bims-axbals 2024-12-29 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2024–12–29
thirty-one papers selected by
TJ Krzystek, ALS Therapy Development Institute

A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in an AAV-C9ORF72 (G4C2)66 mouse model.
A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in a AAV- C9ORF72 (G 4 C 2 ) 66 mouse model.
CHMP2B promotes CHMP7 mediated nuclear pore complex injury in sporadic ALS.
Neuronal constitutive endolysosomal perforations enable α-synuclein aggregation by internalized PFFs.
Targeted long-read sequencing to quantify methylation of the C9orf72 repeat expansion.
Targeting STMN2 for neuroprotection and neuromuscular recovery in Spinal Muscular Atrophy: evidence from in vitro and in vivo SMA models.
The cellular and extracellular proteomic signature of human dopaminergic neurons carrying the LRRK2 G2019S mutation.
Development of a Sensitive and Reliable Meso Scale Discovery-Based Electrochemiluminescence Immunoassay to Quantify TDP-43 in Human Biofluids.
Dysregulation of synaptic transcripts underlies network abnormalities in ALS patient-derived motor neurons.
The design and development of LRRK2 inhibitors as novel therapeutics for Parkinson's disease.
Concomitant Amyotrophic Lateral Sclerosis and Rheumatoid Arthritis: A Case Report.
Decreased Hsp90 activity protects against TDP-43 neurotoxicity in a C. elegans model of amyotrophic lateral sclerosis.
Oligodendrocytes in Huntington's Disease: A Review of Oligodendrocyte Pathology and Current Cell Reprogramming Approaches for Oligodendrocyte Modelling of Huntington's Disease.
Amyotrophic lateral sclerosis caused by SOD1 variants: from genetic discovery to disease prevention.
Isolating Synaptic Vesicles from Neurospheres for Proteomics.
Synaptic sabotage: How Tau and α-Synuclein undermine synaptic health.
Preventing excessive autophagy protects from the pathology of mtDNA mutations in Drosophila melanogaster.
Tagless LysoIP for immunoaffinity enrichment of native lysosomes from clinical samples.
Plasma Extracellular Vesicle-Associated Proteins as Promising Diagnostic Biomarkers of Age-Related Macular Degeneration.
Melatonin Reduces Mito-Inflammation in Ischaemic Hippocampal HT22 Cells and Modulates the cGAS-STING Cytosolic DNA Sensing Pathway and FGF21 Release.
Stabilization of mitochondria-associated endoplasmic reticulum membranes regulates Aβ generation in a three-dimensional neural model of Alzheimer's disease.
Antibody-mediated clearance of an ER-resident aggregate that causes glaucoma.
NOVEL APPROACHES IN TARGETING MEMBRANE AND SECRETED PROTEINS FOR LYSOSOMAL DEGRADATION.
Engineering the 3D structure of organoids.
Identifying the Pathogenicity of a Novel NPRL3 Missense Mutation Using Personalized Cortical Organoid Model of Focal Cortical Dysplasia.
Quantitative Live Imaging Reveals Phase Dependency of PDAC Patient-Derived Organoids on ERK and AMPK Activity.
Beyond consciousness: Ethical, legal, and social issues in human brain organoid research and application.
TMEM106B C-terminal fragments aggregate and drive neurodegenerative proteinopathy in transgenic Caenorhabditis elegans.
Decision Tree for Protein Biomarker Selection for Clinical Applications.
Free-living monitoring of ALS progression in upper limbs using wearable accelerometers.
An efficient injection protocol for Drosophila larvae.

Acta Neuropathol Commun. 2024 Dec 26. 12(1): 203

A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in an AAV-C9ORF72 (G4C2)66 mouse model.

Emily G Thompson, Olivia Spead, Suleyman C Akerman, Carrie Curcio, Benjamin L Zaepfel, Erica R Kent, Thomas Philips, Balaji G Vijayakumar, Anna Zacco, Weibo Zhou, Guhan Nagappan, Jeffrey D Rothstein.

  The G4C2 hexanucleotide repeat expansion in C9ORF72 is the major genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Despite considerable efforts, the development of mouse models of C9-ALS/FTD useful for therapeutic development has proven challenging due to the intricate interplay of genetic and molecular factors underlying this neurodegenerative disorder, in addition to species differences. This study presents a robust investigation of the cellular pathophysiology and behavioral outcomes in a previously described AAV mouse model of C9-ALS expressing 66 G4C2 hexanucleotide repeats. The model displays key molecular ALS pathological markers including RNA foci, dipeptide repeat (DPR) protein aggregation, p62 positive stress granule formation as well as mild gliosis. However, the AAV-(G4C2)66 mouse model in this study has marginal neurodegeneration with negligible neuronal loss, or clinical deficits. Human C9orf72 is typically associated with altered TAR DNA-binding protein (TDP-43) function, yet studies of this rodent model revealed no significant evidence of TDP-43 dysfunction. While our findings indicate and support that this is a highly valuable robust and pharmacologically tractable model for investigating the molecular mechanisms and cellular consequences of (G4C2) repeat driven DPR pathology, it is not suitable for investigating the development of disease- associated TDP-43 dysfunction or clinical impairment. Our findings underscore the complexity of ALS pathogenesis involving genetic mutations and protein dysregulation and highlight the need for more comprehensive model systems that reliably replicate the multifaceted cellular and behavioral aspects of C9-ALS.

Keywords:  Amyotrophic lateral sclerosis; C9orf72 repeat expansion; Dipeptide repeats; GFAP; NfL; P62

DOI:  https://doi.org/10.1186/s40478-024-01911-y
Res Sq. 2024 Dec 10. pii: rs.3.rs-5221595. [Epub ahead of print]

A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in a AAV- C9ORF72 (G 4 C 2 ) 66 mouse model.

Emily G Thompson, Olivia Spead, S Can Akerman, Carrie Curcio, Benjamin L Zaepfel, Erica R Kent, Thomas Philips, Balaji G Vijayakumar, Anna Zacco, Weibo Zhou, Guhan Nagappan, Jeffrey D Rothstein.

The G 4 C 2 hexanucleotide repeat expansion in C9ORF72 is the major genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Despite considerable efforts, the development of mouse models of C9-ALS/FTD useful for therapeutic development has proven challenging due to the intricate interplay of genetic and molecular factors underlying this neurodegenerative disorder, in addition to species differences. This study presents a robust investigation of the cellular pathophysiology and behavioral outcomes in a previously described AAV mouse model of C9-ALS expressing 66 G 4 C 2 hexanucleotide repeats. The model displays key molecular ALS pathological markers including RNA foci, dipeptide repeat (DPR) protein aggregation, p62 positive stress granule formation as well as mild gliosis. However, the AAV-(G 4 C 2 ) 66 mouse model in this study has marginal neurodegeneration with negligible neuronal loss, or clinical deficits. Human C9orf72 is typically associated with altered TAR DNA-binding protein (TDP-43) function, yet studies of this rodent model revealed no significant evidence of TDP-43 dysfunction. While our findings indicate and support that this is a highly valuable robust and pharmacologically tractable model for investigating the molecular mechanisms and cellular consequences of (G 4 C 2 ) repeat driven DPR pathology, it is not suitable for investigating the development of disease- associated TDP-43 dysfunction or clinical impairment. Our findings underscore the complexity of ALS pathogenesis involving genetic mutations and protein dysregulation and highlight the need for more comprehensive model systems that reliably replicate the multifaceted cellular and behavioral aspects of C9-ALS.

