bims-axbals 2024-11-17 papers

bims-axbals

Biomed News

on Axonal Biology and ALS

Issue of 2024‒11‒17
35 papers selected by
TJ Krzystek, ALS Therapy Development Institute

Modeling of TDP-43 proteinopathy by chronic oxidative stress identifies rapamycin as beneficial in ALS patient-derived 2D and 3D iPSC models.
Optimizing TDP-43 silencing with siRNA-loaded polymeric nanovectors in neuronal cells for therapeutic applications: balancing knockdown and function.
Imaging Mitochondrial Axonal Transport in Human Induced Pluripotent Stem Cell-Derived Neurons.
CK and LRRK2 Involvement in Neurodegenerative Diseases.
n-Butylidenephthalide recovered calcium homeostasis to ameliorate neurodegeneration of motor neurons derived from amyotrophic lateral sclerosis iPSCs.
HuD impairs neuromuscular junctions and induces apoptosis in human iPSC and Drosophila ALS models.
Gut microbiota immune cross-talk in amyotrophic lateral sclerosis.
New perspectives of the role of skeletal muscle derived extracellular vesicles in the pathogenesis of amyotrophic lateral sclerosis: the 'dying back' hypothesis.
The lemur tail kinase family in neuronal function and disfunction in neurodegenerative diseases.
Understanding Mitochondrial and Lysosomal Dynamics by Fluorescent Microscopy.
Generating iAstrocytes From Human Induced Pluripotent Stem Cells by Combining Low-Density Passaging of Neural Progenitor Cells and Transcription Factor NFIA Transdifferentiation.
ATP1A3 dysfunction causes motor hyperexcitability and afterhyperpolarization loss in a dystonia model.
Proteomic and functional comparison between human induced and embryonic stem cells.
Quantitative spinal cord imaging: Early ALS diagnosis and monitoring of disease progression.
[Current Status of Drug Development for Amyotrophic Lateral Sclerosis].
Amyotrophic lateral sclerosis represents corticomotoneuronal system failure.
Cell type-specific gene therapy confers protection against motor neuron disease caused by a TFG variant.
Macrophage LRRK2 hyperactivity impairs autophagy and induces Paneth cell dysfunction.
Microglia contribute to the production of the amyloidogenic ABri peptide in familial British dementia.
LRRK2 and RAB8A regulate cell death after lysosomal damage in macrophages through cholesterol-related pathways.
Calcium signaling from damaged lysosomes induces cytoprotective stress granules.
Gastrostomy in Amyotrophic Lateral Sclerosis: Timing Enhances Survival.
Live-Cell Imaging of mRNA Using a Pepper RNA Tag.
Short Peptides Protect Fibroblast-Derived Induced Neurons from Age-Related Changes.
Diversity of human skin three-dimensional organotypic cultures.
Pathogenic LRRK2 mutations cause loss of primary cilia and Neurturin in striatal parvalbumin interneurons.
Alternative production of pro-death Bax∆2 protein via ribosomal frameshift in Alzheimer's disease.
Revealing single-neuron and network-activity interaction by combining high-density microelectrode array and optogenetics.
GM1 Oligosaccharide Ameliorates Rett Syndrome Phenotypes In Vitro and In Vivo via Trk Receptor Activation.
Single-cell transcriptomics reveals the molecular basis of human iPS cell differentiation into ectodermal ocular lineages.
Protective effect of zinc against A2E-induced toxicity in ARPE-19 cells: Possible involvement of lysosomal acidification.
Rev or restrain: Mechanisms of human-specific synaptic neoteny.
Concurrent Profiling of Localized Transcriptome and RNA Dynamics in Neurons by Spatial SLAMseq.
FMRP regulates MFF translation to locally direct mitochondrial fission in neurons.
Modulation of SNARE-dependent exocytosis in astrocytes improves neuropathology in Huntington's disease.

Exp Neurol. 2024 Nov 12. pii: S0014-4886(24)00383-2. [Epub ahead of print]383 115057

Modeling of TDP-43 proteinopathy by chronic oxidative stress identifies rapamycin as beneficial in ALS patient-derived 2D and 3D iPSC models.

Valeria Casiraghi, Marta Nice Sorce, Serena Santangelo, Sabrina Invernizzi, Patrizia Bossolasco, Chiara Lattuada, Cristina Battaglia, Marco Venturin, Vincenzo Silani, Claudia Colombrita, Antonia Ratti.

  Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterized neuropathologically by TDP-43 proteinopathy with loss of TDP-43 nuclear splicing activity and formation of cytoplasmic TDP-43 aggregates. The lack of suitable experimental models of TDP-43 proteinopathy has hampered the discovery of effective therapies. We already showed that chronic and mild oxidative insult by sodium arsenite (ARS) triggered TDP-43 cytoplasmic aggregation and stress granules (SGs) formation in ALS patient-derived fibroblasts and motor neurons differentiated from induced pluripotent stem cells (iPSC-MNs). However, whether this insult induces a reduction of TDP-43 splicing activity in the nucleus, thus recapitulating both gain and loss of function pathomechanisms, still remains to be determined. In this study we first showed that chronic ARS in human neuroblastoma cells triggered TDP-43 cytoplasmic mislocalization, SGs formation and defective splicing of TDP-43 target genes UNC13A and POLDIP3 as functional readouts of TDP-43 proteinopathy. Additionally, a dysregulation of autophagy and senescence markers was observed in this condition. In a preliminary drug screening approach with autophagy-promoting drugs, namely rapamycin, lithium carbonate and metformin, only rapamycin prevented ARS-induced loss of TDP-43 splicing activity. We then demonstrated that, in addition to TDP-43 cytoplasmic aggregation, chronic ARS triggered TDP-43 loss of splicing activity also in ALS patient-derived primary fibroblasts and iPSC-MNs and that rapamycin was beneficial to reduce these TDP-43 pathological features. By switching to a neuro-glial 3D in vitro model, we observed that treatment of ALS iPSC-brain organoids with chronic ARS also induced a defective TDP-43 splicing activity which was prevented by rapamycin. Collectively, we established different human cell models of TDP-43 proteinopathy which recapitulate TDP-43 gain and loss of function, prevented by rapamycin administration. Human neuroblastoma cells and patient-derived fibroblasts and 2D- and 3D-iPSC models exposed to chronic oxidative stress represent therefore suitable in vitro platforms for future drug screening approaches in ALS.

Keywords:  ALS; Rapamycin; TDP-43; iPSC-derived brain organoids; iPSC-derived motor neurons

DOI:  https://doi.org/10.1016/j.expneurol.2024.115057
Nanoscale. 2024 Nov 14.

Optimizing TDP-43 silencing with siRNA-loaded polymeric nanovectors in neuronal cells for therapeutic applications: balancing knockdown and function.

Annamaria Russo, Gabriele Maiorano, Barbara Cortese, Stefania D'Amone, Alessandra Invidia, Angelo Quattrini, Alessandro Romano, Giuseppe Gigli, Ilaria E Palamà.

