Biology subjects

Tosolini, A. P.

Publications and source records attributed to Tosolini, A. P..

9 recordsLinked to original sources

bioRxiv2026

Schwann Cell-Specific TDP-43 Rescue Improves Peripheral Nerve Myelin Pathology Without Altering Motor Behaviour in a Mouse Model of ALS

Amyotrophic lateral sclerosis (ALS) is a terminal disease caused by motor neuron loss. Schwann cells, the myelinating cells of the peripheral nervous system, metabolically and structurally support neurons. ALS patients exhibit Schwann cell pathology, such as TDP-43 proteinopathy, therefore Schwann cell dysfunction may contribute to disease progression. Here, we have characterised myelinating Schwann cell pathology in a TDP-43Q331K (TDP-43) transgenic mouse model of ALS. We also crossed the floxxed TDP-43 mouse with a myelin protein zero (P0)-cre mouse to excise the transgene from Schwann cells alone (P0-cre/TDP-43) to assess rescue. Compared to wild-type (WT) littermates, 10 mo TDP-43 mice exhibited changes to myelin architecture, including loss of myelin binding proteins at the paranodes, decreased node of Ranvier length, and non-compact, degenerating myelin. In P0-cre/TDP-43 mice these myelin disruptions were rescued. However, this improved histology did not lead to a functional rescue, with both P0-cre/TDP-43 and TDP-43 mice exhibiting slowed sciatic nerve conduction and worsened motor behaviour. Further histological analyses revealed that Bungner Schwann cells, a subtype of Schwann cells triggered by neuronal injury, were activated in both TDP-43 and P0-cre/TDP-43 mice. Activation of Bungner Schwann cells can trigger damaging inflammation through the recruitment of macrophages, which can hinder motor and electrophysiological performance, potentially underpinning the lack of functional rescue in the P0-cre/TDP-43. We established that the rescue of Schwann cells indeed protects myelin in this ALS model, however understanding how Bungner Schwann cells exacerbate neuronal pathology is essential for developing effective therapeutics that can improve functional output. Significance StatementAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with no cure and limited treatments. Given that the average patient life expectancy is 3-5 years following diagnosis, finding novel treatment targets is of the utmost importance. Recent research has revealed that non-neuronal cells, such as Schwann cells, contribute to the disease, however the extent of their pathology remains elusive. Investigating Schwann cell and peripheral myelin pathology in ALS may lead to the identification of previously unrecognized disease mechanisms, opening novel avenues for therapeutic development. Identifying approaches through which to target glial and neuronal pathology concurrently would enable more holistic treatment of the various aspects of ALS pathobiology to improve patient outcomes.

neuroscience↗

bioRxiv2025

CNTF specifically slows down the axonal transport of signalling endosomes

Efficient axonal transport is essential for maintaining neuronal function, enabling the bidirectional delivery of diverse cargoes between the cell body and distal compartments. In the neuromuscular system, neurotrophic factors (NTFs) regulate motor neuron survival, function, and synaptic connectivity, in part, through retrograde trafficking of activated NTF-receptor complexes from the neuromuscular junction (NMJ) to the cell body. We recently demonstrated that brain-derived neurotrophic factor (BDNF) stimulation to muscles selectively enhances retrograde transport of signalling endosomes in fast, but not slow, motor neurons in vivo. Moreover, both axonal endosome transport and its BDNF-mediated regulation are disrupted in mouse models of diseases impacting motor neurons. Here, we examined whether additional NTFs, when applied to distal axon terminals, share this transport-modulating property. Through imaging sciatic nerves in anaesthetised mice, we tracked the in vivo dynamics of signalling endosomes in fast (FMN) and slow motor neurons (SMN) via intramuscular injections of a fluorescently conjugated, atoxic fragment of tetanus neurotoxin (HCT). HCT was co-administered with ciliary neurotrophic factor (CNTF), hepatocyte growth factor (HGF), neurturin (NRTN), or proBDNF - four growth factors with known effects on motor neurons. Compared to vehicle-treated controls, proBDNF, HGF, and NRTN, produced no detectable change in transport dynamics. In contrast, CNTF markedly reduced endosome speeds in both FMNs and SMNs, indicating remarkable selectivity of specific NTFs in the regulation of signalling endosome transport in motor neurons. Understanding this selectivity may aid the development of muscle-targeted NTF-based therapeutic strategies aimed at restoring axonal transport in neurodegenerative disease, peripheral neuropathy, and nerve injury. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/681259v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@10e4229org.highwire.dtl.DTLVardef@119c69aorg.highwire.dtl.DTLVardef@13dd629org.highwire.dtl.DTLVardef@b733ec_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Innervation and cargo-specific axonal transport impairments in FUS-ALS mice with gain and loss of function

