The Islet-1 Interaction Partner Rnf20 Regulates Glucose Homeostasis and Pancreatic β-cell Identity.
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ABSTRACT:
PROVIDER: PRJNA1181900 | ENA |
REPOSITORIES: ENA
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Project description:Diabetes is characterized by a loss of functional β-cell mass, thereby identifying factors involved in establishing and preserving β-cell identity and function is critical for future therapies aiming to combat rising diabetes incidence. While transcription factors are crucial β-cell regulators, knowledge of the interacting co-regulators facilitating gene expression is limited. Previously, we demonstrated that the Islet-1 (Isl1) transcription factor forms complexes with histone ubiquitin ligases Rnf20 and Rnf40 to regulate β-cell gene expression and insulin secretion in vitro. Here, we investigated whether Rnf20-mediated complexes are required for β-cell function in adult islets using an adult-inducible β-cell-enriched Rnf20 knockout mouse model, termed Rnf20Δβ-cell . Tamoxifen induction of Rnf20 recombination prompted a robust loss of histone 2B monoubiquitination (H2Bub1) in b-cells and imparted severe hyperglycemia and glucose intolerance, reduced plasma insulin levels following a glucose challenge, and an overall reduction in insulin content. Expression of mRNAs and proteins involved in glucose stimulated insulin secretion (GSIS) and β-cell identity were also dysregulated in Rnf20Δβ-cell mice. Furthermore, comparative loss of either Rnf20 or Isl1 yielded a similar differential expression of numerous b-cell factors, supporting that Isl1::Rnf20 complexes and histone H2B mono-ubiquitination are critical regulators of cellular identity and function.
2025-08-04 | GSE281063 | GEO
Project description:Generation of mature cells with stable functional identities is crucial for developing cell-based replacement therapies. Current global efforts to produce insulin-secreting beta-like cells to treat diabetes are hampered by the lack of tools to reliably assess cellular identity. We conducted a thorough single-cell transcriptomics meta-analysis to generate robust genesets defining the identity of human adult alpha-, beta-, gamma- and delta-cells. After extensive validation, we showed the efficacy of the novel genesets to define changes in islet cell identity, whether during embryonic development or in different experimental setups aimed at developing new functional glucose-responsive insulin-secreting cells, such as through pluripotent stem-cell differentiation or islet cell reprogramming protocols. Finally, we evaluated whether the perturbed metabolic conditions typical of diabetes influence islet cell identity. We observed that alpha-cells from diabetic donors exhibit an altered phenotype. In conclusion, these novel genesets represent valuable tools that robustly benchmark gain and loss in islet cell identity traits.
2021-06-26 | GSE150724 | GEO
Project description:Objective: Transcriptional complex activity drives the development and function of pancreatic islet cells to allow for proper glucose regulation. Our prior work highlighted that the LIM-homeodomain transcription factor (TF), Islet-1 (Isl1), and its interacting co-regulator, Ldb1, are vital effectors of developing and adult β-cells. We further found that a member of the Single Stranded DNA-Binding Protein (SSBP) co-regulator family, SSBP3, interacts with Isl1 and Ldb1 in β-cells and primary islets (mouse and human) to impact β-cell target genes MafA and Glp1R. Members of the SSBP family stabilize TF complexes by binding directly to Ldb1 and protecting the complex from ubiquitin-mediated turnover. In this study, we hypothesized that SSBP3 would have critical roles in pancreatic islet cell development and function in vivo, similar to the Isl1::Ldb1 complex. Methods: We first generated a novel SSBP3 LoxP allele mouse line, where Cre-mediated recombination imparts a predicted early protein termination. We bred this mouse to constitutive Cre lines (Pdx1- and Pax6-driven) to recombine of SSBP3 in the developing pancreas and islet (SSBP3DeltaPanc and SSBP3DeltaIslet), respectively. We assessed glucose tolerance and used immunofluorescence to detect changes in islet cell abundance and markers of β-cell identity and function. Using an inducible Cre system we also deleted SSBP3 in the adult β-cell, a model termed SSBP3Deltaβ-cell. We measured glucose tolerance as well as glucose-stimulated insulin secretion (GSIS), both in vivo and in isolated islets in vitro. Using islets from control and SSBP3Deltaβ-cell we conducted RNA-Seq and compared our results to published datasets for similar β-cell specific Ldb1 and Isl1 knockouts to identify commonly regulated target genes. Results: SSBP3DeltaPanc and SSBP3DeltaIslet neonates present with hyperglycemia. SSBP3DeltaIslet mice are glucose intolerant by P21 and exhibit a reduction of β-cell maturity markers MafA, Pdx1, and UCN3. We observe disruptions in islet cell architecture with an increase in glucagon+ α-cells and ghrelin+ ε-cells at P10. Inducible loss of β-cell SSBP3 in SSBP3Deltaβ-cell causes hyperglycemia, glucose intolerance, and reduced GSIS. Transcriptomic analysis of 14-week SSBP3Deltaβ-cell islets revealed a decrease in β-cell function gene expression (Ins, MafA, Ucn3), increased stress and dedifferentiation markers (Neurogenin-3, Aldh1a3, Gastrin), and shared differentially expressed genes between SSBP3, Ldb1, and Isl1 in adult β-cells. Conclusions: SSBP3 drives proper islet development and identity, where its loss causes altered islet-cell abundance and glucose regulatory function. β-cell SSBP3 is required for GSIS and glucose homeostasis, at least partially through shared regulation of Ldb1 and Isl1 target genes.
