bims-axbals 2024-07-28 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2024–07–28
twelve papers selected by
TJ Krzystek, ALS Therapy Development Institute

Using ALS to understand profilin 1's diverse roles in cellular physiology.
ALS-linked VapB P56S mutation alters neuronal mitochondrial turnover at the synapse.
AAV-NRIP gene therapy ameliorates motor neuron degeneration and muscle atrophy in ALS model mice.
Zfp106 binds to G-quadruplex RNAs and inhibits RAN translation and formation of RNA foci caused by G4C2 repeats.
Benzoxazole-derivatives enhance progranulin expression and reverse the aberrant lysosomal proteome caused by GRN haploinsufficiency.
A novel digital tool for detection and monitoring of amyotrophic lateral sclerosis motor impairment and progression via keystroke dynamics.
Limitations of human brain organoids to study neurodegenerative diseases: a manual to survive.
Copper toxicity and deficiency: the vicious cycle at the core of protein aggregation in ALS.
Therapeutics Targeting Skeletal Muscle in Amyotrophic Lateral Sclerosis.
Tofersen decreases neurofilament levels supporting the pathogenesis of the SOD1 p.D91A variant in amyotrophic lateral sclerosis patients.
An ankyrin G-binding motif mediates TRAAK periodic localization at axon initial segments of hippocampal pyramidal neurons.
Lipidome profiling of neutrophil-derived extracellular vesicles unveils their contribution to the ensemble of synovial fluid-derived extracellular vesicles during joint inflammation.

Cytoskeleton (Hoboken). 2024 Jul 26.

Using ALS to understand profilin 1's diverse roles in cellular physiology.

Halli L Lindamood, Tatiana M Liu, Tracy-Ann Read, Eric A Vitriol.

  Profilin is an actin monomer-binding protein whose role in actin polymerization has been studied for nearly 50 years. While its principal biochemical features are now well understood, many questions remain about how profilin controls diverse processes within the cell. Dysregulation of profilin has been implicated in a broad range of human diseases, including neurodegeneration, inflammatory disorders, cardiac disease, and cancer. For example, mutations in the profilin 1 gene (PFN1) can cause amyotrophic lateral sclerosis (ALS), although the precise mechanisms that drive neurodegeneration remain unclear. While initial work suggested proteostasis and actin cytoskeleton defects as the main pathological pathways, multiple novel functions for PFN1 have since been discovered that may also contribute to ALS, including the regulation of nucleocytoplasmic transport, stress granules, mitochondria, and microtubules. Here, we will review these newly discovered roles for PFN1, speculate on their contribution to ALS, and discuss how defects in actin can contribute to these processes. By understanding profilin 1's involvement in ALS pathogenesis, we hope to gain insight into this functionally complex protein with significant influence over cellular physiology.

Keywords:  actin; amyotrophic lateral sclerosis; microtubules; mitochondria; nucleocytoplasmic transport; profilin; stress granules

DOI:  https://doi.org/10.1002/cm.21896
J Neurosci. 2024 Jul 25. pii: e0879242024. [Epub ahead of print]

ALS-linked VapB P56S mutation alters neuronal mitochondrial turnover at the synapse.

Hiu-Tung C Wong, Angelica E Lang, Chris Stein, Catherine M Drerup.

