Project description:Cellular toxicities of alpha-synuclein manifest through multiple pathways, including mitochondrial dysfunction and the inhibition of vesicle trafficking. Several defects can be ameliorated by small molecule suppressors that antagonize toxicity in model systems ranging from yeast to neurons. Connections between these distinct pathologies may be central to Parkinson Disease and to therapeutic strategies. First, yeast cultures with 1 or 2 copies of human alpha-synuclein were profiled during a time series of 0 to 6 hours. Second, to investigate any potential rescue of alpha-synuclein toxicity, one of a series of six compounds: compound 1 ((4-(3-iodophenyl)-3,4-dihydrobenzo[h]quinolin-2(1H)-one); compound 2 (4-(3-bromophenyl)-3,4-dihydrobenzo[h]quinolin-2(1H)-one); compound 3 (4-(5-bromo-2-fluorophenyl)-6,7-dimethyl-3,4-dihydro-2(1H)-quinolinone); compound 4 (4-(3-bromo-4-fluorophenyl)-6,7-dimethyl-3,4-dihydro-2(1H)-quinolinone); compound 5 (4-(4-ethyl)-6,7-dimethyl-3,4-dihydro-2(1H)-quinolinone); compound 6 ((4R)-6-bromo-4-(4-ethylphenyl)-3,4-dihydrobenzo[h]quinolin-2(1H)-one); was introduced and the expression profile assayed at 4 hours.
Project description:We compared transcriptome profile of ITox2C strain expressing dCas9-VP64 (aka screen strain) that express gRNA 9-1 with those expressing no gRNA
Project description:The genome-wide perturbation of transcriptional networks with CRISPR-Cas technology has primarily involved systematic and targeted gene modulation. Here, we developed PRISM (Perturbing Regulatory Interactions by Synthetic Modulators), a screening platform that uses randomized CRISPR-Cas transcription factors (crisprTFs) to globally perturb transcriptional networks. By applying PRISM to a yeast model of Parkinson's disease (PD), we identified guide RNAs (gRNAs) that modulate transcriptional networks and protect cells from alpha-synuclein (αSyn) toxicity. One gRNA identified in this screen outperformed the most protective suppressors of αSyn toxicity reported previously, highlighting PRISM's ability to identify modulators of important phenotypes. Gene expression profiling revealed genes differentially modulated by this strong protective gRNA that rescued yeast from αSyn toxicity when overexpressed. Human homologs of top-ranked hits protected against αSyn-induced cell death in a human neuronal PD model. Thus, high-throughput and unbiased perturbation of transcriptional networks via randomized crisprTFs can reveal complex biological phenotypes and effective disease modulators.
Project description:While GM1 may interact with α-synuclein in vitro to inhibit aggregation, the ability of GM1 to protect against α-synuclein toxicity in vivo has not been investigated. We used targeted adeno-associated viral vector (AAV) overexpression of human mutant α-synuclein (A53T) in the rat substantia nigra (SN) to produce degeneration of SN dopamine neurons, loss of striatal dopamine levels, and behavioral impairment. Some animals received daily GM1 ganglioside administration for 6 weeks, beginning 24 hours after AAV-A53T administration or delayed start GM1 administration for 5 weeks beginning 3 weeks after AAV-A53T administration. Both types of GM1 administration protected against loss of SN dopamine neurons and striatal dopamine levels, reduced α-synuclein aggregation, and delayed start administration of GM1 reversed early appearing behavioral deficits. These results extend prior positive results in MPTP models, are consistent with the results of a small clinical study of GM1 in PD patients that showed slowing of symptom progression with chronic use, and argue for the continued refinement and development of GM1 as a potential disease modifying therapy for PD.
Project description:Idiopathic Parkinson's disease is the second most common neurodegenerative disease and is estimated to be approximately 30% heritable. Genome wide association studies have revealed numerous loci associated with risk of development of Parkinson's disease. The majority of genes identified in these studies are expressed in glia at either similar or greater levels than their expression in neurons, suggesting that glia may play a role in Parkinson's disease pathogenesis. The role of individual glial risk genes in Parkinson's disease development or progression is unknown, however. We hypothesized that some Parkinson's disease risk genes exert their effects through glia. We developed a Drosophila model of α-synucleinopathy in which we can independently manipulate gene expression in neurons and glia. Human wild type α-synuclein is expressed in all neurons, and these flies develop the hallmarks of Parkinson's disease, including motor impairment, death of dopaminergic and other neurons, and α-synuclein aggregation. In these flies, we performed a candidate genetic screen, using RNAi to knockdown 14 well-validated Parkinson's disease risk genes in glia and measuring the effect on locomotion in order to identify glial modifiers of the α-synuclein phenotype. We identified 4 modifiers: aux, Lrrk, Ric, and Vps13, orthologs of the human genes GAK, LRRK2, RIT2, and VPS13C, respectively. Knockdown of each gene exacerbated neurodegeneration as measured by total and dopaminergic neuron loss. Knockdown of each modifier also increased α-synuclein oligomerization. These results suggest that some Parkinson's disease risk genes exert their effects in glia and that glia can influence neuronal α-synuclein proteostasis in a non-cell-autonomous fashion. Further, this study provides proof of concept that our novel Drosophila α-synucleinopathy model can be used to study glial modifier genes, paving the way for future large unbiased screens to identify novel glial risk factors that contribute to PD risk and progression.
