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Mi J, Ren L, Andersson O. Leveraging zebrafish to investigate pancreatic development, regeneration, and diabetes. Trends Mol Med 2024:S1471-4914(24)00124-2. [PMID: 38825440 DOI: 10.1016/j.molmed.2024.05.002] [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: 01/31/2024] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 06/04/2024]
Abstract
The zebrafish has become an outstanding model for studying organ development and tissue regeneration, which is prominently leveraged for studies of pancreatic development, insulin-producing β-cells, and diabetes. Although studied for more than two decades, many aspects remain elusive and it has only recently been possible to investigate these due to technical advances in transcriptomics, chemical-genetics, genome editing, drug screening, and in vivo imaging. Here, we review recent findings on zebrafish pancreas development, β-cell regeneration, and how zebrafish can be used to provide novel insights into gene functions, disease mechanisms, and therapeutic targets in diabetes, inspiring further use of zebrafish for the development of novel therapies for diabetes.
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Affiliation(s)
- Jiarui Mi
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden; Department of Gastroenterology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China.
| | - Lipeng Ren
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden; Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Uppsala, Sweden
| | - Olov Andersson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden; Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Uppsala, Sweden.
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2
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Tucker TR, Knitter CA, Khoury DM, Eshghi S, Tran S, Sharrock AV, Wiles TJ, Ackerley DF, Mumm JS, Parsons MJ. An inducible model of chronic hyperglycemia. Dis Model Mech 2023; 16:dmm050215. [PMID: 37401381 PMCID: PMC10417516 DOI: 10.1242/dmm.050215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 06/28/2023] [Indexed: 07/05/2023] Open
Abstract
Transgene driven expression of Escherichia coli nitroreductase (NTR1.0) renders animal cells susceptible to the antibiotic metronidazole (MTZ). Many NTR1.0/MTZ ablation tools have been reported in zebrafish, which have significantly impacted regeneration studies. However, NTR1.0-based tools are not appropriate for modeling chronic cell loss as prolonged application of the required MTZ dose (10 mM) is deleterious to zebrafish health. We established that this dose corresponds to the median lethal dose (LD50) of MTZ in larval and adult zebrafish and that it induced intestinal pathology. NTR2.0 is a more active nitroreductase engineered from Vibrio vulnificus NfsB that requires substantially less MTZ to induce cell ablation. Here, we report on the generation of two new NTR2.0-based zebrafish lines in which acute β-cell ablation can be achieved without MTZ-associated intestinal pathology. For the first time, we were able to sustain β-cell loss and maintain elevated glucose levels (chronic hyperglycemia) in larvae and adults. Adult fish showed significant weight loss, consistent with the induction of a diabetic state, indicating that this paradigm will allow the modeling of diabetes and associated pathologies.
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Affiliation(s)
- Tori R. Tucker
- Department of Developmental and Cell Biology, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - Courtney A. Knitter
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - Deena M. Khoury
- Department of Developmental and Cell Biology, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - Sheida Eshghi
- Department of Developmental and Cell Biology, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - Sophia Tran
- Department of Developmental and Cell Biology, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - Abigail V. Sharrock
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Travis J. Wiles
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
| | - David F. Ackerley
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Jeff S. Mumm
- Department of Ophthalmology, The Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Michael J. Parsons
- Department of Developmental and Cell Biology, University of California, Irvine, Natural Sciences II, Irvine, CA 92697, USA
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3
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Faraj N, Duinkerken BHP, Carroll EC, Giepmans BNG. Microscopic modulation and analysis of islets of Langerhans in living zebrafish larvae. FEBS Lett 2022; 596:2497-2512. [DOI: 10.1002/1873-3468.14411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/22/2022] [Accepted: 05/20/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Noura Faraj
- Department of Biomedical Sciences of Cells and Systems, University of Groningen University Medical Center Groningen Groningen 9713AV The Netherlands
| | - B. H. Peter Duinkerken
- Department of Biomedical Sciences of Cells and Systems, University of Groningen University Medical Center Groningen Groningen 9713AV The Netherlands
| | - Elizabeth C. Carroll
- Department of Imaging Physics Delft University of Technology Delft, 2628 CJ The Netherlands
| | - Ben N. G. Giepmans
- Department of Biomedical Sciences of Cells and Systems, University of Groningen University Medical Center Groningen Groningen 9713AV The Netherlands
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4
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Figiel DM, Elsayed R, Nelson AC. Investigating the molecular guts of endoderm formation using zebrafish. Brief Funct Genomics 2021:elab013. [PMID: 33754635 DOI: 10.1093/bfgp/elab013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/27/2021] [Accepted: 02/19/2021] [Indexed: 02/07/2023] Open
Abstract
The vertebrate endoderm makes major contributions to the respiratory and gastrointestinal tracts and all associated organs. Zebrafish and humans share a high degree of genetic homology and strikingly similar endodermal organ systems. Combined with a multitude of experimental advantages, zebrafish are an attractive model organism to study endoderm development and disease. Recent functional genomics studies have shed considerable light on the gene regulatory programs governing early zebrafish endoderm development, while advances in biological and technological approaches stand to further revolutionize our ability to investigate endoderm formation, function and disease. Here, we discuss the present understanding of endoderm specification in zebrafish compared to other vertebrates, how current and emerging methods will allow refined and enhanced analysis of endoderm formation, and how integration with human data will allow modeling of the link between non-coding sequence variants and human disease.
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Affiliation(s)
- Daniela M Figiel
- Medical Research Council Doctoral Training Partnership in Interdisciplinary Biomedical Research at Warwick Medical School
| | - Randa Elsayed
- Medical Research Council Doctoral Training Partnership in Interdisciplinary Biomedical Research at Warwick Medical School
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5
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De novo loss-of-function variants in X-linked MED12 are associated with Hardikar syndrome in females. Genet Med 2020; 23:637-644. [PMID: 33244166 DOI: 10.1038/s41436-020-01031-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/15/2020] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Hardikar syndrome (MIM 612726) is a rare multiple congenital anomaly syndrome characterized by facial clefting, pigmentary retinopathy, biliary anomalies, and intestinal malrotation, but with preserved cognition. Only four patients have been reported previously, and none had a molecular diagnosis. Our objective was to identify the genetic basis of Hardikar syndrome (HS) and expand the phenotypic spectrum of this disorder. METHODS We performed exome sequencing on two previously reported and five unpublished female patients with a clinical diagnosis of HS. X-chromosome inactivation (XCI) studies were also performed. RESULTS We report clinical features of HS with previously undescribed phenotypes, including a fatal unprovoked intracranial hemorrhage at age 21. We additionally report the discovery of de novo pathogenic nonsense and frameshift variants in MED12 in these seven individuals and evidence of extremely skewed XCI in all patients with informative testing. CONCLUSION Pathogenic missense variants in the X-chromosome gene MED12 have previously been associated with Opitz-Kaveggia syndrome, Lujan syndrome, Ohdo syndrome, and nonsyndromic intellectual disability, primarily in males. We propose a fifth, female-specific phenotype for MED12, and suggest that nonsense and frameshift loss-of-function MED12 variants in females cause HS. This expands the MED12-associated phenotype in females beyond intellectual disability.
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Hernandez-Perez M, Kulkarni A, Samala N, Sorrell C, El K, Haider I, Aleem AM, Holman TR, Rai G, Tersey SA, Mirmira RG, Anderson RM. A 12-lipoxygenase-Gpr31 signaling axis is required for pancreatic organogenesis in the zebrafish. FASEB J 2020; 34:14850-14862. [PMID: 32918516 PMCID: PMC7606739 DOI: 10.1096/fj.201902308rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 12/19/2022]
Abstract
12-Lipoxygenase (12-LOX) is a key enzyme in arachidonic acid metabolism, and alongside its major product, 12-HETE, plays a key role in promoting inflammatory signaling during diabetes pathogenesis. Although 12-LOX is a proposed therapeutic target to protect pancreatic islets in the setting of diabetes, little is known about the consequences of blocking its enzymatic activity during embryonic development. Here, we have leveraged the strengths of the zebrafish-genetic manipulation and pharmacologic inhibition-to interrogate the role of 12-LOX in pancreatic development. Lipidomics analysis during zebrafish development demonstrated that 12-LOX-generated metabolites of arachidonic acid increase sharply during organogenesis stages, and that this increase is blocked by morpholino-directed depletion of 12-LOX. Furthermore, we found that either depletion or inhibition of 12-LOX impairs both exocrine pancreas growth and unexpectedly, the generation of insulin-producing β cells. We demonstrate that morpholino-mediated knockdown of GPR31, a purported G-protein-coupled receptor for 12-HETE, largely phenocopies both the depletion and the inhibition of 12-LOX. Moreover, we show that loss of GPR31 impairs pancreatic bud fusion and pancreatic duct morphogenesis. Together, these data provide new insight into the requirement of 12-LOX in pancreatic organogenesis and islet formation, and additionally provide evidence that its effects are mediated via a signaling axis that includes the 12-HETE receptor GPR31.