Mitochondrial population maintenance in neurons is essential for neuron function and survival. Contact sites between mitochondria and the endoplasmic reticulum (ER) are poised to regulate mitochondrial homeostasis in neurons. These contact sites can function to facilitate transfer of calcium and lipids between the organelles and have been shown to regulate aspects of mitochondrial fission and fusion dynamics. VapB is an ER membrane protein present at a subset of ER-mitochondria contact sites. Mutations in VapB cause neurodegenerative disease. Specifically, a proline-to-serine mutation at amino acid 56 (P56S), correlates with susceptibility to amyotrophic lateral sclerosis (ALS) type 8. Given the relationship between failed mitochondrial health and neurodegenerative disease, we investigated the function of VapB in mitochondrial population maintenance. We demonstrate that transgenic expression of VapBP56S in zebrafish larvae (sex undetermined) increased mitochondrial biogenesis, causing increased mitochondrial population size in the axon terminal. Expression of wild type VapB did not alter biogenesis but, instead, increased mitophagy in the axon terminal. Using genetic manipulations to independently increase mitochondrial biogenesis in zebrafish neurons, we show that biogenesis is normally balanced by mitophagy to maintain a constant mitochondrial population size. VapBP56S transgenics fail to increase mitophagy to compensate for the increase in mitochondrial biogenesis, suggesting an impaired mitophagic response. Finally, using a synthetic ER-mitochondria tether, we show that VapB's function in mitochondrial turnover is likely independent of ER-mitochondrial tethering by contact sites. Our findings demonstrate that VapB can control mitochondrial turnover in the axon terminal, and this function is altered by the P56S ALS-linked mutation.Significance statement Mitochondrial population dysfunction is tightly tied to neurodegenerative diseases, including ALS. Maintenance of the mitochondrial population in neurons requires the birth of new mitochondria and the degradation of damaged organelles. ER-mitochondrial contact site proteins are in a position to regulate both processes in neurons. Our work demonstrates that an ALS-associated mutation in the contact site protein VapB disrupts both processes, identifying VapB as a mediator of regulated mitochondrial turnover to maintain a steady-state mitochondrial population.

DOI: https://doi.org/10.1523/JNEUROSCI.0879-24.2024
Skelet Muscle. 2024 Jul 24. 14(1): 17

AAV-NRIP gene therapy ameliorates motor neuron degeneration and muscle atrophy in ALS model mice.

Hsin-Hsiung Chen, Hsin-Tung Yeo, Yun-Hsin Huang, Li-Kai Tsai, Hsing-Jung Lai, Yeou-Ping Tsao, Show-Li Chen.

   BACKGROUND: Amyotrophic lateral sclerosis (ALS) is characterized by progressive motor neuron (MN) degeneration, leading to neuromuscular junction (NMJ) dismantling and severe muscle atrophy. The nuclear receptor interaction protein (NRIP) functions as a multifunctional protein. It directly interacts with calmodulin or α-actinin 2, serving as a calcium sensor for muscle contraction and maintaining sarcomere integrity. Additionally, NRIP binds with the acetylcholine receptor (AChR) for NMJ stabilization. Loss of NRIP in muscles results in progressive motor neuron degeneration with abnormal NMJ architecture, resembling ALS phenotypes. Therefore, we hypothesize that NRIP could be a therapeutic factor for ALS.
METHODS: We used SOD1 G93A mice, expressing human SOD1 with the ALS-linked G93A mutation, as an ALS model. An adeno-associated virus vector encoding the human NRIP gene (AAV-NRIP) was generated and injected into the muscles of SOD1 G93A mice at 60 days of age, before disease onset. Pathological and behavioral changes were measured to evaluate the therapeutic effects of AAV-NRIP on the disease progression of SOD1 G93A mice.
RESULTS: SOD1 G93A mice exhibited lower NRIP expression than wild-type mice in both the spinal cord and skeletal muscle tissues. Forced NRIP expression through AAV-NRIP intramuscular injection was observed in skeletal muscles and retrogradely transduced into the spinal cord. AAV-NRIP gene therapy enhanced movement distance and rearing frequencies in SOD1 G93A mice. Moreover, AAV-NRIP increased myofiber size and slow myosin expression, ameliorated NMJ degeneration and axon terminal denervation at NMJ, and increased the number of α-motor neurons (α-MNs) and compound muscle action potential (CMAP) in SOD1 G93A mice.
CONCLUSIONS: AAV-NRIP gene therapy ameliorates muscle atrophy, motor neuron degeneration, and axon terminal denervation at NMJ, leading to increased NMJ transmission and improved motor functions in SOD1 G93A mice. Collectively, AAV-NRIP could be a potential therapeutic drug for ALS.

