Early alterations of mitochondrial morphology in dopaminergic neurons from Parkinson's disease-like pathology and time-dependent neuroprotection with D2 receptor activation

Background: Parkinson's Disease results from a loss of dopaminergic neurons, and reduced levels of the neurotransmitter dopamine. Parkinson's Disease treatments involve increasing dopamine levels through administration of L-DOPA, which can cross the blood brain barrier and be converted to dopamine in the brain. The toxicity of dopamine has previously studied but there has been little study of L-DOPA toxicity. Methods: We have compared the toxicity of dopamine and L-DOPA in the yeasts, Saccharomyces cerevisiae and Candida glabrata by cell viability assays, measuring colony forming units. Results: L-DOPA and dopamine caused time-dependent cell killing in Candida glabrata while only dopamine caused such effects in Saccharomyces cerevisiae. The toxicity of L-DOPA is much lower than dopamine. Conclusion: Candida glabrata exhibits high sensitivity to L-DOPA and may have advantages for studying the cytotoxicity of L-DOPA.

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α-Synuclein-induced dysregulation of neuronal activity contributes to murine dopamine neuron vulnerability

npj Parkinson s Disease ◽

10.1038/s41531-021-00210-w ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Abeer Dagra ◽

Douglas R. Miller ◽

Min Lin ◽

Adithya Gopinath ◽

Fatemeh Shaerzadeh ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Neuronal Activity ◽

Dopaminergic Neurons ◽

Prolonged Exposure ◽

D2 Receptor ◽

Neuronal Firing ◽

Dopamine Neurons ◽

Loss Of Function ◽

Therapeutic Implications

AbstractPathophysiological damages and loss of function of dopamine neurons precede their demise and contribute to the early phases of Parkinson’s disease. The presence of aberrant intracellular pathological inclusions of the protein α-synuclein within ventral midbrain dopaminergic neurons is one of the cardinal features of Parkinson’s disease. We employed molecular biology, electrophysiology, and live-cell imaging to investigate how excessive α-synuclein expression alters multiple characteristics of dopaminergic neuronal dynamics and dopamine transmission in cultured dopamine neurons conditionally expressing GCaMP6f. We found that overexpression of α-synuclein in mouse (male and female) dopaminergic neurons altered neuronal firing properties, calcium dynamics, dopamine release, protein expression, and morphology. Moreover, prolonged exposure to the D2 receptor agonist, quinpirole, rescues many of the alterations induced by α-synuclein overexpression. These studies demonstrate that α-synuclein dysregulation of neuronal activity contributes to the vulnerability of dopaminergic neurons and that modulation of D2 receptor activity can ameliorate the pathophysiology. These findings provide mechanistic insights into the insidious changes in dopaminergic neuronal activity and neuronal loss that characterize Parkinson’s disease progression with significant therapeutic implications.

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Dopamine D2 Long Receptors Are Critical for Caveolae-Mediated α-Synuclein Uptake in Cultured Dopaminergic Neurons

Biomedicines ◽

10.3390/biomedicines9010049 ◽

2021 ◽

Vol 9 (1) ◽

pp. 49

Author(s):

Ichiro Kawahata ◽

Tomoki Sekimori ◽

Haoyang Wang ◽

Yanyan Wang ◽

Toshikuni Sasaoka ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Neurons ◽

Dopamine D2 Receptor ◽

D2 Receptor ◽

Dopamine Neurons ◽

Fatty Acid Binding ◽

Caveolin 1 ◽

Dopamine D2 ◽

C Terminus

α-synuclein accumulation into dopaminergic neurons is a pathological hallmark of Parkinson’s disease. We previously demonstrated that fatty acid-binding protein 3 (FABP3) is critical for α-synuclein uptake and propagation to accumulate in dopaminergic neurons. FABP3 is abundant in dopaminergic neurons and interacts with dopamine D2 receptors, specifically the long type (D2L). Here, we investigated the importance of dopamine D2L receptors in the uptake of α-synuclein monomers and their fibrils. We employed mesencephalic neurons derived from dopamine D2L−/−, dopamine D2 receptor null (D2 null), FABP3−/−, and wild type C57BL6 mice, and analyzed the uptake ability of fluorescence-conjugated α-synuclein monomers and fibrils. We found that D2L receptors are co-localized with FABP3. Immunocytochemistry revealed that TH+ D2L−/− or D2 null neurons do not take up α-synuclein monomers. The deletion of α-synuclein C-terminus completely abolished the uptake to dopamine neurons. Likewise, dynasore, a dynamin inhibitor, and caveolin-1 knockdown also abolished the uptake. D2L and FABP3 were also critical for α-synuclein fibrils uptake. D2L and accumulated α-synuclein fibrils were well co-localized. These data indicate that dopamine D2L with a caveola structure coupled with FABP3 is critical for α-synuclein uptake by dopaminergic neurons, suggesting a novel pathogenic mechanism of synucleinopathies, including Parkinson’s disease.

