Altered levels of α-synuclein and sphingolipids in Batten disease lymphoblast cells

Increased SNAI2 expression and defective collagen adhesion in cells with pediatric dementia, juvenile ceroid lipofuscinosis

Dementia-related neurodegenerative diseases (NDDs), including Alzheimer's disease (AD), are known to be caused by accumulation of toxic proteins. However, the molecular mechanisms that cause neurodegeneration and its biophysical effects on cells remain unclear. In this study, we used juvenile neuronal ceroid lipofuscinosis (JNCL), a pediatric dementia with a clear etiology of mutations in ceroid lipofuscinosis neuronal 3 (CLN3), to explore the changes in cell adhesion, a biophysical process that regulates neuronal development and survival. We used JNCL cerebral organoid gene expression datasets to identify the biological pathways that affect neural development, and found enriched gene expression in the epithelial-mesenchymal transition (EMT) pathway and increased expression of its inducer snail family transcriptional repressor 2 (SNAI2). A cell adhesion assay using lymphoblasts from patients with JNCL revealed defective adhesion to cell culture plates, glass surfaces, collagen type I, and neuroblast-like cells. To determine whether inhibition of EMT could improve the cell adhesion of JNCL lymphoblasts, we used all-trans retinoic acid, a well-known EMT inhibitor and inducer of neural differentiation. In JNCL lymphoblasts, ATRA treatment enhanced adhesion to collagen type I and these effects were abolished by Ca2+ chelator. These results provide new insights into the role of CLN3 and cell adhesion in the pathogenesis of NDD.

Mutant mice with rod-specific VPS35 deletion exhibit retinal α-synuclein pathology-associated degeneration

Vacuolar protein sorting 35 (VPS35), the core component of the retromer complex which regulates endosomal trafficking, is genetically linked with Parkinson's disease (PD). Impaired vision is a common non-motor manifestation of PD. Here, we show mouse retinas with VPS35-deficient rods exhibit synapse loss and visual deficit, followed by progressive degeneration concomitant with the emergence of Lewy body-like inclusions and phospho-α-synuclein (P-αSyn) aggregation. Ultrastructural analyses reveal VPS35-deficient rods accumulate aggregates in late endosomes, deposited as lipofuscins bound to P-αSyn. Mechanistically, we uncover a protein network of VPS35 and its interaction with HSC70. VPS35 deficiency promotes sequestration of HSC70 and P-αSyn aggregation in late endosomes. Microglia which engulf lipofuscins and P-αSyn aggregates are activated, displaying autofluorescence, observed as bright dots in fundus imaging of live animals, coinciding with pathology onset and progression. The Rod∆Vps35 mouse line is a valuable tool for further mechanistic investigation of αSyn lesions and retinal degenerative diseases.

Distinct sets of lysosomal genes define synucleinopathy and tauopathy

Neurodegenerative diseases are characterized by distinct protein aggregates, such as those of α-synuclein and tau. Lysosomal defect is a key contributor to the accumulation and propagation of aberrant protein aggregates in these diseases. The discoveries of common proteinopathies in multiple forms of lysosomal storage diseases (LSDs) and the identification of some LSD genes as susceptible genes for those proteinopathies suggest causative links between LSDs and the proteinopathies. The present study hypothesized that defects in lysosomal genes will differentially affect the propagation of α-synuclein and tau proteins, thereby determining the progression of a specific proteinopathy. We established an imaging-based high-contents screening (HCS) system in Caenorhabditis elegans (C. elegans) model, by which the propagation of α-synuclein or tau is measured by fluorescence intensity. Using this system, we performed RNA interference (RNAi) screening to induce a wide range of lysosomal malfunction through knock down of 79 LSD genes, and to obtain the candidate genes with significant change in protein propagation. While some LSD genes commonly affected both α-synuclein and tau propagation, our study identified the distinct sets of LSD genes that differentially regulate the propagation of either α-synuclein or tau. The specificity and efficacy of these LSD genes were retained in the disease-related phenotypes, such as pharyngeal pumping behavior and life span. This study suggests that distinct lysosomal genes differentially regulate the propagation of α-synuclein and tau, and offer a steppingstone to understanding disease specificity. [BMB Reports 2023; 56(12): 657-662].

