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Fiegl M, Kimmel RA. Laboratory Course Using Zebrafish to Uncover Changing Roles of Wnt Signaling in Early Vertebrate Development. Zebrafish 2024; 21:128-136. [PMID: 38621212 DOI: 10.1089/zeb.2023.0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024] Open
Abstract
Coordinated signaling pathway activity directs early patterning to set up the vertebrate body plan. Perturbations in the timing or location of signal molecule expression impacts embryo morphology and organ formation. In this study, we present a laboratory course to use zebrafish for studying the role of Wnt signaling in specifying the early embryonic axes. Students are exposed to basic techniques in molecular and developmental biology, including embryo manipulation, fluorescence microscopy, image processing, and data analysis. Furthermore, this course incorporates student-designed experiments to stimulate independent inquiry and improve scientific learning, providing an experience resembling graduate-level laboratory research. Students appreciated following vertebrate development in real-time, and principles of embryogenesis were reinforced by observing the morphological changes that arise due to signaling alterations. Scientific and research skills were enhanced through practice in experimental design, interpretation, and presentation.
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Affiliation(s)
- Manuel Fiegl
- Institute of Molecular Biology/CMBI, University of Innsbruck, Innsbruck, Austria
- Cardiac Surgery Research Lab, Department of Cardiac Surgery, Medical University of Innsbruck, Innsbruck, Austria
| | - Robin A Kimmel
- Institute of Molecular Biology/CMBI, University of Innsbruck, Innsbruck, Austria
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Freudenblum J, Meyer D, Kimmel RA. Mitochondrial network expansion and dynamic redistribution during islet morphogenesis in zebrafish larvae. FEBS Lett 2023; 597:262-275. [PMID: 36217213 PMCID: PMC10092693 DOI: 10.1002/1873-3468.14508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/14/2022] [Accepted: 09/20/2022] [Indexed: 01/26/2023]
Abstract
Mitochondria, organelles critical for energy production, modify their shape and location in response to developmental state and metabolic demands. Mitochondria are altered in diabetes, but the mechanistic basis is poorly defined, due to difficulties in assessing mitochondria within an intact organism. Here, we use in vivo imaging in transparent zebrafish larvae to demonstrate filamentous, interconnected mitochondrial networks within islet cells. Mitochondrial movements highly resemble what has been reported for human islet cells in vitro, showing conservation in behaviour across species and cellular context. During islet development, mitochondrial content increases with emergence of cell motility, and mitochondria disperse within fine protrusions. Overall, this work presents quantitative analysis of mitochondria within their native environment and provides insights into mitochondrial behaviour during organogenesis.
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Affiliation(s)
| | - Dirk Meyer
- Institute of Molecular Biology/CMBIUniversity of InnsbruckAustria
| | - Robin A. Kimmel
- Institute of Molecular Biology/CMBIUniversity of InnsbruckAustria
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Schmitner N, Recheis C, Thönig J, Kimmel RA. Differential Responses of Neural Retina Progenitor Populations to Chronic Hyperglycemia. Cells 2021; 10:cells10113265. [PMID: 34831487 PMCID: PMC8622914 DOI: 10.3390/cells10113265] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/08/2021] [Accepted: 11/18/2021] [Indexed: 12/30/2022] Open
Abstract
Diabetic retinopathy is a frequent complication of longstanding diabetes, which comprises a complex interplay of microvascular abnormalities and neurodegeneration. Zebrafish harboring a homozygous mutation in the pancreatic transcription factor pdx1 display a diabetic phenotype with survival into adulthood, and are therefore uniquely suitable among zebrafish models for studying pathologies associated with persistent diabetic conditions. We have previously shown that, starting at three months of age, pdx1 mutants exhibit not only vascular but also neuro-retinal pathologies manifesting as photoreceptor dysfunction and loss, similar to human diabetic retinopathy. Here, we further characterize injury and regenerative responses and examine the effects on progenitor cell populations. Consistent with a negative impact of hyperglycemia on neurogenesis, stem cells of the ciliary marginal zone show an exacerbation of aging-related proliferative decline. In contrast to the robust Müller glial cell proliferation seen following acute retinal injury, the pdx1 mutant shows replenishment of both rod and cone photoreceptors from slow-cycling, neurod-expressing progenitors which first accumulate in the inner nuclear layer. Overall, we demonstrate a diabetic retinopathy model which shows pathological features of the human disease evolving alongside an ongoing restorative process that replaces lost photoreceptors, at the same time suggesting an unappreciated phenotypic continuum between multipotent and photoreceptor-committed progenitors.
