Biology subjects

Juban, G.

Publications and source records attributed to Juban, G..

9 recordsLinked to original sources

bioRxiv2026

NEUROMUSCULAR ELECTRICAL STIMULATION LIMITS MUSCLE WEAKNESS, ATROPHY, MODULATES SATELLITE CELL FUNCTION AND REDUCES INFLAMMATION IN CANCER CACHEXIA

BackgroundCancer cachexia (CC) is characterized by skeletal muscle atrophy and reduced strength, partly linked to dysfunction of muscle stem cells (MuSCs) and alterations in their niche. Although exercise may mitigate muscle loss, its effects in CC remain debated and its feasibility is often limited in advanced patients. Neuromuscular electrical stimulation (NMES) offers a promising alternative, by promoting MuSC proliferation and fusion, increasing muscle size and macrophage content in healthy muscle. This study investigated whether NMES, initiated at tumor onset, could improve MuSC regulation and its niche while limiting muscle atrophy and weakness in a tumor-bearing mouse model. MethodsTen-week-old male BALB/c mice were subcutaneously injected with C26 tumor cells or PBS. Tumor-bearing mice were divided into NMES-treated (C26 NMES) and non-stimulated controls (C26). NMES consisted of six sessions (two series of three consecutive daily sessions separated by one rest day), starting seven days post-inoculation when tumors became visible. Each session was delivered at a submaximal intensity corresponding to 15% of maximal strength. Muscle mass, myofiber size, strength and cellular composition were assessed. ResultsMuscle mass was decreased by 13% in C26 mice as compared to PBS controls, while C26 NMES mice showed a [~]7% improvement over C26 mice. Mean myofiber size decreased similarly in both tumor-bearing groups as compared to PBS controls (-12-14%). However, NMES reduced the proportion of small myofibers (400-600 {micro}m{superscript 2}) as compared to C26 mice. Maximal torque loss was less severe in C26 NMES mice (-28%) than in C26 mice (-34%). As compared with PBS mice, C26 mice exhibited increased MuSC proliferation (+97%) but reduced differentiation (-61%), as indicated by fewer myogenin-positive cells. NMES normalized MuSC proliferation, restored myogenin-positive cell number, and enhanced MuSC fusion, reflected by an increased number of PCM1-positive myonuclei (+8-11%). NMES also modulated inflammation, reducing neutrophils (-42%) and increasing macrophages (+35%), through the proliferation of CD169-positive resident macrophages (+106%). In vitro, macrophages exposed to C26 muscle extracts showed elevated pro-inflammatory markers (COX2 and TNF-; +21% and +16%) as compared to PBS controls. This effect was abolished with extracts from C26 NMES muscles. Additionally, C26 extracts reduced the expression of anti-inflammatory markers by macrophages (CD206 and IL-10; -23%), whereas NMES restored their levels to those of controls. ConclusionNMES-induced mild contractile activity is an effective stimulus for preserving muscle strength and mass, improving MuSC regulation, and modulating muscle inflammation in a mouse model of CC.

cell biology↗

bioRxiv2024

Macrophage-derived RNAseT2 stimulates muscle stem cell fusion via SLK/N-WASP/actin bundling

Muscle stem cells (MuSCs) fuse to form myofibers to repair skeletal muscle after injury. Within the regenerative MuSC niche, restorative macrophages stimulate MuSC fusion, although the molecular mechanisms involved are largely unknown. Here, we show that restorative macrophages secrete ribonuclease T2 (RNAseT2) to stimulate MuSC fusion. RNAseT2 entered MuSCs via the mannose receptor and induced the formation of actin bundles in MuSCs, enabling cell/cell fusion. Mechanistically, RNAseT2 bound to Ste20-like kinase (SLK), which itself triggered the phosphorylation-mediated activation of N-WASP, through Paxillin phosphorylation, allowing actin bundling necessary for MuSC fusion. In vivo, overexpressing RNAseT2 in regenerating muscle increased fusion in newly formed myofibers in mouse and zebrafish while macrophages deficient for RNAseT2 gene led to fusion defect and smaller myofibers. This study reveals a new function for the highly conserved RNAseT2 and provides a new molecular mechanism by which restorative macrophages support MuSC fusion during muscle repair.

cell biology↗

bioRxiv2024

Immune aging impairs muscle regeneration via macrophage-derived anti-oxidant selenoprotein P

