RNA-seq of ISL1 overexpression during islet differentiation.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE313800 | GEO | 2025/12/23
REPOSITORIES: GEO
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Project description:Visceral fat (VF) and subcutaneous fat (SF) are developmentally different tissues with different gene expression. Islet-1 (ISL1), a LIM-homeobox transcription factor with important developmental and regulatory function in islet, neural, and cardiac tissue, is virtually absent in SF but substantially expressed in the stromovascular [preadipocyte containing] fraction of VF; expression correlates negatively with adiposity in rodents and man. ISL1 expression is transiently increased in 3T3-L1 preadipocytes during early differentiation, suggesting a functional role. To examine the role of ISL1 in adipogenesis, we tested whether retroviral overexpression of ISL1 in 3T3-L1 preadipocytes affected their ability to differentiate into mature adipocytes. Terminal differentiation was assessed by Oil Red O [lipid droplet] staining and by immunoblot detection of adipocyte marker proteins, including aP2 and GLUT4. ISL1 significantly inhibited lipid droplet formation, reduced lipid accumulation (about 80% inhibition, p<0.05), and substantially inhibited aP2 and GLUT4 expression. ISL1 did not inhibit expression of C/EBPb and C/EBPd after induction of differentiation, but reduced PPARg and C/EBPa by >50% at both mRNA and protein level. In addition, the PPARg agonist, rosiglitazone, substantially rescued ISL1 inhibited adipogenesis in the absence of exogenous PPARg, and fully rescued in the presence of exogenous PPARg. In summary, ISL1 overexpression inhibited fat droplet formation, lipid accumulation, and adipocyte-specific gene expression; there was accompanying inhibition of C/EBPa, PPARg and downstream gene expression. We conclude that ISL1 overexpression inhibited adipocyte differentiation by inhibition of PPARg regulated gene expression. As abdominal obesity strongly correlates with insulin resistance, and cardiovascular risk, ISL1 up-regulation may impact abdominal obesity and its concomitant metabolic derangements. Total cellular RNA was isolated from 3T3-L1 cells expressing Flag-ISL1 or not at 48 h following treatment with differentiation cocktail. Individual RNA from biological triplicates was used for microarray analysis.
2012-09-05 | E-GEOD-40565 | biostudies-arrayexpress
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:Loss of pancreatic beta cells is the central feature of all forms of diabetes. Current therapies fail to halt the declined beta cell mass. Thus, strategies to preserve beta cells are imperatively needed. In this study, we identified paired box 6 (PAX6) as a critical regulator of beta cell survival. Under diabetic conditions, the human beta cell line EndoC-bH1, db/db mouse and human islets displayed dampened insulin and incretin signalings and reduced beta cell survival, which were alleviated by PAX6 overexpression. Adeno-associated virus (AAV)-mediated PAX6 overexpression in beta cells of streptozotocin-induced diabetic mice and db/db mice led to a sustained maintenance of glucose homeostasis. AAV-PAX6 transduction in human islets reduced islet graft loss and improved glycemic control after transplantation into immunodeficient diabetic mice. Our study highlights a previously unappreciated role for PAX6 in beta cell survival and raises the possibility that ex vivo PAX6 gene transfer into islets prior to transplantation might enhance islet graft function and transplantation outcome.
2023-10-13 | GSE242338 | GEO
Project description:The LIM-homeobox transcription factor islet-1 (ISL1) has been proposed as a marker of cardiovascular progenitor cells. This study investigated whether forced expression of ISL1 in human mesenchymal stem cells (hMSCs) improves myocardial infarction (MI) treatment outcomes. The lentiviral vector EF1α-ISL1 was constructed using the Multisite Gateway System, and used to transduce hMSCs.
2018-01-01 | GSE107923 | GEO
Project description:Pancreatic neuroendocrine tumors (PanNET) were classified into grades (G) 1-3 by the World Health Organization in 2017, but the precise mechanisms of PanNET initiation and progression have remained unclear. In this study, we used a genetically engineered mouse model to investigate the mechanisms of PanNET formation. Although pancreas-specific deletion of the Rb gene (Pdx1-Cre;Rbf/f) in mice did not affect pancreatic exocrine cells, the α-cell/β-cell ratio of islet cells was decreased at 8 months of age. During long-term observation (18-20 months), mice formed well-differentiated PanNET with a Ki67-labeling index of 2.7%. In contrast, pancreas-specific induction of a p53 mutation (Pdx1-Cre;Trp53R172H) had no effect on pancreatic exocrine and endocrine tissues, but simultaneous induction of a p53 mutation with Rb gene deletion (Pdx1-Cre;Trp53R172H;Rb f/f) resulted in the formation of aggressive PanNET with a Ki67-labeling index of 24.7% over the short-term (4 months). In Pdx1-Cre;Trp53R172H;Rb f/f mice, mRNA expression of Pten and Tsc2, negative regulators of the mTOR pathway, significantly decreased in the islet cells, and activation of the mTOR pathway was confirmed in subsequently formed PanNET. Thus, by manipulating Rb and p53 genes, we established a multistep progression model from dysplastic islet to indolent PanNET and aggressive metastatic PanNET in mice. These observations suggest that Rb and p53 have distinct roles in the development of PanNET.
