Biology subjects

Tsou, W.-L.

Publications and source records attributed to Tsou, W.-L..

6 recordsLinked to original sources

bioRxiv2026

Chronic alpha-Synuclein Over-Expression and Ceruloplasmin Challenge Promote Distinct Iron and Redox Responses in M17 Cells

BackgroundWhile -synuclein (-syn) accumulation and iron dysregulation are hallmarks of Parkinsons Disease, the adaptations that enable neuronal survival under chronic protein stress remain unclear. Here, we investigated how -syn overexpression and ceruloplasmin (Cp)-mediated iron modulation alters iron and redox homeostasis. MethodsWe utilized human BE(2)-M17 neuroblastoma cell lines stably expressing different levels of -syn to examine the interplay between -syn, Ceruloplasmin (Cp)-mediated iron modulation, and the cellular response to oxidative stress. Analyses included Western blotting, immunofluorescence staining, soluble/insoluble fractionation, glutathione, reactive oxygen species (ROS) and hydrogen peroxide (H2O2) quantification, lipid peroxidation, ferrous iron, and cell viability. ResultsOur data suggest an unexpected relationship between chronic -syn expression and cellular redox regulation. Despite carrying a greater -syn burden, cells with higher -syn expression exhibit lower basal ROS, H2O2, and lipid peroxidation compared to control cells. These changes are not accompanied by activation of canonical antioxidant pathways suggesting that the reduced oxidative profile arises through alternative mechanisms. Besides, -syn over-expressing cells display significant remodeling of iron-handling pathways, including altered expression of ferritin heavy chain, transferrin receptor, and ferroportin, suggesting that chronically high -syn levels are associated with changes in iron homeostasis. In addition, this phenotype is not maintained following Cp overexpression. Although Cp reduces Fe{superscript 2} levels, it also induces substantial increases in ROS and H2O2 without corresponding changes in GPX4, glutathione, or related antioxidant systems. Thus, the reduced basal oxidative profile observed in -syn-over-expressing cells does not reflect enhanced canonical antioxidant capacity. Instead, chronically high -syn levels appear to be associated with adaptive remodeling of iron and redox pathways that become sensitive to oxidative imbalance. ConclusionChronic -syn over-expression promotes adaptive remodeling of iron and redox homeostasis, associated with reduced basal oxidative stress but increased sensitivity to Cp-mediated perturbation. These data link -syn burden to iron metabolism and stress-dependent vulnerability in synucleinopathies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/732494v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@9ab785org.highwire.dtl.DTLVardef@186a200org.highwire.dtl.DTLVardef@1f5c13forg.highwire.dtl.DTLVardef@162249e_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Bidirectional Crosstalk Between the SAGA Complex Deubiquitinase Module and the Molecular Circadian Clock

The Spt-Ada-Gcn5-acetyltransferase (SAGA) complex is a highly conserved chromatin-modifying transcriptional coactivator that regulates gene expression through both transcriptional and post-translational mechanisms. In addition to histone acetyltransferase activity, SAGA harbors a deubiquitinase module (DUBm) that influences protein stability, localization, and function by removal of ubiquitin. Although SAGAs roles in transcription are well characterized, how its enzymatic modules are dynamically regulated to coordinate its divergent activities remains less known. Here, we identify a bidirectional relationship between the molecular circadian clock and the SAGA DUBm. Our results indicate that circadian rhythms influence DUBm activities and expression, while the DUBm in turn shapes the timing and stability of core clock proteins and transcripts, positioning the DUBm as an important mediator of the molecular circadian clock.

neuroscience↗

bioRxiv2025

Regulation of polyamine interconversion enzymes affects α-Synuclein levels and toxicity in a Drosophila model of Parkinsons disease

