-
Nature Communications Aug 2020We describe a human single-nuclei transcriptomic atlas for the substantia nigra (SN), generated by sequencing approximately 17,000 nuclei from matched cortical and SN...
We describe a human single-nuclei transcriptomic atlas for the substantia nigra (SN), generated by sequencing approximately 17,000 nuclei from matched cortical and SN samples. We show that the common genetic risk for Parkinson's disease (PD) is associated with dopaminergic neuron (DaN)-specific gene expression, including mitochondrial functioning, protein folding and ubiquitination pathways. We identify a distinct cell type association between PD risk and oligodendrocyte-specific gene expression. Unlike Alzheimer's disease (AD), we find no association between PD risk and microglia or astrocytes, suggesting that neuroinflammation plays a less causal role in PD than AD. Beyond PD, we find associations between SN DaNs and GABAergic neuron gene expression and multiple neuropsychiatric disorders. Conditional analysis reveals that distinct neuropsychiatric disorders associate with distinct sets of neuron-specific genes but converge onto shared loci within oligodendrocytes and oligodendrocyte precursors. This atlas guides our aetiological understanding by associating SN cell type expression profiles with specific disease risk.
Topics: Alzheimer Disease; Astrocytes; Brain; Dopaminergic Neurons; Gene Expression; Humans; Microglia; Mitochondria; Nervous System Diseases; Parkinson Disease; Substantia Nigra; Transcriptome
PubMed: 32826893
DOI: 10.1038/s41467-020-17876-0 -
Journal of Neuroinflammation Dec 2019Metabolic dysfunction and neuroinflammation are increasingly implicated in Parkinson's disease (PD). The pentose phosphate pathway (PPP, a metabolic pathway parallel to...
BACKGROUND
Metabolic dysfunction and neuroinflammation are increasingly implicated in Parkinson's disease (PD). The pentose phosphate pathway (PPP, a metabolic pathway parallel to glycolysis) converts glucose-6-phosphate into pentoses and generates ribose-5-phosphate and NADPH thereby governing anabolic biosynthesis and redox homeostasis. Brains and immune cells display high activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP. A postmortem study reveals dysregulation of G6PD enzyme in brains of PD patients. However, spatial and temporal changes in activity/expression of G6PD in PD remain undetermined. More importantly, it is unclear how dysfunction of G6PD and the PPP affects neuroinflammation and neurodegeneration in PD.
METHODS
We examined expression/activity of G6PD and its association with microglial activation and dopaminergic neurodegeneration in multiple chronic PD models generated by an intranigral/intraperitoneal injection of LPS, daily subcutaneous injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 6 days, or transgenic expression of A53T α-synuclein. Primary microglia were transfected with G6PD siRNAs and treated with lipopolysaccharide (LPS) to examine effects of G6PD knockdown on microglial activation and death of co-cultured neurons. LPS alone or with G6PD inhibitor(s) was administrated to mouse substantia nigra or midbrain neuron-glia cultures. While histological and biochemical analyses were conducted to examine microglial activation and dopaminergic neurodegeneration in vitro and in vivo, rotarod behavior test was performed to evaluate locomotor impairment in mice.
RESULTS
Expression and activity of G6PD were elevated in LPS-treated midbrain neuron-glia cultures (an in vitro PD model) and the substantia nigra of four in vivo PD models. Such elevation was positively associated with microglial activation and dopaminergic neurodegeneration. Furthermore, inhibition of G6PD by 6-aminonicotinamide and dehydroepiandrosterone and knockdown of microglial G6PD attenuated LPS-elicited chronic dopaminergic neurodegeneration. Mechanistically, microglia with elevated G6PD activity/expression produced excessive NADPH and provided abundant substrate to over-activated NADPH oxidase (NOX2) leading to production of excessive reactive oxygen species (ROS). Knockdown and inhibition of G6PD ameliorated LPS-triggered production of ROS and activation of NF-кB thereby dampening microglial activation.
CONCLUSIONS
Our findings indicated that G6PD-mediated PPP dysfunction and neuroinflammation exacerbated each other mediating chronic dopaminergic neurodegeneration and locomotor impairment. Insight into metabolic-inflammatory interface suggests that G6PD and NOX2 are potential therapeutic targets for PD.
