TGF-β modulates cell fate in human ES cell-derived foregut endoderm by inhibiting Wnt and BMP signaling.

Genetic differences between pluripotent stem cell lines cause variable activity of extracellular signaling pathways, limiting reproducibility of directed differentiation protocols. Here we used human embryonic stem cells (hESCs) to interrogate how exogenous factors modulate endogenous signaling events during specification of foregut endoderm lineages. We find that transforming growth factor β1 (TGF-β1) activates a putative human OTX2/LHX1 gene regulatory network which promotes anterior fate by antagonizing endogenous Wnt signaling.

Jag1-Notch cis-interaction determines cell fate segregation in pancreatic development.

The Notch ligands Jag1 and Dll1 guide differentiation of multipotent pancreatic progenitor cells (MPCs) into unipotent pro-acinar cells (PACs) and bipotent duct/endocrine progenitors (BPs). Ligand-mediated trans-activation of Notch receptors induces oscillating expression of the transcription factor Hes1, while ligand-receptor cis-interaction indirectly represses Hes1 activation. Despite Dll1 and Jag1 both displaying cis- and trans-interactions, the two mutants have different phenotypes for reasons not fully understood.

Canonical Notch signaling controls the early thymic epithelial progenitor cell state and emergence of the medullary epithelial lineage in fetal thymus development.

Thymus function depends on the epithelial compartment of the thymic stroma. Cortical thymic epithelial cells (cTECs) regulate T cell lineage commitment and positive selection, while medullary (m) TECs impose central tolerance on the T cell repertoire. During thymus organogenesis, these functionally distinct sub-lineages are thought to arise from a common thymic epithelial progenitor cell (TEPC).

Jag1 Modulates an Oscillatory Dll1-Notch-Hes1 Signaling Module to Coordinate Growth and Fate of Pancreatic Progenitors.

Notch signaling controls proliferation of multipotent pancreatic progenitor cells (MPCs) and their segregation into bipotent progenitors (BPs) and unipotent pro-acinar cells (PACs). Here, we showed that fast ultradian oscillations of the ligand Dll1 and the transcriptional effector Hes1 were crucial for MPC expansion, and changes in Hes1 oscillation parameters were associated with selective adoption of BP or PAC fate. Conversely, Jag1, a uniformly expressed ligand, restrained MPC growth.

Neurog3-dependent pancreas dysgenesis causes ectopic pancreas in mutant mice.

Mutations in , a target gene of the Notch signalling pathway, lead to ectopic pancreas by a poorly described mechanism. Here, we use genetic inactivation of combined with lineage tracing and live imaging to reveal an endodermal requirement for Hes1, and show that ectopic pancreas tissue is derived from the dorsal pancreas primordium. RNA-seq analysis of sorted E10.

The Prdm13 histone methyltransferase encoding gene is a Ptf1a-Rbpj downstream target that suppresses glutamatergic and promotes GABAergic neuronal fate in the dorsal neural tube.

The basic helix-loop-helix (bHLH) transcriptional activator Ptf1a determines inhibitory GABAergic over excitatory glutamatergic neuronal cell fate in progenitors of the vertebrate dorsal spinal cord, cerebellum and retina. In an in situ hybridization expression survey of PR domain containing genes encoding putative chromatin-remodeling zinc finger transcription factors in Xenopus embryos, we identified Prdm13 as a histone methyltransferase belonging to the Ptf1a synexpression group. Gain and loss of Ptf1a function analyses in both frog and mice indicates that Prdm13 is positively regulated by Ptf1a and likely constitutes a direct transcriptional target.

Mind bomb 1 is required for pancreatic β-cell formation.

During early pancreatic development, Notch signaling represses differentiation of endocrine cells and promotes proliferation of Nkx6-1(+)Ptf1a(+) multipotent progenitor cells (MPCs). Later, antagonistic interactions between Nkx6 transcription factors and Ptf1a function to segregate MPCs into distal Nkx6-1(-)Ptf1a(+) acinar progenitors and proximal Nkx6-1(+)Ptf1a(-) duct and β-cell progenitors. Distal cells are initially multipotent, but evolve into unipotent, acinar cell progenitors.

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

Neurog3-induced Dll1 expression in pancreatic endocrine progenitors ostensibly activates Hes1 expression via Notch and thereby represses Neurog3 and endocrine differentiation in neighboring cells by lateral inhibition. Here we show in mouse that Dll1 and Hes1 expression deviate during regionalization of early endoderm, and later during early pancreas morphogenesis. At that time, Ptf1a activates Dll1 in multipotent pancreatic progenitor cells (MPCs), and Hes1 expression becomes Dll1 dependent over a brief time window.

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

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.

Retinoic acid signaling organizes endodermal organ specification along the entire antero-posterior axis.

Background: Endoderm organ primordia become specified between gastrulation and gut tube folding in Amniotes. Although the requirement for RA signaling for the development of a few individual endoderm organs has been established a systematic assessment of its activity along the entire antero-posterior axis has not been performed in this germ layer.

Methodology/principal Findings: RA is synthesized from gastrulation to somitogenesis in the mesoderm that is close to the developing gut tube.

Specificity of four monoclonal anti-NKx6-1 antibodies.

The homeodomain transcription factor Nkx6-1 is essential for proper motor neuron development and development of insulin-producing pancreatic beta-cells. Nkx6-1 is closely related to Nkx6-2 and Nkx6-3, and all three are expressed in the developing central nervous system and in the developing foregut. Immunohistochemical detection of protein expression is an important tool for description of the temporal differences in expression patterns.

An illustrated review of early pancreas development in the mouse.

Pancreas morphogenesis and cell differentiation are highly conserved among vertebrates during fetal development. The pancreas develops through simple budlike structures on the primitive gut tube to a highly branched organ containing many specialized cell types. This review presents an overview of key molecular components and important signaling sources illustrated by an extensive three-dimensional (3D) imaging of the developing mouse pancreas at single cell resolution.

An improved method for three-dimensional reconstruction of protein expression patterns in intact mouse and chicken embryos and organs.

We have developed a wholemount immunofluorescence protocol for the simultaneous detection of up to three proteins in mouse and chicken embryos. Combined with Murray's clearing reagent (BABB) and microscope objectives with long working ranges and high numerical apertures mounted on a confocal microscope, cellular resolution can be obtained in depths offering the possibility of examining expression patterns in entire organs or embryos. Three-dimensional projections of the optical confocal sections can be computed with computer software allowing rotation around any axis.

Generation and characterization of monoclonal antibodies against the transcription factor Nkx6.1.

We present the generation of a panel of monoclonal antibodies (F55A10, F55A12, F64A6B4, and F65A2) against the homeodomain transcription factor Nkx6.1, one of the essential transcription factors that regulates the multistep differentiation process of precursor cells into endocrine beta-cells in the pancreas. Expression of Nkx6.

Endodermal expression of Nkx6 genes depends differentially on Pdx1.

Nkx family members are essential for normal development of many different tissues such as the heart, lungs, thyroid, prostate, and CNS. Here, we describe the endodermal expression pattern of three Nkx6 family genes of which two shows conserved expression in the early pancreatic epithelium. In chicken, Nkx6.