Parkinson's Disease (PD) is a prevalent neurodegenerative disorder with the accumulation and aggregation of alpha-synuclein (&[alpha]-Syn) as a central pathological hallmark. Misfolding and aggregation of &[alpha]-Syn disrupts cellular homeostasis, hinders mitochondrial function, and activates neuroinflammatory responses, ultimately resulting in neuronal death. Recent biomarker research indicated a notable increase in the serum concentrations of three L-ornithine-derived polyamines (PAs): putrescine, spermidine, and spermine, each correlating with the progression of PD and its clinical subtypes. However, the role of PA pathways in PD pathology is poorly understood; it is unclear whether elevated PA concentrations are linked to PD pathology or whether they represent a secondary effect. In this study, we targeted PAs through RNAi knockdown of different PA-interconversion enzymes (PAIE) in a Drosophila melanogaster model of PD that overexpresses human, wild-type &[alpha]-Syn. Our findings reveal a significant impact on both the lifespan and motility of PD-model flies when crucial PAIE, such as ornithine decarboxylase 1 (ODC1), spermidine synthase (SRM), spermidine/spermine N1-acetyltransferase 1 (SAT1), and spermine oxidase (SMOX), are targeted. The overexpression of SAT1 and SMOX in this PD model had positive, enduring effects on fly lifespan. Additionally, we noted significant alterations in &[alpha]-Syn protein levels when PAIE are either knocked down or overexpressed. These findings underscore the role of PA pathways in PD and their potential targeting to modulate &[alpha]-Syn levels and mitigate neurodegeneration in PD.

neuroscience↗

bioRxiv2024

Insights into Dentatorubral-Pallidoluysian Atrophy from a new Drosophila model of disease

Dentatorubral-pallidoluysian atrophy (DRPLA) is a neurodegenerative disorder that presents with ataxia, dementia and epilepsy. As a member of the polyglutamine family of diseases, DRPLA is caused by abnormal CAG triplet expansion beyond 48 repeats in the protein-coding region of ATROPHIN 1 (ATN1), a transcriptional co-repressor. To better understand DRPLA, we generated new Drosophila lines that express full-length, human ATN1 with a normal (Q7) or pathogenic (Q88) repeat. Expression of ATN1 is toxic, with the polyglutamine-expanded version being consistently more problematic than wild-type ATN1. Fly motility, longevity and internal structures are negatively impacted by pathogenic ATN1. RNA-seq identified altered protein quality control and immune pathways in the presence of pathogenic ATN1. Based on these data, we conducted genetic experiments that confirmed the role of protein quality control components that ameliorate or exacerbate ATN1 toxicity. Hsc70-3, a chaperone, arose as a likely suppressor of toxicity. VCP (a proteasome-related AAA ATPase), Rpn11 (a proteasome-related deubiquitinase) and select DnaJ proteins (co-chaperones) were inconsistently protective, depending on the tissues where they were expressed. Lastly, informed by RNA-seq data that exercise-related genes may also be involved in this model of DRPLA, we conducted short-term exercise, which improved overall fly motility. This new model of DRPLA will prove important to understanding this understudied disease and will help to identify therapeutic targets for it.

neuroscience↗

bioRxiv2023

Progressive degeneration in a new Drosophila model of Spinocerebellar Ataxia type 7

Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of polyglutamine (polyQ) in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.

neuroscience↗

bioRxiv2023

Lysine 117 on ataxin-3 modulates toxicity in Drosophila models of Spinocerebellar Ataxia Type 3

Ataxin-3 (Atxn3) is a deubiquitinase with a polyglutamine (polyQ) repeat tract whose abnormal expansion causes the neurodegenerative disease, Spinocerebellar Ataxia Type 3 (SCA3; also known as Machado-Joseph Disease). The ubiquitin chain cleavage properties of Atxn3 are enhanced when it is ubiquitinated at lysine (K) at position 117. K117-ubiqutinated Atxn3 cleaves poly-ubiquitin more rapidly in vitro compared to its unmodified counterpart and this residue is also important for Atxn3 roles in cell culture and in Drosophila melanogaster. How polyQ expansion causes SCA3 remains unclear. To gather insight into the biology of disease of SCA3, here we posited the question: is K117 important for toxicity caused by Atxn3? We generated transgenic Drosophila lines that express full-length, human, pathogenic Atxn3 with 80 polyQ with an intact or mutated K117. We found that K117 mutation mildly enhances the toxicity and aggregation of pathogenic Atxn3 in Drosophila. An additional transgenic line that expresses Atxn3 without any K residues confirms increased aggregation of pathogenic Atxn3 whose ubiquitination is perturbed. These findings suggest Atxn3 ubiquitination as a regulatory step of SCA3, in part by modulating its aggregation.

neuroscience↗