REST is a major negative regulator of endocrine differentiation during pancreas organogenesis.

Meritxell Rovira,Jorge Ferrer,Vane Grau,Francois Pattou,Goutham Atla,Jose Luis Mosquera,Javier García-Hurtado,Yasuhiro Yamada,Miguel Angel Maestro,Maria Maqueda,Julie Kerr-Conte

doi:10.1101/gad.348501.121

Abstract

Multiple transcription factors have been shown to promote pancreatic β-cell differentiation, yet much less is known about negative regulators. Earlier epigenomic studies suggested that the transcriptional repressor REST could be a suppressor of endocrinogenesis in the embryonic pancreas. However, pancreatic Rest knockout mice failed to show abnormal numbers of endocrine cells, suggesting that REST is not a major regulator of endocrine differentiation. Using a different conditional allele that enables profound REST inactivation, we observed a marked increase in pancreatic endocrine cell formation. REST inhibition also promoted endocrinogenesis in zebrafish and mouse early postnatal ducts and induced β-cell-specific genes in human adult duct-derived organoids. We also defined genomic sites that are bound and repressed by REST in the embryonic pancreas. Our findings show that REST-dependent inhibition ensures a balanced production of endocrine cells from embryonic pancreatic progenitors.

Highlights

Progress in our understanding of the transcriptional mechanisms underlying pancreatic β-cell differentiation has been crucial for recent advances in the development of regenerative therapy strategies for type 1 diabetes mellitus, including efforts to generate functional β cells from stem cells, organoids, or in vivo reprograming (Rezania et al 2014; Huch and Koo 2015; Zhou and Melton 2018)
We found nuclear repressor element silencing transcription factor (REST) immunoreactivity in most nonendocrine epithelial and mesenchymal cells of the mouse E12.5 pancreas, whereas from E14.5 onward it was largely restricted to duct-like clusters, and absent from acinar and endocrine cell clusters (Supplemental Fig. S1A)
Single-cell RNA-seq data (Tabula Muris et al 2018) showed Rest mRNA in adult duct and nonepithelial cells but not in acinar or endocrine cells (Supplemental Fig. S1D). These results reinforce the notion that REST is expressed in embryonic bipotent progenitors and adult pancreatic ductal cells but is not detected in endocrine cells, consistent with a potential function of REST as a negative regulator of pancreatic endocrine differentiation

Summary

Introduction

Progress in our understanding of the transcriptional mechanisms underlying pancreatic β-cell differentiation has been crucial for recent advances in the development of regenerative therapy strategies for type 1 diabetes mellitus, including efforts to generate functional β cells from stem cells, organoids, or in vivo reprograming (Rezania et al 2014; Huch and Koo 2015; Zhou and Melton 2018). REST binding sites in embryonic stem cells overlap with genomic regions that carry Polycomb-repressed chromatin in FACS-purified multipotent progenitors of the early embryonic pancreas (van Arensbergen et al 2010) Many of these Polycomb-repressed regions are β-cell regulatory genes that are subsequently derepressed during pancreatic endocrine differentiation, in parallel with the concomitant loss of REST expression (van Arensbergen et al 2010). Cre/LoxP-based excision of Rest in pancreatic progenitors led to changes in the expression of some endocrine genes but did not affect the number of endocrine cells, suggesting it was not an essential modulator of endocrine differentiation (Martin et al 2015) Another pancreas deletion study reported that REST tempers pancreatic tissue damage and prevents acinoductal metaplasia, but the study did not explicitly assess endocrine differentiation (Bray et al 2020). Warrant a need to explore the true impact of REST in pancreatic endocrine differentiation using alternative genetic tools

Methods

Results

Conclusion