DOI: https://doi.org/10.21203/rs.3.rs-5221595/v1
Acta Neuropathol Commun. 2024 Dec 21. 12(1): 199

CHMP2B promotes CHMP7 mediated nuclear pore complex injury in sporadic ALS.

Olivia Keeley, Emma Mendoza, Druv Menon, Alyssa N Coyne.

Alterations to the composition and function of neuronal nuclear pore complexes (NPCs) have been documented in multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis (ALS). Moreover, recent work has suggested that injury to the NPC can at least in part contribute to TDP-43 loss of function and mislocalization, a pathological hallmark of ALS and related neurodegenerative diseases. Collectively, these studies highlight a role for disruptions in NPC homeostasis and surveillance as a significant pathophysiologic event in neurodegeneration. The ESCRT-III nuclear surveillance pathway plays a critical role in the surveillance and maintenance of NPCs and the surrounding nuclear environment. Importantly, pathologic alterations to this pathway and its protein constituents have been implicated in neurodegenerative diseases such as ALS. However, the mechanism by which this pathway contributes to disease associated alterations in the NPC remains unknown. Here we use an induced pluripotent stem cell (iPSC) derived neuron (iPSN) model of sALS to demonstrate that CHMP7/ESCRT-III nuclear maintenance/surveillance is overactivated in sALS neurons. This overactivation is dependent upon the ESCRT-III protein CHMP2B and sustained CHMP2B dependent "activation" is sufficient to contribute to pathologic CHMP7 nuclear accumulation and POM121 reduction. Importantly, partial knockdown of CHMP2B was sufficient to alleviate NPC injury and downstream TDP-43 dysfunction in sALS neurons thereby highlighting CHMP2B as a potential therapeutic target in disease.

DOI: https://doi.org/10.1186/s40478-024-01916-7
J Cell Biol. 2025 Feb 03. pii: e202401136. [Epub ahead of print]224(2):

Neuronal constitutive endolysosomal perforations enable α-synuclein aggregation by internalized PFFs.

Anwesha Sanyal, Gustavo Scanavachi, Elliott Somerville, Anand Saminathan, Athul Nair, Ricardo F Bango Da Cunha Correia, Beren Aylan, Ewa Sitarska, Athanasios Oikonomou, Nikos S Hatzakis, Tom Kirchhausen.

Endocytosis, required for the uptake of receptors and their ligands, can also introduce pathological aggregates such as α-synuclein (α-syn) in Parkinson's Disease. We show here the unexpected presence of intrinsically perforated endolysosomes in neurons, suggesting involvement in the genesis of toxic α-syn aggregates induced by internalized preformed fibrils (PFFs). Aggregation of endogenous α-syn in late endosomes and lysosomes of human iPSC-derived neurons (iNs), seeded by internalized α-syn PFFs, caused the death of the iNs but not of the parental iPSCs and non-neuronal cells. Live-cell imaging of iNs showed constitutive perforations in ∼5% of their endolysosomes. These perforations, identified by 3D electron microscopy in iNs and CA1 pyramidal neurons and absent in non-neuronal cells, may facilitate cytosolic access of endogenous α-syn to PFFs in the lumen of endolysosomes, triggering aggregation. Inhibiting the PIKfyve phosphoinositol kinase reduced α-syn aggregation and associated iN death, even with ongoing PFF endolysosomal entry, suggesting that maintaining endolysosomal integrity might afford a therapeutic strategy to counteract synucleinopathies.

DOI: https://doi.org/10.1083/jcb.202401136
Mol Neurodegener. 2024 Dec 21. 19(1): 99

Targeted long-read sequencing to quantify methylation of the C9orf72 repeat expansion.

Evan Udine, NiCole A Finch, Mariely DeJesus-Hernandez, Jazmyne L Jackson, Matthew C Baker, Siva Arumugam Saravanaperumal, Eric Wieben, Mark T W Ebbert, Jaimin Shah, Leonard Petrucelli, Rosa Rademakers, Björn Oskarsson, Marka van Blitterswijk.

   BACKGROUND: The gene C9orf72 harbors a non-coding hexanucleotide repeat expansion known to cause amyotrophic lateral sclerosis and frontotemporal dementia. While previous studies have estimated the length of this repeat expansion in multiple tissues, technological limitations have impeded researchers from exploring additional features, such as methylation levels.
METHODS: We aimed to characterize C9orf72 repeat expansions using a targeted, amplification-free long-read sequencing method. Our primary goal was to determine the presence and subsequent quantification of observed methylation in the C9orf72 repeat expansion. In addition, we measured the repeat length and purity of the expansion. To do this, we sequenced DNA extracted from blood for 27 individuals with an expanded C9orf72 repeat.
RESULTS: For these individuals, we obtained a total of 7,765 on-target reads, including 1,612 fully covering the expanded allele. Our in-depth analysis revealed that the expansion itself is methylated, with great variability in total methylation levels observed, as represented by the proportion of methylated CpGs (13 to 66%). Interestingly, we demonstrated that the expanded allele is more highly methylated than the wild-type allele (P-Value = 2.76E-05) and that increased methylation levels are observed in longer repeat expansions (P-Value = 1.18E-04). Furthermore, methylation levels correlate with age at collection (P-Value = 3.25E-04) as well as age at disease onset (P-Value = 0.020). Additionally, we detected repeat lengths up to 4,088 repeats (~ 25 kb) and found that the expansion contains few interruptions in the blood.
CONCLUSIONS: Taken together, our study demonstrates robust ability to quantify methylation of the expanded C9orf72 repeat, capturing differences between individuals harboring this expansion and revealing clinical associations.

Keywords:  Amyotrophic lateral sclerosis; C9orf72; Frontotemporal dementia; Long-read sequencing; Methylation; Repeat expansions

DOI:  https://doi.org/10.1186/s13024-024-00790-0
Cell Mol Life Sci. 2024 Dec 27. 82(1): 29

Targeting STMN2 for neuroprotection and neuromuscular recovery in Spinal Muscular Atrophy: evidence from in vitro and in vivo SMA models.

Elisa Pagliari, Michela Taiana, Paolo Manzini, Luca Sali, Lorenzo Quetti, Letizia Bertolasi, Samanta Oldoni, Valentina Melzi, Giacomo Comi, Stefania Corti, Monica Nizzardo, Federica Rizzo.

