Phosphorylation of α-synuclein at T64 results in distinct oligomers and exerts toxicity in models of Parkinson's disease.

α-Synuclein accumulates in Lewy bodies, and this accumulation is a pathological hallmark of Parkinson's disease (PD). Previous studies have indicated a causal role of α-synuclein in the pathogenesis of PD. However, the molecular and cellular mechanisms of α-synuclein toxicity remain elusive. Here, we describe a novel phosphorylation site of α-synuclein at T64 and the detailed characteristics of this post-translational modification. T64 phosphorylation was enhanced in both PD models and human PD brains. T64D phosphomimetic mutation led to distinct oligomer formation, and the structure of the oligomer was similar to that of α-synuclein oligomer with A53T mutation. Such phosphomimetic mutation induced mitochondrial dysfunction, lysosomal disorder, and cell death in cells and neurodegeneration in vivo, indicating a pathogenic role of α-synuclein phosphorylation at T64 in PD.

Parkinson's disease-associated iPLA2-VIA/PLA2G6 regulates neuronal functions and α-synuclein stability through membrane remodeling.

Mutations in the iPLA2-VIA/PLA2G6 gene are responsible for PARK14-linked Parkinson's disease (PD) with α-synucleinopathy. However, it is unclear how iPLA2-VIA mutations lead to α-synuclein (α-Syn) aggregation and dopaminergic (DA) neurodegeneration. Here, we report that iPLA2-VIA-deficient Drosophila exhibits defects in neurotransmission during early developmental stages and progressive cell loss throughout the brain, including degeneration of the DA neurons. Lipid analysis of brain tissues reveals that the acyl-chain length of phospholipids is shortened by iPLA2-VIA loss, which causes endoplasmic reticulum (ER) stress through membrane lipid disequilibrium. The introduction of wild-type human iPLA2-VIA or the mitochondria-ER contact site-resident protein C19orf12 in iPLA2-VIA-deficient flies rescues the phenotypes associated with altered lipid composition, ER stress, and DA neurodegeneration, whereas the introduction of a disease-associated missense mutant, iPLA2-VIA A80T, fails to suppress these phenotypes. The acceleration of α-Syn aggregation by iPLA2-VIA loss is suppressed by the administration of linoleic acid, correcting the brain lipid composition. Our findings suggest that membrane remodeling by iPLA2-VIA is required for the survival of DA neurons and α-Syn stability.

Parkinson's disease with a typical clinical course of 17 years overlapped by Creutzfeldt-Jakob disease: an autopsy case report.

BACKGROUND: Late-stage Parkinson's disease (PD) often presents with neuropsychiatric symptoms such as dementia, psychosis, excessive daytime sleepiness, apathy, depression, and anxiety. However, neuropsychiatric symptoms are the cardinal features of Creutzfeldt-Jakob disease (CJD), raising the possibility that CJD may be an overlooked condition when it accompanies late-stage PD. CASE PRESENTATION: We describe a female autopsy case of PD with a typical clinical course of 17 years, in which CJD overlapped with PD during the final year of the patient's life. The patient died aged 85 years. Neuropathological features included widespread Lewy body-related α-synucleinopathy predominantly in the brainstem and limbic system, as well as the typical pathology of methionine/methionine type 1 CJD in the brain. CONCLUSIONS: Our case demonstrates the clinicopathological co-occurrence of PD and CJD in a sporadic patient. The possibility of mixed pathology, including prion pathology, should be taken into account when neuropsychiatric symptoms are noted during the disease course of PD.

Arylsulfatase A, a genetic modifier of Parkinson's disease, is an α-synuclein chaperone.

Mutations in lysosomal genes increase the risk of neurodegenerative diseases, as is the case for Parkinson's disease. Here, we found that pathogenic and protective mutations in arylsulfatase A (ARSA), a gene responsible for metachromatic leukodystrophy, a lysosomal storage disorder, are linked to Parkinson's disease. Plasma ARSA protein levels were changed in Parkinson's disease patients. ARSA deficiency caused increases in α-synuclein aggregation and secretion, and increases in α-synuclein propagation in cells and nematodes. Despite being a lysosomal protein, ARSA directly interacts with α-synuclein in the cytosol. The interaction was more extensive with protective ARSA variant and less with pathogenic ARSA variant than wild-type. ARSA inhibited the in vitro fibrillation of α-synuclein in a dose-dependent manner. Ectopic expression of ARSA reversed the α-synuclein phenotypes in both cell and fly models of synucleinopathy, the effects correlating with the extent of the physical interaction between these molecules. Collectively, these results suggest that ARSA is a genetic modifier of Parkinson's disease pathogenesis, acting as a molecular chaperone for α-synuclein.

