Wang, Xuan et al. (2019) International Worm Meeting "Insights into the effects of alpha-synuclein in age-dependent neuronal maintenance, physiological function and pathological mechanism."

Wang, Xuan, Doi, Motomichi

[International Worm Meeting, 2019]

Parkinson's disease (PD) is the most frequent neurodegenerative disorder as well as Alzheimer's disease. It is characterized by the loss of dopaminergic neurons in substantia nigra pars compacta and the formation of Lewy body inclusion which is composed of aggregated ?-synuclein (?-syn). Several studies indicate that ?-syn can assemble into oligomers and fibrils via hydrophobic structure in vitro, and oligomers seem to be much more toxic. Overexpressing wild-type ?-syn or PD-linked mutant forms causes neurodegeneration and motor deficits in many model systems. In Caenorhabditis elegans, for example, ?-syn in body wall muscles or dopaminergic neurons causes deficits in movement and cell death respectively. Although the neurotoxicity of pathological ?-syn have been elucidated, native physiological functions of this protein are not well known yet. In addition, some studies indicate that ?-syn can be transmitted from cell to cell via endo-/exosomal pathways. However, the exact mechanism of ?-syn transmission also remains unclear. Therefore, in this study, we are trying to explore physiological roles of ?-syn and molecular mechanisms for the cell-to-cell ?-syn transmission. To understand novel roles of ?-syn in the nervous system functions, we expressed human ?-syn tagged with GFP specifically in the ASER sensory neuron, which responds to NaCl concentration changes. First, we examined the effect on morphology of the neuron, and found that both WT and A53T ?-syn expression increased several morphological changes such as cell-body branching and dendrite blebbing compared to the controls. Due to ?-syn accumulations as dot on the axon, we examined whether ?-syn affects synapse formation or vesicle trafficking. No significant difference was observed in synapse formation itself between control and ?-syn expressing worms. However, larger synaptic vesicle clusters on the axon was observed in ?-syn worms compared to that in the wild-type animals. These results suggest that ?-syn does not affect synapse formation in ASER but promote the accumulation of synaptic vesicles at release sites. Simultaneously, we examined the effects of ?-syn on neuronal activity by using calcium imaging. We found that ?-syn induced a significant lower Ca2+ response to the stimulus, and a slower Ca2+ influx and efflux at stimulus input, compared to responses in control animals. We are now trying to identify molecules which are affected by ?-syn, for the regulation of Ca2+ response in ASER. We hope that our analyses will identify the physiological functions of ?-syn and the molecular mechanism for its transmission through synapses.

Huynh VA et al. (2023) Front Cell Infect Microbiol "Desulfovibrio bacteria enhance alpha-synuclein aggregation in a Caenorhabditis elegans model of Parkinson's disease."

Murros KE, Takala TM, Huynh VA, Saris PEJ, Diwedi B

[Front Cell Infect Microbiol, 2023]

INTRODUCTION: bacteria induce alpha-syn aggregation. METHODS: bacteria on the survival of the nematodes. RESULTS AND DISCUSSION: bacteria contribute to PD development by inducing alpha-syn aggregation.

Qiao L et al. (2008) Mol Brain "Lysosomal enzyme cathepsin D protects against alpha-synuclein aggregation and toxicity."

Crimmins S, Roth KA, Speake LD, Lu Y, Wilson S, Liang Q, Parks R, Qiao L, Hamamichi S, Schneider L, Caldwell GA, Peng L, Iwatsubo T, Zhang J, Zhou Y, Standaert DG, Caldwell KA, Crabtree D, Shacka JJ, Xie ZL, Yacoubian TA, Walls KC, Uchiyama Y

[Mol Brain, 2008]

