Biology subjects

Marcelle, C.

Publications and source records attributed to Marcelle, C..

9 recordsLinked to original sources

bioRxiv2026

A Cre-responsive reporter quail for flexible genetic lineage tracing

Genetic lineage tracing is a powerful approach for investigating cell fate and tissue development, but versatile Cre/loxP-based tools remain limited in avian models. Here, we generated and characterised a Cre-responsive transgenic quail line that enables permanent genetic labelling of embryonic cell populations. The reporter line ubiquitously expresses nuclear-localised mCherry, which is excised following Cre-mediated recombination, enabling expression of nuclear-localised EGFP. We demonstrate that this reporter can be coupled to multiple Cre delivery strategies, providing flexible spatial and temporal control of lineage labelling. Ubiquitous or cell-type-specific Cre expression induces recombination and stable EGFP labelling that is maintained during clonal expansion. Optogenetic activation of a split Cre system enables highly spatially and temporally restricted recombination. Furthermore, lipid nanoparticle-mediated delivery of Cre mRNA enables efficient recombination in distinct embryonic cell populations, including mesodermal, neuroepithelial, neural crest, endothelial and circulating cells. This transgenic reporter quail provides a flexible platform for permanent lineage labelling without the need to generate tissue-specific Cre transgenic lines and can be readily combined with diverse Cre delivery strategies to investigate cell fate, lineage and morphogenesis in vivo.

developmental biology↗

bioRxiv2026

Curvature-guided chiral collective organization of myoblast tissues

Surface curvature is a fundamental geometric cue in tissue morphogenesis, yet its role in guiding collective cell organization has remained elusive. Here, we show that curvature acts as a geometric control parameter that shapes supracellular alignment and chirality while modulating myogenic differentiation in myoblast tissues. Cells cultured on curved substrates self-organize into robust helical assemblies whose handedness is set, and can be reversed, by the sign of curvature: convex fibers produce right-handed helices, whereas concave channels invert the chirality. We identify a previously hidden clockwise bias in single-cell motion associated with the helical actin cytoskeleton. A minimal continuum theory coupling an effective chiral drive to curvature quantitatively captures the emergence and reversal of tissue-scale chiral alignment. On substrates with spatially varying curvature, local curvature gradients organize patterned multicellular architectures while preserving a global handedness. Curvature is also associated with myogenic state, with higher curvature linked to reduced or delayed differentiation. Together, these findings reveal how complex geometries shape the alignment, symmetry, and cellular state of living tissues.

biophysics↗

bioRxiv2024

Mechanical stresses govern myoblast fusion and myotube growth

Myoblast fusion into multinucleated myotubes is essential for skeletal muscle development and repair, yet how tissue-scale mechanics contributes to this process remains poorly understood. Here, we show that primary myoblasts behave as an evolving active nematic system in which actomyosin-dependent stresses, extracellular-matrix (ECM) remodeling and fusion-driven myotube growth are dynamically coupled. As myoblasts fuse into elongated myotubes, orientational order increases and the nematic field is progressively reshaped. We identify a strong coupling between cellular and ECM nematic organization, whereby cytoskeleton-dependent ECM remodeling stabilizes topological defects and reinforces their associated stress patterns. Fusion events preferentially accumulate near comet-shaped +1/2 defects, which correspond to regions of high compressive stress predicted by our theoretical model. Our findings support a model in which the intrinsic fusion machinery provides fusion competence, while ECM-stabilized nematic stress patterns spatially bias the localization of fusion events. Fusion-driven myotube growth then feeds back on the mechanical landscape, increasing nematogen length and stress magnitude. Together, these results reveal a self-reinforcing biomechanical mechanism that contributes to the organization of myoblast fusion and myotube growth, with potential relevance for developmental and regenerative morphogenesis.

biophysics↗

bioRxiv2024

Early lineage segregation of primary myotubes from secondary myotubes and adult muscle stem cells.

