scholarly journals Trafficking of the glutamate transporter is impaired in LRRK2-related Parkinson's disease

2021 ◽  
Author(s):  
Ludovica Iovino ◽  
Veronica Giusti ◽  
Francesca Pischedda ◽  
Elena Giusto ◽  
Nicoletta Plotegher ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Plasma Membrane ◽  
Excitatory Amino Acid ◽  
Late Onset ◽  
Glutamate Transporter ◽  
Xenopus Laevis Oocytes ◽  
Excitatory Amino Acid Transporter ◽  
Protein Levels ◽  
Lrrk2 G2019s

The Excitatory Amino Acid Transporter 2 (EAAT2) accounts for 80% of brain glutamate clearance and is mainly expressed in astrocytic perisynaptic processes. EAAT2 function is finely regulated by endocytic events, recycling to the plasma membrane and degradation. Noteworthy, deficits in EAAT2 have been associated with neuronal excitotoxicity and neurodegeneration. In this study, we show that EAAT2 trafficking is impaired by the leucine-rich repeat kinase 2 (LRRK2) pathogenic variant G2019S, a common cause of late-onset familial Parkinson's disease (PD). In LRRK2 G2019S human brains and experimental animal models, EAAT2 protein levels are significantly decreased, which is associated with elevated gliosis. The decreased expression of the transporter correlates with its reduced functionality in mouse LRRK2 G2019S purified astrocytic terminals and in Xenopus laevis oocytes expressing human LRRK2 G2019S. In Lrrk2 G2019S knockin mouse brain, the correct surface localization of the endogenous transporter is impaired, resulting in its interaction with a plethora of endo-vesicular proteins. Mechanistically, we report that pathogenic LRRK2 kinase activity delays the recycling of the transporter to the plasma membrane, causing its intracellular relocalization and degradation. Taken together, our results demonstrate that pathogenic LRRK2 interferes with the physiology of EAAT2, pointing to extracellular glutamate overload as a possible contributor to neurodegeneration in PD.

scholarly journals MicroRNA-128 Protects Dopamine Neurons from Apoptosis and Upregulates the Expression of Excitatory Amino Acid Transporter 4 in Parkinson’s Disease by Binding to AXIN1

2018 ◽  
Vol 51 (5) ◽  
pp. 2275-2289 ◽  
Author(s):  
Lei Zhou ◽  
Li Yang ◽  
Yu-jin Li ◽  
Rong Mei ◽  
Hua-lin Yu ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amino Acid ◽  
Excitatory Amino Acid ◽  
Amino Acid Transporter ◽  
Excitatory Amino Acid Transporter ◽  
Protein Levels ◽  
Positive Expression ◽  
Expression Rate ◽  
Acid Transporter

Background/Aims: Parkinson’s disease (PD) is a frequently occurring condition that resulted from the loss of midbrain neurons, which synthesize the neurotransmitter dopamine. In this study, we established mouse models of PD to investigate the expression of microRNA-128 (miR-128) and mechanism through which it affects apoptosis of dopamine (DA) neurons and the expression of excitatory amino acid transporter 4 (EAAT4) via binding to axis inhibition protein 1 (AXIN1). Methods: Gene expression microarray analysis was performed to screen differentially expressed miRNAs that are associated with PD. The targeting relationship between miR-128 and AXIN1 was verified via a bioinformatics prediction and dual-luciferase reporter gene assay. After separation, DA neurons were subjected to a series of inhibitors, activators and shRNAs to validate the mechanisms of miR-128 in controlling of AXIN1 in PD. Positive protein expression of AXIN1 and EAAT4 in DA neurons was determined using immunocytochemistry. miR-128 expression and the mRNA and protein levels of AXIN1 and EAAT4 were evaluated via RT-qPCR and Western blot analysis, respectively. DA neuron apoptosis was evaluated using TUNEL staining. Results: We identified AXIN1 as an upregulated gene in PD based on the microarray data of GSE7621. AXIN1 was targeted and negatively mediated by miR-128. In the DA neurons, upregulated miR-128 expression or sh-AXIN1 increased the positive expression rate of EAAT4 together with mRNA and protein levels, but decreased the mRNA and protein levels of AXIN1, apoptosis rate along with the positive expression rate of AXIN1; however, the opposite trend was found in response to transfection with miR-128 inhibitors. Conclusion: Evidence from experimental models revealed that miR-128 might reduce apoptosis of DA neurons while increasing the expression of EAAT4 which might be related to the downregulation of AXIN1. Thus, miR-128 may serve as a potential target for the treatment of PD.

scholarly journals A Novel LRRK2 Variant p.G2294R in the WD40 Domain Identified in Familial Parkinson’s Disease Affects LRRK2 Protein Levels

