Biology subjects

Cadot, B.

Publications and source records attributed to Cadot, B..

10 recordsLinked to original sources

bioRxiv2026

GDF5 as a Multimodal Protector of the Motor Unit in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis is characterized by the progressive dismantling of the motor unit. While "dying back" hypothesis suggests that peripheral neuromuscular dysfunction precedes motor neuron loss, the molecular mechanisms limiting endogenous compensatory responses remain poorly understood. We longitudinally examined neuromuscular decline and GDF5-SMAD1/5/8 signaling in SOD1G93A mice. Our findings revealed a translational checkpoint linked to the lncRNA Myoparr that suppresses GDF5 production at symptom onset. To overcome this deficit, we delivered AAV9-GDF5 at the symptomatic stage. GDF5 supplementation restored SMAD signaling balance, shifting the motor unit from a pro-atrophic TGF-{beta}-SMAD2/3 toward a pro-myogenic SMAD1/5 profile. Treatment preserved muscle mass, reduced mitochondrial reactive oxygen species, and maintained neuromuscular junction integrity, including peri-synaptic glial support. GDF5 also promoted molecular recovery of spinal MNs by enhancing homeostatic marker expression. Together, these findings identify GDF5 as a multimodal stabilizer of the motor unit and highlight its potential as therapeutic target in combinatorial strategies aimed at coupling motor unit stabilization with central neuroprotective interventions.

physiology↗

bioRxiv2025

GDF5 modulation of MuSC pool as a potential therapeutic benefit for DMD

Duchenne muscular dystrophy (DMD) is a fatal disease caused by dystrophin deficiency, leading to degeneration of the entire musculature. To improve muscle pathophysiology and gene therapy for DMD, we investigated the potential of growth differentiation factor 5 (GDF5) in the DMD mdx mouse model. We showed that the overexpression of GDF5 in the muscle improved its histology, reduced inflammation, modulated regeneration and induced the appearance of de novo fibers. We demonstrated that muscle satellite cells (MuSCs) are targeted by GDF5 which enhanced their proliferation and slowed down their myogenic commitment and finally their fusion. When combined with AAV-mediated microdystrophin gene therapy, the leading therapeutic strategy, GDF5 further increased the number of microdystrophin-positive fibers compared to gene therapy alone. These findings highlight GDF5 as a promising modulator of DMD pathology and provide the first evidence of a synergistic effect of the combination of GDF5-based intervention and AAV-microdystrophin treatment.

cell biology↗

bioRxiv2025

Generation and Characterization of Col6a1 knock-in mice: A Promising Pre-Clinical Model for Collagen VI-Related Dystrophies

Collagen VI Related Dystrophies (COL6-RD) are congenital muscle diseases, typically inherited as an autosomal dominant trait. A frequent type of mutation involves glycine substitutions in the triple helical domain of collagen VI alpha chains, exerting a dominant-negative effect on the unaltered protein. Despite this, no prior animal model captured this mutation type. Using CRISPR/Cas9, we generated transgenic mice with the equivalent of the human COL6A1 c.877 G>A; p. Gly293Arg mutation. We characterized their skeletal muscle phenotype over time, utilizing computer-aided tools applied to standardized parameters of muscle pathology and function. Knock-in mice exhibited early-onset reduced muscle weight, myopathic histology, increased fibrosis, reduced collagen VI expression, muscle weakness, and impaired respiratory function. These features provide adequate outcome measures to assess therapeutic interventions. The different automated image analysis methods deployed here analyze thousands of features simultaneously, enhancing accuracy in describing muscle disease models. Overall, the Col6a1 Ki Gly292Arg mouse model offers a robust platform to deepen our understanding of COL6-RD and advance its therapeutic landscape. Summary StatementWe generated and characterized over time the first mouse model representing dominant negative glycine substitutions in the alpha chains of collagen VI that are a frequent cause of Collagen VI-Related Dystrophies.