Effects of donepezil dose escalation in Parkinson's patients with dementia receiving long-term donepezil treatment: an exploratory study.

BACKGROUND: The benefits of escalating the dose of donepezil in patients who are already receiving long-term treatment with it have not been well evaluated. Therefore, an exploratory study to assess the effects of donepezil dose escalation in patients with Parkinson's disease with dementia, and specifically on patients receiving long-term treatment with donepezil, was performed. METHODS: Patients treated with 5-mg/day donepezil for at least 3 months and having a Mini-Mental State Examination (MMSE) score between 10 and 26 were included in this study. Donepezil dosage was then increased to 10 mg/day for 12 weeks. The outcome measures were a modified form of the Neuropsychiatric Inventory (NPI) with an extra domain for additional evaluation of fluctuation in cognitive functions (NPI-11) and the MMSE. RESULTS: Of the nine patients enrolled, two withdrew because of nausea and inability to be assessed on the predetermined date; this left seven participants (four men and three women) with a mean age of 74.6 ± 6.9 years, a mean period of Parkinson's disease of 11.7 ± 7.5 years, and median donepezil use of 7 months (range: 3-56 months). At baseline, the mean total NPI-11 and mean MMSE scores were 18.3 ± 5.6 points and 21.3 ± 5.3 points, respectively. At week 12, they improved by 8.3 points (P < 0.01) and 3.0 points (P = 0.08), respectively, from the baseline. The NPI symptom domains that improved by 1 or more points were hallucination (1.3 points), depression (1.0 points), anxiety (1.6 points), and aberrant motor behaviour (1.7 points). None of the patients withdrew because of worsening of parkinsonism. CONCLUSIONS: The present results suggest that treatment with dose escalation of donepezil from 5 mg/day to 10 mg/day may be therapeutically useful for patients with Parkinson's disease with dementia who have taken donepezil 5 mg/day in the long term.

The effects of lactulose on constipation in patients with Parkinson's disease: An exploratory pilot study.

Introduction: Constipation is one of the most common non-motor symptoms of Parkinson's disease (PD) and is associated with reduced quality of life in patients with PD. The aim of this study was to evaluate the effect of lactulose on defecation status in patients with PD. Methods: In this open-label, single-center, exploratory pilot study, twenty-nine patients with PD received lactulose for three weeks for the treatment of constipation. The primary endpoint was the number of spontaneous bowel movements (SBMs). The secondary endpoints were stool consistency (Bristol Stool Form Scale [BSFS]) and the number of rescue laxatives used. Results: Twenty-five patients with PD completed the study. The number of SBMs recorded during the lactulose intervention period was significantly increased compared with that recorded during the pre-intervention period. During the intervention period, the BSFS scores of the patients increased significantly, whereas the number of rescue laxatives they used decreased significantly. No serious adverse events were observed during the study period. Lactulose was well-tolerated. Conclusions: The results of this study suggest that lactulose may be effective in improving defecation status in patients with PD. Further randomized controlled trials are needed to confirm the effects of lactulose on constipation in patients with PD.

[The questionnaire survey regarding the impact of COVID-19 pandemic on Parkinson's disease patients].

We conducted the multicenter questionnaire survey targeting patients with Parkinson's disease (PD) in order to investigate the impacts on their daily lives and their requests to hospitals in the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Mainly using open-ended questionnaire, we asked their anxiety, troubles they are facing, and requests toward hospitals in the pandemic of SARS-CoV-2. Two hundred fifth-eight PD patients answered the questionnaire. There were various opinions about anxiety such as "PD patients are susceptible and vulnerable to SARS-CoV-2" (36.8%). Concerning the troubles in the pandemic, the most frequent answer was that they couldn't participate in the rehabilitation and elderly day care (38.4%). Relatively many PD patients requested telemedicine (29.5%), whereas some people hoped face-to-face medical care (8.1%). There were demands about the delivery of medications (50.0%), the establishment of telephone consultations (43.8%), resources for rehabilitation at home (43.8%). The medical care adapted to the anxiety, trouble and requests of PD patients will be required in the era when we have to live with SARS-CoV-2.

DJ-1 associates with synaptic membranes.

