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Zinc binding directly regulates tau toxicity independent of tau hyperphosphorylation.

Huang Y, Wu Z, Cao Y, Lang M, Lu B, Zhou B - Cell Rep (2014)

Bottom Line: Tau hyperphosphorylation is thought to underlie tauopathy.Elimination of zinc binding through amino acid substitution of Cys residues has a minimal effect on phosphorylation levels yet essentially eliminates Tau toxicity.These results indicate zinc binding is a substantial contributor to tauopathy and have implications for therapy development.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.

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Related in: MedlinePlus

Substitution of Zinc Binding Residues Essentially Eliminates the Zinc Responsiveness of Tau Toxicity(A) Lifespans of Tau*C2A flies are essentially inert to zinc changes. Shown here are Tau*, Tau*S2A, and Tau*C2A flies under zinc treatment. Elav-Gal4 was used to express proteins in the CNS. Tau*-NF versus Tau*-Zn, p < 0.0001; Tau*S2A-NF versus Tau*S2A-Zn, p < 0.0001; Tau*C2A-NF versus Tau*C2A-Zn, p ≈ 0.05. NF, normal food.(B1 and B2) Brain degeneration is not significantly affected by zinc treatment in Tau*C2A flies. Shown here are H&E-stained paraffin brain sections of Tau*, Tau*C2A, and Tau*S2A flies under zinc treatment. The scale bar represents 50 μm. Green arrowheads indicate some of the many degenerated vacuoles. A quantitative and statistical analysis of B1 is shown in B2. Data represent mean ± SEM and were compared with NF group within each genotype. *p < 0.05; **p < 0.01. n.s., p > 0.05, not significant.(C) Tau*C2A does not respond to zinc incubation in vitro. TEM images of Tau*, Tau*S2A, and Tau*C2A proteins coincubated with zinc are presented. The scale bar represents 200 nm. The concentrations of Tau*, Tau*S2A, and Tau*C2A were adjusted to ~50 μg/ml before the metal incubation.(D) Zinc treatment increases the insoluble species of Tau protein in vivo. Insoluble Tau fractions were extracted from fly heads using the extraction buffer containing 1% SDS and detected by Tau5 antibody. Actin was used as a control to show comparable loadings among samples.
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Figure 5: Substitution of Zinc Binding Residues Essentially Eliminates the Zinc Responsiveness of Tau Toxicity(A) Lifespans of Tau*C2A flies are essentially inert to zinc changes. Shown here are Tau*, Tau*S2A, and Tau*C2A flies under zinc treatment. Elav-Gal4 was used to express proteins in the CNS. Tau*-NF versus Tau*-Zn, p < 0.0001; Tau*S2A-NF versus Tau*S2A-Zn, p < 0.0001; Tau*C2A-NF versus Tau*C2A-Zn, p ≈ 0.05. NF, normal food.(B1 and B2) Brain degeneration is not significantly affected by zinc treatment in Tau*C2A flies. Shown here are H&E-stained paraffin brain sections of Tau*, Tau*C2A, and Tau*S2A flies under zinc treatment. The scale bar represents 50 μm. Green arrowheads indicate some of the many degenerated vacuoles. A quantitative and statistical analysis of B1 is shown in B2. Data represent mean ± SEM and were compared with NF group within each genotype. *p < 0.05; **p < 0.01. n.s., p > 0.05, not significant.(C) Tau*C2A does not respond to zinc incubation in vitro. TEM images of Tau*, Tau*S2A, and Tau*C2A proteins coincubated with zinc are presented. The scale bar represents 200 nm. The concentrations of Tau*, Tau*S2A, and Tau*C2A were adjusted to ~50 μg/ml before the metal incubation.(D) Zinc treatment increases the insoluble species of Tau protein in vivo. Insoluble Tau fractions were extracted from fly heads using the extraction buffer containing 1% SDS and detected by Tau5 antibody. Actin was used as a control to show comparable loadings among samples.

Mentions: If loss of toxicity for Tau*C2A is the result of loss of zinc binding, and for Tau*S2A from phosphorylation reduction, we expect the zinc responses of Tau*C2A, Tau*S2A, and Tau* flies to be different. Indeed, unlike that of Tau* and Tau*S2A flies, zinc could not appreciably affect the lifespan of Tau*C2A flies (Figure 5A). However, for similarly nontoxic Tau*S2A, which is able to bind zinc, zinc-responsiveness was still apparent (Figure 5A). Paraffin brain sections also revealed that zinc could not influence the toxicity of Tau*C2A: when treated with zinc, the neurodegeneration in Tau*C2A flies did not noticeably worsen as measured by the number of vacuoles formed in the brains (Figures 5B1 and 5B2).


