Retraction Note: Transient cytokine treatment induces acinar cell reprogramming and regenerates functional beta cell mass in diabetic mice.

This article has been retracted; see accompanying Retraction Note, which can be accessed via a link at the top of the paper.

Point mutations in the PDX1 transactivation domain impair human β-cell development and function.

Objective: Hundreds of missense mutations in the coding region of PDX1 exist; however, if these mutations predispose to diabetes mellitus is unknown.

Methods: In this study, we screened a large cohort of subjects with increased risk for diabetes and identified two subjects with impaired glucose tolerance carrying common, heterozygous, missense mutations in the PDX1 coding region leading to single amino acid exchanges (P33T, C18R) in its transactivation domain. We generated iPSCs from patients with heterozygous PDX1, PDX1 mutations and engineered isogenic cell lines carrying homozygous PDX1, PDX1 mutations and a heterozygous PDX1 loss-of-function mutation (PDX1).

ROCK-nmMyoII, Notch and gene-dosage link epithelial morphogenesis with cell fate in the pancreatic endocrine-progenitor niche.

During mouse pancreas organogenesis, endocrine cells are born from progenitors residing in an epithelial plexus niche. After a period in a lineage-primed state, progenitors become endocrine committed via upregulation of We find that the to transition is associated with distinct stages of an epithelial egression process: narrowing the apical surface of the cell, basalward cell movement and eventual cell-rear detachment from the apical lumen surface to allow clustering as nascent islets under the basement membrane. Apical narrowing, basalward movement and transcriptional upregulation still occur without Neurog3 protein, suggesting that morphogenetic cues deployed within the plexus initiate endocrine commitment upstream or independently of Neurog3.

Genome-wide analysis of PDX1 target genes in human pancreatic progenitors.

Objective: Homozygous loss-of-function mutations in the gene coding for the homeobox transcription factor (TF) PDX1 leads to pancreatic agenesis, whereas heterozygous mutations can cause Maturity-Onset Diabetes of the Young 4 (MODY4). Although the function of Pdx1 is well studied in pre-clinical models during insulin-producing β-cell development and homeostasis, it remains elusive how this TF controls human pancreas development by regulating a downstream transcriptional program. Also, comparative studies of PDX1 binding patterns in pancreatic progenitors and adult β-cells have not been conducted so far.

A Role for Dystonia-Associated Genes in Spinal GABAergic Interneuron Circuitry.

Spinal interneurons are critical modulators of motor circuit function. In the dorsal spinal cord, a set of interneurons called GABApre presynaptically inhibits proprioceptive sensory afferent terminals, thus negatively regulating sensory-motor signaling. Although deficits in presynaptic inhibition have been inferred in human motor diseases, including dystonia, it remains unclear whether GABApre circuit components are altered in these conditions.

FUCCI tracking shows cell-cycle-dependent Neurog3 variation in pancreatic progenitors.

During pancreas organogenesis, Neurog3 endocrine-committing cells are generated from a population of Sox9 mitotic progenitors with only a low level of Neurog3 transcriptional activity (Neurog3 ). Low-level Neurog3 protein, in Neurog3 cells, is required to maintain their mitotic endocrine-lineage-primed status. Herein, we describe a Neurog3-driven FUCCI cell-cycle reporter (Neurog3 ) derived from a Neurog3 BAC transgenic reporter that functions as a loxed cassette acceptor (LCA).

The mammal-specific Pdx1 Area II enhancer has multiple essential functions in early endocrine cell specification and postnatal β-cell maturation.

The transcription factor Pdx1 is required for multiple aspects of pancreatic organogenesis. It remains unclear to what extent Pdx1 expression and function depend upon trans-activation through 5' conserved cis-regulatory regions and, in particular, whether the mammal-specific Area II (-2139 to -1958 bp) affects minor or major aspects of organogenesis. We show that Area II is a primary effector of endocrine-selective transcription in epithelial multipotent cells, nascent endocrine progenitors, and differentiating and mature β cells in vivo Pdx1 mice exhibit a massive reduction in endocrine progenitor cells and progeny hormone-producing cells, indicating that Area II activity is fundamental to mounting an effective endocrine lineage-specification program within the multipotent cell population.

Foxl1-expressing mesenchymal cells constitute the intestinal stem cell niche.

Background & Aims: Intestinal epithelial stem cells that express Lgr5 and/or Bmi1 continuously replicate and generate differentiated cells throughout life. Previously, Paneth cells were suggested to constitute an epithelium-intrinsic niche that regulates the behavior of these stem cells. However, ablating Paneth cells has no effect on maintenance of functional stem cells.

Inactivating the permanent neonatal diabetes gene Mnx1 switches insulin-producing β-cells to a δ-like fate and reveals a facultative proliferative capacity in aged β-cells.

Homozygous Mnx1 mutation causes permanent neonatal diabetes in humans, but via unknown mechanisms. Our systematic and longitudinal analysis of Mnx1 function during murine pancreas organogenesis and into the adult uncovered novel stage-specific roles for Mnx1 in endocrine lineage allocation and β-cell fate maintenance. Inactivation in the endocrine-progenitor stage shows that Mnx1 promotes β-cell while suppressing δ-cell differentiation programs, and is crucial for postnatal β-cell fate maintenance.

Feedback control of growth, differentiation, and morphogenesis of pancreatic endocrine progenitors in an epithelial plexus niche.