Project description:Parkinson's disease (PD) is the second most common neurodegenerative disease; it is characterized by the loss of dopaminergic neurons in the midbrain and the accumulation of neuronal inclusions, mainly consisting of α-synuclein (α-syn) fibrils in the affected regions. The prion-like property of the pathological forms of α-syn transmitted via neuronal circuits has been considered inherent in the nature of PD. Thus, one of the potential targets in terms of PD prevention is the suppression of α-syn conversion from the functional form to pathological forms. Recent studies suggested that α-syn interacts with synaptic vesicle membranes and modulate the synaptic functions. A series of studies suggest that transient interaction of α-syn as multimers with synaptic vesicle membranes composed of phospholipids and other lipids is required for its physiological function, while an α-syn-lipid interaction imbalance is believed to cause α-syn aggregation and the resultant pathological α-syn conversion. Altered lipid metabolisms have also been implicated in the modulation of PD pathogenesis. This review focuses on the current literature reporting the role of lipids, especially phospholipids, and lipid metabolism in α-syn dynamics and aggregation processes.
Project description:Parkinson's disease is a neurodegenerative disorder, characterized by accumulation and misfolding of α-synuclein. Although the level of α-synuclein in neurons is fundamentally linked to the onset of neurodegeneration, multiple pathways have been implicated in its degradation, and it remains unclear which are the critical ubiquitination enzymes that protect against α-synuclein accumulation in vivo. The ubiquitin ligase Nedd4 targets α-synuclein to the endosomal-lysosomal pathway in cultured cells. Here we asked whether Nedd4-mediated degradation protects against α-synuclein-induced toxicity in the Drosophila and rodent models of Parkinson's disease. We show that overexpression of Nedd4 can rescue the degenerative phenotype from ectopic expression of α-synuclein in the Drosophila eye. Overexpressed Nedd4 in the Drosophila brain prevented the α-synuclein-induced locomotor defect whereas reduction in endogenous Nedd4 by RNAi led to worsening motor function and increased loss of dopaminergic neurons. Accordingly, AAV-mediated expression of wild-type but not the catalytically inactive Nedd4 decreased the α-synuclein-induced dopaminergic cell loss in the rat substantia nigra and reduced α-synuclein accumulation. Collectively, our data in two evolutionarily distant model organisms strongly suggest that Nedd4 is a modifier of α-synuclein pathobiology and thus a potential target for neuroprotective therapies.
Project description:Whole gene duplications and triplications of alpha-synuclein (SNCA) can cause Parkinson's disease (PD), and variation in the promoter region (Rep1) and 3' region of SNCA has been reported to increase disease susceptibility. Within our cohort, one affected individual from each of 92 multiplex PD families showing the greatest evidence of linkage to the region around SNCA was screened for dosage alterations and sequence changes; no dosage or non-synonymous sequence changes were found. In addition, 737 individuals (from 450 multiplex PD families) that met strict diagnostic criteria for PD and did not harbor a known causative mutation, as well as 359 neurologically normal controls, were genotyped for the Rep1 polymorphism and four SNPs in the 3' region of SNCA. The four SNPs were in high LD (r(2) > 0.95) and were analyzed as a haplotype. The effects of the Rep1 genotype and the 3' haplotype were evaluated using regression models employing only one individual per family. Cases had a 3% higher frequency of the Rep1 263 bp allele compared with controls (OR = 1.54; empirical P-value = 0.02). There was an inverse linear relationship between the number of 263 bp alleles and age of onset (empirical P-value = 0.0004). The 3' haplotype was also associated with disease (OR = 1.29; empirical P-value = 0.01), but not age of onset (P = 0.40). These data suggest that dosage and sequence changes are a rare cause of PD, but variation in the promoter and 3' region of SNCA convey an increased risk for PD.
Project description:Parkinson's disease (PD), a neurodegenerative disorder characterized by distinct aging-independent loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) region urging toward neuronal loss. Over the decade, various key findings from clinical perspective to molecular pathogenesis have aided in understanding the genetics with assorted genes related with PD. Subsequently, several pathways have been incriminated in the pathogenesis of PD, involving mitochondrial dysfunction, protein aggregation, and misfolding. On the other hand, the sporadic form of PD cases is found with no genetic linkage, which still remain an unanswered question? The exertion in ascertaining vulnerability factors in PD considering the genetic factors are to be further dissevered in the forthcoming decades with advancement in research studies. One of the major proponents behind the prognosis of PD is the pathogenic transmutation of aberrant alpha-synuclein protein into amyloid fibrillar structures, which actuates neurodegeneration. Alpha-synuclein, transcribed by SNCA gene is a neuroprotein found predominantly in brain. It is implicated in the modulation of synaptic vesicle transport and eventual release of neurotransmitters. Due to genetic mutations and other elusive factors, the alpha-synuclein misfolds into its amyloid form. Therefore, this review aims in briefing the molecular understanding of the alpha-synuclein associated with PD.
Project description:Over the last decades, cerium oxide nanoparticles (CeO2 NPs) have gained great interest due to their potential applications, mainly in the fields of agriculture and biomedicine. Promising effects of CeO2 NPs are recently shown in some neurodegenerative diseases, but the mechanism of action of these NPs in Parkinson's disease (PD) remains to be investigated. This issue is addressed in the present study by using a yeast model based on the heterologous expression of the human α-synuclein (α-syn), the major component of Lewy bodies, which represent a neuropathological hallmark of PD. We observed that CeO2 NPs strongly reduce α-syn-induced toxicity in a dose-dependent manner. This effect is associated with the inhibition of cytoplasmic α-syn foci accumulation, resulting in plasma membrane localization of α-syn after NP treatment. Moreover, CeO2 NPs counteract the α-syn-induced mitochondrial dysfunction and decrease reactive oxygen species (ROS) production in yeast cells. In vitro binding assay using cell lysates showed that α-syn is adsorbed on the surface of CeO2 NPs, suggesting that these NPs may act as a strong inhibitor of α-syn toxicity not only acting as a radical scavenger, but through a direct interaction with α-syn in vivo.