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Affiliation(s)
- Marimar Hernandez-Perez
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Abhishek Kulkarni
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Niharika Samala
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cody Sorrell
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kimberly El
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Isra Haider
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ansari Mukhtar Aleem
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Theodore R Holman
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Sarah A Tersey
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Raghavendra G Mirmira
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Kovler Diabetes Center, The University of Chicago, Chicago, IL, USA
| | - Ryan M Anderson
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Kovler Diabetes Center, The University of Chicago, Chicago, IL, USA
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7
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Rubinato E, Rondeau S, Giuliano F, Kossorotoff M, Parodi M, Gherbi S, Steffan J, Jonard L, Marlin S. MED12 missense mutation in a three-generation family. Clinical characterization of MED12-related disorders and literature review. Eur J Med Genet 2020; 63:103768. [DOI: 10.1016/j.ejmg.2019.103768] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 07/23/2019] [Accepted: 09/15/2019] [Indexed: 10/26/2022]
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8
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Helker CSM, Mullapudi ST, Mueller LM, Preussner J, Tunaru S, Skog O, Kwon HB, Kreuder F, Lancman JJ, Bonnavion R, Dong PDS, Looso M, Offermanns S, Korsgren O, Spagnoli FM, Stainier DYR. A whole organism small molecule screen identifies novel regulators of pancreatic endocrine development. Development 2019; 146:dev.172569. [PMID: 31142539 DOI: 10.1242/dev.172569] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 05/08/2019] [Indexed: 12/16/2022]
Abstract
An early step in pancreas development is marked by the expression of the transcription factor Pdx1 within the pancreatic endoderm, where it is required for the specification of all endocrine cell types. Subsequently, Pdx1 expression becomes restricted to the β-cell lineage, where it plays a central role in β-cell function. This pivotal role of Pdx1 at various stages of pancreas development makes it an attractive target to enhance pancreatic β-cell differentiation and increase β-cell function. In this study, we used a newly generated zebrafish reporter to screen over 8000 small molecules for modulators of pdx1 expression. We found four hit compounds and validated their efficacy at different stages of pancreas development. Notably, valproic acid treatment increased pancreatic endoderm formation, while inhibition of TGFβ signaling led to α-cell to β-cell transdifferentiation. HC toxin, another HDAC inhibitor, enhances β-cell function in primary mouse and human islets. Thus, using a whole organism screening strategy, this study identified new pdx1 expression modulators that can be used to influence different steps in pancreas and β-cell development.
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Affiliation(s)
- Christian S M Helker
- Max Planck Institute for Heart and Lung Research, Department of Developmental Genetics, 61231 Bad Nauheim, Germany .,Philipps-University Marburg, Faculty of Biology, Cell Signaling and Dynamics, 35043 Marburg, Germany
| | - Sri-Teja Mullapudi
- Max Planck Institute for Heart and Lung Research, Department of Developmental Genetics, 61231 Bad Nauheim, Germany
| | - Laura M Mueller
- Centre for Stem Cells and Regenerative Medicine, King's College London, London WC2R 2LS, UK
| | - Jens Preussner
- Max Planck Institute for Heart and Lung Research, ECCPS Bioinformatics Core Unit, 61231 Bad Nauheim, Germany
| | - Sorin Tunaru
- Max Planck Institute for Heart and Lung Research, Department of Pharmacology, 61231 Bad Nauheim, Germany.,Biochemistry Institute of the Romanian Academy, Department of Enzymology, Bucharest 060031, Romania
| | - Oskar Skog
- Uppsala University, Department of Immunology, Genetics and Pathology, 751 85 Uppsala, Sweden
| | - Hyouk-Bum Kwon
- Max Planck Institute for Heart and Lung Research, Department of Developmental Genetics, 61231 Bad Nauheim, Germany
| | - Florian Kreuder
- Max Planck Institute for Heart and Lung Research, Department of Developmental Genetics, 61231 Bad Nauheim, Germany
| | - Joseph J Lancman
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.,Graduate School of Biomedical Sciences, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Remy Bonnavion
- Max Planck Institute for Heart and Lung Research, Department of Pharmacology, 61231 Bad Nauheim, Germany
| | - P Duc Si Dong
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.,Graduate School of Biomedical Sciences, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Mario Looso
- Max Planck Institute for Heart and Lung Research, ECCPS Bioinformatics Core Unit, 61231 Bad Nauheim, Germany
| | - Stefan Offermanns
- Max Planck Institute for Heart and Lung Research, Department of Pharmacology, 61231 Bad Nauheim, Germany
| | - Ole Korsgren
- Uppsala University, Department of Immunology, Genetics and Pathology, 751 85 Uppsala, Sweden
| | - Francesca M Spagnoli
- Centre for Stem Cells and Regenerative Medicine, King's College London, London WC2R 2LS, UK
| | - Didier Y R Stainier
- Max Planck Institute for Heart and Lung Research, Department of Developmental Genetics, 61231 Bad Nauheim, Germany
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9
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Srivastava S, Niranjan T, May MM, Tarpey P, Allen W, Hackett A, Jouk P, Raymond L, Briault S, Skinner C, Toutain A, Gecz J, Heath W, Stevenson RE, Schwartz CE, Wang T. Dysregulations of sonic hedgehog signaling in MED12-related X-linked intellectual disability disorders. Mol Genet Genomic Med 2019; 7:e00569. [PMID: 30729724 PMCID: PMC6465656 DOI: 10.1002/mgg3.569] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Mutations in mediator of RNA polymerase II transcription subunit 12 homolog (MED12, OMIM 300188) cause X-linked intellectual disability (XLID) disorders including FG, Lujan, and Ohdo syndromes. The Gli3-dependent Sonic Hedgehog (SHH) signaling pathway has been implicated in the original FG syndrome and Lujan syndrome. How are SHH-signaling defects related to the complex clinical phenotype of MED12-associated XLID syndromes are not fully understood. METHODS Quantitative RT-PCR was used to study expression levels of three SHH-signaling genes in lymophoblast cell lines carrying four MED12 mutations from four unrelated XLID families. Genotype and phenotype correlation studies were performed on these mutations. RESULTS Three newly identified and one novel MED12 mutations in six affected males from four unrelated XLID families were studied. Three mutations (c.2692A>G; p.N898D, c.3640C>T; p.R1214C, and c.3884G>A; p.R1295H) are located in the LS domain and one (c.617G>A; p.R206Q) is in the L domain of MED12. These mutations involve highly conserved amino acid residues and segregate with ID and related congenital malformations in respective probands families. Patients with the LS-domain mutations share many features of FG syndrome and some features of Lujan syndrome. The patient with the L-domain mutation presented with ID and predominant neuropsychiatric features but little dysmorphic features of either FG or Lujan syndrome. Transcript levels of three Gli3-dependent SHH-signaling genes, CREB5, BMP4, and NEUROG2, were determined by quantitative RT-PCR and found to be significantly elevated in lymphoblasts from patients with three mutations in the MED12-LS domain. CONCLUSIONS These results support a critical role of MED12 in regulating Gli3-dependent SHH signaling and in developing ID and related congenital malformations in XLID syndromes. Differences in the expression profile of SHH-signaling genes potentially contribute to variability in clinical phenotypes in patients with MED12-related XLID disorders.
