bims-proned 2025-02-23 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2025–02–23
twenty-two papers selected by
Verena Kohler, Umeå University

The roles of intrinsically disordered proteins in neurodegeneration.
A novel lncRNA FAM151B-DT regulates autophagy and degradation of aggregation prone proteins.
Cholesterol-mediated Lysosomal Dysfunction in APOE4 Astrocytes Promotes α-Synuclein Pathology in Human Brain Tissue.
Small heat shock protein HSPB8 interacts with a pre-fibrillar TDP43 low complexity domain species to delay fibril formation.
The effect of AKT inhibition in α-synuclein-dependent neurodegeneration.
Glycosphingolipids in neurodegeneration - Molecular mechanisms, cellular roles, and therapeutic perspectives.
Temperature-Dependent Aggregation of Tau Protein Is Attenuated by Native PLGA Nanoparticles Under in vitro Conditions.
Insight into the thermo-responsive phase behavior of the P1 domain of α-synuclein using atomistic simulations.
Structurally targeted mutagenesis identifies key residues supporting α-synuclein misfolding in multiple system atrophy.
Advances in Molecular Docking Techniques for Targeting Protein Misfolding in Neurodegenerative Diseases.
Guide to the structural characterization of protein aggregates and amyloid fibrils by CD spectroscopy.
Expression analysis of molecular chaperones associated with disaggregation complex in rotenone-induced Parkinsonian rat model.
Nemo-like kinase disrupts nuclear import and drives TDP43 mislocalization in ALS.
Chemical Synthesis Reveals Pathogenic Role of N-Glycosylation in Microtubule-Associated Protein Tau.
Neuronal FAM171A2 mediates α-synuclein fibril uptake and drives Parkinson's disease.
Polyamine biosynthesis dysregulation in Alzheimer's disease and Down syndrome cellular models.
Synergistic MAPT mutations as a platform to uncover modifiers of tau pathogenesis.
SUMO2/3 conjugation of TDP-43 protects against aggregation.
The cholesterol 24-hydroxylase CYP46A1 promotes α-synuclein pathology in Parkinson's disease.
Nuclear Import Defects Drive Cell Cycle Dysregulation in Neurodegeneration.
Glycated α-Synuclein Renders Glial Cell Activation and Induces Degeneration of Dopaminergic Neurons: A Potential Implication for the Development of Parkinson's Disease.
Outlook of SNCA (α-synuclein) transgenic fly models in delineating the sequel of mitochondrial dysfunction in Parkinson's disease.

Biochim Biophys Acta Gen Subj. 2025 Feb 13. pii: S0304-4165(25)00017-0. [Epub ahead of print]1869(4): 130772

The roles of intrinsically disordered proteins in neurodegeneration.

Kagistia Hana Utami, Satoru Morimoto, Yasue Mitsukura, Hideyuki Okano.

  Neurodegenerative diseases such as Amyotrophic Lateral Sclerosis, Alzheimer's disease, Parkinson's disease, and Huntington's disease share a common pathological hallmark: the accumulation of misfolded proteins, particularly involving intrinsically disordered proteins (IDPs) like TDP-43, FUS, Tau, α-synuclein, and Huntingtin. These proteins undergo pathological aggregation, forming toxic inclusions that disrupt cellular function. The dysregulation of proteostasis mechanisms, including the ubiquitin-proteasome system (UPS), ubiquitin-independent proteasome system (UIPS), autophagy, and molecular chaperones, exacerbates these proteinopathies by failing to clear misfolded proteins effectively. Emerging therapeutic strategies aim to restore proteostasis through proteasome activators, autophagy enhancers, and chaperone-based interventions to prevent the toxic accumulation of IDPs. Additionally, understanding liquid-liquid phase separation (LLPS) and its role in stress granule dynamics offers novel insights into how aberrant phase transitions contribute to neurodegeneration. By targeting the molecular pathways involved in IDP aggregation and proteostasis regulation, and better understanding the specificity of each component, research in this area will pave the way for innovative therapeutic approaches to combat these neurodegenerative diseases. This review discusses the molecular mechanisms underpinning IDP pathology, highlights recent advancements in drug discovery, and explores the potential of targeting proteostasis machinery to develop effective therapies.

Keywords:  Aggregation; Autophagy; Chaperone; Intrinsically disordered proteins; Liquid-liquid phase separation; Neurodegenerative diseases; Proteostasis

DOI:  https://doi.org/10.1016/j.bbagen.2025.130772
medRxiv. 2025 Jan 24. pii: 2025.01.22.25320997. [Epub ahead of print]

A novel lncRNA FAM151B-DT regulates autophagy and degradation of aggregation prone proteins.

Arun Renganathan, Miguel A Minaya, Matthew Broder, Isabel Alfradique-Dunham, Michelle Moritz, Reshma Bhagat, Jacob Marsh, Anthony Verbeck, Grant Galasso, Emma Starr, David A Agard, Carlos Cruchaga, Celeste M Karch.