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Freudenblum J, Meyer D, Kimmel RA. Inducible Mosaic Cell Labeling Provides Insights Into Pancreatic Islet Morphogenesis. Front Cell Dev Biol 2020; 8:586651. [PMID: 33102488 PMCID: PMC7546031 DOI: 10.3389/fcell.2020.586651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/02/2020] [Indexed: 11/13/2022] Open
Abstract
Pancreatic islets, discrete microorgans embedded within the exocrine pancreas, contain beta cells which are critical for glucose homeostasis. Loss or dysfunction of beta cells leads to diabetes, a disease with expanding global prevalence, and for which regenerative therapies are actively being pursued. Recent efforts have focused on producing mature beta cells in vitro, but it is increasingly recognized that achieving a faithful three-dimensional islet structure is crucial for generating fully functional beta cells. Our current understanding of islet morphogenesis is far from complete, due to the deep internal location of the pancreas in mammalian models, which hampers direct visualization. Zebrafish is a model system well suited for studies of pancreas morphogenesis due to its transparency and the accessible location of the larval pancreas. In order to further clarify the cellular mechanisms of islet formation, we have developed new tools for in vivo visualization of single-cell dynamics. Our results show that clustering islet cells make contact and interconnect through dynamic actin-rich processes, move together while remaining in close proximity to the duct, and maintain high protrusive motility after forming clusters. Quantitative analyses of cell morphology and motility in 3-dimensions lays the groundwork to define therapeutically applicable factors responsible for orchestrating the morphogenic behaviors of coalescing endocrine cells.
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Affiliation(s)
- Julia Freudenblum
- Institute of Molecular Biology/CMBI, University of Innsbruck, Innsbruck, Austria
| | - Dirk Meyer
- Institute of Molecular Biology/CMBI, University of Innsbruck, Innsbruck, Austria
| | - Robin A Kimmel
- Institute of Molecular Biology/CMBI, University of Innsbruck, Innsbruck, Austria
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Ali Z, Zang J, Lagali N, Schmitner N, Salvenmoser W, Mukwaya A, Neuhauss SCF, Jensen LD, Kimmel RA. Photoreceptor Degeneration Accompanies Vascular Changes in a Zebrafish Model of Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2020; 61:43. [PMID: 32106290 PMCID: PMC7329949 DOI: 10.1167/iovs.61.2.43] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose Diabetic retinopathy (DR) is a leading cause of vision impairment and blindness worldwide in the working-age population, and the incidence is rising. Until now it has been difficult to define initiating events and disease progression at the molecular level, as available diabetic rodent models do not present the full spectrum of neural and vascular pathologies. Zebrafish harboring a homozygous mutation in the pancreatic transcription factor pdx1 were previously shown to display a diabetic phenotype from larval stages through adulthood. In this study, pdx1 mutants were examined for retinal vascular and neuronal pathology to demonstrate suitability of these fish for modeling DR. Methods Vessel morphology was examined in pdx1 mutant and control fish expressing the fli1a:EGFP transgene. We further characterized vascular and retinal phenotypes in mutants and controls using immunohistochemistry, histology, and electron microscopy. Retinal function was assessed using electroretinography. Results Pdx1 mutants exhibit clear vascular phenotypes at 2 months of age, and disease progression, including arterial vasculopenia, capillary tortuosity, and hypersprouting, could be detected at stages extending over more than 1 year. Neural-retinal pathologies are consistent with photoreceptor dysfunction and loss, but do not progress to blindness. Conclusions This study highlights pdx1 mutant zebrafish as a valuable complement to rodent and other mammalian models of DR, in particular for research into the mechanistic interplay of diabetes with vascular and neuroretinal disease. They are furthermore suited for molecular studies to identify new targets for treatment of early as well as late DR.
