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Toren E, Kepple JD, Coutinho KV, Poole SO, Deeba IM, Pierre TH, Liu Y, Bethea MM, Hunter CS. The SSBP3 co-regulator is required for glucose homeostasis, pancreatic islet architecture, and beta-cell identity. Mol Metab 2023; 76:101785. [PMID: 37536498 PMCID: PMC10448474 DOI: 10.1016/j.molmet.2023.101785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023] Open
Abstract
OBJECTIVE Transcriptional complex activity drives the development and function of pancreatic islet cells to allow for proper glucose regulation. Prior studies from our lab and others 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 in vitro. 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 has critical roles in pancreatic islet cell function in vivo, similar to the Isl1::Ldb1 complex. METHODS We first developed a novel SSBP3 LoxP allele mouse line, where Cre-mediated recombination imparts a predicted early protein termination. We bred this mouse with constitutive Cre lines (Pdx1- and Pax6-driven) to recombine SSBP3 in the developing pancreas and islet (SSBP3ΔPanc and SSBP3ΔIslet), 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 SSBP3Δβ-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 SSBP3Δβ-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 SSBP3ΔPanc and SSBP3ΔIslet neonates present with hyperglycemia. SSBP3ΔIslet 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 SSBP3Δβ-cell causes hyperglycemia, glucose intolerance, and reduced GSIS. Transcriptomic analysis of 14-week-old SSBP3Δβ-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 identity and function, where its loss causes altered islet-cell abundance and glucose homeostasis. β-Cell SSBP3 is required for GSIS and glucose homeostasis, at least partially through shared regulation of Ldb1 and Isl1 target genes.
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Affiliation(s)
- Eliana Toren
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jessica D Kepple
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kristen V Coutinho
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Samuel O Poole
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Iztiba M Deeba
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Tanya H Pierre
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Yanping Liu
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Maigen M Bethea
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chad S Hunter
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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2
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Abstract
Excess nutrients and proinflammatory cytokines impart stresses on pancreatic islet β-cells that, if unchecked, can lead to cellular dysfunction and/or death. Among these stress-induced effects is loss of key β-cell transcriptional regulator mRNA and protein levels required for β-cell function. Previously, our lab and others reported that LIM-domain complexes comprised the LDB1 transcriptional co-regulator and Islet-1 (ISL1) transcription factor are required for islet β-cell development, maturation, and function. The LDB1:ISL1 complex directly occupies and regulates key β-cell genes, including MafA, Pdx1, and Slc2a2, to maintain β-cell identity and function. Given the importance of LDB1:ISL1 complexes, we hypothesized that LDB1 and/or ISL1 levels, like other transcriptional regulators, are sensitive to β-cell nutrient and cytokine stresses, likely contributing to β-cell (dys)function under various stimuli. We tested this by treating β-cell lines or primary mouse islets with elevating glucose concentrations, palmitate, or a cytokine cocktail of IL-1β, TNFα, and IFNγ. We indeed observed that LDB1 mRNA and/or protein levels were reduced upon palmitate and cytokine (cocktail or singly) incubation. Conversely, acute high glucose treatment of β-cells did not impair LDB1 or ISL1 levels, but increased LDB1:ISL1 interactions. These observations suggest that LDB1:ISL1 complex formation is sensitive to β-cell stresses and that targeting and/or stabilizing this complex may rescue lost β-cell gene expression to preserve cellular function.
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Affiliation(s)
- Yanping Liu
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism University of Alabama at Birmingham, Birmingham, AL, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jessica D. Kepple
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism University of Alabama at Birmingham, Birmingham, AL, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Anath Shalev
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism University of Alabama at Birmingham, Birmingham, AL, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chad S. Hunter
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism University of Alabama at Birmingham, Birmingham, AL, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
- CONTACT Chad S. Hunter University of Alabama at Birmingham Comprehensive Diabetes Center 1825 University Blvd SHELBY 1211 Birmingham, AL 35294
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Yong HJ, Toledo MP, Nowakowski RS, Wang YJ. Sex Differences in the Molecular Programs of Pancreatic Cells Contribute to the Differential Risks of Type 2 Diabetes. Endocrinology 2022; 163:bqac156. [PMID: 36130190 PMCID: PMC10409906 DOI: 10.1210/endocr/bqac156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Indexed: 11/19/2022]
Abstract
Epidemiology studies demonstrate that women are at a significantly lower risk of developing type 2 diabetes (T2D) compared to men. However, the molecular basis of this risk difference is not well understood. In this study, we examined the sex differences in the genetic programs of pancreatic endocrine cells. We combined pancreas perifusion data and single-cell genomic data from our laboratory and from publicly available data sets to investigate multiple axes of the sex differences in the human pancreas at the single-cell type and single-cell level. We systematically compared female and male islet secretion function, gene expression program, and regulatory principles of pancreatic endocrine cells. The perifusion data indicate that female endocrine cells have a higher secretion capacity than male endocrine cells. Single-cell RNA-sequencing analysis suggests that endocrine cells in male controls have molecular signatures that resemble T2D. In addition, we identified genomic elements associated with genome-wide association study T2D loci to have differential accessibility between female and male delta cells. These genomic elements may play a sex-specific causal role in the pathogenesis of T2D. We provide molecular mechanisms that explain the differential risk of T2D between women and men. Knowledge gained from our study will accelerate the development of diagnostics and therapeutics in sex-aware precision medicine for diabetes.
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Affiliation(s)
- Hyo Jeong Yong
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Maria Pilar Toledo
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Richard S Nowakowski
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Yue J Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
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Liu G, Wang L, Wess J, Dean A. Enhancer looping protein LDB1 regulates hepatocyte gene expression by cooperating with liver transcription factors. Nucleic Acids Res 2022; 50:9195-9211. [PMID: 36018801 PMCID: PMC9458430 DOI: 10.1093/nar/gkac707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/22/2022] [Indexed: 12/24/2022] Open
Abstract
Enhancers establish proximity with distant target genes to regulate temporospatial gene expression and specify cell identity. Lim domain binding protein 1 (LDB1) is a conserved and widely expressed protein that functions as an enhancer looping factor. Previous studies in erythroid cells and neuronal cells showed that LDB1 forms protein complexes with different transcription factors to regulate cell-specific gene expression. Here, we show that LDB1 regulates expression of liver genes by occupying enhancer elements and cooperating with hepatic transcription factors HNF4A, FOXA1, TCF7 and GATA4. Using the glucose transporter SLC2A2 gene, encoding GLUT2, as an example, we find that LDB1 regulates gene expression by mediating enhancer-promoter interactions. In vivo, we find that LDB1 deficiency in primary mouse hepatocytes dysregulates metabolic gene expression and changes the enhancer landscape. Conditional deletion of LDB1 in adult mouse liver induces glucose intolerance. However, Ldb1 knockout hepatocytes show improved liver pathology under high-fat diet conditions associated with increased expression of genes related to liver fatty acid metabolic processes. Thus, LDB1 is linked to liver metabolic functions under normal and obesogenic conditions.
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Affiliation(s)
- Guoyou Liu
- Correspondence may also be addressed to Guoyou Liu. Tel: +1 301 435 9396;
| | - Lei Wang
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jürgen Wess
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ann Dean
- To whom correspondence should be addressed. Tel: +1 301 496 6068;
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5
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Toren E, Liu Y, Bethea M, Wade A, Hunter CS. The Ldb1 transcriptional co-regulator is required for establishment and maintenance of the pancreatic endocrine lineage. FASEB J 2022; 36:e22460. [PMID: 35881062 PMCID: PMC9397370 DOI: 10.1096/fj.202200410r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/26/2022] [Accepted: 07/08/2022] [Indexed: 11/11/2022]
Abstract
Pancreatic islet cell development is regulated by transcription factors (TFs) that mediate embryonic progenitor differentiation toward mature endocrine cells. Prior studies from our lab and others showed that the islet-enriched TF, Islet-1 (Isl1), interacts with the broadly-expressed transcriptional co-regulator, Ldb1, to regulate islet cell maturation and postnhyperatal function (by embryonic day (E)18.5). However, Ldb1 is expressed in the developing pancreas prior to Isl1 expression, notably in multipotent progenitor cells (MPCs) marked by Pdx1 and endocrine progenitors (EPs) expressing Neurogenin-3 (Ngn3). MPCs give rise to the endocrine and exocrine pancreas, while Ngn3+ EPs specify pancreatic islet endocrine cells. We hypothesized that Ldb1 is required for progenitor identity in MPC and EP populations during development to impact islet appearance and function. To test this, we generated a whole-pancreas Ldb1 knockout, termed Ldb1ΔPanc , and observed severe developmental and postnatal pancreas defects including disorganized progenitor pools, a significant reduction of Ngn3-expressing EPs, Pdx1HI β-cells, and early hormone+ cells. Ldb1ΔPanc neonates presented with severe hyperglycemia, hypoinsulinemia, and drastically reduced hormone expression in islets, yet no change in total pancreas mass. This supports the endocrine-specific actions of Ldb1. Considering this, we also developed an endocrine-enriched model of Ldb1 loss, termed Ldb1ΔEndo . We observed similar dysglycemia in this model, as well as a loss of islet identity markers. Through in vitro and in vivo chromatin immunoprecipitation experiments, we found that Ldb1 occupies key Pdx1 and Ngn3 promoter domains. Our findings provide insight into novel regulation of endocrine cell differentiation that may be vital toward improving cell-based diabetes therapies.