TAR DNA-binding protein 43 (TDP-43) is a ubiquitously expressed DNA/RNA binding protein critical for regulating gene expression, including transcription, splicing, mRNA stability, and protein translation. Aggregation of pathological TDP-43 proteins in the cytoplasm of neurons and glial cells appears to be a common feature of amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases such as frontotemporal dementia (FTD), contributing to motor neuron degeneration and clinical symptoms. Downregulation of TDP-43 expression to prevent or reduce the formation of pathological aggregates is a potential therapeutic approach for treating TDP-43-related diseases. However, therapeutic strategies to reduce TDP-43 aggregation face significant challenges, as the downregulation of TDP-43 must balance the need to maintain its normal functions, which are essential for RNA metabolism and cellular homeostasis. In this study, we developed novel polymeric nanovectors for the delivery of TDP-43 siRNAs in neuronal cells. These nanovectors were designed to provide adequate TDP-43 silencing to achieve the desired functional reduction of TDP-43 levels, thereby optimizing its impact on cellular functions. Our results demonstrate that the polymeric nanovector formulations effectively reduced TDP-43 mRNA and protein levels to an extent comparable to those observed with traditional lipid-based systems. Concurrently, the polymeric nanovectors exhibited an enhanced capacity to reduce stress granules (SG) formation and facilitate TDP-43-containing SG disassembly, while preserving its essential cellular functions. This study provides the first evidence that polymeric nanovectors may be a valuable tool for developing therapeutic strategies to treat TDP-43 protein diseases, such as ALS and FTD, by directly silencing TDP-43 to reduce its aggregation.

DOI: https://doi.org/10.1039/d4nr03159h
Methods Mol Biol. 2025 ;2878 201-209

Imaging Mitochondrial Axonal Transport in Human Induced Pluripotent Stem Cell-Derived Neurons.

Carla Lopes.

  Neuronal mitochondria are essential organelles to maintain synaptic activity due to the high calcium buffering capacity and ATP production. In neurons, mitochondria transport occurs along the microtubules mediated by motor proteins, kinesins and dynein, to drive mitochondria toward the synapses. Disruption of axonal transport is an early pathogenic event in neurodegenerative disorders and growing evidence supports that it may precede neurodegeneration. Here, we describe a method to label mitochondria with fluorescent proteins to monitor their movement along the axons in hiPSC-derived medium spiny neuron-like cells. We also included a detailed protocol for differentiation of hiPSC that produces electrophysiologically mature GABAergic striatal neurons with low amount of glial population.

Keywords:  Kymographs; Medium spiny neurons; Mitochondria; Transport; iPSC

DOI:  https://doi.org/10.1007/978-1-0716-4264-1_10
Int J Mol Sci. 2024 Oct 30. pii: 11661. [Epub ahead of print]25(21):

CK and LRRK2 Involvement in Neurodegenerative Diseases.

Valentina Bova, Deborah Mannino, Anna Paola Capra, Marika Lanza, Nicoletta Palermo, Alessia Filippone, Emanuela Esposito.

  Neurodegenerative diseases (NDDs) are currently the most widespread neuronal pathologies in the world. Among these, the most widespread are Alzheimer's disease (AD), dementia, Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD)-all characterized by a progressive loss of neurons in specific regions of the brain leading to varied clinical symptoms. At the basis of neurodegenerative diseases, an emerging role is played by genetic mutations in the leucine-rich repeat kinase 2 (LRRK2) gene that cause increased LRRK2 activity with consequent alteration of neuronal autophagy pathways. LRRK2 kinase activity requires GTPase activity which functions independently of kinase activity and is required for neurotoxicity and to potentiate neuronal death. Important in the neurodegeneration process is the upregulation of casein kinase (CK), which causes the alteration of the AMPK pathway by enhancing the phosphorylation of α-synuclein and huntingtin proteins, known to be involved in PD and HD, and increasing the accumulation of the amyloid-β protein (Aβ) for AD. Recent research has identified CK of the kinases upstream of LRRK2 as a regulator of the stability of the LRRK2 protein. Based on this evidence, this review aims to understand the direct involvement of individual kinases in NDDs and how their crosstalk may impact the pathogenesis and early onset of neurodegenerative diseases.

Keywords:  casein kinases; degradative pathways; leucine riche-repeat kinase; neurodegeneration

DOI:  https://doi.org/10.3390/ijms252111661
PLoS One. 2024 ;19(11): e0311573

n-Butylidenephthalide recovered calcium homeostasis to ameliorate neurodegeneration of motor neurons derived from amyotrophic lateral sclerosis iPSCs.

Yu-Chen Deng, Jen-Wei Liu, Hsiao-Chien Ting, Tzu-Chen Kuo, Chia-Hung Chiang, En-Yi Lin, Horng-Jyh Harn, Shinn-Zong Lin, Chia-Yu Chang, Tzyy-Wen Chiou.

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease that causes muscle atrophy and primarily targets motor neurons (MNs). Approximately 20% of familial ALS cases are caused by gain-of-function mutations in superoxide dismutase 1 (SOD1), leading to MN degeneration and ion channel dysfunction. Previous studies have shown that n-Butylidenephthalide (BP) delays disease progression and prolongs survival in animal models of ALS. However, no studies have been conducted on models from human sources. Herein, we examined the protective efficacy of BP on MNs derived from induced pluripotent stem cells (iPSCs) of an ALS patient harboring the SOD1G85R mutation as well as on those derived from genetically corrected iPSCs (SOD1G85G). Our results demonstrated that the motor neurons differentiated from iPSC with SOD1G85R mutation exhibited characteristics of neuron degeneration (as indicated by the reduction of neurofilament expression) and ion channel dysfunction (in response to potassium chloride (KCl) and L-glutamate stimulation), in contrast to those derived from the gene corrected iPSC (SOD1G85G). Meanwhile, BP treatment effectively restored calcium ion channel function by reducing the expression of glutamate receptors including glutamate ionotropic receptor AMPA type subunit 3 (GluR3) and glutamate ionotropic receptor NMDA type subunit 1 (NMDAR1). Additionally, BP treatment activated autophagic pathway to attenuate neuron degeneration. Overall, this study supports the therapeutic effects of BP on ALS patient-derived neuron cells, and suggests that BP may be a promising candidate for future drug development.

DOI: https://doi.org/10.1371/journal.pone.0311573
Nat Commun. 2024 Nov 07. 15(1): 9618

HuD impairs neuromuscular junctions and induces apoptosis in human iPSC and Drosophila ALS models.

Beatrice Silvestri, Michela Mochi, Darilang Mawrie, Valeria de Turris, Alessio Colantoni, Beatrice Borhy, Margherita Medici, Eric Nathaniel Anderson, Maria Giovanna Garone, Christopher Patrick Zammerilla, Marco Simula, Monica Ballarino, Udai Bhan Pandey, Alessandro Rosa.

Defects at the neuromuscular junction (NMJ) are among the earliest hallmarks of amyotrophic lateral sclerosis (ALS). According to the "dying-back" hypothesis, NMJ disruption not only precedes but also triggers the subsequent degeneration of motoneurons in both sporadic (sALS) and familial (fALS) ALS. Using human induced pluripotent stem cells (iPSCs), we show that the RNA-binding protein HuD (ELAVL4) contributes to NMJ defects and apoptosis in FUS-ALS. HuD overexpression mimics the severe FUSP525L mutation, while its knockdown rescues the FUSP525L phenotypes. In Drosophila, neuronal overexpression of the HuD ortholog, elav, induces motor dysfunction, and its knockdown improves motor function in a FUS-ALS model. Finally, we report increased HuD levels upon oxidative stress in human motoneurons and in sALS patients with an oxidative stress signature. Based on these findings, we propose that HuD plays a role downstream of FUS mutations in fALS and in sALS related to oxidative stress.

