Endocrine Progenitors Research Articles

Single-cell analyses identify distinct and intermediate states of zebrafish pancreatic islet development.

Pancreatic endocrine islets are vital for glucose homeostasis. However, the islet developmental trajectory and its regulatory network are not well understood. To define the features of these specification and differentiation processes, we isolated individual islet cells from TgBAC(neurod1:EGFP) transgenic zebrafish and analyzed islet developmental dynamics across four different embryonic stages using a single-cell RNA-seq strategy. We identified proliferative endocrine progenitors, which could be further categorized by different cell cycle phases with the G1/S subpopulation displaying a distinct differentiation potential. We identified endocrine precursors, a heterogeneous intermediate-state population consisting of lineage-primed alpha, beta and delta cells that were characterized by the expression of lineage-specific transcription factors and relatively low expression of terminally differentiation markers. The terminally differentiated alpha, beta, and delta cells displayed stage-dependent differentiation states, which were related to their functional maturation. Our data unveiled distinct states, events and molecular features during the islet developmental transition, and provided resources to comprehensively understand the lineage hierarchy of islet development at the single-cell level.

Pancreatic resident endocrine progenitors demonstrate high islet neogenic fidelity and committed homing towards diabetic mice pancreas.

Pancreatic progenitors have been explored for their profound characteristics and unique commitment to generate new functional islets in regenerative medicine. Pancreatic resident endocrine progenitors (PREPs) with mesenchymal stem cell (MSC) phenotype were purified from BALB/c mice pancreas and characterized. PREPs were differentiated into mature islet clusters in vitro by activin-A and swertisin and functionally characterized. A temporal gene and protein profiling was performed during differentiation. Furthermore, PREPs were labeled with green fluorescent protein(GFP) and transplanted intravenously into streptozotocin (STZ) diabetic mice while monitoring their homing and differentiation leading to amelioration in the diabetic condition. PREPs were positive for unique progenitor markers and transcription factors essential for endocrine pancreatic homeostasis along with having the multipotent MSC phenotype. These cells demonstrated high fidelity for islet neogenesis in minimum time (4 days) to generate mature functional islet clusters (shortest reported period for any isolated stem/progenitor). Furthermore, GFP-labeled PREPs transplanted in STZ diabetic mice migrated and localized within the injured pancreas without trapping in any other major organ and differentiated rapidly into insulin-producing cells without an external stimulus. A rapid decrease in fasting blood glucose levels toward normoglycemia along with significant increase in fasting serum insulin levels was observed, which ameliorated the diabetic condition. This study highlights the unique potential of PREPs to generate mature islets within the shortest period and their robust homing toward the damaged pancreas, which ameliorated the diabetic condition suggesting PREPs affinity toward their niche, which can be exploited and extended to other stem cell sources in diabetic therapeutics.

Glucose-Responsiveness of Pancreatic β-Like (GRP β-L) Cells Generated from Human Pluripotent Stem Cells.

The International Diabetic Federation estimated that 415 million adults currently have diabetes and 318 million adults had impaired glucose tolerance, putting them at high risk of developing diabetes in the future. In Type 1 Diabetes (T1D), the β cells are lost because of autoimmune reactions. Although islet transplantation has been a promising therapy for T1D, it is greatly limited by pancreatic donors. Here, we describe a protocol to generate glucose- responsive pancreatic β-like (GRPβ-L) cells from human-induced pluripotent stem (iPS) cells. We recapitulate in vivo pancreas development by in vitro induction of differentiating human (iPS) cells with stage-specific signaling molecules and proteins. Inhibition of Tyrosine Kinase receptor AXL, TGF-β, and Notch signaling pathways in the final stage of the five-stage protocol could efficiently generate GRPβ-L from the endocrine progenitor. Differentiation of human iPS cells through the protocol could result in functional GRPβ-L cells, which could be used in pharmaceutical and β cell biology studies. © 2018 by John Wiley & Sons, Inc.

Single-cell Transcriptomic Analyses of Mouse Pancreatic Endocrine Cells.

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, including insulin-secreting β cells, are differentiated from common endocrine progenitors during the embryonic stage. Immature endocrine cells expand via cell proliferation and mature during a long postnatal developmental period. However, the mechanisms underlying these processes are not clearly defined. Single-cell RNA-sequencing is a promising approach for the characterization of distinct cell populations and tracing cell lineage differentiation pathways. Here, we describe a method for the single-cell RNA-sequencing of isolated pancreatic β cells from embryonic, neonatal and postnatal pancreases.