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Affiliation(s)
- Eliana Toren
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yanping Liu
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Maigen Bethea
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Alexa Wade
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Chad S Hunter
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
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van Gurp L, Fodoulian L, Oropeza D, Furuyama K, Bru-Tari E, Vu AN, Kaddis JS, Rodríguez I, Thorel F, Herrera PL. Generation of human islet cell type-specific identity genesets. Nat Commun 2022; 13:2020. [PMID: 35440614 PMCID: PMC9019032 DOI: 10.1038/s41467-022-29588-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/23/2022] [Indexed: 12/23/2022] Open
Abstract
Generation of surrogate cells with stable functional identities is crucial for developing cell-based therapies. Efforts to produce insulin-secreting replacement cells to treat diabetes require reliable tools to assess islet cellular identity. Here, we conduct a thorough single-cell transcriptomics meta-analysis to identify robustly expressed markers used to build genesets describing the identity of human α-, β-, γ- and δ-cells. These genesets define islet cellular identities better than previously published genesets. We show their efficacy to outline cell identity changes and unravel some of their underlying genetic mechanisms, whether during embryonic pancreas development or in experimental setups aiming at developing glucose-responsive insulin-secreting cells, such as pluripotent stem-cell differentiation or in adult islet cell reprogramming protocols. These islet cell type-specific genesets represent valuable tools that accurately benchmark gain and loss in islet cell identity traits.
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Affiliation(s)
- Léon van Gurp
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Leon Fodoulian
- Department of Genetics and Evolution, Faculty of Sciences, University of Geneva, Quai Ernest-Ansermet 30, 1211, Geneva, Switzerland
| | - Daniel Oropeza
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Kenichiro Furuyama
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara, Sakyo, 606-8507, Kyoto, Japan
| | - Eva Bru-Tari
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Anh Nguyet Vu
- Department of Diabetes & Cancer Discovery Science, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute, City of Hope, 1500 E Duarte Rd, Duarte, CA, 91010, USA
| | - John S Kaddis
- Department of Diabetes & Cancer Discovery Science, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute, City of Hope, 1500 E Duarte Rd, Duarte, CA, 91010, USA
| | - Iván Rodríguez
- Department of Genetics and Evolution, Faculty of Sciences, University of Geneva, Quai Ernest-Ansermet 30, 1211, Geneva, Switzerland
| | - Fabrizio Thorel
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, rue Michel-Servet 1, 1211, Geneva, Switzerland.
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7
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The transcriptional co-regulator LDB1 is required for brown adipose function. Mol Metab 2021; 53:101284. [PMID: 34198011 PMCID: PMC8340307 DOI: 10.1016/j.molmet.2021.101284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 11/21/2022] Open
Abstract
Objective Brown adipose tissue (BAT) is critical for thermogenesis and glucose/lipid homeostasis. Exploiting the energy uncoupling capacity of BAT may reveal targets for obesity therapies. This exploitation requires a greater understanding of the transcriptional mechanisms underlying BAT function. One potential regulator of BAT is the transcriptional co-regulator LIM domain-binding protein 1 (LDB1), which acts as a dimerized scaffold, allowing for the assembly of transcriptional complexes. Utilizing a global LDB1 heterozygous mouse model, we recently reported that LDB1 might have novel roles in regulating BAT function. However, direct evidence for the LDB1 regulation of BAT thermogenesis and substrate utilization has not been elucidated. We hypothesize that brown adipocyte-expressed LDB1 is required for BAT function. Methods LDB1-deficient primary cells and brown adipocyte cell lines were assessed via qRT-PCR and western blotting for altered mRNA and protein levels to define the brown adipose-specific roles. We conducted chromatin immunoprecipitation with primary BAT tissue and immortalized cell lines. Potential transcriptional partners of LDB1 were revealed by conducting LIM factor surveys via qRT-PCR in mouse and human brown adipocytes. We developed a Ucp1-Cre-driven LDB1-deficiency mouse model, termed Ldb1ΔBAT, to test LDB1 function in vivo. Glucose tolerance and uptake were assessed at thermoneutrality via intraperitoneal glucose challenge and glucose tracer studies. Insulin tolerance was measured at thermoneutrality and after stimulation with cold or the administration of the β3-adrenergic receptor (β3-AR) agonist CL316,243. Additionally, we analyzed plasma insulin via ELISA and insulin signaling via western blotting. Lipid metabolism was evaluated via BAT weight, histology, lipid droplet morphometry, and the examination of lipid-associated mRNA. Finally, energy expenditure and cold tolerance were evaluated via indirect calorimetry and cold challenges. Results Reducing Ldb1 in vitro and in vivo resulted in altered BAT-selective mRNA, including Ucp1, Elovl3, and Dio2. In addition, there was reduced Ucp1 induction in vitro. Impacts on gene expression may be due, in part, to LDB1 occupying Ucp1 upstream regulatory domains. We also identified BAT-expressed LIM-domain factors Lmo2, Lmo4, and Lhx8, which may partner with LDB1 to mediate activity in brown adipocytes. Additionally, we observed LDB1 enrichment in human brown adipose. In vivo analysis revealed LDB1 is required for whole-body glucose and insulin tolerance, in part through reduced glucose uptake into BAT. In Ldb1ΔBAT tissue, we found significant alterations in insulin-signaling effectors. An assessment of brown adipocyte morphology and lipid droplet size revealed larger and more unilocular brown adipocytes in Ldb1ΔBAT mice, particularly after a cold challenge. Alterations in lipid handling were further supported by reductions in mRNA associated with fatty acid oxidation and mitochondrial respiration. Finally, LDB1 is required for energy expenditure and cold tolerance in both male and female mice. Conclusions Our findings support LDB1 as a regulator of BAT function. Furthermore, given LDB1 enrichment in human brown adipose, this co-regulator may have conserved roles in human BAT. The transcriptional co-regulator LDB1 is required for brown adipocyte gene expression, including Ucp1. Several LIM-domain factors, including Lmo2, Lmo4, and Lhx8, are expressed in BAT and may be potential LDB1 partners. Male Ldb1 BAT knockouts are glucose and insulin intolerant, have lower glucose uptake and altered insulin signaling. LDB1 impacts brown adipocyte morphology, lipid droplet size, and mRNA associated with lipid utilization. BAT-expressed LDB1 is required for energy expenditure and cold tolerance.
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Davidson RK, Kanojia S, Spaeth JM. The Contribution of Transcriptional Coregulators in the Maintenance of β-cell Function and Identity. Endocrinology 2021; 162:5992209. [PMID: 33211800 PMCID: PMC7749714 DOI: 10.1210/endocr/bqaa213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Indexed: 02/02/2023]
Abstract
Islet β-cell dysfunction that leads to impaired insulin secretion is a principal source of pathology of diabetes. In type 2 diabetes, this breakdown in β-cell health is associated with compromised islet-enriched transcription factor (TF) activity that disrupts gene expression programs essential for cell function and identity. TF activity is modulated by recruited coregulators that govern activation and/or repression of target gene expression, thereby providing a supporting layer of control. To date, more than 350 coregulators have been discovered that coordinate nucleosome rearrangements, modify histones, and physically bridge general transcriptional machinery to recruited TFs; however, relatively few have been attributed to β-cell function. Here, we will describe recent findings on those coregulators with direct roles in maintaining islet β-cell health and identity and discuss how disruption of coregulator activity is associated with diabetes pathogenesis.
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Affiliation(s)
- Rebecca K Davidson
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Diabetes & Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Sukrati Kanojia
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Diabetes & Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jason M Spaeth
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Diabetes & Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
- Correspondence: Jason M. Spaeth, PhD, Department of Pediatrics, Indiana University School of Medicine, MS 2047, 635 Barnhill Drive, Indianapolis, IN 46202, USA.
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Scoville D, Lichti-Kaiser K, Grimm S, Jetten A. GLIS3 binds pancreatic beta cell regulatory regions alongside other islet transcription factors. J Endocrinol 2019; 243:JOE-19-0182.R2. [PMID: 31340201 PMCID: PMC6938561 DOI: 10.1530/joe-19-0182] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/24/2019] [Indexed: 12/13/2022]
Abstract
The Krüppel-like zinc finger transcription factor Gli-similar 3 (GLIS3) plays a critical role in the regulation of pancreatic beta cells, with global Glis3 knockout mice suffering from severe hyperglycemia and dying by post-natal day 11. In addition, GLIS3 has been shown to directly regulate the early endocrine marker Ngn3, as well as Ins2 gene expression in mature beta cells. We hypothesize that GLIS3 regulates several other genes critical to beta cell function, in addition to Ins2, by directly binding to regulatory regions. We therefore generated a pancreas-specific Glis3 deletion mouse model (Glis3Δpanc) using a Pdx1-driven Cre mouse line. Roughly 20% of these mice develop hyperglycemia by 8-weeks and lose most of their insulin expression. However, this did not appear to be due to loss of the beta cells themselves, as no change in cell death was observed. Indeed, presumptive beta cells appeared to persist as PDX1+/INS-/MAFA-/GLUT2- cells. Islet RNA-seq analysis combined with GLIS3 ChIP-seq analysis revealed apparent direct regulation of a variety of diabetes related genes, including Slc2a2 and Mafa. GLIS3 binding near these genes coincided with binding for other islet-enriched transcription factors, indicating these are distinct regulatory hubs. Our data indicates that GLIS3 not only regulates insulin expression, but several additional genes critical for beta cell function.