2023-08-16 | GSE232750 | GEO
Project description:Generation of Human Islet Cell-Type-Specific Identity Genesets
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Project description:Type 2 diabetes (T2D) is associated with compromised identity of insulin-producing pancreatic islet beta (β) cells, characterized by inappropriate production of other islet cell-enriched hormones. Here we examined how hormone misexpression was influenced by the MAFA and MAFB transcription factors, closely related proteins that maintain islet cell function. Mice specifically lacking MafA in β cells demonstrated broad, population-wide changes in hormone gene expression with an overall gene signature closely resembling islet gastrin (Gast)-positive cells generated under conditions of chronic hyperglycemia and obesity. A human b cell line deficient in MAFB, but not one lacking MAFA, also produced a gastrin (GAST)-positive gene expression pattern. In addition, GAST was detected in human T2D β cells with low levels of MAFB. Moreover, evidence is provided that human MAFB can directly repress GAST gene transcription. These results support a novel, species-specific role for MafA and MAFB in maintaining adult mouse and human β cell identity, respectively, by repressing expression of Gast/GAST and other non-b cell hormones.
2023-05-01 | GSE230728 | GEO
Project description:Experiments were performed to investigate the BAT proteome of RNF20 WT and heterozygous-null mice.
2024-02-05 | PXD048556 | Pride
Project description:The mechanisms restricting regeneration and maintaining cell identity upon injury are poorly characterized in higher vertebrates. Upon β-cell loss, 1-2% of the glucagon-producing α-cells spontaneously engage insulin production in mice. Here we explore the mechanisms of this plasticity. We show that the adaptive α-cell identity changes are constrained by intra-islet Insulin- and Smoothened-mediated signaling, among others. Combining β-cell loss, or insulin signaling inhibition, with Smoothened inactivation in α- or δ-cells, stimulates insulin production in more α-cells. These findings suggest that removing constitutive “brake signals” is crucial for neutralizing the refractoriness to adaptive cell-fate changes. It appears that cell identity maintenance is an active process mediated by repressive signals curbing an intrinsic trend of differentiated cells to change.
2018-06-18 | GSE109285 | GEO
Project description:WAC is a known positive regulator of (macro)autophagy. WAC also forms a complex with RNF20/RNF40 to promote H2B monoubiquitination and hence to affect transcriptional regulation. This study addresses whether the WAC/RNF20/RNF40 complex regulates autophagy through effects on gene expression. WAC, RNF20 and RNF40 were knocked-down using pools of siRNAs in HEK293A cells. Each knockdown was in triplicate and the control was RISCfree siRNA. mRNA expression profiles were investigated using an Illumina HT12v4 Bead Array.
2015-12-17 | E-GEOD-66475 | biostudies-arrayexpress
Project description:MLL-fusions are potent oncogenes that initiate aggressive forms of acute leukemia. As aberrant transcriptional regulators, MLL-fusion proteins alter gene expression in hematopoietic cells through interactions with the histone H3 lysine 79 (H3K79) methyltransferase DOT1L. Notably, interference with MLL-fusion cofactors like DOT1L is an emerging therapeutic strategy in this disease. Here we identify the histone H2B E3 ubiquitin ligase RNF20 as an additional requirement for MLL-fusion-mediated leukemogenesis. Suppressing the expression of Rnf20 in diverse models of MLL-rearranged leukemia leads to inhibition of cell proliferation; under tissue culture conditions as well as in vivo. Rnf20 knockdown leads to reduced expression of MLL-fusion target genes, including Hoxa9 and Meis1; effects that resemble Dot1l-inhibition. Using ChIP-seq, we found that H2B ubiquitination (H2Bub) is enriched in the body of MLL-fusion target genes, correlating with sites of H3K79 methylation and transcription elongation. Furthermore, we found that Rnf20 is required to maintain local levels of H3K79 di-methylation by Dot1l at Hoxa9 and Meis1. These findings support a model whereby co-transcriptional recruitment of Rnf20 at MLL-fusion target genes leads to amplification of Dot1l-mediated H3K79 methylation, thereby rendering leukemia cells dependent on Rnf20 to maintain their oncogenic transcriptional program. Examination of gene expression profiles upon RNF20 RNAi in MLL-AF9 acute myeloid leukemia cells
2013-02-19 | E-GEOD-43725 | biostudies-arrayexpress
Project description:Pancreatic Islet-Autonomous Signals Modulate Identity Changes of Glucagon+ α-Cells
| PRJNA430357 | ENA