Parkinson's disease (PD) is a neurodegenerative disorder caused by loss of dopaminergic neurons. Although many reports have suggested that genetic factors are implicated in the pathogenesis of PD, molecular mechanisms underlying selective dopaminergic neuronal degeneration remain unknown. DJ-1 is a causative gene for autosomal recessive form of PARK7-linked early-onset PD. A number of studies have demonstrated that exogenous DJ-1 localizes within mitochondria and the cytosol, and functions as a molecular chaperone, as a transcriptional regulator, and as a cell protective factor against oxidative stress. However, the precise subcellular localization and function of endogenous DJ-1 are not well known. The mechanisms by which mutations in DJ-1 contributes to neuronal degeneration also remain poorly understood. Here we show by immunocytochemistry that DJ-1 distributes to the cytosol and membranous structures in a punctate appearance in cultured cells and in primary neurons obtained from mouse brain. Interestingly, DJ-1 colocalizes with the Golgi apparatus proteins GM130 and the synaptic vesicle proteins such as synaptophysin and Rab3A. Förster resonance energy transfer analysis revealed that a small portion of DJ-1 interacts with synaptophysin in living cells. Although the wild-type DJ-1 protein directly associates with membranes without an intermediary protein, the pathogenic L166P mutation of DJ-1 exhibits less binding to synaptic vesicles. These results indicate that DJ-1 associates with membranous organelles including synaptic membranes to exhibit its normal function.

Synthesis and anti-migrative evaluation of moverastin derivatives.

Cell migration of tumor cells is essential for invasion of the extracellular matrix and for cell dissemination. Inhibition of the cell migration involved in the invasion process represents a potential therapeutic approach to the treatment of tumor metastasis; therefore, a novel series of derivatives of moverastins (moverastins A and B), an inhibitor of tumor cell migration, was designed and chemically synthesized. Among these moverastin derivatives, several compounds showed stronger cell migration inhibitory activity than parental moverastins, and UTKO1 was found to have the most potent inhibitory activity against the migration of human esophageal tumor EC17 cells in a chemotaxis cell chamber assay. Interestingly, although moverastins are considered to inhibit tumor cell migration by inhibiting farnesyltransferase (FTase), UTKO1 did not inhibit FTase, indicating that UTKO1 inhibited tumor cell migration by a mechanism other than the inhibition of FTase.

What can we learn from the effect of trihexyphenidyl on motor fluctuations during continuous levodopa-carbidopa intestinal gel infusion (LCIG)? - First documented case.

Motor fluctuations can be seen even during treatment with continuous levodopa-carbidopa intestinal gel infusion (LCIG). We report on a middle-aged man with advanced Parkinson's disease (PD) on LCIG in which motor fluctuations have been improved with an anticholinergic. To the best of our knowledge, there have been no previous LCIG cases reported with motor fluctuations responding to non-dopaminergic agent, which might reveal some clues to its pathophysiology. Long-term oral levodopa treatment is associated with development of potentially disabling motor complications including motor fluctuations and dyskinesias in the majority of patients with PD. It has been suggested that motor complications are related to the nonphysiological restoration of brain dopamine with intermittent administration of standard oral levodopa. LCIG significantly reduces "off" time and increases "on" time without dyskinesia in comparison to standard oral levodopa through consistent plasma concentration of levodopa to restore brain dopamine in a more physiological manner. However, it has been reported that PD patients on LCIG often worsen during the afternoon hours, even with stable plasma concentration of levodopa. This raises the possibility that additional factors to dopamine deficiency could play a role in occurrence of motor fluctuations. Here we offer a hypothesis that altered cholinergic signaling could also be involved in the pathophysiology of motor fluctuations, based on our clinical evidence that anticholinergic drug has eliminated motor fluctuations during LCIG in a patient with PD. Further studies for non-dopaminergic along with dopaminergic signaling may be needed to better understand the pathophysiological basis of motor complications in PD.

Pathogenesis of familial Parkinson's disease: new insights based on monogenic forms of Parkinson's disease.

Parkinson's disease (PD) is one of the most common movement disorders caused by the loss of dopaminergic neuronal cells. The molecular mechanisms underlying neuronal degeneration in PD remain unknown; however, it is now clear that genetic factors contribute to the pathogenesis of this disease. Approximately, 5% of patients with clinical features of PD have clear familial etiology, which show a classical recessive or dominant Mendelian mode of inheritance. Over the decade, more than 15 loci and 11 causative genes have been identified so far and many studies shed light on their implication in not only monogenic but also sporadic form of PD. Recent studies revealed that PD-associated genes play important roles in cellular functions, such as mitochondrial functions, ubiquitin-proteasomal system, autophagy-lysosomal pathway and membrane trafficking. Furthermore, the proteins encoded by PD-associated genes can interact with each other and such gene products may share a common pathway that leads to nigral degeneration. However, their precise roles in the disease and their normal functions remain poorly understood. In this study, we review recent progress in knowledge about the genes associated with familial PD.

