scholarly journals Complex Network-Driven View of Genomic Mechanisms Underlying Parkinson’s Disease: Analyses in Dorsal Motor Vagal Nucleus, Locus Coeruleus, and Substantia Nigra

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Beatriz Raposo Corradini ◽  
Priscila Iamashita ◽  
Edilaine Tampellini ◽  
José Marcelo Farfel ◽  
Lea Tenenholz Grinberg ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Locus Coeruleus ◽  
Molecular Mechanisms ◽  
Brain Regions ◽  
Substantia Nigra Pars Compacta ◽  
Gene Sets ◽  
Coexpression Networks ◽  
Ageing Brain

Parkinson’s disease (PD)—classically characterized by severe loss of dopaminergic neurons in the substantia nigra pars compacta—has a caudal-rostral progression, beginning in the dorsal motor vagal nucleus and, in a less extent, in the olfactory system, progressing to the midbrain and eventually to the basal forebrain and the neocortex. About 90% of the cases are idiopathic. To study the molecular mechanisms involved in idiopathic PD we conducted a comparative study of transcriptional interaction networks in the dorsal motor vagal nucleus (VA), locus coeruleus (LC), and substantia nigra (SN) of idiopathic PD in Braak stages 4-5 (PD) and disease-free controls (CT) using postmortem samples. Gene coexpression networks (GCNs) for each brain region (patients and controls) were obtained to identify highly connected relevant genes (hubs) and densely interconnected gene sets (modules). GCN analyses showed differences in topology and module composition between CT and PD networks for each anatomic region. In CT networks, VA, LC, and SN hub modules are predominantly associated with neuroprotection and homeostasis in the ageing brain, whereas in the patient’s group, for the three brain regions, hub modules are mostly related to stress response and neuron survival/degeneration mechanisms.

scholarly journals Pronounced α-synuclein pathology in a seeding-based mouse model is not sufficient to induce mitochondrial respiration deficits in the striatum and amygdala

2020 ◽  
Author(s):  
Johannes Burtscher ◽  
Jean-Christophe Copin ◽  
Carmen Sandi ◽  
Hilal A. Lashuel
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Respiration ◽  
Early Stage ◽  
Relevant Literature ◽  
Brain Regions ◽  
Substantia Nigra Pars Compacta ◽  
Ros Generation

AbstractIncreasing evidence suggests that crosstalk between α-synuclein pathology formation and mitochondrial dysfunctions plays a central role in the pathogenesis of Parkinson’s disease and related synucleinopathies. While mitochondrial dysfunction is a well-studied phenomenon in the substantia nigra, which is selectively vulnerable in Parkinson’s disease and some models thereof, less information is available in other brain regions that are also affected by synuclein pathology.Therefore, we sought to test the hypothesis that early α-synuclein pathology causes mitochondrial dysfunction, and that this effect might be exacerbated in conditions of increased vulnerability of affected brain regions, such as the amygdala.We combined a model of intracerebral α-synuclein pathology seeding with chronic glucocorticoid treatment modelling non-motor symptoms of Parkinson’s disease and affecting amygdala physiology. We measured mitochondrial respiration, ROS generation and protein abundance as well as α-synuclein pathology in male mice.Chronic corticosterone administration induced mitochondrial hyperactivity in the amygdala. Although injection of α-synuclein preformed fibrils into the striatum resulted in pronounced α-synuclein pathology in both striatum and amygdala, mitochondrial respiration in these brain regions was altered in neither chronic corticosterone nor control conditions.Our results suggest that early stage α-synuclein pathology does not influence mitochondrial respiration in the striatum and amygdala, even in corticosterone-induced respirational hyperactivity. We discuss our findings in light of relevant literature, warn of a potential publication bias and encourage scientist to report their negative results in the frame of this model.Significance statementWe provide evidence that early stage synucleinopathy by itself or in combination with exogenous corticosterone induced amygdala hyperactivity did not compromise mitochondrial respiration in the striatum and amygdala in one of the most commonly used models of synucleinopathies. These results may explain, why this model in the hands of many research groups does not elicit pronounced Parkinson’s disease like symptoms in the absence of mitochondrial dysfunction in brain regions strongly affected by synuclein pathology and involved in non-motor (amygdala) and motor (striatum) symptoms. Our findings call for rigorous investigation of the short- and long-term effects of α-synuclein pathology on mitochondrial function/dysfunction in this model, in particular in brain regions strongly affected by neurodegeneration such as the substantia nigra pars compacta.