Keywords:  AAV; ALS; Gene therapy; Motor neuron; Muscle; NRIP; Neuromuscular junction; SOD1 G93A

DOI:  https://doi.org/10.1186/s13395-024-00349-z
Proc Natl Acad Sci U S A. 2024 Jul 30. 121(31): e2220020121

Zfp106 binds to G-quadruplex RNAs and inhibits RAN translation and formation of RNA foci caused by G4C2 repeats.

Barbara Celona, Sally E Salomonsson, Haifan Wu, Bobo Dang, Huong T Kratochvil, Claire D Clelland, William F DeGrado, Brian L Black.

  Expansion of intronic GGGGCC repeats in the C9orf72 gene causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Transcription of the expanded repeats results in the formation of RNA-containing nuclear foci and altered RNA metabolism. In addition, repeat-associated non-AUG (RAN) translation of the expanded GGGGCC-repeat sequence results in the production of highly toxic dipeptide-repeat (DPR) proteins. GGGGCC repeat-containing transcripts form G-quadruplexes, which are associated with formation of RNA foci and RAN translation. Zfp106, an RNA-binding protein essential for motor neuron survival in mice, suppresses neurotoxicity in a Drosophila model of C9orf72 ALS. Here, we show that Zfp106 inhibits formation of RNA foci and significantly reduces RAN translation caused by GGGGCC repeats in cultured mammalian cells, and we demonstrate that Zfp106 coexpression reduces the levels of DPRs in C9orf72 patient-derived cells. Further, we show that Zfp106 binds to RNA G-quadruplexes and causes a conformational change in the G-quadruplex structure formed by GGGGCC repeats. Together, these data demonstrate that Zfp106 suppresses the formation of RNA foci and DPRs caused by GGGGCC repeats and suggest that the G-quadruplex RNA-binding function of Zfp106 contributes to its suppression of GGGGCC repeat-mediated cytotoxicity.

Keywords:  C9orf72; G-quadruplex; RAN translation; RNA-binding protein; amyotrophic lateral sclerosis

DOI:  https://doi.org/10.1073/pnas.2220020121
Nat Commun. 2024 Jul 20. 15(1): 6125

Benzoxazole-derivatives enhance progranulin expression and reverse the aberrant lysosomal proteome caused by GRN haploinsufficiency.

Rachel Tesla, Charlotte Guhl, Gordon C Werthmann, Danielle Dixon, Basar Cenik, Yesu Addepalli, Jue Liang, Daniel M Fass, Zachary Rosenthal, Stephen J Haggarty, Noelle S Williams, Bruce A Posner, Joseph M Ready, Joachim Herz.

Heterozygous loss-of-function mutations in the GRN gene are a major cause of hereditary frontotemporal dementia. The mechanisms linking frontotemporal dementia pathogenesis to progranulin deficiency are not well understood, and there is currently no treatment. Our strategy to prevent the onset and progression of frontotemporal dementia in patients with GRN mutations is to utilize small molecule positive regulators of GRN expression to boost progranulin levels from the remaining functional GRN allele, thus restoring progranulin levels back to normal within the brain. This work describes a series of blood-brain-barrier-penetrant small molecules which significantly increase progranulin protein levels in human cellular models, correct progranulin protein deficiency in Grn+/- mouse brains, and reverse lysosomal proteome aberrations, a phenotypic hallmark of frontotemporal dementia, more efficiently than the previously described small molecule suberoylanilide hydroxamic acid. These molecules will allow further elucidation of the cellular functions of progranulin and its role in frontotemporal dementia and will also serve as lead structures for further drug development.

DOI: https://doi.org/10.1038/s41467-024-50076-8
Sci Rep. 2024 Jul 22. 14(1): 16851

A novel digital tool for detection and monitoring of amyotrophic lateral sclerosis motor impairment and progression via keystroke dynamics.