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Fischer P, Chen H, Pacho F, Rieder D, Kimmel RA, Meyer D. FoxH1 represses miR-430 during early embryonic development of zebrafish via non-canonical regulation. BMC Biol 2019; 17:61. [PMID: 31362746 PMCID: PMC6664792 DOI: 10.1186/s12915-019-0683-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/19/2019] [Indexed: 12/19/2022] Open
Abstract
Background FoxH1 is a forkhead transcription factor with conserved key functions in vertebrate mesoderm induction and left-right patterning downstream of the TGF-beta/Nodal signaling pathway. Binding of the forkhead domain (FHD) of FoxH1 to a highly conserved proximal sequence motif was shown to regulate target gene expression. Results We identify the conserved microRNA-430 family (miR-430) as a novel target of FoxH1. miR-430 levels are increased in foxH1 mutants, resulting in a reduced expression of transcripts that are targeted by miR-430 for degradation. To determine the underlying mechanism of miR-430 repression, we performed chromatin immunoprecipitation studies and overexpression experiments with mutant as well as constitutive active and repressive forms of FoxH1. Our studies reveal a molecular interaction of FoxH1 with miR-430 loci independent of the FHD. Furthermore, we show that previously described mutant forms of FoxH1 that disrupt DNA binding or that lack the C-terminal Smad Interaction Domain (SID) dominantly interfere with miR-430 repression, but not with the regulation of previously described FoxH1 targets. Conclusions We were able to identify the distinct roles of protein domains of FoxH1 in the regulation process of miR-430. We provide evidence that the indirect repression of miR-430 loci depends on the connection to a distal repressive chromosome environment via a non-canonical mode. The widespread distribution of such non-canonical binding sites of FoxH1, found not only in our study, argues against a function restricted to regulating miR-430 and for a more global role of FoxH1 in chromatin folding. Electronic supplementary material The online version of this article (10.1186/s12915-019-0683-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patrick Fischer
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Hao Chen
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Frederic Pacho
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Dietmar Rieder
- Division of Bioinformatics, Biocenter, Innsbruck Medical University, Innrain 80, 6020, Innsbruck, Austria
| | - Robin A Kimmel
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Dirk Meyer
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria.
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Freudenblum J, Iglesias JA, Hermann M, Walsen T, Wilfinger A, Meyer D, Kimmel RA. In vivo imaging of emerging endocrine cells reveals a requirement for PI3K-regulated motility in pancreatic islet morphogenesis. Development 2018; 145:dev.158477. [PMID: 29386244 PMCID: PMC5818004 DOI: 10.1242/dev.158477] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/10/2018] [Indexed: 01/03/2023]
Abstract
The three-dimensional architecture of the pancreatic islet is integral to beta cell function, but the process of islet formation remains poorly understood due to the difficulties of imaging internal organs with cellular resolution. Within transparent zebrafish larvae, the developing pancreas is relatively superficial and thus amenable to live imaging approaches. We performed in vivo time-lapse and longitudinal imaging studies to follow islet development, visualizing both naturally occurring islet cells and cells arising with an accelerated timecourse following an induction approach. These studies revealed previously unappreciated fine dynamic protrusions projecting between neighboring and distant endocrine cells. Using pharmacological compound and toxin interference approaches, and single-cell analysis of morphology and cell dynamics, we determined that endocrine cell motility is regulated by phosphoinositide 3-kinase (PI3K) and G-protein-coupled receptor (GPCR) signaling. Linking cell dynamics to islet formation, perturbation of protrusion formation disrupted endocrine cell coalescence, and correlated with decreased islet cell differentiation. These studies identified novel cell behaviors contributing to islet morphogenesis, and suggest a model in which dynamic exploratory filopodia establish cell-cell contacts that subsequently promote cell clustering. Summary: Pancreatic endocrine cells extend previously unrecognized dynamic, flexible, fine projections to guide clustering into a compacted islet in a process regulated by PI3K and GPCR.
