Lineage labeling with zebrafish Cre and CreERT2 recombinase CRISPR knock-ins.

BACKGROUND

The ability to generate endogenous Cre recombinase drivers using CRISPR-Cas9 knock-in technology allows lineage tracing, cell type specific gene studies, and validation of inferred developmental trajectories from phenotypic and gene expression analyses. This report describes endogenous zebrafish Cre and CreERT2 drivers generated with GeneWeld CRISPR-Cas9 precision targeted integration.

RESULTS

and knock-ins crossed with ubiquitous -based Switch reporters led to broad labeling in expected mesodermal and neural crest-derived lineages in cardiac, pectoral fins, pharyngeal arch, liver, intestine, and mesothelial tissues, as well as enteric neurons. Novel patterns of lineage tracing appeared in venous blood vessels. CreERT2 induction at 24 hours reveals late emerging progenitors in the 24 - 48 hour embryo contribute to the venous and intestinal vasculature. Induction in 3 dpf larva restricts lineage labeling to mesoderm-derived components of the branchial arches, heart, liver and enteric neurons.

CONCLUSIONS

progenitors from the lateral plate mesoderm and ectoderm contribute to numerous lineages in the developing embryo. Later emerging progenitors become restricted to a subset of lineages in the larva. The Cre and CreERT2 drivers establish critical new tools to investigate lineages in zebrafish embryogenesis and larval organogenesis.