Alejandro Acien, Narghes Calcagno, Katherine M Burke, Ijah Mondesire-Crump, Ashley A Holmes, Sri Mruthik, Ben Goldy, Janina E Syrotenko, Zoe Scheier, Amrita Iyer, Alison Clark, Mackenzie Keegan, Yoshiteru Ushirogawa, Atsushi Kato, Taku Yasuda, Amir Lahav, Satoshi Iwasaki, Mark Pascarella, Stephen A Johnson, Teresa Arroyo-Gallego, James D Berry.

  Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative condition leading to progressive muscle weakness, atrophy, and ultimately death. Traditional ALS clinical evaluations often depend on subjective metrics, making accurate disease detection and monitoring disease trajectory challenging. To address these limitations, we developed the nQiALS toolkit, a machine learning-powered system that leverages smartphone typing dynamics to detect and track motor impairment in people with ALS. The study included 63 ALS patients and 30 age- and sex-matched healthy controls. We introduce the three core components of this toolkit: the nQiALS-Detection, which differentiated ALS from healthy typing patterns with an AUC of 0.89; the nQiALS-Progression, which separated slow and fast progression at specific thresholds with AUCs ranging between 0.65 and 0.8; and the nQiALS-Fine Motor, which identified subtle progression in fine motor dysfunction, suggesting earlier prediction than the state-of-the-art assessment. Together, these tools represent an innovative approach to ALS assessment, offering a complementary, objective metric to traditional clinical methods and which may reshape our understanding and monitoring of ALS progression.

Keywords:  ALSFRS-R; Amyotrophic lateral sclerosis; Digital biomarkers; Fine motor; Keystroke dynamics; Machine learning; Motor impairment

DOI:  https://doi.org/10.1038/s41598-024-67940-8
Front Cell Neurosci. 2024 ;18 1419526

Limitations of human brain organoids to study neurodegenerative diseases: a manual to survive.

Nerea Urrestizala-Arenaza, Sonia Cerchio, Fabio Cavaliere, Chiara Magliaro.



Keywords:  Alzheimer’s disease; Parkinson’s disease; amyotrophic lateral disease; brain organoids; neurodegenerative diseases

DOI:  https://doi.org/10.3389/fncel.2024.1419526
Front Mol Neurosci. 2024 ;17 1408159

Copper toxicity and deficiency: the vicious cycle at the core of protein aggregation in ALS.

Jin-Hong Min, Heela Sarlus, Robert A Harris.

  The pathophysiology of ALS involves many signs of a disruption in copper homeostasis, with both excess free levels and functional deficiency likely occurring simultaneously. This is crucial, as many important physiological functions are performed by cuproenzymes. While it is unsurprising that many ALS symptoms are related to signs of copper deficiency, resulting in vascular, antioxidant system and mitochondrial oxidative respiration deficiencies, there are also signs of copper toxicity such as ROS generation and enhanced protein aggregation. We discuss how copper also plays a key role in proteostasis and interacts either directly or indirectly with many of the key aggregate-prone proteins implicated in ALS, such as TDP-43, C9ORF72, SOD1 and FUS as well as the effect of their aggregation on copper homeostasis. We suggest that loss of cuproprotein function is at the core of ALS pathology, a condition that is driven by a combination of unbound copper and ROS that can either initiate and/or accelerate protein aggregation. This could trigger a positive feedback cycle whereby protein aggregates trigger the aggregation of other proteins in a chain reaction that eventually captures elements of the proteostatic mechanisms in place to counteract them. The end result is an abundance of aggregated non-functional cuproproteins and chaperones alongside depleted intracellular copper stores, resulting in a general lack of cuproenzyme function. We then discuss the possible aetiology of ALS and illustrate how strong risk factors including environmental toxins such as BMAA and heavy metals can functionally behave to promote protein aggregation and disturb copper metabolism that likely drives this vicious cycle in sporadic ALS. From this synthesis, we propose restoration of copper balance using copper delivery agents in combination with chaperones/chaperone mimetics, perhaps in conjunction with the neuroprotective amino acid serine, as a promising strategy in the treatment of this incurable disease.