Mutations in the RNA-binding protein FUS lead to nuclear depletion and cytoplasmic mislocalisation of the protein and cause amyotrophic lateral sclerosis (ALS). Using a novel FUS-ALS mouse model, we found that adult mutant mice develop loss of function transcriptomic alterations, along with aberrant cytoplasmic partitioning associated with translatome deficits. Neuromuscular junction innervation was selectively impaired in FUS-ALS females; however, reinnervation following sciatic nerve crush was equally perturbed in both sexes. Additionally, we observed cargo-specific axonal transport alterations, a process critical for neuronal maintenance. In vivo mitochondrial transport was impaired across FUS-ALS mice, whereas the transport of signalling endosomes was selectively disrupted in mutant females. Altogether, our findings identify broader and sex-dependent motor neuron dysfunction in FUS-ALS, emphasise the link between endosomal transport impairments and denervation in disease, and establish FUS-ALS mice as a valuable model for investigating early cellular impairments driving ALS pathology.

neuroscience↗

bioRxiv2025

Metabolic alterations in the absence of a detectable neuromuscular phenotype in novel genomically humanised SOD1A4V mice.

Amyotrophic lateral sclerosis (ALS) caused by mutation in superoxide dismutase 1 (SOD1) accounts for 15-30% of familial ALS and is typically autosomal dominant. How single base pair/amino acid changes in this small protein cause neurodegeneration is unknown. In North America, SOD1A4V is the most common familial ALS SOD1 mutation and results in an aggressive form of ALS. Here, we present a novel genomically humanised mouse model of SOD1A4V, in which the mouse Sod1 locus has been replaced by the human SOD1 gene, with intact genomic architecture of exons and introns, but bearing an A4V mutation. In agreement with previously reported human genomic knock-in mice, the phenotype is mild; however, transcriptomic and metabolomic profiling reveal significant dysregulation of glycolysis, the tricarboxylic acid (TCA) cycle, and lipid metabolism. These changes suggest an early bioenergetic imbalance that precedes neuromuscular impairment. Our findings support metabolic dysfunction as an early event in ALS pathogenesis. This freely available SOD1A4V model provides a valuable tool for studying ALS progression and identifying therapeutic targets for pre-symptomatic treatment. SUMMARY STATEMENTThis study describes the generation and analysis of novel genomically humanised SOD1A4V mice, revealing metabolic dysfunction through integrated multi-omic analyses, characterising a freely available potential pre-symptomatic ALS model for future research.

neuroscience↗

bioRxiv2025

Processivity and BDNF-dependent modulation of signalling endosome axonal transport are impaired in aged mice

A healthy nervous system is reliant upon an efficient transport network to deliver essential cargoes throughout the extensive and polarised architecture of neurons. The trafficking of cargoes, such as organelles and proteins, is particularly challenging within the long projections of neurons, which, in the case of axons, can be more than four orders of magnitude longer than cell bodies. It is therefore unsurprising that disruptions in axonal transport have been reported across neurological diseases. A decline in this essential process has also been identified in many aging models, perhaps compounding age-related neurodegeneration. Via intravital imaging, we recently determined that, despite a reduction in overall motility, the run speed and displacement of anterograde mitochondrial transport were unexpectedly enhanced in aged mouse peripheral nerves. Here, to determine how aging impacts a different axonal cargo, we evaluated in vivo trafficking of signalling endosomes in motor axons of mouse sciatic nerves from 3 to 22 months. Contrasting with mitochondria, we did not detect alterations in signalling endosome speed, but found a consistent rise in pausing that manifested after 18 months. We then treated muscles with brain-derived neurotrophic factor (BDNF), which regulates axonal transport of signalling endosomes in motor neurons; however, we observed no change in the processivity defect at 22 months, consistent with downregulation of the BDNF receptor TrkB at the neuromuscular junction. Together, these findings indicate that aging negatively impacts signalling endosome trafficking in motor axons likely through dampened BDNF signalling at the motor neuron-muscle interface. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC="FIGDIR/small/635507v1_ufig1.gif" ALT="Figure 1"> View larger version (84K): org.highwire.dtl.DTLVardef@d5fe63org.highwire.dtl.DTLVardef@13033c2org.highwire.dtl.DTLVardef@19621dcorg.highwire.dtl.DTLVardef@189121a_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

The node of Ranvier influences the in vivo axonal transport of mitochondria and signalling endosomes

