AI Insight
Researchers developed a dual reporter mouse embryonic stem cell line to study neuromesodermal progenitors (NMPs), cells that generate both the spinal cord and skeletal muscle during embryonic development. Using live imaging and clonal analysis, they discovered that NMPs are more heterogeneous than previously thought, with varying levels of the transcription factors SOX2 and TBXT determining whether cells become neural tissue or mesoderm. Contrary to the prevailing model, the study found that SOX2 and TBXT act independently rather than antagonistically to control cell fate decisions, with specific expression thresholds switching cells from neural-biased to mesoderm-biased and finally to mesoderm-specified states.
Why it matters
This research provides new insights into how the embryonic body axis forms and how progenitor cells make fate decisions, which could improve methods for generating specific cell types from stem cells in regenerative medicine. Understanding the quantitative relationship between transcription factor levels and cell fate may enable better control of stem cell differentiation for therapeutic applications.
Understand the Science
by Anahí Binagui-Casas, Anna Granés, Alberto S. Ceccarelli, Matthew French, Filip J. Wymeersch, Rosa Portero Migueles, Jennifer Annoh, Yali Huang, Eleni P. Karagianni, Frederick C. K. Wong, Raffee Wright, A. Sophie Brumm, Daniel Lopez Ramajo, Minoru Takasato, Sally Lowell, Osvaldo Chara, Valerie Wilson
Neuromesodermal progenitors (NMPs) produce the spinal cord and musculoskeleton in the elongating anterior-posterior axis. In vivo, NMPs possess dual potency, coinciding with regions co-expressing SOX2 and Brachyury (TBXT). In vitro, SOX2/TBXT co-expressing cells can be produced from pluripotent cells and, like their in vivo counterparts, can produce neural tube and somitic mesoderm. However, the functional characteristics of in vitro SOX2/TBXT co-expressing cells remain unclear, confounding comparisons with in vivo data. To address this, we developed a dual Sox2/Tbxt reporter mouse ESC line. SOX2/TBXT reporter-positive cells emerge in vitro from pluripotent populations with dynamics that mirror their appearance in the embryo. Purified SOX2/TBXT co-expressing populations can differentiate towards neurectoderm or mesoderm, including lateral mesoderm upon BMP stimulation. In gastruloids, quantitative live imaging shows that WNT or NOTCH inhibition rapidly leads to downregulation of TBXT expression and diminished axial extension. We show that clonally plated SOX2/TBXT co-expressing cells are bipotent NMPs that can also self-propagate. By combining clonal analysis with mathematical inference, we identify two thresholds of TBXT and/or SOX2 expression, switching clonal output from neural- to mesoderm-biased, and from mesoderm-biased to mesoderm-specified. Image analysis of embryonic NMPs supports a model whereby SOX2 and TBXT independently influence neuromesodermal differentiation. Thus, this Sox2/Tbxt double reporter cell line highlights unsuspected heterogeneity in NMPs, and together with image analysis of embryonic SOX2/TBXT levels, challenges the assumption that neuromesodermal fate choice is primarily governed by mutual antagonism between SOX2/TBXT.