  The development of ground-breaking Survival Motor Neuron (SMN) replacement strategies has revolutionized the field of Spinal Muscular Atrophy (SMA) research. However, the limitations of these therapies have now become evident, highlighting the need for the development of complementary targets beyond SMN replacement. To address these challenges, here we explored, in in vitro and in vivo disease models, Stathmin-2 (STMN2), a neuronal microtubule regulator implicated in neurodegenerative diseases like Amyotrophic Lateral Sclerosis (ALS), as a novel SMN-independent target for SMA therapy. Our findings revealed that STMN2 overexpression effectively restored axonal growth and outgrowth defects in induced pluripotent stem cell-(iPSC)-derived motor neurons (MNs) from SMA patients. Intracerebroventricular administration of adeno-associated virus serotype 9 (AAV9) carrying Stmn2 cDNA significantly ameliorated survival rates, motor functions, muscular and neuromuscular junction pathological features in SMA mice, mirrored by in vitro outcomes. Overall, this pioneering study not only provides insight into the therapeutic potential of STMN2 in SMA, but also suggests its broader applications for MN diseases, marking a substantial step forward in addressing the multifaceted challenges of neurological diseases treatment.

Keywords:  Modifier gene; Motor neurons; SMA mouse; SMN; STMN2

DOI:  https://doi.org/10.1007/s00018-024-05550-3
Front Neurosci. 2024 ;18 1502246

The cellular and extracellular proteomic signature of human dopaminergic neurons carrying the LRRK2 G2019S mutation.

Felix Knab, Giambattista Guaitoli, Mohamed Ali Jarboui, Felix von Zweydorf, Fatma Busra Isik, Franziska Klose, Anto Praveen Rajkumar, Thomas Gasser, Christian Johannes Gloeckner.

   Background: Extracellular vesicles are easily accessible in various biofluids and allow the assessment of disease-related changes in the proteome. This has made them a promising target for biomarker studies, especially in the field of neurodegeneration where access to diseased tissue is very limited. Genetic variants in the LRRK2 gene have been linked to both familial and sporadic forms of Parkinson's disease. With LRRK2 inhibitors entering clinical trials, there is an unmet need for biomarkers that reflect LRRK2-specific pathology and target engagement.
Methods: In this study, we used induced pluripotent stem cells derived from a patient with Parkinson's disease carrying the LRRK2 G2019S mutation and an isogenic gene-corrected control to generate human dopaminergic neurons. We isolated extracellular vesicles and neuronal cell lysates and characterized their proteomic signature using data-independent acquisition proteomics. Then, we performed differential expression analysis to identify dysregulated proteins in the mutated line. We used Metascape and gene ontology enrichment analysis on the dysregulated proteomes to identify changes in associated functional networks.
Results: We identified 595 significantly differentially regulated proteins in extracellular vesicles and 3,205 in cell lysates. We visualized functionally relevant protein-protein interaction networks and identified key regulators within the dysregulated proteomes. Using gene ontology, we found a close association with biological processes relevant to neurodegeneration and Parkinson's disease. Finally, we focused on proteins that were dysregulated in both the extracellular and cellular proteomes. We provide a list of ten biomarker candidates that are functionally relevant to neurodegeneration and linked to LRRK2-associated pathology, for example, the sonic hedgehog signaling molecule, a protein that has tightly been linked to LRRK2-related disruption of cilia function.
Conclusion: In conclusion, we characterized the cellular and extracellular proteome of dopaminergic neurons carrying the LRRK2 G2019S mutation and proposed an experimentally based list of biomarker candidates for future studies.

Keywords:  LRRK2; Parkinson’s disease; biomarker; extracellular vesicle; induced pluripotent stem cell

DOI:  https://doi.org/10.3389/fnins.2024.1502246
Biosensors (Basel). 2024 Nov 28. pii: 578. [Epub ahead of print]14(12):

Development of a Sensitive and Reliable Meso Scale Discovery-Based Electrochemiluminescence Immunoassay to Quantify TDP-43 in Human Biofluids.

Jiyan An, Lathika Gopalakrishnan, Vanessa Ortega, Justin Saul, Renu Kadali, Robert Bowser.

  Transactive response DNA-binding protein of 43 kDa (TDP-43) is a major component of pathological inclusions in various neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. The detection of TDP-43 in biofluids is crucial for the development of diagnostic and prognostic indicators of disease and therapeutic development for TDP-43-related proteinopathies. Despite its potential as a biomarker for numerous neurological disorders, the lack of a sensitive and reproducible TDP-43 assay hinders progress in TDP-43-based therapy development, underscoring the need for an effective and standardized method for accurate quantification. Addressing the limitations of sensitivity and reproducibility in existing assays, in this study, we developed and validated a highly sensitive electrochemiluminescence immunoassay on the Meso Scale Discovery platform. The assay demonstrated the detection of full-length TDP-43 in human biofluids with a limit of detection of 4pg/mL, a working range of 4-20,000 pg/mL, and a total assay time of 16 h. In this study, we developed and validated a sensitive immunoassay for the detection of full-length TDP-43 in human biofluids using the Meso Scale Discovery platform. We used this immunoassay to quantify TDP-43 levels in the plasma and serum of healthy controls and ALS patients. Our results indicate a reduction in full-length TDP-43 in the blood of ALS patients compared to healthy controls.

Keywords:  ALS; MSD; TDP-43; biomarker; immunoassay; neurodegenerative disease

DOI:  https://doi.org/10.3390/bios14120578
Am J Physiol Cell Physiol. 2024 Dec 26.

Dysregulation of synaptic transcripts underlies network abnormalities in ALS patient-derived motor neurons.

Anna M Kollstrøm, Nicholas Christiansen, Axel Sandvig, Ioanna Sandvig.

  Amyotrophic lateral sclerosis (ALS) is characterized by dysfunction and loss of upper and lower motor neurons. Several studies have identified structural and functional alterations in the motor neurons before the manifestation of symptoms, yet the underlying cause of such alterations and how they contribute to the progressive degeneration of affected motor neuron networks remain unclear. Importantly, the short and long-term spatiotemporal dynamics of neuronal network activity make it challenging to discern how ALS-related network reconfigurations emerge and evolve. To address this, we systematically monitored the structural and functional dynamics of motor neuron networks with a confirmed endogenous C9orf72 mutation. We show that ALS patient-derived motor neurons display time-dependent neural network dysfunction, specifically reduced firing rate and spike amplitude, impaired bursting, but higher overall synchrony in network activity. These changes coincided with altered neurite outgrowth and branching within the networks. Moreover, transcriptional analyses revealed dysregulation of molecular pathways involved in synaptic development and maintenance, neurite outgrowth and cell adhesion, suggesting impaired synaptic stabilization. This study identifies early synaptic dysfunction as a contributing mechanism resulting in network-wide structural and functional compensation, which may over time render the networks vulnerable to neurodegeneration.

Keywords:  connectivity; electrophysiology; human induced pluripotent stem cells; micro-electrode arrays; transcriptomics

DOI:  https://doi.org/10.1152/ajpcell.00725.2024
Future Med Chem. 2024 Dec 24. 1-16

The design and development of LRRK2 inhibitors as novel therapeutics for Parkinson's disease.

Xiaoxue Bai, Jiawei Zhu, Yao Chen, Haopeng Sun.

