Managing risky assets – mitophagy in vivo

ABSTRACT Mitochondria, which resemble their α-proteobacteria ancestors, are a major cellular asset, producing energy ‘on the cheap’ through oxidative phosphorylation. They are also a liability. Increased oxidative phosphorylation means increased oxidative stress, and damaged mitochondria incite inflammation through release of their bacteria-like macromolecules. Mitophagy (the selective macroautophagy of mitochondria) controls mitochondria quality and number to manage these risky assets. Parkin, BNIP3 and NIX were identified as being part of the first mitophagy pathways identified in mammals over a decade ago, with additional pathways, including that mediated by FUNDC1 reported more recently. Loss of Parkin or PINK1 function causes Parkinson's disease, highlighting the importance of mitophagy as a quality control mechanism in the brain. Additionally, mitophagy is induced in idiopathic Parkinson's disease and Alzheimer's disease, protects the heart and other organs against energy stress and lipotoxicity, regulates metabolism by controlling mitochondrial number in brown and beige fat, and clears mitochondria during terminal differentiation of glycolytic cells, such as red blood cells and neurons. Despite its importance in disease, mitophagy is likely dispensable under physiological conditions. This Review explores the in vivo roles of mitophagy in mammalian systems, focusing on the best studied examples – mitophagy in neurodegeneration, cardiomyopathy, metabolism, and red blood cell development – to draw out common themes.

Download Full-text

Microglial exosomes facilitate α-synuclein transmission in Parkinson’s disease

Brain ◽

10.1093/brain/awaa090 ◽

2020 ◽

Vol 143 (5) ◽

pp. 1476-1497 ◽

Cited By ~ 12

Author(s):

Min Guo ◽

Jian Wang ◽

Yanxin Zhao ◽

Yiwei Feng ◽

Sida Han ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Protein Aggregation ◽

Brain Regions ◽

Dependent Manner ◽

Nigrostriatal Pathway ◽

Stereotaxic Injection ◽

Promising Therapeutic Target ◽

The Brain

Abstract Accumulation of neuronal α-synuclein is a prominent feature in Parkinson’s disease. More recently, such abnormal protein aggregation has been reported to spread from cell to cell and exosomes are considered as important mediators. The focus of such research, however, has been primarily in neurons. Given the increasing recognition of the importance of non-cell autonomous-mediated neurotoxicity, it is critical to investigate the contribution of glia to α-synuclein aggregation and spread. Microglia are the primary phagocytes in the brain and have been well-documented as inducers of neuroinflammation. How and to what extent microglia and their exosomes impact α-synuclein pathology has not been well delineated. We report here that when treated with human α-synuclein preformed fibrils, exosomes containing α-synuclein released by microglia are fully capable of inducing protein aggregation in the recipient neurons. Additionally, when combined with microglial proinflammatory cytokines, these exosomes further increased protein aggregation in neurons. Inhibition of exosome synthesis in microglia reduced α-synuclein transmission. The in vivo significance of these exosomes was demonstrated by stereotaxic injection of exosomes isolated from α-synuclein preformed fibrils treated microglia into the mouse striatum. Phosphorylated α-synuclein was observed in multiple brain regions consistent with their neuronal connectivity. These animals also exhibited neurodegeneration in the nigrostriatal pathway in a time-dependent manner. Depleting microglia in vivo dramatically suppressed the transmission of α-synuclein after stereotaxic injection of preformed fibrils. Mechanistically, we report here that α-synuclein preformed fibrils impaired autophagy flux by upregulating PELI1, which in turn, resulted in degradation of LAMP2 in activated microglia. More importantly, by purifying microglia/macrophage derived exosomes in the CSF of Parkinson’s disease patients, we confirmed the presence of α-synuclein oligomer in CD11b+ exosomes, which were able to induce α-synuclein aggregation in neurons, further supporting the translational aspect of this study. Taken together, our study supports the view that microglial exosomes contribute to the progression of α-synuclein pathology and therefore, they may serve as a promising therapeutic target for Parkinson’s disease.