In the mammalian pancreas, endocrine cells undergo lineage allocation upon emergence from a bipotent duct/endocrine progenitor pool, which resides in the "trunk epithelium." Major questions remain regarding how niche environments are organized within this epithelium to coordinate endocrine differentiation with programs of epithelial growth, maturation, and morphogenesis. We used EdU pulse-chase and tissue-reconstruction approaches to analyze how endocrine progenitors and their differentiating progeny are assembled within the trunk as it undergoes remodeling from an irregular plexus of tubules to form the eventual mature, branched ductal arbor.

Sensory and spinal inhibitory dorsal midline crossing is independent of Robo3.

Commissural neurons project across the midline at all levels of the central nervous system (CNS), providing bilateral communication critical for the coordination of motor activity and sensory perception. Midline crossing at the spinal ventral midline has been extensively studied and has revealed that multiple developmental lineages contribute to this commissural neuron population. Ventral midline crossing occurs in a manner dependent on Robo3 regulation of Robo/Slit signaling and the ventral commissure is absent in the spinal cord and hindbrain of Robo3 mutants.

PDX1 binds and represses hepatic genes to ensure robust pancreatic commitment in differentiating human embryonic stem cells.

Inactivation of the Pancreatic and Duodenal Homeobox 1 (PDX1) gene causes pancreatic agenesis, which places PDX1 high atop the regulatory network controlling development of this indispensable organ. However, little is known about the identity of PDX1 transcriptional targets. We simulated pancreatic development by differentiating human embryonic stem cells (hESCs) into early pancreatic progenitors and subjected this cell population to PDX1 chromatin immunoprecipitation sequencing (ChIP-seq).

Pancreas development in humans.

Purpose Of Review: We highlight some of the major recent advances in characterizing human pancreas development and endocrine cell differentiation.

Recent Findings: Extensive research efforts have helped to define crucial events in the mouse pancreas organogenesis. Information gained from these studies was used to develop human embryonic stem cell (hESC) differentiation protocols with the goal of generating functional glucose-responsive, insulin-producing human β-cells.

Temporal identity transition from Purkinje cell progenitors to GABAergic interneuron progenitors in the cerebellum.

In the cerebellum, all GABAergic neurons are generated from the Ptf1a-expressing ventricular zone (Ptf1a domain). However, the machinery to produce different types of GABAergic neurons remains elusive. Here we show temporal regulation of distinct GABAergic neuron progenitors in the cerebellum.

Transient cytokine treatment induces acinar cell reprogramming and regenerates functional beta cell mass in diabetic mice.

Reprogramming of pancreatic exocrine cells into cells resembling beta cells may provide a strategy for treating diabetes. Here we show that transient administration of epidermal growth factor and ciliary neurotrophic factor to adult mice with chronic hyperglycemia efficiently stimulates the conversion of terminally differentiated acinar cells to beta-like cells. Newly generated beta-like cells are epigenetically reprogrammed, functional and glucose responsive, and they reinstate normal glycemic control for up to 248 d.

Spatiotemporal patterns of multipotentiality in Ptf1a-expressing cells during pancreas organogenesis and injury-induced facultative restoration.

Pancreatic multipotent progenitor cells (MPCs) produce acinar, endocrine and duct cells during organogenesis, but their existence and location in the mature organ remain contentious. We used inducible lineage-tracing from the MPC-instructive gene Ptf1a to define systematically in mice the switch of Ptf1a(+) MPCs to unipotent proacinar competence during the secondary transition, their rapid decline during organogenesis, and absence from the mature organ. Between E11.

Lineage determinants in early endocrine development.

Pancreatic endocrine cells are produced from a dynamic epithelium in a process that, as in any developing organ, is driven by interacting programs of spatiotemporally regulated intercellular signals and autonomous gene regulatory networks. These algorithms work to push progenitors and their transitional intermediates through a series of railroad-station-like switching decisions to regulate flux along specific differentiation tracks. Extensive research on pancreas organogenesis over the last 20 years, greatly spurred by the potential to restore functional β-cell mass in diabetic patients by transplantation therapy, is advancing our knowledge of how endocrine lineage bias is established and allocation is promoted.

Context-specific α- to-β-cell reprogramming by forced Pdx1 expression.

Using single transcription factors to reprogram cells could produce important insights into the epigenetic mechanisms that direct normal differentiation, or counter inappropriate plasticity, or even provide new ways of manipulating normal ontogeny in vitro to control lineage diversification and differentiation. We enforced Pdx1 expression from the Neurogenin-3-expressing endocrine commitment point onward and found during the embryonic period a minor increased β-cell allocation with accompanying reduced α-cell numbers. More surprisingly, almost all remaining Pdx1-containing glucagon/Arx-producing cells underwent a fairly rapid conversion at postnatal stages, through glucagon-insulin double positivity, to a state indistinguishable from normal β cells, resulting in complete α-cell absence.

Xenopus Lefty requires proprotein cleavage but not N-linked glycosylation to inhibit nodal signaling.

The Nodal and Nodal-related morphogens are utilized for the specification of distinct cellular identity throughout development by activating discrete target genes in a concentration-dependant manner. Lefty is a principal extracellular antagonist involved in the spatiotemporal regulation of the Nodal morphogen gradient during mesendoderm induction. The Xenopus Lefty proprotein contains a single N-linked glycosylation motif in the mature domain and two potential cleavage sites that would be expected to produce long (Xlefty(L)) and short (Xlefty(S)) isoforms.

Ptf1a determines horizontal and amacrine cell fates during mouse retinal development.

The vertebrate neural retina comprises six classes of neurons and one class of glial cells, all derived from a population of multipotent progenitors. There is little information on the molecular mechanisms governing the specification of cell type identity from multipotent progenitors in the developing retina. We report that Ptf1a, a basic-helix-loop-helix (bHLH) transcription factor, is transiently expressed by post-mitotic precursors in the developing mouse retina.