Alpha-Synuclein in Peripheral Tissues as a Possible Marker for Neurological Diseases and Other Medical Conditions

The possible usefulness of alpha-synuclein (aSyn) determinations in peripheral tissues (blood cells, salivary gland biopsies, olfactory mucosa, digestive tract, skin) and in biological fluids, except for cerebrospinal fluid (serum, plasma, saliva, feces, urine), as a marker of several diseases, has been the subject of numerous publications. This narrative review summarizes data from studies trying to determine the role of total, oligomeric, and phosphorylated aSyn determinations as a marker of various diseases, especially PD and other alpha-synucleinopathies. In summary, the results of studies addressing the determinations of aSyn in its different forms in peripheral tissues (especially in platelets, skin, and digestive tract, but also salivary glands and olfactory mucosa), in combination with other potential biomarkers, could be a useful tool to discriminate PD from controls and from other causes of parkinsonisms, including synucleinopathies.

The ER calcium channel Csg2 integrates sphingolipid metabolism with autophagy

Sphingolipids are ubiquitous components of membranes and function as bioactive lipid signaling molecules. Here, through genetic screening and lipidomics analyses, we find that the endoplasmic reticulum (ER) calcium channel Csg2 integrates sphingolipid metabolism with autophagy by regulating ER calcium homeostasis in the yeast Saccharomyces cerevisiae. Csg2 functions as a calcium release channel and maintains calcium homeostasis in the ER, which enables normal functioning of the essential sphingolipid synthase Aur1. Under starvation conditions, deletion of Csg2 causes increases in calcium levels in the ER and then disturbs Aur1 stability, leading to accumulation of the bioactive sphingolipid phytosphingosine, which specifically and completely blocks autophagy and induces loss of starvation resistance in cells. Our findings indicate that calcium homeostasis in the ER mediated by the channel Csg2 translates sphingolipid metabolism into autophagy regulation, further supporting the role of the ER as a signaling hub for calcium homeostasis, sphingolipid metabolism and autophagy.

Juvenile CLN3 disease is a lysosomal cholesterol storage disorder: similarities with Niemann-Pick type C disease

BACKGROUND

The most common form of neuronal ceroid lipofuscinosis (NCL) is juvenile CLN3 disease (JNCL), a currently incurable neurodegenerative disorder caused by mutations in the CLN3 gene. Based on our previous work and on the premise that CLN3 affects the trafficking of the cation-independent mannose-6 phosphate receptor and its ligand NPC2, we hypothesised that dysfunction of CLN3 leads to the aberrant accumulation of cholesterol in the late endosomes/lysosomes (LE/Lys) of JNCL patients' brains.

METHODS

An immunopurification strategy was used to isolate intact LE/Lys from frozen autopsy brain samples. LE/Lys isolated from samples of JNCL patients were compared with age-matched unaffected controls and Niemann-Pick Type C (NPC) disease patients. Indeed, mutations in NPC1 or NPC2 result in the accumulation of cholesterol in LE/Lys of NPC disease samples, thus providing a positive control. The lipid and protein content of LE/Lys was then analysed using lipidomics and proteomics, respectively.

FINDINGS

Lipid and protein profiles of LE/Lys isolated from JNCL patients were profoundly altered compared to controls. Importantly, cholesterol accumulated in LE/Lys of JNCL samples to a comparable extent than in NPC samples. Lipid profiles of LE/Lys were similar in JNCL and NPC patients, except for levels of bis(monoacylglycero)phosphate (BMP). Protein profiles detected in LE/Lys of JNCL and NPC patients appeared identical, except for levels of NPC1.

INTERPRETATION

Our results support that JNCL is a lysosomal cholesterol storage disorder. Our findings also support that JNCL and NPC disease share pathogenic pathways leading to aberrant lysosomal accumulation of lipids and proteins, and thus suggest that the treatments available for NPC disease may be beneficial to JNCL patients. This work opens new avenues for further mechanistic studies in model systems of JNCL and possible therapeutic interventions for this disorder.

FUNDING

San Francisco Foundation.

Batten disease through different in vivo and in vitro models: A review

Batten disease consists of a family of primarily autosomal recessive, progressive neuropediatric disorders, also known as neuronal ceroid lipofuscinoses (NCLs). These pathologies are characterized by seizures and visual, cognitive and motor decline, and premature death. The pathophysiology of this rare disease is still unclear despite the years of trials and financial aids. This paper has reviewed advantages and limits of in vivo and in vitro models of Batten disease from murine and larger animal models to primitive unicellular models, until the most recently developed patient-derived induced pluripotent stem cells. For each model advantages, limits and applications were analyzed. The first prototypes investigated were murine models that due to their limits were replaced by larger animals. In vitro models gradually replaced animal models for practical, cost, and ethical reasons. Using induced pluripotent stem cells to study neurodegeneration is a new way of studying the disease, since they can be distinguished into differentiating elements like neurons, which are susceptible to neurodegeneration. In vivo and in vitro models have contributed to clarifying to some extent the pathophysiology of the disease. The collection and sharing of suitable human bio samples likely through biobanks can contribute to a better understanding, prevention, and to identify possible treatment strategies of Batten disease.