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Affiliation(s)
- David Scoville
- D Scoville, Immunity, Inflammation, and Disease Laboratory, NIEHS, Durham, United States
| | - Kristin Lichti-Kaiser
- K Lichti-Kaiser, Immunity, Inflammation, and Disease Laboratory, NIEHS, Durham, United States
| | - Sara Grimm
- S Grimm, Integrative Bioinformatics Support Group, NIEHS, Durham, United States
| | - Anton Jetten
- A Jetten, Immunity, Inflammation, and Disease Laboratory, NIEHS, Durham, United States
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Wade AK, Liu Y, Bethea MM, Toren E, Tse HM, Hunter CS. LIM-domain transcription complexes interact with ring-finger ubiquitin ligases and thereby impact islet β-cell function. J Biol Chem 2019; 294:11728-11740. [PMID: 31186351 DOI: 10.1074/jbc.ra118.006985] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 06/02/2019] [Indexed: 12/27/2022] Open
Abstract
Diabetes is characterized by a loss of β-cell mass, and a greater understanding of the transcriptional mechanisms governing β-cell function is required for future therapies. Previously, we reported that a complex of the Islet-1 (Isl1) transcription factor and the co-regulator single-stranded DNA-binding protein 3 (SSBP3) regulates the genes necessary for β-cell function, but few proteins are known to interact with this complex in β-cells. To identify additional components, here we performed SSBP3 reverse-cross-linked immunoprecipitation (ReCLIP)- and MS-based experiments with mouse β-cell extracts and compared the results with those from our previous Isl1 ReCLIP study. Our analysis identified the E3 ubiquitin ligases ring finger protein 20 (RNF20) and RNF40, factors that in nonpancreatic cells regulate transcription through imparting monoubiquitin marks on histone H2B (H2Bub1), a precursor to histone H3 lysine 4 trimethylation (H3K4me3). We hypothesized that RNF20 and RNF40 regulate similar genes as those regulated by Isl1 and SSBP3 and are important for β-cell function. We observed that Rnf20 and Rnf40 depletion reduces β-cell H2Bub1 marks and uncovered several target genes, including glucose transporter 2 (Glut2), MAF BZIP transcription factor A (MafA), and uncoupling protein 2 (Ucp2). Strikingly, we also observed that Isl1 and SSBP3 depletion reduces H2Bub1 and H3K4me3 marks, suggesting that they have epigenetic roles. We noted that the RNF complex is required for glucose-stimulated insulin secretion and normal mitochondrial reactive oxygen species levels. These findings indicate that RNF20 and RNF40 regulate β-cell gene expression and insulin secretion and establish a link between Isl1 complexes and global cellular epigenetics.
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Affiliation(s)
- Alexa K Wade
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Yanping Liu
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Maigen M Bethea
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Eliana Toren
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Hubert M Tse
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Chad S Hunter
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294 .,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, Alabama 35294
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11
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Enhancer long-range contacts: The multi-adaptor protein LDB1 is the tie that binds. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:625-633. [DOI: 10.1016/j.bbagrm.2019.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 11/20/2022]
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12
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Bethea M, Liu Y, Wade AK, Mullen R, Gupta R, Gelfanov V, DiMarchi R, Bhatnagar S, Behringer R, Habegger KM, Hunter CS. The islet-expressed Lhx1 transcription factor interacts with Islet-1 and contributes to glucose homeostasis. Am J Physiol Endocrinol Metab 2019; 316:E397-E409. [PMID: 30620636 PMCID: PMC6415717 DOI: 10.1152/ajpendo.00235.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The LIM-homeodomain (LIM-HD) transcription factor Islet-1 (Isl1) interacts with the LIM domain-binding protein 1 (Ldb1) coregulator to control expression of key pancreatic β-cell genes. However, Ldb1 also has Isl1-independent effects, supporting that another LIM-HD factor interacts with Ldb1 to impact β-cell development and/or function. LIM homeobox 1 (Lhx1) is an Isl1-related LIM-HD transcription factor that appears to be expressed in the developing mouse pancreas and in adult islets. However, roles for this factor in the pancreas are unknown. This study aimed to determine Lhx1 interactions and elucidate gene regulatory and physiological roles in the pancreas. Co-immunoprecipitation using β-cell extracts demonstrated an interaction between Lhx1 and Isl1, and thus we hypothesized that Lhx1 and Isl1 regulate similar target genes. To test this, we employed siRNA-mediated Lhx1 knockdown in β-cell lines and discovered reduced Glp1R mRNA. Chromatin immunoprecipitation revealed Lhx1 occupancy at a domain also known to be occupied by Isl1 and Ldb1. Through development of a pancreas-wide knockout mouse model ( Lhx1∆Panc), we demonstrate that aged Lhx1∆Panc mice have elevated fasting blood glucose levels, altered intraperitoneal and oral glucose tolerance, and significantly upregulated glucagon, somatostatin, pancreatic polypeptide, MafB, and Arx islet mRNAs. Additionally, Lhx1∆Panc mice exhibit significantly reduced Glp1R, an mRNA encoding the insulinotropic receptor for glucagon-like peptide 1 along with a concomitant dampened Glp1 response and mild glucose intolerance in mice challenged with oral glucose. These data are the first to reveal that the Lhx1 transcription factor contributes to normal glucose homeostasis and Glp1 responses.
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Affiliation(s)
- Maigen Bethea
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Yanping Liu
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Alexa K Wade
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Rachel Mullen
- Department of Genetics, The University of Texas MD Anderson Cancer Center , Houston, Texas
| | - Rajesh Gupta
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Vasily Gelfanov
- Department of Chemistry, Indiana University , Bloomington, Indiana
| | - Richard DiMarchi
- Department of Chemistry, Indiana University , Bloomington, Indiana
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Richard Behringer
- Department of Genetics, The University of Texas MD Anderson Cancer Center , Houston, Texas
| | - Kirk M Habegger
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
| | - Chad S Hunter
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham , Birmingham, Alabama
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13
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Zhang Q, Zhang Q, Jiang X, Ye Y, Liao H, Zhu F, Yan J, Luo L, Tian L, Jiang C, Chen Y, Liang X, Sun Y. Collaborative ISL1/GATA3 interaction in controlling neuroblastoma oncogenic pathways overlapping with but distinct from MYCN. Theranostics 2019; 9:986-1000. [PMID: 30867811 PMCID: PMC6401405 DOI: 10.7150/thno.30199] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/14/2019] [Indexed: 12/12/2022] Open
Abstract
Background: Transcription factor ISL1 plays a critical role in sympathetic neurogenesis. Expression of ISL1 has been associated with neuroblastoma, a pediatric tumor derived from sympatho-adrenal progenitors, however the role of ISL1 in neuroblastoma remains unexplored. Method: Here, we knocked down ISL1 (KD) in SH-SY5Y neuroblastoma cells and performed RNA-seq and ISL1 ChIP-seq analyses. Results: Analyses of these data revealed that ISL1 acts upstream of multiple oncogenic genes and pathways essential for neuroblastoma proliferation and differentiation, including LMO1 and LIN28B. ISL1 promotes expression of a number of cell cycle associated genes, but represses differentiation associated genes including RA receptors and the downstream target genes EPAS1 and CDKN1A. Consequently, Knockdown of ISL1 inhibits neuroblastoma cell proliferation and migration in vitro and impedes tumor growth in vivo, and enhances neuronal differentiation by RA treatment. Furthermore, genome-wide mapping revealed a substantial co-occupancy of binding regions by ISL1 and GATA3, and ISL1 physically interacts with GATA3, and together they synergistically regulate the aforementioned oncogenic pathways. In addition, analyses of the roles of ISL1 and MYCN in MYCN-amplified and MYCN non-amplified neuroblastoma cells revealed an epistatic relationship between ISL1 and MYCN. ISL1 and MYCN function in parallel to regulate common yet distinct oncogenic pathways in neuroblastoma. Conclusion: Our study has demonstrated that ISL1 plays an essential role in neuroblastoma regulatory networks and may serve as a potential therapeutic target in neuroblastoma.
