Defining Pancreatic Endocrine Precursors and Their Descendants

Abstract

OBJECTIVE—The global incidence of diabetes continues to increase. Cell replacement therapy and islet transplantation offer hope, especially for severely affected patients. Efforts to differentiate insulin-producing β-cells from progenitor or stem cells require knowledge of the transcriptional programs that regulate the development of the endocrine pancreas. RESEARCH DESIGN AND METHODS—Differentiation toward the endocrine lineage is dependent on the transcription factor Neurogenin 3 (Neurog3, Ngn3). We utilize a Neurog3–enhanced green fluorescent protein knock-in mouse model to isolate endocrine progenitor cells from embryonic pancreata (embryonic day [E]13.5 through E17.5). Using advanced genomic approaches, we generate a comprehensive gene expression profile of these progenitors and their immediate descendants. RESULTS—A total of 1,029 genes were identified as being temporally regulated in the endocrine lineage during fetal development, 237 of which are transcriptional regulators. Through pathway analysis, we have modeled regulatory networks involving these proteins that highlight the complex transcriptional hierarchy governing endocrine differentiation. CONCLUSIONS—We have been able to accurately capture the gene expression profile of the pancreatic endocrine progenitors and their descendants. The list of temporally regulated genes identified in fetal endocrine precursors and their immediate descendants provides a novel and important resource for developmental biologists and diabetes researchers alike.

The transcriptional co-repressor Grg3/Tle3 promotes pancreatic endocrine progenitor delamination and β-cell differentiation

“…3I). In these embryos, eGFP activated in Ngn3 + endocrine progenitors persists in newly formed Ngn3 -endocrine cells (Lee et al, 2002;White et al, 2008). We found that Grg3 marks the majority of Ngn3 -/GFP+ cells (orange arrows, 86%), marking 68% of the total GFP+ cells (Fig.…”

Sustained Neurog3 expression in hormone-expressing islet cells is required for endocrine maturation and function

“…A sustained low level of Neurog3, after full endocrine differentiation, allows cells to maintain their chromatin structure that favors the expression of genes required for islet cell function. By far, the expression of many genes has been shown to rely on Neurog3 (9,10). However, the absence of a highly specific and high-affinity Neurog3 antibody has prevented the comprehensive study of how Neurog3 interacts with it transcriptional target DNA sequences to regulate gene activity.…”

“…All such endocrine islet cells are derived from Neurog3 ϩ (positive) precursors (1,2) and Neurog3 deficiency virtually abolishes islet cell differentiation (3,4). Moreover, ectopic Neurog3 expression converts early endodermal progenitor cells into endocrine islet cells (5)(6)(7)(8), and Neurog3 controls the expression of multiple genes that influence both endocrine differentiation and function (3,9,10). Because Neurog3 has not been detected in differentiated islet cells, its expression in the adult pancreas is proposed as a marker for putative endocrine progenitors (2,11).…”

Chronology of endocrine differentiation and beta-cell neogenesis [Review]

“…Various mouse models expressing fluorescent proteins, such as eGFP and Ds-Red, have been developed to label specific cell populations, and Neurog3-eGFP mouse lines, which express eGFP under the control of the Neuorg3 promoter, have been generated to distinguish endocrine cells from other cell types, such as acinar cells and endothelial cells [21,22]. Although Neurog3-eGFP mouse lines enable us to investigate gene expression profiles in the cells that have commit- …”