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Affiliation(s)
- Siddharth Srivastava
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
| | - Tejasvi Niranjan
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
| | | | | | | | - Anna Hackett
- Genetics of Learning Disability ServiceHunter GeneticsWaratahNSWAustralia
| | | | - Lucy Raymond
- Cambridge Institute of Medical ResearchCambridgeUK
| | | | | | - Annick Toutain
- Service de Génétique Clinique, Hôpital BretonneauToursFrance
| | - Jozef Gecz
- Adelaide Medical School and Robinson Research InstituteThe University of AdelaideAdelaideAustralia
| | - William Heath
- J.I. Riddle Developmental CenterMorgantonNorth Carolina
| | | | | | - Tao Wang
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
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10
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Nelson AC, Cutty SJ, Gasiunas SN, Deplae I, Stemple DL, Wardle FC. In Vivo Regulation of the Zebrafish Endoderm Progenitor Niche by T-Box Transcription Factors. Cell Rep 2018; 19:2782-2795. [PMID: 28658625 PMCID: PMC5494305 DOI: 10.1016/j.celrep.2017.06.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 04/28/2017] [Accepted: 05/31/2017] [Indexed: 01/15/2023] Open
Abstract
T-box transcription factors T/Brachyury homolog A (Ta) and Tbx16 are essential for correct mesoderm development in zebrafish. The downstream transcriptional networks guiding their functional activities are poorly understood. Additionally, important contributions elsewhere are likely masked due to redundancy. Here, we exploit functional genomic strategies to identify Ta and Tbx16 targets in early embryogenesis. Surprisingly, we discovered they not only activate mesodermal gene expression but also redundantly regulate key endodermal determinants, leading to substantial loss of endoderm in double mutants. To further explore the gene regulatory networks (GRNs) governing endoderm formation, we identified targets of Ta/Tbx16-regulated homeodomain transcription factor Mixl1, which is absolutely required in zebrafish for endoderm formation. Interestingly, we find many endodermal determinants coordinately regulated through common genomic occupancy by Mixl1, Eomesa, Smad2, Nanog, Mxtx2, and Pou5f3. Collectively, these findings augment the endoderm GRN and reveal a panel of target genes underlying the Ta, Tbx16, and Mixl1 mutant phenotypes.
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Affiliation(s)
- Andrew C Nelson
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK; School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
| | - Stephen J Cutty
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Saule N Gasiunas
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Isabella Deplae
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Derek L Stemple
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Fiona C Wardle
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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11
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Baskin KK, Makarewich CA, DeLeon SM, Ye W, Chen B, Beetz N, Schrewe H, Bassel-Duby R, Olson EN. MED12 regulates a transcriptional network of calcium-handling genes in the heart. JCI Insight 2017; 2:91920. [PMID: 28724790 DOI: 10.1172/jci.insight.91920] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 06/13/2017] [Indexed: 02/06/2023] Open
Abstract
The Mediator complex regulates gene transcription by linking basal transcriptional machinery with DNA-bound transcription factors. The activity of the Mediator complex is mainly controlled by a kinase submodule that is composed of 4 proteins, including MED12. Although ubiquitously expressed, Mediator subunits can differentially regulate gene expression in a tissue-specific manner. Here, we report that MED12 is required for normal cardiac function, such that mice with conditional cardiac-specific deletion of MED12 display progressive dilated cardiomyopathy. Loss of MED12 perturbs expression of calcium-handling genes in the heart, consequently altering calcium cycling in cardiomyocytes and disrupting cardiac electrical activity. We identified transcription factors that regulate expression of calcium-handling genes that are downregulated in the heart in the absence of MED12, and we found that MED12 localizes to transcription factor consensus sequences within calcium-handling genes. We showed that MED12 interacts with one such transcription factor, MEF2, in cardiomyocytes and that MED12 and MEF2 co-occupy promoters of calcium-handling genes. Furthermore, we demonstrated that MED12 enhances MEF2 transcriptional activity and that overexpression of both increases expression of calcium-handling genes in cardiomyocytes. Our data support a role for MED12 as a coordinator of transcription through MEF2 and other transcription factors. We conclude that MED12 is a regulator of a network of calcium-handling genes, consequently mediating contractility in the mammalian heart.
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Affiliation(s)
| | | | | | | | - Beibei Chen
- Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | - Heinrich Schrewe
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Rhonda Bassel-Duby
- Department of Molecular Biology and.,Hamon Center for Regenerative Science and Medicine and.,Sen. Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Eric N Olson
- Department of Molecular Biology and.,Hamon Center for Regenerative Science and Medicine and.,Sen. Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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12
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Luo S, Horvitz HR. The CDK8 Complex and Proneural Proteins Together Drive Neurogenesis from a Mesodermal Lineage. Curr Biol 2017; 27:661-672. [PMID: 28238659 DOI: 10.1016/j.cub.2017.01.056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/08/2016] [Accepted: 01/26/2017] [Indexed: 11/25/2022]
Abstract
At least some animal species can generate neurons from mesoderm or endoderm, but the underlying mechanisms remain unknown. We screened for C. elegans mutants in which the presumptive mesoderm-derived I4 neuron adopts a muscle-like cell fate. From this screen, we identified HLH-3, the C. elegans homolog of a mammalian proneural protein (Ascl1) used for in vitro neuronal reprogramming, as required for efficient I4 neurogenesis. We discovered that the CDK-8 Mediator kinase module acts together with a second proneural protein, HLH-2, and in parallel to HLH-3 to promote I4 neurogenesis. Genetic analysis revealed that CDK-8 most likely promotes I4 neurogenesis by inhibiting the CDK-7/CYH-1 (CDK7/cyclin H) kinase module of the transcription initiation factor TFIIH. Ectopic expression of HLH-2 and HLH-3 together promoted expression of neuronal features in non-neuronal cells. These findings reveal that the Mediator CDK8 kinase module can promote non-ectodermal neurogenesis and suggest that inhibiting CDK7/cyclin H might similarly promote neurogenesis.
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Affiliation(s)
- Shuo Luo
- Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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13
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Keightley MC, Nilsson SK, Lieschke GJ. MED12 in hematopoietic stem cells-cell specific function despite ubiquitous expression. Stem Cell Investig 2017; 4:3. [PMID: 28217705 DOI: 10.21037/sci.2016.12.04] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 12/08/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Maria-Cristina Keightley
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Susan K Nilsson
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia;; CSIRO Manufacturing, Clayton, Victoria 3800, Australia
| | - Graham J Lieschke
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
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14
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Villasenor A, Stainier DYR. On the development of the hepatopancreatic ductal system. Semin Cell Dev Biol 2017; 66:69-80. [PMID: 28214561 DOI: 10.1016/j.semcdb.2017.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/03/2017] [Accepted: 02/13/2017] [Indexed: 12/13/2022]
Abstract
The hepatopancreatic ductal system is the collection of ducts that connect the liver and pancreas to the digestive tract. The formation of this system is necessary for the transport of exocrine secretions, for the correct assembly of the pancreatobiliary ductal system, and for the overall function of the digestive system. Studies on endoderm organ formation have significantly advanced our understanding of the molecular mechanisms that govern organ induction, organ specification and morphogenesis of the major foregut-derived organs. However, little is known about the mechanisms that control the development of the hepatopancreatic ductal system. Here, we provide a description of the different components of the system, summarize its development from the endoderm to a complex system of tubes, list the pathologies produced by anomalies in its development, as well as the molecules and signaling pathways that are known to be involved in its formation. Finally, we discuss its proposed potential as a multipotent cell reservoir and the unresolved questions in the field.
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Affiliation(s)
- Alethia Villasenor
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
| | - Didier Y R Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
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15
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Abstract
The zebrafish pancreas shares its basic organization and cell types with the mammalian pancreas. In addition, the developmental pathways that lead to the establishment of the pancreatic islets of Langherhans are generally conserved from fish to mammals. Zebrafish provides a powerful tool to probe the mechanisms controlling establishment of the pancreatic endocrine cell types from early embryonic progenitor cells, as well as the regeneration of endocrine cells after damage. This knowledge is, in turn, applicable to refining protocols to generate renewable sources of human pancreatic islet cells that are critical for regulation of blood sugar levels. Here, we review how previous and ongoing studies in zebrafish and beyond are influencing the understanding of molecular mechanisms underlying various forms of diabetes and efforts to develop cell-based approaches to cure this increasingly widespread disease.