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14
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Ching ST, Infante CR, Du W, Sharir A, Park S, Menke DB, Klein OD. Isl1 mediates mesenchymal expansion in the developing external genitalia via regulation of Bmp4, Fgf10 and Wnt5a. Hum Mol Genet 2019; 27:107-119. [PMID: 29126155 DOI: 10.1093/hmg/ddx388] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 10/25/2017] [Indexed: 12/20/2022] Open
Abstract
Genital malformations are among the most common human birth defects, and both genetic and environmental factors can contribute to these malformations. Development of the external genitalia in mammals relies on complex signaling networks, and disruption of these signaling pathways can lead to genital defects. Islet-1 (ISL1), a member of the LIM/Homeobox family of transcription factors, has been identified as a major susceptibility gene for classic bladder exstrophy in humans, a common form of the bladder exstrophy-epispadias complex (BEEC), and is implicated in a role in urinary tract development. We report that deletion of Isl1 from the genital mesenchyme in mice led to hypoplasia of the genital tubercle and prepuce, with an ectopic urethral opening and epispadias-like phenotype. These mice also developed hydroureter and hydronephrosis. Identification of ISL1 transcriptional targets via ChIP-Seq and expression analyses revealed that Isl1 regulates several important signaling pathways during embryonic genital development, including the BMP, WNT, and FGF cascades. An essential function of Isl1 during development of the external genitalia is to induce Bmp4-mediated apoptosis in the genital mesenchyme. Together, these studies demonstrate that Isl1 plays a critical role during development of the external genitalia and forms the basis for a greater understanding of the molecular mechanisms underlying the pathogenesis of BEEC and urinary tract defects in humans.
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Affiliation(s)
- Saunders T Ching
- Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA
| | - Carlos R Infante
- Department of Genetics, University of Georgia, GA 30602, USA.,Department of Molecular and Cellular Biology, University of Arizona, AZ 85721, USA
| | - Wen Du
- Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA.,State Key Laboratory of Oral Diseases, Department of Prosthetics, West China College of Stomatology, Sichuan University, Sichuan Sheng 610041, China
| | - Amnon Sharir
- Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA
| | - Sungdae Park
- Department of Genetics, University of Georgia, GA 30602, USA
| | - Douglas B Menke
- Department of Genetics, University of Georgia, GA 30602, USA
| | - Ophir D Klein
- Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA.,Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, CA 94143, USA
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15
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Shao W, Szeto V, Song Z, Tian L, Feng ZP, Nostro MC, Jin T. The LIM homeodomain protein ISL1 mediates the function of TCF7L2 in pancreatic beta cells. J Mol Endocrinol 2018; 61:1-12. [PMID: 29678908 DOI: 10.1530/jme-17-0181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 03/29/2018] [Indexed: 11/08/2022]
Abstract
Pancreatic β-cell Tcf7l2 deletion or its functional knockdown suggested the essential role of this Wnt pathway effector in controlling insulin secretion, glucose homeostasis and β-cell gene expression. As the LIM homeodomain protein ISL1 is a suggested Wnt pathway downstream target, we hypothesize that it mediates metabolic functions of TCF7L2. We aimed to determine the role of ISL1 in mediating the function of TCF7L2 and the incretin hormone GLP-1 in pancreatic β-cells. The effect of dominant negative TCF7L2 (TCF7L2DN) mediated Wnt pathway functional knockdown on Isl1 expression was determined in βTCFDN mouse islets and in the rat insulinoma cell line INS-1 832/13. Luciferase reporter assay and chromatin immunoprecipitation were utilized to determine whether Isl1 is a direct downstream target of Tcf7l2 TCF7L2DN adenovirus infection and siRNA-mediated Isl1 knockdown on β-cell gene expression were compared. Furthermore, Isl1 knockdown on GLP-1 stimulated β-catenin S675 phosphorylation and insulin secretion was determined. We found that TCF7L2DN repressed ISL1 levels in βTCFDN islets and the INS-1 832/13 cell line. Wnt stimulators enhanced Isl1 promoter activity and binding of TCF7L2 on Isl1 promoter. TCF7L2DN adenovirus infection and Isl1 knockdown generated similar repression on expression of β-cell genes, including the ones that encode GLUT2 and GLP-1 receptor. Either TCF7L2DN adenovirus infection or Isl1 knockdown attenuated GLP-1-stimulated β-catenin S675 phosphorylation in INS-1 832/13 cells or mouse islets and GLP-1 stimulated insulin secretion in INS-1 832/13 or MIN6 cells. Our observations support the existence of TCF7L2-ISL1 transcriptional network, and we suggest that this network also mediates β-cell function of GLP-1.
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Affiliation(s)
- Weijuan Shao
- Division of Advanced DiagnosticsToronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Vivian Szeto
- Department of PhysiologyUniversity of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
| | - Zhuolun Song
- Department of PhysiologyUniversity of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
| | - Lili Tian
- Division of Advanced DiagnosticsToronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Zhong-Ping Feng
- Department of PhysiologyUniversity of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
| | - M Cristina Nostro
- Department of PhysiologyUniversity of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
- Division of Experimental TherapeuticsToronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- McEwen Centre for Regenerative MedicineUniversity Health Network, Toronto, Ontario, Canada
| | - Tianru Jin
- Division of Advanced DiagnosticsToronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of PhysiologyUniversity of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
- McEwen Centre for Regenerative MedicineUniversity Health Network, Toronto, Ontario, Canada
- Banting and Best Diabetes CenterUniversity of Toronto, Toronto, Ontario, Canada
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16
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Jung Y, Zhou R, Kato T, Usui JK, Muratani M, Oishi H, Heck MMS, Takahashi S. Isl1β Overexpression With Key β Cell Transcription Factors Enhances Glucose-Responsive Hepatic Insulin Production and Secretion. Endocrinology 2018; 159:869-882. [PMID: 29220426 DOI: 10.1210/en.2017-00663] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 12/01/2017] [Indexed: 11/19/2022]
Abstract
Adenoviral gene transfer of key β cell developmental regulators including Pdx1, Neurod1, and Mafa (PDA) has been reported to generate insulin-producing cells in the liver. However, PDA insulin secretion is transient and glucose unresponsive. Here, we report that an additional β cell developmental regulator, insulin gene enhancer binding protein splicing variant (Isl1β), improved insulin production and glucose-responsive secretion in PDA mice. Microarray gene expression analysis suggested that adenoviral PDA transfer required an additional element for mature β cell generation, such as Isl1 and Elf3 in the liver. In vitro promoter analysis indicated that splicing variant Isl1, or Isl1β, is an important factor for transcriptional activity of the insulin gene. In vivo bioluminescence monitoring using insulin promoter-luciferase transgenic mice verified that adenoviral PDA + Isl1β transfer produced highly intense luminescence from the liver, which peaked at day 7 and persisted for more than 10 days. Using insulin promoter-GFP transgenic mice, we further confirmed that Isl1β supplementation to PDA augmented insulin-producing cells in the liver, insulin production and secretion, and β cell‒related genes. Finally, the PDA + Isl1β combination ameliorated hyperglycemia in diabetic mice for 28 days and enhanced glucose tolerance and responsiveness. Thus, our results suggest that Isl1β is a key additional transcriptional factor for advancing the generation of insulin-producing cells in the liver in combination with PDA.