Parkin stabilizes PINK1 through direct interaction.

Parkinson disease (PD) is the most common movement disorder and is characterized by dopaminergic dysfunction. The majority of PD cases are sporadic; however, the discovery of genes linked to rare familial forms of the disease has provided crucial insight into the molecular mechanisms of disease pathogenesis. Multiple genes mediating familial forms of Parkinson's disease (PD) have been identified, such as parkin (PARK2) and phosphatase and tensin homologue deleted on chromosome ten (PTEN)-induced putative kinase 1: PINK1 (PARK6). Here, we showed that Parkin directly interacts with PINK1, but did not bind to pathogenic PINK1 mutants. Parkin, but not its pathogenic mutants, stabilizes PINK1 by interfering with its degradation via the ubiquitin-mediated proteasomal pathway. In addition, the interaction between Parkin and PINK1 resulted in reciprocal reduction of their solubility. Our results indicate that Parkin regulates PINK1 stabilization via direct interaction with PINK1, and operates through a common pathway with PINK1 in the pathogenesis of early-onset PD.

Toxic effects of dopamine metabolism in Parkinson's disease.

Levodopa is the most effective medication for Parkinson's disease (PD). In contrast, there is evidence that levodopa and its metabolites such as dopa/dopamine quinone are toxic for nigral neurons based on in vitro studies. Moreover, there is growing evidence that oxidative stress and mitochondrial dysfunction contribute the pathogenesis of PD. Thus, studies for oxidative stress give us good information for elucidating the pathogenesis of PD. In this regard, it is mandatory to develop markers such as 4-hydroxy-nonenal (HNE). HNE is a product of lipid peroxidation. Indeed, immunohistochemical studies have revealed that HNE-modified proteins accumulate within ragged red fibers (RRFs). This finding indicated that mitochondrial impairment may be linked to oxidative stress. Moreover, HNE-modified proteins accumulate in nigral neurons. In PD, mitochondrial dysfunction such as complex I deficiency has also been reported. In addition, HNE can modify alpha-synuclein (SNCA). Subsequently, this modification may trigger the aggregation of this protein. At a minimum, this modification could be associated with oligomer formation or fibrillation of SNCA.

Familial Parkinsonism with digenic parkin and PINK1 mutations.

To clarify the genetic correlation between parkin and PINK1, we screened for PINK1 mutations in 175 parkinsonism patients with parkin mutations. We detected two sibling pairs and one sporadic patient carrying both parkin and PINK1 mutations. The age at onset of Parkinsonism of patients with the digenic mutations was lower than that of patients with the same parkin mutation alone. In addition, two of three patients carrying both parkin and PINK1 mutations had schizophrenia. These findings indicate that PINK1 mutation might modify parkin mutation-positive Parkinsonism, and PINK1 mutations might be associated with psychiatric disorders.

Visual impairment in Parkinson's disease treated with amantadine: case report and review of the literature.

A 61-year-old man with Parkinson's disease (PD) developed sudden-onset visual impairment after initiation of amantadine treatment. Ophthalmologic examination revealed corneal endothelial edema. Discontinuation of amantadine resulted in rapid improvement of visual acuity. A review of the literature indicated only a few reports of amantadine-associated corneal dysfunction in patients with neurological disorders as well as influenza syndrome, but none with PD. Amantadine-associated visual impairment in PD could be possibly overlooked, since PD mainly affects elderly people who often develop aging-related ocular changes. The present report alerts neurologists and physicians in general to the peculiar ophthalmologic side effect of amantadine.

[The pathogenesis of Parkinson's disease: a hint from insights of familial Parkinson's disease].

Parkinson's disease (PD) is a progressive movement disorder characterized by resting tremor, rigidity, akinesia, and postural instability. In addition, PD is characterized by the appearance of Lewy bodies in the remaining neurons. The exact etiology for this disease is still unknown. However, genetic-environmental interaction could contribute the pathomechanisms of PD. Indeed, totally seven causative genes responsible for familial PD have been identified. Since discovery of familial PD (FPD), genetic PD models have been developed. Thus, we think that the research field of FPD provides us a good hint for the pathogenesis of nigral degeneration in not only familial but also sporadic form of PD.

Anhedonia and its correlation with clinical aspects in Parkinson's disease.

