Humans ; alpha-Synuclein/genetics* ; Parkinson Disease/pathology*

Parkinson's disease (PD) is a multifaceted disease in which environmental variables combined with genetic predisposition cause dopaminergic (DAergic) neuron loss in the substantia nigra pars compacta. The mutation of leucine-rich repeat kinase 2 (Lrrk2) is the most common autosomal dominant mutation in PD, and it has also been reported in sporadic cases. A growing body of research suggests that circadian rhythm disruption, particularly sleep-wake abnormality, is common during the early phase of PD. Our present study aimed to evaluate the impact of sleep deprivation (SD) on motor ability, sleep performance, and PD pathologies in Lrrk2^G2019S transgenic mice. After two months of SD, Lrrk2^G2019S mice at 12 months of age showed an exacerbated PD-like phenotype with motor deficits, a reduced striatal DA level, degenerated DAergic neurons, and altered sleep structure and biological rhythm accompanied by the decreased protein expression level of circadian locomotor output cycles kaput Lrrk2 gene in the brain. All these changes persisted and were even more evident in 18-month-old mice after 6 months of follow-up. Moreover, a significant increase in α-synuclein aggregation was found in SD-treated transgenic mice at 18 months of age. Taken together, our findings indicate that sleep abnormalities, as a risk factor, may contribute to the pathogenesis and progression of PD. Early detection of sleep disorders and improvement of sleep quality may help to delay disease progression and provide long-term clinical benefits.
Animals ; Electroencephalography ; Leucine/genetics* ; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics* ; Mice ; Mice, Transgenic ; Mutation ; Parkinson Disease/metabolism* ; Sleep Deprivation/complications* ; alpha-Synuclein/genetics*

OBJECTIVETo investigate the effect of curcumin on oligomer formation and mitochondrial ATP-sensitive potassium channels (mitoKATP) induced by overexpression or mutation of α-synuclein.

METHODSRecombinant plasmids α-synuclein-pEGFP-A53T and α-synuclein-pEGFP-WT were transfected into PC12 cells by lipofectamin method, and intervened by application of curcumin (20 μmol/L) and 5-hydroxydecanoate (5-HD). Oligomer formation in the cultured cells was identified by Western blotting and Dot blotting. Cytotoxicity and apoptosis of the PC12 cells were measured by lactate dehydrogenase (LDH) and JC-1 assays. mitoKATP were identified by Western blotting and whole cell patch clamp.

RESULTSCurcumin has significantly reduced the oligomer formation induced by overexpression or mutation of &alpha;-synuclein in the cultured cells. LDH has decreased by 36.3% and 23.5%, and red/green fluorescence ratio of JC-1 was increased respectively by 48.46% and 50.33% after application of curcumin (P<0.05). Protein expression of Kir6.2 has decreased and mitoKATP channel current has significantly increased (P<0.05).

CONCLUSIONCurcumin can inhibit &alpha;-synuclein gene overexpression or mutation induced &alpha;-synuclein oligomers formation. It may block apoptosis induced by wild-type overexpression or mutation of &alpha;-synuclein. By stabilizing mitochondrial membrane potential. Opening of mitoKATP channel may have been the initiating protective mechanism of apoptosis induced by wild-type overexpression or mutation of &alpha;-synuclein. Curcumin may antagonize above cytotoxicity through further opening the mitoKATP channel.

Animals ; Apoptosis ; drug effects ; Cell Line ; Curcumin ; pharmacology ; Humans ; KATP Channels ; chemistry ; genetics ; metabolism ; Mitochondria ; drug effects ; genetics ; metabolism ; Mutation ; drug effects ; PC12 Cells ; Parkinson Disease ; drug therapy ; genetics ; metabolism ; physiopathology ; Rats ; alpha-Synuclein ; genetics