neuroscience↗

bioRxiv2024

Early endosome disturbance and endolysosomal pathway dysfunction in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a lethal dystrophy characterized by the progressive loss of muscle fibers caused by mutations in DMD gene and absence of the dystrophin protein. While autophagy and lysosome biogenesis defects have been described in DMD muscles, the endosomal pathway has never been studied. Here, we showed that impaired lysosome formation is associated with altered acidification and reduced degradative function of the endolysosomal pathway in muscle cells derived from DMD patients. Our data demonstrated that early endosomes are increased in these cells as well as in muscle biopsies from DMD patients and two animal models of DMD, mdx mice and GRMD dogs. We determined that these abnormalities are due to the lack of dystrophin per se and could be correlated with disease progression and severity. We further identified an abnormal upregulation of the Rab5 GTPase protein, one key actor of early endosomal biogenesis and fusion, in the three DMD models which may underlie the endosomal defects. Finally, we demonstrated that Rab5 knock-down in human DMD muscle cells as well as dystrophin restoration in GRMD dogs, normalize Rab5 expression levels and rescue endosomal abnormalities. This study unveils a defect in a pathway essential for muscle homeostasis and for efficacy of adeno associated virus vectors and antisense oligonucleotides-mediated therapies.

pathology↗

bioRxiv2022

Caveolae and Bin1 form ring-shaped platforms for T-tubule initiation

Excitation-contraction coupling requires a highly specialized membrane structure, the triad, composed of a plasma membrane invagination, the T-tubule, surrounded by two sarcoplasmic reticulum terminal cisternae. Although the precise mechanisms governing T-tubule biogenesis and triad formation remain largely unknown, studies have shown that caveolae participate in T-tubule formation and mutations of several of their constituents induce muscle weakness and myopathies. Here, we demonstrate that, at the plasma membrane, caveolae composed of caveolin-3 and Bin1 assemble into ring-like structures from which emerge tubes enriched in the dihydropyridine receptor. Overexpression of Bin1 lead to the formation of both rings and tubes and we show that Bin1 forms scaffolds on which caveolae accumulate to form the initial T-tubule. Cav3 deficiency caused by either gene silencing or pathogenic mutations cause defective ring formation and perturbed Bin1-mediated tubulation that may explain defective T-tubule organization in mature muscles. Our results uncover new pathophysiological mechanisms that may prove relevant to myopathies caused by Cav3 or Bin1.

cell biology↗

bioRxiv2022

IMPatienT: an integrated web application to digitize, process and explore multimodal patient data.

Medical acts, such as imaging, lead to the production of several medical text report that describes the relevant findings. This induces multimodality in patient data by linking image data to free-text and consequently, multimodal data have become central to drive research and improve diagnosis. However, the exploitation of patient data is challenging as the ecosystem of analysis tools is fragmented depending on the type of data (images, text, genetics), the task (processing, exploration) and domains of interest (clinical phenotype, histology). To address the challenges, we present IMPatienT (Integrated digital Multimodal PATIENt daTa), a simple, flexible and open-source web application to digitize, process and explore multimodal patient data. IMPatienT has a modular architecture to: (i) create a standard vocabulary for a domain, (ii) digitize and process free-text data, (iii) annotate images and perform image segmentation, and (iv) generate a visualization dashboard and perform diagnosis suggestions. We showcased IMPatienT on a corpus of 40 simulated muscle biopsy reports of congenital myopathy patients. As IMPatienT relies on a user-designed vocabulary, it can be adapted to any domain of research and can be used as a patient registry for exploratory data analysis (EDA). A demo instance of the application is available at https://impatient.lbgi.fr/.

bioinformatics↗

bioRxiv2020

Ctdnep1 and Eps8L2 regulate dorsal actin cables for nuclear positioning during cell migration

Cells actively position their nuclei within the cytoplasm for multiple cellular and physiological functions. Different cell types position their nuclei away from the leading edge to migrate properly. In migrating fibroblasts, nuclear positioning is driven by dorsal actin cables connected to the nuclear envelope by the LINC complex on Transmembrane Actin-associated Nuclear (TAN) lines. How dorsal actin cables are organized to form TAN lines is unknown. Here, we report a role for Ctdnep1/Dullard, a nuclear envelope phosphatase, and the actin regulator Eps8L2, on nuclear positioning. We demonstrate that Ctdnep1 and Eps8L2 directly interact to regulate the formation and thickness of dorsal actin cables required for TAN lines engagement for nuclear positioning. Our work establishes a novel mechanism to locally regulate actin at the nuclear envelope for nuclear positioning.