Efficient long-range axonal transport is essential for maintaining neuronal function, and perturbations in this process underlie severe neurological diseases. We have previously demonstrated that signalling endosomes are transported in vivo at comparable speeds across motor neurons (MNs) innervating different hindlimb muscles, as well as between forelimb and hindlimb peripheral nerves. In contrast, axonal transport is faster in MNs compared to sensory neurons innervating the same muscle. Found periodically across the myelin sheath, Nodes of Ranvier (NoR) are short uncovered axonal domains that facilitate action potential propagation. Currently, it remains unresolved how the distinct molecular structures of the NoR impact axonal transport dynamics. Here, using intravital time-lapse microscopy of sciatic nerves in live, anaesthetised mice, we assessed diverse organelle dynamics at the NoR. We first observed that axonal morphologies were similar between fast and slow MNs, and found that signalling endosomes and mitochondria accumulate on the distal side of the NoR in both motor neuron subtypes. Assessment of axonal transport of signalling endosomes and mitochondria revealed a decrease in velocity and increase in pausing as the organelles transit through the NoR, followed by an increase in speed in the adjacent intranodal region. Collectively, this study has established axonal transport dynamics of two independent organelles at the NoR in vivo, and has relevance for several pathologies affecting peripheral nerves and the NoR, such as peripheral neuropathy, motor neuron diseases, and/or multiple sclerosis.

neuroscience↗

bioRxiv2022

Bimodal regulation of axonal transport by the GDNF-RET signalling axis in healthy and diseased motor neurons

Deficits in axonal transport are one of the earliest pathological outcomes in several models of amyotrophic lateral sclerosis (ALS), including SOD1G93A mice. Evidence suggests that rescuing these deficits prevents disease progression, stops denervation, and extends survival. Kinase inhibitors have been previously identified as transport enhancers, and are being investigated as potential therapies for ALS. For example, inhibitors of p38 mitogen-activated protein kinase and insulin growth factor receptor 1 have been shown to rescue axonal transport deficits in vivo in symptomatic SOD1G93A mice. In this work, we investigated the impact of RET, the tyrosine kinase receptor for glial cell-line-derived neurotrophic factor (GDNF), as a modifier of axonal transport. We identified fundamental interplay between RET signalling and axonal transport in both wild type and SOD1G93A motor neurons in vitro. We demonstrated that blockade of RET signalling using pharmacological inhibitors and genetic knockdown enhances signalling endosome transport in wild type motor neurons and uncovered a divergence in the response of primary motor neurons to GDNF compared with cell lines. Finally, we demonstrated that inhibition of the GDNF-RET signalling axis rescues in vivo transport deficits in early symptomatic SOD1G93A mice, promoting RET as a potential therapeutic target in the treatment of ALS.

neuroscience↗

bioRxiv2021

BDNF-dependent modulation of axonal transport is selectively impaired in ALS

Axonal transport ensures long-range delivery of essential cargoes between proximal and distal compartments of neurons, and is needed for neuronal development, function, and survival. Deficits in axonal transport have been detected at pre-symptomatic stages in mouse models of amyotrophic lateral sclerosis (ALS), suggesting that impairments are fundamental for disease pathogenesis. However, the precise mechanisms responsible for the transport deficits and whether they preferentially affect -motor neuron (MN) subtypes remain unresolved. Here, we report that stimulation of wild-type neurons with brain-derived neurotrophic factor (BDNF) enhances trafficking of signalling endosomes specifically in fast MNs (FMNs). In early symptomatic SOD1G93A mice, FMNs display selective impairment of axonal transport and develop an insensitivity to BDNF stimulation, with pathology upregulating classical non-pro-survival receptors in muscles and sciatic nerves. Altogether, these data indicate that cell- and non-cell autonomous BDNF signalling is impaired in vulnerable SOD1G93A MNs, thus identifying a new key deficit in ALS amenable for future therapeutic interventions.

neuroscience↗

bioRxiv2018

ALS mice carrying pathological mutant TDP-43, but not mutant FUS, display axonal transport defects in vivo

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease resulting from a complex interplay between genetics and environment. Impairments in the basic neuronal process of axonal transport have been identified in several ALS models. However, in vivo evidence of early/pre-symptomatic deficiencies in neuronal cargo trafficking remains limited, thus the pathogenic importance of axonal transport to the ALS disease spectrum remains to be fully resolved. We therefore analysed the in vivo dynamics of retrogradely transported, neurotrophin-containing signalling endosomes in motor neuron axons of two new mouse models of ALS that have mutations in different RNA processing genes (Tardbp and Fus). TDP-43M337V mice, which show neuromuscular pathology but no overt motor neuron loss, displayed in vivo perturbations in axonal transport that manifested between 1.5 and 3 months and preceded motor symptom onset. In contrast, signalling endosome transport remained largely unaffected in mutant Fus{Delta}14/+ mice, despite 20% motor neuron loss. These findings indicate that deficiencies in retrograde neurotrophin signalling and axonal transport are not common to all ALS-linked genes, and that there are inherent and mechanistic distinctions in the pathogenesis of ALS caused by mutations in different RNA processing genes.

neuroscience↗