Download Full-text

AnIn VivoMicrodialysis Study of FLZ Penetration through the Blood-Brain Barrier in Normal and 6-Hydroxydopamine Induced Parkinson’s Disease Model Rats

BioMed Research International ◽

10.1155/2014/850493 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

Jinfeng Hou ◽

Qian Liu ◽

Yingfei Li ◽

Hua Sun ◽

Jinlan Zhang

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Disease Model ◽

Time Curve ◽

Liquid Chromatography Tandem Mass ◽

Bbb Permeability ◽

6 Hydroxydopamine ◽

The Brain ◽

Active Substances

FLZ (N-[2-(4-hydroxy-phenyl)-ethyl]-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) is a novel synthetic squamosamide derivative and a potential anti-Parkinson’s disease (PD) agent. The objective of the present study was to investigate the penetration of free FLZ across the BBB and the effects of P-gp inhibition on FLZ transport in normal and 6-hydroxydopamine (6-OHDA) induced PD model rats.In vivomicrodialysis was used to collect FLZ containing brain and blood dialysates following intravenous (i.v.) drug administration either with or without pretreatment with the specific P-gp inhibitor, zosuquidar trihydrochloride (zosuquidar·3HCl). A sensitive, rapid, and reliable ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was developed and validated to quantitate free FLZ levels in the dialysates. No significant differences were observed in the brain/blood FLZ area under the concentration-time curve (AUC) ratio between normal and PD model rats. However, pretreatment with zosuquidar·3HCl markedly increased the AUC ratio in both rat models. In addition, FLZ penetration was similar in zosuquidar·3HCl-pretreated normal and PD rats. These results suggest that P-gp inhibition increases BBB permeability to FLZ, thereby supporting the hypothesis that P-gp normally restricts FLZ transfer to the brain. These findings could provide reference data for future clinical trials and may aid investigation of the BBB permeability of other CNS-active substances.

Download Full-text

Protein Deimination Signatures in Plasma and Plasma-EVs and Protein Deimination in the Brain Vasculature in a Rat Model of Pre-Motor Parkinson’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms21082743 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2743 ◽

Cited By ~ 5

Author(s):

Marco Sancandi ◽

Pinar Uysal-Onganer ◽

Igor Kraev ◽

Audrey Mercer ◽

Sigrun Lange

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Rat Model ◽

Lupus Erythematosus ◽

Biomarker Discovery ◽

Alcoholic Fatty Liver ◽

Brain Vasculature ◽

Micro Rnas ◽

The Brain

The identification of biomarkers for early diagnosis of Parkinson’s disease (PD) is of pivotal importance for improving approaches for clinical intervention. The use of translatable animal models of pre-motor PD therefore offers optimal opportunities for novel biomarker discovery in vivo. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that contribute to protein misfolding through post-translational deimination of arginine to citrulline. Furthermore, PADs are an active regulator of extracellular vesicle (EV) release. Both protein deimination and extracellular vesicles (EVs) are gaining increased attention in relation to neurodegenerative diseases, including in PD, while roles in pre-motor PD have yet to be investigated. The current study aimed at identifying protein candidates of deimination in plasma and plasma-EVs in a rat model of pre-motor PD, to assess putative contributions of such post-translational changes in the early stages of disease. EV-cargo was further assessed for deiminated proteins as well as three key micro-RNAs known to contribute to inflammation and hypoxia (miR21, miR155, and miR210) and also associated with PD. Overall, there was a significant increase in circulating plasma EVs in the PD model compared with sham animals and inflammatory and hypoxia related microRNAs were significantly increased in plasma-EVs of the pre-motor PD model. A significantly higher number of protein candidates were deiminated in the pre-motor PD model plasma and plasma-EVs, compared with those in the sham animals. KEGG (Kyoto encyclopedia of genes and genomes) pathways identified for deiminated proteins in the pre-motor PD model were linked to “Alzheimer’s disease”, “PD”, “Huntington’s disease”, “prion diseases”, as well as for “oxidative phosphorylation”, “thermogenesis”, “metabolic pathways”, “Staphylococcus aureus infection”, gap junction, “platelet activation”, “apelin signalling”, “retrograde endocannabinoid signalling”, “systemic lupus erythematosus”, and “non-alcoholic fatty liver disease”. Furthermore, PD brains showed significantly increased staining for total deiminated proteins in the brain vasculature in cortex and hippocampus, as well as increased immunodetection of deiminated histone H3 in dentate gyrus and cortex. Our findings identify EVs and post-translational protein deimination as novel biomarkers in early pre-motor stages of PD.

Download Full-text

Cerebral Mitochondrial Metabolism in Early Parkinson's Disease

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2008.63 ◽

2008 ◽

Vol 28 (10) ◽

pp. 1754-1760 ◽

Cited By ~ 26

Author(s):

William J Powers ◽

Tom O Videen ◽

Joanne Markham ◽

Kevin J Black ◽

Nima Golchin ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Electron Transport ◽

