Biology subjects

Blavet, C.

Publications and source records attributed to Blavet, C..

5 recordsLinked to original sources

bioRxiv2024

Human adipose stromal cells differentiate towards a tendon phenotype with extracellular matrix production and adapted visco-elastic properties in a 3D-culture system

Tendon cell differentiation relies on molecular and mechanical parameters that control the expression of tendon-associated transcription factors and extracellular matrix proteins. However, the minimal cues able to initiate tendon differentiation from progenitor cells remains unknown. We analysed the tendon differentiation program in human adipose stromal cells (hASCs) cultured in a minimal 3D-system. We generated 3D-hASC constructs by embedding hASCs in a type-I collagen gel under a static uniaxial geometrical constraint with no additional molecular and mechanical cues, and assessed tendon-associated gene expression and mechanical properties for up to three weeks in culture. Analysis of tendon-associated genes revealed a molecular progression consistent with the acquisition of a tendon phenotype. The analysis of viscoelastic properties of 3D-hASC constructs by nano-indentation indicated a progressive increase in tissue stiffness up to 10 kPa, concomitant with a reduced stress relaxation indicative of solid-like mechanical properties. These changes in mechanical properties parallel the molecular change of matrix genes during the time of cultures. In summary, we have established that hASCs cultured in a minimal 3D-system progress into the tendon differentiation program associated with variations of mechanical properties.

developmental biology↗

bioRxiv2022

CXCR7 promotes foetal myoblast fusion at muscle fiber tips independently of Myomaker via a beta1integrin-EGFR-dependent mechanism

Muscle growth must be tightly regulated during development in order to obtain the final muscle shape. Myoblast fusion is a critical step of muscle growth, driving the formation of syncytial myofibers attaching at both ends to tendons. We investigated the role of the CXCR7 chemokine receptor in foetal muscle growth during chicken limb development. We show that CXCR7 displays a regionalized expression at the tips of myofibers close to tendons in foetal limb muscles, which is exclusive to the central location of the fusion gene MYOMAKER (TMEM8C in chicken) in foetal muscles. CXCR7 promotes myoblast fusion independently of TMEM8C in chicken limb muscles and in foetal myoblast cultures and requires EGF receptor signalling. The CXCR7 ligand, CXCL12, expressed in connective tissue, increases {beta}1integrin activation at the myotendinous junction and CXCR7 expression at muscle tips, resulting in a fusion promoting effect independent from a direct binding of CXCL12 to CXCR7 receptor. Our results evidence a CXCR7-dependent/TMEM8C-independent fusion mechanism at the myofiber tips that regulates muscle growth at the tendon/muscle interface during foetal myogenesis.

developmental biology↗

bioRxiv2020

BMP signalling directs a fibroblast-to-myoblast conversion at the connective tissue/muscle interface to pattern limb muscles

Positional information driving limb muscle patterning is contained in lateral plate mesoderm-derived tissues, such as tendon or muscle connective tissue but not in myogenic cells themselves. The long-standing consensus is that myogenic cells originate from the somitic mesoderm, while connective tissue fibroblasts originate from the lateral plate mesoderm. We challenged this model using cell and genetic lineage tracing experiments in birds and mice, respectively, and identified a subpopulation of myogenic cells at the muscle tips close to tendons originating from the lateral plate mesoderm and derived from connective tissue gene lineages. Analysis of single-cell RNA-sequencing data obtained from limb cells at successive developmental stages revealed a subpopulation of cells displaying a dual muscle and connective tissue signature, in addition to independent muscle and connective tissue populations. Active BMP signalling was detected in this junctional cell sub-population and at the tendon/muscle interface in developing limbs. BMP gain- and loss-of-function experiments performed in vivo and in vitro showed that this signalling pathway regulated a fibroblast-to-myoblast conversion. We propose that localised BMP signalling converts a subset of lateral plate mesoderm-derived fibroblasts to a myogenic fate and establishes a boundary of fibroblast-derived myonuclei at the muscle/tendon interface to control the muscle pattern during limb development.

developmental biology↗

bioRxiv2020

NOTCH inhibition promotes myoblast fusion by releasing HEYL repression on TMEM8C regulatory regions in foetal skeletal muscles

Differentiation and fusion are two intricate processes involved in skeletal muscle development. The close association of differentiation and fusion makes it difficult to address the process of fusion independently of differentiation. Using the fusion marker myomaker, named TMEM8C in chicken, we found that both TMEM8C transcripts and the differentiated and fusion-competent MYOG+ cells are preferentially regionalized in the central regions of limb foetal muscles in chicken embryos. Because the NOTCH signalling pathway is a potent inhibitor of muscle differentiation during developmental myogenesis, NOTCH function in myoblast fusion was not addressed so far. We analysed the consequences of NOTCH inhibition for myoblast fusion and TMEM8C expression during foetal myogenesis using in vitro and in vivo chicken systems. NOTCH inhibition following chicken embryo immobilisation or in myoblast cultures increased TMEM8C expression and myoblast fusion. Moreover, we showed that NOTCH inhibition induced the un-binding of the HEYL transcriptional repressor from the TMEM8C regulatory regions in limb muscles and myoblast cultures. These results identify a molecular mechanism underlying the fusion-promoting effect of NOTCH-inhibition during foetal myogenesis.

developmental biology↗

bioRxiv2018

In addition to being a marker for muscle connective tissue, Odd skipped-related 2 (OSR2) is expressed in differentiated muscle cells during chick development

The zinc finger transcription factor, Odd skipped-related 2 (OSR2) is a recognized marker of connective tissue in chick embryos. OSR2 gain- and loss-of-function experiments indicate a role in irregular connective tissue differentiation in chick limb undifferentiated cells. Re-investigation of OSR2 transcript location during chick development with in situ hybridization experiments showed that OSR2 was also expressed in differentiated muscle cells in limbs and head. OSR2 expression was also observed in differentiated myotubes in chick foetal myoblast cultures. This shows that in addition to being a marker of connective tissue, OSR2 is also expressed in muscle fibres during chick development.

developmental biology↗