DOI: https://doi.org/10.1038/s41467-024-54004-8
Neurotherapeutics. 2024 Oct;pii: S1878-7479(24)00156-9. [Epub ahead of print]21(6): e00469

Gut microbiota immune cross-talk in amyotrophic lateral sclerosis.

Megha Kaul, Debanjan Mukherjee, Howard L Weiner, Laura M Cox.

  Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of motor neurons. While there has been significant progress in defining the genetic contributions to ALS, greater than 90 % of cases are sporadic, which suggests an environmental component. The gut microbiota is altered in ALS and is an ecological factor that contributes to disease by modulating immunologic, metabolic, and neuronal signaling. Depleting the microbiome worsens disease in the SOD1 ALS animal model, while it ameliorates disease in the C9orf72 model of ALS, indicating critical subtype-specific interactions. Furthermore, administering beneficial microbiota or microbial metabolites can slow disease progression in animal models. This review discusses the current state of microbiome research in ALS, including interactions with different ALS subtypes, evidence in animal models and human studies, key immunologic and metabolomic mediators, and a path toward microbiome-based therapies for ALS.

Keywords:  Amyotrophic lateral sclerosis; Immunology; Metabolites; Microbiome; Microglia

DOI:  https://doi.org/10.1016/j.neurot.2024.e00469
J Extracell Biol. 2024 Nov;3(11): e70019

New perspectives of the role of skeletal muscle derived extracellular vesicles in the pathogenesis of amyotrophic lateral sclerosis: the 'dying back' hypothesis.

Carolina Sbarigia, Sophie Rome, Luciana Dini, Stefano Tacconi.

  Amyotrophic lateral sclerosis (ALS), is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord, and is characterized by muscle weakness, paralysis and ultimately, respiratory failure. The exact causes of ALS are not understood, though it is believed to combine genetic and environmental factors. Until now, it was admitted that motor neurons (MN) in the brain and spinal cord degenerate, leading to muscle weakness and paralysis. However, as ALS symptoms typically begin with muscle weakness or stiffness, a new hypothesis has recently emerged to explain the development of the pathology, that is, the 'dying back hypothesis', suggesting that this degeneration starts at the connections between MN and muscles, resulting in the loss of muscle function. Over time, this damage extends along the length of the MN, ultimately affecting their cell bodies in the spinal cord and brain. While the dying back hypothesis provides a potential framework for understanding the progression of ALS, the exact mechanisms underlying the disease remain complex and not fully understood. In this review, we are positioning the role of extracellular vesicles as new actors in ALS development.

Keywords:  amyotrophic lateral sclerosis; biomarkers; extracellular vesicles; neuromuscular junctions; skeletal muscle

DOI:  https://doi.org/10.1002/jex2.70019
Cell Mol Life Sci. 2024 Nov 09. 81(1): 447

The lemur tail kinase family in neuronal function and disfunction in neurodegenerative diseases.

Angelique Larose, Christopher C J Miller, Gábor M Mórotz.

  The complex neuronal architecture and the long distance of synapses from the cell body require precisely orchestrated axonal and dendritic transport processes to support key neuronal functions including synaptic signalling, learning and memory formation. Protein phosphorylation is a major regulator of both intracellular transport and synaptic functions. Some kinases and phosphatases such as cyclin dependent kinase-5 (cdk5)/p35, glycogen synthase kinase-3β (GSK3β) and protein phosphatase-1 (PP1) are strongly involved in these processes. A primary pathological hallmark of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis/frontotemporal dementia, is synaptic degeneration together with disrupted intracellular transport. One attractive possibility is that alterations to key kinases and phosphatases may underlie both synaptic and axonal transport damages. The brain enriched lemur tail kinases (LMTKs, formerly known as lemur tyrosine kinases) are involved in intracellular transport and synaptic functions, and are also centrally placed in cdk5/p35, GSK3β and PP1 signalling pathways. Loss of LMTKs is documented in major neurodegenerative diseases and thus can contribute to pathological defects in these disorders. However, whilst function of their signalling partners became clearer in modulating both synaptic signalling and axonal transport progress has only recently been made around LMTKs. In this review, we describe this progress with a special focus on intracellular transport, synaptic functions and neurodegenerative diseases.

Keywords:  Alzheimer’s disease; Axonal transport; Cyclin dependent kinase-5/p35; Endosome; Glycogen synthase kinase-3 beta; Lemur tail kinase

DOI:  https://doi.org/10.1007/s00018-024-05480-0
Methods Mol Biol. 2025 ;2878 211-221

Understanding Mitochondrial and Lysosomal Dynamics by Fluorescent Microscopy.

Pedro A Dionísio, Vilma A Sardão, Nuno Raimundo.

  Live cell imaging is a robust method to visualize dynamic cellular structures, especially organelles with network-like structures such as mitochondria. In this regard, mitochondrial dynamics, namely mitochondrial fission and fusion, are highly dynamic processes that regulate mitochondrial size and morphology depending on a plethora of cellular cues. Likewise, lysosome size and distribution may hint at their function and state.Here, we describe how to perform live cell confocal imaging using commercially available organelle dyes (MitoTracker, LysoTracker), followed by either 2D or 3D analyses of mitochondrial morphology/network connectivity and lysosomal morphology using the freely available Mitochondria Analyzer plugin for ImageJ/Fiji.

Keywords:  Cell imaging; Fluorescent probes; LysoTracker; Lysosomes; Microscopy; MitoTracker; Mitochondria; Mitochondrial dynamics

DOI:  https://doi.org/10.1007/978-1-0716-4264-1_11
Curr Protoc. 2024 Nov;4(11): e70049

Generating iAstrocytes From Human Induced Pluripotent Stem Cells by Combining Low-Density Passaging of Neural Progenitor Cells and Transcription Factor NFIA Transdifferentiation.

Patrick Bosco, Ugur Akcan, Damian Williams, Heather M Buchanan, Dritan Agalliu, Andrew A Sproul.

  Astrocytes are key regulators of central nervous system (CNS) homeostasis, and their dysfunction is implicated in neurological and neurodegenerative disorders. Here, we describe a two-step protocol to generate astrocytes from human induced pluripotent stem cells (hiPSCs) using a bankable neural progenitor cell (NPC) intermediate, followed by low-density passaging and overexpression of the gliogenic transcription factor NFIA. A bankable NPC intermediate allows for facile differentiation into both purified neuronal and astrocyte cell types in parallel from the same genetic background, depending on the experimental needs. This article presents a protocol to generate NPCs from hiPSCs, which are then differentiated into hiPSC-derived astrocytes, termed iAstrocytes. The resulting iAstrocytes express key markers of astrocyte identity at transcript and protein levels by bulk RNA-Seq and immunocytochemistry, respectively. Additionally, they respond to the inflammatory stimuli poly(I:C) and generate waves of calcium activity in response to either physical activity or the addition of ATP. Our approach offers a simple and robust method to generate and characterize human astrocytes, which can be used to model human disease affecting this cell type. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Differentiation of hiPSCs to NPCs Basic Protocol 2: Differentiation of NPCs into iAstrocytes Support Protocol 1: Molecular validation of iAstrocytes Support Protocol 2: Calcium imaging-based validation of iAstrocyte function Support Protocol 3: Differentiation of NPCs into neurons.

