scholarly journals Reduced astrocytic reactivity in human brains and midbrain organoids with PRKN mutations

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Masayoshi Kano ◽  
Masashi Takanashi ◽  
Genko Oyama ◽  
Asako Yoritaka ◽  
Taku Hatano ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Glial Fibrillary Acidic Protein ◽  
Dopaminergic Neurons ◽  
Cell Loss ◽  
Acidic Protein ◽  
Patient Specific ◽  
Dopaminergic Cell ◽  
Induced Pluripotent ◽  
Human Brains ◽  
Defective Clearance

AbstractParkin (encoded by PRKN) is a ubiquitin ligase that plays an important role in cellular mitochondrial quality control. Mutations in PRKN cause selective dopaminergic cell loss in the substantia nigra and are presumed to induce a decrease in mitochondrial function caused by the defective clearance of mitochondria. Several studies have demonstrated that parkin dysfunction causes mitochondrial injury and astrocytic dysfunction. Using immunohistochemical methods, we analyzed astrocytic changes in human brains from individuals with PRKN mutations. Few glial fibrillary acidic protein- and vimentin-positive astrocytes were observed in the substantia nigra in PRKN-mutated subjects compared with subjects with idiopathic Parkinson’s disease. We also differentiated patient-specific induced pluripotent stem cells into midbrain organoids and confirmed decreased numbers of glial fibrillary acidic protein-positive astrocytes in PRKN-mutated organoids compared with age- and sex-matched controls. Our study reveals PRKN-mutation-induced astrocytic alteration and suggests the possibility of an astrocyte-related non-autonomous cell death mechanism for dopaminergic neurons in brains of PRKN-mutated patients.

scholarly journals Association Between Decreased Srpk3 Expression And An Increase In Substantia Nigra Alpha-Synuclein Levels In An MPTP-Induced Parkinson’s Disease Mouse Model

2022 ◽  
Author(s):  
Min Hyung Seo ◽  
Sujung Yeo
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Substantia Nigra ◽  
Dopaminergic Neurons ◽  
Cell Loss ◽  
Alpha Synuclein ◽  
Mice Model ◽  
Dopaminergic Cell ◽  
The Brain

Abstract Parkinson’s disease (PD) is known as the second most common neurodegenerative disease, which is caused by destruction of dopaminergic neurons in the substantia nigra (SN) of the brain; however, the reason for the death of dopaminergic neurons remains unclear. An increase in α-synuclein (α-syn) is considered an important factor in the pathogenesis of PD. In the current study, we investigated the association between PD and serine/arginine-rich protein specific kinase 3 (Srpk3) in MPTP-induced parkinsonism mice model and in SH-SY5Y cells treated with MPP+. Srpk3 expression was significantly downregulated, while tyrosine hydroxylase (TH) decreased and α-synuclein (α-syn) increased after 4 weeks of MPTP intoxication treatment. Dopaminergic cell reduction and α-syn increase were demonstrated by inhibiting Srpk3 expression by siRNA in SH-SY5Y cells. Moreover, a decrease in Srpk3 expression upon siRNA treatment promoted dopaminergic cell reduction and α-syn increase in SH-SY5Y cells treated with MPP+. These results suggest that the decrease in Srpk3 expression due to Srpk3 siRNA caused both a decrease in TH and an increase in α-syn. This raises new possibilities for studying how Srpk3 controls dopaminergic cells and α-syn expression, which may be related to the pathogenesis of PD. Our results provide an avenue for understanding the role of Srpk3 during dopaminergic cell loss and α-syn increase in the SN. Furthermore, this study could support a therapeutic possibility for PD in that the maintenance of Srpk3 expression inhibited dopaminergic cell reduction.

