bims-axbals 2024-12-22 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2024–12–22
thirty-two papers selected by
TJ Krzystek, ALS Therapy Development Institute

C21ORF2 mutations point towards primary cilia dysfunction in amyotrophic lateral sclerosis.
Plasma extracellular vesicle: a novel biomarker for neurodegenerative disease diagnosis.
Autophagy induction by piplartine ameliorates axonal degeneration caused by mutant HSPB1 and HSPB8 in charcot-marie-tooth type 2 neuropathies.
A model of inborn metabolism errors associated with adenine amyloid-like fiber formation reduces TDP-43 aggregation and toxicity in yeast.
Structural and functional alterations of neurons derived from sporadic Alzheimer's disease hiPSCs are associated with downregulation of the LIMK1-cofilin axis.
CoCrMo nanoparticle induces neurotoxicity mediated via mitochondrial dysfunction: a study model for implant derived nanoparticle effects.
Ascorbic Acid Ameliorates Molecular and Developmental Defects in Human-Induced Pluripotent Stem Cell and Cerebral Organoid Models of Fragile X Syndrome.
Astrocytes contribute to toll-like receptor 2-mediated neurodegeneration and alpha-synuclein pathology in a human midbrain Parkinson's model.
Neuronal activity inhibits mitochondrial transport only in synaptically connected segments of the axon.
Endocytosis in the axon initial segment: Roles in neuronal polarity and plasticity.
Examining the potential involvement of NONO in TDP-43 proteinopathy in Drosophila.
A Commentary on Mitochondrial Dysfunction and Compromised DNA Repair in Neurodegeneration: The Emerging Role of FUS in ALS.
Human-Induced Pluripotent Stem Cell-Derived Neural Organoids as a Novel In Vitro Platform for Developmental Neurotoxicity Assessment.
A molecular glue for Prkn/parkin.
Metaxin-2 tunes mitochondrial transportation and neuronal function in Drosophila.
Editorial: Mechanisms of neurodegeneration in amyotrophic lateral sclerosis and related disorders.
Determining ATG2 Localization During Autophagosome Formation in Mammalian Cells.
A consensus platform for antibody characterization.
Matrix-free human lung organoids derived from induced pluripotent stem cells to model lung injury.
The Neuroprotective Effect of the X Protein of Orthobornavirus Bornaense Type 1 in Amyotrophic Lateral Sclerosis.
A dataset profiling the multiomic landscape of the prefrontal cortex in amyotrophic lateral sclerosis.
Mitochondrial Dynamics in Brain Cells During Normal and Pathological Aging.
Intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism.
The UFMylation pathway is impaired in Alzheimer's disease.
IL-1ra and CCL5, but not IL-10, are promising targets for treating SMA astrocyte-driven pathology.
Consciousness and the Axon Initial Segment.
Amyotrophic lateral sclerosis in a tricenarian female.
Phase separation of microtubule-binding proteins - implications for neuronal function and disease.
Discovery of a Small Molecule with an Inhibitory Role for RAB11.
Neuronal Cell Rearrangement During Aging: Antioxidant Compounds as a Potential Therapeutic Approach.
Aged neurons don't register energy need.
Neurochemical and Morphological Comparisons of Motor Nerve Organoids and Spinal-Cord Explants.

Brain. 2024 Dec 20. pii: awae331. [Epub ahead of print]

C21ORF2 mutations point towards primary cilia dysfunction in amyotrophic lateral sclerosis.

Mathias De Decker, Pavol Zelina, Thomas G Moens, Jimmy Beckers, Matilde Contardo, Katarina Stoklund Dittlau, Evelien Van Schoor, Alicja Ronisz, Kristel Eggermont, Matthieu Moisse, Siddharthan Chandran, Jan H Veldink, Dietmar Rudolf Thal, Ludo Van Den Bosch, R Jeroen Pasterkamp, Philip Van Damme.

  Progressive loss of motor neurons is the hallmark of the neurodegenerative disease amyotrophic lateral sclerosis (ALS), but the underlying disease mechanisms remain incompletely understood. In this study, we investigate the effects of C21ORF2 mutations, a gene recently linked to ALS, and find that primary cilia are dysfunctional. Human patient-derived mutant C21ORF2 motor neurons have a reduced ciliary frequency and length. We report that C21ORF2 is located at the basal body of the primary cilium, and mutations associated with ALS alter this localization. Furthermore, we show that a reduction of C21ORF2 levels in cell lines and motor neurons is sufficient to cause fewer primary cilia and reduced cilial length. This ciliary dysfunction leads to defective downstream sonic hedgehog signalling and reduces the expression of cellular retinoic acid binding protein 1 (CRABP1), a protein involved in motor neuron maintenance and survival. In a compartmentalized co-culture system of motor neurons and muscle cells, these ciliary defects were associated with a reduced ability of neuromuscular junction formation. Interestingly, these cilia defects are seemingly not restricted to C21ORF2 ALS, as we also observed perturbed primary cilia in cultured motor neurons and post-mortem motor cortex from patients with the most common genetic subtype of ALS caused by repeat expansions in the C9ORF72 gene. Finally, overexpression of C21ORF2 in mutant C21ORF2 motor neurons rescued the ciliary frequency and length, CRAPBP1 expression and neuromuscular junction formation, confirming the importance of primary cilia for motor neuron function. These results point towards primary cilia dysfunction contributing to motor neuron degeneration in ALS and open new avenues for further research and interventions for this as yet untreatable disease.

Keywords:  ALS; C21ORF2; CFAP410; amyotrophic lateral sclerosis; motor neuron disease; primary cilia

DOI:  https://doi.org/10.1093/brain/awae331
Extracell Vesicles Circ Nucl Acids. 2024 ;5(3): 569-573

Plasma extracellular vesicle: a novel biomarker for neurodegenerative disease diagnosis.

Xinrui Zhao, Shenglin Huang.

  Extracellular vesicles (EVs) are membrane-bound structures that carry proteins, lipids, RNA, and DNA, playing key roles in cell communication and material transport. Recent research highlights their potential as disease biomarkers due to their stability in bodily fluids. This study explores using tau and TDP-43 proteins in plasma EVs as diagnostic biomarkers for frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Analyzing plasma EVs from clinical cohorts, the study found that the 3R/4R tau ratio and TDP-43 levels effectively differentiate between diagnostic groups with high accuracy. Notably, plasma EV biomarkers demonstrate higher diagnostic accuracy and stability compared to direct plasma testing, providing new insights and approaches for future research and clinical practice. Further research is needed to validate these biomarkers in diverse populations and to establish standardized protocols. Future studies should continue to explore the potential of EV biomarkers in a broader range of neurodegenerative diseases and delve deeper into the mechanisms of EV secretion and sorting to enhance their diagnostic utility.

Keywords:  Neurodegenerative diseases; TDP-43; Tau; diagnostic marker; plasma extracellular vesicle

DOI:  https://doi.org/10.20517/evcna.2024.56
Autophagy. 2024 Dec 19.

