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Two C-terminal sequence variations determine differential neurotoxicity between human and mouse α-synuclein

Landeck, Natalie LU ; Strathearn, Katherine E. ; Ysselstein, Daniel ; Buck, Kerstin LU ; Dutta, Sayan ; Banerjee, Siddhartha ; Lv, Zhengjian ; Hulleman, John D. ; Hindupur, Jagadish and Lin, Li Kai , et al. (2020) In Molecular Neurodegeneration 15(1).
Abstract

Background: α-Synuclein (aSyn) aggregation is thought to play a central role in neurodegenerative disorders termed synucleinopathies, including Parkinson's disease (PD). Mouse aSyn contains a threonine residue at position 53 that mimics the human familial PD substitution A53T, yet in contrast to A53T patients, mice show no evidence of aSyn neuropathology even after aging. Here, we studied the neurotoxicity of human A53T, mouse aSyn, and various human-mouse chimeras in cellular and in vivo models, as well as their biochemical properties relevant to aSyn pathobiology. Methods: Primary midbrain cultures transduced with aSyn-encoding adenoviruses were analyzed immunocytochemically to determine relative dopaminergic neuron viability. Brain... (More)

Background: α-Synuclein (aSyn) aggregation is thought to play a central role in neurodegenerative disorders termed synucleinopathies, including Parkinson's disease (PD). Mouse aSyn contains a threonine residue at position 53 that mimics the human familial PD substitution A53T, yet in contrast to A53T patients, mice show no evidence of aSyn neuropathology even after aging. Here, we studied the neurotoxicity of human A53T, mouse aSyn, and various human-mouse chimeras in cellular and in vivo models, as well as their biochemical properties relevant to aSyn pathobiology. Methods: Primary midbrain cultures transduced with aSyn-encoding adenoviruses were analyzed immunocytochemically to determine relative dopaminergic neuron viability. Brain sections prepared from rats injected intranigrally with aSyn-encoding adeno-associated viruses were analyzed immunohistochemically to determine nigral dopaminergic neuron viability and striatal dopaminergic terminal density. Recombinant aSyn variants were characterized in terms of fibrillization rates by measuring thioflavin T fluorescence, fibril morphologies via electron microscopy and atomic force microscopy, and protein-lipid interactions by monitoring membrane-induced aSyn aggregation and aSyn-mediated vesicle disruption. Statistical tests consisted of ANOVA followed by Tukey's multiple comparisons post hoc test and the Kruskal-Wallis test followed by a Dunn's multiple comparisons test or a two-tailed Mann-Whitney test. Results: Mouse aSyn was less neurotoxic than human aSyn A53T in cell culture and in rat midbrain, and data obtained for the chimeric variants indicated that the human-to-mouse substitutions D121G and N122S were at least partially responsible for this decrease in neurotoxicity. Human aSyn A53T and a chimeric variant with the human residues D and N at positions 121 and 122 (respectively) showed a greater propensity to undergo membrane-induced aggregation and to elicit vesicle disruption. Differences in neurotoxicity among the human, mouse, and chimeric aSyn variants correlated weakly with differences in fibrillization rate or fibril morphology. Conclusions: Mouse aSyn is less neurotoxic than the human A53T variant as a result of inhibitory effects of two C-terminal amino acid substitutions on membrane-induced aSyn aggregation and aSyn-mediated vesicle permeabilization. Our findings highlight the importance of membrane-induced self-assembly in aSyn neurotoxicity and suggest that inhibiting this process by targeting the C-terminal domain could slow neurodegeneration in PD and other synucleinopathy disorders.

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Contribution to journal
publication status
published
subject
keywords
Adeno-associated virus, Aggregation, Alpha-synuclein, Amyloid, Fibril, Membrane, Neurodegeneration, Parkinson's disease, Phospholipid, Synucleinopathy
in
Molecular Neurodegeneration
volume
15
issue
1
article number
49
publisher
BioMed Central (BMC)
external identifiers
  • scopus:85090748667
  • pmid:32900375
ISSN
1750-1326
DOI
10.1186/s13024-020-00380-w
language
English
LU publication?
yes
id
da575ad2-1245-4a0e-8aac-5541c4dbd4d8
date added to LUP
2020-09-29 13:44:47
date last changed
2020-09-30 06:44:39
@article{da575ad2-1245-4a0e-8aac-5541c4dbd4d8,
  abstract     = {<p>Background: α-Synuclein (aSyn) aggregation is thought to play a central role in neurodegenerative disorders termed synucleinopathies, including Parkinson's disease (PD). Mouse aSyn contains a threonine residue at position 53 that mimics the human familial PD substitution A53T, yet in contrast to A53T patients, mice show no evidence of aSyn neuropathology even after aging. Here, we studied the neurotoxicity of human A53T, mouse aSyn, and various human-mouse chimeras in cellular and in vivo models, as well as their biochemical properties relevant to aSyn pathobiology. Methods: Primary midbrain cultures transduced with aSyn-encoding adenoviruses were analyzed immunocytochemically to determine relative dopaminergic neuron viability. Brain sections prepared from rats injected intranigrally with aSyn-encoding adeno-associated viruses were analyzed immunohistochemically to determine nigral dopaminergic neuron viability and striatal dopaminergic terminal density. Recombinant aSyn variants were characterized in terms of fibrillization rates by measuring thioflavin T fluorescence, fibril morphologies via electron microscopy and atomic force microscopy, and protein-lipid interactions by monitoring membrane-induced aSyn aggregation and aSyn-mediated vesicle disruption. Statistical tests consisted of ANOVA followed by Tukey's multiple comparisons post hoc test and the Kruskal-Wallis test followed by a Dunn's multiple comparisons test or a two-tailed Mann-Whitney test. Results: Mouse aSyn was less neurotoxic than human aSyn A53T in cell culture and in rat midbrain, and data obtained for the chimeric variants indicated that the human-to-mouse substitutions D121G and N122S were at least partially responsible for this decrease in neurotoxicity. Human aSyn A53T and a chimeric variant with the human residues D and N at positions 121 and 122 (respectively) showed a greater propensity to undergo membrane-induced aggregation and to elicit vesicle disruption. Differences in neurotoxicity among the human, mouse, and chimeric aSyn variants correlated weakly with differences in fibrillization rate or fibril morphology. Conclusions: Mouse aSyn is less neurotoxic than the human A53T variant as a result of inhibitory effects of two C-terminal amino acid substitutions on membrane-induced aSyn aggregation and aSyn-mediated vesicle permeabilization. Our findings highlight the importance of membrane-induced self-assembly in aSyn neurotoxicity and suggest that inhibiting this process by targeting the C-terminal domain could slow neurodegeneration in PD and other synucleinopathy disorders.</p>},
  author       = {Landeck, Natalie and Strathearn, Katherine E. and Ysselstein, Daniel and Buck, Kerstin and Dutta, Sayan and Banerjee, Siddhartha and Lv, Zhengjian and Hulleman, John D. and Hindupur, Jagadish and Lin, Li Kai and Padalkar, Sonal and Stanciu, Lia A. and Lyubchenko, Yuri L. and Kirik, Deniz and Rochet, Jean Christophe},
  issn         = {1750-1326},
  language     = {eng},
  number       = {1},
  publisher    = {BioMed Central (BMC)},
  series       = {Molecular Neurodegeneration},
  title        = {Two C-terminal sequence variations determine differential neurotoxicity between human and mouse α-synuclein},
  url          = {http://dx.doi.org/10.1186/s13024-020-00380-w},
  doi          = {10.1186/s13024-020-00380-w},
  volume       = {15},
  year         = {2020},
}