Neurodegenerative diseases share common features of protein aggregation along with other pleiotropic traits, including shifts in transcriptional patterns, neuroinflammation, disruptions in synaptic signaling, mitochondrial dysfunction, oxidative stress, and impaired clearance mechanisms like autophagy. However, key regulators of these pleotropic traits have yet to be identified. Here, we discovered a novel long non-coding RNA (lncRNA), FAM151B-DT , that is reduced in a stem cell model of frontotemporal dementia with tau inclusions (FTLD-tau) and in brains from FTLD-tau, progressive supranuclear palsy, Alzheimer's disease, and Parkinson's disease patients. We show that silencing FAM151B-DT in vitro is sufficient to enhance tau aggregation. To begin to understand the mechanism by which FAM151B-DT mediates tau aggregation and contributes to several neurodegenerative diseases, we deeply characterized this novel lncRNA and found that FAM151B-DT resides in the cytoplasm where it interacts with tau, α-synuclein, HSC70, and other proteins enriched in protein homeostasis. When silenced, FAM151B-DT blocks autophagy, leading to the accumulation of tau and α-synuclein. Importantly, we discovered that increasing FAM151B-DT expression is sufficient to promote autophagic flux, reduce phospho-tau and α-synuclein, and reduce tau aggregation. Overall, these findings pave the way for further exploration of FAM151B-DT as a promising molecular target for several neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.01.22.25320997
bioRxiv. 2025 Feb 14. pii: 2025.02.09.637107. [Epub ahead of print]

Cholesterol-mediated Lysosomal Dysfunction in APOE4 Astrocytes Promotes α-Synuclein Pathology in Human Brain Tissue.

Louise A Mesentier-Louro, Camille Goldman, Alain Ndayisaba, Alice Buonfiglioli, Rikki B Rooklin, Braxton R Schuldt, Abigail Uchitelev, Vikram Khurana, Joel W Blanchard.

The pathological hallmark of neurodegenerative disease is the aberrant post-translational modification and aggregation of proteins leading to the formation of insoluble protein inclusions. Genetic factors like APOE4 are known to increase the prevalence and severity of tau, amyloid, and α-Synuclein inclusions. However, the human brain is largely inaccessible during this process, limiting our mechanistic understanding. Here, we developed an iPSC-based 3D model that integrates neurons, glia, myelin, and cerebrovascular cells into a functional human brain tissue (miBrain). Like the human brain, we found pathogenic phosphorylation and aggregation of α-Synuclein is increased in the APOE4 miBrain. Combinatorial experiments revealed that lipid-droplet formation in APOE4 astrocytes impairs the degradation of α-synuclein and leads to a pathogenic transformation that seeds neuronal inclusions of α-Synuclein. Collectively, this study establishes a robust model for investigating protein inclusions in human brain tissue and highlights the role of astrocytes and cholesterol in APOE4 -mediated pathologies, opening therapeutic opportunities.

DOI: https://doi.org/10.1101/2025.02.09.637107
bioRxiv. 2025 Jan 30. pii: 2025.01.28.635368. [Epub ahead of print]

Small heat shock protein HSPB8 interacts with a pre-fibrillar TDP43 low complexity domain species to delay fibril formation.

Khaled M Jami, Daniel C Farb, Kayla M Osumi, Catelynn C Shafer, Sophie Criscione, Dylan T Murray.

The loss of cellular proteostasis through aberrant stress granule formation is implicated in neurodegenerative diseases. Stress granules are formed by biomolecular condensation involving protein-protein and protein-RNA interactions. These assemblies are protective, but can rigidify, leading to amyloid-like fibril formation, a hallmark of the disease pathology. Key proteins dictating stress granule formation and disassembly, such as TDP43, contain low-complexity (LC) domains that drive fibril formation. HSPB8, a small heat shock protein, plays a critical role modulating stress granule fluidity, preventing aggregation and promoting degradation of misfolded proteins. We examined the interaction between HSPB8 and the TDP43 LC using thioflavin T (ThT) and fluorescence polarization (FP) aggregation assays, fluorescence microscopy and photobleaching experiments, and crosslinking mass spectrometry (XL-MS). Our results indicate that HSPB8 delays TDP43 LC aggregation through domain-specific interactions with fibril nucleating species, without affecting fibril elongation rates. These findings provide mechanistic insight into how ATP-independent chaperones mediate LC domain aggregation and provide a basis for investigating how the TDP43 LC subverts chaperone activity in neurodegenerative disease.
Significance Statement: ATP-independent chaperones facilitate clearance of aggregated proteins through autophagy. This study provides insight into the molecular mechanism by which small heat shock proteins interact with the aggregation-prone low complexity protein domains of RNA-binding proteins linked to neurodegenerative disease pathologies. The results provide a foundation for designing improved chaperones as therapeutics and illustrate a methodology to identify regions in low complexity domains for targeted drug development in the context of neurodegenerative disease.

DOI: https://doi.org/10.1101/2025.01.28.635368
Front Mol Neurosci. 2025 ;18 1524044

The effect of AKT inhibition in α-synuclein-dependent neurodegeneration.

Bedri Ranxhi, Zoya R Bangash, Zachary M Chbihi, Sokol V Todi, Peter A LeWitt, Wei-Ling Tsou.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of individuals worldwide. A hallmark of PD pathology is the accumulation of α-synuclein (α-Syn), a small protein known to support neuronal development and function. However, in PD, α-Syn cumulatively misfolds into toxic aggregates that disrupt cellular processes and contribute to neuronal damage and neurodegeneration. Previous studies implicated the AKT signaling pathway in α-Syn toxicity in cellular models of PD, suggesting AKT as a potential therapeutic target. Here, we investigated the effect of AKT inhibition in a Drosophila model of synucleinopathy. We observed that administration of the AKT inhibitor, A-443654 led to mild improvements in both survival and motor function in flies expressing human α-Syn. Genetic studies revealed that reduction of AKT levels decreased α-Syn protein levels, concomitant with improved physiological outcomes. The protective effects of AKT reduction appear to operate through the fly ortholog of NF-κB, Relish, suggesting a link between AKT and NF-κB in regulating α-Syn levels. These findings highlight the AKT cascade as a potential therapeutic target for synucleinopathies and provide insights into mechanisms that could be utilized to reduce α-Syn toxicity in PD and related disorders, such as multiple system atrophy.

