Developing a spatiotemporal lineage map of heart development - Project Summary Heart malformations are the most common form of serious birth defect, with more than 1% having congenital heart disease (CHD)1, and about 1 in 4 of these requiring an interventional procedure in the first year of life2. As a result, extensive efforts have been made to understand normal heart development and how it is perturbed by genetic or environmental insults3. A small number of cardiac progenitor cells, marked by the expression of MESP1, differentiate into the many cell types of the heart. Clonal analyses have outlined relationships between these progenitor populations, as well as their ultimate contribution to the major differentiated cell types of the heart10,11. Due to technical limitations, these lineage maps are incomplete, lacking clear connections between major progenitor populations as well as information about intermediate steps of lineage diversification of cardiac cells. Building on revolutionary lineage tracing, spatial, and transcriptomic technologies with single cell resolution, we will create a high-resolution spatiotemporal lineage map of cardiac development. Furthermore, we will deploy this approach to investigate how gene mutations that cause cardiac malformations disrupt cardiac lineage specification and result in congenital heart disease. We will pursue the following Specific Aims: Aim 1. To spatiotemporally map early cardiac progenitor lineages and their clonal relationships. Aim 2. To spatiotemporally map the phylogeny of the major myocardial cell types. Aim 3. To define the effect of Tbx5 knockout on cardiac lineage diversification. This proposal will produce a high-resolution spatiotemporal lineage map of cardiac development. Our studies of Tbx5 inactivation within this framework will illustrate its utility for studying the mechanisms by which genetic or environmental insults cause heart malformations. The methods and analytical tools developed in this project will have widespread applications in other fields of developmental biology as well as heart regeneration and acquired heart disease.