Targetable Pathways for Alleviating Mitochondrial Dysfunction in Neurodegeneration of Metabolic and Non-Metabolic Diseases

Many neurodegenerative and inherited metabolic diseases frequently compromise nervous system function, and mitochondrial dysfunction and oxidative stress have been implicated as key events leading to neurodegeneration. Mitochondria are essential for neuronal function; however, these organelles are major sources of endogenous reactive oxygen species and are vulnerable targets for oxidative stress-induced damage. The brain is very susceptible to oxidative damage due to its high metabolic demand and low antioxidant defence systems, therefore minimal imbalances in the redox state can result in an oxidative environment that favours tissue damage and activates neuroinflammatory processes. Mitochondrial-associated molecular pathways are often compromised in the pathophysiology of neurodegeneration, including the parkin/PINK1, Nrf2, PGC1α, and PPARγ pathways. Impairments to these signalling pathways consequently effect the removal of dysfunctional mitochondria, which has been suggested as contributing to the development of neurodegeneration. Mitochondrial dysfunction prevention has become an attractive therapeutic target, and there are several molecular pathways that can be pharmacologically targeted to remove damaged mitochondria by inducing mitochondrial biogenesis or mitophagy, as well as increasing the antioxidant capacity of the brain, in order to alleviate mitochondrial dysfunction and prevent the development and progression of neurodegeneration in these disorders. Compounds such as natural polyphenolic compounds, bioactive quinones, and Nrf2 activators have been reported in the literature as novel therapeutic candidates capable of targeting defective mitochondrial pathways in order to improve mitochondrial function and reduce the severity of neurodegeneration in these disorders.

Loss of CLN3, the gene mutated in juvenile neuronal ceroid lipofuscinosis, leads to metabolic impairment and autophagy induction in retinal pigment epithelium

Juvenile neuronal ceroid lipofuscinosis (JNCL, aka. juvenile Batten disease or CLN3 disease) is a lysosomal storage disease characterized by progressive blindness, seizures, cognitive and motor failures, and premature death. JNCL is caused by mutations in the Ceroid Lipofuscinosis, Neuronal 3 (CLN3) gene, whose function is unclear. Although traditionally considered a neurodegenerative disease, CLN3 disease displays eye-specific effects: Vision loss not only is often one of the earliest symptoms of JNCL, but also has been reported in non-syndromic CLN3 disease. Here we described the roles of CLN3 protein in maintaining healthy retinal pigment epithelium (RPE) and normal vision. Using electroretinogram, fundoscopy and microscopy, we showed impaired visual function, retinal autofluorescent lesions, and RPE disintegration and metaplasia/hyperplasia in a Cln3 ~ 1 kb-deletion mouse model [1] on C57BL/6J background. Utilizing a combination of biochemical analyses, RNA-Seq, Seahorse XF bioenergetic analysis, and Stable Isotope Resolved Metabolomics (SIRM), we further demonstrated that loss of CLN3 increased autophagic flux, suppressed mTORC1 and Akt activities, enhanced AMPK activity, and up-regulated gene expression of the autophagy-lysosomal system in RPE-1 cells, suggesting autophagy induction. This CLN3 deficiency induced autophagy induction coincided with decreased mitochondrial oxygen consumption, glycolysis, the tricarboxylic acid (TCA) cycle, and ATP production. We also reported for the first time that loss of CLN3 led to glycogen accumulation despite of impaired glycogen synthesis. Our comprehensive analyses shed light on how loss of CLN3 affect autophagy and metabolism. This work suggests possible links among metabolic impairment, autophagy induction and lysosomal storage, as well as between RPE atrophy/degeneration and vision loss in JNCL.

