Impairment of microtubule system increases α-synuclein aggregation and toxicity

doi:10.1016/j.bbrc.2007.11.020

Biochemical and Biophysical Research Communications

Volume 365, Issue 4, 25 January 2008, Pages 628-635

https://doi.org/10.1016/j.bbrc.2007.11.020 Get rights and content

Abstract

The accumulation of fibrillar form of α-synuclein (α-syn) has been implicated in Parkinson’s disease. Here we show that tubulin can stimulate α-syn fibrillization in vitro in different ways depending on its oligomeric status. The physiological significance of tubulin-seeded α-syn fibrillization is demonstrated by using Saccharomyces cerevisiae as a model system. Perturbation of microtubule system either by treating benomyl that inhibits microtubule assembly or by deleting genes involved in microtubule biogenesis, stimulates α-syn aggregation and toxicity. These results suggest that impairment of the microtubule system may act as a risk factor deteriorating the α-syn-mediated neurodegeneration by increasing the chance of tubulin-seeded α-syn aggregation.

Section snippets

Materials and methods

Yeast strains and culture conditions. The yeast strains used in this study are W303-1A (MATa ade2-1 can1-100 his3-11, 15 leu2-3, 112 trp1-1 ura3) and BY4741 (MATa hisΔ1 leuΔ0 met15Δ0 ura3Δ0). BY4741-derived deletion strains were kindly provided by Dr. Won-Ki Huh. W303-1A with a genome-integrated α-Syn-GFP gene under the control of GAL1 promoter was generated by transformation of the cells with pRS305GAL1- α-Syn-GFP (see supplementary material for plasmid construction) after linearization of the

Tubulin accelerates α-syn fibrillization in vitro in different ways depending on its oligomeric status

Tubulin has been shown to stimulate α-syn fibrillization in vitro, and co-localize with α-syn in pathological structures of synucleinopathies including Lewy bodies and Lewy neuritis, suggesting its role as prodegenerative factors [9]. However, the physiological significance of tubulin in seeding α-syn fibrillization still remains to be resolved. In order to further investigate the role of tubulin in α-syn aggregation and toxicity, we reexamined the effect of tubulin on α-syn fibrillization in

Discussion

In the present study, we used a yeast model system to show that perturbation of microtubule system either by treating benomyl that inhibits microtubule assembly or by deleting genes involved in tubulin folding and microtubule biogenesis, not only stimulates α-syn aggregation, but also enhances cytotoxicity. These results provide the first physiological evidence that tubulin-seeded fibrillization of α-syn might occur in vivo and function as one of the underlying mechanisms increasing

Acknowledgments

We thank Dr. Won-Ki Huh for yeast strains. This work was supported by grants from the Seoul R&D Program (10538) through Institute of Bioengineering, Seoul National University, and Korea Research Foundation (2005-005-J16002).

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Cited by (28)