Lineage dynamics of murine pancreatic development at single-cell resolution

Organogenesis requires the complex interactions of multiple cell lineages that coordinate their expansion, differentiation, and maturation over time. Here, we profile the cell types within the epithelial and mesenchymal compartments of the murine pancreas across developmental time using a combination of single-cell RNA sequencing, immunofluorescence, in situ hybridization, and genetic lineage tracing. We identify previously underappreciated cellular heterogeneity of the developing mesenchyme and reconstruct potential lineage relationships among the pancreatic mesothelium and mesenchymal cell types. Within the epithelium, we find a previously undescribed endocrine progenitor population, as well as an analogous population in both human fetal tissue and human embryonic stem cells differentiating toward a pancreatic beta cell fate. Further, we identify candidate transcriptional regulators along the differentiation trajectory of this population toward the alpha or beta cell lineages. This work establishes a roadmap of pancreatic development and demonstrates the broad utility of this approach for understanding lineage dynamics in developing organs.

Endocrine lineage biases arise in temporally distinct endocrine progenitors during pancreatic morphogenesis

Decoding the molecular composition of individual Ngn3 + endocrine progenitors (EPs) during pancreatic morphogenesis could provide insight into the mechanisms regulating hormonal cell fate. Here, we identify population markers and extensive cellular diversity including four EP subtypes reflecting EP maturation using high-resolution single-cell RNA-sequencing of the e14.5 and e16.5 mouse pancreas. While e14.5 and e16.5 EPs are constantly born and share select genes, these EPs are overall transcriptionally distinct concomitant with changes in the underlying epithelium. As a consequence, e16.5 EPs are not the same as e14.5 EPs: e16.5 EPs have a higher propensity to form beta cells. Analysis of e14.5 and e16.5 EP chromatin states reveals temporal shifts, with enrichment of beta cell motifs in accessible regions at later stages. Finally, we provide transcriptional maps outlining the route progenitors take as they make cell fate decisions, which can be applied to advance the in vitro generation of beta cells.

Development of Young Porcine Islet maturation in vitro through Helper dependent Adenovirus carrying INS-Venus

In type 1 diabetes patients, pancreatic insulin-producing β cells are absolutely deficient. It is possible to heal them by pancreas and islet transplantation. Currently the pancreas from human cadaver donor are being used for the treatments, but the lack of donor is a big problem. Several cell sources to replace these beta cells are being extensively investigated. Among them, Young Porcine Islets has become as a big expectation as a new source for the type 1 diabetes treatment. But the problem of the Young Porcine Islets are immature, so it is needed to develop the methods for the maturation in vitro. Our research has introduced the approach using the Helper dependent adenovirus (HDAdV) to insert Venus gene under the Insulin promoter (HDAdv INS-Venus), which system is available to recombiner into the genome. The Helper dependent adenovirus was previously developed to allow us carrying the long arm that to be able to recombiner efficiently. Current HDAdv INS-Venus specifically constructed to recombiner into human induced pluripotent stem (iPS) cells was previously demonstrated (1). We tested if this Adenovirus could infect also in porcine islets, and how long we could monitor. The results showed that, after 2 days of infection of 1moi, the Venus positive cells could be seen. (Fig.1). The Venus positive cells and dithizone positive cells, that is another easy indicative of the beta cells, are almost concordant. The ratio of Venus positive cells in the islets also was augmented after 3 weeks, indicating the possibility to monitor in a long time.(Fig.2)Thus, this system would enable us to develop the adequate culture methods for maturation of the cells in-vitro. We are now developing the appropriate culture methods by which the Young Porcine Islets can normalize the glucose levels in experimental induced diabetic mice.Reference:1)Yamashita-Sugahara Y, Matsumoto M, Ohtaka M, Nishimura K, Nakanishi M, Mitani K, Okazaki Y. An inhibitor of fibroblast growth factor receptor-1 (FGFR1) promotes late-stage terminal differentiation from NGN3+ pancreatic endocrine progenitors. Sci Rep. 2016 Oct 27;6:35908

Deletion of OGlcNAc Transferase in Pancreatic Progenitors Causes Partial Pancreas Agenesis and Diabetes Independent of p53 in Mice