Topics: Animals; Cells, Cultured; Coculture Techniques; Dopaminergic Neurons; Female; Gene Knockdown Techniques; Inflammation; Inflammation Mediators; Mice; Mice, Inbred C57BL; Nerve Degeneration; Pentose Phosphate Pathway; Pregnancy; Rats; Rats, Inbred F344; Reactive Oxygen Species
PubMed: 31805953
DOI: 10.1186/s12974-019-1659-1 -
Nature Methods Dec 2023Ventral midbrain dopaminergic neurons project to the striatum as well as the cortex and are involved in movement control and reward-related cognition. In Parkinson's...
Ventral midbrain dopaminergic neurons project to the striatum as well as the cortex and are involved in movement control and reward-related cognition. In Parkinson's disease, nigrostriatal midbrain dopaminergic neurons degenerate and cause typical Parkinson's disease motor-related impairments, while the dysfunction of mesocorticolimbic midbrain dopaminergic neurons is implicated in addiction and neuropsychiatric disorders. Study of the development and selective neurodegeneration of the human dopaminergic system, however, has been limited due to the lack of an appropriate model and access to human material. Here, we have developed a human in vitro model that recapitulates key aspects of dopaminergic innervation of the striatum and cortex. These spatially arranged ventral midbrain-striatum-cortical organoids (MISCOs) can be used to study dopaminergic neuron maturation, innervation and function with implications for cell therapy and addiction research. We detail protocols for growing ventral midbrain, striatal and cortical organoids and describe how they fuse in a linear manner when placed in custom embedding molds. We report the formation of functional long-range dopaminergic connections to striatal and cortical tissues in MISCOs, and show that injected, ventral midbrain-patterned progenitors can mature and innervate the tissue. Using these assembloids, we examine dopaminergic circuit perturbations and show that chronic cocaine treatment causes long-lasting morphological, functional and transcriptional changes that persist upon drug withdrawal. Thus, our method opens new avenues to investigate human dopaminergic cell transplantation and circuitry reconstruction as well as the effect of drugs on the human dopaminergic system.
Topics: Humans; Parkinson Disease; Mesencephalon; Dopamine; Dopaminergic Neurons; Corpus Striatum
PubMed: 38052989
DOI: 10.1038/s41592-023-02080-x -
Nature Neuroscience Jan 2022Social interactions are motivated behaviors that, in many species, facilitate learning. However, how the brain encodes the reinforcing properties of social interactions...
Social interactions are motivated behaviors that, in many species, facilitate learning. However, how the brain encodes the reinforcing properties of social interactions remains unclear. In this study, using in vivo recording in freely moving mice, we show that dopamine (DA) neurons of the ventral tegmental area (VTA) increase their activity during interactions with an unfamiliar conspecific and display heterogeneous responses. Using a social instrumental task, we then show that VTA DA neuron activity encodes social prediction error and drives social reinforcement learning. Thus, our findings suggest that VTA DA neurons are a neural substrate for a social learning signal that drives motivated behavior.
Topics: Animals; Dopaminergic Neurons; Mice; Reinforcement, Psychology; Reward; Social Interaction; Ventral Tegmental Area
PubMed: 34857949
DOI: 10.1038/s41593-021-00972-9 -
Neuron Aug 2021Nicotine stimulates dopamine (DA) neurons of the ventral tegmental area (VTA) to establish and maintain reinforcement. Nicotine also induces anxiety through an as yet...
Nicotine stimulates dopamine (DA) neurons of the ventral tegmental area (VTA) to establish and maintain reinforcement. Nicotine also induces anxiety through an as yet unknown circuitry. We found that nicotine injection drives opposite functional responses of two distinct populations of VTA DA neurons with anatomically segregated projections: it activates neurons that project to the nucleus accumbens (NAc), whereas it inhibits neurons that project to the amygdala nuclei (Amg). We further show that nicotine mediates anxiety-like behavior by acting on β2-subunit-containing nicotinic acetylcholine receptors of the VTA. Finally, using optogenetics, we bidirectionally manipulate the VTA-NAc and VTA-Amg pathways to dissociate their contributions to anxiety-like behavior. We show that inhibition of VTA-Amg DA neurons mediates anxiety-like behavior, while their activation prevents the anxiogenic effects of nicotine. These distinct subpopulations of VTA DA neurons with opposite responses to nicotine may differentially drive the anxiogenic and the reinforcing effects of nicotine.
