Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Mutations in the SNCA gene, which encodes α-synuclein (α-syn), play a key role in the development of genetic Parkinson's disease (PD). α-Syn is a major component of Lewy bodies in PD and glial cytoplasmic inclusions in multiple system atrophy (MSA). Rapid eye movement sleep behavior disorder (RBD) patients often progress to PD, dementia with Lewy bodies (DLB), or MSA, collectively known as α-synucleinopathies. The loss of dopaminergic neurons with Lewy bodies precedes motor dysfunction in these diseases, but the mechanisms of neurodegeneration due to α-syn aggregation are poorly understood. Monitoring α-syn aggregation in vivo could serve as a diagnostic biomarker and help elucidate the pathogenesis, necessitating a simple and accurate detection method. Seed amplification assays (SAAs), such as real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA), are used to detect small amounts of abnormally structured α-syn protofibrils, which are central to aggregation. These methods are promising for the early diagnosis of α-synucleinopathy. Differences in α-syn filament structures between α-synucleinopathies, observed through transmission electron microscopy and cryo-electron microscopy, suggest their role in the pathogenesis of neurodegeneration. SAAs may differentiate between subtypes of α-synucleinopathy and other diseases. Efforts are also being made to identify α-syn from blood using various methods. This review introduces body fluid α-syn biomarkers based on pathogenic α-syn seeds, which are expected to redefine α-synucleinopathy diagnosis and staging, improving clinical research accuracy and facilitating biomarker development.

DOI： 10.14802/jmd.24075

PubMed

<p>Single-molecule imaging in living cells is an effective tool for elucidating the mechanisms of cellular phenomena at the molecular level. However, the analysis was not designed for throughput and requires high expertise, preventing it from reaching large scale, which is necessary when searching for rare cells that induce singularity phenomena. To overcome this limitation, we have automated the imaging procedures by combining our own focusing device, artificial intelligence, and robotics. The apparatus, called automated in-cell single-molecule imaging system (AiSIS), achieves a throughput that is a hundred-fold higher than conventional manual imaging operations, enabling the analysis of molecular events by individual cells across a large population. Here, using AiSIS, we demonstrate the single-molecule imaging of molecular behaviors and reactions related to tau protein aggregation, which is considered a singularity phenomenon in neurological disorders. Changes in the dynamics and kinetics of molecular events were observed inside and on the basal membrane of cells after the induction of aggregation. Additionally, to detect rare cells based on the molecular behavior, we developed a method to identify the state of individual cells defined by the quantitative distribution of molecular mobility and clustering. Using this method, cellular variations in receptor behavior were shown to decrease following ligand stimulation. This cell state analysis based on large-scale single-molecule imaging by AiSIS will advance the study of molecular mechanisms causing singularity phenomena.</p>

DOI： 10.2142/biophysico.bppb-v21.s018

Publishing type：Research paper (scientific journal)  

DOI： 10.2142/biophysico.bppb-v21.s008

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The ubiquitin‒proteasome system (UPS) and autophagy are the two primary cellular pathways of misfolded or damaged protein degradation that maintain cellular proteostasis. When the proteasome is dysfunctional, cells compensate for impaired protein clearance by activating aggrephagy, a type of selective autophagy, to eliminate ubiquitinated protein aggregates; however, the molecular mechanisms by which impaired proteasome function activates aggrephagy remain poorly understood. Here, we demonstrate that activation of aggrephagy is transcriptionally induced by the transcription factor NRF1 (NFE2L1) in response to proteasome dysfunction. Although NRF1 has been previously shown to induce the expression of proteasome genes after proteasome inhibition (i.e., the proteasome bounce-back response), our genome-wide transcriptome analyses identified autophagy-related p62/SQSTM1 and GABARAPL1 as genes directly targeted by NRF1. Intriguingly, NRF1 was also found to be indispensable for the formation of p62-positive puncta and their colocalization with ULK1 and TBK1, which play roles in p62 activation via phosphorylation. Consistently, NRF1 knockdown substantially reduced the phosphorylation rate of Ser403 in p62. Finally, NRF1 selectively upregulated the expression of GABARAPL1, an ATG8 family gene, to induce the clearance of ubiquitinated proteins. Our findings highlight the discovery of an activation mechanism underlying NRF1-mediated aggrephagy through gene regulation when proteasome activity is impaired.

DOI： 10.1038/s41598-023-41492-9

PubMed

CiNii Books

Abnormal α-synuclein aggregation is a key pathological feature of a group of neurodegenerative diseases known as synucleinopathies, which include Parkinson's disease (PD), dementia with Lewy bodies and multiple system atrophy (MSA). The pathogenic β-sheet seed conformation of α-synuclein is found in various tissues, suggesting potential as a biomarker, but few studies have been able to reliably detect these seeds in serum samples. In this study, we developed a modified assay system, called immunoprecipitation-based real-time quaking-induced conversion (IP/RT-QuIC), which enables the detection of pathogenic α-synuclein seeds in the serum of individuals with synucleinopathies. In our internal first and second cohorts, IP/RT-QuIC showed high diagnostic performance for differentiating PD versus controls (area under the curve (AUC): 0.96 (95% confidence interval (CI) 0.95-0.99)/AUC: 0.93 (95% CI 0.84-1.00)) and MSA versus controls (AUC: 0.64 (95% CI 0.49-0.79)/AUC: 0.73 (95% CI 0.49-0.98)). IP/RT-QuIC also showed high diagnostic performance in differentiating individuals with PD (AUC: 0.86 (95% CI 0.74-0.99)) and MSA (AUC: 0.80 (95% CI 0.65-0.97)) from controls in a blinded external cohort. Notably, amplified seeds maintained disease-specific properties, allowing the differentiation of samples from individuals with PD versus MSA. In summary, here we present a novel platform that may allow the detection of individuals with synucleinopathies using serum samples.

DOI： 10.1038/s41591-023-02358-9

PubMed

J-GLOBAL

J-GLOBAL

Authorship：Lead author,　Last author,　Corresponding author   Publishing type：Article, review, commentary, editorial, etc. (other)  

property_type：Patent 

Application no：特願2023-030021 

property_type：Patent 

Application no：特願2021-000188 

Announcement no：特開2022-105412 

J-GLOBAL

property_type：Patent 

Application no：特願2021-000188