Parkinson's disease (PD) is a common neurodegenerative disorder associated with aging. Great progresses have been made toward understanding the pathogenesis over the past decades. It seems that both genetic factors and environmental factors contribute to PD, while the precise pathogenesis still remains unknown. Recently, increasing evidence has suggested that autophagy dysregulation is closely related to PD. Dysregulation of the autophagic pathways has been observed in the brains of PD patients or in animal models of PD, and a number of PD-associated proteins, such as a-synuclein, Parkin and PINK1, were found to involve in autophagy, suggesting a link between autophagy and pathogenesis of PD. In this review, we summarized the role of PD-associated proteins in autophagy pathways. In addition, we described the efficacy of autophagy-modulating compounds in PD models and discussed promising strategies for PD therapy.
Animals ; Autophagy ; Humans ; Parkinson Disease ; physiopathology ; Protein Kinases ; metabolism ; Ubiquitin-Protein Ligases ; metabolism ; alpha-Synuclein ; metabolism

The accumulation of pathological α-synuclein (α-syn) in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease (PD). Recently, the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution of α-syn in PD patients. Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells, which contributes to the clearance of α-syn. However, the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons, which promotes the spread of α-syn pathology. In this article, we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis, highlighting the relationships between glial responses and the spread of α-syn pathology.
Humans ; Parkinson Disease/pathology* ; alpha-Synuclein/metabolism* ; Dopaminergic Neurons/metabolism* ; Pars Compacta/metabolism*

No abstract available.
Adult ; Cornea/*metabolism ; Fluorescent Antibody Technique, Indirect ; Humans ; Microscopy, Fluorescence ; Middle Aged ; alpha-Synuclein/*metabolism

Parkinson's disease (PD), a progressive neurodegenerative disorder, is pathologically characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of deposits of aggregated α-synuclein in intracellular inclusions known as Lewy bodies (LB). A highly localized inflammatory response mediated by reactive microglia is prominent in PD brains, but the mechanisms underlying the microglial activation are poorly understood. Recently some lines of evidences have shown that monomeric, or aggregated α-synuclein can activate microglia, the toxic factors released from activated microglia may lead to the cell death of dopaminergic neurons. This review is to summarize the recent progress on the role of α-synuclein induced microglia activation on the PD pathogenesis and progression, and to discuss the possible mechanisms involved.
Humans ; Microglia ; pathology ; Parkinson Disease ; etiology ; metabolism ; pathology ; alpha-Synuclein ; chemistry ; metabolism ; physiology

Animals ; Dopamine ; metabolism ; Dopaminergic Neurons ; metabolism ; Humans ; Iron ; metabolism ; Oxidative Stress ; Parkinson Disease ; metabolism ; Pars Compacta ; metabolism ; alpha-Synuclein ; metabolism

Parkinson's disease is a multifactorial disorder with several genes linked to the familial types of the disease. ATP13A2 is one of those genes and encode for a transmembrane protein localized in lysosomes and late endosomes. Previous studies suggested the roles of this protein in lysosomal functions and cellular ion homeostasis. Here, we set out to investigate the role of ATP13A2 in lysosomal function and in metabolism of alpha-synuclein, another PD-linked protein whose accumulation is implicated in the pathogenesis. We generated non-sense mutations in both copies of ATP13A2 gene in SH-SY5Y human neuroblastoma cells. We examined lysosomal function of ATP13A2-/- cells by measuring the accumulation of lysosomal substrate proteins, such as p62 and polyubiquitinated proteins, induction of acidic compartments, and degradation of ectopically introduced dextran. None of these measures were altered by ATP13A2 deficiency. The steady-state levels of alpha-synuclein in cells or secretion of this protein were unaltered either in ATP13A2-/- compared to the normal cells. Therefore, the proposed roles of ATP13A2 in lysosomal functions may not be generalized and may depend on the cellular context. The ATP13A2-/- cells generated in the current study may provide a useful control for studies on the roles of PD genes in lysosomal functions.
alpha-Synuclein* ; Dextrans ; Endosomes ; Homeostasis ; Humans ; Lysosomes ; Metabolism* ; Neuroblastoma ; Parkinson Disease ; Polyubiquitin

Parkinson's disease (PD), one of the most frequent neurodegenerative disorders, is characterized by the selective loss of dopaminergic neurons in the substantia nigra (SN). Genetic vulnerability, aging, environmental insults are believed to contribute to the pathogenesis of PD. However, the cellular and molecular mechanism of dopaminergic neurons degeneration remains incompletely understood. Dopamine (DA) metabolism is a cardinal physiological process in dopaminergic neurons, which is closely related to the loss of dopaminergic neurons in the SN. DA metabolism takes part in several pathological processes of PD neurodegeneration, such as iron metabolism disturbance, α-synuclein mis-folding, endoplasmic reticulum stress, protein degradation dysfunction, neuroinflammatory response, etc. In this review, we will describe altered DA metabolism and its contributions to PD pathogenesis.
Dopamine ; Dopaminergic Neurons ; Humans ; Parkinson Disease/etiology* ; Substantia Nigra ; alpha-Synuclein/metabolism*

OBJECTIVETo investigate the effect of sumoylation of alpha-synuclein by SUMO-1 on the mitochondria subcellular localization of alpha-synuclein and its degradation via ubiquitin-proteasome system.