Topics: Amygdala; Animals; Anxiety; Dopamine; Dopaminergic Neurons; Male; Mice; Neural Pathways; Nicotine; Nicotinic Agonists; Nucleus Accumbens; Receptors, Nicotinic; Reinforcement, Psychology; Ventral Tegmental Area
PubMed: 34242565
DOI: 10.1016/j.neuron.2021.06.013 -
ELife Jun 2022New findings cast doubt on whether suppressing the RNA-binding protein PTBP1 can force astrocytes to become dopaminergic neurons.
New findings cast doubt on whether suppressing the RNA-binding protein PTBP1 can force astrocytes to become dopaminergic neurons.
Topics: Astrocytes; Cells, Cultured; Dopaminergic Neurons; Gatekeeping
PubMed: 35723428
DOI: 10.7554/eLife.80232 -
Frontiers in Immunology 2021Neuroinflammation and mitochondrial impairment play important roles in the neuropathogenesis of Parkinson's disease (PD). The activation of NLRP3 inflammasome and the...
BACKGROUND
Neuroinflammation and mitochondrial impairment play important roles in the neuropathogenesis of Parkinson's disease (PD). The activation of NLRP3 inflammasome and the accumulation of α-synuclein (α-Syn) are strictly correlated to neuroinflammation. Therefore, the regulation of NLRP3 inflammasome activation and α-Syn aggregation might have therapeutic potential. It has been indicated that Dl-3-n-butylphthalide (NBP) produces neuroprotection against some neurological diseases such as ischemic stroke. We here intended to explore whether NBP suppressed NLRP3 inflammasome activation and reduced α-Syn aggregation, thus protecting dopaminergic neurons against neuroinflammation.
METHODS
In our study, we established a MPTP-induced mouse model and 6-OHDA-induced SH-SY5Y cell model to examine the neuroprotective actions of NBP. We then performed behavioral tests to examine motor dysfunction in MPTP-exposed mice after NBP treatment. Western blotting, immunofluorescence staining, flow cytometry and RT-qPCR were conducted to investigate the expression of NLRP3 inflammasomes, neuroinflammatory cytokines, PARP1, p-α-Syn, and markers of microgliosis and astrogliosis.
RESULTS
The results showed that NBP exerts a neuroprotective effect on experimental PD models. , NBP ameliorated behavioral impairments and reduced dopaminergic neuron loss in MPTP-induced mice. , treatment of SH-SY5Y cells with 6-OHDA (100uM,24 h) significantly decreased cell viability, increased intracellular ROS production, and induced apoptosis, while pretreatment with 5uM NBP could alleviated 6-OHDA-induced cytotoxicity, ROS production and cell apoptosis to some extent. Importantly, both and , NBP suppressed the activation of the NLRP3 inflammasome and the aggregation of α-Syn, thus inhibited neuroinflammation ameliorated mitochondrial impairments.
CONCLUSIONS
In summary, NBP rescued dopaminergic neurons by reducing NLRP3 inflammasome activation and ameliorating mitochondrial impairments and increases in p-α-Syn levels. This current study may provide novel neuroprotective mechanisms of NBP as a potential therapeutic agent.
Topics: Animals; Apoptosis; Benzofurans; Cell Line; Disease Models, Animal; Dopaminergic Neurons; Humans; Inflammasomes; Mice; Mitochondria; NLR Family, Pyrin Domain-Containing 3 Protein; Neuroprotective Agents; Parkinson Disease; Protein Aggregation, Pathological; alpha-Synuclein
PubMed: 34925379
DOI: 10.3389/fimmu.2021.794770 -
Nature Communications May 2023Parkinson's disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative...
Parkinson's disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative epidemiologic study of pesticide exposures and PD with toxicity screening in dopaminergic neurons derived from PD patient induced pluripotent stem cells (iPSCs) to identify Parkinson's-relevant pesticides. Agricultural records enable investigation of 288 specific pesticides and PD risk in a comprehensive, pesticide-wide association study. We associate long-term exposure to 53 pesticides with PD and identify co-exposure profiles. We then employ a live-cell imaging screening paradigm exposing dopaminergic neurons to 39 PD-associated pesticides. We find that 10 pesticides are directly toxic to these neurons. Further, we analyze pesticides typically used in combinations in cotton farming, demonstrating that co-exposures result in greater toxicity than any single pesticide. We find trifluralin is a driver of toxicity to dopaminergic neurons and leads to mitochondrial dysfunction. Our paradigm may prove useful to mechanistically dissect pesticide exposures implicated in PD risk and guide agricultural policy.
