1
|
Kowalkowski A, Zaremba KM, Rogers AP, Hoffman OR, Turco AE, Nichol PF. Lack of discreet colocalization of epithelial apoptosis to the atretic precursor in the colon of the Fibroblast growth factor receptor 2IIIb mouse and staining consistent with cellular movement suggest a revised model of atresia formation. Dev Dyn 2020; 249:741-753. [PMID: 32100913 DOI: 10.1002/dvdy.164] [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: 09/10/2018] [Revised: 12/30/2019] [Accepted: 01/27/2020] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Colonic atresias in the Fibroblast growth factor receptor 2IIIb (Fgfr2IIIb) mouse model have been attributed to increased epithelial apoptosis and decreased epithelial proliferation at embryonic day (E) 10.5. We therefore hypothesized that these processes would colocalize to the distal colon where atresias occur (atretic precursor) and would be excluded or minimized from the proximal colon and small intestine. RESULTS We observed a global increase in intestinal epithelial apoptosis in Fgfr2IIIb -/- intestines from E9.5 to E10.5 that did not colocalize to the atretic precursor. Additionally, epithelial proliferations rates in Fgfr2IIIb -/- intestines were statistically indistinguishable to that of controls at E10.5 and E11.5. At E11.5 distal colonic epithelial cells in mutants failed to assume the expected pseudostratified columnar architecture and the continuity of the adjacent basal lamina was disrupted. Individual E-cadherin-positive cells were observed in the colonic mesenchyme. CONCLUSIONS Our observations suggest that alterations in proliferation and apoptosis alone are insufficient to account for intestinal atresias and that these defects may arise from both a failure of distal colonic epithelial cells to develop normally and local disruptions in basal lamina architecture.
Collapse
Affiliation(s)
- Anna Kowalkowski
- Surgery Department, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Andrew P Rogers
- Surgery Department, University of Wisconsin, Madison, Wisconsin, USA
| | - Olivia R Hoffman
- Surgery Department, University of Wisconsin, Madison, Wisconsin, USA
| | - Anne E Turco
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA
| | - Peter F Nichol
- Surgery Department, University of Wisconsin, Madison, Wisconsin, USA
| |
Collapse
|
2
|
Baxter M, Voronkov M, Poolman T, Galli G, Pinali C, Goosey L, Knight A, Krakowiak K, Maidstone R, Iqbal M, Zi M, Prehar S, Cartwright EJ, Gibbs J, Matthews LC, Adamson AD, Humphreys NE, Rebelo-Guiomar P, Minczuk M, Bechtold DA, Loudon A, Ray D. Cardiac mitochondrial function depends on BUD23 mediated ribosome programming. eLife 2020; 9:e50705. [PMID: 31939735 PMCID: PMC7002040 DOI: 10.7554/elife.50705] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/24/2019] [Indexed: 01/21/2023] Open
Abstract
Efficient mitochondrial function is required in tissues with high energy demand such as the heart, and mitochondrial dysfunction is associated with cardiovascular disease. Expression of mitochondrial proteins is tightly regulated in response to internal and external stimuli. Here we identify a novel mechanism regulating mitochondrial content and function, through BUD23-dependent ribosome generation. BUD23 was required for ribosome maturation, normal 18S/28S stoichiometry and modulated the translation of mitochondrial transcripts in human A549 cells. Deletion of Bud23 in murine cardiomyocytes reduced mitochondrial content and function, leading to severe cardiomyopathy and death. We discovered that BUD23 selectively promotes ribosomal interaction with low GC-content 5'UTRs. Taken together we identify a critical role for BUD23 in bioenergetics gene expression, by promoting efficient translation of mRNA transcripts with low 5'UTR GC content. BUD23 emerges as essential to mouse development, and to postnatal cardiac function.