  Parkinson's disease (PD) is a common neurodegenerative disease affecting nearly 10 million people worldwide and placing a heavy medical burden on both society and families. However, due to the complexity of its pathological mechanisms, current treatments for PD can only alleviate patients' symptoms. Therefore, novel therapeutic strategies are urgently sought in clinical practice. Leucine-rich repeat kinase 2 (LRRK2) has emerged as a highly promising target for PD therapy. Missense mutations within the structural domain of LRRK2, the most common genetic risk factor for PD, lead to abnormally elevated kinase activity and increase the risk of developing PD. In this article, we provide a comprehensive overview of the structure, biological function, and pathogenic mutations of LRRK2, and examine recent advances in the development of LRRK2 inhibitors. We hope that this article will provide a reference for the design of novel LRRK2 inhibitors based on summarizing the facts and elucidating the viewpoints.

Keywords:  ATP-competitive inhibitors; Leucine-rich repeat kinase 2; Parkinson’s disease; kinase inhibitors; mutations; neurodegeneration

DOI:  https://doi.org/10.1080/17568919.2024.2444875
Cureus. 2024 Nov;16(11): e74301

Concomitant Amyotrophic Lateral Sclerosis and Rheumatoid Arthritis: A Case Report.

Mustafa Alhayali.

  Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative motor neuron disease that leads to a gradual loss of motor neurons manifesting as progressive weakness, dysarthria, and respiratory decline, with a relatively short life expectancy. Rheumatoid arthritis (RA) is an autoimmune disorder characterized by polyarthritis and affects multiple systems. Motor neuron involvement is rare in rheumatoid arthritis. Here, we report a unique case of a patient with an established diagnosis of ALS who later developed seropositive RA. A 58-year-old male from Baghdad presented to our center with polyarticular joint pain, stiffness, and swelling for about four months, the patient had a history of progressive neurological deficits. The final diagnosis was seropositive rheumatoid arthritis with concomitant amyotrophic lateral sclerosis. While the patient's joint symptoms responded well to methotrexate and prednisolone, he continued to experience a neurological decline. This is one of the few reported cases of concurrent ALS and RA, highlighting the complexity of managing overlapping neurodegenerative and autoimmune conditions.

Keywords:  amyotrophic lateral sclerosis; methotrexate; motor neuron disease; rare association; rheumatoid arthritis

DOI:  https://doi.org/10.7759/cureus.74301
PLoS Genet. 2024 Dec 26. 20(12): e1011518

Decreased Hsp90 activity protects against TDP-43 neurotoxicity in a C. elegans model of amyotrophic lateral sclerosis.

Laura Garcia-Toscano, Heather N Currey, Joshua C Hincks, Jade G Stair, Nicolas J Lehrbach, Nicole F Liachko.

Neuronal inclusions of hyperphosphorylated TDP-43 are hallmarks of disease for most patients with amyotrophic lateral sclerosis (ALS). Mutations in TARDBP, the gene coding for TDP-43, can cause some cases of familial inherited ALS (fALS), indicating dysfunction of TDP-43 drives disease. Aggregated, phosphorylated TDP-43 may contribute to disease phenotypes; alternatively, TDP-43 aggregation may be a protective cellular response sequestering toxic protein away from the rest of the cell. The heat shock responsive chaperone Hsp90 has been shown to interact with TDP-43 and stabilize its normal conformation; however, it is not known whether this interaction contributes to neurotoxicity in vivo. Using a C. elegans model of fALS mutant TDP-43 proteinopathy, we find that loss of function of HSP-90 protects against TDP-43 neurotoxicity and subsequent neurodegeneration in adult animals. This protection is accompanied by a decrease in both total and phosphorylated TDP-43 protein. We also find that hsp-90 mutation or inhibition upregulates key stress responsive heat shock pathway gene expression, including hsp-70 and hsp-16.1, and we demonstrate that normal levels of hsp-16.1 are required for hsp-90 mutation effects on TDP-43. We also observe that the neuroprotective effect due to HSP-90 dysfunction does not involve direct regulation of proteasome activity in C. elegans. Our data demonstrate for the first time that Hsp90 chaperone activity contributes to adverse outcomes in TDP-43 proteinopathies in vivo using a whole animal model of ALS.

DOI: https://doi.org/10.1371/journal.pgen.1011518
J Neurosci Res. 2024 Dec;102(12): e70010

Oligodendrocytes in Huntington's Disease: A Review of Oligodendrocyte Pathology and Current Cell Reprogramming Approaches for Oligodendrocyte Modelling of Huntington's Disease.

Amelie Marie Back, Bronwen Connor, Amy McCaughey-Chapman.

  Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder traditionally characterized by the selective loss of medium spiny neurons in the basal ganglia. However, it has become apparent that white matter injury and oligodendrocyte dysfunction precede the degeneration of medium spiny neurons, garnering interest as a key pathogenic mechanism of HD. Oligodendrocytes are glial cells found within the central nervous system involved in the production of myelin and the myelination of axons. Myelin is a lipid-rich sheath that wraps around axons, facilitating signal conduction and neuronal viability. The degeneration of myelin hinders effective communication and leaves neurons vulnerable to external damage and subsequent degeneration. Abnormalities in oligodendrocyte maturation have been established in the HD human brain, however, investigations into the underlying dysfunction of human oligodendrocytes in HD are limited. This review will detail the involvement of oligodendrocytes and white matter damage in HD. Recent developments in modeling human-specific oligodendrocyte pathology in HD will be discussed, with a particular focus on emerging somatic cell reprogramming approaches.

Keywords:  Huntington's disease; direct cell reprogramming; myelin; oligodendrocyte; white matter

DOI:  https://doi.org/10.1002/jnr.70010
Lancet Neurol. 2025 Jan;pii: S1474-4422(24)00479-4. [Epub ahead of print]24(1): 77-86

Amyotrophic lateral sclerosis caused by SOD1 variants: from genetic discovery to disease prevention.

Michael Benatar, Janice Robertson, Peter Munch Andersen.

Pathogenic variants in the superoxide dismutase 1 (SOD1) gene were the first identified genetic cause of amyotrophic lateral sclerosis (ALS), in 1993. This discovery enabled the development of transgenic rodent models for studying the biology of SOD1 ALS. The understanding that SOD1 ALS is driven by a toxic gain-of-function mutation has led to therapeutic strategies that aim to lower concentrations of SOD1 protein, an endeavour that has been complicated by the phenotypic heterogeneity of SOD1 ALS. The successful development of genetically targeted therapies to reduce SOD1 expression, together with a better understanding of pre-symptomatic disease and the discovery of neurofilament light protein as a susceptibility/risk biomarker that predicts phenoconversion, has ushered in a new era of trials that aim to prevent clinically manifest SOD1 ALS. The 30-year journey from gene discovery to gene therapy has not only uncovered the pathophysiology of SOD1 ALS, but has also facilitated the development of biomarkers that should aid therapy development for all forms of ALS.

DOI: https://doi.org/10.1016/S1474-4422(24)00479-4
Methods Mol Biol. 2025 ;2884 207-223

Isolating Synaptic Vesicles from Neurospheres for Proteomics.

Caroline Brandão-Teles, Giuliana S Zuccoli, Marcelo Ganzella, Victor Corasolla Carregari, Linda Olsthoorn, Érica de Almeida Duque, Carolina Demarchi Munhoz, Reinhard Jahn, Daniel Martins-de-Souza, Fernanda Crunfli.