Anhedonia is one of the non-motor symptoms observed in the Parkinson's disease (PD). However, there is no clear relationship between anhedonia and its correlation with other symptoms of PD. The aim of this study is to evaluate the characteristics of anhedonia and its correlation with clinical aspects of PD in a relatively large cohort. We enrolled 318 patients with PD and 62 control subjects for this study. Patients and subjects were tested using the Snaith-Hamilton Pleasure Scale Japanese version and the Beck Depression Inventory 2nd edition for the assessment of anhedonia and depression. We also investigated the correlation among clinical aspects of PD, anhedonia, and depression in patients with PD. The Snaith-Hamilton Pleasure Scale Japanese version and the Beck Depression Inventory 2nd edition scores were significantly higher in patients with PD than in control subjects (p=0.03 and p=0.0006, respectively). All PD patients with anhedonia had a significantly higher score on the unified Parkinson's disease rating scale (UPDRS) parts I and II compared to PD patients without anhedonia. Additionally, all PD patients with depression scored significantly higher on UPDRS part I-IV than PD patients without depression. The patients with anhedonia and without depression had mild motor severity and their treatment was relatively low dosage. These results suggest that anhedonia and depression are slightly linked, but not the same. PD patients with only anhedonia may be closely linked apathy found in untreated early stages of PD.

Membrane lipids as therapeutic targets for Parkinson's disease: a possible link between Lewy pathology and membrane lipids.

INTRODUCTION: Pathologically, Parkinson's disease (PD) is characterized by nigral cell loss and Lewy pathology in the remaining neurons. Whereas the motor symptoms of PD show a marked response to dopamine replacement therapy, many of the non-motor symptoms are resistant to treatment. This suggests that in addition to nigral cell loss, widespread Lewy pathology in the nervous system is associated with the manifestations of PD. Areas covered: Although the mechanism of Lewy body formation remains largely unknown, it is becoming clear that changes in the behavior of α-synuclein are critical in this process. α-Synuclein behaves differently depending on the lipid composition of membranes with which it interacts; therefore, one can postulate that the altered lipid composition of neuronal membranes may lead to Lewy pathology. The lipid composition of cellular membranes is consistently altered in the brains of patients with PD, and Lewy pathology is a common feature of several human lipidoses with mutations in enzymes that affect membrane lipids. This further supports the concept that alterations in the membrane lipids of neurons are central to Lewy pathology. Expert opinion: This concept provides a new platform to establish models for the development of novel treatments for PD.

A Japanese multicenter survey characterizing pain in Parkinson's disease.

BACKGROUND: Pain is a frequent, troublesome symptom of PD but is under-recognized and poorly understood. AIM: We characterized pain prevalence, severity, and location in PD, to better understand its pathophysiology and improve diagnosis and treatment. SUBJECTS AND METHODS: A cross-sectional controlled study was conducted at 19 centers across Japan. A total of 632 subjects with Mini-Mental State Examination scores ≥24 were enrolled, including 324 PD patients and 308 controls. Sex and mean age did not differ between the two groups. Demographic and clinical data were collected. Pain was assessed using questionnaires, the SF-36v2 bodily pain scale, and a body illustration for patients to indicate the location of pain in 45 anatomical areas. RESULTS: Pain prevalence in the PD group was 78.6%, significantly higher than in controls (49.0%), as was its severity. There was no correlation between SF-36v2 score and motor scores, such as Unified Parkinson's Disease Rating Scale III or Hoehn & Yahr scores. Pain distribution was similar between groups, predominantly in the lower back, followed by the gluteal region, lower legs, thighs, posterior neck, and shoulders. CONCLUSION: Pain is a significant problem in the Japanese PD population and we discuss its pathophysiology.

Lipid rafts mediate the synaptic localization of alpha-synuclein.

Alpha-synuclein contributes to the pathogenesis of Parkinson's disease (PD), but its precise role in the disorder and its normal function remain poorly understood. Consistent with a presumed role in neurotransmitter release and its prominent deposition in the dystrophic neurites of PD, alpha-synuclein localizes almost exclusively to the nerve terminal. In brain extracts, however, alpha-synuclein behaves as a soluble, monomeric protein. Using a binding assay to characterize the association of alpha-synuclein with cell membranes, we find that alpha-synuclein binds saturably and with high affinity to characteristic intracellular structures that double label for components of lipid rafts. Biochemical analysis demonstrates the interaction of alpha-synuclein with detergent-resistant membranes and reveals a shift in electrophoretic mobility of the raft-associated protein. In addition, the A30P mutation associated with PD disrupts the interaction of alpha-synuclein with lipid rafts. Furthermore, we find that both the A30P mutation and raft disruption redistribute alpha-synuclein away from synapses, indicating an important role for raft association in the normal function of alpha-synuclein and its role in the pathogenesis of PD.