Cross-talk between α-synuclein and the microtubule cytoskeleton in neurodegeneration
2023, Experimental Neurology
Citation Excerpt :
Thus, the strategy of preventing their formation or sequestering these species has the potential to be the correct approach. Interestingly, among the players that could influence the aggregation processes there is the microtubule system (Alim et al., 2002; Esteves, 2010; Kim et al., 2008; Nakayama et al., 2012; Outeiro et al., 2007). This might suggest that targeting the interplay between α-synuclein and microtubules could prevent α-synuclein aggregation.
Looking at the puzzle that depicts the molecular determinants in neurodegeneration, many pieces are lacking and multiple interconnections among key proteins and intracellular pathways still remain unclear. Here we focus on the concerted action of α-synuclein and the microtubule cytoskeleton, whose interplay, indeed, is emerging but remains largely unexplored in both its physiology and pathology. α-Synuclein is a key protein involved in neurodegeneration, underlying those diseases termed synucleinopathies. Its propensity to interact with other proteins and structures renders the identification of neuronal death trigger extremely difficult. Conversely, the unbalance of microtubule cytoskeleton in terms of structure, dynamics and function is emerging as a point of convergence in neurodegeneration. Interestingly, α-synuclein and microtubules have been shown to interact and mediate cross-talks with other intracellular structures. This is supported by an increasing amount of evidence ranging from their direct interaction to the engagement of in-common partners and culminating with their respective impact on microtubule-dependent neuronal functions. Last, but not least, it is becoming even more clear that α-synuclein and tubulin work synergically towards pathological aggregation, ultimately resulting in neurodegeneration. In this respect, we supply a novel perspective towards the understanding of α-synuclein biology and, most importantly, of the link between α-synuclein with microtubule cytoskeleton and its impact for neurodegeneration and future development of novel therapeutic strategies.
Mechanisms of alpha-synuclein toxicity: An update and outlook
2020, Progress in Brain Research
Citation Excerpt :
Interestingly, the prion protein was also identified as a possible sensor for aSyn (Aulic et al., 2017; Bras et al., 2018; Ferreira et al., 2017). aSyn can also be actively internalized via endocytosis, and be delivered to different organelles (Desplats et al., 2009; Hansen et al., 2011; Kim et al., 2008; Lee et al., 2008a,b; Volpicelli-Daley et al., 2011). Different cell types in the brain, such as oligodendrocytes, astrocytes, and microglia, can uptake aSyn assemblies (Braidy et al., 2013; Hoffmann et al., 2016; Kim et al., 2013; Lindstrom et al., 2017; Reyes et al., 2014).
Alpha-synuclein (aSyn) was identified as the main component of inclusions that define synucleinopathies more than 20 years ago. Since then, aSyn has been extensively studied in an attempt to unravel its roles in both physiology and pathology. Today, studying the mechanisms of aSyn toxicity remains in the limelight, leading to the identification of novel pathways involved in pathogenesis.
In this chapter, we address the molecular mechanisms involved in synucleinopathies, from aSyn misfolding and aggregation to the various cellular effects and pathologies associated. In particular, we review our current understanding of the mechanisms involved in the spreading of aSyn between different cells, from the periphery to the brain, and back. Finally, we also review recent studies on the contribution of inflammation and the gut microbiota to pathology in synucleinopathies. Despite significant advances in our understanding of the molecular mechanisms involved, we still lack an integrated understanding of the pathways leading to neurodegeneration in PD and other synucleinopathies, compromising our ability to develop novel therapeutic strategies.
Acetylation as a major determinant to microtubule-dependent autophagy: Relevance to Alzheimer's and Parkinson disease pathology
2019, Biochimica et Biophysica Acta - Molecular Basis of Disease
Citation Excerpt :
Additionally, Alim and colleagues found that ASYN is also a tubulin associated/binding protein and that WT ASYN induces tubulin polymerization into MTs whereas ASYN mutants lose this potential [9]. On the other hand tubulin induces ASYN fibrillization in yeast, rat and human brain [10]. The loss of MT assembly affects intraneuronal axonal transport, namely mitochondrial anterograde transport and autophagic vesicles (AVs) retrograde transport.
Protein post-translational modifications (PTMs) that potentiate protein aggregation have been implicated in several neurological disorders, including Alzheimer's (AD) and Parkinson's disease (PD). In fact, Tau and alpha-synuclein (ASYN) undergo several PTMs potentiating their aggregation and neurotoxicity.
Recent data posits a role for acetylation in Tau and ASYN aggregation. Herein we aimed to clarify the role of Sirtuin-2 (SIRT2) and HDAC6 tubulin deacetylases as well as p300 acetyltransferase in AD and PD neurodegeneration. We used transmitochondrial cybrids that recapitulate pathogenic alterations observed in sporadic PD and AD patient brains and ASYN and Tau cellular models.
We confirmed that Tau protein and ASYN are microtubules (MTs)-associated proteins (MAPs). Moreover, our results suggest that α-tubulin acetylation induced by SIRT2 inhibition is functionally associated with the improvement of MT dynamic determined by decreased Tau phosphorylation and by increased Tau/tubulin and ASYN/tubulin binding. Our data provide a strong evidence for a functional role of tubulin and MAPs acetylation on autophagic vesicular traffic and cargo clearance. Additionally, we showed that an accumulation of ASYN oligomers imbalance mitochondrial dynamics, which further compromise autophagy. We also demonstrated that an increase in Tau acetylation is associated with Tau phosphorylation. We found that p300, HDAC6 and SIRT2 influences Tau phosphorylation and autophagic flux in AD. In addition, we demonstrated that p300 and HDAC6 modulate Tau and Tubulin acetylation.