  This chapter presents an optimized method for isolating synaptic vesicles (SVs) from neurospheres derived from human induced pluripotent stem cells (hiPSCs). The protocol begins with neurosphere cultivation to achieve mature neurons, which is essential for the functional studies of neuronal activity. Following this, neurosphere-derived synaptosomes are isolated, and SVs are enriched through differential centrifugation. The method culminates in the proteomic analysis of SVs using nano-liquid chromatography coupled with high-resolution tandem mass spectrometry (nanoLC-MS/MS), providing a detailed proteome profile of the isolated vesicles. This protocol can contribute to the understanding of SV molecular heterogeneity and the mechanisms of neurotransmitter uptake and release and be applied to the field of research in neurological and neuropsychiatric disorders.

Keywords:  Neural stem cell; Neurospheres; Proteomics; Synapse vesicles; Vesicle isolation

DOI:  https://doi.org/10.1007/978-1-0716-4298-6_14
J Cell Biol. 2025 Feb 03. pii: e202409104. [Epub ahead of print]224(2):

Synaptic sabotage: How Tau and α-Synuclein undermine synaptic health.

Valerie Uytterhoeven, Patrik Verstreken, Eliana Nachman.

Synaptic dysfunction is one of the earliest cellular defects observed in Alzheimer's disease (AD) and Parkinson's disease (PD), occurring before widespread protein aggregation, neuronal loss, and cognitive decline. While the field has focused on the aggregation of Tau and α-Synuclein (α-Syn), emerging evidence suggests that these proteins may drive presynaptic pathology even before their aggregation. Therefore, understanding the mechanisms by which Tau and α-Syn affect presynaptic terminals offers an opportunity for developing innovative therapeutics aimed at preserving synapses and potentially halting neurodegeneration. This review focuses on the molecular defects that converge on presynaptic dysfunction caused by Tau and α-Syn. Both proteins have physiological roles in synapses. However, during disease, they acquire abnormal functions due to aberrant interactions and mislocalization. We provide an overview of current research on different essential presynaptic pathways influenced by Tau and α-Syn. Finally, we highlight promising therapeutic targets aimed at maintaining synaptic function in both tauopathies and synucleinopathies.

DOI: https://doi.org/10.1083/jcb.202409104
Nat Commun. 2024 Dec 23. 15(1): 10719

Preventing excessive autophagy protects from the pathology of mtDNA mutations in Drosophila melanogaster.

Najla El Fissi, Florian A Rosenberger, Kai Chang, Alissa Wilhalm, Tom Barton-Owen, Fynn M Hansen, Zoe Golder, David Alsina, Anna Wedell, Matthias Mann, Patrick F Chinnery, Christoph Freyer, Anna Wredenberg.

Aberration of mitochondrial function is a shared feature of many human pathologies, characterised by changes in metabolic flux, cellular energetics, morphology, composition, and dynamics of the mitochondrial network. While some of these changes serve as compensatory mechanisms to maintain cellular homeostasis, their chronic activation can permanently affect cellular metabolism and signalling, ultimately impairing cell function. Here, we use a Drosophila melanogaster model expressing a proofreading-deficient mtDNA polymerase (POLγexo-) in a genetic screen to find genes that mitigate the harmful accumulation of mtDNA mutations. We identify critical pathways associated with nutrient sensing, insulin signalling, mitochondrial protein import, and autophagy that can rescue the lethal phenotype of the POLγexo- flies. Rescued flies, hemizygous for dilp1, atg2, tim14 or melted, normalise their autophagic flux and proteasome function and adapt their metabolism. Mutation frequencies remain high with the exception of melted-rescued flies, suggesting that melted may act early in development. Treating POLγexo- larvae with the autophagy activator rapamycin aggravates their lethal phenotype, highlighting that excessive autophagy can significantly contribute to the pathophysiology of mitochondrial diseases. Moreover, we show that the nucleation process of autophagy is a critical target for intervention.

DOI: https://doi.org/10.1038/s41467-024-55559-2
J Clin Invest. 2024 Dec 26. pii: e183592. [Epub ahead of print]

Tagless LysoIP for immunoaffinity enrichment of native lysosomes from clinical samples.

Daniel Saarela, Pawel Lis, Sara Gomes, Raja S Nirujogi, Wentao Dong, Eshaan S Rawat, Sophie Glendinning, Karolina Zeneviciute, Enrico Bagnoli, Rotimi Fasimoye, Cindy Lin, Kwamina Nyame, Fanni A Boros, Friederike Zunke, Frederic Lamoliatte, Sadik Elshani, Matthew Jaconelli, Judith Jm Jans, Margriet A Huisman, Christian Posern, Lena M Westermann, Angela Schulz, Peter M van Hasselt, Dario R Alessi, Monther Abu-Remaileh, Esther M Sammler.

  Lysosomes are implicated in a wide spectrum of human diseases including monogenic lysosomal storage disorders (LSDs), age-associated neurodegeneration and cancer. Profiling lysosomal content using tag-based lysosomal immunoprecipitation (LysoTagIP) in cell and animal models has substantially moved the field forward, but studying lysosomal dysfunction in human patients remains challenging. Here, we report the development of the 'tagless LysoIP' method, designed to enable the rapid enrichment of lysosomes, via immunoprecipitation, using the endogenous integral lysosomal membrane protein TMEM192, directly from clinical samples and human cell lines (e.g., induced pluripotent stem cell derived neurons). Isolated lysosomes were intact and suitable for subsequent multimodal omics analyses. To validate our approach, we applied the tagless LysoIP to enrich lysosomes from peripheral blood mononuclear cells derived from fresh blood of healthy donors and patients with CLN3 disease, an autosomal recessive neurodegenerative LSD. Metabolic profiling of isolated lysosomes revealed massive accumulation of glycerophosphodiesters (GPDs) in patients' lysosomes. Interestingly, a patient with a milder phenotype and genotype displayed lower accumulation of lysosomal GPDs, consistent with their potential role as disease biomarkers. Altogether, the tagless LysoIP provides a framework to study native lysosomes from patient samples, identify disease biomarkers, and discover human-relevant disease mechanisms.

Keywords:  Cell biology; Genetic diseases; Lysosomes; Neurodegeneration; Neuroscience

DOI:  https://doi.org/10.1172/JCI183592
Discov Med. 2024 Dec;36(191): 2356-2364

Plasma Extracellular Vesicle-Associated Proteins as Promising Diagnostic Biomarkers of Age-Related Macular Degeneration.

Rouan Chen, Yuxuan Wu, Yiming Fang, Tian Lan, Wei Shi.