Autophagy induction by piplartine ameliorates axonal degeneration caused by mutant HSPB1 and HSPB8 in charcot-marie-tooth type 2 neuropathies.

Angela Sisto, Tamira van Wermeskerken, Michael Pancher, Pamela Gatto, Bob Asselbergh, Ágata Sofia Assunção Carreira, Vicky De Winter, Valentina Adami, Alessandro Provenzani, Vincent Timmerman.

  HSPB1 [heat shock protein family B (small) member 1] and HSPB8 are essential molecular chaperones for neuronal proteostasis, as they prevent protein aggregation. Mutant HSPB1 and HSPB8 primarily harm peripheral neurons, resulting in axonal Charcot-Marie-Tooth neuropathies (CMT2). Macroautophagy/autophagy is a shared mechanism by which HSPB1 and HSPB8 mutations cause neuronal dysfunction. Autophagosome formation is reduced in mutant HSPB1-induced pluripotent stem-cell-derived motor neurons from CMT type 2F patients. Likewise, the HSPB8K141N knockin mouse model, mimicking CMT type 2 L, exhibits axonal degeneration and muscle atrophy, with SQSTM1/p62-positive deposits. We show here that mouse embryonic fibroblasts isolated from a HSPB8K141N/green fluorescent protein (GFP)-LC3 model have diminished autophagosome production under conditions of MTOR inhibition. To correct the autophagic deficits in the HSPB1 and HSPB8 models, we screened by high-throughput autophagosome quantification the repurposing Spectrum Collection library for molecules that could boost the autophagic activity above the canonical MTOR inhibition. Hit compounds were validated on motor neurons obtained by differentiation of HSPB1P182L and HSPB8K141N patient-derived induced pluripotent stem cells, focusing on autophagy induction as well as neurite network density, axonal degeneration, and mitochondrial morphology. We identified molecules that specifically stimulate autophagosome formation in the HSPB8K141N cells, without affecting autophagy flux. Two top lead compounds induced autophagy and reduced axonal degeneration, thus promoting neuronal network maturation in the CMT2 patient-derived motor neurons. Based on these findings, the phenotypical screen revealed that piplartine rescued autophagy deficiencies in both the HSPB1 and HSPB8 models, demonstrating autophagy induction as an effective therapeutic strategy for CMT neuropathies and other chaperonopathies.

Keywords:  Autophagy inducer; drug repurposing; inherited peripheral neuropathy; motor neurons; phenotypical screening; small heat shock proteins

DOI:  https://doi.org/10.1080/15548627.2024.2439649
bioRxiv. 2024 Dec 07. pii: 2024.12.03.626668. [Epub ahead of print]

A model of inborn metabolism errors associated with adenine amyloid-like fiber formation reduces TDP-43 aggregation and toxicity in yeast.

Sangeun Park, Sei-Kyoung Park, Susan W Liebman.

TDP-43 is linked to human diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). Expression of TDP-43 in yeast is known to be toxic, cause cells to elongate, form liquid-like aggregates, and inhibit autophagy and TOROID formation. Here, we used the apt1Δ aah1Δ yeast model of disorders of inborn errors of metabolism, previously shown to lead to intracellular adenine accumulation and adenine amyloid-like fiber formation, to explore interactions with TDP-43. Results show that the double deletion shifts the TDP-43 aggregates from a liquid-like, toward a more amyloid-like, state. At the same time the deletions reduce TDP-43's effects on toxicity, cell morphology, autophagy, and TOROID formation without affecting the level of TDP-43. This suggests that the liquid-like and not amyloid-like TDP-43 aggregates are responsible for the deleterious effects in yeast. How the apt1Δ aah1Δ deletions alter TDP-43 aggregate formation is not clear. Possibly, it results from adenine/TDP-43 fiber interactions as seen for other heterologous fibers. The work offers new insights into the potential interactions between metabolite-based amyloids and pathological protein aggregates, with broad implications for understanding protein misfolding diseases.

DOI: https://doi.org/10.1101/2024.12.03.626668
Alzheimers Res Ther. 2024 Dec 19. 16(1): 267

Structural and functional alterations of neurons derived from sporadic Alzheimer's disease hiPSCs are associated with downregulation of the LIMK1-cofilin axis.

Raimondo Sollazzo, Domenica Donatella Li Puma, Giuseppe Aceto, Fabiola Paciello, Claudia Colussi, Maria Gabriella Vita, Guido Maria Giuffrè, Francesco Pastore, Alessia Casamassa, Jessica Rosati, Agnese Novelli, Sabrina Maietta, Francesco Danilo Tiziano, Camillo Marra, Cristian Ripoli, Claudio Grassi.

   BACKGROUND: Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by the accumulation of pathological proteins and synaptic dysfunction. This study aims to investigate the molecular and functional differences between human induced pluripotent stem cells (hiPSCs) derived from patients with sporadic AD (sAD) and age-matched controls (healthy subjects, HS), focusing on their neuronal differentiation and synaptic properties in order to better understand the cellular and molecular mechanisms underlying AD pathology.
METHODS: Skin fibroblasts from sAD patients (n = 5) and HS subjects (n = 5) were reprogrammed into hiPSCs using non-integrating Sendai virus vectors. Through karyotyping, we assessed pluripotency markers (OCT4, SOX2, TRA-1-60) and genomic integrity. Neuronal differentiation was evaluated by immunostaining for MAP2 and NEUN. Electrophysiological properties were measured using whole-cell patch-clamp, while protein expression of Aβ, phosphorylated tau, Synapsin-1, Synaptophysin, PSD95, and GluA1 was quantified by western blot. We then focused on PAK1-LIMK1-Cofilin signaling, which plays a key role in regulating synaptic structure and function, both of which are disrupted in neurodegenerative diseases such as AD.
RESULTS: sAD and HS hiPSCs displayed similar stemness features and genomic stability. However, they differed in neuronal differentiation and function. sAD-derived neurons (sAD-hNs) displayed increased levels of AD-related proteins, including Aβ and phosphorylated tau. Electrophysiological analyses revealed that while both sAD- and HS-hNs generated action potentials, sAD-hNs exhibited decreased spontaneous synaptic activity. Significant reductions in the expression of synaptic proteins such as Synapsin-1, Synaptophysin, PSD95, and GluA1 were found in sAD-hNs, which are also characterized by reduced neurite length, indicating impaired differentiation. Notably, sAD-hNs demonstrated a marked reduction in LIMK1 phosphorylation, which could be the underlying cause for the changes in cytoskeletal dynamics that we found, leading to the morphological and functional modifications observed in sAD-hNs. To further investigate the involvement of the LIMK1 pathway in the morphological and functional changes observed in sAD neurons, we conducted perturbation experiments using the specific LIMK1 inhibitor, BMS-5. Neurons obtained from healthy subjects treated with the inhibitor showed similar morphological changes to those observed in sAD neurons, confirming that LIMK1 activity is crucial for maintaining normal neuronal structure. Furthermore, administration of the inhibitor to sAD neurons did not exacerbate the morphological alterations, suggesting that LIMK1 activity is already compromised in these cells.
CONCLUSION: Our findings demonstrate that although sAD- and HS-hiPSCs are similar in their stemness and genomic stability, sAD-hNs exhibit distinct functional and structural anomalies mirroring AD pathology. These anomalies include synaptic dysfunction, altered cytoskeletal organization, and accumulation of AD-related proteins. Our study underscores the usefulness of hiPSCs in modeling AD and provides insights into the disease's molecular underpinnings, thus highlighting potential therapeutic targets.