Keywords:  astrocyte; doxycycline inducible tet‐O system; human pluripotent stem cells; neural progenitor cells; transcription factor NFIA

DOI:  https://doi.org/10.1002/cpz1.70049
Brain. 2024 Nov 13. pii: awae373. [Epub ahead of print]

ATP1A3 dysfunction causes motor hyperexcitability and afterhyperpolarization loss in a dystonia model.

Evgeny E Akkuratov, Francesca Sorrell, Laurence Picton, Vasco C Sousa, Martin Paucar, Daniel Jans, Lill-Britt Svensson, Maria Lindskog, Nicolas Fritz, Thomas Liebmann, Keith T Sillar, Hendrik Rosewich, Per Svenningsson, Hjalmar Brismar, Gareth B Miles, Anita Aperia.

  Mutations in the gene encoding the alpha3 Na+/K+-ATPase isoform (ATP1A3) lead to movement disorders that manifest with dystonia, a common neurological symptom with many different origins, but for which the underlying molecular mechanisms remain poorly understood. We have generated an ATP1A3 mutant mouse that displays motor impairments and a hyperexcitable motor phenotype compatible with dystonia. We show that neurons harboring this mutation are compromised in their ability to extrude raised levels of intracellular sodium, highlighting a profound deficit in neuronal sodium homeostasis. We show that the spinal motor network in ATP1A3 mutant mice has a reduced responsiveness to activity-dependent rises in intracellular sodium and that this is accompanied by loss of the Na+/K+-ATPase-mediated afterhyperpolarization in motor neurons. Taken together, our data support that the alpha3 Na+/K+-ATPase is important for cellular and spinal motor network homeostasis. These insights suggest that it may be useful to consider ways to compensate for this loss of a critical afterhyperpolarization-dependent control of neuronal excitability when developing future therapies for dystonia.

Keywords:  ATP1A3 gene; Na+/K+-ATPase; motor control; rapid-onset dystonia-parkinsonism; spinal cord

DOI:  https://doi.org/10.1093/brain/awae373
Elife. 2024 Nov 14. pii: RP92025. [Epub ahead of print]13

Proteomic and functional comparison between human induced and embryonic stem cells.

Alejandro J Brenes, Eva Griesser, Linda V Sinclair, Lindsay Davidson, Alan R Prescott, Francois Singh, Elizabeth K J Hogg, Carmen Espejo-Serrano, Hao Jiang, Harunori Yoshikawa, Melpomeni Platani, Jason R Swedlow, Greg M Findlay, Doreen A Cantrell, Angus I Lamond.

  Human induced pluripotent stem cells (hiPSCs) have great potential to be used as alternatives to embryonic stem cells (hESCs) in regenerative medicine and disease modelling. In this study, we characterise the proteomes of multiple hiPSC and hESC lines derived from independent donors and find that while they express a near-identical set of proteins, they show consistent quantitative differences in the abundance of a subset of proteins. hiPSCs have increased total protein content, while maintaining a comparable cell cycle profile to hESCs, with increased abundance of cytoplasmic and mitochondrial proteins required to sustain high growth rates, including nutrient transporters and metabolic proteins. Prominent changes detected in proteins involved in mitochondrial metabolism correlated with enhanced mitochondrial potential, shown using high-resolution respirometry. hiPSCs also produced higher levels of secreted proteins, including growth factors and proteins involved in the inhibition of the immune system. The data indicate that reprogramming of fibroblasts to hiPSCs produces important differences in cytoplasmic and mitochondrial proteins compared to hESCs, with consequences affecting growth and metabolism. This study improves our understanding of the molecular differences between hiPSCs and hESCs, with implications for potential risks and benefits for their use in future disease modelling and therapeutic applications.

Keywords:  biochemistry; chemical biology; hESC; human; iPSC; mass spectrometry; protein content; proteomics; regenerative medicine; stem cell; stem cells

DOI:  https://doi.org/10.7554/eLife.92025
Rev Neurol (Paris). 2024 Nov 14. pii: S0035-3787(24)00657-X. [Epub ahead of print]

Quantitative spinal cord imaging: Early ALS diagnosis and monitoring of disease progression.

M Khamaysa, M El Mendili, V Marchand, G Querin, P-F Pradat.

  Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of motor neurons in the cortex, brainstem, and spinal cord. This degeneration leads to muscular weakness, progressively impairing motor functions and ultimately resulting in respiratory failure. The clinical, genetic, and pathological heterogeneity of ALS, combined with the absence of reliable biomarkers, significantly challenge the efficacy of therapeutic trials. Despite these hurdles, neuroimaging, and particularly spinal cord imaging, has emerged as a promising tool. It provides insights into the involvement of both upper and lower motor neurons. Quantitative spinal imaging has the potential to facilitate early diagnosis, enable accurate monitoring of disease progression, and refine the design of clinical trials. In this review, we explore the utility of spinal cord imaging within the broader context of developing spinal imaging biomarkers in ALS. We focus on a both diagnostic and prognostic biomarker in ALS, highlighting its pivotal role in elucidating the disease's underlying pathology. We also discuss the existing limitations and future avenues for research, aiming to bridge the translational gap between academic research and its application in clinical practice and therapeutic trials.

Keywords:  Amyotrophic lateral sclerosis (ALS); Biomarkers; MRI; Neuroimaging; Quantitative spinal Imaging

DOI:  https://doi.org/10.1016/j.neurol.2024.10.005
Brain Nerve. 2024 Nov;76(11): 1241-1249

[Current Status of Drug Development for Amyotrophic Lateral Sclerosis].

Yohei Iguchi, Masahisa Katsuno.

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal disease of motor neuron. Although riluzole and edaravone have been approved for the treatment of ALS, it remains a lethal disease that causes rapid motor impairment, and there is an urgent need to develop more effective treatments. Advances in understanding the pathomechanisms of ALS, efficient clinical trial design, and research support programs have led to many clinical trials for ALS both domestically and internationally.

DOI: https://doi.org/10.11477/mf.1416202766
Muscle Nerve. 2024 Nov 07.

Amyotrophic lateral sclerosis represents corticomotoneuronal system failure.

Andrew Eisen, Steve Vucic, Matthew C Kiernan.

  Several decades have passed since the anterograde corticomotoneuronal hypothesis for amyotrophic lateral sclerosis (ALS) was proposed. The intervening years have witnessed its emergent support based on anatomical, pathological, physiological, neuroimaging, and molecular biological studies. The evolution of an extensive corticomotoneuronal system appears restricted to the human species, with ALS representing a uniquely human disease. While some, very select non-human primates have limited corticomotoneuronal projections, these tend to be absent in all other animals. From a general perspective, the early clinical features of ALS may be considered to reflect failure of the corticomotoneuronal system. The characteristic loss of skilled motor dexterity involving the limbs, and speech impairment through progressive bulbar dysfunction specifically involve those motor units having the strongest corticomotoneuronal projections. A similar explanation likely underlies the unique "split phenotypes" that have now been well characterized in ALS. Large Betz cells and other pyramidal corticomotoneuronal projecting neurons, with their extensive dendritic arborization, are particularly vulnerable to the elements of the ALS exposome such as aging, environmental stress and lifestyle changes. Progressive failure of the proteosome impairs nucleocytoplasmic shuffling and induces toxic but soluble TDP-43 to aggregate in corticomotoneurons. Betz cell failure is further accentuated through dysfunction of its profuse dendritic arborizations. Clarification of system specific genomes and neural networks will likely promote the initiation of precision medicine approaches directed to support the key structure that underlies the neurological manifestations of ALS, the corticomotoneuronal system.