-synuclein (-syn) is a main component of Lewy bodies (LB) that occur in many neurodegenerative diseases, including Parkinson's disease (PD), dementia with LB (DLB) and multi-system atrophy. -syn mutations or amplifications are responsible for a subset of autosomal dominant familial PD cases, and overexpression causes neurodegeneration and motor disturbances in animals. To investigate mechanisms for -syn accumulation and toxicity, we studied a mouse model of lysosomal enzyme cathepsin D (CD) deficiency, and found extensive accumulation of endogenous -syn in neurons without overabundance of -syn mRNA. In addition to impaired macroautophagy, CD deficiency reduced proteasome activity, suggesting an essential role for lysosomal CD function in regulating multiple proteolytic pathways that are important for -syn metabolism. Conversely, CD overexpression reduces -syn aggregation and is neuroprotective against -syn overexpression-induced cell death in vitro. In a C. elegans model, CD deficiency exacerbates -syn accumulation while its overexpression is protective against -syn-induced dopaminergic neurodegeneration. Mutated CD with diminished enzymatic activity or overexpression of cathepsins B (CB) or L (CL) is not protective in the worm model, indicating a unique requirement for enzymatically active CD. Our data identify a conserved CD function in -syn degradation and identify CD as a novel target for LB disease therapeutics.

Ulamec SM et al. (2022) Nat Commun "Single residue modulators of amyloid formation in the N-terminal P1-region of α-synuclein"

van Oosten Hawle P, Radford SE, Dewison KM, Willis LF, Xu Y, Heath GR, Byrd EJ, Sobott F, Brockwell DJ, Ulamec SM, Maya-Martinez R, Buchman VL

[Nat Commun, 2022]

Alpha-synuclein (αSyn) is a protein involved in neurodegenerative disorders including Parkinson's disease. Amyloid formation of αSyn can be modulated by the 'P1 region' (residues 36-42). Here, mutational studies of P1 reveal that Y39A and S42A extend the lag-phase of αSyn amyloid formation in vitro and rescue amyloid-associated cytotoxicity in C. elegans. Additionally, L38I αSyn forms amyloid fibrils more rapidly than WT, L38A has no effect, but L38M does not form amyloid fibrils in vitro and protects from proteotoxicity. Swapping the sequence of the two residues that differ in the P1 region of the paralogue γSyn to those of αSyn did not enhance fibril formation for γSyn. Peptide binding experiments using NMR showed that P1 synergises with residues in the NAC and C-terminal regions to initiate aggregation. The remarkable specificity of the interactions that control αSyn amyloid formation, identifies this region as a potential target for therapeutics, despite their weak and transient nature.

Pena-Diaz S et al. (2019) Front Mol Neurosci "ZPD-2, a Small Compound That Inhibits -Synuclein Amyloid Aggregation and Its Seeded Polymerization."

Salvatella X, Carija A, Conde-Gimenez M, Santos J, Pena-Diaz S, Pujols J, Dalfo E, Ventura S, Pinheiro F, Garcia J, Sancho J, Navarro S

[Front Mol Neurosci, 2019]

-Synuclein (-Syn) forms toxic intracellular protein inclusions and transmissible amyloid structures in Parkinson's disease (PD). Preventing -Syn self-assembly has become one of the most promising approaches in the search for disease-modifying treatments for this neurodegenerative disorder. Here, we describe the capacity of a small molecule (ZPD-2), identified after a high-throughput screening, to inhibit -Syn aggregation. ZPD-2 inhibits the aggregation of <i>wild-type</i> -Syn and the A30P and H50Q familial variants <i>in vitro</i> at substoichiometric compound:protein ratios. In addition, the molecule prevents the spreading of -Syn seeds in protein misfolding cyclic amplification assays. ZPD-2 is active against different -Syn strains and blocks their seeded polymerization. Treating with ZPD-2 two different PD <i>Caenorhabditis elegans</i> models that express -Syn either in muscle or in dopaminergic (DA) neurons substantially reduces the number of -Syn inclusions and decreases synuclein-induced DA neurons degeneration. Overall, ZPD-2 is a hit compound worth to be explored in order to develop lead molecules for therapeutic intervention in PD.

Su LJ et al. (2010) Dis Model Mech "Compounds from an unbiased chemical screen reverse both ER-to-Golgi trafficking defects and mitochondrial dysfunction in Parkinson's disease models."