Keywords:  Alzheimer’s disease; Human neurons; LIMK1; Neurites; Synaptic function; hiPSCs

DOI:  https://doi.org/10.1186/s13195-024-01632-3
Nanotoxicology. 2024 Dec;18(8): 707-723

CoCrMo nanoparticle induces neurotoxicity mediated via mitochondrial dysfunction: a study model for implant derived nanoparticle effects.

Priyadarshini Vijayakumar, Yongchao Mou, Xuejun Li, Jahnavi Anil, Neeraja Revi, Kai-Yuan Cheng, Mathew T Mathew, Divya Bijukumar.

  Toxicity associated with elevated levels of cobalt-chromium-molybdenum (CoCrMo) nanoparticles in total hip replacement (THR) patients has been a rising concern. Recent investigations demonstrated that these particles can induce polyneuropathy in THR patients. The current study aims to address a detailed molecular investigation of CoCrMo nanoparticle-mediated mitochondrial dynamics using induced pluripotent stem cell-derived neurons (iPSC neurons). Telencephalic neurons from iPSCs were used in this study. A statistically significant dose-dependent reduction in membrane potential and mitochondrial superoxide generation was observed after CoCrMo nanoparticle treatment. The gene expression analysis confirmed that the oxidative-specific genes were significantly upregulated in particle-treated cells compared to untreated cells. When iPSCs were exposed to CoCrMo nanoparticles, there was a significant reduction in the area, perimeter, and length of mitochondria. Live cell imaging (mitochondrial tracking) revealed a significant reduction in mitochondrial movements in the presence of CoCrMo nanoparticles. Further protein expression confirmed increased mitochondrial fission in CoCrMo particle-treated cells by significantly upregulating Drp-1 protein and downregulating Mfn-2. In conclusion, the results show that CoCrMo nanoparticles can significantly alter neuronal mitochondrial dynamics. The disturbance in balance restricts mitochondrial movement, reduces energy production, increases oxidative stress, and can cause subsequent neurodegeneration.

Keywords:  CoCrMo; THR; iPSC neurons; mitochondrial dynamics; nanoparticles

DOI:  https://doi.org/10.1080/17435390.2024.2438118
Int J Mol Sci. 2024 Nov 26. pii: 12718. [Epub ahead of print]25(23):

Ascorbic Acid Ameliorates Molecular and Developmental Defects in Human-Induced Pluripotent Stem Cell and Cerebral Organoid Models of Fragile X Syndrome.

Keith M Gunapala, Aseel Gadban, Faiza Noreen, Primo Schär, Nissim Benvenisty, Verdon Taylor.

  Fragile X Syndrome (FX) is the most common form of inherited cognitive impairment and falls under the broader category of Autism Spectrum Disorders (ASD). FX is caused by a CGG trinucleotide repeat expansion in the non-coding region of the X-linked Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene, leading to its hypermethylation and epigenetic silencing. Animal models of FX rely on the deletion of the Fmr1 gene, which fails to replicate the epigenetic silencing mechanism of the FMR1 gene observed in human patients. Human stem cells carrying FX repeat expansions have provided a better understanding of the basis of epigenetic silencing of FMR1. Previous studies have found that 5-Azacytidine (5Azac) can reverse this methylation; however, 5Azac can be toxic, which may limit its therapeutic potential. Here, we show that the dietary factor Ascorbic Acid (AsA) can reduce DNA methylation in the FMR1 locus and lead to an increase in FMR1 gene expression in FX iPSCs and cerebral organoids. In addition, AsA treatment rescued neuronal gene expression and morphological defects observed in FX iPSC-derived cerebral organoids. Hence, we demonstrate that the dietary co-factor AsA can partially revert the molecular and morphological defects seen in human FX models in vitro. Our findings have implications for the development of novel therapies for FX in the future.

Keywords:  Ascorbic Acid; Autism Spectrum Disorders (ASD); FMR1; Fragile X Syndrome; cerebral organoids; gene silencing; induced pluripotent stem cells; methylation; neurodevelopmental disorders

DOI:  https://doi.org/10.3390/ijms252312718
Transl Neurodegener. 2024 Dec 16. 13(1): 62

Astrocytes contribute to toll-like receptor 2-mediated neurodegeneration and alpha-synuclein pathology in a human midbrain Parkinson's model.

Fiona Weiss, Laura Hughes, Yuhong Fu, Cedric Bardy, Glenda M Halliday, Nicolas Dzamko.

   BACKGROUND: Parkinson's disease (PD) is characterised by degeneration of ventral midbrain dopaminergic (DA) neurons and abnormal deposition of α-synuclein (α-syn) in neurons. Activation of the innate immune pathogen recognition receptor toll-like receptor 2 (TLR2) is associated with exacerbation of α-syn pathology. TLR2 is increased on neurons in the PD brain, and its activation results in the accumulation and propagation of α-syn through autophagy inhibition in neurons. In addition to the aggregation and propagation of pathological α-syn, dysfunction of astrocytes may contribute to DA neuronal death and subsequent clinical progression of PD. However, the role of astrocytes in TLR2-mediated PD pathology is less explored but important to address, given that TLR2 is a potential therapeutic target for PD.
METHODS: Induced pluripotent stem cells from three controls and three PD patients were differentiated into a midbrain model comprised of neurons (including DA neurons) and astrocytes. Cells were treated with or without the TLR2 agonist Pam3CSK4, and α-syn pathology was seeded using pre-formed fibrils. Confocal imaging was used to assess lysosomal function and α-syn pathology in the different cell types, as well as DA neuron health and astrocyte activation.
RESULTS: TLR2 activation acutely impaired the autophagy lysosomal pathway, and potentiated α-syn pathology seeded by pre-formed fibrils in PD neurons and astrocytes, leading to degeneration and loss of DA neurons. The astrocytes displayed impaired chaperone-mediated autophagy reducing their ability to clear accumulated α-syn, and increases of A1 neurotoxic phenotypic proteins SerpinG1, complement C3, PSMB8 and GBP2. Moreover, the phenotypic changes in astrocytes correlated with a specific loss of DA neurons.
CONCLUSIONS: Taken together, these results support a role for astrocyte dysfunction in α-syn accumulation and DA neuronal loss following TLR2 activation in PD.

Keywords:  Alpha-synuclein; Astrocyte; Lysosome; Parkinson’s disease; Toll-like receptor 2

DOI:  https://doi.org/10.1186/s40035-024-00448-3
Front Cell Neurosci. 2024 ;18 1509283

Neuronal activity inhibits mitochondrial transport only in synaptically connected segments of the axon.

