Mutations in the Leucine-rich repeat kinase 2 (LRRK2 ) gene are the most prevalent cause of familial Parkinson’s disease (PD). The increase in LRRK2 kinase activity observed in the pathogenic G2019S mutation is important for PD development. Several studies have reported that increased LRRK2 kinase activity and treatment with LRRK2 kinase inhibitors decreased and increased ciliogenesis, respectively, in mouse embryonic fibroblasts (MEFs) and retinal pigment epithelium (RPE) cells. In contrast, treatment of SH-SY5Y dopaminergic neuronal cells with PD-causing chemicals increased ciliogenesis. Because these reports were somewhat contradictory, we tested the effect of LRRK2 kinase activity on ciliogenesis in neurons. In SH-SY5Y cells, LRRK2 inhibitor treatment slightly increased ciliogenesis, but serum starvation showed no increase. In rat primary neurons, LRRK2 inhibitor treatment repeatedly showed no significant change. Little difference was observed between primary cortical neurons prepared from wild-type (WT) and G2019S +/- mice. However, a significant increase in ciliogenesis was observed in G2019S +/- compared to WT human fibroblasts, and this pattern was maintained in neural stem cells (NSCs) differentiated from the induced pluripotent stem cells (iPSCs) prepared from the same WT/G2019S fibroblast pair. NSCs differentiated from G2019S and its gene-corrected WT counterpart iPSCs were also used to test ciliogenesis in an isogenic background. The results showed no significant difference between WT and G2019S regardless of kinase inhibitor treatment and B27-deprivation-mimicking serum starvation. These results suggest that LRRK2 kinase activity may be not a direct regulator of ciliogenesis and ciliogenesis varies depending upon the cell type or genetic background.

Mutations in the Leucine-rich repeat kinase 2 (LRRK2 ) gene are the most prevalent cause of familial Parkinson’s disease (PD). The increase in LRRK2 kinase activity observed in the pathogenic G2019S mutation is important for PD development. Several studies have reported that increased LRRK2 kinase activity and treatment with LRRK2 kinase inhibitors decreased and increased ciliogenesis, respectively, in mouse embryonic fibroblasts (MEFs) and retinal pigment epithelium (RPE) cells. In contrast, treatment of SH-SY5Y dopaminergic neuronal cells with PD-causing chemicals increased ciliogenesis. Because these reports were somewhat contradictory, we tested the effect of LRRK2 kinase activity on ciliogenesis in neurons. In SH-SY5Y cells, LRRK2 inhibitor treatment slightly increased ciliogenesis, but serum starvation showed no increase. In rat primary neurons, LRRK2 inhibitor treatment repeatedly showed no significant change. Little difference was observed between primary cortical neurons prepared from wild-type (WT) and G2019S +/- mice. However, a significant increase in ciliogenesis was observed in G2019S +/- compared to WT human fibroblasts, and this pattern was maintained in neural stem cells (NSCs) differentiated from the induced pluripotent stem cells (iPSCs) prepared from the same WT/G2019S fibroblast pair. NSCs differentiated from G2019S and its gene-corrected WT counterpart iPSCs were also used to test ciliogenesis in an isogenic background. The results showed no significant difference between WT and G2019S regardless of kinase inhibitor treatment and B27-deprivation-mimicking serum starvation. These results suggest that LRRK2 kinase activity may be not a direct regulator of ciliogenesis and ciliogenesis varies depending upon the cell type or genetic background.

Since the neuroprotective effects of coffee and tobacco on Parkinson’s disease have been reported more than 50 years ago, clinical studies using caffeine and nicotine that were presumed as effective components of coffee and tobacco, respectively, are being actively executed. However, most results failed to show significant differences between the tested and control groups, and some studies revealed contradictory results to the neuroprotection. The reason for this might be that the effective components are something other than nicotine or caffeine, and/or differences to design the clinical trials such as patients recruiting, prescribed amount and period, and analyzed criteria etc. The review summarizes recent results for effect of coffee, tobacco as well as alcohol, representatives of indulgent food, on Parkinson’s disease.

Since the neuroprotective effects of coffee and tobacco on Parkinson’s disease have been reported more than 50 years ago, clinical studies using caffeine and nicotine that were presumed as effective components of coffee and tobacco, respectively, are being actively executed. However, most results failed to show significant differences between the tested and control groups, and some studies revealed contradictory results to the neuroprotection. The reason for this might be that the effective components are something other than nicotine or caffeine, and/or differences to design the clinical trials such as patients recruiting, prescribed amount and period, and analyzed criteria etc. The review summarizes recent results for effect of coffee, tobacco as well as alcohol, representatives of indulgent food, on Parkinson’s disease.

Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common genetic cause of Parkinson's disease (PD). LRRK2 contains a functional kinase domain and G2019S, the most prevalent LRRK2 pathogenic mutation, increases its kinase activity. LRRK2 regulates mitochondria morphology and autophagy in neurons. LPS treatment increases LRRK2 protein level and mitochondrial fission in microglia, and down-regulation of LRRK2 expression or inhibition of its kinase activity attenuates microglia activation. Here, we evaluated the direct role of LRRK2 G2019S in mitochondrial dynamics in microglia. Initial observation of microglia in G2019S transgenic mice revealed a decrease in mitochondrial area and shortage of microglial processes compared with their littermates. Next, we elucidated the molecular mechanisms of these phenotypes. Treatment of BV2 cells and primary microglia with LPS enhanced mitochondrial fission and increased Drp1, a mitochondrial fission marker, as previously reported. Importantly, both phenotypes were rescued by treatment with GSK2578215A, a LRRK2 kinase inhibitor. Finally, the protein levels of CD68, an active microglia marker, Drp1 and TNF-α were significantly higher in brain lysates of G2019S transgenic mice compared with the levels in their littermates. Taken together, our data suggest that LRRK2 could promote microglial mitochondrial alteration via Drp1 in a kinase-dependent manner, resulting in stimulation of pro-inflammatory responses. This mechanism in microglia might be a potential target to develop PD therapy since neuroinflammation by active microglia is a major symptom of PD.
Animals ; Autophagy ; Brain ; Down-Regulation ; Mice ; Mice, Transgenic ; Microglia* ; Mitochondria ; Mitochondrial Dynamics* ; Neurons ; Parkinson Disease ; Phenotype ; Phosphotransferases*

Extracellular vesicles (EVs) are small membranous vesicles that are secreted by various types of cells into biofluid or culture medium. EVs contain deoxyribonucleic acids, messenger ribonucleic acids (RNAs), microRNAs, lipids, and proteins derived from its cells of origin and can transfer those molecules to other targeted cells. Therefore, EVs can play important roles in intercellular communication. The findings of recent studies suggest that EVs can be used to spread protein aggregates in various neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. In addition, it has been recognized that EVs can be used as a material for detecting biomarkers for such diseases or as a therapeutic tool.
Alzheimer Disease ; Biomarkers ; DNA ; MicroRNAs ; Neurodegenerative Diseases ; Parkinson Disease ; RNA

Parkinson's disease (PD) is the second most common neurodegenerative motor disorder, affecting approximately 1% of the population aged > or =60 years. Recent investigations have shown that in addition to motor symptoms such as bradykinesia, resting tremor, and gait instability, PD also causes non-motor symptoms such as insomnia, constipation, depression, and dementia. Most PD cases occurred sporadically, but 5-10% is inherited as familial PD, and several PD-causative genes have been identified and intensively studied. Autophagy is a self-degrading mechanism of balancing the energy source in response to nutrient shortage and various stresses, and is a tightly regulated and complicated process that generates double-membrane organelles. Autophagy failure has recently been observed in both animal PD models and human PD patients. The intention of this review is to introduce recent findings regarding the relationship between causative genetic mutations in PD and autophagy, from a clinical perspective.
Animals ; Autophagy* ; Constipation ; Dementia ; Depression ; Gait ; Humans ; Hypokinesia ; Intention ; Mitochondrial Degradation ; Organelles ; Parkinson Disease* ; Sleep Initiation and Maintenance Disorders ; Tremor