2020-06-17 | GSE152582 | GEO
Project description:Cpt1a WT vs Pdx1-cre Islet RNA
| PRJNA1091693 | ENA
Project description:We anticipated that the identification of cis-regulatory regions active in pancreatic islets would help increase our understanding of islet biology and the pathology of diabetes. Towards this end we used histone H3 lysine 4 monomethylation-based nucleosome predictions genome-wide, in conjunction with binding data for PDX1, FOXA2, MAFA, and NEUROD1, to identify 3,654 putative enhancers that are H3K4me1-enriched uniquely in islets as compared to 14 other tissue or cell-types. We show that these islet-specific enhancers are associated with genes with significantly higher islet specificity than genes associated with non-specific enhancers. Further, islet-specific enhancers were not enriched for typical active or repressive histone methylations in embryonic stem cells and liver, suggesting they are formed by de novo histone methylation during pancreas development. We also identify a subset of enhancers bivalently marked by both H3K4me1 and H3K27me3 in adult pancreatic islets. Further, we show that islet-specific enhancers triple- or quadruple- bound by PDX1, MAFA, NEUROD1 and/or FOXA2 are associated with genes with particularly high islet-specificity, and that these loci are enriched in regions with functional activity in islet cell types. Finally, we demonstrate that cytokines reduce H3K4me1 enrichment levels at selected triple- or quadruple-bound islet-specific enhancers, suggesting that epigenetic changes may contribute to cytokine-induced b-cell dysfunction. In conjunction with data from Hoffman et al Genome Research 2010, an analysis of histone modifications and transcription factor binding sites to identify enhancer regions
2011-06-30 | E-GEOD-30298 | biostudies-arrayexpress
Project description:Remarkable advancements in protocol development have been achieved to manufacture insulin-secreting islets from human pluripotent stem cells. Distinct from current approaches, we devised a tunable strategy to generate islet spheroids enriched for major islet cell types by incorporating PDX1+ cell budding morphogenesis into the differentiation process of staged transcriptional programming. In this process that appears to mimic normal islet morphogenesis, the differentiating islet spheroids self-organize with endocrine cells that are intermingled or arranged in a core-mantle architecture, accompanied with functional heterogeneity. Through in vitro modelling of human pancreas development, we illustrate the importance of PDX1 in eliciting cell budding morphogenesis, and the requirement for EphB3/4 signaling. We show how RFX6 deficiency affects pancreatic patterning and uncover an expected role of RFX6 in early pancreas morphology. The tunable differentiation system and stem cell-derived islet models described in this work may facilitate addressing fundamental questions in islet biology and probing human pancreas diseases.
2024-05-15 | GSE249020 | GEO
Project description:Congenital heart defects (CHDs) are frequently observed in the most common form of Cornelia de Lange Syndrome (CdLS), which is caused by haploinsufficiency for NIPBL, a gene involved in chromatin looping and cis-regulatory control of gene expression. Here, we surveyed cardiac defects in mice made Nipbl-haploinsufficient in the second heart field using two Cre drivers: Mef2c-Cre and Isl1-Cre. Only Isl1-Cre-driven Nipbl-haploinsufficiency resulted in CHDs – a finding we traced to the additional contribution of Isl1-haploinsufficiency caused by the Isl1-Cre allele. To test whether combined reduction of Nipbl and Isl1 cause CHDs, we made mice globally haploinsufficient for both genes. Indeed, Nipbl+/-; Isl1+/- mice exhibited a substantially higher frequency and severity of CHDs than mice haploinsufficient for either gene alone. As a member of the LIM-homeodomain transcription factor family, Isl1 is involved in chromatin looping and enhancer-promoter communication via a mechanism distinct from that of Nipbl. Nevertheless, when we performed RNA sequencing on E10.5 hearts from wildtype, Nipbl+/-, Isl1+/-, and Nipbl+/-; Isl1+/- embryos, we observed that combined haploinsufficiency resulted in largely additive gene expression changes, including dysregulation of known cardiac regulators (Irx4, Tbx1, Foxo6, Heyl, Bnc1, Sox17) and novel candidates (Gbx1, Csdc2, Myrf, Pou6f1, Zfp579, ad Zfp763). A subset of additive changes arose from opposing regulatory influences in single mutants that restored gene expression to WT levels in Nipbl⁺/⁻; Isl1⁺/⁻ hearts. For example, Hoxc4, Pitx2, Isl1 itself, and Pax6 (a known target of Isl1), were upregulated in Nipbl+/- hearts, downregulated in Isl1+/- hearts, but expressed at WT levels in Nipbl⁺/⁻; Isl1⁺/⁻ hearts. Since loss of Isl1 upregulation from Nipbl+/- to Nipbl+/-; Isl1+/- hearts coincided with a marked increase in CHDs, we propose that Isl1 upregulation compensates for the loss of cis-regulatory interactions due to Nipbl-haploinsufficiency, and protects hearts from severe CHD risk. Supporting this model, other LIM-homeodomain transcription factors (Lhx2, Lhx3, Lhx9) were also upregulated in Nipbl+/- hearts, with Lhx3 and Lhx9 showing even greater upregulation in Nipbl+/-; Isl1+/- hearts. Despite this, CHDs resulting from the combined loss of Nipbl and Isl1 were particularly severe. These findings suggest that heart development is exquisitely sensitive to small change in gene expression, leading to synergistic phenotypic interactions when relatively modest gene expression changes are combined.
2025-05-19 | GSE278563 | GEO