Mammalian cells remove misfolded proteins using various proteolytic systems, including the ubiquitin (Ub)-proteasome system (UPS), chaperone mediated autophagy (CMA) and macroautophagy. The majority of misfolded proteins are degraded by the UPS, in which Ub-conjugated substrates are deubiquitinated, unfolded and cleaved into small peptides when passing through the narrow chamber of the proteasome. The substrates that expose a specific degradation signal, the KFERQ sequence motif, can be delivered to and degraded in lysosomes via the CMA. Aggregation-prone substrates resistant to both the UPS and the CMA can be degraded by macroautophagy, in which cargoes are segregated into autophagosomes before degradation by lysosomal hydrolases. Although most misfolded and aggregated proteins in the human proteome can be degraded by cellular protein quality control, some native and mutant proteins prone to aggregation into beta-sheet-enriched oligomers are resistant to all known proteolytic pathways and can thus grow into inclusion bodies or extracellular plaques. The accumulation of protease-resistant misfolded and aggregated proteins is a common mechanism underlying protein misfolding disorders, including neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), prion diseases and Amyotrophic Lateral Sclerosis (ALS). In this review, we provide an overview of the proteolytic pathways in neurons, with an emphasis on the UPS, CMA and macroautophagy, and discuss the role of protein quality control in the degradation of pathogenic proteins in neurodegenerative diseases. Additionally, we examine existing putative therapeutic strategies to efficiently remove cytotoxic proteins from degenerating neurons.
Alzheimer Disease/drug therapy/metabolism ; Amyloid beta-Peptides/metabolism ; Amyotrophic Lateral Sclerosis/drug therapy/metabolism ; Animals ; Autophagy/drug effects ; DNA-Binding Proteins/metabolism ; Humans ; Huntington Disease/drug therapy/genetics/metabolism ; Lysosomes/metabolism ; Molecular Targeted Therapy ; Mutation ; Nerve Tissue Proteins/genetics/metabolism ; Neurodegenerative Diseases/drug therapy/*metabolism ; Parkinson Disease/drug therapy/metabolism ; PrPSc Proteins/metabolism ; Prion Diseases/drug therapy/metabolism ; Proteasome Endopeptidase Complex/metabolism ; Proteolysis ; Proteostasis Deficiencies/metabolism ; Superoxide Dismutase/metabolism ; Ubiquitin/metabolism ; alpha-Synuclein/metabolism ; tau Proteins/metabolism

Lysosomal dysfunction is a common pathological feature of neurodegenerative diseases. GTP-binding protein type A1 (GBA1) encodes beta-glucocerebrosidase 1 (GCase 1), a lysosomal hydrolase. Homozygous mutations in GBA1 cause Gaucher disease, the most common lysosomal storage disease, while heterozygous mutations are strong risk factors for Parkinson's disease. However, whether loss of GCase 1 activity is sufficient for lysosomal dysfunction has not been clearly determined. Here, we generated human neuroblastoma cell lines with nonsense mutations in the GBA1 gene using zinc-finger nucleases. Depending on the site of mutation, GCase 1 activity was lost or maintained. The cell line with GCase 1 deficiency showed indications of lysosomal dysfunction, such as accumulation of lysosomal substrates, reduced dextran degradation and accumulation of enlarged vacuolar structures. In contrast, the cell line with C-terminal truncation of GCase 1 but with intact GCase 1 activity showed normal lysosomal function. When alpha-synuclein was overexpressed, accumulation and secretion of insoluble aggregates increased in cells with GCase 1 deficiency but did not change in mutant cells with normal GCase 1 activity. These results demonstrate that loss of GCase 1 activity is sufficient to cause lysosomal dysfunction and accumulation of alpha-synuclein aggregates.
Cell Line ; Enzyme Activation/genetics ; Gene Knockout Techniques ; Gene Order ; Genetic Loci ; Glucosylceramidase/genetics/*metabolism ; Humans ; Lysosomes/*metabolism ; Mutation ; *Protein Aggregation, Pathological/genetics ; Protein Binding ; Zinc Fingers ; alpha-Synuclein/chemistry/*metabolism

Parkinson's disease (PD) is an age-related progressive neurodegenerative disease associated with selective loss of dopaminergic neurons. The characteristic hallmark of the disease is intracytoplasmic proteinacious inclusion bodies called Lewy bodies, primarily consisting of a presynaptic protein alpha-synuclein. Oxidative stress-mediated damage to macromolecules have been shown to occur frequently in PD. Oxidative damage to DNA in the form of oxidized guanine (8-oxodG) accumulates in both the mitochondrial and nuclear DNA of dopaminergic neurons of the substantia nigra in PD. 8-oxodG-mediated transcriptional mutagenesis has been shown to have the potential to alter phenotype of cells through production of mutant pool of proteins. This review comprehensively summarizes the role of oxidative stress-mediated damage incurred during neurodegeneration, and highlights the scope of transcriptional mutagenesis event in leading to alpha-synuclein aggregation as seen in PD.
Amino Acid Sequence ; Animals ; Deoxyguanosine/*analogs & derivatives/metabolism ; Humans ; Molecular Sequence Data ; Mutagenesis ; *Oxidative Stress ; Parkinson Disease/*genetics/metabolism/pathology ; Protein Aggregation, Pathological/*genetics/metabolism/pathology ; Substantia Nigra/metabolism/*pathology ; Transcription, Genetic ; alpha-Synuclein/chemistry/*genetics