2021 ◽  
Vol 22 (7) ◽  
pp. 3708
Author(s):  
Jun Ogata ◽  
Kentaro Hirao ◽  
Kenya Nishioka ◽  
Arisa Hayashida ◽  
Yuanzhe Li ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Peripheral Blood ◽  
Kinase Activity ◽  
Late Onset ◽  
Causative Gene ◽  
Protein Levels ◽  
Wd40 Domain ◽  
Lrrk2 Protein ◽  
Familial Parkinson’S Disease

Leucine-rich repeat kinase 2 (LRRK2) is a major causative gene of late-onset familial Parkinson’s disease (PD). The suppression of kinase activity is believed to confer neuroprotection, as most pathogenic variants of LRRK2 associated with PD exhibit increased kinase activity. We herein report a novel LRRK2 variant—p.G2294R—located in the WD40 domain, detected through targeted gene-panel screening in a patient with familial PD. The proband showed late-onset Parkinsonism with dysautonomia and a good response to levodopa, without cognitive decline or psychosis. Cultured cell experiments revealed that p.G2294R is highly destabilized at the protein level. The LRRK2 p.G2294R protein expression was upregulated in the patient’s peripheral blood lymphocytes. However, macrophages differentiated from the same peripheral blood showed decreased LRRK2 protein levels. Moreover, our experiment indicated reduced phagocytic activity in the pathogenic yeasts and α-synuclein fibrils. This PD case presents an example wherein the decrease in LRRK2 activity did not act in a neuroprotective manner. Further investigations are needed in order to elucidate the relationship between LRRK2 expression in the central nervous system and the pathogenesis caused by altered LRRK2 activity.

LRRK2 G2019S is a common mutation in Spanish patients with late-onset Parkinson's disease

2006 ◽  
Vol 395 (3) ◽  
pp. 224-226 ◽  
Author(s):  
Jon Infante ◽  
Eloy Rodríguez ◽  
Onofre Combarros ◽  
Ignacio Mateo ◽  
Ana Fontalba ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Late Onset ◽  
Common Mutation ◽  
Lrrk2 G2019s

scholarly journals Expression of Glutamate Transporters in Mouse Liver, Kidney, and Intestine

2018 ◽  
Vol 66 (3) ◽  
pp. 189-202 ◽  
Author(s):  
Qiu Xiang Hu ◽  
Sigrid Ottestad-Hansen ◽  
Silvia Holmseth ◽  
Bjørnar Hassel ◽  
Niels Christian Danbolt ◽  
...  
Keyword(s):  
Mouse Liver ◽  
Plasma Membranes ◽  
Excitatory Amino Acid ◽  
Splice Variants ◽  
Glutamate Transporter ◽  
Quantitative Information ◽  
Current View ◽  
Excitatory Amino Acid Transporter ◽  
Distal Small Intestine ◽  
Protein Levels

Glutamate transport activities have been identified not only in the brain, but also in the liver, kidney, and intestine. Although glutamate transporter distributions in the central nervous system are fairly well known, there are still uncertainties with respect to the distribution of these transporters in peripheral organs. Quantitative information is mostly lacking, and few of the studies have included genetically modified animals as specificity controls. The present study provides validated qualitative and semi-quantitative data on the excitatory amino acid transporter (EAAT)1–3 subtypes in the mouse liver, kidney, and intestine. In agreement with the current view, we found high EAAT3 protein levels in the brush borders of both the distal small intestine and the renal proximal tubules. Neither EAAT1 nor EAAT2 was detected at significant levels in murine kidney or intestine. In contrast, the liver only expressed EAAT2 (but 2 C-terminal splice variants). EAAT2 was detected in the plasma membranes of perivenous hepatocytes. These cells also expressed glutamine synthetase. Conditional deletion of hepatic EAAT2 did neither lead to overt neurological disturbances nor development of fatty liver.

scholarly journals Neuronal hyperactivity in a LRRK2-G2019S cellular model of Parkinson's Disease

2021 ◽  
Author(s):  
Edinson Lucumi Moreno ◽  
Siham Hachi ◽  
Sarah L Nickels ◽  
Kalid IW Kane ◽  
Masha Moein ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neuronal Activity ◽  
Late Onset ◽  
Induced Pluripotent Stem Cell ◽  
Calcium Transient ◽  
Lrrk2 Gene ◽  
Lrrk2 G2019s ◽  
Induced Pluripotent