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Affiliation(s)
- Julia Freudenblum
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - José A Iglesias
- Johann Radon Institute for Computational and Applied Mathematics (RICAM), Austrian Academy of Sciences, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Martin Hermann
- Department of Anaesthesiology and Critical Care Medicine, Innsbruck Medical University, Innrain 66, 6020 Innsbruck, Austria
| | - Tanja Walsen
- Department of Neurosurgery, Medical University of Innsbruck, 6020 Innsbruck Austria
| | - Armin Wilfinger
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Dirk Meyer
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Robin A Kimmel
- Institute of Molecular Biology/CMBI, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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Li J, Casteels T, Frogne T, Ingvorsen C, Honoré C, Courtney M, Huber KVM, Schmitner N, Kimmel RA, Romanov RA, Sturtzel C, Lardeau CH, Klughammer J, Farlik M, Sdelci S, Vieira A, Avolio F, Briand F, Baburin I, Májek P, Pauler FM, Penz T, Stukalov A, Gridling M, Parapatics K, Barbieux C, Berishvili E, Spittler A, Colinge J, Bennett KL, Hering S, Sulpice T, Bock C, Distel M, Harkany T, Meyer D, Superti-Furga G, Collombat P, Hecksher-Sørensen J, Kubicek S. Artemisinins Target GABA A Receptor Signaling and Impair α Cell Identity. Cell 2016; 168:86-100.e15. [PMID: 27916275 PMCID: PMC5236063 DOI: 10.1016/j.cell.2016.11.010] [Citation(s) in RCA: 263] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 08/04/2016] [Accepted: 11/03/2016] [Indexed: 12/12/2022]
Abstract
Type 1 diabetes is characterized by the destruction of pancreatic β cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types, including glucagon-producing α cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of α cells to functional β-like cells. Here, we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalarial drugs and that the mechanism of action of these molecules depends on the enhancement of GABAA receptor signaling. Our results in zebrafish, rodents, and primary human pancreatic islets identify gephyrin as a druggable target for the regeneration of pancreatic β cell mass from α cells. Artemisinins inhibit ARX function and impair α cell identity Compounds act by stabilizing gephyrin, thus enhancing GABAA receptor signaling Artemisinins increase β cell mass in zebrafish and rodent models Functional and transcriptional data indicate a conserved phenotype in human islets
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Affiliation(s)
- Jin Li
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Tamara Casteels
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Thomas Frogne
- Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | | | | | - Monica Courtney
- Université Côte d'Azur, INSERM, CNRS, iBV, 06108 Nice, France
| | - Kilian V M Huber
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Nicole Schmitner
- Institute of Molecular Biology, Leopold-Franzens-University Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Robin A Kimmel
- Institute of Molecular Biology, Leopold-Franzens-University Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Roman A Romanov
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria; Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Caterina Sturtzel
- Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090 Vienna, Austria
| | - Charles-Hugues Lardeau
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria; Christian Doppler Laboratory for Chemical Epigenetics and Antiinfectives, CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090 Vienna, Austria
| | - Johanna Klughammer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Matthias Farlik
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Sara Sdelci
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Andhira Vieira
- Université Côte d'Azur, INSERM, CNRS, iBV, 06108 Nice, France
| | - Fabio Avolio
- Université Côte d'Azur, INSERM, CNRS, iBV, 06108 Nice, France
| | - François Briand
- Physiogenex S.A.S., Prologue Biotech, 516, rue Pierre et Marie Curie, 31670 Labege, France
| | - Igor Baburin
- Institute of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Peter Májek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Florian M Pauler
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Thomas Penz
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Alexey Stukalov
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Manuela Gridling
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Katja Parapatics
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Charlotte Barbieux
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland
| | - Ekaterine Berishvili
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland; Institute of Medical Research, Ilia State University, Tbilisi 0162, Georgia
| | - Andreas Spittler
- Core Facility Flow Cytometry and Department of Surgery, Research Laboratories, Medical University of Vienna, 1090 Vienna, Austria
| | - Jacques Colinge
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Keiryn L Bennett
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria
| | - Steffen Hering
- Institute of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Thierry Sulpice