Deletion of the only nutrient-sensor enzyme, O-GlcNAc Transferase (OGT), catalyzing O-GlcNAc addition onto target proteins in pancreatic β-cells induces diabetes through β-cell failure. We hypothesized that OGT, expressed at a very high level in β-cells, has key developmental regulatory properties. In this study, we tested the hypothesis that OGT is required for pancreas and β-cell development by deleting OGT in pancreatic (Pdx1Cre, OGTKOPanc) or endocrine (Ngn3Cre, OGTKOEndo) progenitors. We show that mice lacking OGT in pancreatic progenitors (Pdx1+, OGTKOPanc) show near pancreas agenesis and loss of β-cell mass at birth. Few mice that grow into adulthood develop overt diabetes due to functional β-cell mass failure. OGT ablation in endocrine progenitors (Ngn3+, OGTKOEndo) resulted in normal pancreas mass but reduced β-cell mass and diabetes early in life, strongly revealing the temporal and importance of OGT for β-cell development. We observed loss of Pdx1 staining at birth and on embryonic (e) day 14.5 in OGTKOPanc. Transcriptome analysis of e14.5 progenitor single cells show distinct cell clustering populations in OGTKOPanc compared to littermate controls. Upstream regulator analysis of altered genes show enhanced activation of p53, also known as TP53 or tumor protein. Next we identified p53 to be O-GlcNAc-modified in β-cells. Concomitant deletion of p53 in the OGTKOPanc background (p53,OGTKOPanc) does not rescue pancreas agenesis in OGTKOPanc newborn, and adult p53,OGTKOPanc mice develop severe hyperglycemia and diabetes. These data highlight the novel role O-GlcNAc-modifications in pancreas and β-cell development and provide a new model to characterize the developmental defects associated with pancreatic agenesis. Disclosure E. Alejandro: None. D. Baumann: None. S. Jo: None. B. Akhaphong: None. A.D. Lockridge: None. R. Mohan: None.

Pancreatic ß-Cell Specific Knockout of Grb10 Improves ß-Cell Function by Enhancing ß-Cell Differentiation and Suppressing ß-Cell Dedifferentiation

Aim: Defects in β cell differentiation are associated with type 2 diabetes in humans. Understanding the basis for β cell differentiation defects may reveal new strategies for diabetes therapy. Results: We found that Growth factor receptor binding protein 10 (Grb10) is highly expressed in mouse and human pancreas and islets and that β cell-specific knockout of Grb10 in mice increased β-cell mass and insulin content, enhanced insulin secretion from β-cells, and up-regulated mTOR and insulin signaling in islets. Pancreatic β cell-specific disruption of Grb10 expression also improved glucose tolerance in mice fed with a high fat diet and protected adult mice from STZ-induced β cell death. Pancreas-specific knockout Grb10 promoted endocrine progenitors differentiate into β cells during embryonic development. In addition, knockout Grb10 in islets alleviated STZ or high fat diet-induced β cell dedifferentiation. Conclusion: We have identified Grb10 as a key regulator of β cells differentiation/dedifferentiation and demonstrated that reducing the expression level of Grb10 has a protective effect on β-cell function. Our findings suggest a potential effective therapeutic treatment of both type 1 and type 2 diabetes. Disclosure J. Zhang: None. Z. Cai: None.

GLP-1 Controls Pancreatic Endocrine Development

Glucagon-like peptide 1 (GLP-1) has been successfully leveraged as a treatment of type 2 diabetes mellitus. Its beneficial effects on β-cell growth and function are documented in the adult rodents but its role during pancreatic organogenesis remains unexplored. GLP-1 has numerous targets in vivo and has been shown to regulate key signaling pathways in β-cells. In the mature islets, GLP-1 modulates the MAPK and Akt signaling pathways, controls glucose sensing and responsiveness and increases Pdx-1 levels. All these processes are also known to be instrumental in the regulation of the proper growth, differentiation and maturation of the early endocrine progenitors. A few studies indirectly implied that GLP-1 could also have some impact on pancreatic organogenesis, promoting endocrine development in in vitro models. However, adult GLP-1 receptor (GLP-1R) knock out mice only display mild metabolic impairments mostly triggered by exposure to high-fat diet, but the phenotype of these animals had not been studied during early development. Using our total body knockout of the GLP-1 receptor, we found that total size of the pancreas of the newborn knocked-out animals appears to be reduced at birth and the β-cell mass is diminished by 89%. These results support that GLP-1R signaling is crucial for normal pancreatic development but that catch up growth can takes place between birth and adulthood to compensate for reduced GLP-1R signaling. These data illustrate that in addition to its insulinotropic effects in mature islets, GLP-1 signaling plays a central role during pancreatic development and the acquisition of a normal β-cell mass. Disclosure C.M.H. Cras-Méneur: None. R.J. Seeley: Research Support; Self; Novo Nordisk Inc., Novo Nordisk Inc., Ethicon US, LLC.. Consultant; Self; Janssen Pharmaceuticals, Inc.. Research Support; Self; Zafgen, MedImmune. Consultant; Self; Kallyope, Scohia.

