Biology subjects

Villarroel-Campos, D.

Publications and source records attributed to Villarroel-Campos, D..

4 recordsLinked to original sources

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↗

bioRxiv2023

BDNF controls phosphorylation and transcriptional networks governing cytoskeleton organization and axonal regeneration

The cell-intrinsic capacity of neurons to regenerate axons requires widespread coordination of the transcriptome, activation of multiple kinases, and reorganization of the cytoskeleton. Axonal repair is also influenced by extrinsic activating factors, such as neurotrophins. Here, we reveal that brain-derived neurotrophic factor (BDNF) amplifies multiple neuron-intrinsic programs to foster axonal regeneration in human motor neurons. Through metabolic RNA sequencing and phosphoproteomic profiling, we elucidate BDNF signalling and its role in axonal regeneration. We discover that BDNF controls RNA stability and transcriptional programs that converge with regeneration-associated gene (RAG) sets. We further unveil that BDNF governs the phosphorylation of multiple proteins essential for cytoskeletal dynamics, a major determinant of effective nerve regeneration. Using compartmentalized neuronal cultures, we demonstrate that the regeneration driven by BDNF depends on the axon-specific activation of ERK/RSK/S6K kinase pathway. We propose a model in which BDNF augments neuron-intrinsic pathways to drive axonal regeneration in human motor neurons. TeaserBDNF aids nerve repair by fine-tuning the metabolism of RNA and by changing the building blocks of the nerve cell cytoskeleton.

molecular biology↗

bioRxiv2023

Boosting BDNF in muscle rescues impaired in vivo axonal transport in a mouse model of DI-CMTC peripheral neuropathy

Charcot-Marie-Tooth disease (CMT) is a genetic peripheral neuropathy caused by mutations in many functionally diverse genes. The aminoacyl-tRNA synthetase (ARS) enzymes, which transfer amino acids to partner tRNAs for protein synthesis, represent the largest protein family genetically linked to CMT aetiology, suggesting pathomechanistic commonalities. Dominant intermediate CMT type C (DI-CMTC) is caused by YARS1 mutations driving a toxic gain-of-function in the encoded tyrosyl-tRNA synthetase (TyrRS), which is mediated by exposure of consensus neomorphic surfaces through conformational changes of the mutant protein. In this study, we first showed that human DI-CMTC-causing TyrRSE196K mis-interacts with the extracellular domain of the BDNF receptor TrkB, an aberrant association we have previously characterised for several mutant glycyl-tRNA synthetases linked to CMT type 2D (CMT2D). We then performed temporal neuromuscular assessments of YarsE196K mice modelling DI-CMT. We determined that YarsE196K homozygotes display a selective, age-dependent impairment in in vivo axonal transport of neurotrophin-containing signalling endosomes, phenocopying CMT2D mice. This impairment is replicated by injection of recombinant TyrRSE196K, but not TyrRSWT, into muscles of wild-type mice. Augmenting BDNF in DI-CMTC muscles, through injection of recombinant protein or muscle-specific gene therapy, resulted in complete axonal transport correction. Therefore, this work identifies a non-cell autonomous pathomechanism common to ARS-related neuropathies, and highlights the potential of boosting BDNF levels in muscles as a therapeutic strategy.

neuroscience↗

bioRxiv2023

The tyrosine phosphatase LAR acts as a receptor of the nidogen-tetanus toxin complex

Tetanus toxin is one of the most potent neurotoxins and is the causative agent of tetanus. This neurotoxin binds to the neuromuscular junction and, after internalisation into motor neurons, undergoes long-distance axonal transport and transcytosis into spinal cord inhibitory interneurons. Inside the cytoplasm of interneurons, the catalytic chain of the toxin blocks neurotransmitter release, leading to spastic paralysis. Whilst the effects of tetanus toxin intoxication have been extensively studied, the molecular composition of its receptor complex is still poorly understood. We have previously shown that the extracellular matrix proteins nidogens are essential for binding of the toxin to the neuromuscular junction. In this study, we show that the tyrosine phosphatase LAR interacts with the nidogen-tetanus toxin complex and enables its uptake into motor neurons. Binding of LAR to the toxin complex is mediated by its fibronectin III domains, which we have harnessed to inhibit tetanus toxin entry into motor neurons. Surprisingly, this function of LAR is independent of its role in regulating the neurotrophic activity of the TrkB receptor, which has previously been shown to augment the axonal transport of signalling endosomes containing tetanus neurotoxin. These findings identify a multi-subunit complex acting as a protein receptor for tetanus neurotoxin, and demonstrate a novel endocytic trafficking route for extracellular matrix proteins in neurons. Our study paves the way for dissecting the molecular mechanisms that control the recognition and uptake of physiological ligands and pathological proteins at the neuronal plasma membrane, as well as their targeting to the axonal retrograde pathway for long-distance transport within the nervous system.

cell biology↗