scholarly journals VMAT2-Deficient Mice Display Nigral and Extranigral Pathology and Motor and Nonmotor Symptoms of Parkinson's Disease

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Tonya N. Taylor ◽  
W. Michael Caudle ◽  
Gary W. Miller
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Locus Coeruleus ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Nonmotor Symptoms ◽  
Dopamine System ◽  
Progressive Neurodegeneration ◽  
Deficient Mice

Dopamine is transported into synaptic vesicles by the vesicular monoamine transporter (VMAT2; SLC18A2). Disruption of dopamine storage has been hypothesized to damage the dopamine neurons that are lost in Parkinson's disease. By disrupting vesicular storage of dopamine and other monoamines, we have created a progressive mouse model of PD that exhibits catecholamine neuron loss in the substantia nigra pars compacta and locus coeruleus and motor and nonmotor symptoms. With a 95% reduction in VMAT2 expression, VMAT2-deficient animals have decreased motor function, progressive deficits in olfactory discrimination, shorter latency to behavioral signs of sleep, delayed gastric emptying, anxiety-like behaviors at younger ages, and a progressive depressive-like phenotype. Pathologically, the VMAT2-deficient mice display progressive neurodegeneration in the substantia nigra (SNpc), locus coeruleus (LC), and dorsal raphe (DR) coupled withα-synuclein accumulation. Taken together, these studies demonstrate that reduced vesicular storage of monoamines and the resulting disruption of the cytosolic environment may play a role in the pathogenesis of parkinsonian symptoms and neurodegeneration. The multisystem nature of the VMAT2-deficient mice may be useful in developing therapeutic strategies that go beyond the dopamine system.

scholarly journals Neuroinflammation and protein pathology in Parkinson’s disease dementia

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Antonina Kouli ◽  
Marta Camacho ◽  
Kieren Allinson ◽  
Caroline H. Williams-Gray
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
T Lymphocytes ◽  
Substantia Nigra ◽  
Amyloid Β ◽  
Brain Regions ◽  
Parkinson’S Disease Dementia ◽  
Activated Microglia ◽  
Cell Counts ◽  
The Brain

AbstractParkinson’s disease dementia is neuropathologically characterized by aggregates of α-synuclein (Lewy bodies) in limbic and neocortical areas of the brain with additional involvement of Alzheimer’s disease-type pathology. Whilst immune activation is well-described in Parkinson’s disease (PD), how it links to protein aggregation and its role in PD dementia has not been explored. We hypothesized that neuroinflammatory processes are a critical contributor to the pathology of PDD. To address this hypothesis, we examined 7 brain regions at postmortem from 17 PD patients with no dementia (PDND), 11 patients with PD dementia (PDD), and 14 age and sex-matched neurologically healthy controls. Digital quantification after immunohistochemical staining showed a significant increase in the severity of α-synuclein pathology in the hippocampus, entorhinal and occipitotemporal cortex of PDD compared to PDND cases. In contrast, there was no difference in either tau or amyloid-β pathology between the groups in any of the examined regions. Importantly, we found an increase in activated microglia in the amygdala of demented PD brains compared to controls which correlated significantly with the extent of α-synuclein pathology in this region. Significant infiltration of CD4+ T lymphocytes into the brain parenchyma was commonly observed in PDND and PDD cases compared to controls, in both the substantia nigra and the amygdala. Amongst PDND/PDD cases, CD4+ T cell counts in the amygdala correlated with activated microglia, α-synuclein and tau pathology. Upregulation of the pro-inflammatory cytokine interleukin 1β was also evident in the substantia nigra as well as the frontal cortex in PDND/PDD versus controls with a concomitant upregulation in Toll-like receptor 4 (TLR4) in these regions, as well as the amygdala. The evidence presented in this study show an increased immune response in limbic and cortical brain regions, including increased microglial activation, infiltration of T lymphocytes, upregulation of pro-inflammatory cytokines and TLR gene expression, which has not been previously reported in the postmortem PDD brain.