Collapse
Affiliation(s)
- Matthew Baxter
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
- Oxford Centre for Diabetes, Endocrinology and MetabolismUniversity of OxfordOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUnited Kingdom
| | - Maria Voronkov
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
- Oxford Centre for Diabetes, Endocrinology and MetabolismUniversity of OxfordOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUnited Kingdom
| | - Toryn Poolman
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
- Oxford Centre for Diabetes, Endocrinology and MetabolismUniversity of OxfordOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUnited Kingdom
| | - Gina Galli
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Christian Pinali
- Division of Cardiovascular SciencesUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Laurence Goosey
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Abigail Knight
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Karolina Krakowiak
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Robert Maidstone
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
- Oxford Centre for Diabetes, Endocrinology and MetabolismUniversity of OxfordOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUnited Kingdom
| | - Mudassar Iqbal
- Division of Cardiovascular SciencesUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Min Zi
- Division of Cardiovascular SciencesUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Sukhpal Prehar
- Division of Cardiovascular SciencesUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular SciencesUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Julie Gibbs
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Laura C Matthews
- Leeds Institute of Medical ResearchFaculty of Medicine and Health, University of LeedsLeedsUnited Kingdom
| | - Antony D Adamson
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Neil E Humphreys
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Pedro Rebelo-Guiomar
- Graduate Program in Areas of Basic and Applied Biology (GABBA)University of PortoPortoPortugal
- Medical Research Council Mitochondrial Biology UnitUniversity of CambridgeCambridgeUnited Kingdom
| | - Michal Minczuk
- Medical Research Council Mitochondrial Biology UnitUniversity of CambridgeCambridgeUnited Kingdom
| | - David A Bechtold
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - Andrew Loudon
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
| | - David Ray
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUnited Kingdom
- Oxford Centre for Diabetes, Endocrinology and MetabolismUniversity of OxfordOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreJohn Radcliffe HospitalOxfordUnited Kingdom
| |
Collapse
|
3
|
Wu YJ, Tejero R, Arancillo M, Vardar G, Korotkova T, Kintscher M, Schmitz D, Ponomarenko A, Tabares L, Rosenmund C. Syntaxin 1B is important for mouse postnatal survival and proper synaptic function at the mouse neuromuscular junctions. J Neurophysiol 2015. [PMID: 26203110 DOI: 10.1152/jn.00577.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
STX1 is a major neuronal syntaxin protein located at the plasma membrane of the neuronal tissues. Rodent STX1 has two highly similar paralogs, STX1A and STX1B, that are thought to be functionally redundant. Interestingly, some studies have shown that the distribution patterns of STX1A and STX1B at the central and peripheral nervous systems only partially overlapped, implying that there might be differential functions between these paralogs. In the current study, we generated an STX1B knockout (KO) mouse line and studied the impact of STX1B removal in neurons of several brain regions and the neuromuscular junction (NMJ). We found that either complete removal of STX1B or selective removal of it from forebrain excitatory neurons in mice caused premature death. Autaptic hippocampal and striatal cultures derived from STX1B KO mice still maintained efficient neurotransmission compared with neurons from STX1B wild-type and heterozygous mice. Interestingly, examining high-density cerebellar cultures revealed a decrease in the spontaneous GABAergic transmission frequency, which was most likely due to a lower number of neurons in the STX1B KO cultures, suggesting that STX1B is essential for neuronal survival in vitro. Moreover, our study also demonstrated that although STX1B is dispensable for the formation of the mouse NMJ, it is required to maintain the efficiency of neurotransmission at the nerve-muscle synapse.
