Notch Controls Multiple Pancreatic Cell Fate Regulators Through Direct Hes1-mediated Repression

Abstract

AbstractNotch signaling and its effector Hes1 regulate multiple cell fate choices in the developing pancreas, but few direct target genes are known. Here we use transcriptome analyses combined with chromatin immunoprecipitation with next-generation sequencing (ChIP-seq) to identify direct target genes of Hes1. ChIP-seq analysis of endogenous Hes1 in 266-6 cells, a model of multipotent pancreatic progenitor cells, revealed high-confidence peaks associated with 354 genes. Among these were genes important for tip/trunk segregation such asPtf1aandNkx6-1, genes involved in endocrine differentiation such asInsm1andDll4, and genes encoding non-pancreatic basic-Helic-Loop-Helix (bHLH) factors such asNeurog2andAscl1. Surprisingly, we find that Hes1 binds a large number of loci previously reported to bind Ptf1a, including a site downstream of theNkx6-1gene. Notably, we find a number of Hes1 bound genes that are upregulated by γ-secretase inhibition in pancreas explants independently ofNeurog3function, including the tip progenitor/acinar genes;Ptf1a, Gata4, Bhlha15, andGfi1. Together, our data suggest that Notch signaling suppress the tip cell fate by Hes1-mediated repression of the tip-specific gene regulatory network module that includes transcriptional regulators such as Ptf1a, Gata4, Mist1, and Gfi1. Our data also uncover new molecular targets of Notch signaling that may be important for controlling cell fate choices in pancreas development.