   BACKGROUND: Age-related macular degeneration (AMD) is a significant factor causing blindness in adults. However, the clinical diagnosis of AMD is relatively challenging, due to the shortcomings of the existing clinical examination methods and the latent period of retinal damage before macular degeneration becomes apparent. This study aims to explore the potential of extracellular vesicles (EVs) protein chips for early diagnosis of AMD using patients' plasma samples.
METHODS: To achieve early diagnosis of AMD, this study utilized a high-throughput platform for liquid biopsy based on EVs protein chips. Forty AMD patients and 41 normal individuals were recruited. Through machine learning methods, we identified that ATP-binding cassette transporter A1 (ABCA1) is an EVs protein marker for diagnosing AMD. Additionally, a validation set was constructed using the random forest method for verification.
RESULTS: The results of the study indicated that ABCA1 is a reliable biomarker for diagnosing AMD. The validation using the random forest method confirmed the robustness and reliability of ABCA1 as a diagnostic marker. This finding suggested that ABCA1 can serve as a new promising liquid biopsy-based marker for diagnosing macular degeneration.
CONCLUSION: The utilization of EVs protein chips, combined with machine learning methods, can effectively identify ABCA1 as a biomarker for the early diagnosis of AMD. This approach offers a promising new method for liquid biopsy diagnostics, potentially improving the clinical diagnosis and management of macular degeneration.

Keywords:  age-related macular degeneration; extracellular vesicles; liquid biopsy diagnostics; machine learning

DOI:  https://doi.org/10.24976/Discov.Med.202436191.217
J Cell Mol Med. 2024 Dec;28(24): e70285

Melatonin Reduces Mito-Inflammation in Ischaemic Hippocampal HT22 Cells and Modulates the cGAS-STING Cytosolic DNA Sensing Pathway and FGF21 Release.

Silvia Carloni, Maria Gemma Nasoni, Anna Casabianca, Chiara Orlandi, Loredana Capobianco, Giorgia Natalia Iaconisi, Liana Cerioni, Sabrina Burattini, Serena Benedetti, Russel J Reiter, Walter Balduini, Francesca Luchetti.

  Mitochondrial dysfunction is a key event in many pathological conditions, including neurodegenerative processes. When mitochondria are damaged, they release damage-associated molecular patterns (DAMPs) that activate mito-inflammation. The present study assessed mito-inflammation after in vitro oxygen-glucose deprivation as a representation of ischaemia, followed by reoxygenation (OGD/R) of HT22 cells and modulation of the inflammatory response by melatonin. We observed that melatonin prevented mitochondrial structural damage and dysfunction caused by OGD/R. Melatonin reduced oxidative damage and preserved the enzymatic activity for complexes I, III and IV, encoded by mitochondrial DNA, which were reduced by OGD/R. No effect was observed on complex II activity encoded by nuclear DNA. The release of mtDNA into the cytosol was also prevented with a consequent reduction of the cGAS-STING pathway and IFNβ and IL-6 production. Interestingly, melatonin also increased the early release of the fibroblast growth factor-21 (FGF-21), a mitokine secreted in response to mitochondrial stress. These data indicate that melatonin reduces mito-inflammation and modulates FGF-21 release, further highlighting the key role of this molecule in preserving mitochondrial integrity in OGD/R deprivation-type ischaemic brain injury.

Keywords:  FGF‐21; HT22; melatonin; mito‐inflammation; mtDNA; oxygen–glucose deprivation

DOI:  https://doi.org/10.1111/jcmm.70285
Alzheimers Dement. 2024 Dec 23.

Stabilization of mitochondria-associated endoplasmic reticulum membranes regulates Aβ generation in a three-dimensional neural model of Alzheimer's disease.

Jacob C Zellmer, Marina B Tarantino, Michelle Kim, Selene Lomoio, Masato Maesako, György Hajnóczky, Raja Bhattacharyya.

   INTRODUCTION: We previously demonstrated that regulating mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) affects axonal Aβ generation in a well-characterized three-dimensional (3D) neural Alzheimer's disease (AD) model. MAMs vary in thickness and length, impacting their functions. Here, we examined the effect of MAM thickness on Aβ in our 3D neural model of AD.
METHODS: We employed fluorescence resonance energy transfer (FRET) or fluorescence-based MAM stabilizers, electron microscopy, Aβ enzyme-linked immunosorbent assay (ELISA), and live-cell imaging with kymography to assess how stabilizing MAMs of different gap widths influence Aβ production and MAM axonal mobility.
RESULTS: Stabilizing tight MAMs (∼6 nm gap width) significantly increased Aβ levels, whereas basal (∼25 nm) and loose MAMs (∼40 nm) maintained or reduced Aβ levels, respectively. Tight MAMs reduced mitochondrial axonal velocity compared to basal MAMs, while loose MAMs showed severely reduced axonal distribution.
DISCUSSION: Our findings suggest that stabilizing MAMs of specific gap widths, particularly in axons, without complete destabilization could be an effective therapeutic strategy for AD.
HIGHLIGHTS: The stabilization of MAMs exacerbates or ameliorates Aβ generation from AD neurons in a MAM gap width-dependent manner. A specific stabilization threshold within the MAM gap width spectrum shifts the amyloidogenic process to non-amyloidogenic. Tight MAMs slow down mitochondrial axonal transport compared to lose MAMs offering a quantitative method for measuring MAM stabilization.

Keywords:  Alzheimer's disease; amyloid β; endoplasmic reticulum; mitochondria; mitochondria‐associated ER membranes; β‐amyloid precursor protein; β‐site APP cleaving enzyme

DOI:  https://doi.org/10.1002/alz.14417
PNAS Nexus. 2025 Jan;4(1): pgae556

Antibody-mediated clearance of an ER-resident aggregate that causes glaucoma.

Minh Thu Ma, Ahlam N Qerqez, Kamisha R Hill, Laura R Azouz, Hannah A Youngblood, Shannon E Hill, Yemo Ku, Donna M Peters, Jennifer A Maynard, Raquel L Lieberman.

  Recombinant antibodies are a promising class of therapeutics to treat protein misfolding associated with neurodegenerative diseases, and several antibodies that inhibit aggregation are approved or in clinical trials to treat Alzheimer's disease. Here, we developed antibodies targeting the aggregation-prone β-propeller olfactomedin (OLF) domain of myocilin, variants of which comprise the strongest genetic link to glaucoma and cause early onset vision loss for several million individuals worldwide. Mutant myocilin aggregates intracellularly in the endoplasmic reticulum (ER). Subsequent ER stress causes cytotoxicity that hastens dysregulation of intraocular pressure, the primary risk factor for most forms of glaucoma. Our antibody discovery campaign yielded two recombinant antibodies: anti-OLF1 recognizes a linear epitope, while anti-OLF2 is selective for natively folded OLF and inhibits aggregation in vitro. By binding OLF, these antibodies engage autophagy/lysosomal degradation to promote degradation of two pathogenic mutant myocilins. This work demonstrates the potential for therapeutic antibodies to disrupt ER-localized protein aggregates by altering the fate of folding intermediates. This approach could be translated as a precision medicine to treat myocilin-associated glaucoma with in situ antibody expression. More generally, the study supports the approach of enhancing lysosomal degradation to treat proteostasis decline in glaucoma and other diseases.

Keywords:  autophagy; molecular recognition; myocilin; protein misfolding; proteostasis

DOI:  https://doi.org/10.1093/pnasnexus/pgae556
Chembiochem. 2024 Dec 23. e202400887

NOVEL APPROACHES IN TARGETING MEMBRANE AND SECRETED PROTEINS FOR LYSOSOMAL DEGRADATION.