cell biology↗

bioRxiv2019

LINC complexes are mechanotransducers that discriminate Epithelial-Mesenchymal Transition programs

LINC complexes are transmembrane protein assemblies that physically connect the nucleo- and cytoskeletons through the nuclear envelope. Dysfunctions of LINC complexes are associated with pathologies such as cancer and muscular disorders. The mechanical roles of LINC complexes in these contexts are poorly understood. To address this, we used genetically encoded FRET biosensors of molecular tension in LINC complex proteins of fibroblastic and epithelial cells in culture. We exposed cells to mechanical, genetic and pharmacological perturbations, mimicking a range of physiological and pathological situations. We show that LINC complex proteins experience tension generated by the cytoskeleton and act as mechanical sensors of cell packing. Moreover, the LINC complex discriminates between inductions of partial and complete epithelial-mesenchymal transitions (EMT). We identify the implicated mechanisms, which associate nesprin tension sensing with -catenin capture at the nuclear envelope, thereby regulating {beta}-catenin transcription. Our data thus implicate that LINC complexes are mechanotransducers that fine-tune {beta}-catenin signaling in a manner dependent on the Epithelial-Mesenchymal Transition program.

cell biology↗

bioRxiv2019

Actin accumulates nesprin-2 at the front of the nucleus during confined cell migration

The mechanisms by which cells exert forces on their nuclei to migrate through openings smaller than the nuclear diameter remain unclear. In microfluidic devices, the hourglass shape of the nucleus and its strain patterns as it translocates through narrow constrictions suggest pulling forces. We use CRISPR/Cas9 to fluorescently label nesprin-2 giant, a protein that links the cytoskeleton to the interior of the nucleus. We demonstrate that nesprin-2 giant accumulates at the front of the nucleus during nuclear deformation through narrow constrictions, independently of the nuclear lamina. We find that nesprins are more mobile than lamin A/C, at time scales similar to that of the accumulation. Using artificial constructs, we show that the actin-binding domain of nesprin-2 is necessary and sufficient to generate this accumulation, and that microtubules are not necessary. Actin filaments are organized in a barrel structure around the moving nucleus in the direction of movement, suggesting that this structure is responsible for redistribution of nesprins towards the front of the nucleus. Two-photon ablation and the use of drugs inhibiting the cytoskeleton demonstrate a pulling force on the nucleus from the front of the cell that is dependent on formin and actomyosin contractility. This elastic recoil is significantly reduced when nesprins are reduced at the nuclear envelope. We thus show that actin redistributes nesprin-2 giant towards the front of the nucleus and contributes to pulling the nucleus through narrow constrictions, in concert with myosin.

cell biology↗

bioRxiv2019

Over-activation of BMP signaling in neural crest cells precipitates heart outflow tract septation

Establishment of separated pulmonary and systemic circulations in vertebrates relies on the key role of neural crest cells (NCC) for the septation of the embryonic cardiac outflow tract (OFT). Absence of NCCs induces OFT septation defects, analogous to a loss of Bone Morphogenetic Proteins (BMPs) activity, though it remains unclear how BMPs control cardiac NCC differentiation and behaviour. To address this question, we monitored cardiac NCC state upon gain in BMP signaling, caused by the deletion of Dullard, using 3D-imaging and single cell transcriptomics. Specific loss of Dullard in the NCC results in premature OFT septation, pulmonary artery obstruction and embryonic death. This is caused by uncontrolled NCC convergence towards the endocardium and asymmetrical myocardial differentiation, promoted by elevated levels of the guiding cue Sema3c and decreased levels in mesenchymal trait markers. Furthermore, we unraveled the molecular basis of the zipper-like OFT septation where graded Sema3c expression follow a gradient of BMP activation in NCC along the OFT length.

developmental biology↗