Cellular models of Batten disease

The Neuronal Ceroid Lipofuscinoses (NCL), otherwise known as Batten disease, are a group of neurodegenerative diseases caused by mutations in 13 known genes. All except one NCL is autosomal recessive in inheritance, with similar aetiology and characterised by the accumulation of autofluorescent storage material in the lysosomes of cells. Age of onset and the rate of progression vary between the NCLs. They are collectively one of the most common lysosomal storage diseases, but the enigma remains of how genetically distinct diseases result in such remarkably similar pathogenesis. Much has been learnt from cellular studies about the function of the proteins encoded by the affected genes. Such research has utilised primitive unicellular models such as yeast and amoeba containing gene orthologues, cells derived from naturally occurring (sheep) and genetically engineered (mouse) animal models or patient-derived cells. Most recently, patient-derived induced pluripotent stem cell (iPSC) lines have been differentiated into neural cell-types to study molecular pathogenesis in the cells most profoundly affected by disease. Here, we review how cell models have informed much of the biochemical understanding of the NCLs and how more complex models are being used to further this understanding and potentially act as platforms for therapeutic efficacy studies in the future.

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Developments made in cellular models for neuronal ceroid lipofuscinosis (NCL) in basic biology and use as therapeutic platforms.

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Cellular models elucidating function of NCL proteins.

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NCL proteins implicated in the mTor signalling pathway.

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Patient-derived induced pluripotent stem cell (iPSC) lines have been differentiated into neural cell-types providing insights into the molecular pathogenesis of NCL.

Autophagy-lysosome pathway alterations and alpha-synuclein up-regulation in the subtype of neuronal ceroid lipofuscinosis, CLN5 disease

Neuronal ceroid lipofuscinoses (NCLs) are a group of inherited neurodegenerative lysosomal storage disorders. CLN5 deficiency causes a subtype of NCL, referred to as CLN5 disease. CLN5 is a soluble lysosomal protein with an unclear function in the cell. Increased levels of the autophagy marker protein LC3-II have been reported in several subtypes of NCLs. In this report, we examine whether autophagy is altered in CLN5 disease. We found that the basal level of LC3-II was elevated in both CLN5 disease patient fibroblasts and CLN5-deficient HeLa cells. Further analysis using tandem fluorescent mRFP-GFP-LC3 showed the autophagy flux was increased. We found the alpha-synuclein (α-syn) gene SNCA was highly up-regulated in CLN5 disease patient fibroblasts. The aggregated form of α-syn is well known for its role in the pathogenicity of Parkinson's disease. Higher α-syn protein levels confirmed the SNCA up-regulation in both patient cells and CLN5 knockdown HeLa cells. Furthermore, α-syn was localized to the vicinity of lysosomes in CLN5 deficient cells, indicating it may have a lysosome-related function. Intriguingly, knocking down SNCA reversed lysosomal perinuclear clustering caused by CLN5 deficiency. These results suggest α-syn may affect lysosomal clustering in non-neuronal cells, similar to its role in presynaptic vesicles in neurons.

Altered Expression of Ganglioside Metabolizing Enzymes Results in GM3 Ganglioside Accumulation in Cerebellar Cells of a Mouse Model of Juvenile Neuronal Ceroid Lipofuscinosis

Juvenile neuronal ceroid lipofuscinosis (JNCL) is caused by mutations in the CLN3 gene. Most JNCL patients exhibit a 1.02 kb genomic deletion removing exons 7 and 8 of this gene, which results in a truncated CLN3 protein carrying an aberrant C-terminus. A genetically accurate mouse model (Cln3^Δex7/8 mice) for this deletion has been generated. Using cerebellar precursor cell lines generated from wildtype and Cln3^Δex7/8 mice, we have here analyzed the consequences of the CLN3 deletion on levels of cellular gangliosides, particularly GM3, GM2, GM1a and GD1a. The levels of GM1a and GD1a were found to be significantly reduced by both biochemical and cytochemical methods. However, quantitative high-performance liquid chromatography analysis revealed a highly significant increase in GM3, suggesting a metabolic blockade in the conversion of GM3 to more complex gangliosides. Quantitative real-time PCR analysis revealed a significant reduction in the transcripts of the interconverting enzymes, especially of β-1,4-N-acetyl-galactosaminyl transferase 1 (GM2 synthase), which is the enzyme converting GM3 to GM2. Thus, our data suggest that the complex a-series gangliosides are reduced in Cln3^Δex7/8 mouse cerebellar precursor cells due to impaired transcription of the genes responsible for their synthesis.

[Mutation del 1,02kb in the CLN3 gene and extrapyramidal syndrome]

Mutations in the GBA and SMPD1 genes, which lead to the development of lysosomal storage diseases, are high risk factors for Parkinson's disease and dementia with Lewy bodies. We screened the mutations in the GALC and CLN3 genes in patients with Parkinson's disease and control subjects. A heterozygous CLN3 mutation (del 1.02 kb) carrier with clinical features of the unusual extrapyramidal syndrome was identified. A role of CLN3 mutations in the development of neurodegenerative disorders is discussed.