Keywords:  Betz cell; TDP‐43; amyotrophic lateral sclerosis; corticofugal excitotoxicity; corticomotoneuron

DOI:  https://doi.org/10.1002/mus.28290
Proc Natl Acad Sci U S A. 2024 Nov 19. 121(47): e2410996121

Cell type-specific gene therapy confers protection against motor neuron disease caused by a TFG variant.

Molly M Lettman, Caitlin A Mendina, Emma Burkard, James R Alvin, Yunyun Zhu, Joshua J Coon, Anjon Audhya.

  Inherited forms of motor neuron disease (MND), including hereditary spastic paraplegias (HSP), are associated with the death or dysfunction of nerve cells that control skeletal muscle activity. However, in some cases, the impacts of genetic variants underlying MND act in a non-cell autonomous manner, instead affecting the function of other cell types necessary for neuronal maintenance. Pathological mutations in TFG, which have been implicated in HSP, lead to axonopathy within the corticospinal tract, but it remains unclear whether this problem arises due to perturbations within neurons or supporting neuroglia. To address this question, we leveraged a rat model harboring the recessive TFG p.R106C mutation (mRATBN7.2, g.11:43897639C>T, c.316C>T), which recapitulates multiple phenotypes associated with HSP in humans, including progressive motor deficits, leg spasticity, and indications of an inflammatory response within the motor cortex. In particular, we took advantage of cell type-specific gene therapies to demonstrate that the reintroduction of wild-type TFG into synapsin 1-positive neurons provides robust protection against MND, whereas its expression in GFAP-positive glial cells provides no significant improvement in quantitative measures of gait, despite a dramatic reduction in the presence of reactive astrocytes throughout the brain. These data strongly suggest that therapeutic approaches targeting neurons should be pursued in cases of TFG-HSP, with our animal model offering a unique platform for preclinical assessment.

Keywords:  SYN1; neurodegeneration; neuroinflammation; spastic paraparesis

DOI:  https://doi.org/10.1073/pnas.2410996121
Sci Immunol. 2024 Nov 08. 9(101): eadi7907

Macrophage LRRK2 hyperactivity impairs autophagy and induces Paneth cell dysfunction.

Shengxiang Sun, Miki Hodel, Xiang Wang, Javier De Vicente, Talin Haritunians, Anketse Debebe, Chen-Ting Hung, Changqing Ma, Atika Malique, Hoang N Nguyen, Maayan Agam, Michael T Maloney, Marisa S Goo, Jillian H Kluss, Richa Mishra, Jennifer Frein, Amanda Foster, Samuel Ballentine, Uday Pandey, Justin Kern, Shaohong Yang, Emebet Mengesha, Iyshwarya Balasubramanian, Annie Arguello, Anthony A Estrada, Nan Gao, Inga Peter, Dermot P B McGovern, Anastasia G Henry, Thaddeus S Stappenbeck, Ta-Chiang Liu.

LRRK2 polymorphisms (G2019S/N2081D) that increase susceptibility to Parkinson's disease and Crohn's disease (CD) lead to LRRK2 kinase hyperactivity and suppress autophagy. This connection suggests that LRRK2 kinase inhibition, a therapeutic strategy being explored for Parkinson's disease, may also benefit patients with CD. Paneth cell homeostasis is tightly regulated by autophagy, and their dysfunction is a precursor to gut inflammation in CD. Here, we found that patients with CD and mice carrying hyperactive LRRK2 polymorphisms developed Paneth cell dysfunction. We also found that LRRK2 kinase can be activated in the context of interactions between genes (genetic autophagy deficiency) and the environment (cigarette smoking). Unexpectedly, lamina propria immune cells were the main intestinal cell types that express LRRK2, instead of Paneth cells as previously suggested. We showed that LRRK2-mediated pro-inflammatory cytokine release from phagocytes impaired Paneth cell function, which was rescued by LRRK2 kinase inhibition through activation of autophagy. Together, these data suggest that LRRK2 kinase inhibitors maintain Paneth cell homeostasis by restoring autophagy and may represent a therapeutic strategy for CD.

DOI: https://doi.org/10.1126/sciimmunol.adi7907
Acta Neuropathol. 2024 Nov 15. 148(1): 65

Microglia contribute to the production of the amyloidogenic ABri peptide in familial British dementia.

Charles Arber, Jackie M Casey, Samuel Crawford, Naiomi Rambarack, Umran Yaman, Sarah Wiethoff, Emma Augustin, Thomas M Piers, Matthew Price, Agueda Rostagno, Jorge Ghiso, Patrick A Lewis, Tamas Revesz, John Hardy, Jennifer M Pocock, Henry Houlden, Jonathan M Schott, Dervis A Salih, Tammaryn Lashley, Selina Wray.

  Mutations in ITM2B cause familial British, Danish, Chinese, and Korean dementias. In familial British dementia (FBD), a mutation in the stop codon of the ITM2B gene (also known as BRI2) causes a C-terminal cleavage fragment of the ITM2B/BRI2 protein to be extended by 11 amino acids. This fragment, termed amyloid-Bri (ABri), is highly insoluble and forms extracellular plaques in the brain. ABri plaques are accompanied by tau pathology, neuronal cell death and progressive dementia, with striking parallels to the aetiology and pathogenesis of Alzheimer's disease. The molecular mechanisms underpinning FBD are ill-defined. Using patient-derived induced pluripotent stem cells, we show that expression of ITM2B/BRI2 is 34-fold higher in microglia than neurons and 15-fold higher in microglia compared with astrocytes. This cell-specific enrichment is supported by expression data from both mouse and human brain tissue. ITM2B/BRI2 protein levels are higher in iPSC-microglia compared with neurons and astrocytes. The ABri peptide was detected in patient iPSC-derived microglial lysates and conditioned media but was undetectable in patient-derived neurons and control microglia. The pathological examination of post-mortem tissue supports the presence of ABri in microglia that are in proximity to pre-amyloid deposits. Finally, gene co-expression analysis supports a role for ITM2B/BRI2 in disease-associated microglial responses. These data demonstrate that microglia are major contributors to the production of amyloid forming peptides in FBD, potentially acting as instigators of neurodegeneration. Additionally, these data also suggest ITM2B/BRI2 may be part of a microglial response to disease, motivating further investigations of its role in microglial activation. These data have implications for our understanding of the role of microglia and the innate immune response in the pathogenesis of FBD and other neurodegenerative dementias including Alzheimer's disease.

Keywords:  Alzheimer’s disease; Amyloid; Dementia; Familial British dementia; Microglia; iPSC

DOI:  https://doi.org/10.1007/s00401-024-02820-z
Neurobiol Dis. 2024 Nov 07. pii: S0969-9961(24)00330-9. [Epub ahead of print]202 106728

LRRK2 and RAB8A regulate cell death after lysosomal damage in macrophages through cholesterol-related pathways.

Josefine Fussing Tengberg, Francesco Russo, Tau Benned-Jensen, Jacob Nielsen.

