Nandkishore, N. | Search bioRxiv

bioRxiv2025

Temporal requirements of MAPK effectors reflect signalling microenvironment heterogeneity during Mesp1+ cardiac progenitor emergence and migration.

During mouse gastrulation, cardiac progenitors arise within dynamic morphogenetic landscapes, yet the mechanisms by which the progenitors integrate this information and respond to it remain unclear. We profiled candidate signalling ligands in wild-type and Mesp1 mutant embryos, which display defective progenitor migration. In Mesp1 progenitors, Fgf and Wnt ligand expression changes over gastrulation, coinciding with the emergence of first and second heart fields (FHF, SHF). This temporal pattern is perturbed in Mesp1 mutants. Signal inhibition studies in embryos, cultured ex utero, reveal a role for intracellular signalling effectors in mediating the proper migration of the cardiac progenitors. We demonstrate that the different branches of the MAPK signalling effectors (p38, ERK, JNK) are required in distinct temporal windows for proper migration. Our findings link the heterogeneous signalling environment of the cardiac fields to stage-specific MAPK requirements, offering insight into how progenitors integrate complex environmental inputs to coordinate fate specification and migration.

developmental biology↗

bioRxiv2023

Cardiopharyngeal Mesoderm specification into cardiac and skeletal muscle lineages in gastruloids.

Cardiopharyngeal mesoderm contributes to the formation of the heart and head muscles. However, the mechanisms governing cardiopharyngeal mesoderm specification remain unclear. Indeed, there is a lack of an in vitro model replicating the differentiation of both heart and head muscles to study these mechanisms. Such models are required to allow live-imaging and high throughput genetic and drug screening. Here, we show that the formation of self-organizing or pseudo-embryos from mouse embryonic stem cells (mESCs), also called gastruloids, reproduces cardiopharyngeal mesoderm specification towards cardiac and skeletal muscle lineages. By conducting a comprehensive temporal analysis of cardiopharyngeal mesoderm establishment and differentiation in gastruloids and comparing it to mouse embryos, we present the first evidence for skeletal myogenesis in gastruloids. By inferring lineage trajectories from the gastruloids single-cell transcriptomic data, we further suggest that heart and head muscles formed in gastruloids derive from cardiopharyngeal mesoderm progenitors. We identify different subpopulations of cardiomyocytes and skeletal muscles, which most likely correspond to different states of myogenesis with "head-like" and "trunk-like" skeletal myoblasts. These findings unveil the potential of mESC-derived gastruloids to undergo specification into both cardiac and skeletal muscle lineages, allowing the investigation of the mechanisms of cardiopharyngeal mesoderm differentiation in development and how this could be affected in congenital diseases.

developmental biology↗