scholarly journals A pH-eQTL interaction at the RIT2-SYT4 Parkinson's disease risk locus in the substantia nigra

2020 ◽  
Author(s):  
Sejal Patel ◽  
Derek Howard ◽  
Leon French
Keyword(s):  
Gene Expression ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Human Brain ◽  
Disease Risk ◽  
Brain Regions ◽  
Dopamine Neurons ◽  
Postmortem Human Brain ◽  
Increased Risk

BACKGROUND: Parkinson's disease (PD) causes severe motor and cognitive disabilities that result from the progressive loss of dopamine neurons in the substantia nigra. The rs12456492 variant in the RIT2 gene has been repeatedly associated with increased risk for Parkinson's disease. From a transcriptomic perspective, a meta-analysis found that RIT2 gene expression is correlated with pH in the human brain. OBJECTIVE: To assess pH associations at the RIT2-SYT4 locus. METHODS: Linear models to examine two datasets that assayed rs12456492, gene expression, and pH in the postmortem human brain. RESULTS: Using the BrainEAC dataset, we replicate the positive correlation between RIT2 gene expression and pH in the human brain. Furthermore, we found that the relationship between expression and pH is influenced by rs12456492. When tested across ten brain regions, this interaction is specifically found in the substantia nigra. A similar association was found for the co-localized SYT4 gene. In addition, SYT4 associations are stronger in a combined model with both genes, and the SYT4 interaction appears to be specific to males. In the GTEx dataset, the pH associations involving rs12456492 and expression of either SYT4 and RIT2 was not seen. This null finding may be due to the short postmortem intervals (PMI) of the GTEx tissue samples. In the BrainEAC data, we tested the effect of PMI and only observed the interactions in the longer PMI samples. CONCLUSIONS: These previously unknown associations suggest novel mechanistic roles for rs12456492, RIT2, and SYT4 in the regulation of pH in the substantia nigra.

scholarly journals Molecular Mechanisms Underlying Synaptic and Axon Degeneration in Parkinson’s Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Nolwazi Z. Gcwensa ◽  
Drèson L. Russell ◽  
Rita M. Cowell ◽  
Laura A. Volpicelli-Daley
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
Disease Onset ◽  
Neuronal Cell ◽  
Rem Sleep Behavior Disorder ◽  
Dopamine Neurons ◽  
Neuronal Cell Body ◽  
Substantia Nigra Pars Compacta ◽  
Cognitive Changes

Parkinson’s disease (PD) is a progressive neurodegenerative disease that impairs movement as well as causing multiple other symptoms such as autonomic dysfunction, rapid eye movement (REM) sleep behavior disorder, hyposmia, and cognitive changes. Loss of dopamine neurons in the substantia nigra pars compacta (SNc) and loss of dopamine terminals in the striatum contribute to characteristic motor features. Although therapies ease the symptoms of PD, there are no treatments to slow its progression. Accumulating evidence suggests that synaptic impairments and axonal degeneration precede neuronal cell body loss. Early synaptic changes may be a target to prevent disease onset and slow progression. Imaging of PD patients with radioligands, post-mortem pathologic studies in sporadic PD patients, and animal models of PD demonstrate abnormalities in presynaptic terminals as well as postsynaptic dendritic spines. Dopaminergic and excitatory synapses are substantially reduced in PD, and whether other neuronal subtypes show synaptic defects remains relatively unexplored. Genetic studies implicate several genes that play a role at the synapse, providing additional support for synaptic dysfunction in PD. In this review article we: (1) provide evidence for synaptic defects occurring in PD before neuron death; (2) describe the main genes implicated in PD that could contribute to synapse dysfunction; and (3) show correlations between the expression of Snca mRNA and mouse homologs of PD GWAS genes demonstrating selective enrichment of Snca and synaptic genes in dopaminergic, excitatory and cholinergic neurons. Altogether, these findings highlight the need for novel therapeutics targeting the synapse and suggest that future studies should explore the roles for PD-implicated genes across multiple neuron types and circuits.