Collapse
Affiliation(s)
- Yuan-Ju Wu
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Seville, Spain; and
| | - Marife Arancillo
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Gülcin Vardar
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Tatiana Korotkova
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany; Leibniz Institute for Molecular Pharmacology, Berlin, Germany
| | - Michael Kintscher
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Dietmar Schmitz
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Alexey Ponomarenko
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany; Leibniz Institute for Molecular Pharmacology, Berlin, Germany
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Seville, Spain; and
| | - Christian Rosenmund
- NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany;
| |
Collapse
|
4
|
Smeets CJLM, Jezierska J, Watanabe H, Duarri A, Fokkens MR, Meijer M, Zhou Q, Yakovleva T, Boddeke E, den Dunnen W, van Deursen J, Bakalkin G, Kampinga HH, van de Sluis B, Verbeek DS. Elevated mutant dynorphin A causes Purkinje cell loss and motor dysfunction in spinocerebellar ataxia type 23. Brain 2015; 138:2537-52. [PMID: 26169942 DOI: 10.1093/brain/awv195] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/27/2015] [Indexed: 12/30/2022] Open
Abstract
Spinocerebellar ataxia type 23 is caused by mutations in PDYN, which encodes the opioid neuropeptide precursor protein, prodynorphin. Prodynorphin is processed into the opioid peptides, α-neoendorphin, and dynorphins A and B, that normally exhibit opioid-receptor mediated actions in pain signalling and addiction. Dynorphin A is likely a mutational hotspot for spinocerebellar ataxia type 23 mutations, and in vitro data suggested that dynorphin A mutations lead to persistently elevated mutant peptide levels that are cytotoxic and may thus play a crucial role in the pathogenesis of spinocerebellar ataxia type 23. To further test this and study spinocerebellar ataxia type 23 in more detail, we generated a mouse carrying the spinocerebellar ataxia type 23 mutation R212W in PDYN. Analysis of peptide levels using a radioimmunoassay shows that these PDYN(R212W) mice display markedly elevated levels of mutant dynorphin A, which are associated with climber fibre retraction and Purkinje cell loss, visualized with immunohistochemical stainings. The PDYN(R212W) mice reproduced many of the clinical features of spinocerebellar ataxia type 23, with gait deficits starting at 3 months of age revealed by footprint pattern analysis, and progressive loss of motor coordination and balance at the age of 12 months demonstrated by declining performances on the accelerating Rotarod. The pathologically elevated mutant dynorphin A levels in the cerebellum coincided with transcriptionally dysregulated ionotropic and metabotropic glutamate receptors and glutamate transporters, and altered neuronal excitability. In conclusion, the PDYN(R212W) mouse is the first animal model of spinocerebellar ataxia type 23 and our work indicates that the elevated mutant dynorphin A peptide levels are likely responsible for the initiation and progression of the disease, affecting glutamatergic signalling, neuronal excitability, and motor performance. Our novel mouse model defines a critical role for opioid neuropeptides in spinocerebellar ataxia, and suggests that restoring the elevated mutant neuropeptide levels can be explored as a therapeutic intervention.
Collapse
Affiliation(s)
- Cleo J L M Smeets
- 1 Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Justyna Jezierska
- 1 Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Hiroyuki Watanabe
- 2 Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Anna Duarri
- 1 Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Michiel R Fokkens
- 1 Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Michel Meijer
- 3 Department of Medical Physiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Qin Zhou
- 2 Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Tania Yakovleva
- 2 Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Erik Boddeke
- 3 Department of Medical Physiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Wilfred den Dunnen
- 4 Department of Pathology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Jan van Deursen
- 5 Department of Paediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Georgy Bakalkin
- 3 Department of Medical Physiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Harm H Kampinga
- 6 Department of Cell Biology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Bart van de Sluis
- 7 Department of Paediatrics, Molecular Genetics Section, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- 1 Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| |
Collapse
|
5
|
Zaremba KM, Reeder AL, Kowalkowski A, Girma E, Nichol PF. Utility and limits of Hprt-Cre technology in generating mutant mouse embryos. J Surg Res 2014; 187:386-93. [PMID: 24360120 PMCID: PMC3959277 DOI: 10.1016/j.jss.2013.10.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Hprt-Cre doubles the prevalence of homozygous null embryos per litter versus heterozygous breedings without decreasing litter size. Resulting mutant embryos are genotypically and phenotypically equivalent between strategies. We set out to confirm the effectiveness of this approach with other alleles and hypothesized that it would increase efficiency in generating compound mutants. MATERIALS AND METHODS Null mutants for Cyp26b1, Pitx2, and Shh were generated with Hprt-Cre from conditional alleles as were double and triple allelic combinations of Fgfr2IIIb, Raldh2, and Cyp26b1. Embryos were genotyped and phenotyped by whole mount photography, histology, and immunohistochemistry. RESULTS Fifty percent of Hprt-Cre litters were homozygous null for Cyp26b1 (15/29) and Pitx2 (75/143), with phenotypic and genotypic equivalence to mutants from standard heterozygous breedings. In multi-allele breedings, mutant embryos constituted half of litters without significant embryo loss. In contrast, Shh breedings yielded a smaller ratio of embryos carrying two recombined alleles (6 of 16), with a significant litter size reduction because of early embryonic lethality (16 live embryos from 38 deciduae). CONCLUSIONS Hprt-Cre can be used to efficiently generate large numbers of mutant embryos with a number of alleles. Compound mutant generation was equally efficient. However, efficiency is reduced for genes whose protein product potentially interacts with the Hprt pathway (e.g., Shh).