- Physiogenex S.A.S., Prologue Biotech, 516, rue Pierre et Marie Curie, 31670 Labege, France
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria; Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria; Max Planck Institute for Informatics, 66123 Saarbrücken, Germany
| | - Martin Distel
- Children's Cancer Research Institute, Innovative Cancer Models, Zimmermannplatz 10, 1090 Vienna, Austria
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria; Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Dirk Meyer
- Institute of Molecular Biology, Leopold-Franzens-University Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | | | | | - Stefan Kubicek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. Lazarettgasse 14, 1090 Vienna, Austria; Christian Doppler Laboratory for Chemical Epigenetics and Antiinfectives, CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090 Vienna, Austria.
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Kimmel RA, Dobler S, Schmitner N, Walsen T, Freudenblum J, Meyer D. Diabetic pdx1-mutant zebrafish show conserved responses to nutrient overload and anti-glycemic treatment. Sci Rep 2015; 5:14241. [PMID: 26384018 PMCID: PMC4585597 DOI: 10.1038/srep14241] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 08/20/2015] [Indexed: 01/09/2023] Open
Abstract
Diabetes mellitus is characterized by disrupted glucose homeostasis due to loss or dysfunction of insulin-producing beta cells. In this work, we characterize pancreatic islet development and function in zebrafish mutant for pdx1, a gene which in humans is linked to genetic forms of diabetes and is associated with increased susceptibility to Type 2 diabetes. Pdx1 mutant zebrafish have the key diabetic features of reduced beta cells, decreased insulin and elevated glucose. The hyperglycemia responds to pharmacologic anti-diabetic treatment and, as often seen in mammalian diabetes models, beta cells of pdx1 mutants show sensitivity to nutrient overload. This unique genetic model of diabetes provides a new tool for elucidating the mechanisms behind hyperglycemic pathologies and will allow the testing of novel therapeutic interventions in a model organism that is amenable to high-throughput approaches.
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Affiliation(s)
- Robin A Kimmel
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stefan Dobler
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Nicole Schmitner
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Tanja Walsen
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Julia Freudenblum
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Dirk Meyer
- Institute of Molecular Biology/CMBI; Leopold-Francis University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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Kimmel RA, Onder L, Wilfinger A, Ellertsdottir E, Meyer D. Requirement for Pdx1 in specification of latent endocrine progenitors in zebrafish. BMC Biol 2011; 9:75. [PMID: 22034951 PMCID: PMC3215967 DOI: 10.1186/1741-7007-9-75] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/31/2011] [Indexed: 12/17/2022] Open
Abstract
Background Insulin-producing beta cells emerge during pancreas development in two sequential waves. Recently described later-forming beta cells in zebrafish show high similarity to second wave mammalian beta cells in developmental capacity. Loss-of-function studies in mouse and zebrafish demonstrated that the homeobox transcription factors Pdx1 and Hb9 are both critical for pancreas and beta cell development and discrete stage-specific requirements for these genes have been uncovered. Previously, exocrine and endocrine cell recovery was shown to follow loss of pdx1 in zebrafish, but the progenitor cells and molecular mechanisms responsible have not been clearly defined. In addition, interactions of pdx1 and hb9 in beta cell formation have not been addressed. Results To learn more about endocrine progenitor specification, we examined beta cell formation following morpholino-mediated depletion of pdx1 and hb9. We find that after early beta cell reduction, recovery occurs following loss of either pdx1 or hb9 function. Unexpectedly, simultaneous knockdown of both hb9 and pdx1 leads to virtually complete and persistent beta cell deficiency. We used a NeuroD:EGFP transgenic line to examine endocrine cell behavior in vivo and developed a novel live-imaging technique to document emergence and migration of late-forming endocrine precursors in real time. Our data show that Notch-responsive progenitors for late-arising endocrine cells are predominantly post mitotic and depend on pdx1. By contrast, early-arising endocrine cells are specified and differentiate independent of pdx1. Conclusions The nearly complete beta cell deficiency after combined loss of hb9 and pdx1 suggests functional cooperation, which we clarify as distinct roles in early and late endocrine cell formation. A novel imaging approach permitted visualization of the emergence of late endocrine cells within developing embryos for the first time. We demonstrate a pdx1-dependent progenitor population essential for the formation of duct-associated, second wave endocrine cells. We further reveal an unexpectedly low mitotic activity in these progenitor cells, indicating that they are set aside early in development.
