A BAC transgenic Hes1-EGFP reporter reveals novel expression domains in mouse embryos

Abstract

Expression of the basic helix-loop-helix factor Hairy and Enhancer of Split-1 (Hes1) is required for normal development of a number of tissues during embryonic development. Depending on context, Hes1 may act as a Notch signalling effector which promotes the undifferentiated and proliferative state of progenitor cells, but increasing evidence also points to Notch independent regulation of Hes1 expression. Here we use high resolution confocal scanning of EGFP in a novel BAC transgenic mouse reporter line, Tg(Hes1-EGFP)1Hri, to analyse Hes1 expression from embryonic day 7.0 (e7.0). Our data recapitulates some previous observations on Hes1 expression and suggests new, hitherto unrecognised expression domains including expression in the definitive endoderm at early somite stages before gut tube closure and thus preceding organogenesis. This mouse line will be a valuable tool for studies addressing the role of Hes1 in a number of different research areas including organ specification, development and regeneration.

Genetic visualization of notch signaling in mammalian neurogenesis

“…3c) [60]. Immunofluorescent staining for Hes1 and EGFP on adjacent sections confirmed co-expression of EGFP with Hes1 in progenitor cells of the developing nervous system.…”

Ptf1a-mediated control of Dll1 reveals an alternative to the lateral inhibition mechanism

“…To test predictions of the classical lateral inhibition model we first used immunofluorescence (IF) to map the expression patterns of Dll1, NICD and Hes1 expression, relying on the -galactosidase (-gal) and EGFP reporters in Dll1 tm1Gos/+ (Dll1 lacZ/+ hereafter) mice (Hrabe de Angelis et al, 1997) and Tg(Hes1-EGFP) 1Hri BAC transgenic mice (Klinck et al, 2011), respectively. We found -gal expression in presomitic mesoderm and nascent somites in E8.25 embryos (Fig.…”

“…Additionally, our data demonstrate that Ptf1a via activation of Dll1 stimulates MPC proliferation and contributes to Hes1 activation, and thereby may indirectly contribute to maintaining high Ptf1a protein levels. BAC transgenic (Klinck et al, 2011), Neurog3 tTA/+ (Wang et al, 2009)…”

Jag1 modulates an oscillatory Dll1-Notch-Hes1 signaling module to coordinate growth and fate of pancreatic progenitors

“…Since this reporter is specific to Notch1, we next analyzed Hes1 expression as a general, pan-Notch acute readout. We bred mice harboring the Hes1-EGFP reporter 24 to the Jag1 J1VmC and Dll1 D1VmC lines and assayed for EGFP expression using an antibody that only detects the high levels of (cytoplasmic) EGFP derived from the Hes1-EGFP reporter, but not the low levels of (membrane-associated) Jag1-Venus or Dll1-Venus fusion proteins ( Fig. 2e-n).…”

“…Notch signaling, and its downstream target gene Hes1, have previously been shown to prevent precocious and excessive endocrine differentiation 20,21 , and independently of this also stimulate MPC proliferation 22 . After PD patterning is complete at around E14, Notch signaling and Hes1 expression persist in BPs where they maintain Sox9 expression and ductal fate, and inhibit endocrine differentiation by repressing Neurog3 [23][24][25][26][27] . Less is known about which ligands regulate the adoption of distinct cell fates.…”