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16
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Clark AD, Oldenbroek M, Boyer TG. Mediator kinase module and human tumorigenesis. Crit Rev Biochem Mol Biol 2015; 50:393-426. [PMID: 26182352 DOI: 10.3109/10409238.2015.1064854] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mediator is a conserved multi-subunit signal processor through which regulatory informatiosn conveyed by gene-specific transcription factors is transduced to RNA Polymerase II (Pol II). In humans, MED13, MED12, CDK8 and Cyclin C (CycC) comprise a four-subunit "kinase" module that exists in variable association with a 26-subunit Mediator core. Genetic and biochemical studies have established the Mediator kinase module as a major ingress of developmental and oncogenic signaling through Mediator, and much of its function in signal-dependent gene regulation derives from its resident CDK8 kinase activity. For example, CDK8-targeted substrate phosphorylation impacts transcription factor half-life, Pol II activity and chromatin chemistry and functional status. Recent structural and biochemical studies have revealed a precise network of physical and functional subunit interactions required for proper kinase module activity. Accordingly, pathologic change in this activity through altered expression or mutation of constituent kinase module subunits can have profound consequences for altered signaling and tumor formation. Herein, we review the structural organization, biological function and oncogenic potential of the Mediator kinase module. We focus principally on tumor-associated alterations in kinase module subunits for which mechanistic relationships as opposed to strictly correlative associations are established. These considerations point to an emerging picture of the Mediator kinase module as an oncogenic unit, one in which pathogenic activation/deactivation through component change drives tumor formation through perturbation of signal-dependent gene regulation. It follows that therapeutic strategies to combat CDK8-driven tumors will involve targeted modulation of CDK8 activity or pharmacologic manipulation of dysregulated CDK8-dependent signaling pathways.
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Affiliation(s)
- Alison D Clark
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Marieke Oldenbroek
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Thomas G Boyer
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
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17
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Bouazzi H, Lesca G, Trujillo C, Alwasiyah MK, Munnich A. Nonsyndromic X-linked intellectual deficiency in three brothers with a novel MED12 missense mutation [c.5922G>T (p.Glu1974His)]. Clin Case Rep 2015; 3:604-9. [PMID: 26273451 PMCID: PMC4527805 DOI: 10.1002/ccr3.301] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 04/27/2015] [Indexed: 12/23/2022] Open
Abstract
X-linked intellectual deficiency (XLID) is a large group of genetic disorders. MED12 gene causes syndromic and nonsyndromic forms of XLID. Only seven pathological mutations have been identified in this gene. Here, we report a novel mutation segregating with XLID phenotype. This mutation could be in favor of genotype-phenotype correlations.
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Affiliation(s)
- Habib Bouazzi
- Hôpital Necker - Enfants Malades INSERM U781, Laboratoire de génétique médicale. Tour Lavoisier - 3 étage149 rue de Sèvres – 75743, Paris Cedex 15, France
| | - Gaetan Lesca
- Service de Cytogénétique constitutionnelle, Groupement Hospitalier Est.59 Boulevard Pinel, 69677, Bron Cedex, France
| | - Carlos Trujillo
- Genetics Unit, Erfan & Bagedo HospitalP.O. Box 6519, Jeddah, 21452, Saudi Arabia
| | | | - Arnold Munnich
- Hôpital Necker - Enfants Malades, Unité INSERM 781, Laboratoire de génétique moléculaireTour Lavoisier - 2ème étage, 149 rue de Sèvres – 75743, Paris Cedex 15, France
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18
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Hunter JM, Kiefer J, Balak CD, Jooma S, Ahearn ME, Hall JG, Baumbach-Reardon L. Review of X-linked syndromes with arthrogryposis or early contractures-aid to diagnosis and pathway identification. Am J Med Genet A 2015; 167A:931-73. [DOI: 10.1002/ajmg.a.36934] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/05/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Jesse M. Hunter
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Jeff Kiefer
- Knowledge Mining; Translational Genomics Research Institute; Phoenix Arizona
| | - Christopher D. Balak
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Sonya Jooma
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Mary Ellen Ahearn
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
| | - Judith G. Hall
- Departments of Medical Genetics and Pediatrics; University of British Columbia and BC Children's Hospital Vancouver; British Columbia Canada
| | - Lisa Baumbach-Reardon
- Integrated Functional Cancer Genomics; Translational Genomics Research Institute; Phoenix Arizona
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19
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Muto A, Ikeda S, Lopez-Burks ME, Kikuchi Y, Calof AL, Lander AD, Schilling TF. Nipbl and mediator cooperatively regulate gene expression to control limb development. PLoS Genet 2014; 10:e1004671. [PMID: 25255084 PMCID: PMC4177752 DOI: 10.1371/journal.pgen.1004671] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 08/14/2014] [Indexed: 11/19/2022] Open
Abstract
Haploinsufficiency for Nipbl, a cohesin loading protein, causes Cornelia de Lange Syndrome (CdLS), the most common “cohesinopathy”. It has been proposed that the effects of Nipbl-haploinsufficiency result from disruption of long-range communication between DNA elements. Here we use zebrafish and mouse models of CdLS to examine how transcriptional changes caused by Nipbl deficiency give rise to limb defects, a common condition in individuals with CdLS. In the zebrafish pectoral fin (forelimb), knockdown of Nipbl expression led to size reductions and patterning defects that were preceded by dysregulated expression of key early limb development genes, including fgfs, shha, hand2 and multiple hox genes. In limb buds of Nipbl-haploinsufficient mice, transcriptome analysis revealed many similar gene expression changes, as well as altered expression of additional classes of genes that play roles in limb development. In both species, the pattern of dysregulation of hox-gene expression depended on genomic location within the Hox clusters. In view of studies suggesting that Nipbl colocalizes with the mediator complex, which facilitates enhancer-promoter communication, we also examined zebrafish deficient for the Med12 Mediator subunit, and found they resembled Nipbl-deficient fish in both morphology and gene expression. Moreover, combined partial reduction of both Nipbl and Med12 had a strongly synergistic effect, consistent with both molecules acting in a common pathway. In addition, three-dimensional fluorescent in situ hybridization revealed that Nipbl and Med12 are required to bring regions containing long-range enhancers into close proximity with the zebrafish hoxda cluster. These data demonstrate a crucial role for Nipbl in limb development, and support the view that its actions on multiple gene pathways result from its influence, together with Mediator, on regulation of long-range chromosomal interactions. Limb malformations are a striking feature of Cornelia de Lange Syndrome (CdLS), a multi-system birth defects disorder most commonly caused by haploinsufficiency for NIPBL. In addition to its role as a cohesin-loading factor, Nipbl also regulates gene expression, but how partial Nipbl deficiency causes limb defects is unknown. Using zebrafish and mouse models, we show that expression of multiple key regulators of early limb development, including shha, hand2 and hox genes, are sensitive to Nipbl deficiency. Furthermore, we find morphological and gene expression abnormalities similar to those of Nipbl-deficient zebrafish in the limb buds of zebrafish deficient for the Med12 subunit of Mediator—a protein complex that mediates physical interactions between enhancers and promoters—and genetic interaction studies support the view that Mediator and Nipbl act together. Strikingly, depletion of either Nipbl or Med12 leads to characteristic changes in hox gene expression that reflect the locations of genes within their chromosomal clusters, as well as to disruption of large-scale chromosome organization around the hoxda cluster, consistent with impairment of long-range enhancer-promoter interaction. Together, these findings provide insights into both the etiology of limb defects in CdLS, and the mechanisms by which Nipbl and Mediator influence gene expression.