Secretagogin protects Pdx1 from proteasomal degradation to control a transcriptional program required for β cell specification

ObjectiveSpecification of endocrine cell lineages in the developing pancreas relies on extrinsic signals from non-pancreatic tissues, which initiate a cell-autonomous sequence of transcription factor activation and repression switches. The steps in this pathway share reliance on activity-dependent Ca2+ signals. However, the mechanisms by which phasic Ca2+ surges become converted into a dynamic, cell-state-specific and physiologically meaningful code made up by transcription factors constellations remain essentially unknown. MethodsWe used high-resolution histochemistry to explore the coincident expression of secretagogin and transcription factors driving β cell differentiation. Secretagogin promoter activity was tested in response to genetically manipulating Pax6 and Pax4 expression. Secretagogin null mice were produced with their pancreatic islets morphologically and functionally characterized during fetal development. A proteomic approach was utilized to identify the Ca2+-dependent interaction of secretagogin with subunits of the 26S proteasome and verified in vitro by focusing on Pdx1 retention. ResultsHere, we show that secretagogin, a Ca2+ sensor protein that controls α and β cell turnover in adult, is in fact expressed in endocrine pancreas from the inception of lineage segregation in a Pax4-and Pax6-dependent fashion. By genetically and pharmacologically manipulating secretagogin expression and interactome engagement in vitro, we find secretagogin to gate excitation-driven Ca2+ signals for β cell differentiation and insulin production. Accordingly, secretagogin−/− fetuses retain a non-committed pool of endocrine progenitors that co-express both insulin and glucagon. We identify the Ca2+-dependent interaction of secretagogin with subunits of the 26S proteasome complex to prevent Pdx1 degradation through proteasome inactivation. This coincides with retained Nkx6.1, Pax4 and insulin transcription in prospective β cells. ConclusionsIn sum, secretagogin scales the temporal availability of a Ca2+-dependent transcription factor network to define β cell identity.

Differentiation of human pluripotent stem cells into two distinct NKX6.1 populations of pancreatic progenitors

BackgroundThe expression of a specific combination of transcription factors (TFs) in the multipotent progenitor cells (MPCs) is critical for determining pancreatic cell fate. NKX6.1 expression in PDX1+ MPCs is required for functional β cell generation. We have recently demonstrated the generation of a novel population of human pluripotent stem cell (hPSC)-derived MPCs that exclusively express NKX6.1, independently of PDX1 (PDX1−/NKX6.1+). Therefore, the aim of this study was to characterize this novel population to elucidate its role in pancreatic development.MethodsThe hPSCs were exposed to two differentiation protocols to generate MPCs that were analyzed using different techniques.ResultsBased on the expression of PDX1 and NKX6.1, we generated three different populations of MPCs, two of them were NKX6.1+. One of these NKX6.1 populations coexpressed PDX1 (PDX1+/NKX6.1+) which is known to mature into functional β cells, and an additional novel population did not express PDX1 (PDX1−/NKX6.1+) with an undefined role in pancreatic cell fate. This novel population was enriched using our recently established protocol, allowing their reorganization in three-dimensional (3D) structures. Since NKX6.1 induction in MPCs can direct them to endocrine and/or ductal cells in humans, we examined the coexpression of endocrine and ductal markers. We found that the expression of the pancreatic endocrine progenitor markers chromogranin A (CHGA) and neurogenin 3 (NGN3) was not detected in the NKX6.1+ 3D structures, while few structures were positive for NKX2.2, another endocrine progenitor marker, thereby shedding light on the origin of this novel population and its role in pancreatic endocrine development. Furthermore, SOX9 was highly expressed in the 3D structures, but cytokeratin 19, a main ductal marker, was not detected in these structures.ConclusionsThese data support the existence of two independent NKX6.1+ MPC populations during human pancreatic development and the novel PDX1−/NKX6.1+ population may be involved in a unique trajectory to generate β cells in humans.

SIRT6-mediated transcriptional suppression of Txnip is critical for pancreatic beta cell function and survival in mice.