Tom Venneman, Pieter Vanden Berghe.

  Due to their large scale and uniquely branched architecture, neurons critically rely on active transport of mitochondria in order to match energy production and calcium buffering to local demand. Consequently, defective mitochondrial trafficking is implicated in various neurological and neurodegenerative diseases. A key signal regulating mitochondrial transport is intracellular calcium. Elevated Ca2+ levels have been demonstrated to inhibit mitochondrial transport in many cell types, including neurons. However, it is currently unclear to what extent calcium-signaling regulates axonal mitochondrial transport during realistic neuronal activity patterns. We created a robust pipeline to quantify with high spatial resolution, absolute Ca2+ concentrations. This allows us to monitor Ca2+ dynamics with pixel precision in the axon and other neuronal compartments. We found that axonal calcium levels scale with firing frequency in the range of 0.1-1 μM, whereas KCl-induced depolarization generated levels almost a magnitude higher. As expected, prolonged KCl-induced depolarization did inhibit axonal mitochondrial transport in primary hippocampal neurons. However, physiologically relevant neuronal activity patterns only inhibited mitochondrial transport in axonal segments which made connections to a target neuron. In "non-connecting" axonal segments, we were unable to trigger this inhibitory mechanism using realistic firing patterns. Thus, we confirm that neuronal activity can indeed regulate axonal mitochondrial transport, and reveal a spatial pattern to this regulation which went previously undetected. Together, these findings indicate a potent, but localized role for activity-related calcium fluctuations in the regulation of axonal mitochondrial transport.

Keywords:  axonal mitochondrial transport; neuronal activity; ratiometric calcium imaging; synaptic connections; transport regulation

DOI:  https://doi.org/10.3389/fncel.2024.1509283
Curr Opin Neurobiol. 2024 Dec 16. pii: S0959-4388(24)00111-9. [Epub ahead of print]90 102949

Endocytosis in the axon initial segment: Roles in neuronal polarity and plasticity.

Kelsie Eichel.

The axon initial segment (AIS) is a specialized domain that maintains neuronal polarity and is the site of action potential generation, both of which underlie the neuron's ability to send and receive signals. Disruption of the AIS leads to a loss of neuronal polarity, altered neuronal signaling, and an array of neurological disorders. Therefore, understanding how the AIS forms and functions is a central question in cellular neuroscience that is essential to understanding neuronal physiology. Decades of study have identified many molecular components and mechanisms at the AIS. Recently, endocytosis at the AIS has been identified to function in both maintaining neuronal polarity and in mediating AIS plasticity through its ability to dynamically remodel the plasma membrane composition. This review discusses the emerging evidence for the roles of endocytosis in regulating AIS function and structural insights into how endocytosis can occur at the AIS.

DOI: https://doi.org/10.1016/j.conb.2024.102949
Eur J Neurosci. 2024 Dec 17.

Examining the potential involvement of NONO in TDP-43 proteinopathy in Drosophila.

Rafael Koch, Emi Nagoshi.

  The misfolding and aggregation of TAR DNA binding protein-43 (TDP-43), leading to the formation of cytoplasmic inclusions, emerge as a key pathological feature in a spectrum of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD). TDP-43 shuttles between the nucleus and cytoplasm but forms nuclear bodies (NBs) in response to stress. These NBs partially colocalise with nuclear speckles and paraspeckles that sequester RNAs and proteins, thereby regulating many cellular functions. The laboratory of Steven Brown has recently found that the non-POU domain-containing octamer-binding protein (NONO), a component of paraspeckles, forms novel nuclear speckle-like structures in mouse cortical neurons in response to stress and sleep deprivation. These findings suggest the possibility of a functional link between NONO and TDP-43, potentially contributing to TDP-43 proteinopathy. Here, we demonstrate that pathological phenotypes caused by TDP-43 gain of function-locomotor defects and life span shortening-are exacerbated by silencing the Drosophila homolog of NONO, no on or off transient A (NonA). Additionally, NonA silencing results in an increase in nuclear TDP-43 NBs. These results provide supporting evidence for the functional link between NONO and TDP-43 and lay the foundation for dissecting underlying mechanisms.

Keywords:  lifespan; locomotor deficits; neurodegenerative disorders; nuclear bodies

DOI:  https://doi.org/10.1111/ejn.16632
Neurosci Insights. 2024 ;19 26331055241305151

A Commentary on Mitochondrial Dysfunction and Compromised DNA Repair in Neurodegeneration: The Emerging Role of FUS in ALS.

Manohar Kodavati, Muralidhar L Hegde.

  Mitochondrial dysfunction plays a pivotal role in the progression of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's, and Parkinson's disease. Recent discoveries have highlighted the involvement of DNA damage and repair processes, particularly mitochondrial DNA (mtDNA) damage, in these conditions. This commentary reflects on our recent findings, demonstrating the RNA/DNA binding protein fused in sarcoma (FUS)'s crucial role in maintaining mtDNA integrity through interactions with mitochondrial DNA ligase IIIα (mtLig3). Our studies provide direct evidence of increased mtDNA damage in ALS-linked FUS mutant cells, emphasizing the potential of targeting DNA repair pathways to mitigate neurodegeneration. Furthermore, the restoration of mitochondrial function through targeted expression of human DNA ligase 1 (Lig1) in FUS mutant models showcases the therapeutic promise of DNA repair mechanisms in neurodegenerative diseases. These insights offer new molecular understanding and open up future avenues for therapeutic interventions, particularly in FUS-associated ALS and related disorders.

Keywords:  ALS; DNA damage; DNA ligase; mitochondria; neurodegeneration

DOI:  https://doi.org/10.1177/26331055241305151
Int J Mol Sci. 2024 Nov 21. pii: 12523. [Epub ahead of print]25(23):

Human-Induced Pluripotent Stem Cell-Derived Neural Organoids as a Novel In Vitro Platform for Developmental Neurotoxicity Assessment.

Tsunehiko Hongen, Kenta Sakai, Tomohiro Ito, Xian-Yang Qin, Hideko Sone.

  There has been a recent drive to replace in vivo studies with in vitro studies in the field of toxicity testing. Therefore, instead of conventional animal or planar cell culture models, there is an urgent need for in vitro systems whose conditions can be strictly controlled, including cell-cell interactions and sensitivity to low doses of chemicals. Neural organoids generated from human-induced pluripotent stem cells (iPSCs) are a promising in vitro platform for modeling human brain development. In this study, we developed a new tool based on various iPSCs to study and predict chemical-induced toxicity in humans. The model displayed several neurodevelopmental features and showed good reproducibility, comparable to that of previously published models. The results revealed that basic fibroblast growth factor plays a key role in the formation of the embryoid body, as well as complex neural networks and higher-order structures such as layered stacking. Using organoid models, pesticide toxicities were assessed. Cells treated with low concentrations of rotenone underwent apoptosis to a greater extent than those treated with high concentrations of rotenone. Morphological changes associated with the development of neural progenitor cells were observed after exposure to low doses of chlorpyrifos. These findings suggest that the neuronal organoids developed in this study mimic the developmental processes occurring in the brain and nerves and are a useful tool for evaluating drug efficacy, safety, and toxicity.