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Affiliation(s)
- Akihiko Muto
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine California
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Shingo Ikeda
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Martha E. Lopez-Burks
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine California
| | - Yutaka Kikuchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Anne L. Calof
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- Department of Anatomy & Neurobiology, University of California, Irvine, Irvine, California, United States of America
- * E-mail: (ALC); (ADL)
| | - Arthur D. Lander
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine California
- * E-mail: (ALC); (ADL)
| | - Thomas F. Schilling
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine California
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20
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RNA-Seq for the identification of novel Mediator transcripts in endothelial progenitor cells. Gene 2014; 547:98-105. [PMID: 24952135 DOI: 10.1016/j.gene.2014.06.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 05/30/2014] [Accepted: 06/17/2014] [Indexed: 11/22/2022]
Abstract
Mediator (MED) complex is a multiprotein playing a key role in the eukaryotic transcription. Alteration of MED function may have enormous pathophysiological consequences and several MED genes have been implicated in human diseases. Here, we have combined computational and experimental approaches to identify and characterize, new transcripts generated by alternative splicing (AS) for all MED genes, through the analysis of our recently published RNA-Sequencing datasets of endothelial progenitor cells (EPCs). This combined strategy allowed us to identify novel transcripts for MED4, MED9, MED11, MED14, MED27 and CDK8 most of them generated by AS. All the newly identified transcripts, except MED11, are predicted to encode novel protein isoforms. The identification of novel MED variants could lead to the finding of other MED complexes with different functions depending on their subunit composition. Finally, the expression profile of all MED genes, together with an extensive gene expression analysis, may be useful to better classify the diverse subsets of cell populations that contribute to neovascularization.
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21
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Yin JW, Wang G. The Mediator complex: a master coordinator of transcription and cell lineage development. Development 2014; 141:977-87. [PMID: 24550107 DOI: 10.1242/dev.098392] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mediator is a multiprotein complex that is required for gene transcription by RNA polymerase II. Multiple subunits of the complex show specificity in relaying information from signals and transcription factors to the RNA polymerase II machinery, thus enabling control of the expression of specific genes. Recent studies have also provided novel mechanistic insights into the roles of Mediator in epigenetic regulation, transcriptional elongation, termination, mRNA processing, noncoding RNA activation and super enhancer formation. Based on these specific roles in gene regulation, Mediator has emerged as a master coordinator of development and cell lineage determination. Here, we describe the most recent advances in understanding the mechanisms of Mediator function, with an emphasis on its role during development and disease.
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Affiliation(s)
- Jing-wen Yin
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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22
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Wu SY, de Borsetti NH, Bain EJ, Bulow CR, Gamse JT. Mediator subunit 12 coordinates intrinsic and extrinsic control of epithalamic development. Dev Biol 2014; 385:13-22. [DOI: 10.1016/j.ydbio.2013.10.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/01/2013] [Accepted: 10/23/2013] [Indexed: 12/22/2022]
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23
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Hepatocyte growth factor signaling in intrapancreatic ductal cells drives pancreatic morphogenesis. PLoS Genet 2013; 9:e1003650. [PMID: 23935514 PMCID: PMC3723531 DOI: 10.1371/journal.pgen.1003650] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 06/04/2013] [Indexed: 12/17/2022] Open
Abstract
In a forward genetic screen for regulators of pancreas development in zebrafish, we identified donut(s908) , a mutant which exhibits failed outgrowth of the exocrine pancreas. The s908 mutation leads to a leucine to arginine substitution in the ectodomain of the hepatocyte growth factor (HGF) tyrosine kinase receptor, Met. This missense mutation impedes the proteolytic maturation of the receptor, its trafficking to the plasma membrane, and diminishes the phospho-activation of its kinase domain. Interestingly, during pancreatogenesis, met and its hgf ligands are expressed in pancreatic epithelia and mesenchyme, respectively. Although Met signaling elicits mitogenic and migratory responses in varied contexts, normal proliferation rates in donut mutant pancreata together with dysmorphic, mislocalized ductal cells suggest that met primarily functions motogenically in pancreatic tail formation. Treatment with PI3K and STAT3 inhibitors, but not with MAPK inhibitors, phenocopies the donut pancreatic defect, further indicating that Met signals through migratory pathways during pancreas development. Chimera analyses showed that Met-deficient cells were excluded from the duct, but not acinar, compartment in the pancreatic tail. Conversely, wild-type intrapancreatic duct and "tip cells" at the leading edge of the growing pancreas rescued the donut phenotype. Altogether, these results reveal a novel and essential role for HGF signaling in the intrapancreatic ducts during exocrine morphogenesis.
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24
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Sox10 cooperates with the mediator subunit 12 during terminal differentiation of myelinating glia. J Neurosci 2013; 33:6679-90. [PMID: 23575864 DOI: 10.1523/jneurosci.5178-12.2013] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Several transcription factors are essential for terminal differentiation of myelinating glia, among them the high-mobility-group-domain-containing protein Sox10. To better understand how these factors exert their effects and shape glial expression programs, we identified and characterized a physical and functional link between Sox10 and the Med12 subunit of the Mediator complex that serves as a conserved multiprotein interphase between transcription factors and the general transcription machinery. We found that Sox10 bound with two of its conserved domains to the C-terminal region of Med12 and its close relative, Med12-like. In contrast to Med12-like, substantial amounts of Med12 were detected in both Schwann cells and oligodendrocytes. Its conditional glia-specific deletion in mice led to terminal differentiation defects that were highly reminiscent of those obtained after Sox10 deletion. In support of a functional cooperation, both proteins were jointly required for Krox20 induction and were physically associated with the critical regulatory region of the Krox20 gene in myelinating Schwann cells. We conclude that Sox10 functions during terminal differentiation of myelinating glia, at least in part by Med12-dependent recruitment of the Mediator complex.
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25
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Steimel A, Suh J, Hussainkhel A, Deheshi S, Grants JM, Zapf R, Moerman DG, Taubert S, Hutter H. The C. elegans CDK8 Mediator module regulates axon guidance decisions in the ventral nerve cord and during dorsal axon navigation. Dev Biol 2013; 377:385-98. [PMID: 23458898 DOI: 10.1016/j.ydbio.2013.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 01/21/2013] [Accepted: 02/14/2013] [Indexed: 11/30/2022]
Abstract
Receptors expressed on the growth cone of outgrowing axons detect cues required for proper navigation. The pathway choices available to an axon are in part defined by the set of guidance receptors present on the growth cone. Regulated expression of receptors and genes controlling the localization and activity of receptors ensures that axons respond only to guidance cues relevant for reaching their targets. In genetic screens for axon guidance mutants, we isolated an allele of let-19/mdt-13, a component of the Mediator, a large ~30 subunit protein complex essential for gene transcription by RNA polymerase II. LET-19/MDT-13 is part of the CDK8 module of the Mediator. By testing other Mediator components, we found that all subunits of the CDK8 module as well as some other Mediator components are required for specific axon navigation decisions in a subset of neurons. Expression profiling demonstrated that let-19/mdt-13 regulates the expression of a large number of genes in interneurons. A mutation in the sax-3 gene, encoding a receptor for the repulsive guidance cue SLT-1, suppresses the commissure navigation defects found in cdk-8 mutants. This suggests that the CDK8 module specifically represses the SAX-3/ROBO pathway to ensure proper commissure navigation.
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Affiliation(s)
- Andreas Steimel
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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26
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Arkhipova V, Wendik B, Devos N, Ek O, Peers B, Meyer D. Characterization and regulation of the hb9/mnx1 beta-cell progenitor specific enhancer in zebrafish. Dev Biol 2012; 365:290-302. [PMID: 22426004 PMCID: PMC3327876 DOI: 10.1016/j.ydbio.2012.03.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 02/27/2012] [Accepted: 03/01/2012] [Indexed: 11/06/2022]
Abstract
Differentiation of insulin producing beta-cells is a genetically well defined process that involves functions of various conserved transcription factors. Still, the transcriptional mechanisms underlying specification and determination of beta-cell fate are poorly defined. Here we provide the description of a beta-cell progenitor specific enhancer as a model to study initial steps of beta-cell differentiation. We show that evolutionary non-conserved upstream sequences of the zebrafish hb9 gene are required and sufficient for regulating expression in beta-cells prior to the onset of insulin expression. This enhancer contains binding sites for paired-box transcription factors and two E-boxes that in EMSA studies show interaction with Pax6b and NeuroD, respectively. We show that Pax6b is a potent activator of endodermal hb9 expression and that this activation depends on the beta-cell enhancer. Using genetic approaches we show that pax6b is crucial for maintenance but not induction of pancreatic hb9 transcription. As loss of Pax6b or Hb9 independently results in the loss of insulin expression, the data reveal a novel cross-talk between the two essential regulators of early beta-cell differentiation. While we find that the known pancreatic E-box binding proteins NeuroD and Ngn3 are not required for hb9 expression we also show that removal of both E-boxes selectively eliminates pancreatic specific reporter expression. The data provide evidence for an Ngn3 independent pathway of beta-cell specification that requires function of currently not specified E-box binding factors.