Myogenesis in amniotes unfolds through two consecutive waves. The primary myotube lineage is characterized by the expression of slow myosin, sometimes in combination with fast myosin, and may serve as a scaffold for the secondary lineage, which expresses exclusively fast myosin. The embryonic origin of these two lineages, their relationship, and their connection to adult muscle stem cells are unknown. Here, we employed innovative strategies, combining novel TCF-LEF/{beta}-catenin signaling reporters with the precise spatiotemporal control of in vivo electroporation in avian embryos, to track limb muscle progenitors from early migration to late fetal stages. Strikingly, we uncovered two distinct progenitor populations co-existing from the earliest stages of limb myogenesis, with specific developmental fates: reporter-positive progenitors exclusively form primary myotubes, while reporter-negative progenitors generate secondary myotubes and adult muscle stem cells. Furthermore, we uncovered a novel function of TCF-LEF/{beta}-catenin signaling in regulating the spatial organization of the primary myotube lineage via CXCR4-mediated control of myoblast migration, likely contributing to its proposed organizing function. By redefining the embryonic origins of these myogenic populations, our findings not only resolve a longstanding question in muscle biology but also provide a crucial molecular entry point for understanding the cellular and molecular underpinnings of muscle fiber type diversity and function.

developmental biology↗

bioRxiv2021

TopFlash transgenic quail reveals dynamic TCF/beta-catenin signaling during avian embryonic development

The Wnt/{beta}-catenin signaling pathway is highly conserved throughout evolution and it plays crucial roles in several developmental and pathological processes. Wnt ligands can act at a considerable distance from their sources and it is therefore necessary to examine not only the Wnt-producing but also the Wnt-receiving cells and tissues to fully appreciate the many functions of this pathway. To monitor Wnt activity, multiple tools have been designed which consist of multimerized Wnt signaling response elements (TCF/LEF binding sites) driving the expression of fluorescent reporter proteins (e.g. GFP, RFP) or of LacZ. The high stability of those reporters leads to a considerable accumulation in cells activating the pathway, thereby making them easily detectable. However, this makes them unsuitable to follow temporal changes of the pathways activity during dynamic biological events. Even though fluorescent transcriptional reporters can be destabilized to shorten their half-lives, this dramatically reduces signal intensities, particularly when applied in vivo. To alleviate these issues, we developed two transgenic quail lines in which high copy number (12x or 16x) of the TCF/LEF binding sites drive the expression of destabilized GFP variants. Translational enhancer sequences derived from viral mRNAs were used to increase signal intensity and specificity. This resulted in transgenic lines efficient for the characterisation of TCF/{beta}-catenin transcriptional dynamic activities during embryogenesis, including using in vivo imaging. Our analyses demonstrate the use of this transcriptional reporter to unveil novel aspects of Wnt signaling, thus opening new routes of investigation into the role of this pathway during amniote embryonic development.

developmental biology↗

bioRxiv2020

Macrophages provide a transient muscle stem cell niche via NAMPT secretion

Skeletal muscle is paradigmatic of a regenerative tissue that repairs itself via the activation of a resident stem cell1. Termed the satellite cell, these normally quiescent cells are induced to proliferate by ill-defined wound-derived signals2. Identifying the source and nature of these pro-regenerative cues has been hampered by an inability to visualise the complex cellular interactions that occur within the wound environment. We therefore developed a zebrafish muscle injury model to systematically capture satellite cell interactions within the injury site, in real time, throughout the repair process. This analysis identified that a specific subset of macrophages dwells within the injury, establishing a transient but obligate stem cell niche required for stem cell proliferation. Single cell profiling identified specific signals secreted from dwelling macrophages that include the cytokine, Nicotinamide phosphoribosyltransferase (NAMPT/Visfatin/PBEF). Here we show that NAMPT secretion from the macrophage niche is required for muscle regeneration, acting through the C-C motif chemokine receptor type 5 (CCR5) expressed on muscle stem cells. This analysis reveals that along with their well-described ability to modulate the pro-inflammatory and anti-inflammatory phases of wound repair, specific macrophage populations also provide a transient stem cell-activating niche, directly supplying pro-proliferative cues that govern the timing and rate of muscle stem cell-mediated repair processes.