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Dopamine D2 receptor activation potently inhibits striatal glutamatergic transmission in a G2019S LRRK2 genetic model of Parkinson's disease

Neurobiology of Disease ◽

10.1016/j.nbd.2018.06.008 ◽

2018 ◽

Vol 118 ◽

pp. 1-8 ◽

Cited By ~ 11

Author(s):

Alessandro Tozzi ◽

Valentina Durante ◽

Guendalina Bastioli ◽

Petra Mazzocchetti ◽

Salvatore Novello ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Genetic Model ◽

Dopamine D2 Receptor ◽

D2 Receptor ◽

Receptor Activation ◽

Glutamatergic Transmission ◽

Dopamine D2

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Dl-3-n-Butylphthalide Alleviates Behavioral and Cognitive Symptoms Via Modulating Mitochondrial Dynamics in the A53T-α-Synuclein Mouse Model of Parkinson’s Disease

Frontiers in Neuroscience ◽

10.3389/fnins.2021.647266 ◽

2021 ◽

Vol 15 ◽

Author(s):

Huiying Li ◽

Hongquan Wang ◽

Ling Zhang ◽

Manshi Wang ◽

Yanfeng Li

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Mouse Model ◽

Transgenic Mice ◽

Dopaminergic Neurons ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Control Group ◽

Mitochondrial Morphology ◽

Cognitive Symptoms

BackgroundAggregation and neurotoxicity of the presynaptic protein α-synuclein and the progressive loss of nigral dopaminergic neurons are believed to be the key hallmarks of Parkinson’s disease (PD). A53T mutant α-synuclein causes early onset PD and more severe manifestations. A growing body of evidence shows that misfolding or deposition of α-synuclein is linked to the maintenance of mitochondrial dynamics, which has been proven to play an important role in the pathogenesis of PD. It has been observed that Dl-3-n-butylphthalide (NBP) may be safe and effective in improving the non-tremor-dominant PD. However, the potential mechanism remains unclear. This study aimed to investigate whether NBP could decrease the loss of dopaminergic neurons and α-synuclein deposition and explore its possible neuroprotective mechanisms.MethodsA total of 20 twelve-month-old human A53T α-synuclein transgenic mice and 10 matched adult C57BL/6 mice were included in the study; 10 adult C57BL/6 mice were selected as the control group and administered with saline (0.2 ml daily for 14 days); 20 human A53T α-synuclein transgenic mice were randomly divided into A53T group (treated in the same manner as in the control group) and A53T + NBP group (treated with NBP 0.2 ml daily for 14 days). Several markers of mitochondrial fission and fusion and mitophagy were determined, and the behavioral, olfactory, and cognitive symptoms were assessed as well.ResultsIn the present study, it was observed that the A53T-α-synuclein PD mice exhibited anxiety-like behavioral disturbance, impairment of coordination ability, memory deficits, and olfactory dysfunction, loss of dopaminergic neurons, and α-synuclein accumulation. Meanwhile, the mitofusin 1 expression was significantly decreased, and the mitochondrial number and dynamin-related protein 1, Parkin, and LC3 levels were increased. The detected levels of all markers were reversed by NBP treatment, and the mitochondrial morphology was partially recovered.ConclusionIn the present study, a valuable neuropharmacological role of NBP has been established in the A53T-α-synuclein PD mouse model. Possible neuroprotective mechanisms might be that NBP is involved in the maintenance of mitochondrial dynamics including mitochondrial fission and fusion and clearance of damaged mitochondria. It is essential to perform further experiments to shed light on the precise mechanisms of NBP on mitochondrial homeostasis.