Protection against Experimental Stroke by Ganglioside GM1 Is Associated with the Inhibition of Autophagy

Ganglioside GM1, which is particularly abundant in the central nervous system (CNS), is closely associated with the protection against several CNS disorders. However, controversial findings have been reported on the role of GM1 following ischemic stroke. In the present study, using a rat middle cerebral artery occlusion (MCAO) model, we investigated whether GM1 can protect against ischemic brain injury and whether it targets the autophagy pathway. GM1 was delivered to Sprague-Dawley male rats at 3 doses (25 mg/kg, 50 mg/kg, 100 mg/kg) by intraperitoneal injection soon after reperfusion and then once daily for 2 days. The same volume of saline was given as a control. Tat–Beclin-1, a specific autophagy inducer, was administered by intraperitoneal injection at 24 and 48 hours post-MCAO. Infarction volume, mortality and neurological function were assessed at 72 hours after ischemic insult. Immunofluorescence and Western blotting were performed to determine the expression of autophagy-related proteins P62, LC3 and Beclin-1 in the penumbra area. No significant changes in mortality and physiological variables (heart rate, blood glucose levels and arterial blood gases) were observed between the different groups. However, MCAO resulted in enhanced conversion of LC3-I into LC3-II, P62 degradation, high levels of Beclin-1, a large area infarction (26.3±3.6%) and serious neurobehavioral deficits. GM1 (50 mg/kg) treatment significantly reduced the autophagy activation, neurobehavioral dysfunctions, and infarction volume (from 26.3% to 19.5%) without causing significant adverse side effects. However, this biological function could be abolished by Tat–Beclin-1. In conclusion: GM1 demonstrated safe and robust neuroprotective effects that are associated with the inhibition of autophagy following experimental stroke.

Autophagic flux and autophagosome morphogenesis require the participation of sphingolipids

Apoptosis and autophagy are two evolutionary conserved processes that exert a critical role in the maintenance of tissue homeostasis. While apoptosis is a tightly regulated cell program implicated in the removal of damaged or unwanted cells, autophagy is a cellular catabolic pathway that is involved in the lysosomal degradation and recycling of proteins and organelles, and is thereby considered an important cytoprotection mechanism. Sphingolipids (SLs), which are ubiquitous membrane lipids in eukaryotes, participate in the generation of various membrane structures, including lipid rafts and caveolae, and contribute to a number of cellular functions such as cell proliferation, apoptosis and, as suggested more recently, autophagy. For instance, SLs are hypothesized to be involved in several intracellular processes, including organelle membrane scrambling, whilst at the plasma membrane lipid rafts, acting as catalytic domains, strongly contribute to the ignition of critical signaling pathways determining cell fate. In particular, by targeting several shared regulators, ceramide, sphingosine-1-phosphate, dihydroceramide, sphingomyelin and gangliosides seem able to differentially regulate the autophagic pathway and/or contribute to the autophagosome formation. This review illustrates recent studies on this matter, particularly lipid rafts, briefly underscoring the possible implication of SLs and their alterations in the autophagy disturbances and in the pathogenesis of some human diseases.

Fibrates inhibit the apoptosis of Batten disease lymphoblast cells via autophagy recovery and regulation of mitochondrial membrane potential

Batten disease (BD; also known as juvenile neuronal ceroid lipofuscinosis) is a genetic disorder inherited as an autosomal recessive trait and is characterized by blindness, seizures, cognitive decline, and early death resulting from the inherited mutation of the CLN3 gene. Mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, disrupted autophagy, and enhanced apoptosis have been suggested to play a role in BD pathogenesis. Fibrates, a class of lipid-lowering drugs that induce peroxisome proliferator-activated receptor-α (PPAR-α) activation, are the most commonly used PPAR agonists. Assuming that fibrates have a neuroprotective effect, we studied the effects of fibrates, fenofibrate, bezafibrate, and gemfibrozil on apoptosis, depolarization of mitochondrial membrane, and defective autophagy in BD lymphoblast cells. The viability of fibrate-treated BD lymphoblast cells increased to levels of normal lymphoblast cells. In addition, treatment with fibrates inhibited depolarization of mitochondrial membrane potential in BD lymphoblast cells. Defective autophagy in BD lymphoblast cells was normalized when treated with fibrates as indicated by increased acridine orange staining. The recovery of autophagy in BD lymphoblast cells is most likely attributed to the upregulation of autophagy proteins, lysosomal-associated membrane protein 1 (LAMP1), and LC3 I/II, after treatment with fibrates. This study therefore suggests that fibrates may have a therapeutic potential against BD.