Better understanding of how genetic and epigenetic components control beta cell differentiation and function is key to the discovery of novel therapeutic approaches to prevent beta cell dysfunction and failure in the progression of type 2 diabetes. Our goal was to elucidate the role of histone deacetylase sirtuin 6 (SIRT6) in beta cell development and homeostasis. Sirt6 endocrine progenitor cell conditional knockout and beta cell-specific knockout mice were generated using the Cre-loxP system. Mice were assayed for islet morphology, glucose tolerance, glucose-stimulated insulin secretion and susceptibility to streptozotocin. Transcriptional regulatory functions of SIRT6 in primary islets were evaluated by RNA-Seq analysis. Reverse transcription-quantitative (RT-q)PCR and immunoblot were used to verify and investigate the gene expression changes. Chromatin occupancies of SIRT6, H3K9Ac, H3K56Ac and active RNA polymerase II were evaluated by chromatin immunoprecipitation. Deletion of Sirt6 in pancreatic endocrine progenitor cells did not affect endocrine morphology, beta cell mass or insulin production but did result in glucose intolerance and defective glucose-stimulated insulin secretion in mice. Conditional deletion of Sirt6 in adult beta cells reproduced the insulin secretion defect. Loss of Sirt6 resulted in aberrant upregulation of thioredoxin-interacting protein (TXNIP) in beta cells. SIRT6 deficiency led to increased acetylation of histone H3 lysine residue at 9 (H3K9Ac), acetylation of histone H3 lysine residue at 56 (H3K56Ac) and active RNA polymerase II at the promoter region of Txnip. SIRT6-deficient beta cells exhibited a time-dependent increase in H3K9Ac, H3K56Ac and TXNIP levels. Finally, beta cell-specific SIRT6-deficient mice showed increased sensitivity to streptozotocin. Our results reveal that SIRT6 suppresses Txnip expression in beta cells via deacetylation of histone H3 and plays a critical role in maintaining beta cell function and viability. Sequence data have been deposited in the National Institutes of Health (NIH) Gene Expression Omnibus (GEO) with the accession code GSE104161.

Understanding human fetal pancreas development using subpopulation sorting, RNA sequencing and single-cell profiling.

To decipher the populations of cells present in the human fetal pancreas and their lineage relationships, we developed strategies to isolate pancreatic progenitors, endocrine progenitors and endocrine cells. Transcriptome analysis of the individual populations revealed a large degree of conservation among vertebrates in the drivers of gene expression changes that occur at different steps of differentiation, although notably, sometimes, different members of the same gene family are expressed. The transcriptome analysis establishes a resource to identify novel genes and pathways involved in human pancreas development. Single-cell profiling further captured intermediate stages of differentiation and enabled us to decipher the sequence of transcriptional events occurring during human endocrine differentiation. Furthermore, we evaluate how well individual pancreatic cells derived in vitro from human pluripotent stem cells mirror the natural process occurring in human fetuses. This comparison uncovers a few differences at the progenitor steps, a convergence at the steps of endocrine induction, and the current inability to fully resolve endocrine cell subtypes in vitro.

GRP94 Is an Essential Regulator of Pancreatic β-Cell Development, Mass, and Function in Male Mice.

Deficiencies in pancreatic β-cell mass contribute to both type 1 and type 2 diabetes. We investigated the role of the glucose-regulated protein (GRP) 94, an endoplasmic reticulum protein abundantly expressed in the pancreatic acini and islets, in β-cell development, survival, and function. We used a conditional knockout (KO) mouse in which the GRP94 gene, Hsp90b1, was specifically deleted in pancreatic and duodenal homeobox 1 (Pdx1)-expressing cells. These Hsp90b1 flox/flox;Pdx1Cre KO mice exhibited pancreatic hypoplasia at embryonic day (E) 16.5 to E18.5 and had significantly reduced β-cell mass at 4 weeks after birth. Further mechanistic studies showed that deletion of GRP94 reduced β-cell proliferation with increased cell apoptosis in both Pdx1+ endocrine progenitor cells and differentiated β cells. Although Hsp90b1 flox/flox;Pdx1Cre KO mice remained euglycemic at 8 weeks of age, they exhibited impaired glucose tolerance. In aggregate, these findings indicate that GRP94 is an essential regulator of pancreatic β-cell development, mass, and function.

Erratum: EGFR signalling controls cellular fate and pancreatic organogenesis by regulating apicobasal polarity.