Keywords:  AKT; NF-κB; Parkinson’s disease; neurodegenerative disease; protein misfolding disorders; proteinopathy; synucleinopathy; α-synuclein

DOI:  https://doi.org/10.3389/fnmol.2025.1524044
Neurobiol Dis. 2025 Feb 18. pii: S0969-9961(25)00067-1. [Epub ahead of print] 106851

Glycosphingolipids in neurodegeneration - Molecular mechanisms, cellular roles, and therapeutic perspectives.

Andreas J Hülsmeier.

  Neurodegenerative diseases, including Alzheimer's (AD), Parkinson's (PD), Huntington's (HD), and amyotrophic lateral sclerosis (ALS), are characterized by progressive neuronal loss and pose significant global health challenges. Glycosphingolipids (GSLs), critical components of neuronal membranes, regulate signal transduction, membrane organization, neuroinflammation, and lipid raft functionality. This review explores GSL roles in neural development, differentiation, and neurogenesis, along with their dysregulation in neurodegenerative diseases. Aberrations in GSL metabolism drive key pathological features such as protein aggregation, neuroinflammation, and impaired signaling. Specific GSLs, such as GM1, GD3, and GM3, influence amyloid-beta aggregation in AD, α-synuclein stability in PD, and mutant huntingtin toxicity in HD. Therapeutic strategies targeting GSL metabolism, such as GM1 supplementation and enzyme modulation, have demonstrated potential to mitigate disease progression. Further studies using advanced lipidomics and glycomics may support biomarker identification and therapeutic advancements. This work aims to highlight the translational potential of GSL research for diagnosing and managing devastating neurodegenerative conditions.

Keywords:  Cellular signaling; Gangliosides; Glycosphingolipids; Lipid rafts; Neurodgeneration

DOI:  https://doi.org/10.1016/j.nbd.2025.106851
Int J Nanomedicine. 2025 ;20 1999-2019

Temperature-Dependent Aggregation of Tau Protein Is Attenuated by Native PLGA Nanoparticles Under in vitro Conditions.

Pallabi Sil Paul, Mallesh Rathnam, Aria Khalili, Leonardo M Cortez, Mahalashmi Srinivasan, Emmanuel Planel, Jae-Young Cho, Holger Wille, Valerie L Sim, Sue-Ann Mok, Satyabrata Kar.

   Introduction: Hyperphosphorylation and aggregation of the microtubule-associated tau protein, which plays a critical role in many neurodegenerative diseases (ie, tauopathies) including Alzheimer's disease (AD), are known to be regulated by a variety of environmental factors including temperature. In this study we evaluated the effects of FDA-approved poly (D,L-lactide-co-glycolic) acid (PLGA) nanoparticles, which can inhibit amyloid-β aggregation/toxicity in cellular/animal models of AD, on temperature-dependent aggregation of 0N4R tau isoforms in vitro.
Methods: We have used a variety of biophysical (Thioflavin T kinetics, dynamic light scattering and asymmetric-flow field-flow fractionation), structural (fluorescence imaging and transmission electron microscopy) and biochemical (Filter-trap assay and detection of soluble protein) approaches, to evaluate the effects of native PLGA nanoparticles on the temperature-dependent tau aggregation.
Results: Our results show that the aggregation propensity of 0N4R tau increases significantly in a dose-dependent manner with a rise in temperature from 27°C to 40°C, as measured by lag time and aggregation rate. Additionally, the aggregation of 2N4R tau increases in a dose-dependent manner. Native PLGA significantly inhibits tau aggregation at all temperatures in a concentration-dependent manner, possibly by interacting with the aggregation-prone hydrophobic hexapeptide motifs of tau. Additionally, native PLGA is able to trigger disassembly of preformed 0N4R tau aggregates as a function of temperature from 27°C to 40°C.
Conclusion: These results, taken together, suggest that native PLGA nanoparticles can not only attenuate temperature-dependent tau aggregation but also promote disassembly of preformed aggregates, which increased with a rise of temperature. Given the evidence that temperature can influence tau pathology, we believe that native PLGA may have a unique potential to regulate tau abnormalities associated with AD-related pathology.

Keywords:  PLGA nanoparticles; protein aggregation; tau pathology; tau protein

DOI:  https://doi.org/10.2147/IJN.S494104
Phys Chem Chem Phys. 2025 Feb 21.

Insight into the thermo-responsive phase behavior of the P1 domain of α-synuclein using atomistic simulations.

Sanchari Chakraborty, Mithun Biswas.