  Activating mutations in Leucine Rich Repeat Kinase 2 (LRRK2) are among the most common genetic causes of Parkinson's disease (PD). The mechanistic path from LRRK2 mutations to PD is not established, but several lines of data suggest that LRRK2 modulation of lysosomal function is involved. It has previously been shown that LRRK2 is recruited to lysosomes upon lysosomal damage leading to increased phosphorylation of its RAB GTPase substrates in macrophage-derived RAW 264.7 cells. Here, we find that LRRK2 kinase inhibition reduces cell death induced by the lysosomotropic compound LLOMe in RAW 264.7 cells showing that lysosomal damage and LRRK2 functionally interacts in both directions: lysosomal damage can lead to activation of LRRK2 signaling and LRRK2 inhibition can attenuate LLOMe-induced cell death. The effect is lysosome specific, as only lysosomal stressors and not a variety of other cell death inducers could be modulated by LRRK2 kinase inhibition. We show with timing and Lysotracker experiments that LRRK2 inhibition does not affect the immediate lysosomal permeabilization induced by LLOMe, but rather modulates the subsequent cellular response to lysosomal damage. siRNA-mediated knockdown of LRRK2 and its main substrates, the RAB GTPases, showed that LRRK2 and RAB8A knockdown could attenuate LLOMe-induced cell death, but not other RAB GTPases tested. An RNA sequencing study was done to identify downstream pathways modulated by LLOMe and LRRK2 inhibition. The most striking finding was that almost all cholesterol biosynthesis genes were strongly downregulated by LLOMe and upregulated with LRRK2 inhibition in combination with LLOMe treatment. To explore the functional relevance of the transcriptional changes, we pretreated cells with the NPC1 inhibitor U18666A that can lead to accumulation of lysosomal cholesterol. U18666A-treated cells were less sensitive to LLOMe-induced cell death, but the attenuation of cell death by LRRK2 inhibition was strongly reduced suggesting that LRRK2 inhibition and lysosomal cholesterol reduces cell death by overlapping mechanisms. Thus, our data demonstrates a LRRK2- and RAB8A-mediated attenuation of RAW 264.7 cell death induced by lysosomal damage that is modulated by lysosomal cholesterol.

Keywords:  Cholesterol; Endolysosomal damage; LRRK2; MLi-2; RNAseq; U18666A; mTOR

DOI:  https://doi.org/10.1016/j.nbd.2024.106728
EMBO J. 2024 Nov 12.

Calcium signaling from damaged lysosomes induces cytoprotective stress granules.

Jacob Duran, Jay E Salinas, Rui Ping Wheaton, Suttinee Poolsup, Lee Allers, Monica Rosas-Lemus, Li Chen, Qiuying Cheng, Jing Pu, Michelle Salemi, Brett Phinney, Pavel Ivanov, Alf Håkon Lystad, Kiran Bhaskar, Jaya Rajaiya, Douglas J Perkins, Jingyue Jia.

  Lysosomal damage induces stress granule (SG) formation. However, the importance of SGs in determining cell fate and the precise mechanisms that mediate SG formation in response to lysosomal damage remain unclear. Here, we describe a novel calcium-dependent pathway controlling SG formation, which promotes cell survival during lysosomal damage. Mechanistically, the calcium-activated protein ALIX transduces lysosomal damage signals to SG formation by controlling eIF2α phosphorylation after sensing calcium leakage. ALIX enhances eIF2α phosphorylation by promoting the association between PKR and its activator PACT, with galectin-3 inhibiting this interaction; these regulatory events occur on damaged lysosomes. We further find that SG formation plays a crucial role in promoting cell survival upon lysosomal damage caused by factors such as SARS-CoV-2ORF3a, adenovirus, malarial pigment, proteopathic tau, or environmental hazards. Collectively, these data provide insights into the mechanism of SG formation upon lysosomal damage and implicate it in diseases associated with damaged lysosomes and SGs.

Keywords:  ALG2-ALIX; Calcium-dependent Pathway; Lysosomal Damage; PACT-PKR-eIF2α; Stress Granules

DOI:  https://doi.org/10.1038/s44318-024-00292-1
Muscle Nerve. 2024 Nov 08.

Gastrostomy in Amyotrophic Lateral Sclerosis: Timing Enhances Survival.

Gary L Pattee.

DOI: https://doi.org/10.1002/mus.28294
Methods Mol Biol. 2025 ;2875 1-7

Live-Cell Imaging of mRNA Using a Pepper RNA Tag.

Jiahui Wu, Samie R Jaffrey.

  Live-cell imaging of mRNA enables tracking of mRNA localization and its dynamics in real time. This is fundamentally important in understanding how cells use RNA to regulate gene expression and orchestrate biological processes. Here, we describe a method of using an engineered RNA tag, called Pepper RNA tag, to visualizing mRNA in living cells. In this method, an mRNA of interest engineered to contain the Pepper RNA tag turns on the fluorescence signals of fluorogenic proteins, which enables tracking of mRNA in living cells.

Keywords:  Fluorogenic proteins; Live-cell RNA imaging; Pepper RNA tag

DOI:  https://doi.org/10.1007/978-1-0716-4248-1_1
Int J Mol Sci. 2024 Oct 22. pii: 11363. [Epub ahead of print]25(21):

Short Peptides Protect Fibroblast-Derived Induced Neurons from Age-Related Changes.

Nina Kraskovskaya, Natalia Linkova, Elena Sakhenberg, Daria Krieger, Victoria Polyakova, Dmitrii Medvedev, Alexander Krasichkov, Mikhail Khotin, Galina Ryzhak.

  Neurons become more vulnerable to stress factors with age, which leads to increased oxidative DNA damage, decreased activity of mitochondria and lysosomes, increased levels of p16, decreased LaminB1 proteins, and the depletion of the dendritic tree. These changes are exacerbated in vulnerable neuronal populations during the development of neurodegenerative diseases. Glu-Asp-Arg (EDR) and Lys-Glu-Asp (KED), and Ala-Glu-Asp-Gly (AEDG) peptides have previously demonstrated neuroprotective effects in various models of Alzheimer's disease. In this study, we investigated the influence of EDR, KED, and AEDG peptides on the aging of fibroblast-derived induced neurons. We used a new in vitro cellular model of human neuronal aging based on the transdifferentiation of aged dermal fibroblasts from elderly donors into induced cortical neurons. All peptides promote the arborization of the dendritic tree, increasing both the number of primary processes and the total length of dendrites. Tripeptides have no effect on the activity of mitochondria and lysosomes and the level of p16 protein in induced neurons. EDR peptide reduces oxidative DNA damage in induced neurons derived from elderly donor fibroblasts. Short peptides partially protect induced neurons from age-related changes and stimulate dendritogenesis in neurons. They can be recommended for use as neuroprotective agents.

Keywords:  aging; dendrites; induced neurons; lysosomes; mitochondria; morphology; oxidative DNA damage; short peptides; tripeptides

DOI:  https://doi.org/10.3390/ijms252111363
Curr Opin Genet Dev. 2024 Nov 12. pii: S0959-437X(24)00124-2. [Epub ahead of print]89 102275

Diversity of human skin three-dimensional organotypic cultures.

Yunlong Y Jia, Scott X Atwood.

Recently, significant strides have been made in the development of high-fidelity skin organoids, encompassing techniques such as 3D bioprinting, skin-on-a-chip systems, and models derived from pluripotent stem cells (PSCs), replicating appendage structures and diverse skin cell types. Despite the emergence of these state-of-the-art skin engineering models, human organotypic cultures (OTCs), initially proposed in the 1970s, continue to reign as the predominant in vitro cultured three-dimensional skin model in the field of tissue engineering. This enduring prevalence is owed to their cost-effectiveness, straight forward setup, time efficiency, and faithful representation of native human skin. In this review, we systematically delineate recent advances in skin OTC models, aiming to inform future efforts to enhance in vitro skin model fidelity and reproducibility.