Zinc binding directly regulates tau toxicity independent of tau hyperphosphorylation.

Huang Y, Wu Z, Cao Y, Lang M, Lu B, Zhou B - Cell Rep (2014)

Substitution of Zinc Binding Residues Essentially Eliminates the Zinc Responsiveness of Tau Toxicity(A) Lifespans of Tau*C2A flies are essentially inert to zinc changes. Shown here are Tau*, Tau*S2A, and Tau*C2A flies under zinc treatment. Elav-Gal4 was used to express proteins in the CNS. Tau*-NF versus Tau*-Zn, p < 0.0001; Tau*S2A-NF versus Tau*S2A-Zn, p < 0.0001; Tau*C2A-NF versus Tau*C2A-Zn, p ≈ 0.05. NF, normal food.(B1 and B2) Brain degeneration is not significantly affected by zinc treatment in Tau*C2A flies. Shown here are H&E-stained paraffin brain sections of Tau*, Tau*C2A, and Tau*S2A flies under zinc treatment. The scale bar represents 50 μm. Green arrowheads indicate some of the many degenerated vacuoles. A quantitative and statistical analysis of B1 is shown in B2. Data represent mean ± SEM and were compared with NF group within each genotype. *p < 0.05; **p < 0.01. n.s., p > 0.05, not significant.(C) Tau*C2A does not respond to zinc incubation in vitro. TEM images of Tau*, Tau*S2A, and Tau*C2A proteins coincubated with zinc are presented. The scale bar represents 200 nm. The concentrations of Tau*, Tau*S2A, and Tau*C2A were adjusted to ~50 μg/ml before the metal incubation.(D) Zinc treatment increases the insoluble species of Tau protein in vivo. Insoluble Tau fractions were extracted from fly heads using the extraction buffer containing 1% SDS and detected by Tau5 antibody. Actin was used as a control to show comparable loadings among samples.
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Figure 5: Substitution of Zinc Binding Residues Essentially Eliminates the Zinc Responsiveness of Tau Toxicity(A) Lifespans of Tau*C2A flies are essentially inert to zinc changes. Shown here are Tau*, Tau*S2A, and Tau*C2A flies under zinc treatment. Elav-Gal4 was used to express proteins in the CNS. Tau*-NF versus Tau*-Zn, p < 0.0001; Tau*S2A-NF versus Tau*S2A-Zn, p < 0.0001; Tau*C2A-NF versus Tau*C2A-Zn, p ≈ 0.05. NF, normal food.(B1 and B2) Brain degeneration is not significantly affected by zinc treatment in Tau*C2A flies. Shown here are H&E-stained paraffin brain sections of Tau*, Tau*C2A, and Tau*S2A flies under zinc treatment. The scale bar represents 50 μm. Green arrowheads indicate some of the many degenerated vacuoles. A quantitative and statistical analysis of B1 is shown in B2. Data represent mean ± SEM and were compared with NF group within each genotype. *p < 0.05; **p < 0.01. n.s., p > 0.05, not significant.(C) Tau*C2A does not respond to zinc incubation in vitro. TEM images of Tau*, Tau*S2A, and Tau*C2A proteins coincubated with zinc are presented. The scale bar represents 200 nm. The concentrations of Tau*, Tau*S2A, and Tau*C2A were adjusted to ~50 μg/ml before the metal incubation.(D) Zinc treatment increases the insoluble species of Tau protein in vivo. Insoluble Tau fractions were extracted from fly heads using the extraction buffer containing 1% SDS and detected by Tau5 antibody. Actin was used as a control to show comparable loadings among samples.
Mentions: If loss of toxicity for Tau*C2A is the result of loss of zinc binding, and for Tau*S2A from phosphorylation reduction, we expect the zinc responses of Tau*C2A, Tau*S2A, and Tau* flies to be different. Indeed, unlike that of Tau* and Tau*S2A flies, zinc could not appreciably affect the lifespan of Tau*C2A flies (Figure 5A). However, for similarly nontoxic Tau*S2A, which is able to bind zinc, zinc-responsiveness was still apparent (Figure 5A). Paraffin brain sections also revealed that zinc could not influence the toxicity of Tau*C2A: when treated with zinc, the neurodegeneration in Tau*C2A flies did not noticeably worsen as measured by the number of vacuoles formed in the brains (Figures 5B1 and 5B2).

Bottom Line: Tau hyperphosphorylation is thought to underlie tauopathy.Elimination of zinc binding through amino acid substitution of Cys residues has a minimal effect on phosphorylation levels yet essentially eliminates Tau toxicity.These results indicate zinc binding is a substantial contributor to tauopathy and have implications for therapy development.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.

Show MeSH
Related in: MedlinePlus