Biomolecular condensate formation driven by intrinsically disordered proteins (IDPs) is regulated by interactions between various domains of the proteins. Such condensates are implicated in various neurodegenerative diseases. The presynaptic intrinsically disordered protein, α-Syn is involved in the pathogenesis of Parkinson's disease. The central non-amyloid β-component (NAC) domain in the protein is considered to be a major driver of pathogenic aggregation, although recent studies have suggested that the P1 domain from the flanking N-terminal region can act as a 'master controller' for α-Syn function and aggregation. To gain molecular insight into the phase behavior of the P1 domain itself, we investigate how assemblies of P1 (residues 36-42) chains phase separate with varying temperatures using all-atom molecular dynamics simulations. The simulations reveal that P1 is able to phase separate above a lower critical solution temperature. Formation of a condensed phase is driven by exclusion of water molecules by the hydrophobic chains. P1 chain density in the condensate is determined by weak multi-chain interactions between the residues. Moreover, tyrosine (Y39) is involved in the formation of strongest contacts between residue pairs in the dense phase. These results provide a detailed picture of condensate formation by a key segment of the α-Syn molecule.

DOI: https://doi.org/10.1039/d4cp04292a
J Parkinsons Dis. 2024 Nov;14(8): 1543-1558

Structurally targeted mutagenesis identifies key residues supporting α-synuclein misfolding in multiple system atrophy.

Patricia M Reis, Sara Am Holec, Chimere Ezeiruaku, Matthew P Frost, Christine K Brown, Samantha L Liu, Steven H Olson, Amanda L Woerman.

   BACKGROUND: Multiple system atrophy (MSA) and Parkinson's disease (PD) are caused by misfolded α-synuclein spreading throughout the central nervous system. While familial PD is linked to several α-synuclein mutations, no mutations are associated with MSA. We previously showed that the familial PD mutation E46K inhibits replication of MSA prions both in vitro and in vivo, providing key evidence to support the hypothesis that α-synuclein adopts unique strains in patients.
OBJECTIVE: Here we sought to further interrogate α-synuclein misfolding to identify the structural determinants that contribute to MSA strain biology.
METHODS: We engineered a panel of cell lines harbouring both PD-linked and novel mutations designed to identify key residues that facilitate α-synuclein misfolding in MSA. We also used Maestro in silico analyses to predict the effect of each mutation on α-synuclein misfolding into one of the reported MSA cryo-electron microscopy conformations.
RESULTS: In many cases, our modelling accurately identified mutations that facilitated or inhibited MSA replication. However, Maestro was occasionally unable to predict the effect of a mutation, demonstrating the challenge of using computational tools to investigate intrinsically disordered proteins. Finally, we used our cellular models to determine the mechanism underlying the E46K-driven inhibition of MSA replication, finding that the E46/K80 salt bridge is necessary to support α-synuclein misfolding.
CONCLUSIONS: Our studies used a structure-based approach to investigate α-synuclein misfolding, resulting in the creation of a powerful panel of cell lines that can be used to interrogate MSA strain biology.

Keywords:  Parkinson's disease; SNCA mutations; neurodegenerative disease; protein misfolding; α-synuclein strains

DOI:  https://doi.org/10.3233/JPD-240296
Curr Pharm Biotechnol. 2025 Feb 18.

Advances in Molecular Docking Techniques for Targeting Protein Misfolding in Neurodegenerative Diseases.

Kuldeep Singh, Jeetendra Kumar Gupta, Shiv Narayan, Ketki Rani, Divya Jain, Prateek Porwal, Mukesh Chandra Sharma, Shivendra Kumar.

  Neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Huntington's disease, represent a significant global health challenge with limited therapeutic options. Protein misfolding and aggregation, a common pathological hallmark in these disorders, have emerged as promising targets for therapeutic intervention. Molecular docking techniques have played a pivotal role in the identification and design of small molecules that can modulate protein misfolding, offering new hope for effective treatments. This review provides an overview of recent advancements in molecular docking techniques for targeting protein misfolding in neurodegenerative diseases. We discuss the principles and methodologies behind molecular docking, including various scoring functions and algorithms employed for accurate ligand-protein interactions. Additionally, we explore the use of molecular dynamics simulations and machine learning approaches to enhance the precision of docking studies. Furthermore, we highlight case studies and success stories where molecular docking has contributed to the discovery of potential drug candidates for neurodegenerative diseases. These include compounds that inhibit amyloid-β aggregation in Alzheimer's disease, α-synuclein oligomerisation in Parkinson's disease, and mutant huntingtin aggregation in Huntington's disease. We also discuss the problems and restrictions of molecular docking related to neurodegenerative diseases, such as how to accurately show the flexibility of proteins and why docking results need to be confirmed by experiments. We also discuss the structural biology methods, such as cryo-electron microscopy and X-ray crystallography, and how these techniques might help in improving molecular docking studies.

Keywords:  Molecular docking; drug design; neurodegenerative diseases; optimisation.; peptides; protein misfolding; small molecules; therapeutic strategies

DOI:  https://doi.org/10.2174/0113892010298545241108062449
Protein Sci. 2025 Mar;34(3): e70066

Guide to the structural characterization of protein aggregates and amyloid fibrils by CD spectroscopy.

József Kardos, Márton Péter Nyiri, Éva Moussong, Frank Wien, Tamás Molnár, Nikoletta Murvai, Vilmos Tóth, Henrietta Vadászi, Judit Kun, Frédéric Jamme, András Micsonai.