DOI: https://doi.org/10.1016/j.gde.2024.102275
Life Sci Alliance. 2025 Jan;pii: e202402922. [Epub ahead of print]8(1):

Pathogenic LRRK2 mutations cause loss of primary cilia and Neurturin in striatal parvalbumin interneurons.

Yu-En Lin, Ebsy Jaimon, Francesca Tonelli, Suzanne R Pfeffer.

Parkinson's disease-associated, activating mutations in the LRRK2 kinase block primary cilium formation in cell culture and in specific cell types in the brain. In the striatum that is important for movement control, about half of astrocytes and cholinergic interneurons, but not the predominant medium spiny neurons, lose their primary cilia. Here, we show that mouse and human striatal parvalbumin interneurons that are inhibitory regulators of movement also lose primary cilia. Without cilia, these neurons are not able to respond to Sonic hedgehog signals that normally induce the expression of Patched RNA, and their numbers decrease. In addition, in mouse, glial cell line-derived neurotrophic factor-related Neurturin RNA is significantly decreased. These experiments highlight the importance of parvalbumin neurons in cilium-dependent, neuroprotective signaling pathways and show that LRRK2 activation correlates with decreased Neurturin production, resulting in less neuroprotection for dopamine neurons.

DOI: https://doi.org/10.26508/lsa.202402922
Sci Rep. 2024 11 08. 14(1): 27288

Alternative production of pro-death Bax∆2 protein via ribosomal frameshift in Alzheimer's disease.

Qi Yao, Adriana Mañas, Evan Beatty, Anne Caroline Mascarenhas Dos Santos, Yi Zhou, Oscar Juárez, Hui Chen, Jialing Xiang.

  Pro-death Bax family member, Bax∆2, forms protein aggregates in Alzheimer's disease neurons and causes stress granule-mediated neuronal death. Production of Bax∆2 originated from two events: alternative splicing of Bax exon 2 and a microsatellite mutation (a deletion from poly guanines, G8 to G7). Each event alone leads to a reading frameshift and premature termination. While Bax exon 2 alternative splicing is common in Alzheimer's brains, the G7 mutation is not, which is inconsistent with the high Bax∆2 protein levels detected in clinical samples. Here, we report an alternative mechanism to produce Bax∆2 protein in the absence of the G7 mutation. Using dual-tag systems, we showed that a ribosomal frameshift (RFS) can compensate the lack of G7 mutation in translating Bax∆2 protein. Intriguingly, the microsatellite poly G repeat is neither essential nor the site for the RFS. However, disruption of the poly G sequence impaired the RFS, potentially due to alteration of the local RNA structure. Using immunoprecipitation-mass spectrometry, we pinpointed the RFS site at 15 base pairs upstream of the microsatellite. These results uncover an alternative mechanism for generating functional Bax∆2-subfamily isoforms, highlighting the production plasticity of Bax family isoforms and unveiling potential new therapeutic targets for Alzheimer's disease.

Keywords:  Alzheimer’s disease; Bax; Bax∆2; Cell death; Microsatellite; Ribosomal frameshift

DOI:  https://doi.org/10.1038/s41598-024-76061-1
Nat Commun. 2024 Nov 11. 15(1): 9547

Revealing single-neuron and network-activity interaction by combining high-density microelectrode array and optogenetics.

Toki Kobayashi, Kenta Shimba, Taiyo Narumi, Takahiro Asahina, Kiyoshi Kotani, Yasuhiko Jimbo.

The synchronous activity of neuronal networks is considered crucial for brain function. However, the interaction between single-neuron activity and network-wide activity remains poorly understood. This study explored this interaction within cultured networks of rat cortical neurons. Employing a combination of high-density microelectrode array recording and optogenetic stimulation, we established an experimental setup enabling simultaneous recording and stimulation at a precise single-neuron level that can be scaled to the level of the whole network. Leveraging our system, we identified a network burst-dependent response change in single neurons, providing a possible mechanism for the network-burst-dependent loss of information within the network and consequent cognitive impairment during epileptic seizures. Additionally, we directly recorded a leader neuron initiating a spontaneous network burst and characterized its firing properties, indicating that the bursting activity of hub neurons in the brain can initiate network-wide activity. Our study offers valuable insights into brain networks characterized by a combination of bottom-up self-organization and top-down regulation.

DOI: https://doi.org/10.1038/s41467-024-53505-w
Int J Mol Sci. 2024 Oct 28. pii: 11555. [Epub ahead of print]25(21):

GM1 Oligosaccharide Ameliorates Rett Syndrome Phenotypes In Vitro and In Vivo via Trk Receptor Activation.

Maria Fazzari, Giulia Lunghi, Emma Veronica Carsana, Manuela Valsecchi, Eleonora Spiombi, Martina Breccia, Silvia Rosanna Casati, Silvia Pedretti, Nico Mitro, Laura Mauri, Maria Grazia Ciampa, Sandro Sonnino, Nicoletta Landsberger, Angelisa Frasca, Elena Chiricozzi.

  Rett syndrome (RTT) is a severe neurodevelopmental disorder primarily caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. Despite advancements in research, no cure exists due to an incomplete understanding of the molecular effects of MeCP2 deficiency. Previous studies have identified impaired tropomyosin receptor kinase (Trk) neurotrophin (NTP) signaling and mitochondrial redox imbalances as key drivers of the pathology. Moreover, altered glycosphingolipid metabolism has been reported in RTT. GM1 ganglioside is a known regulator of the nervous system, and growing evidence indicates its importance in maintaining neuronal homeostasis via its oligosaccharide chain, coded as GM1-OS. GM1-OS directly interacts with the Trk receptors on the cell surface, triggering neurotrophic and neuroprotective pathways in neurons. In this study, we demonstrate that GM1-OS ameliorates RTT deficits in the Mecp2-null model. GM1-OS restored synaptogenesis and reduced mitochondrial oxidative stress of Mecp2-knock-out (ko) cortical neurons. When administered in vivo, GM1-OS mitigated RTT-like symptoms. Our findings indicate that GM1-OS effects were mediated by Trk receptor activation on the neuron's plasma membrane. Overall, our results highlight GM1-OS as a promising candidate for RTT treatment.

Keywords:  GM1 ganglioside; GM1 oligosaccharide; Rett syndrome; mitochondrial oxidative stress; neurotrophins’ signaling

DOI:  https://doi.org/10.3390/ijms252111555
Commun Biol. 2024 Nov 12. 7(1): 1495

Single-cell transcriptomics reveals the molecular basis of human iPS cell differentiation into ectodermal ocular lineages.

Laura Howard, Yuki Ishikawa, Tomohiko Katayama, Sung-Joon Park, Matthew J Hill, Derek J Blake, Kohji Nishida, Ryuhei Hayashi, Andrew J Quantock.