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Affiliation(s)
- Valeriya Arkhipova
- Institute for Molecular Biology/CMBI, Technikerstr. 25, University of Innsbruck, 6020 Innsbruck, Austria.
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27
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Mo W, Nicolson T. Both pre- and postsynaptic activity of Nsf prevents degeneration of hair-cell synapses. PLoS One 2011; 6:e27146. [PMID: 22073277 PMCID: PMC3207842 DOI: 10.1371/journal.pone.0027146] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 10/11/2011] [Indexed: 01/27/2023] Open
Abstract
Vesicle fusion contributes to the maintenance of synapses in the nervous system by mediating synaptic transmission, release of neurotrophic factors, and trafficking of membrane receptors. N-ethylmaleimide-sensitive factor (NSF) is indispensible for dissociation of the SNARE-complex following vesicle fusion. Although NSF function has been characterized extensively in vitro, the in vivo role of NSF in vertebrate synaptogenesis is relatively unexplored. Zebrafish possess two nsf genes, nsf and nsfb. Here, we examine the function of either Nsf or Nsfb in the pre- and postsynaptic cells of the zebrafish lateral line organ and demonstrate that Nsf, but not Nsfb, is required for maintenance of afferent synapses in hair cells. In addition to peripheral defects in nsf mutants, neurodegeneration of glutamatergic synapses in the central nervous system also occurs in the absence of Nsf function. Expression of an nsf transgene in a null background indicates that stabilization of synapses requires Nsf function in both hair cells and afferent neurons. To identify potential targets of Nsf-mediated fusion, we examined the expression of genes implicated in stabilizing synapses and found that transcripts for multiple genes including brain-derived neurotrophic factor (bdnf) were significantly reduced in nsf mutants. With regard to trafficking of BDNF, we observed a striking accumulation of BDNF in the neurites of nsf mutant afferent neurons. In addition, injection of recombinant BDNF protein partially rescued the degeneration of afferent synapses in nsf mutants. These results establish a role for Nsf in the maintenance of synaptic contacts between hair cells and afferent neurons, mediated in part via the secretion of trophic signaling factors.
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Affiliation(s)
- Weike Mo
- Howard Hughes Medical Institute, Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Teresa Nicolson
- Howard Hughes Medical Institute, Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, Oregon, United States of America
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28
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Unraveling framework of the ancestral Mediator complex in human diseases. Biochimie 2011; 94:579-87. [PMID: 21983542 DOI: 10.1016/j.biochi.2011.09.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/15/2011] [Indexed: 01/13/2023]
Abstract
Mediator (MED) is a fundamental component of the RNA polymerase II-mediated transcription machinery. This multiprotein complex plays a pivotal role in the regulation of eukaryotic mRNA synthesis. The yeast Mediator complex consists of 26 different subunits. Recent studies indicate additional pathogenic roles for Mediator, for example during transcription elongation and non-coding RNA production. Mediator subunits have been emerging also to have pathophysiological roles suggesting MED-dependent therapeutic targets involving in several diseases, such as cancer, cardiovascular disease (CVD), metabolic and neurological disorders.
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29
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Muto A, Calof AL, Lander AD, Schilling TF. Multifactorial origins of heart and gut defects in nipbl-deficient zebrafish, a model of Cornelia de Lange Syndrome. PLoS Biol 2011; 9:e1001181. [PMID: 22039349 PMCID: PMC3201921 DOI: 10.1371/journal.pbio.1001181] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 09/13/2011] [Indexed: 12/31/2022] Open
Abstract
Cornelia de Lange Syndrome (CdLS) is the founding member of a class of multi-organ system birth defect syndromes termed cohesinopathies, named for the chromatin-associated protein complex cohesin, which mediates sister chromatid cohesion. Most cases of CdLS are caused by haploinsufficiency for Nipped-B-like (Nipbl), a highly conserved protein that facilitates cohesin loading. Consistent with recent evidence implicating cohesin and Nipbl in transcriptional regulation, both CdLS cell lines and tissues of Nipbl-deficient mice show changes in the expression of hundreds of genes. Nearly all such changes are modest, however--usually less than 1.5-fold--raising the intriguing possibility that, in CdLS, severe developmental defects result from the collective action of many otherwise innocuous perturbations. As a step toward testing this hypothesis, we developed a model of nipbl-deficiency in zebrafish, an organism in which we can quantitatively investigate the combinatorial effects of gene expression changes. After characterizing the structure and embryonic expression of the two zebrafish nipbl genes, we showed that morpholino knockdown of these genes produces a spectrum of specific heart and gut/visceral organ defects with similarities to those in CdLS. Analysis of nipbl morphants further revealed that, as early as gastrulation, expression of genes involved in endodermal differentiation (sox32, sox17, foxa2, and gata5) and left-right patterning (spaw, lefty2, and dnah9) is altered. Experimental manipulation of the levels of several such genes--using RNA injection or morpholino knockdown--implicated both additive and synergistic interactions in causing observed developmental defects. These findings support the view that birth defects in CdLS arise from collective effects of quantitative changes in gene expression. Interestingly, both the phenotypes and gene expression changes in nipbl morphants differed from those in mutants or morphants for genes encoding cohesin subunits, suggesting that the transcriptional functions of Nipbl cannot be ascribed simply to its role in cohesin loading.
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Affiliation(s)
- Akihiko Muto
- Department of Developmental and Cell Biology, University of California, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, California, United States of America
| | - Anne L. Calof
- Center for Complex Biological Systems, University of California, Irvine, California, United States of America
- Department of Anatomy and Neurobiology, University of California, Irvine, California, United States of America
| | - Arthur D. Lander
- Department of Developmental and Cell Biology, University of California, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, California, United States of America
| | - Thomas F. Schilling
- Department of Developmental and Cell Biology, University of California, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, California, United States of America
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30
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G protein-coupled receptor signaling and sphingosine-1-phosphate play a phylogenetically conserved role in endocrine pancreas morphogenesis. Mol Cell Biol 2011; 31:4442-53. [PMID: 21911471 DOI: 10.1128/mcb.05702-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During development pancreatic endocrine cells migrate in a coordinated fashion. This migration is necessary to form fully functional islets, but the mechanisms involved remain unknown. Therapeutic strategies to restore β-cell mass and islet functionality by reprogramming endogenous exocrine cells would be strengthened from simultaneous treatments that enhance endocrine cell clustering. We found that endocrine progenitors respond to and regulate G protein-coupled receptor (GPCR) signaling in order to cluster in islets. Rgs4, a dedicated regulator of GPCR signaling, was specifically expressed in early epithelial endocrine progenitors of both zebrafish and mouse, and its expression in the mouse endocrine progenitors was strictly dependent upon Ngn3, the key specification gene of the endocrine lineage. Rgs4 loss of function resulted in defects in islet cell aggregation. By genetically inactivating Gα(i)-mediated GPCR signaling in endocrine progenitors, we established its role in islet cell aggregation in both mouse and zebrafish. Finally, we identified sphingosine-1-phosphate (S1P) as a ligand mediating islet cell aggregation in both species acting through distinct but closely related receptors.
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Keightley MC, Layton JE, Hayman JW, Heath JK, Lieschke GJ. Mediator subunit 12 is required for neutrophil development in zebrafish. PLoS One 2011; 6:e23845. [PMID: 21901140 PMCID: PMC3162013 DOI: 10.1371/journal.pone.0023845] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 07/25/2011] [Indexed: 11/19/2022] Open
Abstract
Hematopoiesis requires the spatiotemporal organization of regulatory factors to successfully orchestrate diverse lineage specificity from stem and progenitor cells. Med12 is a regulatory component of the large Mediator complex that enables contact between the general RNA polymerase II transcriptional machinery and enhancer bound regulatory factors. We have identified a new zebrafish med12 allele, syr, with a single missense mutation causing a valine to aspartic acid change at position 1046. Syr shows defects in hematopoiesis, which predominantly affect the myeloid lineage. Syr has identified a hematopoietic cell-specific requirement for Med12, suggesting a new role for this transcriptional regulator.