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Deconstructing the molecular genetics behind the PINK1/Parkin axis in Parkinson’s disease using Drosophila melanogaster as a model organism

Egyptian Journal of Medical Human Genetics ◽

10.1186/s43042-021-00208-2 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Suchita Ganesan ◽

Venkatachalam Deepa Parvathi

Keyword(s):

Oxidative Stress ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Neurons ◽

Neurodegenerative Disorder ◽

Ectopic Expression ◽

Model Organism ◽

E3 Ligase ◽

Mitochondrial Morphology ◽

Main Body

Abstract Background Parkinson’s disease (PD) is a multifactorial neurodegenerative disorder marked by the death of nigrostriatal dopaminergic neurons in response to the compounding effects of oxidative stress, mitochondrial dysfunction and protein aggregation. Transgenic Drosophila models have been used extensively to decipher the underlying genetic interactions that exacerbate neural health in PD. Autosomal recessive forms of the disease have been linked to mutations in the serine/threonine kinase PINK1(PTEN-Induced Putative Kinase 1) and E3 ligase Parkin, which function in an axis that is conserved in flies. This review aims to probe the current understanding of PD pathogenesis via the PINK1/Parkin axis while underscoring the importance of several molecular and pharmacologic rescues brought to light through studies in Drosophila. Main body Mutations in PINK1 and Parkin have been shown to affect the axonal transport of mitochondria within dopaminergic neurons and perturb the balance between mitochondrial fusion/fission resulting in abnormal mitochondrial morphology. As per studies in flies, ectopic expression of Fwd kinase and Atg-1 to promote fission and mitophagy while suppressing fusion via MUL1 E3 ligase may aid to halt mitochondrial aggregation and prolong the survival of dopaminergic neurons. Furthermore, upregulation of Hsp70/Hsp90 chaperone systems (Trap1, CHIP) to target misfolded mitochondrial respiratory complexes may help to preserve their bioenergetic capacity. Accumulation of reactive oxygen species as a consequence of respiratory complex dysfunction or antioxidant enzyme deficiency further escalates neural death by inducing apoptosis, lipid peroxidation and DNA damage. Fly studies have reported the induction of canonical Wnt signalling to enhance the activity of transcriptional co-activators (PGC1α, FOXO) which induce the expression of antioxidant enzymes. Enhancing the clearance of free radicals via uncoupling proteins (UCP4) has also been reported to ameliorate oxidative stress-induced cell death in PINK1/Parkin mutants. Conclusion While these novel mechanisms require validation through mammalian studies, they offer several explanations for the factors propagating dopaminergic death as well as promising insights into the therapeutic importance of transgenic fly models in PD.

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Induced Pluripotent Stem Cell-Derived Dopaminergic Neurons from Familial Parkinson’s Disease Patients Display α-Synuclein Pathology and Abnormal Mitochondrial Morphology

Cells ◽

10.3390/cells10092402 ◽

2021 ◽

Vol 10 (9) ◽

pp. 2402

Author(s):

Xiaojun Diao ◽

Fei Wang ◽

Andrea Becerra-Calixto ◽

Claudio Soto ◽

Abhisek Mukherjee

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Neurons ◽

Healthy Donor ◽

Lewy Bodies ◽

Neuronal Culture ◽

Mitochondrial Morphology ◽

Neuronal Cultures ◽

Mitochondrial Abnormalities ◽

Induced Pluripotent

Accumulation of α-synuclein (α-syn) into Lewy bodies (LBs) and mitochondrial abnormalities are the two cardinal pathobiological features of Parkinson’s disease (PD), which are associated with the loss of dopaminergic neurons. Although α-syn accumulates in many different cellular and mouse models, these models generally lack LB features. Here, we generated midbrain dopaminergic (mDA) neuronal cultures from induced pluripotent stem cells (iPSCs) derived from familial PD (fPD) patients and healthy controls. We show that mDA neuronal cultures from fPD patients with A53T mutation and α-syn gene (SNCA) triplication display pathological α-syn deposits, which spatially and morphologically resemble LBs. Importantly, we did not find any apparent accumulation of pathological α-syn in mDA neuronal culture derived from a healthy donor. Furthermore, we show that there are morphological abnormalities in the mitochondrial network in mDA neuronal cultures from fPD patients. Consequently, these cells were more susceptible to mitochondrial damage compared with healthy donor-derived mDA neuronal cultures. Our results indicate that the iPSC-derived mDA neuronal culture platform can be used to investigate the spatiotemporal appearance of LBs, as well as their composition, architecture, and relationship with mitochondrial abnormalities.

