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Synergistic influence of phosphorylation and metal ions on tau oligomer formation and coaggregation with α-synuclein at the single molecule level.

Nübling G, Bader B, Levin J, Hildebrandt J, Kretzschmar H, Giese A - Mol Neurodegener (2012)

Bottom Line: While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood.We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers.Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Neuropathology and Prion Research, Ludwig-Maximilians-Universität, Feodor-Lynen-Str, 23, 81377, Munich, Germany.

ABSTRACT

Background: Fibrillar amyloid-like deposits and co-deposits of tau and α-synuclein are found in several common neurodegenerative diseases. Recent evidence indicates that small oligomers are the most relevant toxic aggregate species. While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood.

Results: We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers. We show that Al3+ at physiologically relevant concentrations and tau phosphorylation by GSK-3β exert synergistic effects on the formation of a distinct SDS-resistant tau oligomer species even at nanomolar protein concentration. Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers.

Conclusions: Our findings provide a new perspective on interactions of tau phosphorylation, metal ions, and the formation of potentially toxic oligomer species, and elucidate molecular crosstalks between different aggregation pathways involved in neurodegeneration.

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Monomeric α-syn preferably coaggregates with pTau oligomers in presence of metal ions.A. Cross-correlation amplitudes (G (0)) show mild coaggregation of α-syn monomers with pre-formed tau oligomers induced by DMSO and Fe3+, while Al3+ promotes intense coaggregation. Combinations of DMSO and metal ions show a synergistic effect especially for mTau. 2D histograms show the formation of smaller mixed oligomers induced by DMSO compared to the metal ions. B. Cross-correlation amplitude before (T0) and 100 min after (T100) addition of SDS to the aggregation assay. Significant reductions of aggregation levels at T100 are indicated by the symbols over the error bars, while significant differences between pTau and mTau are indicated by the symbols over the wide bars. C. Cross correlation amplitude at T100 normalized against T0 shows increased SDS-resistance of metal ion induced oligomers compared to DMSO. Measurements were taken from 20 independent samples; each sample was measured four times. Levels of significance are displayed as * = p < 0.05; ** = p < 0.01; ‡ = p < 0.001.
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Figure 4: Monomeric α-syn preferably coaggregates with pTau oligomers in presence of metal ions.A. Cross-correlation amplitudes (G (0)) show mild coaggregation of α-syn monomers with pre-formed tau oligomers induced by DMSO and Fe3+, while Al3+ promotes intense coaggregation. Combinations of DMSO and metal ions show a synergistic effect especially for mTau. 2D histograms show the formation of smaller mixed oligomers induced by DMSO compared to the metal ions. B. Cross-correlation amplitude before (T0) and 100 min after (T100) addition of SDS to the aggregation assay. Significant reductions of aggregation levels at T100 are indicated by the symbols over the error bars, while significant differences between pTau and mTau are indicated by the symbols over the wide bars. C. Cross correlation amplitude at T100 normalized against T0 shows increased SDS-resistance of metal ion induced oligomers compared to DMSO. Measurements were taken from 20 independent samples; each sample was measured four times. Levels of significance are displayed as * = p < 0.05; ** = p < 0.01; ‡ = p < 0.001.

Mentions: Giasson et al. showed that tau and α-syn induce each other’s filament formation, and that some of the fibrils formed in presence of both proteins comprise tau and α-syn segments [41]. Such findings suggest that these segments are either assembled by end to end annealing of short filament fragments, or that such fragments act as seeds for both proteins. To evaluate the effect of tau phosphorylation on the interaction of tau oligomers with monomeric α-syn, tau488 was first incubated in presence of 1% DMSO, 10 μM Fe3+, 10 μM Al3+, and combinations of these agents for 90 minutes to generate pre-formed tau oligomers. α-Syn647 monomers were then added to the assay and measurements were conducted (Figure 4A).


