Biology subjects

Chal, J.

Publications and source records attributed to Chal, J..

4 recordsLinked to original sources

bioRxiv2022

Transcriptomics, Regulatory Syntax, and Enhancer Identification in Heterogenous Populations of Mesoderm-Induced ESCs at Single-Cell Resolution

ESCs can adopt lineage-specific gene expression programs by stepwise exposure to defined factors, resulting in the generation of functional cell types. Bulk and single cell-based assays were employed to catalogue gene expression, histone modifications, chromatin conformation, and accessibility transitions in ESC populations and individual cells acquiring a presomitic mesoderm fate and undergoing further lineage specification. These assays identified cis-regulatory regions and transcription factors presiding gene expression programs occurring at defined ESC transitions and revealed the presence of heterogeneous cell populations within discrete ESC developmental stages. The datasets were employed to identify previously unappreciated genomic elements directing the initial activation of Pax7 and myogenic and neurogenic gene expression programs. This study provides a resource for the discovery of genomic and transcriptional features of pluripotent, mesoderm-induced ESCs, and ESCs-derived cell lineages.

developmental biology↗

bioRxiv2020

Prednisolone rescues Duchenne Muscular Dystrophy phenotypes in human pluripotent stem cells-derived skeletal muscle in vitro

Duchenne Muscular Dystrophy (DMD) is a devastating genetic disease leading to degeneration of skeletal muscles and premature death. How dystrophin absence leads to muscle wasting remains unclear. Here, we describe an optimized protocol to differentiate human induced Pluripotent Stem Cells (iPSC) to a late myogenic stage. This allows to recapitulate classical DMD phenotypes (mislocalization of proteins of the Dystrophin-glycoprotein associated complex (DGC), increased fusion, myofiber branching, force contraction defects and calcium hyperactivation) in isogenic DMD-mutant iPSC lines in vitro. Treatment of the myogenic cultures with prednisolone (the standard of care for DMD) can dramatically rescue force contraction, fusion and branching defects in DMD iPSC lines. This argues that prednisolone acts directly on myofibers, challenging the largely prevalent view that its beneficial effects are due to anti-inflammatory properties. Our work introduces a new human in vitro model to study the onset of DMD pathology and test novel therapeutic approaches.

cell biology↗

bioRxiv2017

Recapitulating Early Development Of Mouse Musculoskeletal Precursors Of The Paraxial Mesoderm In Vitro

In vertebrates, body skeletal muscles and axial skeleton derive from the paraxial mesoderm which flanks the neural tube and notochord. The paraxial mesoderm forms in the posterior region of the embryo as presomitic mesoderm (PSM), which generates the embryonic segments called somites. Here, we characterized gene signatures identified using microarray series from the mouse PSM and compared the PSM transcriptome dynamics to that of the developing neural tube. In contrast to the PSM where an abrupt transcriptome reorganisation occurs at the level of the determination front, we show that transcriptome changes are progressive during parallel stages of neural tube differentiation. We show that these early differentiation stages of the paraxial mesoderm can be efficiently recapitulated in monolayer culture in vitro using murine Embryonic Stem (ES) cells. We describe a serum-containing protocol which parallels in vivo tissue maturation allowing differentiation of ES cells towards a paraxial mesoderm fate. We show that R-spondin treatment or Wnt activation alone can induce posterior PSM markers in both mouse and human ES/iPS cells but acquisition of a committed posterior PSM fate requires BMP inhibition to prevent induced cells to drift to a lateral plate mesoderm identity. We show that posterior PSM-like cells induced from mouse ES cells can be further differentiated in vitro to acquire an anterior PSM Pax3-positive identity. When grafted into injured adult muscle, these induced PSM-like precursors generated large numbers of immature muscle fibers. We further show that exposing ES-derived PSM-like cells to a brief FGF inhibition step followed by culture in horse serum-containing medium allows efficient recapitulation of the myogenic program. Differentiating ES cells first produce mononucleated embryonic myocytes and subsequently multinucleated myotubes, as well as Pax7-positive cells. The protocol described here results in improved differentiation and maturation of mouse muscle fibers differentiated in vitro over serum-free protocols. It provides an efficient system for the study of myogenic processes otherwise difficult to study in vivo such as fusion or satellite cell differentiation.

developmental biology↗

bioRxiv2017

Warburg-like metabolism coordinates FGF and Wnt signaling in the vertebrate embryo

Mammalian embryos transiently exhibit aerobic glycolysis (Warburg effect), a metabolic adaptation also observed in cancer cells. The role of this particular type of metabolism during vertebrate organogenesis is currently unknown. Here, we provide evidence for spatio-temporal regulation of aerobic glycolysis in the posterior region of mouse and chicken embryos. We show that a posterior glycolytic gradient is established in response to graded transcription of glycolytic enzymes downstream of FGF signaling. We demonstrate that glycolysis controls posterior elongation of the embryonic axis by regulating cell motility in the presomitic mesoderm and by controlling specification of the paraxial mesoderm fate in the tail bud. Our results suggest that Warburg metabolism in the tail bud coordinates Wnt and FGF signaling to promote elongation of the embryonic axis.

developmental biology↗