Monogenic Parkinson's Disease can be caused by a mutation in the leucine-rich repeat kinase 2 (LRRK2) gene, causing a late-onset autosomal dominant inherited form of Parkinson's Disease. The function of the LRRK2 gene is incompletely understood, but several in vitro studies have reported that LRRK2-G2019S mutations affect neurite branching, calcium homeostasis and mitochondrial function, but thus far, there have been no reports of effects on electrophysiological activity. We assessed the neuronal activity of induced pluripotent stem cell derived neurons from Parkinson's Disease patients with LRRK2-G2019S mutations and isogenic controls. Neuronal activity of spontaneously firing neuronal populations was recorded with a fluorescent calcium-sensitive dye (Fluo-4) and analysed with a novel image analysis pipeline that combined semi-automated neuronal segmentation and quantification of calcium transient properties. Compared with controls, LRRK2-G2019S mutants have shortened inter-spike intervals and an increased rate of spontaneous calcium transient induction.

scholarly journals Effects of tranexamic acid on the activity of glutamate transporter EAAT3

2020 ◽  
Vol 15 (3) ◽  
pp. 291-296
Author(s):  
Hyun-Jung Shin ◽  
Soo-Young Lee ◽  
Hyo-Seok Na ◽  
Bon-Wook Koo ◽  
Jung-Hee Ryu ◽  
...  
Keyword(s):  
Tranexamic Acid ◽  
Excitatory Amino Acid ◽  
Glutamate Transporter ◽  
Control Group ◽  
High Dose ◽  
Xenopus Laevis Oocytes ◽  
Excitatory Amino Acid Transporter ◽  
Electrode Voltage ◽  
Voltage Clamping ◽  
Type 3

Background: Tranexamic acid (TXA) is the most widely used hemostatic agent in surgical patients. However, when used in a high dose, it could cause a seizure in the postoperative period. The exact effector mechanism behind the seizure triggering remains unknown. Therefore, the authors investigated the effects of TXA on the activity of glutamate transporter type 3 (excitatory amino acid transporter 3; EAAT3), which is the main neuronal glutamate transporter type. Methods: EAAT3 was expressed in Xenopus laevis oocytes through mRNA injection. Oocytes were incubated with diluted tranexamic acid for 72 h. Two-electrode voltage clamping was used to measure membrane currents before, during, and after applying 30 M L-glutamate. Responses were quantified by integrating the current traces and reported in microcoulombs (C). Results were presented as mean  SEM.Results: TXA (30 to 1,000 M) significantly decreased EAAT3 activity. Our kinetic study showed that Vmax was significantly decreased in the TXA group compared with the control group (1.1  0.1 vs. 1.4  0.1 C, n = 18–23, P = 0.043), but the Km did not significantly change (12.7  3.9 M for TXA vs. 12.8  3.8 for control, n = 18–23, P = 0.986).Conclusions: Our results suggest that TXA attenuates EAAT3 activity, which may explain its proconvulsant effect.

scholarly journals Glutamic Acid Transporters: Targets for Neuroprotective Therapies in Parkinson’s Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Xiang Li ◽  
Wenjun Wang ◽  
Jianghong Yan ◽  
Fancai Zeng
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Glutamic Acid ◽  
Drug Targets ◽  
Excitatory Amino Acid ◽  
Glutamate Transporter ◽  
Glutamate Transporters ◽  
Symptomatic Treatment ◽  
Amino Acid Transporters ◽  
Functional Roles

Parkinson’s disease (PD) is a common neurodegenerative disease in middle-aged and elderly individuals. At present, no effective drug has been developed to treat PD. Although a variety of drugs exist for the symptomatic treatment of PD, they all have strong side effects. Most studies on PD mainly focus on dopaminergic neurons. This review highlights the function of glutamic acid transporters (GLTs), including excitatory amino acid transporters (EAATs) and vesicular glutamate transporters (VGLUTs), during the development of PD. In addition, using bioinformatics, we compared the expression of different types of glutamate transporter genes in the cingulate gyrus of PD patients and healthy controls. More importantly, we suggest that the functional roles of glutamate transporters may prove beneficial in the treatment of PD. In summary, VGLUTs and EAATs may be potential targets in the treatment of PD. VGLUTs and EAATs can be used as clinical drug targets to achieve better efficacy. Through this review article, we hope to enable future researchers to improve the condition of PD patients.

scholarly journals (D620N) VPS35 causes the impairment of Wnt/β-catenin signaling cascade and mitochondrial dysfunction in a PARK17 knockin mouse model

2020 ◽  
Vol 11 (11) ◽  
Author(s):  
Ching-Chi Chiu ◽  
Yi-Hsin Weng ◽  
Ying-Zu Huang ◽  
Rou-Shayn Chen ◽  
Yu-Chuan Liu ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Autosomal Dominant ◽  
Late Onset ◽  
Substantia Nigra Pars Compacta ◽  
Protein Levels ◽  
Abnormal Morphology ◽  
Vacuolar Protein ◽  
Knockin Mouse ◽  
Active Caspase