  Protein aggregation and amyloid formation are linked to numerous degenerative diseases, such as Alzheimer's or Parkinson's disease. Additionally, protein aggregation plays a crucial role in various biological processes, such as storage of molecules or cell signaling. Protein molecules can form a wide range of aggregates, from oligomers of different sizes to non-specific aggregates and highly ordered cross-β structured amyloid fibrils with diverse morphologies. Circular dichroism (CD) spectroscopy is a widely used technique to study protein structures providing detailed information at the secondary structure level, and is ideal to distinguish and characterize protein aggregates. Despite its potential, CD spectroscopy is often perceived as having limited application on protein aggregates due to challenges, such as sample inhomogeneity, precipitation, light scattering and other factors that complicate accurate analysis. In this study, we present a detailed protocol for examining the structure of protein aggregates and amyloid fibrils using CD spectroscopy. We outline the optimal experimental conditions for sample preparation and demonstrate how to identify and mitigate various interfering effects, using specific examples of disease-related amyloidogenic proteins. We also discuss the instrumental parameters, baseline subtraction, normalization, and quality control of CD spectra. Furthermore, we evaluate the performance of different secondary structure estimating algorithms on amyloid fibril CD spectra highlighting the superiority of BeStSel and CDNN. Our findings could enhance the structural analysis of protein aggregates, contributing to a better understanding of associated diseases and the development of new therapeutic strategies.

Keywords:  Alzheimer's disease; BeStSel; amyloid formation; amyloid‐β; circular dichroism spectroscopy; protein aggregation; secondary structure estimation

DOI:  https://doi.org/10.1002/pro.70066
Int J Biochem Cell Biol. 2025 Feb 12. pii: S1357-2725(25)00019-6. [Epub ahead of print]181 106752

Expression analysis of molecular chaperones associated with disaggregation complex in rotenone-induced Parkinsonian rat model.

Tanu, Minal Chaturvedi, Siraj Fatima, Smriti Singh Yadav, Prabeen Kumar Padhy, Saurabh Tiwari, Kavita Seth, Rajnish K Chaturvedi, Smriti Priya.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the aberrant aggregation and phosphorylation (ser129) of α-synuclein (α-syn, a presynaptic protein) which leads to the formation of pathogenic Lewy bodies. A critical factor in the pathogenesis of PD is the disruption of the cellular protein quality control system, where molecular chaperones and their co-chaperones are integral for mitigating proteotoxic stress. Although the role of molecular chaperones in PD and other protein aggregation diseases has been extensively investigated, the in vivo investigation of disaggregation chaperones, including HSP70, HSP105, and co-chaperone DNAJBs, remains relatively limited. The present study aims to elucidate the expression dynamics of the disaggregation molecular chaperones within the substantia nigra pars compacta of the rotenone-induced Parkinsonian rat model and its association with α-syn aggregation. The rotenone-treated rats exhibited significant behavioural symptoms, α-syn aggregation and degeneration of dopaminergic neurons, confirming the development of Parkinsonism. Significant upregulation of α-syn expression/phosphorylation and co-localization in TH+ve neurons in the SNpc of treated rats was observed. Further, the gene and protein analysis of HSP70, DNAJB6, and HSP105 were found to be upregulated and TH+ve neurons showed their co-localization with p-α-synser129 expression. The total proteomic analysis of SNpc correlated the altered cellular processes with cellular homeostasis imbalance. The observations of the present study provide an in vivo analysis of disaggregation-associated molecular chaperones in Parkinsonian or α-syn related conditions. The study can be helpful for further manipulation in the expression or activity of disaggregation-related chaperones for advanced therapeutic strategies and mechanistic studies in protein aggregation-associated diseases.

Keywords:  DNAJB; HSP70; Molecular chaperones; Parkinson's disease; Protein aggregation; Rotenone; α-Synuclein

DOI:  https://doi.org/10.1016/j.biocel.2025.106752
bioRxiv. 2025 Jan 28. pii: 2025.01.27.635090. [Epub ahead of print]

Nemo-like kinase disrupts nuclear import and drives TDP43 mislocalization in ALS.

Michael E Bekier, Emile Pinarbasi, Jack J Mesojedec, Layla Ghaffari, Martina de Majo, Erik Ullian, Mark Koontz, Sarah Coleman, Xingli Li, Elizabeth M H Tank, Jacob Waksmacki, Sami Barmada.

Cytoplasmic TDP43 mislocalization and aggregation are pathological hallmarks of amyotrophic lateral sclerosis (ALS). However, the initial cellular insults that lead to TDP43 mislocalization remain unclear. In this study, we demonstrate that Nemo-like kinase (NLK)-a proline-directed serine/threonine kinase-promotes the mislocalization of TDP43 and other RNA-binding proteins by disrupting nuclear import. NLK levels are selectively elevated in neurons exhibiting TDP43 mislocalization in ALS patient tissues, while genetic reduction of NLK reduces toxicity in human neuron models of ALS. Our findings suggest that NLK is a promising therapeutic target for neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.01.27.635090
J Am Chem Soc. 2025 Feb 17.

Chemical Synthesis Reveals Pathogenic Role of N-Glycosylation in Microtubule-Associated Protein Tau.

Wyatt C Powell, Ruiheng Jing, Morgane Herlory, Patrick Holland, Darya Poliyenko, Christopher C Ebmeier, Michael H B Stowell, Maciej A Walczak.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of tau protein aggregates. In this study, we investigated the effects of N-glycosylation on tau, focusing on its impact on aggregation and phase behavior. We chemically prepared homogeneous glycoproteins with high-mannose glycans or a single N-acetylglucosamine at the confirmed glycosylation sites in K18 and 2N4R tau. Our findings reveal that N-glycosylation significantly alters biophysical properties and potentially cellular functions of tau. Small glycans promote tau aggregation and liquid-liquid phase separation (LLPS), while larger glycans reduce these effects. High mannose glycans at N410 enhance phosphorylation by GSK3β, suggesting a pathological role in AD. Functional assays demonstrate that N-glycosylation does not impact microtubule polymerization dynamics but modulates aggregation kinetics and morphology. This research underscores the importance of glycosylation in tau pathology and opens new avenues for therapeutic interventions targeting glycan processing.

