Biology subjects

Tan, E.-K.

Publications and source records attributed to Tan, E.-K..

3 recordsLinked to original sources

bioRxiv2026

Dysregulation of miR-103a-3p/AGFG1 axis links endocytic trafficking dysfunction to ER stress in Parkinson's disease

Background: Parkinson's disease is defined by progressive dopaminergic neurodegeneration and -synuclein pathology. Endoplasmic reticulum (ER) stress and clathrin-mediated endocytosis dysfunction are implicated in disease pathogenesis, but the molecular mechanisms connecting these processes remain poorly understood. Here, we investigate a miR-103a-3p/AGFG1 axis as a regulator link between endocytic trafficking and ER stress in Parkinson's disease. Methods: MiR-103a-3p and AGFG1 were examined in plasma and postmortem substantia nigra from patients with Parkinson's disease and controls. Gain- and loss-of-function studies, target validation and live-cell imaging were used to define the role of the miR-103a-3p/AGFG1 axis in ER stress and endocytic trafficking. The pathway was further investigated in SNCA A53T and LRRK2 G2019S hiPSC-derived neurons. Therapeutic targeting of AGFG1 was evaluated using antisense oligonucleotides (ASOs) in vitro and in a 6-hydroxydopamine mouse model. Results: MiR-103a-3p was significantly reduced in Parkinson's disease plasma and substantia nigra, whereas AGFG1 was increased in nigral tissue. MiR-103a-3p directly repressed AGFG1 and attenuated thapsigargin-induced ER stress, while miR-103a-3p inhibition or AGFG1 overexpression exacerbated stress signalling. AGFG1 knockdown reversed the effects of miR-103a-3p inhibition, establishing AGFG1 as a functional downstream effector. Mechanistically, AGFG1 associated and co-trafficked with clathrin-positive vesicles, whereas ER stress progressively disrupted AGFG1-clathrin vesicle dynamics, revealing an association between endocytic trafficking and stress signalling. In genetic Parkinson's disease models, SNCA A53T and LRRK2 G2019S neurons showed mutation-dependent differences in AGFG1 expression and stress regulation. eIF2 phosphorylation increased in both SNCA A53T and LRRK2 G2019S neurons, whereas AGFG1 and GADD34 upregulation was selective to SNCA A53T neurons. Importantly, ASO-mediated AGFG1 suppression attenuated ER stress in vitro and preserved nigral dopaminergic neurons with improved motor performance in vivo. Conclusion: Our findings identify the miR-103a-3p/AGFG1 axis as a previously unrecognised molecular link between endocytic trafficking dysfunction and ER stress in Parkinson's disease, and support AGFG1 as a mechanistically potential therapeutic target.

neuroscience↗

bioRxiv2018

Automated leg tracking reveals distinct conserved gait and tremor signatures in Drosophila models of Parkinson’s Disease and Spinocerebellar ataxia 3

Genetic models in Drosophila have made invaluable contributions to our understanding of the molecular mechanisms underlying neurodegeneration. In human patients, some neurodegenerative diseases lead to characteristic movement dysfunctions, such as abnormal gait and tremors. However, it is currently unknown whether similar movement defects occur in the respective fly models, which could be used to model and better understand the pathophysiology of movement disorders. To address this question, we developed a machine-learning image-analysis programme -- Feature Learning-based LImb segmentation and Tracking (FLLIT) -- that automatically tracks leg claw positions of freely moving flies recorded on high-speed video, generating a series of body and leg movement parameters. Of note, FLLIT requires no user input for learning. We used FLLIT to characterise fly models of Parkinsons Disease (PD) and Spinocerebellar ataxia 3 (SCA3). Between these models, walking gait and tremor characteristics differed markedly, and recapitulated signatures of the respective human diseases. Selective expression of mutant SCA3 in dopaminergic neurons led to phenotypes resembling that of PD flies, suggesting that the behavioural phenotype may depend on the circuits affected, rather than the specific nature of the mutation. Different mutations produced tremors in distinct leg pairs, indicating that different motor circuits are affected. Almost 190,000 video frames were tracked in this study, allowing, for the first time, high-throughput analysis of gait and tremor features in Drosophila mutants. As an efficient assay of mutant gait and tremor features in an important model system, FLLIT will enable the analysis of the neurogenetic mechanisms that underlie movement disorders.

neuroscience↗

bioRxiv2018

Large-scale whole-genome sequencing of three diverse Asian populations in Singapore

Asian populations are currently underrepresented in human genetics research. Here we present whole-genome sequencing data of 4,810 Singaporeans from three diverse ethnic groups: 2,780 Chinese, 903 Malays, and 1,127 Indians. Despite a medium depth of 13.7x, we achieved essentially perfect (>99.8%) sensitivity and accuracy for detecting common variants and good sensitivity (>89%) for detecting extremely rare variants with <0.1% allele frequency. We found 89.2 million single-nucleotide polymorphisms (SNPs) and 9.1 million small insertions and deletions (INDELs), more than half of which have not been cataloged in dbSNP. In particular, we found 126 common deleterious mutations (MAF>0.01) that were absent in the existing public databases, highlighting the importance of local population reference for genetic diagnosis. We describe fine-scale genetic structure of Singapore populations and their relationship to worldwide populations from the 1000 Genomes Project. In addition to revealing noticeable amounts of admixture among three Singapore populations and a Malay-related novel ancestry component that has not been captured by the 1000 Genomes Project, our analysis also identified some fine-scale features of genetic structure consistent with two waves of prehistoric migration from south China to Southeast Asia. Finally, we demonstrate that our data can substantially improve genotype imputation not only for Singapore populations, but also for populations across Asia and Oceania. These results highlight the genetic diversity in Singapore and the potential impacts of our data as a resource to empower human genetics discovery in a broad geographic region.

genetics↗