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Affiliation(s)
- Maria-Cristina Keightley
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
- Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Judith E. Layton
- Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - John W. Hayman
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
- Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Joan K. Heath
- Colon Molecular and Cell Biology Laboratory, Melbourne Branch, Ludwig Institute for Cancer Research, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Graham J. Lieschke
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
- Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
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Hentges KE. Mediator complex proteins are required for diverse developmental processes. Semin Cell Dev Biol 2011; 22:769-75. [PMID: 21854862 DOI: 10.1016/j.semcdb.2011.07.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 12/14/2022]
Abstract
The Mediator complex serves a crucial function in gene regulation, forming a link between gene-specific transcription factors and RNA polymerase II. Most protein-coding genes therefore require Mediator complex activity for transcriptional regulation. Given the essential functions performed by Mediator complex proteins in gene regulation, it is not surprising that mutations in Mediator complex genes disrupt animal and plant development. What is more intriguing is that the phenotypes of individual Mediator complex mutants are distinct from each other, demonstrating that certain developmental processes have a greater requirement for specific Mediator complex genes. Additionally, the range of developmental processes that are altered in Mediator complex mutants is broad, affecting a variety of cell types and physiological systems. Gene expression defects in Mediator complex mutants reveal distinct roles for individual Mediator proteins in transcriptional regulation, suggesting that the deletion of one Mediator complex protein does not interfere with transcription in general, but instead alters the expression of specific target genes. Mediator complex proteins may have diverse roles in different organisms as well, as mutants in the same Mediator gene in different species can display dissimilar phenotypes.
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Affiliation(s)
- Kathryn E Hentges
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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Mediator and human disease. Semin Cell Dev Biol 2011; 22:776-87. [PMID: 21840410 DOI: 10.1016/j.semcdb.2011.07.024] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 01/21/2023]
Abstract
Since the identification of a metazoan counterpart to yeast Mediator nearly 15 years ago, a convergent body of biochemical and molecular genetic studies have confirmed their structural and functional relationship as an integrative hub through which regulatory information conveyed by signal activated transcription factors is transduced to RNA polymerase II. Nonetheless, metazoan Mediator complexes have been shaped during evolution by substantive diversification and expansion in both the number and sequence of their constituent subunits, with important implications for the development of multicellular organisms. The appearance of unique interaction surfaces within metazoan Mediator complexes for transcription factors of diverse species-specific origins extended the role of Mediator to include an essential function in coupling developmentally coded signals with precise gene expression output sufficient to specify cell fate and function. The biological significance of Mediator in human development, suggested by genetic studies in lower metazoans, is emphatically illustrated by an expanding list of human pathologies linked to genetic variation or aberrant expression of its individual subunits. Here, we review our current body of knowledge concerning associations between individual Mediator subunits and specific pathological disorders. When established, molecular etiologies underlying genotype-phenotype correlations are addressed, and we anticipate that future progress in this critical area will help identify therapeutic targets across a range of human pathologies.
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The transcriptional mediator component Med12 is required for hindbrain boundary formation. PLoS One 2011; 6:e19076. [PMID: 21533047 PMCID: PMC3080914 DOI: 10.1371/journal.pone.0019076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 03/23/2011] [Indexed: 11/30/2022] Open
Abstract
Background Rhombomere boundaries form during hindbrain segmentation and are critical for maintaining segmental integrity and regulating migration in the hindbrain. Some genetic models affecting hindbrain boundary formation have been described, but involvement of components of the transcriptional mediator complex in boundary formation has not reported so far. Principal Findings The kto/med12 mutant zebrafish, which affects the Mediator component Med12, causes specific loss of rhombomere boundary cells even though segmentation of the hindbrain takes place at least in part. In kto mutant embryos, cells forming rhombomere boundaries were largely absent as indicated by the use of several marker genes. While no obvious increase in cell death was observed, we found a notable reduction of cell proliferation in the hindbrain of kto mutant zebrafish. Conclusions The kto/med12 mutation results in specific defects of boundary cell formation in the zebrafish hindbrain.
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Hesselson D, Anderson RM, Stainier DYR. Suppression of Ptf1a activity induces acinar-to-endocrine conversion. Curr Biol 2011; 21:712-7. [PMID: 21497092 DOI: 10.1016/j.cub.2011.03.041] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 03/01/2011] [Accepted: 03/15/2011] [Indexed: 11/25/2022]
Abstract
Pluripotent embryonic cells become progressively lineage restricted during development in a process that culminates in the differentiation of stable organ-specific cell types that perform specialized functions. Terminally differentiated pancreatic acinar cells do not have the innate capacity to contribute to the endocrine β cell lineage, which is destroyed in individuals with autoimmune diabetes. Some cell types can be reprogrammed using a single factor, whereas other cell types require continuous activity of transcriptional regulators to repress alternate cell fates. Thus, we hypothesized that a transcriptional network continuously maintains the pancreatic acinar cell fate. We found that postembryonic antagonism of Ptf1a, a master regulator of pancreatic development and acinar cell fate specification, induced the expression of endocrine genes including insulin in the exocrine compartment. Using a genetic lineage tracing approach, we show that the induced insulin+ cells are derived from acinar cells. Cellular reprogramming occurred under homeostatic conditions, suggesting that the pancreatic microenvironment is sufficient to promote endocrine differentiation. Thus, severe experimental manipulations may not be required to potentiate pancreatic transdifferentiation. These data indicate that targeted postembryonic disruption of the acinar cell fate can restore the developmental plasticity that is lost during development.
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Affiliation(s)
- Daniel Hesselson
- Department of Biochemistry and Biophysics, Programs in Developmental and Stem Cell Biology, Genetics, and Human Genetics, Institute for Regeneration Medicine, Liver Center, and Diabetes Center, University of California, San Francisco, 1550 Fourth Street, San Francisco, CA 94158, USA.
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Klein C, Mikutta J, Krueger J, Scholz K, Brinkmann J, Liu D, Veerkamp J, Siegel D, Abdelilah-Seyfried S, le Noble F. Neuron navigator 3a regulates liver organogenesis during zebrafish embryogenesis. Development 2011; 138:1935-45. [PMID: 21471154 DOI: 10.1242/dev.056861] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endodermal organogenesis requires a precise orchestration of cell fate specification and cell movements, collectively coordinating organ size and shape. In Caenorhabditis elegans, uncoordinated-53 (unc-53) encodes a neural guidance molecule that directs axonal growth. One of the vertebrate homologs of unc-53 is neuron navigator 3 (Nav3). Here, we identified a novel vertebrate neuron navigator 3 isoform in zebrafish, nav3a, and we provide genetic evidence in loss- and gain-of-function experiments showing its functional role in endodermal organogenesis during zebrafish embryogenesis. In zebrafish embryos, nav3a expression was initiated at 22 hpf in the gut endoderm and at 40 hpf expanded to the newly formed liver bud. Endodermal nav3a expression was controlled by Wnt2bb signaling and was independent of FGF and BMP signaling. Morpholino-mediated knockdown of nav3a resulted in a significantly reduced liver size, and impaired development of pancreas and swim bladder. In vivo time-lapse imaging of liver development in nav3a morphants revealed a failure of hepatoblast movement out from the gut endoderm during the liver budding stage, with hepatoblasts being retained in the intestinal endoderm. In hepatocytes in vitro, nav3a acts as a positive modulator of actin assembly in lamellipodia and filipodia extensions, allowing cellular movement. Knockdown of nav3a in vitro impeded hepatocyte movement. Endodermal-specific overexpression of nav3a in vivo resulted in additional ectopic endodermal budding beyond the normal liver and pancreatic budding sites. We conclude that nav3a is required for directing endodermal organogenesis involving coordination of endodermal cell behavior.
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Affiliation(s)
- Christian Klein
- Department of Angiogenesis and Cardiovascular Pathology, Max-Delbrueck-Center for Molecular Medicine (MDC), Berlin, Germany
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Rump P, Niessen RC, Verbruggen KT, Brouwer OF, de Raad M, Hordijk R. A novel mutation in MED12 causes FG syndrome (Opitz-Kaveggia syndrome). Clin Genet 2011; 79:183-8. [PMID: 20507344 DOI: 10.1111/j.1399-0004.2010.01449.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Opitz-Kaveggia syndrome is a rare X-linked multiple congenital anomalies and intellectual disability disorder caused by the recurrent p.R961W mutation in the MED12 gene. Twenty-three affected males from 10 families with this mutation in the MED12 gene have been described so far. Here we report on a new family with three affected cousins, in which we identified a novel MED12 mutation (p.G958E). This is the first demonstration that other mutations in this gene can also lead to Opitz-Kaveggia syndrome. The clinical phenotype of these three new cases is reviewed in detail and compared with the previous reported cases.