Topics: Humans; Pesticides; Parkinson Disease; Induced Pluripotent Stem Cells; Neurodegenerative Diseases; Dopaminergic Neurons
PubMed: 37193692
DOI: 10.1038/s41467-023-38215-z -
Molecular Neurodegeneration Jan 2024Parkinson's Disease (PD) is the second most common neurodegenerative disorder. The pathological hallmark of PD is loss of dopaminergic neurons and the presence of...
Parkinson's Disease (PD) is the second most common neurodegenerative disorder. The pathological hallmark of PD is loss of dopaminergic neurons and the presence of aggregated α-synuclein, primarily in the substantia nigra pars compacta (SNpc) of the midbrain. However, the molecular mechanisms that underlie the pathology in different cell types is not currently understood. Here, we present a single nucleus transcriptome analysis of human post-mortem SNpc obtained from 15 sporadic Parkinson's Disease (PD) cases and 14 Controls. Our dataset comprises ∼84K nuclei, representing all major cell types of the brain, allowing us to obtain a transcriptome-level characterization of these cell types. Importantly, we identify multiple subpopulations for each cell type and describe specific gene sets that provide insights into the differing roles of these subpopulations. Our findings reveal a significant decrease in neuronal cells in PD samples, accompanied by an increase in glial cells and T cells. Subpopulation analyses demonstrate a significant depletion of tyrosine hydroxylase (TH) enriched astrocyte, microglia and oligodendrocyte populations in PD samples, as well as TH enriched neurons, which are also depleted. Moreover, marker gene analysis of the depleted subpopulations identified 28 overlapping genes, including those associated with dopamine metabolism (e.g., ALDH1A1, SLC6A3 & SLC18A2). Overall, our study provides a valuable resource for understanding the molecular mechanisms involved in dopaminergic neuron degeneration and glial responses in PD, highlighting the existence of novel subpopulations and cell type-specific gene sets.
Topics: Humans; Parkinson Disease; Mesencephalon; Dopaminergic Neurons; Substantia Nigra
PubMed: 38245794
DOI: 10.1186/s13024-023-00699-0 -
Cell Reports Oct 2020The advent of induced pluripotent stem cell (iPSC)-derived neurons has revolutionized Parkinson's disease (PD) research, but single-cell transcriptomic analysis suggests...
The advent of induced pluripotent stem cell (iPSC)-derived neurons has revolutionized Parkinson's disease (PD) research, but single-cell transcriptomic analysis suggests unresolved cellular heterogeneity within these models. Here, we perform the largest single-cell transcriptomic study of human iPSC-derived dopaminergic neurons to elucidate gene expression dynamics in response to cytotoxic and genetic stressors. We identify multiple neuronal subtypes with transcriptionally distinct profiles and differential sensitivity to stress, highlighting cellular heterogeneity in dopamine in vitro models. We validate this disease model by showing robust expression of PD GWAS genes and overlap with postmortem adult substantia nigra neurons. Importantly, stress signatures are ameliorated using felodipine, an FDA-approved drug. Using isogenic SNCA-A53T mutants, we find perturbations in glycolysis, cholesterol metabolism, synaptic signaling, and ubiquitin-proteasomal degradation. Overall, our study reveals cell type-specific perturbations in human dopamine neurons, which will further our understanding of PD and have implications for cell replacement therapies.
Topics: Cell Differentiation; Cell Respiration; Cholesterol; Chromatin Assembly and Disassembly; Dopaminergic Neurons; Down-Regulation; Endoplasmic Reticulum Stress; Gene Expression Profiling; Genome-Wide Association Study; Glycolysis; Humans; Induced Pluripotent Stem Cells; Models, Biological; Oxidative Phosphorylation; Oxidative Stress; Parkinson Disease; Proteasome Endopeptidase Complex; Regression Analysis; Signal Transduction; Single-Cell Analysis; Stress, Physiological; Synapses; Transcriptome; Ubiquitin; Up-Regulation
PubMed: 33053338
DOI: 10.1016/j.celrep.2020.108263