Keywords:  developmental neurotoxicity; human induced pluripotent stem cells; in vitro; neural organoid

DOI:  https://doi.org/10.3390/ijms252312523
Autophagy. 2024 Dec 19.

A molecular glue for Prkn/parkin.

Véronique Sauvé, Kalle Gehring.

  Parkinson disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra, primarily due to mitochondria dysfunction. PRKN (parkin RBR E3 ubiquitin protein ligase) and PINK1 (PTEN induced kinase 1) are linked to early-onset cases of PD and essential for the clearance of damaged mitochondria via selective mitochondrial autophagy (mitophagy). In a recent publication, we detail how a small molecule can activate PRKN mutants that are unable to be phosphorylated, restoring mitophagy in cellular assays. These findings offer hope for the design of therapeutic drugs for some forms of PD.

Keywords:  Activator; PARK2; mitochondria; neurodegeneration; parkinson disease; ubiquitin

DOI:  https://doi.org/10.1080/15548627.2024.2443232
Genetics. 2024 Dec 05. pii: iyae204. [Epub ahead of print]

Metaxin-2 tunes mitochondrial transportation and neuronal function in Drosophila.

Ting Zhang, Ling Li, Xiaoyu Fan, Xinyi Shou, Yina Ruan, Xiaojun Xie.

  Metaxins are a family of evolutionarily conserved proteins that reside on the mitochondria outer membrane (MOM) and participate in the protein import into the mitochondria. Metaxin-2 (Mtx2), a member of this family, has been identified as a key component in the machinery for mitochondrial transport in both C. elegans and human neurons. To deepen our understanding of Mtx2's role in neurons, we examined the homologous genes CG5662 and CG8004 in Drosophila. The CG5662 is a non-essential gene while CG8004 null mutants die at late pupal stages. The CG8004 protein is widely expressed throughout the Drosophila nervous system and is targeted to mitochondria. However, neuronal CG8004 is dispensable for animal survival and is partially required for mitochondrial distribution in certain neuropil regions. Conditional knockout of CG8004 in adult gustatory receptor neurons (GRNs) impairs mitochondrial trafficking along GRN axons and diminishes the mitochondrial quantities in axon terminals. The absence of CG8004 also leads to mitochondrial fragmentation within GRN axons, a phenomenon that may be linked to mitochondrial transport through its genetic interaction with the fusion proteins Marf and Opa1. While the removal of neuronal CG8004 is not lethal during the developmental stage, it does have consequences for the lifespan and healthspan of adult Drosophila. At last, double knockout (KO) of CG5662 and CG8004 shows similar phenotypes as the CG8004 single KO, suggesting that CG5662 does not compensate for the loss of CG8004. In summary, our findings suggest that CG8004 plays a conserved and context-dependent role in axonal mitochondrial transport, as well it is important for sustaining neuronal function. Therefore, we refer to CG8004 as the Drosophila Metaxin-2 (dMtx2).

Keywords:   Drosophila ; Mandibuloacral dysplasia; Metaxin; Mitochondria dynamics; Mitochondria transport

DOI:  https://doi.org/10.1093/genetics/iyae204
Front Cell Neurosci. 2024 ;18 1531449

Editorial: Mechanisms of neurodegeneration in amyotrophic lateral sclerosis and related disorders.

Danyllo Oliveira, Agnes Lumi Nishimura.



Keywords:  Mendelian randomization; amyotrophic lateral sclerosis; disease mechanisms; genetic risk factor; myopathy; neurodegeneration; spinal muscular atrophy

DOI:  https://doi.org/10.3389/fncel.2024.1531449
Methods Mol Biol. 2025 ;2888 193-200

Determining ATG2 Localization During Autophagosome Formation in Mammalian Cells.

Shenliang Yu.

  This chapter describes two imaging-based approaches for examining the localization of bridge-like lipid transfer proteins at membrane contact sites during native biological processes. These approaches use multi-color fluorescence imaging, enabling high spatial and temporal resolution and overcoming the limitations of biochemical methods. The first approach involves immunofluorescence in fixed cells, while the second utilizes time-lapse imaging in live cells. These methods are showcased through the example of ATG2, an essential autophagy-related protein, and demonstrate the ability to overcome technical difficulties such as large protein size, lack of high-quality antibodies, and imaging highly dynamic subcellular structures. These described methods provide a powerful tool for understanding protein function and biological processes and can be widely applied to various research questions in cell biology.

Keywords:  ATG2; Autophagy; Fluorescence microscopy; Lipid transport; Membrane contact site

DOI:  https://doi.org/10.1007/978-1-0716-4318-1_13
Nat Protoc. 2024 Dec 17.

A consensus platform for antibody characterization.

Riham Ayoubi, Joel Ryan, Sara Gonzalez Bolivar, Charles Alende, Vera Ruiz Moleon, Maryam Fotouhi, Mona Alqazzaz, Kathleen Southern, Walaa Alshafie, Matt R Baker, Alexander R Ball, Danielle Callahan, Jeffery A Cooper, Katherine Crosby, Kevin J Harvey, Douglas W Houston, Ravindran Kumaran, Meghan Rego, Christine Schofield, Hai Wu, Michael S Biddle, Claire M Brown, Richard A Kahn, Anita Bandrowski, Harvinder S Virk, Aled M Edwards, Peter S McPherson, Carl Laflamme.

Antibody-based research applications are critical for biological discovery. Yet there are no industry standards for comparing the performance of antibodies in various applications. We describe a knockout cell line-based antibody characterization platform, developed and approved jointly by industry and academic researchers, that enables the systematic comparison of antibody performance in western blot, immunoprecipitation and immunofluorescence. The scalable protocols, which require minimal technological resources, consist of (1) the identification of appropriate cell lines for antibody characterization studies, (2) development/contribution of isogenic knockout controls, and (3) a series of antibody characterization procedures focused on the most common applications of antibodies in research. We provide examples of expected outcomes to guide antibody users in evaluating antibody performance. Central to our approach is advocating for transparent and open data sharing, enabling a community effort to identify specific antibodies for all human proteins. Mid-level graduate students with training in biochemistry and prior experience in cell culture and microscopy can complete the protocols for a specific protein within 1 month while working part-time on this effort. Antibody characterization is needed to meet standards for resource validation and data reproducibility, which are increasingly required by journals and funding agencies.

DOI: https://doi.org/10.1038/s41596-024-01095-8
Stem Cell Res Ther. 2024 Dec 18. 15(1): 468

Matrix-free human lung organoids derived from induced pluripotent stem cells to model lung injury.

Bettina Budeus, Chiara Kroepel, Lisa Marie Stasch, Diana Klein.