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Affiliation(s)
- Yunshin Jung
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
- School of Integrative and Global Majors, University of Tsukuba, Tennodai, Japan
| | - Ruyi Zhou
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
| | - Toshiki Kato
- School of Integrative and Global Majors, University of Tsukuba, Tennodai, Japan
- Department of Regenerative Medicine and Stem Cell Biology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
| | - Jeffrey K Usui
- School of Medicine, Stony Brook University, Stony Brook, New York
| | - Masafumi Muratani
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
- School of Integrative and Global Majors, University of Tsukuba, Tennodai, Japan
| | - Hisashi Oishi
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
- Life Science Center, Tsukuba Advanced Research Alliance, University of Tsukuba, Tennodai, Japan
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Tennodai, Japan
| | - Margarete M S Heck
- Queen's Medical Research Institute, University/BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom
| | - Satoru Takahashi
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tennodai, Japan
- Life Science Center, Tsukuba Advanced Research Alliance, University of Tsukuba, Tennodai, Japan
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Tennodai, Japan
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17
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Naveau A, Zhang B, Meng B, Sutherland MT, Prochazkova M, Wen T, Marangoni P, Jones KB, Cox TC, Ganss B, Jheon AH, Klein OD. Isl1 Controls Patterning and Mineralization of Enamel in the Continuously Renewing Mouse Incisor. J Bone Miner Res 2017; 32:2219-2231. [PMID: 28650075 PMCID: PMC5685895 DOI: 10.1002/jbmr.3202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 06/09/2017] [Accepted: 06/21/2017] [Indexed: 01/15/2023]
Abstract
Rodents are characterized by continuously renewing incisors whose growth is fueled by epithelial and mesenchymal stem cells housed in the proximal compartments of the tooth. The epithelial stem cells reside in structures known as the labial (toward the lip) and lingual (toward the tongue) cervical loops (laCL and liCL, respectively). An important feature of the rodent incisor is that enamel, the outer, highly mineralized layer, is asymmetrically distributed, because it is normally generated by the laCL but not the liCL. Here, we show that epithelial-specific deletion of the transcription factor Islet1 (Isl1) is sufficient to drive formation of ectopic enamel by the liCL stem cells, and also that it leads to production of altered enamel on the labial surface. Molecular analyses of developing and adult incisors revealed that epithelial deletion of Isl1 affected multiple, major pathways: Bmp (bone morphogenetic protein), Hh (hedgehog), Fgf (fibroblast growth factor), and Notch signaling were upregulated and associated with liCL-generated ectopic enamel; on the labial side, upregulation of Bmp and Fgf signaling, and downregulation of Shh were associated with premature enamel formation. Transcriptome profiling studies identified a suite of differentially regulated genes in developing Isl1 mutant incisors. Our studies demonstrate that ISL1 plays a central role in proper patterning of stem cell-derived enamel in the incisor and indicate that this factor is an important upstream regulator of signaling pathways during tooth development and renewal. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Adrien Naveau
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
- Université Paris Descartes, Sorbonne Paris Cite, UMR S872, France
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, UMR S872, Paris, France
- INSERM U872, Paris, France
| | - Bin Zhang
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Bo Meng
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - McGarrett T. Sutherland
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Michaela Prochazkova
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
- Laboratory of Transgenic Models of Diseases, Institute of Molecular Genetics of the ASCR, v.v.i., Prague 4 14220, Czech Republic
| | - Timothy Wen
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Pauline Marangoni
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Kyle B. Jones
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Timothy C. Cox
- Department of Pediatrics (Craniofacial Medicine), University of Washington & Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Bernhard Ganss
- Faculty of Dentistry, University of Toronto, Toronto, ON Canada
| | - Andrew H. Jheon
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Ophir D. Klein
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA
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18
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Lawlor N, Youn A, Kursawe R, Ucar D, Stitzel ML. Alpha TC1 and Beta-TC-6 genomic profiling uncovers both shared and distinct transcriptional regulatory features with their primary islet counterparts. Sci Rep 2017; 7:11959. [PMID: 28931935 PMCID: PMC5607285 DOI: 10.1038/s41598-017-12335-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/06/2017] [Indexed: 01/09/2023] Open
Abstract
Alpha TC1 (αTC1) and Beta-TC-6 (βTC6) mouse islet cell lines are cellular models of islet (dys)function and type 2 diabetes (T2D). However, genomic characteristics of these cells, and their similarities to primary islet alpha and beta cells, are undefined. Here, we report the epigenomic (ATAC-seq) and transcriptomic (RNA-seq) landscapes of αTC1 and βTC6 cells. Each cell type exhibits hallmarks of its primary islet cell counterpart including cell-specific expression of beta (e.g., Pdx1) and alpha (e.g., Arx) cell transcription factors (TFs), and enrichment of binding motifs for these TFs in αTC1/βTC6 cis-regulatory elements. αTC1/βTC6 transcriptomes overlap significantly with the transcriptomes of primary mouse/human alpha and beta cells. Our data further indicate that ATAC-seq detects cell-specific regulatory elements for cell types comprising ≥ 20% of a mixed cell population. We identified αTC1/βTC6 cis-regulatory elements orthologous to those containing type 2 diabetes (T2D)-associated SNPs in human islets for 33 loci, suggesting these cells’ utility to dissect T2D molecular genetics in these regions. Together, these maps provide important insights into the conserved regulatory architecture between αTC1/βTC6 and primary islet cells that can be leveraged in functional (epi)genomic approaches to dissect the genetic and molecular factors controlling islet cell identity and function.
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Affiliation(s)
- Nathan Lawlor
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Ahrim Youn
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Romy Kursawe
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Duygu Ucar
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA. .,Institute for Systems Genomics, University of Connecticut, Farmington, CT, 06032, USA. .,Department of Genetics & Genome Sciences, University of Connecticut, Farmington, CT, 06032, USA.
| | - Michael L Stitzel
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA. .,Institute for Systems Genomics, University of Connecticut, Farmington, CT, 06032, USA. .,Department of Genetics & Genome Sciences, University of Connecticut, Farmington, CT, 06032, USA.
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19
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Loyd C, Liu Y, Kim T, Holleman C, Galloway J, Bethea M, Ediger BN, Swain TA, Tang Y, Stoffers DA, Rowe GC, Young M, Steele C, Habegger KM, Hunter CS. LDB1 Regulates Energy Homeostasis During Diet-Induced Obesity. Endocrinology 2017; 158:1289-1297. [PMID: 28009534 PMCID: PMC5460834 DOI: 10.1210/en.2016-1791] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/22/2016] [Indexed: 12/21/2022]
Abstract
The broadly expressed transcriptional coregulator LDB1 is essential for β-cell development and glucose homeostasis. However, it is unclear whether LDB1 has metabolic roles beyond the β-cell, especially under metabolic stress. Global Ldb1 deletion results in early embryonic lethality; thus, we used global heterozygous Ldb1+/- and inducible β-cell-specific Ldb1-deficient (Ldb1Δβ-cell) mice. We assessed glucose and insulin tolerance, body composition, feeding, and energy expenditure during high-fat diet exposure. Brown adipose tissue (BAT) biology was evaluated by thermogenic gene expression and LDB1 chromatin immunoprecipitation analysis. We found that partial loss of Ldb1 does not impair the maintenance of glucose homeostasis; rather, we observed improved insulin sensitivity in these mice. Partial loss of Ldb1 also uncovered defects in energy expenditure in lean and diet-induced obese (DIO) mice. This decreased energy expenditure during DIO was associated with significantly altered BAT gene expression, specifically Cidea, Elovl3, Cox7a1, and Dio2. Remarkably, the observed changes in energy balance during DIO were absent in Ldb1Δβ-cell mice, despite a similar reduction in plasma insulin, suggesting a role for LDB1 in BAT. Indeed, LDB1 is expressed in brown adipocytes and occupies a regulatory domain of Elovl3, a gene crucial to normal BAT function. We conclude that LDB1 regulates energy homeostasis, in part through transcriptional modulation of critical regulators in BAT function.
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Affiliation(s)
- Christine Loyd
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Yanping Liu
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Teayoun Kim
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Cassie Holleman
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Jamie Galloway
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Maigen Bethea
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Benjamin N. Ediger
- Institute for Diabetes, Obesity, and Metabolism and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | | | - Yawen Tang
- Department of Medicine, Division of Cardiovascular Disease, and
| | - Doris A. Stoffers
- Institute for Diabetes, Obesity, and Metabolism and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Glenn C. Rowe
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
- Department of Medicine, Division of Cardiovascular Disease, and
| | - Martin Young
- Department of Medicine, Division of Cardiovascular Disease, and
| | - Chad Steele
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Kirk M. Habegger
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
| | - Chad S. Hunter
- Comprehensive Diabetes Center and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism
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20
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Sims EK. Chewing the Fat: A Metabolic Role for Ldb1 Beyond the Pancreas? Endocrinology 2017; 158:1113-1115. [PMID: 28609835 PMCID: PMC5460831 DOI: 10.1210/en.2017-00080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 01/20/2017] [Indexed: 11/19/2022]
Affiliation(s)
- Emily K Sims
- Department of Pediatrics and Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana 46202
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21
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Ediger BN, Lim HW, Juliana C, Groff DN, Williams LT, Dominguez G, Liu JH, Taylor BL, Walp ER, Kameswaran V, Yang J, Liu C, Hunter CS, Kaestner KH, Naji A, Li C, Sander M, Stein R, Sussel L, Won KJ, May CL, Stoffers DA. LIM domain-binding 1 maintains the terminally differentiated state of pancreatic β cells. J Clin Invest 2016; 127:215-229. [PMID: 27941246 DOI: 10.1172/jci88016] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/13/2016] [Indexed: 12/11/2022] Open
Abstract
The recognition of β cell dedifferentiation in type 2 diabetes raises the translational relevance of mechanisms that direct and maintain β cell identity. LIM domain-binding protein 1 (LDB1) nucleates multimeric transcriptional complexes and establishes promoter-enhancer looping, thereby directing fate assignment and maturation of progenitor populations. Many terminally differentiated endocrine cell types, however, remain enriched for LDB1, but its role is unknown. Here, we have demonstrated a requirement for LDB1 in maintaining the terminally differentiated status of pancreatic β cells. Inducible ablation of LDB1 in mature β cells impaired insulin secretion and glucose homeostasis. Transcriptomic analysis of LDB1-depleted β cells revealed the collapse of the terminally differentiated gene program, indicated by a loss of β cell identity genes and induction of the endocrine progenitor factor neurogenin 3 (NEUROG3). Lineage tracing confirmed that LDB1-depleted, insulin-negative β cells express NEUROG3 but do not adopt alternate endocrine cell fates. In primary mouse islets, LDB1 and its LIM homeodomain-binding partner islet 1 (ISL1) were coenriched at chromatin sites occupied by pancreatic and duodenal homeobox 1 (PDX1), NK6 homeobox 1 (NKX6.1), forkhead box A2 (FOXA2), and NK2 homeobox 2 (NKX2.2) - factors that co-occupy active enhancers in 3D chromatin domains in human islets. Indeed, LDB1 was enriched at active enhancers in human islets. Thus, LDB1 maintains the terminally differentiated state of β cells and is a component of active enhancers in both murine and human islets.