DOI: https://doi.org/10.1021/jacs.4c17873
Science. 2025 Feb 21. 387(6736): 892-900

Neuronal FAM171A2 mediates α-synuclein fibril uptake and drives Parkinson's disease.

Kai-Min Wu, Qian-Hui Xu, Yi-Qi Liu, Yi-Wei Feng, Si-Da Han, Ya-Ru Zhang, Shi-Dong Chen, Yu Guo, Bang-Sheng Wu, Ling-Zhi Ma, Yi Zhang, Yi-Lin Chen, Liu Yang, Zhao-Fei Yang, Yu-Jie Xiao, Ting-Ting Wang, Jue Zhao, Shu-Fen Chen, Mei Cui, Bo-Xun Lu, Wei-Dong Le, You-Sheng Shu, Keqiang Ye, Jia-Yi Li, Wen-Sheng Li, Jian Wang, Cong Liu, Peng Yuan, Jin-Tai Yu.

Neuronal accumulation and spread of pathological α-synuclein (α-syn) fibrils are key events in Parkinson's disease (PD) pathophysiology. However, the neuronal mechanisms underlying the uptake of α-syn fibrils remain unclear. In this work, we identified FAM171A2 as a PD risk gene that affects α-syn aggregation. Overexpressing FAM171A2 promotes α-syn fibril endocytosis and exacerbates the spread and neurotoxicity of α-syn pathology. Neuronal-specific knockdown of FAM171A2 expression shows protective effects. Mechanistically, the FAM171A2 extracellular domain 1 interacts with the α-syn C terminus through electrostatic forces, with >1000 times more selective for fibrils. Furthermore, we identified bemcentinib as an effective blocker of FAM171A2-α-syn fibril interaction with an in vitro binding assay, in cellular models, and in mice. Our findings identified FAM171A2 as a potential receptor for the neuronal uptake of α-syn fibrils and, thus, as a therapeutic target against PD.

DOI: https://doi.org/10.1126/science.adp3645
bioRxiv. 2025 Feb 02. pii: 2025.01.31.635912. [Epub ahead of print]

Polyamine biosynthesis dysregulation in Alzheimer's disease and Down syndrome cellular models.

Andres Sola, Alex Sandberg, Caitlin Pham, Alexandra Revier, Mia Hebinck, Alexandra Penney, Pablo Caviedes, Sunil Kumar, Ann-Charlotte Granholm, Daniel A Linseman, Daniel A Paredes.

BACKGROUND: Individuals with Down Syndrome (DS) frequently develop early onset Alzheimer's disease (AD) with pathological hallmarks closely resembling AD due to several triplicated genes on chromosome 21. Polyamines are small, organic molecules that play a pivotal role for growth and differentiation, and a dysregulation of polyamine pathways is implicated in AD pathology. However, their role in DS-associated AD is unclear.
METHODS: We analyzed polyamines and their metabolite levels in mouse hippocampal cells and human DS-AD and AD hippocampal tissue and assessed the effects of the ODC inhibitor difluoromethylornithine (DFMO) on Aβ42 aggregation and protein expression in DS fibroblasts.
RESULTS: Amyloid-β42 increased polyamine levels via ornithine decarboxylase (ODC) activation in a dose-dependent manner. DFMO reduced Aβ42 aggregation, decreased amyloid precursor protein (APP) levels, and normalized proteins linked to AD pathology in DS fibroblasts. Polyamine levels were elevated in DS-AD hippocampal tissue, with colocalization of ODC and Aβ42 aggregates.
CONCLUSION: These findings suggest that polyamine biosynthesis may exacerbate Aβ42 toxicity and APP expression, contributing to AD progression in DS. The ability of DFMO to reduce Aβ42 aggregation and restore protein homeostasis presents the polyamine pathway as a therapeutic target for DS-AD management.

DOI: https://doi.org/10.1101/2025.01.31.635912
bioRxiv. 2025 Feb 08. pii: 2025.02.07.636933. [Epub ahead of print]

Synergistic MAPT mutations as a platform to uncover modifiers of tau pathogenesis.

Miles R Bryan, Michael Almeida, Carli Opland, Jake McGillion-Moore, Hanna Trzeciakiewicz, Diamond King, Xu Tian, Jui-Heng Tseng, Jonathan Schisler, Ben Bahr, Todd J Cohen.

The natively unfolded tau protein is extremely soluble, which poses challenges when modeling neurofibrillary tangle (NFT) pathology in Alzheimers disease (AD). To overcome this hurdle, we combined P301L and S320F mutations (PL-SF) to generate a rapid and reliable platform to expedite the discovery of factors that modulate tau aggregation. Using this model, we evaluated heat-shock proteins (Hsp), traditionally linked to tau pathology, but whose role in AD remains enigmatic and controversial. In primary neurons, expression of Hsp70, but not Hsc70 or Hsp90, exacerbated tau aggregation. Conversely, lowering of Hsp70 by shRNA or a chaperone-deficient tau mutant (PL-SF-4delta) reduced tau phosphorylation and abrogated tau aggregation, highlighting Hsp70 as a key driver of tau aggregation. Functionally, mature aggregate-bearing neurons showed deficits in neuronal firing and network communication, while chaperone-binding deficient tau variants displayed reduced tau pathology and restored network properties. This study provides a powerful cell intrinsic model for accelerated tau aggregation, which can be harnessed to identify regulators of tau aggregation as promising therapeutic targets.