Oxidative Phosphorylation ◽

Metabolic Rate ◽

Metabolic Demand ◽

Primary Analysis ◽

Cerebral Metabolic Rate ◽

Reduced Activity

Abnormal cerebral energy metabolism owing to dysfunction of mitochondrial electron transport has been implicated in the pathogenesis of Parkinson's disease (PD). However, in vivo data of mitochondrial dysfunction have been inconsistent. We directly investigated mitochondrial oxidative metabolism in vivo in 12 patients with early, never-medicated PD and 12 age-matched normal controls by combined measurements of the cerebral metabolic rate of oxygen (CMRO2) and the cerebral metabolic rate of glucose (CMRglc) with positron emission tomography. The primary analysis showed a statistically significant 24% increase in bihemispheric CMRO2 and no change in CMRO2/CMRglc. These findings are inconsistent with a defect in mitochondrial oxidative phosphorylation owing to reduced activity of the mitochondrial electron transport system (ETS). Because PD symptoms were already manifest, deficient energy production owing to a reduced activity of the mitochondrial ETS cannot be a primary mechanism of neuronal death in early PD. Alternatively, this general increase in CMRO2 could be due not to an increased metabolic demand but to an uncoupling of ATP production from oxidation in the terminal stage of oxidative phosphorylation. Whether this is the case in early PD and whether it is important in the pathogenesis of PD will require further study.

Download Full-text

Mutant LRRK2 mediates peripheral and central immune responses leading to neurodegeneration in vivo

Brain ◽

10.1093/brain/awy077 ◽

2018 ◽

Vol 141 (6) ◽

pp. 1753-1769 ◽

Cited By ~ 35

Author(s):

Elena Kozina ◽

Shankar Sadasivan ◽

Yun Jiao ◽

Yuchen Dou ◽

Zhijun Ma ◽

...

Keyword(s):

Parkinson’S Disease ◽

Immune Response ◽

Parkinson's Disease ◽

Late Onset ◽

Incomplete Penetrance ◽

Missense Mutations ◽

Wild Type ◽

Mutant Lrrk2 ◽

The Brain

Abstract Missense mutations in the leucine rich repeat kinase 2 (LRRK2) gene result in late-onset Parkinson’s disease. The incomplete penetrance of LRRK2 mutations in humans and LRRK2 murine models of Parkinson’s disease suggests that the disease may result from a complex interplay of genetic predispositions and persistent exogenous insults. Since neuroinflammation is commonly associated with the pathogenesis of Parkinson’s disease, we examine a potential role of mutant LRRK2 in regulation of the immune response and inflammatory signalling in vivo. Here, we show that mice overexpressing human pathogenic LRRK2 mutations, but not wild-type mice or mice overexpressing human wild-type LRRK2 exhibit long-term lipopolysaccharide-induced nigral neuronal loss. This neurodegeneration is accompanied by an exacerbated neuroinflammation in the brain. The increased immune response in the brain of mutant mice subsequently has an effect on neurons by inducing intraneuronal LRRK2 upregulation. However, the enhanced neuroinflammation is unlikely to be triggered by dysfunctional microglia or infiltrated T cells and/or monocytes, but by peripheral circulating inflammatory molecules. Analysis of cytokine kinetics and inflammatory pathways in the peripheral immune cells demonstrates that LRRK2 mutation alters type II interferon immune response, suggesting that this increased neuroinflammatory response may arise outside the central nervous system. Overall, this study suggests that peripheral immune signalling plays an unexpected—but important—role in the regulation of neurodegeneration in LRRK2-associated Parkinson’s disease, and provides new targets for interfering with the onset and progression of the disease.

Download Full-text

Novel Approaches Used to Examine and Control Neurogenesis in Parkinson′s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms22179608 ◽

2021 ◽

Vol 22 (17) ◽

pp. 9608

Author(s):

Alla B. Salmina ◽

Marina R. Kapkaeva ◽

Anna S. Vetchinova ◽

Sergey N. Illarioshkin

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Rapid Development ◽

Functional Integration ◽

Cell Loss ◽

Cell Replacement Therapy ◽

And Control ◽

The Brain

Neurogenesis is a key mechanism of brain development and plasticity, which is impaired in chronic neurodegeneration, including Parkinson’s disease. The accumulation of aberrant α-synuclein is one of the features of PD. Being secreted, this protein produces a prominent neurotoxic effect, alters synaptic plasticity, deregulates intercellular communication, and supports the development of neuroinflammation, thereby providing propagation of pathological events leading to the establishment of a PD-specific phenotype. Multidirectional and ambiguous effects of α-synuclein on adult neurogenesis suggest that impaired neurogenesis should be considered as a target for the prevention of cell loss and restoration of neurological functions. Thus, stimulation of endogenous neurogenesis or cell-replacement therapy with stem cell-derived differentiated neurons raises new hopes for the development of effective and safe technologies for treating PD neurodegeneration. Given the rapid development of optogenetics, it is not surprising that this method has already been repeatedly tested in manipulating neurogenesis in vivo and in vitro via targeting stem or progenitor cells. However, niche astrocytes could also serve as promising candidates for controlling neuronal differentiation and improving the functional integration of newly formed neurons within the brain tissue. In this review, we mainly focus on current approaches to assess neurogenesis and prospects in the application of optogenetic protocols to restore the neurogenesis in Parkinson’s disease.

