Project description:The lateral plate mesoderm (LPM) is a transient tissue that produces a diverse range of differentiated structures, including the limbs. However, the molecular mechanisms that drive early LPM specification and development are poorly understood. In this study, we utilize single-cell transcriptomics to define the cell-fate decisions directing LPM specification, subdivision, and early initiation of the forelimb mesenchyme in chicken embryos. We establish a transcriptional atlas and global cell-cell signalling interactions in progenitor, transitional and mature cell types throughout the developing forelimb field.
Project description:Recently, we demonstrated that craniofacial skin, including dermis, epidermis, and hair, can be derived by manipulating signaling factors to co-induce epidermal-dermal progenitors. Here, we advance this approach by controlling the size and composition of cranial skin organoids (cSkOs) and incorporating lateral plate mesoderm (LPM) cells to create ventral skin organoids (vSkOs) and human amnion-like structures, termed Amnioids. Amnioids, resembling their extra-embryonic counterparts, are avascular and rapidly expand into large, hairless cysts, while vSkOs develop primitive vasculature and numerous hair follicles. Single-cell RNA sequencing identified distinct gene expression patterns and developmental trajectories, revealing the critical roles of Wnt and YAP/Hippo signaling in directing divergent fates. Functional experiments underscored the importance of mechanical forces and mesenchymal-epithelial interactions in shaping tissue growth and organization. This study presents a novel in vitro model to explore the interface of embryonic and extraembryonic tissues, with implications for understanding congenital disorders and advancing regenerative medicine.
Project description:The lung mesenchyme plays important roles in lung development and is affected in many respiratory diseases, yet relatively little is known about the biology of lung mesenchymal progenitors. We sought to establish an induced pluripotent stem cell (iPSC)-based model to study lung mesenchyme development and epithelial-mesenchymal interactions. We generated a mouse iPSC line carrying a lung mesenchyme-specific reporter/tracer to establish a protocol for differentiation into lung mesenchymal progenitors. We derived lung mesenchyme from iPSCs both by directed differentiation via a lateral plate mesodermal progenitor state (induced lung mesenchyme, iLM), and by co-development during lung epithelial differentiation (co-developed lung mesenchyme, cLM). We found that directed differentiation via a lateral plate mesoderm progenitor was not only more efficient, but also yielded engineered lung mesenchymal cells that were more similar to primary lung mesenchyme from day 12.5 mouse embryos, as determined by single cell RNAseq. Our iPSC-derived population will provide an inexhaustible source of cells for studying lung development, modeling diseases, and developing therapeutics.
Project description:The vertebrate forelimb initiates as a localized swelling in the somatic lateral plate mesoderm (somatic LPM) in response to Tbx5-dependent transcription. The molecular pathways driving limb morphogenesis have been extensively studied but the steps directly preceding limb bud formation remain poorly characterized. To address this, we defined the temporal onset of forelimb initiation in mouse embryos using sequencing based high-throughput approaches (RNA-seq, scRNA-seq, ChIP-seq, and Ribo-ITP) benchmarked to known features in forelimb development, identifying four distinct stages. Using scRNA-seq at the onset of forelimb-specific transcription, we determined the transcriptional profile of the somatic LPM and identified signature genes that distinguish the nascent forelimb from other cell types. This group includes multiple genes involved in neural projection as well as cell adhesion. Interestingly, these genes are highly enriched for TBX5 binding sites, suggesting they are candidate early transcriptional targets of TBX5. As TBX5 is essential for forelimb outgrowth, the identification of these genes suggests new mechanistic models for TBX5-driven limb initiation.
Project description:The vertebrate forelimb initiates as a localized swelling in the somatic lateral plate mesoderm (somatic LPM) in response to Tbx5-dependent transcription. The molecular pathways driving limb morphogenesis have been extensively studied but the steps directly preceding limb bud formation remain poorly characterized. To address this, we defined the temporal onset of forelimb initiation in mouse embryos using sequencing based high-throughput approaches (RNA-seq, scRNA-seq, ChIP-seq, and Ribo-ITP) benchmarked to known features in forelimb development, identifying four distinct stages. Using scRNA-seq at the onset of forelimb-specific transcription, we determined the transcriptional profile of the somatic LPM and identified signature genes that distinguish the nascent forelimb from other cell types. This group includes multiple genes involved in neural projection as well as cell adhesion. Interestingly, these genes are highly enriched for TBX5 binding sites, suggesting they are candidate early transcriptional targets of TBX5. As TBX5 is essential for forelimb outgrowth, the identification of these genes suggests new mechanistic models for TBX5-driven limb initiation.