DOI: https://doi.org/10.1101/2025.02.07.636933
Sci Adv. 2025 Feb 21. 11(8): eadq2475

SUMO2/3 conjugation of TDP-43 protects against aggregation.

Enza Maria Verde, Francesco Antoniani, Laura Mediani, Valentina Secco, Samuele Crotti, Maria Celidea Ferrara, Jonathan Vinet, Aleksandra Sergeeva, Xiao Yan, Carsten Hoege, Cristiana Stuani, Francesca Paron, Tzu-Ting Kao, Rohit Shrivastava, Jolanta Polanowska, Aymeric Bailly, Alessandro Rosa, Eleonora Aronica, Anand Goswami, Neil Shneider, Anthony A Hyman, Emanuele Buratti, Dimitris Xirodimas, Titus M Franzmann, Simon Alberti, Serena Carra.

Cytosolic aggregation of the RNA binding protein TDP-43 (transactive response DNA-binding protein 43) is a hallmark of amyotrophic lateral sclerosis and frontotemporal dementia. Here, we report that during oxidative stress, TDP-43 becomes SUMO2/3-ylated by the SUMO E3 ligase protein PIAS4 (protein inhibitor of activated STAT 4) and enriches in cytoplasmic stress granules (SGs). Upon pharmacological inhibition of TDP-43 SUMO2/3-ylation or PIAS4 depletion, TDP-43 enrichment in SGs is accompanied by irreversible aggregation. In cells that are unable to assemble SGs, SUMO2/3-ylation of TDP-43 is strongly impaired, supporting the notion that SGs are compartments that promote TDP-43 SUMO2/3-ylation during oxidative stress. Binding of TDP-43 to UG-rich RNA antagonizes PIAS4-mediated SUMO2/3-ylation, while RNA dissociation promotes TDP-43 SUMO2/3-ylation. We conclude that SUMO2/3 protein conjugation is a cellular mechanism to stabilize cytosolic RNA-free TDP-43 against aggregation.

DOI: https://doi.org/10.1126/sciadv.adq2475
PLoS Biol. 2025 Feb;23(2): e3002974

The cholesterol 24-hydroxylase CYP46A1 promotes α-synuclein pathology in Parkinson's disease.

Lijun Dai, Jiannan Wang, Lanxia Meng, Xingyu Zhang, Tingting Xiao, Min Deng, Guiqin Chen, Jing Xiong, Wei Ke, Zhengyuan Hong, Lihong Bu, Zhentao Zhang.

Parkinson's disease (PD) is a neurodegenerative disease characterized by the death of dopaminergic neurons in the substantia nigra and the formation of Lewy bodies that are composed of aggregated α-synuclein (α-Syn). However, the factors that regulate α-Syn pathology and nigrostriatal dopaminergic degeneration remain poorly understood. Previous studies demonstrate cholesterol 24-hydroxylase (CYP46A1) increases the risk for PD. Moreover, 24-hydroxycholesterol (24-OHC), a brain-specific oxysterol that is catalyzed by CYP46A1, is elevated in the cerebrospinal fluid of PD patients. Herein, we show that the levels of CYP46A1 and 24-OHC are elevated in PD patients and increase with age in a mouse model. Overexpression of CYP46A1 intensifies α-Syn pathology, whereas genetic removal of CYP46A1 attenuates α-Syn neurotoxicity and nigrostriatal dopaminergic degeneration in the brain. Moreover, supplementation with exogenous 24-OHC exacerbates the mitochondrial dysfunction induced by α-Syn fibrils. Intracerebral injection of 24-OHC enhances the spread of α-Syn pathology and dopaminergic neurodegeneration via elevated X-box binding protein 1 (XBP1) and lymphocyte-activation gene 3 (LAG3) levels. Thus, elevated CYP46A1 and 24-OHC promote neurotoxicity and the spread of α-Syn via the XBP1-LAG3 axis. Strategies aimed at inhibiting the CYP46A1-24-OHC axis and LAG3 could hold promise as disease-modifying therapies for PD.

DOI: https://doi.org/10.1371/journal.pbio.3002974
bioRxiv. 2025 Jan 31. pii: 2025.01.28.635269. [Epub ahead of print]

Nuclear Import Defects Drive Cell Cycle Dysregulation in Neurodegeneration.

Jonathan Plessis-Belair, Taylor Russo, Markus Riessland, Roger B Sher.