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22
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Pasek RC, Dunn JC, Elsakr JM, Aramandla M, Matta AR, Gannon M. Connective tissue growth factor is critical for proper β-cell function and pregnancy-induced β-cell hyperplasia in adult mice. Am J Physiol Endocrinol Metab 2016; 311:E564-74. [PMID: 27460898 PMCID: PMC5142004 DOI: 10.1152/ajpendo.00194.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/25/2016] [Indexed: 01/09/2023]
Abstract
During pregnancy, maternal β-cells undergo compensatory changes, including increased β-cell mass and enhanced glucose-stimulated insulin secretion. Failure of these adaptations to occur results in gestational diabetes mellitus. The secreted protein connective tissue growth factor (CTGF) is critical for normal β-cell development and promotes regeneration after partial β-cell ablation. During embryogenesis, CTGF is expressed in pancreatic ducts, vasculature, and β-cells. In adult pancreas, CTGF is expressed only in the vasculature. Here we show that pregnant mice with global Ctgf haploinsufficiency (Ctgf(LacZ/+)) have an impairment in maternal β-cell proliferation; no difference was observed in virgin Ctgf(LacZ/+) females. Using a conditional CTGF allele, we found that mice with a specific inactivation of CTGF in endocrine cells (Ctgf(ΔEndo)) develop gestational diabetes during pregnancy, but this is due to a reduction in glucose-stimulated insulin secretion rather than impaired maternal β-cell proliferation. Moreover, virgin Ctgf(ΔEndo) females also display impaired GSIS with glucose intolerance, indicating that underlying β-cell dysfunction precedes the development of gestational diabetes in this animal model. This is the first time a role for CTGF in β-cell function has been reported.
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Affiliation(s)
- Raymond C Pasek
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jennifer C Dunn
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Joseph M Elsakr
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee; and
| | - Mounika Aramandla
- School for Science and Math, Vanderbilt University, Nashville, Tennessee
| | - Anveetha R Matta
- School for Science and Math, Vanderbilt University, Nashville, Tennessee
| | - Maureen Gannon
- Department of Veterans Affairs Tennessee Valley, Nashville, Tennessee; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee; and
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23
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Spaeth JM, Walker EM, Stein R. Impact of Pdx1-associated chromatin modifiers on islet β-cells. Diabetes Obes Metab 2016; 18 Suppl 1:123-7. [PMID: 27615141 PMCID: PMC5918695 DOI: 10.1111/dom.12730] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/03/2016] [Indexed: 12/11/2022]
Abstract
Diabetes mellitus arises from insufficient insulin secretion from pancreatic islet β-cells. In type 2 diabetes (T2D), β-cell dysfunction is associated with inactivation and/or loss of transcription factor (TF) activity, including Pdx1. Notably, this particular TF is viewed as a master regulator of pancreas development and islet β-cell formation, identity and function. TFs, like Pdx1, recruit coregulators to transduce activating and/or repressing signals to the general transcriptional machinery for controlling gene expression, including modifiers of DNA, histones and nucleosome architecture. These coregulators impart a secondary layer of control that can be exploited to modulate TF activity. In this review, we describe Pdx1-recruited coregulators that impact chromatin structure, consequently influencing normal β-cell function and likely Pdx1 activity in pathophysiological settings.
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Affiliation(s)
- J M Spaeth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - E M Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - R Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.
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24
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Abstract
Lineage tracing studies have revealed that transcription factors play a cardinal role in pancreatic development, differentiation and function. Three transitions define pancreatic organogenesis, differentiation and maturation. In the primary transition, when pancreatic organogenesis is initiated, there is active proliferation of pancreatic progenitor cells. During the secondary transition, defined by differentiation, there is growth, branching, differentiation and pancreatic cell lineage allocation. The tertiary transition is characterized by differentiated pancreatic cells that undergo further remodeling, including apoptosis, replication and neogenesis thereby establishing a mature organ. Transcription factors function at multiple levels and may regulate one another and auto-regulate. The interaction between extrinsic signals from non-pancreatic tissues and intrinsic transcription factors form a complex gene regulatory network ultimately culminating in the different cell lineages and tissue types in the developing pancreas. Mutations in these transcription factors clinically manifest as subtypes of diabetes mellitus. Current treatment for diabetes is not curative and thus, developmental biologists and stem cell researchers are utilizing knowledge of normal pancreatic development to explore novel therapeutic alternatives. This review summarizes current knowledge of transcription factors involved in pancreatic development and β-cell differentiation in rodents.
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Affiliation(s)
- Reshmi Dassaye
- a Discipline of Pharmaceutical Sciences; Nelson R. Mandela School of Medicine, University of KwaZulu-Natal , Durban , South Africa
| | - Strini Naidoo
- a Discipline of Pharmaceutical Sciences; Nelson R. Mandela School of Medicine, University of KwaZulu-Natal , Durban , South Africa
| | - Marlon E Cerf
- b Diabetes Discovery Platform, South African Medical Research Council , Cape Town , South Africa
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25
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Galloway JR, Bethea M, Liu Y, Underwood R, Mobley JA, Hunter CS. SSBP3 Interacts With Islet-1 and Ldb1 to Impact Pancreatic β-Cell Target Genes. Mol Endocrinol 2015; 29:1774-86. [PMID: 26495868 DOI: 10.1210/me.2015-1165] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Islet-1 (Isl1) is a Lin11, Isl1, Mec3 (LIM)-homeodomain transcription factor important for pancreatic islet cell development, maturation, and function, which largely requires interaction with the LIM domain-binding protein 1 (Ldb1) coregulator. In other tissues, Ldb1 and Isl1 interact with additional factors to mediate target gene transcription, yet few protein partners are known in β-cells. Therefore, we hypothesize that Ldb1 and Isl1 participate in larger regulatory complexes to impact β-cell gene expression. To test this, we used cross-linked immunoprecipitation and mass spectrometry to identify interacting proteins from mouse β-cells. Proteomic datasets revealed numerous interacting candidates, including a member of the single-stranded DNA-binding protein (SSBP) coregulator family, SSBP3. SSBPs potentiate LIM transcription factor complex activity and stability in other tissues. However, nothing was known of SSBP3 interaction, expression, or activity in β-cells. Our analyses confirmed that SSBP3 interacts with Ldb1 and Isl1 in β-cell lines and in mouse and human islets and demonstrated SSBP3 coexpression with Ldb1 and Isl1 pancreas tissue. Furthermore, β-cell line SSBP3 knockdown imparted mRNA deficiencies similar to those observed upon Ldb1 reduction in vitro or in vivo. This appears to be (at least) due to SSBP3 occupancy of known Ldb1-Isl1 target promoters, including MafA and Glp1r. This study collectively demonstrates that SSBP3 is a critical component of Ldb1-Isl1 regulatory complexes, required for expression of critical β-cell target genes.
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Affiliation(s)
- Jamie R Galloway
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Maigen Bethea
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Yanping Liu
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Rachel Underwood
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - James A Mobley
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Chad S Hunter
- Department of Medicine (J.R.G., M.B., Y.L., R.U., C.S.H.), Division of Endocrinology, Diabetes and Metabolism, and Comprehensive Diabetes Center, and Department of Surgery (J.A.M.), University of Alabama at Birmingham, Birmingham, Alabama 35294
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26
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Islet 1 specifies the identity of hypothalamic melanocortin neurons and is critical for normal food intake and adiposity in adulthood. Proc Natl Acad Sci U S A 2015; 112:E1861-70. [PMID: 25825735 DOI: 10.1073/pnas.1500672112] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Food intake and body weight regulation depend on proper expression of the proopiomelanocortin gene (Pomc) in a group of neurons located in the mediobasal hypothalamus of all vertebrates. These neurons release POMC-encoded melanocortins, which are potent anorexigenic neuropeptides, and their absence from mice or humans leads to hyperphagia and severe obesity. Although the pathophysiology of hypothalamic POMC neurons is well understood, the genetic program that establishes the neuronal melanocortinergic phenotype and maintains a fully functional neuronal POMC phenotype throughout adulthood remains unknown. Here, we report that the early expression of the LIM-homeodomain transcription factor Islet 1 (ISL1) in the developing hypothalamus promotes the terminal differentiation of melanocortinergic neurons and is essential for hypothalamic Pomc expression since its initial onset and throughout the entire lifetime. We detected ISL1 in the prospective hypothalamus just before the onset of Pomc expression and, from then on, Pomc and Isl1 coexpress. ISL1 binds in vitro and in vivo to critical homeodomain binding DNA motifs present in the neuronal Pomc enhancers nPE1 and nPE2, and mutations of these sites completely disrupt the ability of these enhancers to drive reporter gene expression to hypothalamic POMC neurons in transgenic mice and zebrafish. ISL1 is necessary for hypothalamic Pomc expression during mouse and zebrafish embryogenesis. Furthermore, conditional Isl1 inactivation from POMC neurons impairs Pomc expression, leading to hyperphagia and obesity. Our results demonstrate that ISL1 specifies the identity of hypothalamic melanocortin neurons and is required for melanocortin-induced satiety and normal adiposity throughout the entire lifespan.