Mohamed Eldeeb, Grace Hohman, Michael Shahid.

  Protein degradation is pivotal for all biochemical aspects of cellular function. In mammalian cells, protein degradation is mediated mainly by the ubiquitin proteasome system (UPS) and the autophagic-lysosomal system (ALS). Over the last two decades, different types of targeted protein degradation approaches have been developed including proteolysis targeting chimeras (PROTACs) and lysosome targeting chimeras (LYTACs), which employ the UPS to degrade intracellular proteins and the ALS to degrade extracellular and membrane proteins respectively. Nevertheless, current targeted membrane protein degradation approaches face some inherent challenges including limited target protein degradation efficacy and cell type specific applicability. Herein, we highlight a recent development of novel targeted membrane protein degradation modalities that exhibit wide-applicability and high protein degradation efficiency. These novel membrane protein degraders hold tremendous promise as new pharmacological and biochemical tools in targeting membrane and secretory proteins for lysosomal degradation.

Keywords:  Lysosome; Protein degradation; Proteolysis; autophagy; membrane proteins

DOI:  https://doi.org/10.1002/cbic.202400887
Stem Cell Reports. 2024 Dec 10. pii: S2213-6711(24)00323-0. [Epub ahead of print] 102379

Engineering the 3D structure of organoids.

Samuel P Moss, Ezgi Bakirci, Adam W Feinberg.

  Organoids form through the sel f-organizing capabilities of stem cells to produce a variety of differentiated cell and tissue types. Most organoid models, however, are limited in terms of the structure and function of the tissues that form, in part because it is difficult to regulate the cell type, arrangement, and cell-cell/cell-matrix interactions within these systems. In this article, we will discuss the engineering approaches to generate more complex organoids with improved function and translational relevance, as well as their advantages and disadvantages. Additionally, we will explore how biofabrication strategies can manipulate the cell composition, 3D organization, and scale-up of organoids, thus improving their utility for disease modeling, drug screening, and regenerative medicine applications.

Keywords:  3D bioprinting; biofabrication; organoids; spheroids; stem cells; vascularization

DOI:  https://doi.org/10.1016/j.stemcr.2024.11.009
J Mol Neurosci. 2024 Dec 27. 75(1): 3

Identifying the Pathogenicity of a Novel NPRL3 Missense Mutation Using Personalized Cortical Organoid Model of Focal Cortical Dysplasia.

Rongrong Lu, Ying Xu, Hao Li, Man Xiong, Wenhao Zhou, Weijun Feng, Rui Zhao.

  Focal cortical dysplasia (FCD) II is a cortical malformation characterized by cortical architectural abnormalities, dysmorphic neurons, with or without balloon cells. Here, we systematically explored the pathophysiological role of the GATOR1 subunit NPRL3 variants including a novel mutation from iPSCs derived from one FCD II patient. Three FCD II children aged 0.5-7 years who underwent cerebral lesion resection in our hospital from March 2019 to October 2019 were included in this study. We generated patient-derived iPSCs and performed whole-exome sequencing to accurately identify somatic cells with mutations. The effect of the newly identified NPRL3 mutation found in one of our FCD II patients was evaluated using the personalized cortical organoid model and the NPRL3 knockout HEK293T cells. Whole-exome sequencing of iPSCs derived from FCD II patients revealed a novel NPRL3 C.767G > C (p.R256P) heterozygous mutation. Cortical organoids generated from iPSCs of FCD II patients were larger than control iPSCs, with increased number of p-S6+ cells and NeuN+ neurons. In NPRL3 knockout HEK293T cells, overexpression of NPRL3 together with NPRL2 protein is necessary to reduce p-S6 level upon amino acid starvation. The reduced binding between NPRL3 Arg256Pro and NPRL2 protein leads to downregulation of the relative total protein amount of both proteins in the cell. Our study describes a novel cortical organoid model generated from iPSCs of the FCD patients to investigate the underlying mechanism of NPRL3-related epilepsy. The mutation of NPRL3 Arg256Pro impaired the function of NPRL3 protein via affecting the binding with NPRL2 protein, which resulted in unstable protein monomer.

Keywords:  Focal cortical dysplasia; Human cortical organoids; Induced pluripotent stem cells; NPRL3 missense mutation

DOI:  https://doi.org/10.1007/s12031-024-02304-5
Cancer Sci. 2024 Dec 27.

Quantitative Live Imaging Reveals Phase Dependency of PDAC Patient-Derived Organoids on ERK and AMPK Activity.

Shoko Tsukamoto, Ye Huaze, Zhang Weisheng, Akihito Machinaga, Nobuyuki Kakiuchi, Seishi Ogawa, Hiroshi Seno, Shigeki Higashiyama, Michiyuki Matsuda, Toru Hiratsuka.

  Patient-derived organoids represent a novel platform to recapitulate the cancer cells in the patient tissue. While cancer heterogeneity has been extensively studied by a number of omics approaches, little is known about the spatiotemporal kinase activity dynamics. Here we applied a live imaging approach to organoids derived from 10 pancreatic ductal adenocarcinoma (PDAC) patients to comprehensively understand their heterogeneous growth potential and drug responses. By automated wide-area image acquisitions and analyses, the PDAC cells were non-selectively observed to evaluate their heterogeneous growth patterns. We monitored single-cell ERK and AMPK activities to relate cellular dynamics to molecular dynamics. Furthermore, we evaluated two anti-cancer drugs, a MEK inhibitor, PD0325901, and an autophagy inhibitor, hydroxychloroquine (HCQ), by our analysis platform. Our analyses revealed a phase-dependent regulation of PDAC organoid growth, where ERK activity is necessary for the early phase and AMPK activity is necessary for the late stage of organoid growth. Consistently, we found PD0325901 and HCQ target distinct organoid populations, revealing their combination is widely effective to the heterogeneous cancer cell population in a range of PDAC patient-derived organoid lines. Together, our live imaging quantitatively characterized the growth and drug sensitivity of human PDAC organoids at multiple levels: in single cells, single organoids, and individual patients. This study will pave the way for understanding the cancer heterogeneity and promote the development of new drugs that eradicate intractable cancer.

Keywords:  AMPK; ERK; heterogeneity; live imaging; pancreatic cancer

DOI:  https://doi.org/10.1111/cas.16439
Eur J Cell Biol. 2024 Dec 19. pii: S0171-9335(24)00087-6. [Epub ahead of print]104(1): 151470

Beyond consciousness: Ethical, legal, and social issues in human brain organoid research and application.

Masanori Kataoka, Takuya Niikawa, Naoya Nagaishi, Tsung-Ling Lee, Alexandre Erler, Julian Savulescu, Tsutomu Sawai.

  This study aims to provide a comprehensive review of the ethical, legal and social issues in human brain organoid research, with a view to different types of research and applications: in vitro research, transplantation into non-human animals, and biocomputing. Despite the academic and societal attention on the possibility that human brain organoids may be conscious, we have identified diverse issues in human brain organoid research and applications. To guide the complex terrain of human brain organoid research and applications, a multidisciplinary approach that integrates ethical, legal, and social perspectives is essential.