Overall, our data disclose the role of Tau and ASYN modifications through acetylation in AD and PD pathology, respectively. Moreover, this study indicates that MTs can be a promising therapeutic target in the field of neurodegenerative disorders in which intracellular transport is altered.
The function of α-synuclein
2013, Neuron
Human genetics has indicated a causal role for the protein α-synuclein in the pathogenesis of familial Parkinson’s disease (PD), and the aggregation of synuclein in essentially all patients with PD suggests a central role for this protein in the sporadic disorder. Indeed, the accumulation of misfolded α-synuclein now defines multiple forms of neural degeneration. Like many of the proteins that accumulate in other neurodegenerative disorders, however, the normal function of synuclein remains poorly understood. In this article, we review the role of synuclein at the nerve terminal and in membrane remodeling. We also consider the prion-like propagation of misfolded synuclein as a mechanism for the spread of degeneration through the neuraxis.
α-synuclein oligomers impair neuronal microtubule-kinesin interplay
2013, Journal of Biological Chemistry
Citation Excerpt :
Furthermore, overexpression of α-Syn oligomeric mutants resulted in neurite swellings in rat substantia nigra neurons (13). The interaction of α-Syn with tubulin and MTs was shown in vitro and in vivo, and α-Syn overexpression and aggregation was associated with disrupted MT networks (16–22). Together, these data strongly suggest alterations in the intracellular transport machinery in synucleinopathies.
Early α-synuclein (α-Syn)-induced alterations are neurite pathologies resulting in Lewy neurites. α-Syn oligomers are a toxic species in synucleinopathies and are suspected to cause neuritic pathology. To investigate how α-Syn oligomers may be linked to aberrant neurite pathology, we modeled different stages of α-Syn aggregation in vitro and investigated the interplay of α-Syn aggregates with proteins involved in axonal transport. The interaction of wild type α-Syn (WTS) and α-Syn variants (E57K, A30P, and aSyn(30–110)) with kinesin, tubulin, and the microtubule (MT)-associated proteins, MAP2 and Tau, is stronger for multimers than for monomers. WTS seeds but not α-Syn oligomers significantly and dose-dependently reduced Tau-promoted MT assembly in vitro. In contrast, MT gliding velocity across kinesin-coated surfaces was significantly decreased in the presence of α-Syn oligomers but not WTS seeds or fibrils (aSyn(30–110) multimers). In a human dopaminergic neuronal cell line, mild overexpression of the oligomerizing E57K α-Syn variant significantly impaired neurite network morphology without causing profound cell death. In accordance with these findings, MT stability, neuritic kinesin, and neuritic kinesin-dependent cargoes were significantly reduced by the presence of α-Syn oligomers. In summary, different α-Syn species act divergently on the axonal transport machinery. These findings provide new insights into α-Syn oligomer-driven neuritic pathology as one of the earliest events in synucleinopathies.
Background: α-Synuclein aggregates cause early neurite pathology by as yet unknown mechanisms.
Results: α-Synuclein oligomers and seeds decrease microtubule stability, kinesin-microtubule interaction, cellular cargo distribution, and neurite network morphology.
Conclusion: Various α-synuclein species interact differently with proteins of axonal transport.
Significance: The impairment of the microtubule-kinesin function by α-synuclein oligomers drives early neurite pathology.
Pathological roles of α-synuclein in neurological disorders
2011, The Lancet Neurology
Substantial genetic, neuropathological, and biochemical evidence implicates the presynaptic neuronal protein α-synuclein in Parkinson's disease and related Lewy body disorders. How dysregulation of α-synuclein leads to neurodegeneration is, however, unclear. Soluble oligomeric, but not fully fibrillar, α-synuclein is thought to be toxic. The major neuronal target of aberrant α-synuclein might be the synapse. The effects of aberrant α-synuclein might include alteration of calcium homoeostasis or mitochondrial fragmentation and, in turn, mitochondrial dysfunction, which could link α-synuclein dysfunction to recessive and toxin-induced parkinsonism. α-Synuclein also seems to be linked to other genetic forms of Parkinson's disease, such as those linked to mutations in GBA or LRRK2, possibly through common effects on autophagy and lysosomal function. Finally, α-synuclein is physiologically secreted, and this extracellular form could lead to the spread of pathological accumulations and disease progression. Consequently, factors that regulate the levels, post-translational modifications, specific aberrant cellular effects, or secretion of α-synuclein might be targets for therapy.

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¹: These authors contributed equally to this work.

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Impairment of microtubule system increases α-synuclein aggregation and toxicity

Abstract

Section snippets

Materials and methods

Tubulin accelerates α-syn fibrillization in vitro in different ways depending on its oligomeric status

Discussion

Acknowledgments

J. Biol. Chem.

J. Biol. Chem.

J. Mol. Biol.

J. Biol. Chem.

J. Struct. Biol.

Unfolding the role of protein misfolding in neurodegenerative diseases

Nat. Rev. Neurosci.

Opinion: what is the role of protein aggregation in neurodegeneration?

Nat. Rev. Mol. Cell Biol.

The aggregation and fibrillation of alpha-synuclein

Acc. Chem. Res.

Lewy bodies

Proc. Natl. Acad. Sci. USA

The role of alpha-synuclein in Parkinson’s disease: insights from animal models

Nat. Rev. Neurosci.

Copper(II)-induced self-oligomerization of alpha-synuclein

Biochem. J.

Oxidative damage linked to neurodegeneration by selective alpha-synuclein nitration in synucleinopathy lesions

Science

Initiation and synergistic fibrillization of tau and alpha-synuclein

Science