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Affiliation(s)
- Robin A Kimmel
- Institute of Molecular Biology/CMBI; Leopold-Francis University, Technikerstrasse 25, A-6020 Innsbruck, Austria.
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Abstract
The pancreas is a vertebrate-specific organ of endodermal origin which is responsible for production of digestive enzymes and hormones involved in regulating glucose homeostasis, in particular insulin, deficiency of which results in diabetes. Basic research on the genetic and molecular pathways regulating pancreas formation and function has gained major importance for the development of regenerative medical approaches aimed at improving diabetes treatment. Among the different model organisms that are currently used to elucidate the basic pathways of pancreas development and regeneration, the zebrafish is distinguished by its unique opportunities to combine genetic and pharmacological approaches with sophisticated live-imaging methodology, and by its ability to regenerate the pancreas within a short time. Here we review current perspectives and present methods for studying two important processes contributing to pancreas development and regeneration, namely cell migration via time-lapse micropscopy and cell proliferation via incorporation of nucleotide analog EdU, with a focus on the insulin-producing beta cells of the islet.
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Affiliation(s)
- Robin A Kimmel
- Institute of Molecular Biology, University of Innsbruck, A-6020 Innsbruck, Austria
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Kimmel RA, Turnbull DH, Blanquet V, Wurst W, Loomis CA, Joyner AL. ABSTRACT Two lineage boundaries and En1 coordinate AER formation. Biochem Cell Biol 2000. [DOI: 10.1139/o00-035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Kimmel RA, Turnbull DH, Blanquet V, Wurst W, Loomis CA, Joyner AL. Two lineage boundaries coordinate vertebrate apical ectodermal ridge formation. Genes Dev 2000; 14:1377-89. [PMID: 10837030 PMCID: PMC316660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Proximal-distal outgrowth of the vertebrate limb bud is regulated by the apical ectodermal ridge (AER), which forms at an invariant position along the dorsal-ventral (D/V) axis of the embryo. We have studied the genetic and cellular events that regulate AER formation in the mouse. In contrast to implications from previous studies in chick, we identified two distinct lineage boundaries in mouse ectoderm prior to limb bud outgrowth using a Cre/loxP-based fate-mapping approach and a novel retroviral cell-labeling technique. One border is transient and at the limit of expression of the ventral gene En1, which corresponds to the D/V midline of the AER, and the second border corresponds to the dorsal AER margin. Labeling of AER precursors using an inducible Cre showed that not all cells that initially express AER genes form the AER, indicating that signaling is required to maintain an AER phenotype. Misexpression of En1 at moderate levels specifically in the dorsal AER of transgenic mice was found to produce dorsally shifted AER fragments, whereas high levels of En1 abolished AER formation. In both cases, the dorsal gene Wnt7a was repressed in cells adjacent to the En1-expressing cells, demonstrating that signaling regulated by EN1 occurs across the D/V border. Finally, fate mapping of AER domains in these mutants showed that En1 plays a part in positioning and maintaining the two lineage borders.
