Endocrine lineage biases arise in temporally distinct endocrine progenitors during pancreatic morphogenesis

Abstract

Decoding the molecular composition of individual Ngn3 + endocrine progenitors (EPs) during pancreatic morphogenesis could provide insight into the mechanisms regulating hormonal cell fate. Here, we identify population markers and extensive cellular diversity including four EP subtypes reflecting EP maturation using high-resolution single-cell RNA-sequencing of the e14.5 and e16.5 mouse pancreas. While e14.5 and e16.5 EPs are constantly born and share select genes, these EPs are overall transcriptionally distinct concomitant with changes in the underlying epithelium. As a consequence, e16.5 EPs are not the same as e14.5 EPs: e16.5 EPs have a higher propensity to form beta cells. Analysis of e14.5 and e16.5 EP chromatin states reveals temporal shifts, with enrichment of beta cell motifs in accessible regions at later stages. Finally, we provide transcriptional maps outlining the route progenitors take as they make cell fate decisions, which can be applied to advance the in vitro generation of beta cells.

Pancreatic development: one cell at a (pseudo)time

“…Consistent with previous findings, EP cells present from E13.5 to E15.5 contain multiple intermediate stages (Scavuzzo et al , ). In this paper, seven subgroups of 670 genes are found to be distinctly expressed in four transient EP stages, termed EP1 through 4, which represent progressively more mature EP states (Fig B).…”

Analysis of Differentiation Protocols Defines a Common Pancreatic Progenitor Molecular Signature and Guides Refinement of Endocrine Differentiation

“…In line with this, we found that the CUX2 gene's expression during differentiation peaks at the pancreatic endoderm stage, and we observed evidence for CUX2 being bound within the open chromatin of the samples generated in this study through ATAC-seq footprinting analysis. Interestingly, a previous study demonstrated the expression of CUX2 in early fetal human dorsal pancreas (Jennings et al, 2017), and more recently the presence of CUX2 motifs in accessible chromatin regions were shown to be differentially enriched in mouse endocrine progenitors across different stages of development (Scavuzzo et al, 2018). Based on this evidence, we suggest CUX2 as a potential novel regulator of pancreatic development.…”

Defining multistep cell fate decision pathways during pancreatic development at single‐cell resolution

“…A recent study generated 15,228 single‐cell datasets from E14.5 pancreas using a droplet‐based method and defined four subpopulations. The heterogeneity of EP cells was verified using the differentially expressed genes (Scavuzzo et al , ). However, the second subpopulation (a small population marked by “N14_2”), which expressed the mesenchymal cell marker gene Col3a1 , deviated from the developmental trajectory of other three subpopulations (Scavuzzo et al , ).…”