Keywords:  ALS; C9ORF72; SOD1; TDP-43; aggregate; copper; neurodegeneration; protein

DOI:  https://doi.org/10.3389/fnmol.2024.1408159
Biomolecules. 2024 Jul 22. pii: 878. [Epub ahead of print]14(7):

Therapeutics Targeting Skeletal Muscle in Amyotrophic Lateral Sclerosis.

Jinghui Gao, Elijah Sterling, Rachel Hankin, Aria Sikal, Yao Yao.

  Amyotrophic lateral sclerosis (ALS) is a complex neuromuscular disease characterized by progressive motor neuron degeneration, neuromuscular junction dismantling, and muscle wasting. The pathological and therapeutic studies of ALS have long been neurocentric. However, recent insights have highlighted the significance of peripheral tissue, particularly skeletal muscle, in disease pathology and treatment. This is evidenced by restricted ALS-like muscle atrophy, which can retrogradely induce neuromuscular junction and motor neuron degeneration. Moreover, therapeutics targeting skeletal muscles can effectively decelerate disease progression by modulating muscle satellite cells for muscle repair, suppressing inflammation, and promoting the recovery or regeneration of the neuromuscular junction. This review summarizes and discusses therapeutic strategies targeting skeletal muscles for ALS treatment. It aims to provide a comprehensive reference for the development of novel therapeutics targeting skeletal muscles, potentially ameliorating the progression of ALS.

Keywords:  amyotrophic lateral sclerosis (ALS); inflammation; muscle satellite cells (MuSCs); neuromuscular junction (NMJ); skeletal muscle

DOI:  https://doi.org/10.3390/biom14070878
Commun Med (Lond). 2024 Jul 25. 4(1): 150

Tofersen decreases neurofilament levels supporting the pathogenesis of the SOD1 p.D91A variant in amyotrophic lateral sclerosis patients.

Jochen H Weishaupt, Péter Körtvélyessy, Peggy Schumann, Ivan Valkadinov, Ute Weyen, Jasper Hesebeck-Brinckmann, Kanchi Weishaupt, Matthias Endres, Peter M Andersen, Martin Regensburger, Marie Dreger, Jan C Koch, Julian Conrad, Thomas Meyer.

BACKGROUND: Since the antisense oligonucleotide tofersen has recently become available for the treatment of amyotrophic lateral sclerosis (ALS) caused by mutations in SOD1, determining the causality of the over 230 SOD1 variants has become even more important. The most common SOD1 variant worldwide is p.D91A (c.272A > C), whose causality for ALS is contested when in a heterozygous state. The reason is the high allele frequency of SOD1D91A in Europe, exceeding 1% in Finno-Scandinavia.
METHODS: We present the clinical disease course and serum neurofilament light chain (NfL) results of treating 11 patients either homo- or heterozygous for the SOD1D91A allele for up to 16 months with tofersen.
RESULTS: Tofersen decreases serum neurofilament levels (sNFL), which are associated with the ALS progression rate, in the 6 ALS patients homozygous for SOD1D91A. We observe significantly lower sNfL levels in the 5 patients heterozygous for SOD1D91A. The results indicate that both mono- and bi-allelic SOD1D91A are causally relevant targets, with a possibly reduced effect size of SOD1D91Ahet.
CONCLUSIONS: The finding is relevant for decision making regarding tofersen treatment, patient counseling and inclusion of SOD1D91A patients in drug trials. As far as we are aware, the approach is conceptually new since it provides evidence for the causality of an ALS variant based on a biomarker response to gene-specific treatment.

DOI: https://doi.org/10.1038/s43856-024-00573-0
Proc Natl Acad Sci U S A. 2024 Jul 30. 121(31): e2310120121

An ankyrin G-binding motif mediates TRAAK periodic localization at axon initial segments of hippocampal pyramidal neurons.