Knockin mice with Leu9′Ser α4-nicotinic receptors: substantia nigra dopaminergic neurons are hypersensitive to agonist and lost postnatally

2004 ◽  
Vol 18 (3) ◽  
pp. 299-307 ◽  
Author(s):  
Sabine Orb ◽  
Johannes Wieacker ◽  
Cesar Labarca ◽  
Carlos Fonck ◽  
Henry A. Lester ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Dopaminergic Neurons ◽  
Nicotinic Receptors ◽  
Cell Loss ◽  
Neuron Death ◽  
Dopaminergic Cell ◽  
Excitatory Response ◽  
Increased Sensitivity ◽  
Novel Concept ◽  
Knockin Mouse

This study analyzes the electrophysiological cause and behavioral consequence of dopaminergic cell loss in a knockin mouse strain bearing hypersensitive nicotinic α4-receptor subunits (“L9′S mice”). Adult brains of L9′S mice show moderate loss of substantia nigra dopaminergic neurons and of striatal dopaminergic innervation. Amphetamine-stimulated locomotion is impaired, reflecting a reduction of dopamine stored in presynaptic vesicles. Recordings from dopaminergic neurons in L9′S mice show that 10 μM nicotine depolarizes cells and increases spiking rates in L9′S cells but hyperpolarizes and decreases spiking rates in wild-type (WT) cells. Thus dopaminergic neurons of L9′S mice have an excitatory response to nicotine which is qualitatively different from that of WT neurons. The cause of dopaminergic cell death is therefore probably an increased sensitivity to acetylcholine or choline of α4-containing nicotinic receptors. Hypersensitive excitatory stimulation during activation of α4-containing receptors provides the first evidence for cholinergic excitotoxicity as a cause of dopaminergic neuron death. This novel concept may be relevant to the pathophysiology of Parkinson disease.

scholarly journals α-Synuclein Expression Is Preserved in Substantia Nigra GABAergic Fibers of Young and Aged Neurotoxin-Treated Rhesus Monkeys

2019 ◽  
Vol 28 (4) ◽  
pp. 379-387
Author(s):  
Scott C. Vermilyea ◽  
Scott Guthrie ◽  
Iliana Hernandez ◽  
Viktorya Bondarenko ◽  
Marina E. Emborg
Keyword(s):  
Substantia Nigra ◽  
Optical Density ◽  
Dopaminergic Neurons ◽  
Rhesus Monkeys ◽  
Lewy Bodies ◽  
Cell Loss ◽  
Contralateral Side ◽  
Soluble Form ◽  
Mptp Administration ◽  
Presynaptic Protein

α-Synuclein (α-syn) is a small presynaptic protein distributed ubiquitously in the central and peripheral nervous system. In normal conditions, α-syn is found in soluble form, while in Parkinson’s disease (PD) it may phosphorylate, aggregate, and combine with other proteins to form Lewy bodies. The purpose of this study was to evaluate, in nonhuman primates, whether α-syn expression is affected by age and neurotoxin challenge. Young adult ( n = 5, 5–10 years old) and aged ( n = 4, 23–25 years old) rhesus monkeys received a single unilateral carotid artery injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Three months post-MPTP the animals were necropsied by transcardiac perfusion, and their brains extracted and processed with immunohistochemical methods. Quantification of tyrosine hydroxylase (TH)-positive substantia nigra (SN) neurons showed a significant 80–89% decrease in the side ipsilateral to MPTP administration in young and old animals. Optical density of TH- immunoreactivity (-ir) in the caudate and putamen presented a 60–70% loss compared with the contralateral side. α-Syn-ir was present in both ipsi- and contra- lateral MPTP-treated nigra, caudate, and putamen, mostly in fibers; its intracellular distribution was not affected by age. Comparison of α-syn-ir between MPTP-treated young and aged monkeys revealed significantly higher optical density for both the ipsi- and contralateral caudate and SN in the aged animals. TH and α-syn immunofluorescence confirmed the loss of nigral TH-ir dopaminergic neurons in the MPTP-treated side of intoxicated animals, but bilateral α-syn expression. Colabeling of GAD67 and α-syn immunofluorescence showed that α-syn expression was present mainly in GABAergic fibers. Our results demonstrate that, 3 months post unilateral intracarotid artery infusion of MPTP, α-syn expression in the SN is largely present in GABAergic fibers, regardless of age. Bilateral increase of α-syn expression in SN fibers of aged, compared with young rhesus monkeys, suggests that α-syn-ir may increase with age, but not after neurotoxin-induced dopaminergic nigral cell loss.