Synergistic influence of phosphorylation and metal ions on tau oligomer formation and coaggregation with α-synuclein at the single molecule level.

Nübling G, Bader B, Levin J, Hildebrandt J, Kretzschmar H, Giese A - Mol Neurodegener (2012)

Monomeric α-syn preferably coaggregates with pTau oligomers in presence of metal ions.A. Cross-correlation amplitudes (G (0)) show mild coaggregation of α-syn monomers with pre-formed tau oligomers induced by DMSO and Fe3+, while Al3+ promotes intense coaggregation. Combinations of DMSO and metal ions show a synergistic effect especially for mTau. 2D histograms show the formation of smaller mixed oligomers induced by DMSO compared to the metal ions. B. Cross-correlation amplitude before (T0) and 100 min after (T100) addition of SDS to the aggregation assay. Significant reductions of aggregation levels at T100 are indicated by the symbols over the error bars, while significant differences between pTau and mTau are indicated by the symbols over the wide bars. C. Cross correlation amplitude at T100 normalized against T0 shows increased SDS-resistance of metal ion induced oligomers compared to DMSO. Measurements were taken from 20 independent samples; each sample was measured four times. Levels of significance are displayed as * = p < 0.05; ** = p < 0.01; ‡ = p < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472288&req=5

Figure 4: Monomeric α-syn preferably coaggregates with pTau oligomers in presence of metal ions.A. Cross-correlation amplitudes (G (0)) show mild coaggregation of α-syn monomers with pre-formed tau oligomers induced by DMSO and Fe3+, while Al3+ promotes intense coaggregation. Combinations of DMSO and metal ions show a synergistic effect especially for mTau. 2D histograms show the formation of smaller mixed oligomers induced by DMSO compared to the metal ions. B. Cross-correlation amplitude before (T0) and 100 min after (T100) addition of SDS to the aggregation assay. Significant reductions of aggregation levels at T100 are indicated by the symbols over the error bars, while significant differences between pTau and mTau are indicated by the symbols over the wide bars. C. Cross correlation amplitude at T100 normalized against T0 shows increased SDS-resistance of metal ion induced oligomers compared to DMSO. Measurements were taken from 20 independent samples; each sample was measured four times. Levels of significance are displayed as * = p < 0.05; ** = p < 0.01; ‡ = p < 0.001.
Mentions: Giasson et al. showed that tau and α-syn induce each other’s filament formation, and that some of the fibrils formed in presence of both proteins comprise tau and α-syn segments [41]. Such findings suggest that these segments are either assembled by end to end annealing of short filament fragments, or that such fragments act as seeds for both proteins. To evaluate the effect of tau phosphorylation on the interaction of tau oligomers with monomeric α-syn, tau488 was first incubated in presence of 1% DMSO, 10 μM Fe3+, 10 μM Al3+, and combinations of these agents for 90 minutes to generate pre-formed tau oligomers. α-Syn647 monomers were then added to the assay and measurements were conducted (Figure 4A).

Bottom Line: While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood.We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers.Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Neuropathology and Prion Research, Ludwig-Maximilians-Universität, Feodor-Lynen-Str, 23, 81377, Munich, Germany.

ABSTRACT

Background: Fibrillar amyloid-like deposits and co-deposits of tau and α-synuclein are found in several common neurodegenerative diseases. Recent evidence indicates that small oligomers are the most relevant toxic aggregate species. While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood.

Results: We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers. We show that Al3+ at physiologically relevant concentrations and tau phosphorylation by GSK-3β exert synergistic effects on the formation of a distinct SDS-resistant tau oligomer species even at nanomolar protein concentration. Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers.

Conclusions: Our findings provide a new perspective on interactions of tau phosphorylation, metal ions, and the formation of potentially toxic oligomer species, and elucidate molecular crosstalks between different aggregation pathways involved in neurodegeneration.

Show MeSH
Related in: MedlinePlus