The generation of a self-formed, ectodermal, autonomous multi-zone (SEAM) from human induced pluripotent stem cells (hiPSCs) offers a unique perspective to study the dynamics of ocular cell differentiation over time. Here, by utilising single-cell transcriptomics, we have (i) identified, (ii) molecularly characterised and (iii) ascertained the developmental trajectories of ectodermally-derived ocular cell populations which emerge within SEAMs as they form. Our analysis reveals interdependency between tissues of the early eye and delineates the sequential formation and maturation of distinct cell types over a 12-week period. We demonstrate a progression from pluripotency through to tissue specification and differentiation which encompasses both surface ectodermal and neuroectodermal ocular lineages and the generation of iPSC-derived components of the developing cornea, conjunctiva, lens, and retina. Our findings not only advance the understanding of ocular development in a stem cell-based system of human origin, but also establish a robust methodological paradigm for exploring cellular and molecular dynamics during SEAM formation at single-cell resolution and highlight the potential of hiPSC-derived systems as powerful platforms for modelling human eye development and disease.

DOI: https://doi.org/10.1038/s42003-024-07130-4
Heliyon. 2024 Nov 15. 10(21): e39100

Protective effect of zinc against A2E-induced toxicity in ARPE-19 cells: Possible involvement of lysosomal acidification.

Jeong A Choi, Bo-Ra Seo, Jae-Young Koh, Young Hee Yoon.

  A key pathogenic mechanism of dry age-related macular degeneration (AMD) is lysosomal dysfunction in retinal pigment epithelium (RPE) cells, which results in the accumulation of lipofuscins such as A2E (N-retinylidene-N-retinylethanolamine) that further compromises lysosomal function. This vicious cycle leads to cell death and poor visual acuity. Here, we established an in vitro model of AMD by treating a human RPE cell line (ARPE-19) with A2E and examined whether raising zinc levels confers protective effects against lysosomal dysfunction and cytotoxicity. MTT assay showed that A2E induced apoptosis in ARPE-19 cells. pHrodo™ Red fluorescence staining showed that lysosomal pH increased in A2E-treated ARPE-19 cells. Treatment with a zinc ionophore (clioquinol) reduced A2E accumulation, restored lysosomal pH to the acidic range, and reduced A2E-induced cell death, all of which were reversed by the addition of a zinc chelator (TPEN). Consistent with the in vitro results, subretinal injections of A2E in mouse eyes resulted in the death of RPE cells as well as lysosomal dysfunction, all of which were reversed by co-treatment with clioquinol. Our results suggest that restoring the levels of intracellular zinc, especially in lysosomes, would be helpful in mitigating A2E-induced cytotoxic changes including lysosomal dysfunction in RPE cells in the pathogenesis of AMD.

Keywords:  Age-related macular degeneration; Lysosome dysfunction; Retinal pigment epithelium; Zinc

DOI:  https://doi.org/10.1016/j.heliyon.2024.e39100
Neuron. 2024 Nov 06. pii: S0896-6273(24)00732-3. [Epub ahead of print]112(21): 3519-3521

Rev or restrain: Mechanisms of human-specific synaptic neoteny.

Jenelle L Wallace, Alex A Pollen.

In the current issues of Neuron and Cell Reports, Libé-Philippot et al.1 and Assendorp et al.2 identify interactions between human-specific SRGAP2C, synaptic regulator SRGAP2A, and neurodevelopmental disorder-associated proteins SYNGAP1 and CTNND2 that slow synaptic maturation in human neurons.

DOI: https://doi.org/10.1016/j.neuron.2024.10.011
Methods Mol Biol. 2025 ;2863 297-317

Concurrent Profiling of Localized Transcriptome and RNA Dynamics in Neurons by Spatial SLAMseq.

Sayaka Dantsuji, Marina Chekulaeva.

  The asymmetric distribution of RNA within a cell plays a pivotal biological role, ensuring the distinctive shapes and functionality of subcellular compartments. In neurons, these mechanisms are fundamental to cellular growth, synaptic plasticity, and information processing. To understand these mechanisms, diverse methods have been developed to analyze localized transcripts. Here, we outline our optimized method for measurement of mRNA half-lives in subcellular neuronal compartments-neurites, and cytoplasmic and nuclear fractions of cell bodies. We call this method spatial SLAMseq, as it combines SLAMseq with subcellular compartment separation techniques. Spatial SLAMseq facilitates the concurrent measurement of mRNA dynamics and steady-state RNA levels within neuronal subcellular compartments.

Keywords:  High-throughput sequencing; Local translation; Neuron; SLAMseq; mRNA localization; mRNA stability

DOI:  https://doi.org/10.1007/978-1-0716-4176-7_18
Nat Cell Biol. 2024 Nov 15.

FMRP regulates MFF translation to locally direct mitochondrial fission in neurons.

Adam R Fenton, Ruchao Peng, Charles Bond, Siewert Hugelier, Melike Lakadamyali, Yi-Wei Chang, Erika L F Holzbaur, Thomas A Jongens.

Fragile X messenger ribonucleoprotein (FMRP) is a critical regulator of translation, whose dysfunction causes fragile X syndrome. FMRP dysfunction disrupts mitochondrial health in neurons, but it is unclear how FMRP supports mitochondrial homoeostasis. Here we demonstrate that FMRP granules are recruited to the mitochondrial midzone, where they mark mitochondrial fission sites in axons and dendrites. Endolysosomal vesicles contribute to FMRP granule positioning around mitochondria and facilitate FMRP-associated fission via Rab7 GTP hydrolysis. Cryo-electron tomography and real-time translation imaging reveal that mitochondria-associated FMRP granules are ribosome-rich structures that serve as sites of local protein synthesis. Specifically, FMRP promotes local translation of mitochondrial fission factor (MFF), selectively enabling replicative fission at the mitochondrial midzone. Disrupting FMRP function dysregulates mitochondria-associated MFF translation and perturbs fission dynamics, resulting in increased peripheral fission and an irregular distribution of mitochondrial nucleoids. Thus, FMRP regulates local translation of MFF in neurons, enabling precise control of mitochondrial fission.

DOI: https://doi.org/10.1038/s41556-024-01544-2
Dis Model Mech. 2024 Nov 01. pii: dmm052002. [Epub ahead of print]17(11):

Modulation of SNARE-dependent exocytosis in astrocytes improves neuropathology in Huntington's disease.

Annesha C King, Emily Payne, Emily Stephens, Jahmel A Fowler, Tara E Wood, Efrain Rodriguez, Michelle Gray.

  Huntington's disease (HD) is a fatal, progressive neurodegenerative disorder. Prior studies revealed an increase in extracellular glutamate levels after evoking astrocytic SNARE-dependent exocytosis from cultured primary astrocytes from mutant huntingtin (mHTT)-expressing BACHD mice compared to control astrocytes, suggesting alterations in astrocytic SNARE-dependent exocytosis in HD. We used BACHD and dominant-negative (dn)SNARE mice to decrease SNARE-dependent exocytosis from astrocytes to determine whether reducing SNARE-dependent exocytosis from astrocytes could rescue neuropathological changes in vivo. We observed significant protection against striatal atrophy and no significant rescue of cortical atrophy in BACHD/dnSNARE mice compared to BACHD mice. Amino acid transporters are important for modulating the levels of extracellular neurotransmitters. BACHD mice had no change in GLT1 expression, decreased striatal GAT1 expression and increased levels of GAT3. There was no change in GAT1 after reducing astrocytic SNARE-dependent exocytosis, and increased GAT3 expression in BACHD mice was normalized in BACHD/dnSNARE mice. Thus, modulation of astrocytic SNARE-dependent exocytosis in BACHD mice is protective against striatal atrophy and modulates GABA transporter expression.

Keywords:  Astrocytes; BACHD; Huntington's disease; SNARE-dependent exocytosis; dnSNARE

DOI:  https://doi.org/10.1242/dmm.052002