A central role for TOR signalling in a yeast model for juvenile CLN3 disease

Yeasts provide an excellent genetically tractable eukaryotic system for investigating the function of genes in their biological context, and are especially relevant for those conserved genes that cause disease. We study the role of btn1, the orthologue of a human gene that underlies an early onset neurodegenerative disease (juvenile CLN3 disease, neuronal ceroid lipofuscinosis (NCLs) or Batten disease) in the fission yeast Schizosaccharomyces pombe. A global screen for genetic interactions with btn1 highlighted a conserved key signalling hub in which multiple components functionally relate to this conserved disease gene. This signalling hub includes two major mitogen-activated protein kinase (MAPK) cascades, and centers on the Tor kinase complexes TORC1 and TORC2. We confirmed that yeast cells modelling CLN3 disease exhibit features consistent with dysfunction in the TORC pathways, and showed that modulating TORC function leads to a comprehensive rescue of defects in this yeast disease model. The same pathways may be novel targets in the development of therapies for the NCLs and related diseases.

Cell biology of the NCL proteins: What they do and don't do

The fatal, primarily childhood neurodegenerative disorders, neuronal ceroid lipofuscinoses (NCLs), are currently associated with mutations in 13 genes. The protein products of these genes (CLN1 to CLN14) differ in their function and their intracellular localization. NCL-associated proteins have been localized mostly in lysosomes (CLN1, CLN2, CLN3, CLN5, CLN7, CLN10, CLN12 and CLN13) but also in the Endoplasmic Reticulum (CLN6 and CLN8), or in the cytosol associated to vesicular membranes (CLN4 and CLN14). Some of them such as CLN1 (palmitoyl protein thioesterase 1), CLN2 (tripeptidyl-peptidase 1), CLN5, CLN10 (cathepsin D), and CLN13 (cathepsin F), are lysosomal soluble proteins; others like CLN3, CLN7, and CLN12, have been proposed to be lysosomal transmembrane proteins. In this review, we give our views and attempt to summarize the proposed and confirmed functions of each NCL protein and describe and discuss research results published since the last review on NCL proteins. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".

The neuronal ceroid lipofuscinoses: Opportunities from model systems

The neuronal ceroid lipofuscinoses are a group of severe and progressive neurodegenerative disorders, generally with childhood onset. Despite the fact that these diseases remain fatal, significant breakthroughs have been made in our understanding of the genetics that underpin these conditions. This understanding has allowed the development of a broad range of models to study disease processes, and to develop new therapeutic approaches. Such models have contributed significantly to our knowledge of these conditions. In this review we will focus on the advantages of each individual model, describe some of the contributions the models have made to our understanding of the broader disease biology and highlight new techniques and approaches relevant to the study and potential treatment of the neuronal ceroid lipofuscinoses. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".

Increased plasma oligomeric alpha-synuclein in patients with lysosomal storage diseases

A link between lysosomal storage diseases (LSDs) and neurodegenerative disorders associated with accumulation of presynaptic protein alpha-synuclein has been shown. Particularly, Gaucher disease (GD) patients with a deficiency of the lysosomal enzyme glucocerebrosidase (GBA) and carriers of GBA mutations are at increased risk of Parkinson's disease (PD). It remains unclear whether this link is due to increased alpha-synuclein oligomerization. Here we show that level of oligomeric alpha-synuclein form, associated with PD development, is increased in plasma of GD patients (n=41, median=22.9pg/mL, range1.57-444.58pg/mL; controls (n=40, median=6.02pg/mL, range 1.05-103.14pg/mL, p<0.0001). This difference is absent in GD patients receiving enzyme replacement therapy (ERT) for more than 5 years. Moreover, the levels of alpha-synuclein oligomers in plasma are also higher in patients with other LSDs (Niemann-Pick type C, Krabbe disease, Wolman disease) compared to the median value in controls. Therefore, we suggest that mutations in the GBA gene and at least in several other LSDs genes may be associated with an increase in oligomeric alpha-synuclein in plasma. ERT applied for recovering of GBA functions in GD treatment might decrease formation of plasma oligomeric alpha-synuclein.