Virginia Luque-Fernández, Sam K Vanspauwen, Arnaud Landra-Willm, Emil Arvedsen, Maïlys Besquent, Guillaume Sandoz, Hanne B Rasmussen.

  The axon initial segment (AIS) is a critical compartment in neurons. It converts postsynaptic input into action potentials that subsequently trigger information transfer to target neurons. This process relies on the presence of several voltage-gated sodium (NaV) and potassium (KV) channels that accumulate in high densities at the AIS. TRAAK is a mechanosensitive leak potassium channel that was recently localized to the nodes of Ranvier. Here, we uncover that TRAAK is also present in AISs of hippocampal and cortical neurons in the adult rat brain as well as in AISs of cultured rat hippocampal neurons. We show that the AIS localization is driven by a C-terminal ankyrin G-binding sequence that organizes TRAAK in a 190 nm spaced periodic pattern that codistributes with periodically organized ankyrin G. We furthermore uncover that while the identified ankyrin G-binding motif is analogous to known ankyrin G-binding motifs in NaV1 and KV7.2/KV7.3 channels, it was acquired by convergent evolution. Our findings identify TRAAK as an AIS ion channel that convergently acquired an ankyrin G-binding motif and expand the role of ankyrin G to include the nanoscale organization of ion channels at the AIS.

Keywords:  K2P4.1; KCNK4; STED; ankyrin G; axon initial segment

DOI:  https://doi.org/10.1073/pnas.2310120121
Biochim Biophys Acta Mol Cell Biol Lipids. 2024 Jul 20. pii: S1388-1981(24)00084-2. [Epub ahead of print]1869(7): 159534

Lipidome profiling of neutrophil-derived extracellular vesicles unveils their contribution to the ensemble of synovial fluid-derived extracellular vesicles during joint inflammation.

Laura Varela, Sanne Mol, Esther W Taanman-Kueter, Sarah E Ryan, Leonie S Taams, Esther de Jong, P René van Weeren, Chris H A van de Lest, Marca H M Wauben.

  The molecular signature of cell-derived extracellular vesicles (EVs) from synovial fluid (SF) offers insights into the cells and molecular processes associated with joint disorders and can be exploited to define biomarkers. The EV-signature is determined by cargo molecules and the lesser-studied lipid bilayer. We here investigated the lipidome of SF-EVs in inflamed joints derived from Rheumatoid Arthritis (RA) and Spondyloarthritis (SpA) patients, two autoimmune-driven joint diseases, and compared these signatures to the lipid profile of equine SF-EVs obtained during induced acute synovitis. Since neutrophils are primary SF-infiltrating cells during these inflammatory joint diseases, we also analyzed how inflammatory stimuli alter the lipidomic profile of human and equine neutrophil-derived EVs (nEVs) in vitro and how these signatures relate to the lipidome signatures of SF-EVs from inflamed joints. We identified neutrophil stimulation intensity-dependent changes in the lipidomic profile of nEVs with elevated presence of dihexosylceramide (lactosylceramide), phosphatidylserine, and phosphatidylethanolamine ether-linked lipid classes in human nEVs upon full neutrophil activation. In horses, levels of monohexosylceramide (glucosylceramide) increased instead of dihexosylceramide, indicating species-specific differences. The lipid profiles of RA and SpA SF-EVs were relatively similar and showed a relative resemblance with stimulated human nEVs. Similarly, the lipidome of equine synovitis-derived SF-EVs closer resembled the one of stimulated equine nEVs. Hence, lipidome profiling can provide insights into the contribution of nEVs to the heterogeneous pool of SF-EVs, deepening our understanding of inflammatory joint diseases and revealing molecular changes in joint homeostasis, which can lead to the development of more precise disease diagnosis and treatment strategies.

Keywords:  Arthritis; Equine; Extracellular vesicles; Human; Inflammation; Lipidomics; Neutrophils; Synovial fluid; Synovitis

DOI:  https://doi.org/10.1016/j.bbalip.2024.159534