Muscle regeneration is impaired in the aged organism, due to both intrinsic defects of muscle stem cells (MuSCs) and alterations of their environmental niche. However, the latter has still been poorly explored. Here, we compared and analyzed the time course of the various cell types constituting the MuSC niche during muscle generation in young and old mice. Aging altered the amplification of all niche cells with particularly prominent phenotypes in macrophages that impaired the resolution of inflammation in the old regenerating muscle. RNAsequencing of FACs-isolated MuSCs and non-myogenic niche cells during regeneration uncovered specific profiles and kinetics of genes and molecular pathways differentially regulated in old versus young regenerating muscle, indicating that each cell type responded to aging in a specific manner. Through this, we discovered that macrophages have a strong signature of aging with altered the activation of Selenoprotein P (Sepp1) expression in macrophages during the resolution of inflammation in regenerating muscle. Macrophage-specific deletion of Sepp1 gene was sufficient to impair the acquisition of the repair inflammatory profile, perturbed the support of macrophages to MuSCs in vitro and in vivo, and to cause inefficient skeletal muscle regeneration. When transplanted in aged mice, bone marrow from young WT mice, but not Sepp1 KOs, restored muscle regeneration to youthful levels. Altogether this work provides a unique resource to study the aging of the MuSC niche, reveals that aging of niche cells is asynchronous and establishes impaired macrophage dynamics/polarization and the anti-oxidant Selenoprotein P expression as drivers of age-related decline of muscle regeneration. Teaser: Cell profiling reveals asynchronicity of aging in the muscle stem cell niche and age-dependent macrophage/stem cell interactions through anti-oxidant selenoprotein P

physiology↗

bioRxiv2024

Polymeric nanoparticles delivery of AMPK activator 991 prevents its toxicity and improves muscle homeostasis in Duchenne Muscular Dystrophy

Muscular dystrophies, such as Duchenne muscular dystrophy (DMD), are caused by permanent muscle injuries leading to chronic inflammation. In that context, macrophages harbor an altered inflammatory profile that contributes to fibrosis through the secretion of the profibrotic cytokine TGF{beta}1. We previously showed that AMP-activated protein kinase (AMPK) activation reduces TGF{beta}1 secretion by macrophages and improves muscle homeostasis and muscle force in a mouse model of DMD. This makes AMPK an attractive therapeutic target for treating chronic inflammation and fibrosis in DMD. However, potent direct AMPK activators like compound 991 show strong adverse effects in vivo, preventing their direct use. Here, we encapsulated 991 into biodegradable polymeric poly(lactic-co-glycolic) acid (PLGA) nanoparticles for in vivo delivery, in an attempt to overcome toxicity issues. We show that 991-loaded PLGA nanoparticles retained drug activity on fibrotic macrophages in vitro, by reducing their secretion of TGF{beta}1. In the D2-mdx pre-clinical DMD mouse model, intravenously injected PLGA nanoparticles reached gastrocnemius and diaphragm muscles, which are the most affected muscles in this model. Chronic intravenous injections of 991-loaded PLGA nanoparticles decreased inflammation in both muscles, which was associated with fibrosis reduction and increase in myofiber size and muscle mass in the gastrocnemius. No impact on blood cell counts and liver enzymes was observed. These results demonstrate that nanomedicine is an efficient strategy to deliver AMPK activators in vivo to target inflammation and improve the dystrophic muscle phenotype.

pathology↗

bioRxiv2023

Alterations of the TGFb-sequestration complex member ADAMTSL1 levels are associated with muscular defects and rhabdomyosarcoma aggressiveness

Rhabdomyosarcoma (RMS) is the most frequent form of paediatric soft-tissue sarcoma and remains a medical challenge, holding in failure current therapeutic strategies. RMS shares histological features with cells of the muscle lineage and this cancer is thought to arise from malignant transformation of myogenic precursors. It has been proposed that RMS and myogenesis could represent the "Jekyll and Hyde" of skeletal muscle. The underlying idea is that some early steps of myogenic differentiation are blocked in RMS, and that understanding how the normal process has gone awry could help to decipher the biological underpinnings of tumorigenesis and tumor escape. It is widely agreed that extracellular matrix (ECM) interferes in skeletal muscle regeneration and that defects in ECM components are clinically significant. The challenge is now to decipher actors and mechanisms responsible for the transmission of signals to muscle cells and the subsequent alterations that could be associated with RMS. Using an original transgenic mice model, we show here that ADAMTSL1 is involved in skeletal muscle regeneration. As previously reported for other members of its family, ADAMTSL1 is part of the TGF-{beta}-ECM-sequestering complex and likely positively regulates TGF-{beta}-pathway activity. Last, we observed that ADAMTSL1 expression behaves as a strong prognostic factor in the aggressive fusion-positive RMS and correlates with a neural-like phenotype of tumor cells, resulting from gain of SMAD2/3/4 targets.

cancer biology↗

bioRxiv2020

Myofiber / pro-inflammatory macrophage interplay controls muscle damage in mdx mice

Duchenne Muscular Dystrophy is a genetic muscle disease characterized by chronic inflammation and fibrosis, which is mediated by a pro-fibrotic macrophage population expressing pro-inflammatory markers. The aim of this study was to characterize cellular events leading to the alteration of macrophage properties, and to modulate macrophage inflammatory status using the gaseous mediator H2S. We first analyzed the relationship between myofibers and macrophages in the mdx mouse model of Duchenne Muscular Dystrophy using coculture experiments. We showed that normal myofibers derived from mdx mice strongly skewed the polarization of resting macrophages towards a pro-inflammatory phenotype. Treatment of mdx mice with NaHS, an H2S donor, reduced the number of pro-inflammatory macrophages in skeletal muscle, which was associated with a decrease in the number of nuclei per fiber, a reduction of myofiber branching and a reduced fibrosis. These results identify an interplay between myofibers and macrophages where dystrophic myofibers contribute to the maintenance of a highly inflammatory environment that skews the macrophage status, which in turn favors myofiber damage, myofiber branching and fibrosis establishment. They also identify H2S donors as a potential therapeutic strategy to improve dystrophic muscle phenotype by modulating macrophage inflammatory status.