Leucine-rich repeat kinase 2 (LRRK2) is a gene that, upon mutation, causes autosomal-dominant familial Parkinson's disease (PD). Yeast two-hybrid screening revealed that Snapin, a SNAP-25 (synaptosomal-associated protein-25) interacting protein, interacts with LRRK2. An in vitro kinase assay exhibited that Snapin is phosphorylated by LRRK2. A glutathione-S-transferase (GST) pull-down assay showed that LRRK2 may interact with Snapin via its Ras-of-complex (ROC) and N-terminal domains, with no significant difference on interaction of Snapin with LRRK2 wild type (WT) or its pathogenic mutants. Further analysis by mutation study revealed that Threonine 117 of Snapin is one of the sites phosphorylated by LRRK2. Furthermore, a Snapin T117D phosphomimetic mutant decreased its interaction with SNAP-25 in the GST pull-down assay. SNAP-25 is a component of the SNARE (Soluble NSF Attachment protein REceptor) complex and is critical for the exocytosis of synaptic vesicles. Incubation of rat brain lysate with recombinant Snapin T117D, but not WT, protein caused decreased interaction of synaptotagmin with the SNARE complex based on a co-immunoprecipitation assay. We further found that LRRK2-dependent phosphorylation of Snapin in the hippocampal neurons resulted in a decrease in the number of readily releasable vesicles and the extent of exocytotic release. Combined, these data suggest that LRRK2 may regulate neurotransmitter release via control of Snapin function by inhibitory phosphorylation.
Amino Acid Sequence ; Animals ; Exocytosis ; Female ; HEK293 Cells ; Humans ; Mice ; Molecular Sequence Data ; Mutant Proteins/metabolism ; Phosphorylation ; Phosphothreonine/metabolism ; Protein Binding ; Protein Interaction Mapping ; Protein Structure, Tertiary ; Protein-Serine-Threonine Kinases/*metabolism ; Qa-SNARE Proteins/metabolism ; Rats ; Rats, Sprague-Dawley ; Synaptosomal-Associated Protein 25/*metabolism ; Synaptotagmins/metabolism ; Vesicle-Associated Membrane Protein 2/metabolism ; Vesicular Transport Proteins/chemistry/*metabolism

During recent years, there has been remarkable progress with respect to the identification of molecular mechanisms and underlying pathology of neurodegenerative dementias. The latest evidence indicates that a common cause and pathological mechanism of diverse neurodegenerative dementias can be found in the increased production, misfolding, aggregation, and accumulation of specific proteins such as beta-amyloid, tau protein, alpha-synuclein, prion protein, polyglutamine, transactive response DNA-binding protein (TARDBP or TDP-43), or fused in sarcoma (FUS). The conformational variants of these proteins range from small oligomers to the characteristic pathologic inclusions. However, it is noteworthy that a certain pathology can be a hallmark of a certain dementia, but there is a substantial overlap between different pathologies and different types of dementias. In this review, molecular mechanisms and pathologies of different neurodegenerative dementias will be summarized from the perspective of proteins rather than from the viewpoint of individual dementias. We will also review recent evidence surrounding these protein misfolding disorders, the role of toxic oligomers, cell-to-cell transmission, and the links between the misfolded proteins, along with the general therapeutic strategies for the protein misfolding disorders.
alpha-Synuclein ; Dementia ; Neurodegenerative Diseases ; Peptides ; Proteins ; Proteostasis Deficiencies ; Sarcoma ; tau Proteins

The majority of neurodegenerative dementias are thought to result primarily from the misfolding, aggregation and accumulation of proteins which interfere with protein homeostasis in the brain. Some of them are caused by the expansion of unstable nucleotide repeats, which include Huntington's disease as a prototype. Other neurodevelopmental or neurodegenerative disorders, such as fragile X syndrome, some spinocerebellar ataxias and myotonic dystrophies exhibit cognitive or behavioral deficits as parts of their clinical manifestations. Unstable repeat expansions include trinucleotide, tetranucleotide, and pentanucleotide. Recently hexanucleotide repeat expansion in frontotemporal dementia and amyotrophic lateral sclerosis was identified. The pathogenic mechanisms for these repeat disorders include either loss of protein function or gain of function at the protein or RNA levels. The aim of this article is to review proposed mechanisms by which unstable repeat expansions give rise to degeneration of brain with the hope of understanding the diseases and providing insights into the areas of therapeutic intervention. We will review these potential mechanisms in the context of fragile X syndrome, Huntington's disease, spinocerebellar ataxias, myotonic dystrophy, and frontotemporal dementia and amyotrophic lateral sclerosis. We will also discuss the potential targets for therapeutic intervention.
Amyotrophic Lateral Sclerosis ; Brain ; Dementia ; Fragile X Syndrome ; Frontotemporal Dementia ; Homeostasis ; Huntington Disease ; Myotonic Dystrophy ; Neurodegenerative Diseases ; Proteins ; RNA ; Spinocerebellar Ataxias