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Delta Oscillations Are a Robust Biomarker of Dopamine Depletion Severity and Motor Dysfunction in Awake Mice

10.1101/2020.02.09.941161 ◽

2020 ◽

Cited By ~ 1

Author(s):

Timothy C. Whalen ◽

Amanda M. Willard ◽

Jonathan E. Rubin ◽

Aryn H. Gittis

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

D2 Receptor ◽

Receptor Activation ◽

Motor Dysfunction ◽

Dopamine Depletion ◽

Novel Approach ◽

Strong Indicator ◽

Insight Into ◽

Delta Oscillations

AbstractDelta oscillations (0.5–4 Hz) are a robust but often overlooked feature of basal ganglia pathophysiology in Parkinson’s disease and their relationship to parkinsonian akinesia has not been investigated. Here, we establish a novel approach to detect spike oscillations embedded in noise to provide the first study of delta oscillations in awake, dopamine depleted mice. We find that approximately half of neurons in the substantia nigra reticulata exhibit delta oscillations in dopamine depletion and that these oscillations are a strong indicator of dopamine loss and akinesia, outperforming measures such as changes in firing rate, irregularity, bursting and synchrony. We further establish that these oscillations are caused by the loss of D2 receptor activation and do not require motor cortex, contrary to previous findings in anesthetized animals. These results give insight into how dopamine loss leads to dysfunction and suggest a reappraisal of delta oscillations as a biomarker in Parkinson’s disease.

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Novel insights in the pathophysiology of α-synuclein dysregulation on D2 receptor activity contributing to the vulnerability of dopamine neurons

10.1101/2021.03.30.437775 ◽

2021 ◽

Author(s):

Abeer Dagra ◽

Douglas R Miller ◽

Fatemeh Shaerzadeh ◽

Min Lin ◽

Adithya Gopinath ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Neurons ◽

D2 Receptor ◽

Dopamine Neurons ◽

Loss Of Function ◽

Neuronal Dynamics ◽

Therapeutic Implications ◽

Midbrain Dopaminergic Neurons ◽

Multiple Characteristics

Pathophysiological damages and loss of function of dopamine neurons precedes their demise and contributes to the early phases of Parkinson's disease. The presence of aberrant intercellular pathological inclusions of the protein α-synuclein within ventral midbrain dopaminergic neurons is one of the cardinal features of Parkinson's disease. We employed multiple complementary approaches in molecular biology, electrophysiology, and live-cell imaging to investigate how excessive α-synuclein levels alters multiple characteristics of dopaminergic neuronal dynamics and dopamine transmission prior to neuronal demise. These studies demonstrate that α-synuclein dysregulation of D2 receptor autoinhibition contributes to the vulnerability of dopaminergic neurons, and that modulation thereof can ameliorate the resulting pathophysiology. These novel findings provide mechanistic insights in the insidious loss of dopaminergic function and neurons that characterize Parkinson's disease progression with significant therapeutic implications.

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Toxicity of Necrostatin-1 in Parkinson’s Disease Models

Antioxidants ◽

10.3390/antiox9060524 ◽

2020 ◽

Vol 9 (6) ◽

pp. 524

Author(s):

Eva Alegre-Cortés ◽

Alicia Muriel-González ◽

Saray Canales-Cortés ◽

Elisabet Uribe-Carretero ◽

Guadalupe Martínez-Chacón ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Cell Death ◽

Dopaminergic Neurons ◽

Neurodegenerative Disorder ◽

Neuronal Loss ◽

Environmental Toxins ◽

Substantia Nigra Pars Compacta ◽

Mitochondrial Morphology ◽

Primary Fibroblasts

Parkinson’s disease (PD) is a neurodegenerative disorder that is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. This neuronal loss, inherent to age, is related to exposure to environmental toxins and/or a genetic predisposition. PD-induced cell death has been studied thoroughly, but its characterization remains elusive. To date, several types of cell death, including apoptosis, autophagy-induced cell death, and necrosis, have been implicated in PD progression. In this study, we evaluated necroptosis, which is a programmed type of necrosis, in primary fibroblasts from PD patients with and without the G2019S leucine-rich repeat kinase 2 (LRRK2) mutation and in rotenone-treated cells (SH-SY5Y and fibroblasts). The results showed that programmed necrosis was not activated in the cells of PD patients, but it was activated in cells exposed to rotenone. Necrostatin-1 (Nec-1), an inhibitor of the necroptosis pathway, prevented rotenone-induced necroptosis in PD models. However, Nec-1 affected mitochondrial morphology and failed to protect mitochondria against rotenone toxicity. Therefore, despite the inhibition of rotenone-mediated necroptosis, PD models were susceptible to the effects of both Nec-1 and rotenone.

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