This corrects the article DOI: 10.1038/ncb3628.

Afadin and RhoA control pancreatic endocrine mass via lumen morphogenesis.

Proper lumen morphogenesis during pancreas development is critical to endocrine and exocrine cell fate. Recent studies showed that a central network of lumens (termed core), but not the surrounding terminal branches (termed periphery), produces most islet endocrine cells. To date, it remains unclear how pancreatic lumens form and remodel and which aspects of lumen morphogenesis influence cell fate. Importantly, models testing the function of the central lumen network as an endocrine niche are lacking. Here, we identify mechanisms underlying lumen formation and remodeling and show that central lumen network morphogenesis impacts pancreatic endocrine mass. We show that loss of the scaffolding protein Afadin disrupts de novo lumenogenesis and lumen continuity in the tip epithelium. Codepletion of the actomyosin regulator RhoA and Afadin results in defects in the central lumens and arrests lumen remodeling. This arrest leads to prolonged perdurance of the central lumen network over developmental time and expansion of the endocrine progenitor population and, eventually, endocrine mass. Our study uncovers essential roles of Afadin and RhoA in pancreatic central lumen morphogenesis, which subsequently determines endocrine cell mass.

EGFR signalling controls cellular fate and pancreatic organogenesis by regulating apicobasal polarity.

Apicobasal polarity is known to affect epithelial morphogenesis and cell differentiation, but it remains unknown how these processes are mechanistically orchestrated. We find that ligand-specific EGFR signalling via PI(3)K and Rac1 autonomously modulates apicobasal polarity to enforce the sequential control of morphogenesis and cell differentiation. Initially, EGF controls pancreatic tubulogenesis by negatively regulating apical polarity induction. Subsequently, betacellulin, working via inhibition of atypical protein kinase C (aPKC), causes apical domain constriction within neurogenin3+ endocrine progenitors, which results in reduced Notch signalling, increased neurogenin3 expression, and β-cell differentiation. Notably, the ligand-specific EGFR output is not driven at the ligand level, but seems to have evolved in response to stage-specific epithelial influences. The EGFR-mediated control of β-cell differentiation via apical polarity is also conserved in human neurogenin3+ cells. We provide insight into how ligand-specific EGFR signalling coordinates epithelial morphogenesis and cell differentiation via apical polarity dynamics.

Single-Cell Gene Expression Analysis of a Human ESC Model of Pancreatic Endocrine Development Reveals Different Paths to β-Cell Differentiation.

SummaryThe production of insulin-producing β cells from human embryonic stem cells (hESCs) in vitro represents a promising strategy for a cell-based therapy for type 1 diabetes mellitus. To explore the cellular heterogeneity and temporal progression of endocrine progenitors and their progeny, we performed single-cell qPCR on more than 500 cells across several stages of in vitro differentiation of hESCs and compared them with human islets. We reveal distinct subpopulations along the endocrine differentiation path and an early lineage bifurcation toward either polyhormonal cells or β-like cells. We uncover several similarities and differences with mouse development and reveal that cells can take multiple paths to the same differentiation state, a principle that could be relevant to other systems. Notably, activation of the key β-cell transcription factor NKX6.1 can be initiated before or after endocrine commitment. The single-cell temporal resolution we provide can be used to improve the production of functional β cells.

Late-stage differentiation of embryonic pancreatic \u03b2-cells requires Jarid2

Jarid2 is a component of the Polycomb Repressor complex 2 (PRC2), which is responsible for genome-wide H3K27me3 deposition, in embryonic stem cells. However, Jarid2 has also been shown to exert pleiotropic PRC2-independent actions during embryogenesis. Here, we have investigated the role of Jarid2 during pancreas development. Conditional ablation of Jarid2 in pancreatic progenitors results in reduced endocrine cell area at birth due to impaired endocrine cell differentiation and reduced prenatal proliferation. Inactivation of Jarid2 in endocrine progenitors demonstrates that Jarid2 functions after endocrine specification. Furthermore, genome-wide expression analysis reveals that Jarid2 is required for the complete activation of the insulin-producing β-cell differentiation program. Jarid2-deficient pancreases exhibit impaired deposition of RNAPII-Ser5P, the initiating form of RNAPII, but no changes in H3K27me3, at the promoters of affected endocrine genes. Thus, our study identifies Jarid2 as a fine-tuner of gene expression during late stages of pancreatic endocrine cell development. These findings are relevant for generation of transplantable stem cell-derived β-cells.