Sequential progenitor states mark the generation of pancreatic endocrine lineages in mice and humans

The pancreatic islet contains multiple hormone(+) endocrine lineages (alpha, beta, delta, PP and epsilon cells), but the developmental processes that underlie endocrinogenesis are poorly understood. Here, we generated novel mouse lines and combined them with various genetic tools to enrich all types of hormone(+) cells for well-based deep single-cell RNA sequencing (scRNA-seq), and gene coexpression networks were extracted from the generated data for the optimization of high-throughput droplet-based scRNA-seq analyses. These analyses defined an entire endocrinogenesis pathway in which different states of endocrine progenitor (EP) cells sequentially differentiate into specific endocrine lineages in mice. Subpopulations of the EP cells at the final stage (EP4(early) and EP4(late)) show different potentials for distinct endocrine lineages. epsilon cells and an intermediate cell population were identified as distinct progenitors that independently generate both alpha and PP cells. Single-cell analyses were also performed to delineate the human pancreatic endocrinogenesis process. Although the developmental trajectory of pancreatic lineages is generally conserved between humans and mice, clear interspecies differences, including differences in the proportions of cell types and the regulatory networks associated with the differentiation of specific lineages, have been detected. Our findings support a model in which sequential transient progenitor cell states determine the differentiation of multiple cell lineages and provide a blueprint for directing the generation of pancreatic islets in vitro.

Automated summary

Utilizing novel mouse lines and genetic tools, this study conducted deep single-cell RNA sequencing of pancreatic hormone cells to reveal the pathway of endocrinogenesis and differentiation of various endocrine lineages. The research identified ε cells and an intermediate cell population as distinct progenitors for α and PP cells and detected interspecies differences in the developmental process of pancreatic lineages between humans and mice.