Intercellular genetic tracing of cardiac endothelium in the developing heart

Hippo pathway in cell–cell communication: emerging roles in development and regeneration

“…As highlighted in this review, the non-cell-autonomous functions of the Hippo pathway in mammals have been elucidated by taking advantage of recent developments in single-cell analysis and/or the introduction of sporadic Hippo mutations in tissues. Notably, recent advances in the genetic tracing of cell–cell contacts using the synthetic Notch (synNotch) system, which utilizes artificial Notch ligand–receptor interaction to induce gene expression upon cell–cell contact [ 121 , 122 ], and the photo-isolation chemistry (PIC) system, which enables the isolation of transcriptome profiles from photo-irradiated regions of interest [ 123 ], have revealed an unexpected broad cell–cell interaction history during development. Future studies clarifying the role of the Hippo pathway in these intercellular communications during development and regeneration may not only contribute to a better understanding of this pathway but also open new avenues for future therapeutic strategies targeting the Hippo pathway.…”

Application of New Lineage Tracing Techniques in Cardiovascular Development and Physiology

“…72 Furthermore, specific labeling of cardiac ECs including endocardial cells in the developing heart helps resolve a recent controversy over the hematopoietic potential of the developing endocardium. [73][74][75][76] The cardiac ECs that have contacted with cardiomyocytes can be permanently labeled with a genetic reporter (Figure 4D). However, these labeled cardiac ECs did not contribute to hematopoietic cells such as macrophages of the heart or circulating blood cells, suggesting that developing cardiac ECs do not have endogenous hematopoietic potential.…”

“…However, these labeled cardiac ECs did not contribute to hematopoietic cells such as macrophages of the heart or circulating blood cells, suggesting that developing cardiac ECs do not have endogenous hematopoietic potential. 76 As our understanding of cellular heterogeneity deepens, by virtue of single-cell transcriptomics, the identification of cell (sub)types solely by singular markers remains challenging. To specifically label cell (sub)types in vivo, intercellular lineage tracing offers an alternative orthogonal method that allows the tracing of neighboring cell types in a specific anatomic location, providing a more precise mapping approach for cell lineages within a niche even without knowing their specific gene signatures.…”

Enabling neighbour labelling: using synthetic biology to explore how cells influence their neighbours

“…This resulted in contact-mediated synthetic patterning of two distinct cell types (a stripe of neurons across a field of pluripotent cells) without the need for an exogenous differentiation regime ( Malaguti et al, 2022 ). In a particularly impressive feat of bioengineering, synNotch has been used to generate Crispr-engineered mouse lines to either monitor cell interactions in real time or to track the history of interactions over developmental time, using cell contact to induce Cre recombinase (rather than a fluorescent label) and combining this with Cre-dependent lineage labelling ( Liu et al, 2023 ; Zhang et al, 2022 ) (see also below).…”

“…Upon expression of Flp recombinase by a lineage-specific and/or inducible promoter, the synNotch receptor is excised from the genome through Flp/FRT recombination, and the synNotch ligand is expressed in its place, converting Flp-expressing cells into ‘sender’ cells, which in turn label their ‘receiver’ neighbours ( He et al, 2017 ). A similar strategy, involving Cre/loxP recombination in place of Flp/FRT recombination, was adopted by Zhou and colleagues in mouse embryos ( Liu et al, 2023 ; Zhang et al, 2022 ). By crossing these organisms with promoter-specific Flp/Cre-driver lines, these ‘all-in-one’ systems offer great modularity for identifying neighbours of any cell type of interest, without the need for recurrent genetic targeting of synNotch receptors and ligand to different promoters to avoid cis -inhibition ( Fig.…”