Cooper AA, Liu F, Kritzer JA, Fraenkel E, Rochet JC, Hill KJ, Tardiff DF, Bell GW, Hamamichi S, McCaffery JM, Caldwell GA, Strathearn KE, Caldwell KA, Lindquist S, Cao S, Outeiro TF, Yeger-Lotem E, Su LJ, Auluck PK

[Dis Model Mech, 2010]

alpha-Synuclein (alpha-syn) is a small lipid-binding protein involved in vesicle trafficking whose function is poorly characterized. It is of great interest to human biology and medicine because alpha-syn dysfunction is associated with several neurodegenerative disorders, including Parkinson''s disease (PD). We previously created a yeast model of alpha-syn pathobiology, which established vesicle trafficking as a process that is particularly sensitive to alpha-syn expression. We also uncovered a core group of proteins with diverse activities related to alpha-syn toxicity that is conserved from yeast to mammalian neurons. Here, we report that a yeast strain expressing a somewhat higher level of alpha-syn also exhibits strong defects in mitochondrial function. Unlike our previous strain, genetic suppression of endoplasmic reticulum (ER)-to-Golgi trafficking alone does not suppress alpha-syn toxicity in this strain. In an effort to identify individual compounds that could simultaneously rescue these apparently disparate pathological effects of alpha-syn, we screened a library of 115,000 compounds. We identified a class of small molecules that reduced alpha-syn toxicity at micromolar concentrations in this higher toxicity strain. These compounds reduced the formation of alpha-syn foci, re-established ER-to-Golgi trafficking and ameliorated alpha-syn-mediated damage to mitochondria. They also corrected the toxicity of alpha-syn in nematode neurons and in primary rat neuronal midbrain cultures. Remarkably, the compounds also protected neurons against rotenone-induced toxicity, which has been used to model the mitochondrial defects associated with PD in humans. That single compounds are capable of rescuing the diverse toxicities of alpha-syn in yeast and neurons suggests that they are acting on deeply rooted biological processes that connect these toxicities and have been conserved for a billion years of eukaryotic evolution. Thus, it seems possible to develop novel therapeutic strategies to simultaneously target the multiple pathological features of PD.

Tyson T et al. (2017) Sci Rep "Novel animal model defines genetic contributions for neuron-to-neuron transfer of -synuclein."

Brundin P, Van Raamsdonk JM, Tyson T, Senchuk M, Cooper JF, George S

[Sci Rep, 2017]

Cell-to-cell spreading of misfolded -synuclein (-syn) is suggested to contribute to the progression of neuropathology in Parkinson's disease (PD). Compelling evidence supports the hypothesis that misfolded -syn transmits from neuron-to-neuron and seeds aggregation of the protein in the recipient cells. Furthermore, -syn frequently appears to propagate in the brains of PD patients following a stereotypic pattern consistent with progressive spreading along anatomical pathways. We have generated a C. elegans model that mirrors this progression and allows us to monitor -syn neuron-to-neuron transmission in a live animal over its lifespan. We found that modulation of autophagy or exo/endocytosis, affects -syn transfer. Furthermore, we demonstrate that silencing C. elegans orthologs of PD-related genes also increases the accumulation of -syn. This novel worm model is ideal for screening molecules and genes to identify those that modulate prion-like spreading of -syn in order to target novel strategies for disease modification in PD and other synucleinopathies.

Doherty CPA et al. (2020) Nat Struct Mol Biol "A short motif in the N-terminal region of -synuclein is critical for both aggregation and function."

Brockwell DJ, Doherty CPA, Ulamec SM, Maya-Martinez R, Good SC, Radford SE, Makepeace J, Khan GN, van Oosten-Hawle P

[Nat Struct Mol Biol, 2020]

Aggregation of human -synuclein (Syn) is linked to Parkinson's disease (PD) pathology. The central region of the Syn sequence contains the non-amyloid -component (NAC) crucial for aggregation. However, how NAC flanking regions modulate Syn aggregation remains unclear. Using bioinformatics, mutation and NMR, we identify a 7-residue sequence, named P1 (residues 36-42), that controls Syn aggregation. Deletion or substitution of this 'master controller' prevents aggregation at pH 7.5 in vitro. At lower pH, P1 synergises with a sequence containing the preNAC region (P2, residues 45-57) to prevent aggregation. Deleting P1 (P1) or both P1 and P2 () also prevents age-dependent Syn aggregation and toxicity in C. elegans models and prevents Syn-mediated vesicle fusion by altering the conformational properties of the protein when lipid bound. The results highlight the importance of a master-controller sequence motif that controls both Syn aggregation and function-a region that could be targeted to prevent aggregation in disease.

