany.

    • Marco Prinz
  9. Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.

    • Christian Haass


T.B., C.H. and M.M.-L. conceived the experiments. T.B., N.K., J.F.M., D.L., S.T., C.A.-A., B.N., F.K. and A.S.-P. performed experiments. B.T.H. provided human brain samples. A.M., D.L. and M.P. performed electron microscopy. H.S., S.T., F.K. and A.S.-P. provided important experimental guidance. T.B., J.F.M., H.S., B.T.H., C.H. and M.M.-L. discussed the results. T.B., J.F.M. and M.M.-L. wrote the manuscript. M.M.-L. supervised the project and coordinated the study. All authors edited the paper.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Supplementary information

PDF files

  1. Supplementary Text and Figures (1,674 KB)

    Supplementary figures 1–8, Supplementary tables 1–2 & Supplementary Methods

Additional data