Download Full-text

A Summary of Phenotypes Observed in the In Vivo Rodent Alpha-Synuclein Preformed Fibril Model

Journal of Parkinson s Disease ◽

10.3233/jpd-212847 ◽

2021 ◽

pp. 1-13

Author(s):

Nicole K. Polinski

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Study Design ◽

Alpha Synuclein ◽

Therapeutic Strategies ◽

Rodent Model ◽

In Vivo Model ◽

Nigrostriatal Degeneration ◽

The Brain

The use of wildtype recombinant alpha-synuclein preformed fibrils (aSyn PFFs) to induce endogenous alpha-synuclein to form pathological phosphorylation and trigger neurodegeneration is a popular model for studying Parkinson’s disease (PD) biology and testing therapeutic strategies. The strengths of this model lie in its ability torecapitulatethe phosphorylation/aggregationof aSyn and nigrostriatal degeneration seen in PD, as well as its suitability for studying the progressive nature of PD and the spread of aSyn pathology. Although the model is commonly used and has been adopted by many labs, variability in observed phenotypes exists. Here we provide summaries of the study design and reported phenotypes frompublished reports characterizing the aSyn PFF in vivo model in rodents following injection into the brain, gut, muscle, vein, peritoneum, and eye. These summariesare designed to facilitate an introduction to the use of aSyn PFFs to generate a rodent model of PD—highlighting phenotypes observed in papers that set out to thoroughly characterize the model.This information will hopefully improve the understanding of this model and clarify when the aSyn PFF model may be an appropriate choice for one’s research.

Download Full-text

Effect of glutamatergic systems on in vivo binding of [125I]?-CIT in the brain of a rat model of Parkinson's disease

Synapse ◽

10.1002/syn.10096 ◽

2002 ◽

Vol 46 (1) ◽

pp. 38-44 ◽

Cited By ~ 4

Author(s):

Shinya Kagawa ◽

Takayuki Nakano ◽

Osamu Inoue ◽

Tsunehiko Nishimura

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Rat Model ◽

In Vivo Binding ◽

The Brain

Download Full-text

Chronic dietary supplementation with turmeric protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-mediated neurotoxicity in vivo: implications for Parkinson's disease

British Journal Of Nutrition ◽

10.1017/s0007114510005817 ◽

2011 ◽

Vol 106 (1) ◽

pp. 63-72 ◽

Cited By ~ 14

Author(s):

Rajeswara Babu Mythri ◽

Jayagopalan Veena ◽

G. Harish ◽

B. S. Shankaranarayana Rao ◽

M. M. Srinivas Bharath

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Neurons ◽

Symptomatic Relief ◽

Dietary Supplementation ◽

Protein Nitration ◽

Dietary Consumption ◽

Midbrain Dopaminergic Neurons ◽

The Brain

Multiple pathways including oxidative stress and mitochondrial damage are implicated in neurodegeneration during Parkinson's disease (PD). The current PD drugs provide only symptomatic relief and have limitations in terms of adverse effects and inability to prevent neurodegeneration. Therefore, there is a demand for novel compound(s)/products that could target multiple pathways and protect the dying midbrain dopaminergic neurons, with potential utility as adjunctive therapy along with conventional drugs. Turmeric is a spice used in traditional Indian cuisine and medicine with antioxidant, anti-inflammatory and potential neuroprotective properties. To explore the neuroprotective property of turmeric in PD, mice were subjected to dietary supplementation with aqueous suspensions of turmeric for 3 months, mimicking its chronic consumption and challenged in vivo with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Brain samples from untreated and treated groups were characterised based on mitochondrial complex I (CI) activity, protein nitration and tyrosine hydroxylase immunoreactivity. Chronic turmeric supplementation induced the enzyme activity of γ-glutamyl cysteine ligase, which in turn increased glutathione levels and protected against peroxynitrite-mediated inhibition of brain CI. These mice were also protected against MPTP-mediated protein nitration, CI inhibition and degeneration of substantia nigra neurons in the brain. We conclude that chronic dietary consumption of turmeric protects the brain against neurotoxic insults, with potential application in neurodegeneration. Further characterisation of the active constituents of turmeric that potentially promote neuroprotection could improve the utility of dietary turmeric in brain function and disease.

Download Full-text