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Affiliation(s)
- P Rump
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Rocha PP, Scholze M, Bleiss W, Schrewe H. Med12 is essential for early mouse development and for canonical Wnt and Wnt/PCP signaling. Development 2010; 137:2723-31. [PMID: 20630950 DOI: 10.1242/dev.053660] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Mediator complex is commonly seen as a molecular bridge that connects DNA-bound transcription factors to the RNA polymerase II (Pol II) machinery. It is a large complex of 30 subunits that is present in all eukaryotes. The Med12 subunit has been implicated not only in the regulation of Pol II activity, but also in the binding of transcription factors to the bulk of the Mediator complex. We targeted Med12 in mouse embryonic stem cells to investigate the in vivo function of this subunit. We report here the developmental defects of Med12 hypomorphic mutants that have a drastic reduction in Med12 protein levels. These mutants fail to develop beyond embryonic day 10 and have severe defects in neural tube closure, axis elongation, somitogenesis and heart formation. We show that in Med12 hypomorphic embryos, the Wnt/planar cell polarity pathway is disrupted and that canonical Wnt/beta-catenin signaling is impaired. In agreement with this, embryos that are incapable of Med12 expression failed to establish the anterior visceral endoderm or activate brachyury expression, and did not complete gastrulation.
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Affiliation(s)
- Pedro P Rocha
- Institute of Medical Genetics, Charité-University Medicine Berlin, Berlin 12200, Germany
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Rienzo M, Nagel J, Casamassimi A, Giovane A, Dietzel S, Napoli C. Mediator subunits: gene expression pattern, a novel transcript identification and nuclear localization in human endothelial progenitor cells. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1799:487-495. [PMID: 20493979 DOI: 10.1016/j.bbagrm.2010.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 05/03/2010] [Accepted: 05/05/2010] [Indexed: 05/29/2023]
Abstract
Mediator of RNA polymerase II transcription subunits (MEDs) serve to promote the assembly, activation, and regeneration of transcription complexes on core promoters during the initiation and re-initiation phases of transcription. There are no studies on the Mediator complex during development of endothelial progenitors (EPCs). Here, we have analysed all known MEDs during the differentiation of EPCs, by expression profile studies at RNA level and, for a limited subset of MED subunits, also at protein level. Since beneficial effects of L-arginine on EPCs have been described, we have also examined its effect on the expression of Mediator subunit coding genes. Through RT-PCR we have found increased expression for MED12 and decreased levels for MED30 after l-arginine treatment; Western blot analysis do not agree entirely with the RNA data in the identification of a putative protein product. Furthermore, we have analysed the three-dimensional nuclear positions of MED12 and MED30 genes in the presence of l-arginine treatment. Our major finding is the identification of a novel transcript of MED30, termed MED30 short (MED30s) generating by alternative splicing. Our results showed that the mRNA of this novel isoform is present only in circulating cells, but it is not expressed in cultured adherent cells. These findings are broadly relevant and will contribute to our understanding of the role of Mediator in eukaryotic gene expression. Despite the need to confirm the in vivo presence of the protein of this novel isoform, the presence of this novel RNA raises the possibility of regulating pathophysiological mechanism in progenitors.
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Affiliation(s)
- Monica Rienzo
- Department of General Pathology, 1st School of Medicine, II University of Naples, 80138 Naples, Italy
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40
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Tiso N, Moro E, Argenton F. Zebrafish pancreas development. Mol Cell Endocrinol 2009; 312:24-30. [PMID: 19477220 DOI: 10.1016/j.mce.2009.04.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 04/28/2009] [Accepted: 04/30/2009] [Indexed: 10/20/2022]
Abstract
An accurate understanding of the molecular events governing pancreas development can have an impact on clinical medicine related to diabetes, obesity and pancreatic cancer, diseases with a high impact in public health. Until 1996, the main animal models in which pancreas formation and differentiation could be studied were mouse and, for some instances related to early development, chicken and Xenopus. Zebrafish has penetrated this field very rapidly offering a new model of investigation; by joining functional genomics, genetics and in vivo whole mount visualization, Danio rerio has allowed large scale and fine multidimensional analysis of gene functions during pancreas formation and differentiation.
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Affiliation(s)
- Natascia Tiso
- Dipartimento di Biologia, Universita' degli Studi di Padova, Via Ugo Bassi 58b, I-35121 Padova, Italy
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41
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Distinct populations of quiescent and proliferative pancreatic beta-cells identified by HOTcre mediated labeling. Proc Natl Acad Sci U S A 2009; 106:14896-901. [PMID: 19706417 DOI: 10.1073/pnas.0906348106] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pancreatic beta-cells are critical regulators of glucose homeostasis, and they vary dramatically in their glucose stimulated metabolic response and levels of insulin secretion. It is unclear whether these parameters are influenced by the developmental origin of individual beta-cells. Using HOTcre, a Cre-based genetic switch that uses heat-induction to precisely control the temporal expression of transgenes, we labeled two populations of beta-cells within the developing zebrafish pancreas. These populations originate in distinct pancreatic buds and exhibit gene expression profiles suggesting distinct functions during development. We find that the dorsal bud derived beta-cells are quiescent and exhibit a marked decrease in insulin expression postembryonically. In contrast, ventral bud derived beta-cells proliferate actively, and maintain high levels of insulin expression compared with dorsal bud derived beta-cells. Therapeutic strategies to regulate beta-cell proliferation and function are required to cure pathological states that result from excessive beta-cell proliferation (e.g., insulinoma) or insufficient beta-cell mass (e.g., diabetes mellitus). Our data reveal the existence of distinct populations of beta-cells in vivo and should help develop better strategies to regulate beta-cell differentiation and proliferation.
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Anderson RM, Bosch JA, Goll MG, Hesselson D, Dong PDS, Shin D, Chi NC, Shin CH, Schlegel A, Halpern M, Stainier DYR. Loss of Dnmt1 catalytic activity reveals multiple roles for DNA methylation during pancreas development and regeneration. Dev Biol 2009; 334:213-23. [PMID: 19631206 DOI: 10.1016/j.ydbio.2009.07.017] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 07/07/2009] [Accepted: 07/15/2009] [Indexed: 02/02/2023]
Abstract
Developmental mechanisms regulating gene expression and the stable acquisition of cell fate direct cytodifferentiation during organogenesis. Moreover, it is likely that such mechanisms could be exploited to repair or regenerate damaged organs. DNA methyltransferases (Dnmts) are enzymes critical for epigenetic regulation, and are used in concert with histone methylation and acetylation to regulate gene expression and maintain genomic integrity and chromosome structure. We carried out two forward genetic screens for regulators of endodermal organ development. In the first, we screened for altered morphology of developing digestive organs, while in the second we screed for the lack of terminally differentiated cell types in the pancreas and liver. From these screens, we identified two mutant alleles of zebrafish dnmt1. Both lesions are predicted to eliminate dnmt1 function; one is a missense mutation in the catalytic domain and the other is a nonsense mutation that eliminates the catalytic domain. In zebrafish dnmt1 mutants, the pancreas and liver form normally, but begin to degenerate after 84 h post fertilization (hpf). Acinar cells are nearly abolished through apoptosis by 100 hpf, though neither DNA replication, nor entry into mitosis is halted in the absence of detectable Dnmt1. However, endocrine cells and ducts are largely spared. Surprisingly, dnmt1 mutants and dnmt1 morpholino-injected larvae show increased capacity for pancreatic beta cell regeneration in an inducible model of pancreatic beta cell ablation. Thus, our data suggest that Dnmt1 is dispensable for pancreatic duct or endocrine cell formation, but not for acinar cell survival. In addition, Dnmt1 may influence the differentiation of pancreatic beta cell progenitors or the reprogramming of cells toward the pancreatic beta cell fate.
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Affiliation(s)
- Ryan M Anderson
- Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics, and Human Genetics, Diabetes Center, and Liver Center, University of California, San Francisco, San Francisco, CA 94158-2324, USA. (
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