AbstractPatients with familial type 17 of Parkinson’s disease (PARK17) manifest autosomal dominant pattern and late-onset parkinsonian syndromes. Heterozygous (D620N) mutation of vacuolar protein sorting 35 (VPS35) is genetic cause of PARK17. We prepared heterozygous VPS35D620N/+ knockin mouse, which is an ideal animal model of (D620N) VPS35-induced autosomal dominant PARK17. Late-onset loss of substantia nigra pars compacta (SNpc) dopaminergic (DAergic) neurons and motor deficits of Parkinson’s disease were found in 16-month-old VPS35D620N/+ mice. Normal function of VPS35-containing retromer is needed for activity of Wnt/β-catenin cascade, which participates in protection and survival of SNpc DAergic neurons. It was hypothesized that (D620N) VPS35 mutation causes the malfunction of VPS35 and resulting impaired activity of Wnt/β-catenin pathway. Protein levels of Wnt1 and nuclear β-catenin were reduced in SN of 16-month-old VPS35D620N/+ knockin mice. Downregulated protein expression of survivin, which is a target gene of nuclear β-catenin, and upregulated protein levels of active caspase-8 and active caspase-9 were observed in SN of VPS35D620N/+ mice at age of 16 months. VPS35 is involved in controlling morphology and function of mitochondria. Impaired function of VPS35 caused by (D620N) mutation could lead to abnormal morphology and malfunction of mitochondria. A significant decrease in mitochondrial size and resulting mitochondrial fragmentation was found in tyrosine hydroxylase-positive and neuromelanin-positive SNpc DAergic neurons of 16-month-old VPS35D620N/+ mice. Mitochondrial complex I activity or complex IV activity was reduced in SN of 16-month-old VPS35D620N/+ mice. Increased level of mitochondrial ROS and oxidative stress were found in SN of 16-month-old VPS35D620N/+ mice. Levels of cytosolic cytochrome c and active caspase-3 were increased in SN of VPS35D620N/+ mice aged 16 months. Our results suggest that PARK17 mutant (D620N) VPS35 impairs activity of Wnt/β-catenin signaling pathway and causes abnormal morphology and dysfunction of mitochondria, which could lead to neurodegeneration of SNpc DAergic cells.

scholarly journals Multiple Pathways of LRRK2-G2019S/Rab10 Interaction in Dopaminergic Neurons

2021 ◽  
pp. 1-16
Author(s):  
Alison Fellgett ◽  
C. Adam Middleton ◽  
Jack Munns ◽  
Chris Ugbode ◽  
David Jaciuch ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Dopaminergic Neurons ◽  
Genetic Interaction ◽  
In Vitro Assays ◽  
Rab Proteins ◽  
Circadian Activity ◽  
Loss Of Function ◽  
Lrrk2 G2019s

Background: Inherited mutations in the LRRK2 protein are the common causes of Parkinson’s disease, but the mechanisms by which increased kinase activity of mutant LRRK2 leads to pathological events remain to be determined. In vitro assays (heterologous cell culture, phospho-protein mass spectrometry) suggest that several Rab proteins might be directly phosphorylated by LRRK2-G2019S. An in vivo screen of Rab expression in dopaminergic neurons in young adult Drosophila demonstrated a strong genetic interaction between LRRK2-G2019S and Rab10. Objective: To determine if Rab10 is necessary for LRRK2-induced pathophysiological responses in the neurons that control movement, vision, circadian activity, and memory. These four systems were chosen because they are modulated by dopaminergic neurons in both humans and flies. Methods: LRRK2-G2019S was expressed in Drosophila dopaminergic neurons and the effects of Rab10 depletion on Proboscis Extension, retinal neurophysiology, circadian activity pattern (‘sleep’), and courtship memory determined in aged flies. Results: Rab10 loss-of-function rescued LRRK2-G2019S induced bradykinesia and retinal signaling deficits. Rab10 knock-down, however, did not rescue the marked sleep phenotype which results from dopaminergic LRRK2-G2019S. Courtship memory is not affected by LRRK2, but is markedly improved by Rab10 depletion. Anatomically, both LRRK2-G2019S and Rab10 are seen in the cytoplasm and at the synaptic endings of dopaminergic neurons. Conclusion: We conclude that, in Drosophila dopaminergic neurons, Rab10 is involved in some, but not all, LRRK2-induced behavioral deficits. Therefore, variations in Rab expression may contribute to susceptibility of different dopaminergic nuclei to neurodegeneration seen in people with Parkinson’s disease.

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