Neurodegenerative diseases (NDDs) and other age-related disorders have been classically defined by a set of key pathological hallmarks. Two of these hallmarks, cell cycle dysregulation (CCD) and nucleocytoplasmic transport (NCT) defects, have long been debated as being either causal or consequential in the pathology of accelerated aging. Specifically, aberrant cell cycle activation in post-mitotic neurons has been shown to trigger neuronal cell death pathways and cellular senescence. Additionally, NCT has been observed to be progressively dysregulated during aging and in neurodegeneration, where the increased subcellular redistribution of nuclear proteins such as TAR DNA-Binding Protein-43 (TDP43) to the cytoplasm is a primary driver of many NDDs. However, the functional significance of NCT defects as either a primary driver or consequence of pathology, and how the redistribution of cell cycle machinery contributes to neurodegeneration, remains unclear. Here, we describe that pharmacological inhibition of importin-β nuclear import is capable of perturbing cell cycle machinery both in mitotic neuronal cell lines and post-mitotic primary neurons in vitro . Our Nemf R86S mouse model of motor neuron disease, characterized by nuclear import defects, further recapitulates the hallmarks of CCD in mitotic cell lines and in post-mitotic primary neurons in vitro , and in spinal motor neurons in vivo . The observed CCD is consistent with the transcriptional and phenotypical dysregulation observed in neuronal cell death and cellular senescence in NDDs. Together, this evidence suggests that impairment of nuclear import pathways resulting in CCD may be a common driver of pathology in neurodegeneration.

DOI: https://doi.org/10.1101/2025.01.28.635269
ACS Chem Biol. 2025 Feb 21.

Glycated α-Synuclein Renders Glial Cell Activation and Induces Degeneration of Dopaminergic Neurons: A Potential Implication for the Development of Parkinson's Disease.

Sayan Chatterjee, Arvind Verma, Harsh Thakkar, Ravi P Shah, Amit Khairnar.

Accumulation of misfolded α-synuclein (α-Syn) leads to the formation of Lewy bodies and is a major hallmark of Parkinson's disease (PD). The accumulation of α-Syn involves several post-translational modifications. Recently, though, glycation of α-Syn (advanced glycation end products) and activation of the receptor for advanced glycation end products (RAGE) have been linked to neuroinflammation, which leads to oxidative stress and accumulation of α-Syn. The present study aims to detect the effect of glycated α-Syn (gly-α-Syn)-induced synucleinopathy and loss of dopaminergic (DAergic) neurons in the development of PD. We isolated, purified, and prepared glycated recombinant human α-Syn using d-ribose. Gly-α-Syn was characterized by SDS-PAGE, intact mass analysis, and bottom-up peptide sequence through LC-HRMS/MS. The aggregation propensity of gly-α-Syn has been verified by morphological and shape analysis through Bio-AFM. The gly-α-Syn (2 μg/μL) was injected stereotaxically in the substantia nigra (SN) of ICR mice (3-4 months) and compared with the normal α-Syn, d ribose, and Tris-HCl/artificial CSF groups. 56 days postsurgery (DPS), an immunohistochemical examination was conducted to investigate gly-α-Syn-induced α-Syn accumulation, neuroinflammation, and neurodegeneration. The glycation of α-Syn led to the expression of transglutaminase 2 (TGM2), an enzyme that cross-linked with AGEs and may have caused the accumulation of α-Syn. Significant RAGE activation was also observed in gly-α-Syn, which might have induced glial cell activation, resulting in oxidative stress and, ultimately, apoptosis of dopaminergic neurons. It is important to note that TGM2, phosphorylated α-Syn, RAGE expression, and glial cell activation were only found in the gly-α-Syn group and not in the other groups. This suggests that gly-α-Syn plays a major role in synucleinopathy, neuroinflammation, and neurodegeneration. Overall, the present study demonstrated glycation of α-Syn as one of the important age-associated post-translational modifications that are involved in the degeneration of dopaminergic neurons, at least in a subset of the diabetic patients susceptible to developing PD.

DOI: https://doi.org/10.1021/acschembio.4c00777
Brain Res. 2025 Feb 13. pii: S0006-8993(25)00063-0. [Epub ahead of print]1852 149505

Outlook of SNCA (α-synuclein) transgenic fly models in delineating the sequel of mitochondrial dysfunction in Parkinson's disease.

Jennifer Sally Samson, Kalyanaraman Rajagopal, Venkatachalam Deepa Parvathi.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with mechanisms that results in loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) region of the brain. Being a complex heterogeneous disorder, there is a requisite in discovering the underlying molecular signatures that could potentially help in resolving challenges associated with diagnosis as well as therapeutic management. SNCA gene that encodes for the protein α-synuclein is widely known for its indispensable role in aggravating the progression of sporadic and familial PD, upon mutations. Likewise, mitochondrial dysfunction is inferred to be playing a central role in both forms of PD. Observations from experimental models and human PD cases displayed strong evidence for disruption of mitochondrial dynamics, inhibition of mitochondrial complex I protein's function and elevation in reactive oxygen species (ROS) by the toxic aggregation of α-synuclein. Further, recent studies have raised the possibility of an underlying relationship, where the α-synuclein toxicity is exacerbated by the mutant mitochondrial complex proteins and vice-versa. In this review, we provide an overview of mechanisms influencing α-synuclein-related neurodegeneration, particularly, emphasizing the role of SNCA (α-synuclein) gene in leading to altered mitochondrial biogenesis during PD. We have described how transgenic Drosophila models were reliable at recapitulating some of the essential characteristics of PD. In addition, we highlight the capability of utilizing transgenic fly models in deciphering the altered α-synuclein toxicity and mitochondrial dysfunction, as induced by defects in the mitochondrial DNA.

Keywords:  Drosophila melanogaster; Mitochondrial dysfunction; Oxidative stress; Parkinson’s disease; SNCA (α-synuclein); Targeted enhancer/suppressor screening

DOI:  https://doi.org/10.1016/j.brainres.2025.149505