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27
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McKenna B, Guo M, Reynolds A, Hara M, Stein R. Dynamic recruitment of functionally distinct Swi/Snf chromatin remodeling complexes modulates Pdx1 activity in islet β cells. Cell Rep 2015; 10:2032-42. [PMID: 25801033 DOI: 10.1016/j.celrep.2015.02.054] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 01/21/2015] [Accepted: 02/23/2015] [Indexed: 02/03/2023] Open
Abstract
Pdx1 is a transcription factor of fundamental importance to pancreas formation and adult islet β cell function. However, little is known about the positive- and negative-acting coregulators recruited to mediate transcriptional control. Here, we isolated numerous Pdx1-interacting factors possessing a wide range of cellular functions linked with this protein, including, but not limited to, coregulators associated with transcriptional activation and repression, DNA damage response, and DNA replication. Because chromatin remodeling activities are essential to developmental lineage decisions and adult cell function, our analysis focused on investigating the influence of the Swi/Snf chromatin remodeler on Pdx1 action. The two mutually exclusive and indispensable Swi/Snf core ATPase subunits, Brg1 and Brm, distinctly affected target gene expression in β cells. Furthermore, physiological and pathophysiological conditions dynamically regulated Pdx1 binding to these Swi/Snf complexes in vivo. We discuss how context-dependent recruitment of coregulatory complexes by Pdx1 could impact pancreas cell development and adult islet β cell activity.
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Affiliation(s)
- Brian McKenna
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Min Guo
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Albert Reynolds
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Manami Hara
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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28
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Gu W, Monteiro R, Zuo J, Simões FC, Martella A, Andrieu-Soler C, Grosveld F, Sauka-Spengler T, Patient R. A novel TGFβ modulator that uncouples R-Smad/I-Smad-mediated negative feedback from R-Smad/ligand-driven positive feedback. PLoS Biol 2015; 13:e1002051. [PMID: 25665164 PMCID: PMC4321984 DOI: 10.1371/journal.pbio.1002051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/17/2014] [Indexed: 01/17/2023] Open
Abstract
As some of the most widely utilised intercellular signalling molecules, transforming growth factor β (TGFβ) superfamily members play critical roles in normal development and become disrupted in human disease. Establishing appropriate levels of TGFβ signalling involves positive and negative feedback, which are coupled and driven by the same signal transduction components (R-Smad transcription factor complexes), but whether and how the regulation of the two can be distinguished are unknown. Genome-wide comparison of published ChIP-seq datasets suggests that LIM domain binding proteins (Ldbs) co-localise with R-Smads at a substantial subset of R-Smad target genes including the locus of inhibitory Smad7 (I-Smad7), which mediates negative feedback for TGFβ signalling. We present evidence suggesting that zebrafish Ldb2a binds and directly activates the I-Smad7 gene, whereas it binds and represses the ligand gene, Squint (Sqt), which drives positive feedback. Thus, the fine tuning of TGFβ signalling derives from positive and negative control by Ldb2a. Expression of ldb2a is itself activated by TGFβ signals, suggesting potential feed-forward loops that might delay the negative input of Ldb2a to the positive feedback, as well as the positive input of Ldb2a to the negative feedback. In this way, precise gene expression control by Ldb2a enables an initial build-up of signalling via a fully active positive feedback in the absence of buffering by the negative feedback. In Ldb2a-deficient zebrafish embryos, homeostasis of TGFβ signalling is perturbed and signalling is stably enhanced, giving rise to excess mesoderm and endoderm, an effect that can be rescued by reducing signalling by the TGFβ family members, Nodal and BMP. Thus, Ldb2a is critical to the homeostatic control of TGFβ signalling and thereby embryonic patterning.
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Affiliation(s)
- Wenchao Gu
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Rui Monteiro
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- BHF Centre of Research Excellence, Oxford, United Kingdom
| | - Jie Zuo
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Filipa Costa Simões
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Andrea Martella
- Department of Cell Biology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Charlotte Andrieu-Soler
- INSERM U872, Université René Descartes Sorbonne Paris Cité, Team 17, Centre de Recherche des Cordeliers, Paris, France
| | - Frank Grosveld
- Department of Cell Biology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Tatjana Sauka-Spengler
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Roger Patient
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- BHF Centre of Research Excellence, Oxford, United Kingdom
- * E-mail:
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29
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Brun PJ, Grijalva A, Rausch R, Watson E, Yuen JJ, Das BC, Shudo K, Kagechika H, Leibel RL, Blaner WS. Retinoic acid receptor signaling is required to maintain glucose-stimulated insulin secretion and β-cell mass. FASEB J 2015; 29. [PMID: 25389133 PMCID: PMC4314234 DOI: 10.1096/fj.14-256743 10.1096/fj.14-256743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Retinoic acid signaling is required for maintaining a range of cellular processes, including cell differentiation, proliferation, and apoptosis. We investigated the actions of all-trans-retinoic acid (atRA) signaling in pancreatic β-cells of adult mice. atRA signaling was ablated in β-cells by overexpressing a dominant-negative retinoic acid receptor (RAR)-α mutant (RARdn) using an inducible Cre-Lox system under the control of the pancreas duodenal homeobox gene promoter. Our studies establish that hypomorphism for RAR in β-cells leads to an age-dependent decrease in plasma insulin in the fed state and in response to a glucose challenge. Glucose-stimulated insulin secretion was also impaired in islets isolated from mice expressing RARdn. Among genes that are atRA responsive, Glut2 and Gck mRNA levels were decreased in isolated islets from RARdn-expressing mice. Histologic analyses of RARdn-expressing pancreata revealed a decrease in β-cell mass and insulin per β-cell 1 mo after induction of the RARdn. Our results indicate that atRA signaling mediated by RARs is required in the adult pancreas for maintaining both β-cell function and mass, and provide insights into molecular mechanisms underlying these actions.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - William S. Blaner
- Correspondence: Department of Medicine, College of Physicians and Surgeons, Columbia University, 630 W. 168th Street, New York, NY 10032, USA. E-mail:
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30
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Ediger BN, Du A, Liu J, Hunter CS, Walp ER, Schug J, Kaestner KH, Stein R, Stoffers DA, May CL. Islet-1 Is essential for pancreatic β-cell function. Diabetes 2014; 63:4206-17. [PMID: 25028525 PMCID: PMC4237994 DOI: 10.2337/db14-0096] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Islet-1 (Isl-1) is essential for the survival and ensuing differentiation of pancreatic endocrine progenitors. Isl-1 remains expressed in all adult pancreatic endocrine lineages; however, its specific function in the postnatal pancreas is unclear. Here we determine whether Isl-1 plays a distinct role in the postnatal β-cell by performing physiological and morphometric analyses of a tamoxifen-inducible, β-cell-specific Isl-1 loss-of-function mouse: Isl-1(L/L); Pdx1-CreER(Tm). Ablating Isl-1 in postnatal β-cells reduced glucose tolerance without significantly reducing β-cell mass or increasing β-cell apoptosis. Rather, islets from Isl-1(L/L); Pdx1-CreER(Tm) mice showed impaired insulin secretion. To identify direct targets of Isl-1, we integrated high-throughput gene expression and Isl-1 chromatin occupancy using islets from Isl-1(L/L); Pdx1-CreER(Tm) mice and βTC3 insulinoma cells, respectively. Ablating Isl-1 significantly affected the β-cell transcriptome, including known targets Insulin and MafA as well as novel targets Pdx1 and Slc2a2. Using chromatin immunoprecipitation sequencing and luciferase reporter assays, we found that Isl-1 directly occupies functional regulatory elements of Pdx1 and Slc2a2. Thus Isl-1 is essential for postnatal β-cell function, directly regulates Pdx1 and Slc2a2, and has a mature β-cell cistrome distinct from that of pancreatic endocrine progenitors.
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Affiliation(s)
- Benjamin N Ediger
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Aiping Du
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Jingxuan Liu
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Chad S Hunter
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Erik R Walp
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Jonathan Schug
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Doris A Stoffers
- Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Catherine L May
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Janssen Research & Development, Spring House, PA
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31
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Thompson JM, Di Gregorio A. Insulin-like genes in ascidians: findings in Ciona and hypotheses on the evolutionary origins of the pancreas. Genesis 2014; 53:82-104. [PMID: 25378051 DOI: 10.1002/dvg.22832] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 10/13/2014] [Accepted: 10/16/2014] [Indexed: 12/22/2022]
Abstract
Insulin plays an extensively characterized role in the control of sugar metabolism, growth and homeostasis in a wide range of organisms. In vertebrate chordates, insulin is mainly produced by the beta cells of the endocrine pancreas, while in non-chordate animals insulin-producing cells are mainly found in the nervous system and/or scattered along the digestive tract. However, recent studies have indicated the notochord, the defining feature of the chordate phylum, as an additional site of expression of insulin-like peptides. Here we show that two of the three insulin-like genes identified in Ciona intestinalis, an invertebrate chordate with a dual life cycle, are first expressed in the developing notochord during embryogenesis and transition to distinct areas of the adult digestive tract after metamorphosis. In addition, we present data suggesting that the transcription factor Ciona Brachyury is involved in the control of notochord expression of at least one of these genes, Ciona insulin-like 2. Finally, we review the information currently available on insulin-producing cells in ascidians and on pancreas-related transcription factors that might control their expression.