scholarly journals Pharmacological Transdifferentiation of Human Nasal Olfactory Stem Cells into Dopaminergic Neurons

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Audrey Chabrat ◽  
Emmanuelle Lacassagne ◽  
Rodolphe Billiras ◽  
Sophie Landron ◽  
Amélie Pontisso-Mahout ◽  
...  
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Neurodegenerative Diseases ◽  
Dopaminergic Neurons ◽  
Adult Stem Cells ◽  
Morphological Changes ◽  
Direct Conversion ◽  
Patient Specific ◽  
Induced Pluripotent

The discovery of novel drugs for neurodegenerative diseases has been a real challenge over the last decades. The development of patient- and/or disease-specific in vitro models represents a powerful strategy for the development and validation of lead candidates in preclinical settings. The implementation of a reliable platform modeling dopaminergic neurons will be an asset in the study of dopamine-associated pathologies such as Parkinson’s disease. Disease models based on cell reprogramming strategies, using either human-induced pluripotent stem cells or transcription factor-mediated transdifferentiation, are among the most investigated strategies. However, multipotent adult stem cells remain of high interest to devise direct conversion protocols and establish in vitro models that could bypass certain limitations associated with reprogramming strategies. Here, we report the development of a six-step chemically defined protocol that drives the transdifferentiation of human nasal olfactory stem cells into dopaminergic neurons. Morphological changes were progressively accompanied by modifications matching transcript and protein dopaminergic signatures such as LIM homeobox transcription factor 1 alpha (LMX1A), LMX1B, and tyrosine hydroxylase (TH) expression, within 42 days of differentiation. Phenotypic changes were confirmed by the production of dopamine from differentiated neurons. This new strategy paves the way to develop more disease-relevant models by establishing reprogramming-free patient-specific dopaminergic cell models for drug screening and/or target validation for neurodegenerative diseases.

scholarly journals The Use of Glial Fibrillary Acidic Protein in First-Tier Assessments of Neurotoxicity

1991 ◽  
Vol 10 (6) ◽  
pp. 719-726 ◽  
Author(s):  
James P. O'Callaghan
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Cell Loss ◽  
Acidic Protein ◽  
Intermediate Filament Protein ◽  
Pharmacological Agents ◽  
Cellular Targets ◽  
Dose Time ◽  
Enhanced Expression ◽  
Second Tier ◽  
Filament Protein

Diverse neurotoxic insults result in proliferation and hypertrophy of astrocytes, a subtype of central nervous system glia. The hallmark of this response, often termed “reactive gliosis,” is the enhanced expression of the major intermediate filament protein of astrocytes, glial fibrillary acidic protein (GFAP). These morphological observations suggest that GFAP may be a useful biochemical indicator of neurotoxicity. To investigate this possibility we have administered prototype neurotoxicants to experimental animals and then assessed the effects of these agents on the tissue content of GFAP, as determined by radioimmunoassay. We found that assays of GFAP reveal dose-, time-, and region-dependent patterns of neurotoxicity at toxicant dosages below those that cause light microscopic evidence of cell loss or damage. No false positives have been seen following exposure to a variety of pharmacological agents. By using regional assessments of GFAP in a first-tier evaluation, it should be possible to localize areas of damage. A second-tier evaluation, using assays of proteins or transmitters associated with cells in the affected region, may reveal the cellular targets of neurotoxicity. This two-tiered approach should serve as a foundation for guiding studies aimed at determining mechanisms of neurotoxicity.

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