cell biology↗

bioRxiv2020

AMPKα1 is essential for Glucocorticoid Receptor triggered anti-inflammatory macrophage activation

SummaryMacrophages are key immune cells which mediate both the acute inflammatory phase and the repair phase after tissue damage. Macrophages switch from pro-inflammatory to anti-inflammatory cells that sustain repair and return to tissue homeostasis. We show that the metabolic sensor, AMP-activated protein kinase (AMPK) is essential for glucocorticoid induction of an anti-inflammatory macrophage phenotype. While canonical gene regulation by glucocorticoids was not affected by loss of AMPK, we identified AMPK-dependent glucocorticoid-regulated genes in macrophages, related to efferocytosis. AMPK-deficient macrophages do not acquire phenotypic and functional anti-inflammatory features upon glucocorticoid exposure. We identified FOXO3 as an AMPK-dependent regulator of glucocorticoid activity in macrophages. Loss of AMPK in macrophages in vivo abrogates glucocorticoid anti-inflammatory actions during post-injury muscle regeneration and endotoxin induced acute lung injury. These data highlight that the glucocorticoid receptor is dependent on AMPK for its immunomodulatory actions in macrophages, linking their metabolic status to transcriptional control in resolving inflammation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗

bioRxiv2019

Oncogenic Gata1 causes stage-specific megakaryocyte differentiation delay

The megakaryocyte/erythroid Transient Myeloproliferative Disorder (TMD) in newborns with Down Syndrome (DS) occurs when N-terminal truncating mutations of the hemopoietic transcription factor GATA1, that produce GATA1short protein (GATA1s), are acquired early in development. Prior work has shown that murine GATA1s, by itself, causes a transient yolk sac myeloproliferative disorder. However, it is unclear where in the hemopoietic cellular hierarchy GATA1s exerts its effects to produce this myeloproliferative state. Here, through a detailed examination of hemopoiesis from murine GATA1s ES cells and GATA1s embryos we define defects in erythroid and megakaryocytic differentiation that occur relatively in hemopoiesis. GATA1s causes an arrest late in erythroid differentiation in vivo, and even more profoundly in ES-cell derived cultures, with a marked reduction of Ter-119 cells and reduced erythroid gene expression. In megakaryopoiesis, GATA1s causes a differentiation delay at a specific stage, with accumulation of immature, kit-expressing CD41hi megakaryocytic cells. In this specific megakaryocytic compartment, there are increased numbers of GATA1s cells in S-phase of cell cycle and reduced number of apoptotic cells compared to GATA1 cells in the same cell compartment. There is also a delay in maturation of these immature GATA1s megakaryocytic lineage cells compared to GATA1 cells at the same stage of differentiation. Finally, even when GATA1s megakaryocytic cells mature, they mature aberrantly with altered megakaryocyte-specific gene expression and activity of the mature megakaryocyte enzyme, acetylcholinesterase. These studies pinpoint the hemopoietic compartment where GATA1s megakaryocyte myeloproliferation occurs, defining where molecular studies should now be focussed to understand the oncogenic action of GATA1s.\n\nScientific CategoryHaematopoiesis and Stem Cells\n\nKey PointsGATA1s-induced stage-specific differentiation delay increases immature megakaryocytes in vivo and in vitro, during development.\n\nDifferentiation delay is associated with increased numbers of cells in S-phase and reduced apoptosis.

cell biology↗

bioRxiv2018

Annexin A1 drives macrophage skewing towards a resolving phenotype to accelerate the regeneration of muscle injury through AMPK activation

Understanding the circuits that promote an efficient resolution of inflammation is crucial to deciphering the molecular and cellular processes required to promote tissue repair. Macrophages play a central role in the regulation of inflammation, resolution and repair/regeneration. Using a model of skeletal muscle injury and repair, herein we identify Annexin A1 (AnxA1) as the extracellular trigger of macrophage skewing towards a pro-reparative phenotype. Brought into the injured tissue initially by migrated neutrophils, and then over-expressed in infiltrating macrophages, AnxA1 activates FPR2/ALX receptors and the downstream AMPK signalling cascade leading to macrophage skewing, dampening of inflammation and regeneration of muscle fibres. Mice lacking AnxA1 in all cells or in myeloid cells only display a defect in this reparative process. In vitro experiments recapitulated these properties, with AMPK null macrophages lacking AnxA1-mediated polarization. Collectively, these data identify the AnxA1/FPR2/AMPK axis as a novel pathway in skeletal muscle injury regeneration.

cell biology↗