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Affiliation(s)
- Jordan M Thompson
- Department of Cell and Developmental Biology, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York
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32
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Brun PJ, Grijalva A, Rausch R, Watson E, Yuen JJ, Das BC, Shudo K, Kagechika H, Leibel RL, Blaner WS. Retinoic acid receptor signaling is required to maintain glucose-stimulated insulin secretion and β-cell mass. FASEB J 2014; 29:671-83. [PMID: 25389133 DOI: 10.1096/fj.14-256743] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Retinoic acid signaling is required for maintaining a range of cellular processes, including cell differentiation, proliferation, and apoptosis. We investigated the actions of all-trans-retinoic acid (atRA) signaling in pancreatic β-cells of adult mice. atRA signaling was ablated in β-cells by overexpressing a dominant-negative retinoic acid receptor (RAR)-α mutant (RARdn) using an inducible Cre-Lox system under the control of the pancreas duodenal homeobox gene promoter. Our studies establish that hypomorphism for RAR in β-cells leads to an age-dependent decrease in plasma insulin in the fed state and in response to a glucose challenge. Glucose-stimulated insulin secretion was also impaired in islets isolated from mice expressing RARdn. Among genes that are atRA responsive, Glut2 and Gck mRNA levels were decreased in isolated islets from RARdn-expressing mice. Histologic analyses of RARdn-expressing pancreata revealed a decrease in β-cell mass and insulin per β-cell 1 mo after induction of the RARdn. Our results indicate that atRA signaling mediated by RARs is required in the adult pancreas for maintaining both β-cell function and mass, and provide insights into molecular mechanisms underlying these actions.
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Affiliation(s)
- Pierre-Jacques Brun
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ambar Grijalva
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Richard Rausch
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Elizabeth Watson
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Jason J Yuen
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Bhaskar C Das
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Koichi Shudo
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroyuki Kagechika
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Rudolph L Leibel
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - William S Blaner
- Departments of *Medicine and Pediatrics and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY USA; Department of Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; Research Foundation Itsuu Laboratory, Tokyo, Japan; and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
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Zhao Y, Flandin P, Vogt D, Blood A, Hermesz E, Westphal H, Rubenstein JLR. Ldb1 is essential for development of Nkx2.1 lineage derived GABAergic and cholinergic neurons in the telencephalon. Dev Biol 2013; 385:94-106. [PMID: 24157949 DOI: 10.1016/j.ydbio.2013.10.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 10/08/2013] [Accepted: 10/09/2013] [Indexed: 11/30/2022]
Abstract
The progenitor zones of the embryonic mouse ventral telencephalon give rise to GABAergic and cholinergic neurons. We have shown previously that two LIM-homeodomain (LIM-HD) transcription factors, Lhx6 and Lhx8, that are downstream of Nkx2.1, are critical for the development of telencephalic GABAergic and cholinergic neurons. Here we investigate the role of Ldb1, a nuclear protein that binds directly to all LIM-HD factors, in the development of these ventral telencephalon derived neurons. We show that Ldb1 is expressed in the Nkx2.1 cell lineage during embryonic development and in mature neurons. Conditional deletion of Ldb1 causes defects in the expression of a series of genes in the ventral telencephalon and severe impairment in the tangential migration of cortical interneurons from the ventral telencephalon. Similar to the phenotypes observed in Lhx6 or Lhx8 mutant mice, the Ldb1 conditional mutants show a reduction in the number of both GABAergic and cholinergic neurons in the telencephalon. Furthermore, our analysis reveals defects in the development of the parvalbumin-positive neurons in the globus pallidus and striatum of the Ldb1 mutants. These results provide evidence that Ldb1 plays an essential role as a transcription co-regulator of Lhx6 and Lhx8 in the control of mammalian telencephalon development.
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Affiliation(s)
- Yangu Zhao
- Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
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O'Dowd JF, Stocker CJ. Endocrine pancreatic development: impact of obesity and diet. Front Physiol 2013; 4:170. [PMID: 23882220 PMCID: PMC3714448 DOI: 10.3389/fphys.2013.00170] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/18/2013] [Indexed: 12/16/2022] Open
Abstract
During embryonic development, multipotent endodermal cells differentiate to form the pancreas. Islet cell clusters arising from the pancreatic bud form the acini tissue and exocrine ducts whilst pancreatic islets form around the edges of the clusters. The successive steps of islet differentiation are controlled by a complex network of transcription factors and signals that influence cell differentiation, growth and lineage. A Westernized lifestyle has led to an increased consumption of a high saturated fat diet, and an increase in maternal obesity. The developing fetus is highly sensitive to the intrauterine environment, therefore any alteration in maternal nutrition during gestation and lactation which affects the in-utero environment during the key developmental phases of the pancreas may change the factors controlling β-cell development and β-cell mass. Whilst the molecular mechanisms behind the adaptive programming of β-cells are still poorly understood it is established that changes arising from maternal obesity and/or over-nutrition may affect the ability to maintain fetal β-cell mass resulting in an increased risk of type 2 diabetes in adulthood.
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Affiliation(s)
- Jacqueline F O'Dowd
- Metabolic Diseases Group, Clore Laboratory, University of Buckingham Buckingham, UK
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Arda HE, Benitez CM, Kim SK. Gene regulatory networks governing pancreas development. Dev Cell 2013; 25:5-13. [PMID: 23597482 DOI: 10.1016/j.devcel.2013.03.016] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 12/13/2022]
Abstract
Elucidation of cellular and gene regulatory networks (GRNs) governing organ development will accelerate progress toward tissue replacement. Here, we have compiled reference GRNs underlying pancreas development from data mining that integrates multiple approaches, including mutant analysis, lineage tracing, cell purification, gene expression and enhancer analysis, and biochemical studies of gene regulation. Using established computational tools, we integrated and represented these networks in frameworks that should enhance understanding of the surging output of genomic-scale genetic and epigenetic studies of pancreas development and diseases such as diabetes and pancreatic cancer. We envision similar approaches would be useful for understanding the development of other organs.
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Affiliation(s)
- H Efsun Arda
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305-5329, USA
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36
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Wilfinger A, Arkhipova V, Meyer D. Cell type and tissue specific function of islet genes in zebrafish pancreas development. Dev Biol 2013; 378:25-37. [PMID: 23518338 PMCID: PMC3657195 DOI: 10.1016/j.ydbio.2013.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 02/06/2013] [Accepted: 03/11/2013] [Indexed: 12/21/2022]
Abstract
Isl1 is a LIM homeobox transcription factor showing conserved expression in the developing and mature vertebrate pancreas. So far, functions of pancreatic Isl1 have mainly been studied in the mouse, where Isl1 has independent functions during formation of exocrine and endocrine tissues. Here, we take advantage of a recently described isl1 mutation in zebrafish to address pancreatic isl1 functions in a non-mammalian system. Isl1 in zebrafish, as in mouse, shows transient expression in mesenchyme flanking the pancreatic endoderm, and continuous expression in all endocrine cells. In isl1 mutants, endocrine cells are specified in normal numbers but more than half of these cells fail to establish expression of endocrine hormones. By using a lineage tracking approach that highlights cells leaving cell cycle early in development, we show that isl1 functions are different in first and second wave endocrine cells. In isl1 mutants, early forming first wave cells show virtually no glucagon expression and a reduced number of cells expressing insulin and somatostatin, while in the later born second wave cells somatostatin expressing cells are strongly reduced and insulin and glucagon positive cells form in normal numbers. Isl1 mutant zebrafish also display a smaller exocrine pancreas. We find that isl1 expression in the pancreatic mesenchyme overlaps with that of the related genes isl2a and isl2b and that pancreatic expression of isl-genes is independent of each other. As a combined block of two or three isl1/2 genes results in a dose-dependent reduction of exocrine tissue, our data suggest that all three genes cooperatively contribute to non-cell autonomous exocrine pancreas extension. The normal expression of the pancreas mesenchyme markers meis3, fgf10 and fgf24 in isl1/2 depleted embryos suggests that this activity is independent of isl-gene function in pancreatic mesenchyme formation as was found in mouse. This indicates species-specific differences in the requirement for isl-genes in pancreatic mesenchyme formation. Overall, our data reveal a novel interaction of isl1 and isl2 genes in exocrine pancreas expansion and cell type specific requirements during endocrine cell maturation. • Overlapping functions of islet1, islet2a and islet2b in exocrine pancreas formation. • Islet1/2a/2b are not required for pancreatic mesenchyme formation. • Islet1 but not islet2a/b is required for endocrine cell maturation. • Endocrine cell types are differently affected by the loss of islet1.
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Affiliation(s)
- Armin Wilfinger
- Institute for Molecular Biology/ CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
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