   BACKGROUND: Organoids, as near-physiological 3D culture systems, offer new opportunities to study the pathogenesis of various organs in mimicking the cellular complexity and functionality of human organs.
METHOD: Here we used a quite simple and very practicable method to successfully generate induced pluripotent stem cell (iPSC)-derived human lung organoids (LuOrg) in a matrix-free manner as an alternative to the widely used preclinical mouse models in order to investigate normal lung damage in detail and as close as possible to the patient. We performed detailed morphological and molecular analyses, including bulk and single cell RNA sequencing, of generated lung organoids and evaluated the quality and robustness of our model as a potential in vitro platform for lung diseases, namely radiation-induced lung injury.
RESULTS: A matrix-free method for differentiation of iPSCs can be used to obtain lung organoids that morphologically reflect the target tissue of the human lung very well, especially with regard to the cellular composition. The different cellular fates were investigated following the genotoxic stress induced by radiation and revealed further insights in the radiation-sensitivity of the different lung cells. Finally, we provide cellular gene sets found to be induced in the different lung organoid cellular subsets after irradiation, which could be used as additional RT response and particularly senescence gene sets in future studies.
CONCLUSION: By establishing these free-floating LuOrgs for the investigation of cancer therapeutic approaches as a new and patient-oriented in vitro platform particularly in experimental radiooncology, not only a reduction in the number of experimental animals, but also an adequately and meaningfully replacement of corresponding animal experiments can be achieved.

Keywords:  Disease modeling; Genotoxic stress; Lung injury; Lung organoid; Radiation; Single cell RNAseq; iPSC

DOI:  https://doi.org/10.1186/s13287-024-04106-3
Int J Mol Sci. 2024 Nov 28. pii: 12789. [Epub ahead of print]25(23):

The Neuroprotective Effect of the X Protein of Orthobornavirus Bornaense Type 1 in Amyotrophic Lateral Sclerosis.

Jeflie Tournezy, Claire Léger, Bernard Klonjkowski, Daniel Gonzalez-Dunia, Marion Szelechowski, André Garenne, Stéphane Mathis, Stéphanie Chevallier, Gwendal Le Masson.

  In amyotrophic lateral sclerosis (ALS), early mitochondrial dysfunction may contribute to progressive motor neuron loss. Remarkably, the ectopic expression of the Orthobornavirus bornaense type 1 (BoDV-1) X protein in mitochondria blocks apoptosis and protects neurons from degeneration. Therefore, this study examines the neuroprotective effects of X protein in an ALS mouse model. We first tested in vitro the effect of the X-derived peptide (PX3) on motoneurons primary cultures of SOD1G93A mice. The total intracellular adenosine triphosphate (ATP) content was measured after incubation of the peptide. We next tested in vivo the intramuscular injection of X protein using a canine viral vector (CAV2-X) and PX3 intranasal administrations in SOD1G93A mice. Disease onset and progression were assessed through rotarod performance, functional motor unit analysis via electrophysiology, and motor neuron survival by immunohistochemistry. The results showed that in vitro PX3 restored the ATP level in SOD1G93A motor neurons. In vivo, treated mice demonstrated better motor performance, preserved motor units, and higher motor neuron survival. Although life expectancy was not extended in this severe mouse model of motor neuron degeneration, the present findings clearly demonstrate the neuroprotective potential of X protein in a model of ALS. We are convinced that further studies may improve the therapeutic impact of X protein with optimized administration methods.

Keywords:  ALS; BoDV-1; SOD1G93A mice; X protein; mitochondria

DOI:  https://doi.org/10.3390/ijms252312789
Gigascience. 2024 Jan 02. pii: giae100. [Epub ahead of print]13

A dataset profiling the multiomic landscape of the prefrontal cortex in amyotrophic lateral sclerosis.

Fabian Hausmann, Lucas Caldi Gomes, Sonja Hänzelmann, Robin Khatri, Sergio Oller, Marie Gebelin, Mojan Parvaz, Laura Tzeplaeff, Laura Pasetto, Qihui Zhou, Pavol Zelina, Dieter Edbauer, R Jeroen Pasterkamp, Hubert Rehrauer, Ralph Schlapbach, Christine Carapito, Valentina Bonetto, Stefan Bonn, Paul Lingor.

  Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease, which still lacks effective disease-modifying therapies. Similar to other neurodegenerative disorders, such as Alzheimer and Parkinson disease, ALS pathology is presumed to propagate over time, originating from the motor cortex and spreading to other cortical regions. Exploring early disease stages is crucial to understand the causative molecular changes underlying the pathology. For this, we sampled human postmortem prefrontal cortex (PFC) tissue from Brodmann area 6, an area that exhibits only moderate pathology at the time of death, and performed a multiomic analysis of 51 patients with sporadic ALS and 50 control subjects. To compare sporadic disease to genetic ALS, we additionally analyzed PFC tissue from 4 transgenic ALS mouse models (C9orf72-, SOD1-, TDP-43-, and FUS-ALS) using the same methods. This multiomic data resource includes transcriptome, small RNAome, and proteome data from female and male samples, aimed at elucidating early and sex-specific ALS mechanisms, biomarkers, and drug targets.

Keywords:  amyotrophic lateral sclerosis; early disease mechanisms; multiomics analysis; neurodegeneration; prefrontal cortex

DOI:  https://doi.org/10.1093/gigascience/giae100
Int J Mol Sci. 2024 Nov 29. pii: 12855. [Epub ahead of print]25(23):

Mitochondrial Dynamics in Brain Cells During Normal and Pathological Aging.

Vladimir S Sukhorukov, Tatiana I Baranich, Anna V Egorova, Anastasia V Akateva, Kseniia M Okulova, Maria S Ryabova, Krisitina A Skvortsova, Oscar V Dmitriev, Natalia M Mudzhiri, Dmitry N Voronkov, Sergey N Illarioshkin.

  Mitochondrial dynamics significantly play a major role in the pathogenesis of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. The dysregulation of mitochondrial biogenesis and function, characterized by impaired fission and fusion processes mediated by a number of proteins, in particular, Drp1, Mfn1, Mfn2, Opa1, and PGC-1α, contributes to neuronal vulnerability and degeneration. Insufficient mitophagy and disrupted mitochondrial transport exacerbate oxidative stress and neurotoxicity. Emerging therapeutic strategies that target mitochondrial dynamics, including various pharmacological agents, demonstrate potential for restoring mitochondrial balance and enhancing neuroprotection. This growing body of research underscores the importance of mitochondrial health in developing effective interventions for neurodegenerative conditions. This review highlights well-established links between the disruption of mitochondrial dynamics and the development of neurodegenerative processes. We also discuss different therapeutic strategies that target mitochondrial function in neurons that have been proposed as perspective neuroprotective treatments.

Keywords:  mitochondrial dynamics; mitophagy; neurodegeneration; neuroprotection

DOI:  https://doi.org/10.3390/ijms252312855
Elife. 2024 Dec 19. pii: RP91083. [Epub ahead of print]12

Intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism.

Bernd K Gilsbach, Franz Y Ho, Benjamin Riebenbauer, Xiaojuan Zhang, Giambattista Guaitoli, Arjan Kortholt, Christian Johannes Gloeckner.