cell biology↗

bioRxiv2019

Generation of transgenic quails by in vivo transfection of primordial germ cells

During development, dynamic changes in tissue shapes known as morphogenesis result from the exquisite orchestration of signalling pathways, cell-cell interactions, cell divisions, and coordinated movements. How cells within embryos adopt a vast array of cell fates and tissue shapes in such an ever-changing environment has fascinated scientists for generations, yet the ability to observe and characterize those rapid changes has proven technically challenging in higher vertebrates. The japanese quail (Coturnix coturnix japonica) is an attractive model where basic rules driving morphogenesis in amniotes can be deciphered using genetic approaches. Similar to the more popular chicken model, the quail embryo is easily accessible to a wide range of manipulations and live imaging. A decisive asset of quail over chicken is a much shorter life cycle, which makes its use as genetic model for basic research extremely appealing. To date, all existing transgenic quail lines were generated using replication-deficient lentiviruses, but diverse limitations of this approach have hindered the widespread expansion of such technology. Here, we successfully used a plasmid-based in vivo transfection of quail primordial germ cells (PGCs) to generate a number of transgenic quail lines over a short period of time. The plasmid-based approach is simple, efficient and it allows using the infinite variety of genome engineering approaches developed in other models, such as strategies to facilitate transgenic bird selection, shown here. This major technological development completes the vast panel of techniques applicable to the avian model, making it one of the most versatile experimental systems available.

developmental biology↗

bioRxiv2019

Auto-inhibition of myoblast fusion by cyclic receptor signalling.

Fusion of nascent myoblasts to pre-existing myofibres is critical for skeletal muscle growth and repair. The vast majority of molecules known to regulate myoblast fusion are necessary in this process. Here we uncover, through high-throughput in vitro assays and in vivo studies in the chicken embryo, that TGF{beta} (SMAD2/3-dependent) signalling acts as a molecular brake on muscle fusion. While constitutive activation of the pathway arrests fusion, its inhibition leads to a striking over-fusion phenotype. This dynamic control of TGF{beta} signalling in the embryonic muscle relies on a unique receptor complementation mechanism, prompted by the merging of myoblasts with myofibres, each carrying one component of the heterodimer receptor complex. The competence of myofibres to fuse is restored through endocytic degradation of activated receptors. Altogether, this study shows that muscle fusion is a self-regulated process that relies on cyclic TGF{beta} signalling to regulate its pace.

developmental biology↗

bioRxiv2018

AKT, NOTCH and GSK3β interact to trigger early myogenesis in vertebrate embryos.

During early embryonic development, migrating neural crest cells expressing the NOTCH ligand Delta1 (DLL1) trigger the activation of NOTCH1 signaling in selected epithelial cells within newly formed somites. A key event in this process is a dramatic inhibition of GSK3{beta} activity, initiated by the activation of NOTCH1 and that takes place independent of its transcriptional function. Here, we investigated the mechanism whereby NOTCH1 exerts its non-canonical function in somites. Using the activation of myogenesis as a read-out of the ability of NOTCH receptors to trigger transcription-independent responses in somites, we found that all NOTCH receptors (1-4) activate MYF5 expression and we showed that the RAM (RBPJ-Associated Molecule) domain of the NOTCH Intracellular Domain (NICD) is necessary and sufficient in this process. We then demonstrated that the NOTCH1 Intracellular Domain (NICD1) physically interacts in the cytosol with GSK3{beta} and with the serine threonine protein kinase AKT. Activating AKT triggers myogenesis, likely via the inhibition of GSK3{beta}. We found that AKT, in a dose-dependent manner, decreases the transcriptional activity of NOTCH, suggesting a role in the balance between the canonical and non-canonical functions of NOTCH. Altogether these data strongly support the hypothesis that transcription-independent function of NICD is a central mechanism driving myogenesis in early somites and suggests that, in this tissue, AKT, NOTCH and GSK3{beta} interact in the cytoplasm to trigger a signaling cascade that leads to the formation of the early myotome in vertebrates.

developmental biology↗