Multiple system atrophy (MSA) is a rare, late-onset and fatal neurodegenerative disease including multisystem neurodegeneration and the formation of alpha-synuclein containing oligodendroglial cytoplasmic inclusions (GCIs), which present the hallmark of the disease. MSA is considered to be a sporadic disease; however certain genetic aspects have been studied during the last years in order to shed light on the largely unknown etiology and pathogenesis of the disease. Epidemiological studies focused on the possible impact of environmental factors on MSA disease development. This article gives an overview on the findings from genetic and epigenetic studies on MSA and discusses the role of genetic or epigenetic factors in disease pathogenesis.
alpha-Synuclein ; Epigenomics* ; Genetics ; Inclusion Bodies ; Multiple System Atrophy* ; Neurodegenerative Diseases

Chronic neuroinflammation is an integral pathological feature of major neurodegenerative diseases. The recruitment of microglia to affected brain regions and the activation of these cells are the major events leading to disease-associated neuroinflammation. In a previous study, we showed that neuron-released alpha-synuclein can activate microglia through activating the Toll-like receptor 2 (TLR2) pathway, resulting in proinflammatory responses. However, it is not clear whether other signaling pathways are involved in the migration and activation of microglia in response to neuron-released alpha-synuclein. In the current study, we demonstrated that TLR2 activation is not sufficient for all of the changes manifested by microglia in response to neuron-released alpha-synuclein. Specifically, the migration of and morphological changes in microglia, triggered by neuron-released alpha-synuclein, did not require the activation of TLR2, whereas increased proliferation and production of cytokines were strictly under the control of TLR2. Construction of a hypothetical signaling network using computational tools and experimental validation with various peptide inhibitors showed that beta1-integrin was necessary for both the morphological changes and the migration. However, neither proliferation nor cytokine production by microglia was dependent on the activation of beta1-integrin. These results suggest that beta1-integrin signaling is specifically responsible for the recruitment of microglia to the disease-affected brain regions, where neurons most likely release relatively high levels of alpha-synuclein.
Animals ; Antigens, CD29/genetics/*metabolism ; Cell Line, Tumor ; *Cell Movement ; Cells, Cultured ; Culture Media, Conditioned/*pharmacology ; Gene Regulatory Networks ; Humans ; Mice ; Mice, Inbred C57BL ; Microglia/drug effects/metabolism/*physiology ; Neurons/*metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Toll-Like Receptor 2/metabolism ; alpha-Synuclein/*pharmacology

Aged ; Cognition Disorders ; genetics ; F-Box Proteins ; genetics ; HSP40 Heat-Shock Proteins ; genetics ; Humans ; Male ; Monocytes ; metabolism ; Parkinson Disease ; genetics ; alpha-Synuclein ; genetics

OBJECTIVETo investigate the effect of small ubiquitin-like modifier (SUMO-1) modification on the formation of Lewy body like inclusions in cytoplasm and apoptosis of HEK293 cell induced by overexpression and mutation of alpha-synuclein.

METHODScDNA encoding the human alpha-synuclein without the stop codon was cloned into a pGEM T-easy vector. Restriction enzyme mapping and DNA sequencing were performed to analyze the plasmid, which was then subcloned into a pEGFP-N1 vector. The recombinant plasmid alpha-synuclein-pEGFP was transfected into HEK293 cells by lipofectamin method. Inclusions in the cultured cells were identified with HE staining. Apoptosis of the HEK293 cell was measured by Hoechst 33258 staining, MTT and Annexin V-PE flow cytometry.

RESULTSThe Lewy-body like inclusions were found in cytoplasm of cultured cells. Hoechst staining showed that the nuclei of cells were enlarged in the wild-type and A53T mutation groups 48 h after transfection, chromatin were accumulated and appeared spot-like. The nucleus stain was equitable in the K96R and K96R-A53T groups. MTT assay showed that the viability of cells transfected with empty plasmid was 96.2%, but it dropped to 53.4% and 56.1% in cells transfected with wild-type alpha-synuclein-pEGFP and A53T mutant group, respectively. The viability was 72.3% and 69.8% in cells transfected with K96R and K96R-A53T, respectively (P<0.05). Forty eight hours after transfection, the apoptosis rate was 3.9% in empty plasmid group, 32.2% and 34.1% in cells transfected with wild-type and mutant alpha-synuclein-pEGFP, 19.4% and 20.3% in the K96R and K96R-A53T transfected cells. There was significant difference between the two groups (P<0.05).

CONCLUSIONSUMO-1 modification did not have influence on the Lewy body-like inclusions formation in cytoplasm of HEK293 cell in vitro, but had a toxic effect which could increase the apoptosis induced by wild type overexpression and mutation of alpha-synuclein.

Apoptosis ; genetics ; Cytoplasm ; metabolism ; Gene Expression ; Gene Expression Regulation ; Genetic Vectors ; genetics ; HEK293 Cells ; Humans ; Lewy Bodies ; metabolism ; Mutation ; genetics ; Parkinson Disease ; genetics ; metabolism ; RNA, Messenger ; genetics ; SUMO-1 Protein ; genetics ; metabolism ; alpha-Synuclein ; genetics ; metabolism