  The Parkinson's disease (PD)-linked protein Leucine-Rich Repeat Kinase 2 (LRRK2) consists of seven domains, including a kinase and a Roc G domain. Despite the availability of several high-resolution structures, the dynamic regulation of its unique intramolecular domain stack is nevertheless still not well understood. By in-depth biochemical analysis, assessing the Michaelis-Menten kinetics of the Roc G domain, we have confirmed that LRRK2 has, similar to other Roco protein family members, a KM value of LRRK2 that lies within the range of the physiological GTP concentrations within the cell. Furthermore, the R1441G PD variant located within a mutational hotspot in the Roc domain showed an increased catalytic efficiency. In contrast, the most common PD variant G2019S, located in the kinase domain, showed an increased KM and reduced catalytic efficiency, suggesting a negative feedback mechanism from the kinase domain to the G domain. Autophosphorylation of the G1+2 residue (T1343) in the Roc P-loop motif is critical for this phosphoregulation of both the KM and the kcat values of the Roc-catalyzed GTP hydrolysis, most likely by changing the monomer-dimer equilibrium. The LRRK2 T1343A variant has a similar increased kinase activity in cells compared to G2019S and the double mutant T1343A/G2019S has no further increased activity, suggesting that T1343 is crucial for the negative feedback in the LRRK2 signaling cascade. Together, our data reveal a novel intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism. Interestingly, PD mutants differently change the kinetics of the GTPase cycle, which might in part explain the difference in penetrance of these mutations in PD patients.

Keywords:  GTPase; LRRK2; Michaelis–Menten kinetics; PD; biochemistry; chemical biology; negative feedback loop; none; parkinson's disease

DOI:  https://doi.org/10.7554/eLife.91083
Mol Neurodegener. 2024 Dec 18. 19(1): 97

The UFMylation pathway is impaired in Alzheimer's disease.

Tingxiang Yan, Michael G Heckman, Emily C Craver, Chia-Chen Liu, Bailey D Rawlinson, Xue Wang, Melissa E Murray, Dennis W Dickson, Nilufer Ertekin-Taner, Zhenkun Lou, Guojun Bu, Wolfdieter Springer, Fabienne C Fiesel.

   BACKGROUND: Alzheimer's disease (AD) is characterized by the presence of neurofibrillary tangles made of hyperphosphorylated tau and senile plaques composed of beta-amyloid. These pathognomonic deposits have been implicated in the pathogenesis, although the molecular mechanisms and consequences remain undetermined. UFM1 is an important, but understudied ubiquitin-like protein that is covalently attached to substrates. UFMylation has recently been identified as major modifier of tau aggregation upon seeding in experimental models. However, potential alterations of the UFM1 pathway in human AD brain have not been investigated yet.
METHODS: Here we used frontal and temporal cortex samples from individuals with or without AD to measure the protein levels of the UFMylation pathway in human brain. We used multivariable regression analyses followed by Bonferroni correction for multiple testing to analyze associations of the UFMylation pathway with neuropathological characteristics, primary biochemical measurements of tau and additional biochemical markers from the same cases. We further studied associations of the UFMylation cascade with cellular stress pathways using Spearman correlations with bulk RNAseq expression data and functionally validated these interactions using gene-edited neurons that were generated by CRISPR-Cas9.
RESULTS: Compared to controls, human AD brain had increased protein levels of UFM1. Our data further indicates that this increase mainly reflects conjugated UFM1 indicating hyperUFMylation in AD. UFMylation was strongly correlated with pathological tau in both AD-affected brain regions. In addition, we found that the levels of conjugated UFM1 were negatively correlated with soluble levels of the deUFMylation enzyme UFSP2. Functional analysis of UFM1 and/or UFSP2 knockout neurons revealed that the DNA damage response as well as the unfolded protein response are perturbed by changes in neuronal UFM1 signaling.
CONCLUSIONS: There are marked changes in the UFMylation pathway in human AD brain. These changes are significantly associated with pathological tau, supporting the idea that the UFMylation cascade might indeed act as a modifier of tau pathology in human brain. Our study further nominates UFSP2 as an attractive target to reduce the hyperUFMylation observed in AD brain but also underscores the critical need to identify risks and benefits of manipulating the UFMylation pathway as potential therapeutic avenue for AD.

Keywords:  Alzheimer’s disease; Brain; Tau; UFM1; UFMylation; UFSP2

DOI:  https://doi.org/10.1186/s13024-024-00784-y
Mol Ther. 2024 Dec 12. pii: S1525-0016(24)00815-3. [Epub ahead of print]

IL-1ra and CCL5, but not IL-10, are promising targets for treating SMA astrocyte-driven pathology.

Reilly L Allison, Cecelia C Mangione, Mya Suneja, Jessica Gawrys, Brendan M Melvin, Natalya Belous, Megan LaCroix, Matthew Harmelink, Barrington G Burnett, Allison D Ebert.

Spinal muscular atrophy (SMA) is a pediatric genetic disorder characterized by the loss of spinal cord motor neurons. Although the mechanisms underlying motor neuron loss are not clear, current data suggest that glial cells contribute to disease pathology. We have previously found that SMA astrocytes drive microglial activation and motor neuron loss potentially through the upregulation of NFkB-mediated pro-inflammatory cytokines. In this study, we tested the ability of neutralizing C-C motif chemokine ligand 5 (CCL5) while increasing either interleukin 10 (IL-10) or IL-1 receptor antagonist (IL-1ra) to reduce the pro-inflammatory phenotype of SMA astrocytes. While IL-10 was ineffective, IL-1ra ameliorated SMA astrocyte-driven glial activation and motor neuron loss in iPSC-derived cultures in vitro. In vivo AAV5 delivered IL-1ra overexpression and miR-30 shRNA knockdown of CCL5 had modest but significant improvements on lifespan, weight gain, motor neuron number, and motor function of SMNΔ7 mice. Together these data identify IL-1ra and CCL5 as possible therapeutic targets for SMA and highlight the importance of glial-targeted therapeutics for neurodegenerative disease.

DOI: https://doi.org/10.1016/j.ymthe.2024.12.016
Integr Psychol Behav Sci. 2024 Dec 19. 59(1): 1

Consciousness and the Axon Initial Segment.

Majid Beshkar.

  According to the QBIT theory, consciousness depends on the emergence of macroscopic coherence in a specific intracellular substrate which registers and processes sensory information. This occurs in a particular neuronal compartment called the axon initial segment which has unique properties not found in other neuronal segments. These unique properties allow the integration of synaptic inputs, amplification of sensory signals, and spontaneous emergence of coherence which is necessary for conscious perception.

Keywords:  Axon initial segment; Brain; Consciousness

DOI:  https://doi.org/10.1007/s12124-024-09883-3
Radiol Case Rep. 2025 Feb;20(2): 1121-1123

Amyotrophic lateral sclerosis in a tricenarian female.

Anshul Sood, Gaurav Vedprakash Mishra, Pallavi Kar, Shreya Khandelwal, Shubhi Gaur, Nishtha Manuja.

  Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by the progressive degeneration of the upper and lower motor neurons. This disease is mostly observed in patients of the 6th decade or above, and it is extremely rare to observe this pathology in patients less than 50 years of age. This manuscript depicts the magnetic resonance imaging findings of ALS showing a wine glass sign in a 31-year-old female from a rural area with complaints of progressive limb weakness and muscle wasting.

Keywords:  ALS; Female; MRI; Radiology; Wine glass sign

DOI:  https://doi.org/10.1016/j.radcr.2024.10.153
J Cell Sci. 2024 Dec 15. pii: jcs263470. [Epub ahead of print]137(24):

Phase separation of microtubule-binding proteins - implications for neuronal function and disease.

Daisy Duan, Anthony J Koleske.

  Protein liquid-liquid phase separation (LLPS) is driven by intrinsically disordered regions and multivalent binding domains, both of which are common features of diverse microtubule (MT) regulators. Many in vitro studies have dissected the mechanisms by which MT-binding proteins (MBPs) regulate MT nucleation, stabilization and dynamics, and investigated whether LLPS plays a role in these processes. However, more recent in vivo studies have focused on how MBP LLPS affects biological functions throughout neuronal development. Dysregulation of MBP LLPS can lead to formation of aggregates - an underlying feature in many neurodegenerative diseases - such as the tau neurofibrillary tangles present in Alzheimer's disease. In this Review, we highlight progress towards understanding the regulation of MT dynamics through the lens of phase separation of MBPs and associated cytoskeletal regulators, from both in vitro and in vivo studies. We also discuss how LLPS of MBPs regulates neuronal development and maintains homeostasis in mature neurons.

Keywords:  Microtubule-binding proteins; Microtubules; Neurodegeneration; Neurons; Phase separation

DOI:  https://doi.org/10.1242/jcs.263470
Int J Mol Sci. 2024 Dec 09. pii: 13224. [Epub ahead of print]25(23):

Discovery of a Small Molecule with an Inhibitory Role for RAB11.

Camille Lempicki, Julian Milosavljevic, Christian Laggner, Simone Tealdi, Charlotte Meyer, Gerd Walz, Konrad Lang, Carlo Cosimo Campa, Tobias Hermle.

  RAB11, a pivotal RabGTPase, regulates essential cellular processes such as endocytic recycling, exocytosis, and autophagy. The protein was implicated in various human diseases, including cancer, neurodegenerative disorders, viral infections, and podocytopathies. However, a small-molecular inhibitor is lacking. The complexity and workload associated with potential assays make conducting large-scale screening for RAB11 challenging. We employed a tiered approach for drug discovery, utilizing deep learning-based computational screening to preselect compounds targeting a specific pocket of RAB11 protein with experimental validation by an in vitro platform reflecting RAB11 activity through the exocytosis of GFP. Further validation included the exposure of Drosophila by drug feeding. In silico pre-screening identified 94 candidates, of which 9 were confirmed using our in vitro platform for Rab11 activity. Focusing on compounds with high potency, we assessed autophagy, which independently requires RAB11, and validated three of these compounds. We further analyzed the dose-response relationship, observing a biphasic, potentially hormetic effect. Two candidate compounds specifically caused a shift in Rab11 vesicles to the cell periphery, without significant impact on Rab5 or Rab7. Drosophila larvae exposed to another candidate compound with predicted oral bioavailability exhibited minimal toxicity, subcellular dispersal of endogenous Rab11, and a decrease in RAB11-dependent nephrocyte function, further supporting an inhibitory role. Taken together, the combination of computational screening and experimental validation allowed the identification of small molecules that modify the function of Rab11. This discovery may further open avenues for treating RAB11-associated disorders.

Keywords:  Drosophila nephrocytes; Rab11; drug discovery; endocytosis; high-throughput screening; machine learning; virtual screening

DOI:  https://doi.org/10.3390/ijms252313224
Cells. 2024 Nov 23. pii: 1945. [Epub ahead of print]13(23):

Neuronal Cell Rearrangement During Aging: Antioxidant Compounds as a Potential Therapeutic Approach.

Erjola Bej, Patrizia Cesare, Michele d'Angelo, Anna Rita Volpe, Vanessa Castelli.

  Aging is a natural process that leads to time-related changes and a decrease in cognitive abilities, executive functions, and attention. In neuronal aging, brain cells struggle to respond to oxidative stress. The structure, function, and survival of neurons can be mediated by different pathways that are sensitive to oxidative stress and age-related low-energy states. Mitochondrial impairment is one of the most noticeable signs of brain aging. Damaged mitochondria are thought to be one of the main causes that feed the inflammation related to aging. Also, protein turnover is involved in age-related impairments. The brain, due to its high oxygen usage, is particularly susceptible to oxidative damage. This review explores the mechanisms underlying neuronal cell rearrangement during aging, focusing on morphological changes that contribute to cognitive decline and increased susceptibility to neurodegenerative diseases. Potential therapeutic approaches are discussed, including the use of antioxidants (e.g., Vitamin C, Vitamin E, glutathione, carotenoids, quercetin, resveratrol, and curcumin) to mitigate oxidative damage, enhance mitochondrial function, and maintain protein homeostasis. This comprehensive overview aims to provide insights into the cellular and molecular processes of neuronal aging and highlight promising therapeutic avenues to counteract age-related neuronal deterioration.

Keywords:  ROS; antioxidants; brain; mitochondrial dysfunction; neurodegeneration; organelles; oxidative damage

DOI:  https://doi.org/10.3390/cells13231945
Science. 2024 Dec 20. 386(6728): 1349-1350

Aged neurons don't register energy need.

Deniz Bingul, Scott F Owen.

Neuronal activity and mitochondrial gene expression become decoupled in aged mice.

DOI: https://doi.org/10.1126/science.adu4935
ACS Chem Neurosci. 2024 Dec 18.

Neurochemical and Morphological Comparisons of Motor Nerve Organoids and Spinal-Cord Explants.

Shannon E Murphy, Amanda C Sullivan-Weiss, Chen H Sirois, Stanislav S Rubakhin, Hyunjoon Kong, Martha U Gillette, Jonathan V Sweedler.

  Organoids are multicellular structures formed in vitro from populations of individual cells allowing modeling of structural and functional aspects of organs and tissues in normal and diseased states. They offer unique opportunities to model and treat disease. Using a mouse embryonic stem cell line, we have cultured organoids that express markers of spinal cord motor neurons as well as motor neurons found within the peripheral nervous system. The morphology and select neurotransmitter content of the organoids and spinal cord explants were compared at different developmental time points. We found indications of maturation in the organoids over time, mirrored by similar trends in the spinal cord explants. Although the organoids contained the same neurotransmitters as the spinal cord explants, the developmental changes of these neurotransmitter levels were less marked in organoids. Given these differences, further work is required to optimize organoid growth conditions to better reproduce in vivo models when using organoids to study development.

Keywords:  capillary electrophoresis-mass spectrometry; development; morphology; neurotransmitter; organoid; spinal cord explants

DOI:  https://doi.org/10.1021/acschemneuro.4c00625