scholarly journals Explorative Combined Lipid and Transcriptomic Profiling of Substantia Nigra and Putamen in Parkinson’s Disease

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1966 ◽  
Author(s):  
Helena Xicoy ◽  
Jos F. Brouwers ◽  
Bé Wieringa ◽  
Gerard J. M. Martens
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Molecular Mechanisms ◽  
Lipid Analysis ◽  
Dorsal Striatum ◽  
Receptor Subtype ◽  
Lipid Profiling ◽  
New Genes ◽  
Genes Encoding

Parkinson’s disease (PD) is characterized by the loss of dopaminergic neurons from the substantia nigra (SN) that project to the dorsal striatum (caudate-putamen). To better understand the molecular mechanisms underlying PD, we performed combined lipid profiling and RNA sequencing of SN and putamen samples from PD patients and age-matched controls. SN lipid analysis pointed to a neuroinflammatory component and included elevated levels of the endosomal lipid Bis (Monoacylglycero)Phosphate 42:8, while two of the three depleted putamen lipids were saturated sphingomyelin species. Remarkably, we observed gender-related differences in the SN and putamen lipid profiles. Transcriptome analysis revealed that the top-enriched pathways among the 354 differentially expressed genes (DEGs) in the SN were “protein folding” and “neurotransmitter transport”, and among the 261 DEGs from putamen “synapse organization”. Furthermore, we identified pathways, e.g., “glutamate signaling”, and genes, encoding, e.g., an angiotensin receptor subtype or a proprotein convertase, that have not been previously linked to PD. The identification of 33 genes that were common among the SN and putamen DEGs, which included the α-synuclein paralog β-synuclein, may contribute to the understanding of general PD mechanisms. Thus, our proof-of-concept data highlights new genes, pathways and lipids that have not been explored before in the context of PD.

scholarly journals Proteomic Characterization of Synaptosomes from Human Substantia Nigra Indicates Altered Mitochondrial Translation in Parkinson’s Disease

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2580
Author(s):  
Sarah Plum ◽  
Britta Eggers ◽  
Stefan Helling ◽  
Markus Stepath ◽  
Carsten Theiss ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Gradient Centrifugation ◽  
Synaptic Function ◽  
Substantia Nigra Pars Compacta ◽  
Differential Analysis ◽  
Mitochondrial Translation ◽  
Control Subjects ◽  
Core Proteome

The pathological hallmark of Parkinson’s disease (PD) is the loss of neuromelanin-containing dopaminergic neurons within the substantia nigra pars compacta (SNpc). Additionally, numerous studies indicate an altered synaptic function during disease progression. To gain new insights into the molecular processes underlying the alteration of synaptic function in PD, a proteomic study was performed. Therefore, synaptosomes were isolated by density gradient centrifugation from SNpc tissue of individuals at advanced PD stages (N = 5) as well as control subjects free of pathology (N = 5) followed by mass spectrometry-based analysis. In total, 362 proteins were identified and assigned to the synaptosomal core proteome. This core proteome comprised all proteins expressed within the synapses without regard to data analysis software, gender, age, or disease. The differential analysis between control subjects and PD cases revealed that CD9 antigen was overrepresented and fourteen proteins, among them Thymidine kinase 2 (TK2), mitochondrial, 39S ribosomal protein L37, neurolysin, and Methionine-tRNA ligase (MARS2) were underrepresented in PD suggesting an alteration in mitochondrial translation within synaptosomes.

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