Keywords:  Biocomputing; Brain organoid; Chimera; ELSI; Ethics; Public engagement

DOI:  https://doi.org/10.1016/j.ejcb.2024.151470
Alzheimers Dement. 2024 Dec 23.

TMEM106B C-terminal fragments aggregate and drive neurodegenerative proteinopathy in transgenic Caenorhabditis elegans.

Ruben Riordan, Aleen Saxton, Marina Han, Pamela J McMillan, Rebecca L Kow, Nicole F Liachko, Brian C Kraemer.

   INTRODUCTION: Genetic variation in the lysosomal and transmembrane protein 106B (TMEM106B) modifies risk for several neurodegenerative disorders, especially frontotemporal lobar degeneration (FTLD). The C-terminal (CT) domain of TMEM106B occurs as fibrillar protein deposits in the brains of dementia patients.
METHODS: To determine the TMEM CT aggregation propensity and neurodegenerative potential, we generated transgenic Caenorhabditis elegans expressing the human TMEM CT fragment aggregating in FTLD cases.
RESULTS: Pan-neuronal expression of human TMEM CT in C. elegans causes severe neuronal dysfunction driving neurodegeneration. Cytosolic aggregation of TMEM CT proteins accompanied by behavioral dysfunction and neurodegeneration. Loss of pgrn-1 did not modify TMEM CT phenotypes suggesting TMEM CT aggregation occurs downstream of PGRN loss of function. The mechanistic drivers of TMEM106B proteinopathy appear distinct from known modifiers of tauopathy.
DISCUSSION: Our data demonstrate that TMEM CT aggregation can kill neurons. TMEM106B transgenic C.elegans provide a useful model for characterizing TMEM106B proteinopathy-mediated neurodegeneration in FTLD.
HIGHLIGHTS: Pan-neuronal expression of human TMEM106B C-terminal fragments (TMEM CT) in C. elegans neurons drives a suite of disease-related phenotypes useful for modeling the molecular and cellular features of TMEM106B neuropathology. TMEM CT expression results in extensive TMEM aggregation and accumulation of highly detergent insoluble protein species. TMEM CT expression causes moderate to severe neuronal dysfunction dependent on TMEM CT abundance as measured by stereotypical behavioral readouts. TMEM CT expression drives significant neurodegenerative changes. Dendra2 tagged TMEM exhibits similar properties to untagged TMEM allowing ready visualization of the protein. TMEM CT aggregates accumulate adjacent to but not within lysosomes. PGRN loss of function does not impact TMEM CT toxicity. Modifiers of tau and TDP-43 proteinopathies have little impact on TMEM CT-related neurodegenerative phenotypes.

Keywords:  TMEM106B; aging; dementia; frontotemporal lobar degeneration; neurodegeneration; progranulin; proteinopathy; tau

DOI:  https://doi.org/10.1002/alz.14468
Methods Mol Biol. 2025 ;2884 355-368

Decision Tree for Protein Biomarker Selection for Clinical Applications.

Katharina Waury.

  Discovery of novel protein biomarkers for clinical applications is an active research field across a manifold of diseases. Despite some successes and progress, the biomarker development pipeline still frequently ends in failure. Biomarker candidates that are discovered by appropriate technologies such as unbiased mass spectrometry cannot be validated or translated to immunoassays in many cases. Selection of strong disease biomarker candidates that further constitute suitable targets for antibody binding in immunoassays is thus important to allow routine clinical use. This essential selection step can be supported and rationalized using bioinformatics tools such as protein databases. Here, we present a workflow in the form of decision trees to computationally investigate biomarker candidates and their available affinity reagents in depth. This analysis can identify the most promising biomarker candidates for assay development, while minimal time and effort are required.

Keywords:  Antibodies; Bioinformatics; Immunoassays; Online databases; Protein biomarker

DOI:  https://doi.org/10.1007/978-1-0716-4298-6_21
J Neuroeng Rehabil. 2024 Dec 21. 21(1): 223

Free-living monitoring of ALS progression in upper limbs using wearable accelerometers.

Marcin Straczkiewicz, Katherine M Burke, Narghes Calcagno, Alan Premasiri, Fernando G Vieira, Jukka-Pekka Onnela, James D Berry.

BACKGROUND: Wearable technology offers objective and remote quantification of disease progression in neurological diseases such as amyotrophic lateral sclerosis (ALS). Large population studies are needed to determine generalization and reproducibility of findings from pilot studies.
METHODS: A large cohort of patients with ALS (N = 202) wore wearable accelerometers on their dominant and non-dominant wrists for a week every two to four weeks and self-entered the ALS Functional Rating Scale-Revised (ALSFRS-RSE) in similar time intervals. Wearable device data were processed to quantify digital biomarkers on four upper limb movements: flexion, extension, supination, and pronation using previously developed and validated open-source methodology. In this study, we determined the association between digital biomarkers and disease progression, studied the impact of study design in terms of required sensor wear-time and sensor position, and determined the impact of self-reported disease onset location on upper limb movements.
RESULTS: The main investigation considered data from a sensor placed on the non-dominant wrist. Participants with higher ALSFRS-RSE scores performed more frequent and faster upper limb movements compared to participants with more advanced disease status. Digital biomarkers exhibited statistically significant change over time while their rate of change was more profound compared to survey responses. Using data from the dominant wrist and changing data inclusion criteria did not alter our findings. ALS disease onset location significantly impacted use of upper limbs. Results presented here were comparable to an earlier study on twenty patients with ALS.
DISCUSSION: Digital health technologies provide sensitive and objective means to quantify ALS disease progression. Interpretable approaches, such as the one used in this paper, can improve patient evaluation and hasten therapeutic development.

DOI: https://doi.org/10.1186/s12984-024-01514-7
Biol Methods Protoc. 2024 ;9(1): bpae093

An efficient injection protocol for Drosophila larvae.

Sattar Soltani, Nhan Huynh, Kirst King-Jones.

  Intravenous injection provides a direct, rapid, and efficient route for delivering drugs or other substances, particularly for compounds with poor intestinal absorption or molecules (e.g. proteins) that are prone to structural changes and degradation within the digestive system. While Drosophila larvae represent a well-established genetic model for studying developmental and physiological pathways, as well as human diseases, their use in analyzing the molecular effects of substance exposure remains limited. In this study, we present a highly efficient injection method for Drosophila first- and second-instar larvae. Despite causing a slight developmental delay, this method achieves a high survival rate and offers a quick, easily adjustable protocol. The process requires 3-5 h to inject 150-300 larvae, depending on the microcapillary needle, microinjection system, and the compound being administered. As proof of concept, we compared the effects of injecting ferritin protein into Fer1HCH00451 mutant first instar larvae with those of dietary ferritin administration. Our results show that ferritin injection rescues Fer1HCH mutants, a result that cannot be achieved through dietary delivery. This approach is particularly valuable for the delivery of complex compounds in cases where oral administration is impaired or limited by the digestive system.

Keywords:  Drosophila larval drug delivery; drug administration; ferritin; ferritin injection; injection; larval injection

DOI:  https://doi.org/10.1093/biomethods/bpae093