METHODSPrimers of wild-type, A53T pathogenic mutant and K96R mutant of human alpha-synuclein were designed to amplify the corresponding cDNAs without stop codon. The cDNAs were cloned into pGEM T-easy vector, analyzed by using enzyme mapping and DNA sequencing, and subcloned into pEGFP-N1 vector. The recombinant plasmids of pEGFP-alpha-synuclein-WT, pEGFP-alpha-synuclein-A53T and pEGFP-alpha-synuclein-K96R were transfected into HEK293 cells by lipofectamine method. The expression of the alpha-synuclein protein was measured by immunofluorescence and confocal microscope. Then mitochondria staining as well as immunofluorescence were utilized to investigate the effect of wild-type, A53T mutant and sumoylation of alpha-synuclein on mitochondria subcellular localization of alpha-synuclein. The effect of sumoylation of alpha-synuclein on its degradation via the ubiquitin-proteasome system in the cells was assayed by Western-blot.

RESULTSThe enzyme mapping suggested that the eukaryotic expression plasmids for human wild-type, A53T and K96R mutants of the alpha-synuclein gene were constructed successfully. By immunofluorescence and confocal microscope, it was observed that alpha-synuclein-WT and alpha-synuclein-A53T proteins aggregated in cytoplasm, and alpha-synuclein-K96R protein aggregation was decreased in cytoplasm of cultured cells. The alpha-synuclein proteins of wild-type, A53T and K96R mutants were co-localized with mitochondria. Western-blot analysis revealed that both wild-type and A53T mutant affected the amount of the ubiquitinated proteins.

CONCLUSIONNeither overexpression of wild-type and A53T pathogenic mutant alpha-synuclein, nor sumoylation of alpha-synuclein, affected the subcellular localization in the mitochondria. However, overexpression of wild-type and A53T mutant alpha-synuclein affected the amount of the ubiquitinated proteins.

Blotting, Western ; Cell Line ; Humans ; Mitochondria ; metabolism ; Proteasome Endopeptidase Complex ; metabolism ; SUMO-1 Protein ; metabolism ; Ubiquitin ; metabolism ; alpha-Synuclein ; metabolism

OBJECTIVETo investigate over-expression of wild-type alpha-synuclein inducing the aberrant aggregation of alpha-synuclein in HEK293 cell in vitro.

METHODSThe cDNA encoding the human alpha-synuclein without the stop code was cloned into PGEM T-easy vector. Using enzyme map and DNA sequencing analyzed and determined the recombinant plasmid, and then sub-clone the alpha-synuclein cDNA fragment into pEGFP-N1 vector. The recombinant plasmids alpha-synuclein-pEGFP were transfected into HEK293 cells by lipofectamin 2000. The aberrant aggregation of alpha-synuclein was measured by EGFP fluorescence, anti-alpha-synuclein immunocytochemistry. The inclusions in the cultured cells were identified with HE staining.

RESULTSThe restriction enzyme map suggested that eukaryotic expression vector for human wild-type alpha-synuclein gene was constructed successfully. By EGFP fluorescence, anti-alpha-synuclein immunocytochemistry, it could be observed that the alpha-synuclein protein could aggregate in cytoplasm and the Lewy body-like inclusions found in cytoplasm of cultured cells.

CONCLUSIONThe over-expression of wild-type alpha-synuclein can induce protein aberrant aggregation and Lewy body-like inclusions formation in cytoplasm of HEK293 cell in vitro.

Cells, Cultured ; Gene Expression ; Humans ; Immunohistochemistry ; Inclusion Bodies ; metabolism ; Lewy Bodies ; metabolism ; Parkinson Disease ; genetics ; metabolism ; alpha-Synuclein ; genetics ; metabolism

OBJECTIVE: To investigate the effect of curcumin on dopamine neurons in Parkinson's disease (PD) and its mechanism. METHODS: SH-SY5Y human neuroblastoma cells were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish the PD cell model. The model cells were treated with curcumin and/or autophagy inhibitor 3-MA. After 48 h of drug treatment, the number of surviving dopamine neurons was detected by tyrosine hydroxylase immunofluorescence method. Western blotting was used to detect protein expression of α-Synuclein (α-Syn), transcription factor EB (TFEB) and autophagy-related proteins lysosome-associated membrane protein 2A (LAMP2A) and microtubule-associated protein 1 light chain 3-Ⅱ(LC3-Ⅱ); RT-PCR was used to detect mRNA expression of α-Syn. RESULTS: Compared with MPTP model group, curcumin increased the number of surviving dopamine neurons(<0.01), decreased both protein expression and mRNA expression of α-Syn (all <0.01), and increased protein expression of TFEB, LAMP2A and LC3-Ⅱ (all <0.01). When curcumin and 3-MA were given concurrently, the number of surviving dopamine neurons, protein expression of TFEB, LAMP2A and LC3-Ⅱ increased (<0.05 or <0.01), and both protein expression and mRNA expression of α-Syn decreased (<0.05 or <0.01) compared with MPTP model group; but the number of surviving dopamine neurons and protein expression of LAMP2A and LC3-Ⅱ decreased compared with curcumin group (all <0.05). CONCLUSIONS Curcumin exerts protective effect on dopamine neurons in PD, which may be associated with enhancing autophagy and promoting the clearance of α-Syn.
Animals ; Cell Line ; Curcumin ; pharmacology ; Dopaminergic Neurons ; drug effects ; Humans ; Mice ; Mice, Inbred C57BL ; Parkinson Disease ; alpha-Synuclein ; metabolism