Gitler AD et al. (2008) Proc Natl Acad Sci U S A "The Parkinson's disease protein alpha-synuclein disrupts cellular Rab homeostasis."

Barlowe C, Bevis BJ, Lindquist S, Gitler AD, Caldwell KA, McCaffery JM, Rochet JC, Shorter J, Su LJ, Strathearn KE, Hamamichi S, Caldwell GA

[Proc Natl Acad Sci U S A, 2008]

alpha-Synuclein (alpha-syn), a protein of unknown function, is the most abundant protein in Lewy bodies, the histological hallmark of Parkinson''s disease (PD). In yeast alpha-syn inhibits endoplasmic reticulum (ER)-to-Golgi (ER--&gt;Golgi) vesicle trafficking, which is rescued by overexpression of a Rab GTPase that regulates ER--&gt;Golgi trafficking. The homologous Rab1 rescues alpha-syn toxicity in dopaminergic neuronal models of PD. Here we investigate this conserved feature of alpha-syn pathobiology. In a cell-free system with purified transport factors alpha-syn inhibited ER--&gt;Golgi trafficking in an alpha-syn dose-dependent manner. Vesicles budded efficiently from the ER, but their docking or fusion to Golgi membranes was inhibited. Thus, the in vivo trafficking problem is due to a direct effect of alpha-syn on the transport machinery. By ultrastructural analysis the earliest in vivo defect was an accumulation of morphologically undocked vesicles, starting near the plasma membrane and growing into massive intracellular vesicular clusters in a dose-dependent manner. By immunofluorescence/immunoelectron microscopy, these clusters were associated both with alpha-syn and with diverse vesicle markers, suggesting that alpha-syn can impair multiple trafficking steps. Other Rabs did not ameliorate alpha-syn toxicity in yeast, but RAB3A, which is highly expressed in neurons and localized to presynaptic termini, and RAB8A, which is localized to post-Golgi vesicles, suppressed toxicity in neuronal models of PD. Thus, alpha-syn causes general defects in vesicle trafficking, to which dopaminergic neurons are especially sensitive.

Gitler AD et al. (2009) Nat Genet "Alpha-synuclein is part of a diverse and highly conserved interaction network that includes PARK9 and manganese toxicity."

Hamamichi S, Caldwell KA, Lindquist S, Gitler AD, Geddie ML, Strathearn KE, Cooper AA, Chesi A, Hill KJ, Rochet JC, Caldwell GA

[Nat Genet, 2009]

Parkinson''s disease (PD), dementia with Lewy bodies and multiple system atrophy, collectively referred to as synucleinopathies, are associated with a diverse group of genetic and environmental susceptibilities. The best studied of these is PD. alpha-Synuclein (alpha-syn) has a key role in the pathogenesis of both familial and sporadic PD, but evidence linking it to other predisposition factors is limited. Here we report a strong genetic interaction between alpha-syn and the yeast ortholog of the PD-linked gene ATP13A2 (also known as PARK9). Dopaminergic neuron loss caused by alpha-syn overexpression in animal and neuronal PD models is rescued by coexpression of PARK9. Further, knockdown of the ATP13A2 ortholog in Caenorhabditis elegans enhances alpha-syn misfolding. These data provide a direct functional connection between alpha-syn and another PD susceptibility locus. Manganese exposure is an environmental risk factor linked to PD and PD-like syndromes. We discovered that yeast PARK9 helps to protect cells from manganese toxicity, revealing a connection between PD genetics (alpha-syn and PARK9) and an environmental risk factor (PARK9 and manganese). Finally, we show that additional genes from our yeast screen, with diverse functions, are potent modifiers of alpha-syn-induced neuron loss in animals, establishing a diverse, highly conserved interaction network for alpha-syn.