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Affiliation(s)
- R A Kimmel
- Department of Cell Biology, New York University School of Medicine, New York, New York 10016 USA
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Kimmel RA, Turnbull DH, Blanquet V, Wurst W, Loomis CA, Joyner AL. Two lineage boundaries coordinate vertebrate apical ectodermal ridge formation. Genes Dev 2000. [DOI: 10.1101/gad.14.11.1377] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Proximal–distal outgrowth of the vertebrate limb bud is regulated by the apical ectodermal ridge (AER), which forms at an invariant position along the dorsal–ventral (D/V) axis of the embryo. We have studied the genetic and cellular events that regulate AER formation in the mouse. In contrast to implications from previous studies in chick, we identified two distinct lineage boundaries in mouse ectoderm prior to limb bud outgrowth using a Cre/loxP-based fate-mapping approach and a novel retroviral cell-labeling technique. One border is transient and at the limit of expression of the ventral gene En1, which corresponds to the D/V midline of the AER, and the second border corresponds to the dorsal AER margin. Labeling of AER precursors using an inducible Cre showed that not all cells that initially express AER genes form the AER, indicating that signaling is required to maintain an AER phenotype. Misexpression of En1 at moderate levels specifically in the dorsal AER of transgenic mice was found to produce dorsally shifted AER fragments, whereas high levels ofEn1 abolished AER formation. In both cases, the dorsal geneWnt7a was repressed in cells adjacent to theEn1-expressing cells, demonstrating that signaling regulated by EN1 occurs across the D/V border. Finally, fate mapping of AER domains in these mutants showed that En1 plays a part in positioning and maintaining the two lineage borders.
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Kimmel RA, Turnbull DH, Blanquet V, Wurst W, Loomis CA, Joyner AL. ABSTRACT Two lineage boundaries and <I>En1</I> coordinate AER formation. Biochem Cell Biol 2000. [DOI: 10.1139/bcb-78-5-644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Loomis CA, Kimmel RA, Tong CX, Michaud J, Joyner AL. Analysis of the genetic pathway leading to formation of ectopic apical ectodermal ridges in mouse Engrailed-1 mutant limbs. Development 1998; 125:1137-48. [PMID: 9463360 DOI: 10.1242/dev.125.6.1137] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The apical ectodermal ridge (AER), a rim of thickened ectodermal cells at the interface between the dorsal and ventral domains of the limb bud, is required for limb outgrowth and patterning. We have previously shown that the limbs of En1 mutant mice display dorsal-ventral and proximal-distal abnormalities, the latter being reflected in the appearance of a broadened AER and formation of ectopic ventral digits. A detailed genetic analysis of wild-type, En1 and Wnt7a mutant limb buds during AER development has delineated a role for En1 in normal AER formation. Our studies support previous suggestions that AER maturation involves the compression of an early broad ventral domain of limb ectoderm into a narrow rim at the tip and further show that En1 plays a critical role in the compaction phase. Loss of En1 leads to a delay in the distal shift and stratification of cells in the ventral half of the AER. At later stages, this often leads to development of a secondary ventral AER, which can promote formation of an ectopic digit. The second AER forms at the juxtaposition of the ventral border of the broadened mutant AER and the distal border of an ectopic Lmx1b expression domain. Analysis of En1/Wnt7a double mutants demonstrates that the dorsalizing gene Wnt7a is required for the formation of the ectopic AERs in En1 mutants and for ectopic expression of Lmx1b in the ventral mesenchyme. We suggest a model whereby, in En1 mutants, ectopic ventral Wnt7a and/or Lmx1b expression leads to the transformation of ventral cells in the broadened AER to a more dorsal phenotype. This leads to induction of a second zone of compaction ventrally, which in some cases goes on to form an autonomous secondary AER.
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Affiliation(s)
- C A Loomis
- Ronald O. Perelman Department of Dermatology, NYU Medical School, New York, NY 10016, USA.
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