Collapse
Affiliation(s)
- Krzysztof M Zaremba
- Division of Pediatric Surgery, Department of Surgery, University of Wisconsin SMPH Madison, Madison, Wisconsin
| | - Amy L Reeder
- Division of Pediatric Surgery, Department of Surgery, University of Wisconsin SMPH Madison, Madison, Wisconsin
| | - Anna Kowalkowski
- Division of Pediatric Surgery, Department of Surgery, University of Wisconsin SMPH Madison, Madison, Wisconsin
| | - Eden Girma
- Division of Pediatric Surgery, Department of Surgery, University of Wisconsin SMPH Madison, Madison, Wisconsin
| | - Peter F Nichol
- Division of Pediatric Surgery, Department of Surgery, University of Wisconsin SMPH Madison, Madison, Wisconsin.
| |
Collapse
|
6
|
Exogenous Sonic hedgehog protein does not rescue cultured intestine from atresia formation. J Surg Res 2013; 187:14-8. [PMID: 24393341 DOI: 10.1016/j.jss.2013.11.1114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 10/23/2013] [Accepted: 11/27/2013] [Indexed: 11/21/2022]
Abstract
BACKGROUND The mechanism of intestinal atresia formation remains undefined. Atresia in fibroblast growth factor receptor 2IIIb (Fgfr2IIIb(-/-)) mutant mouse embryos is preceded by endodermal apoptosis and involution of the surrounding mesoderm. We have observed that involution of the atretic segment is preceded by the downregulation of Sonic hedgehog (SHH) in the endoderm, which is a critical organizer of the intestinal mesoderm. We hypothesized that supplementation of Fgfr2IIIb(-/-) intestinal tracts with exogenous SHH protein before atresia formation would prevent involution of the mesoderm and rescue normal intestinal development. METHODS In situ hybridization was performed on control and Fgfr2IIIb(-/-) intestinal tracts for Shh or forkhead box protein F1 (FoxF1) between embryonic (E) day 11.5 and E12.0. Control and Fgfr2IIIb(-/-) intestinal tracts were harvested at E10.5 and cultured in media supplemented with fibroblast growth factor (FGF) 10 + SHH, or FGF10 with a SHH-coated bead. In situ hybridization was performed at E12.5 for Foxf1. RESULTS SHH and Foxf1 expression were downregulated during intestinal atresia formation. Media containing exogenous FGF10 + SHH did not prevent colonic atresia formation (involution). A SHH protein point source bead did induce Foxf1 expression in controls and mutants. CONCLUSIONS Shh and Foxf1 expression are disrupted in atresia formation of distal colon, thereby serving as potential markers of atretic events. Application of exogenous SHH (in media supplement or as a point source bead) is sufficient to induce Foxf1 expression, but insufficient to rescue development of distal colonic mesoderm in Fgfr2IIIb(-/-) mutant embryos. Shh signal disruption is not the critical mechanism by which loss of Fgfr2IIIb function results in atresia formation.
Collapse
|
7
|
Reeder AL, Botham RA, Zaremba KM, Nichol PF. Haploinsufficiency of retinaldehyde dehydrogenase 2 decreases the severity and incidence of duodenal atresia in the fibroblast growth factor receptor 2IIIb-/- mouse model. Surgery 2012; 152:768-75; discussion 775-6. [PMID: 23021139 DOI: 10.1016/j.surg.2012.07.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/13/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Homozygous null mutation of the fibroblast growth factor receptor 2IIIb (Fgfr2IIIb) gene in mice results in 42% of embryos developing duodenal atresias. Retinaldehyde dehydrogenase 2 (Raldh2, a gene critical for the generation of retinoic acid) is expressed in the mouse duodenum during the temporal window when duodenal atresias form. Raldh2 is critical for the normal development of the pancreatoduodenal region; therefore, we were interested in the effect of a Raldh2 mutation on duodenal atresia formation. To test this, we rendered Fgfr2IIIb(-/-) embryos haploinsufficient for the Raldh2 and examined these embryos for the incidence and severity of duodenal atresia. METHODS Control embryos, Fgfr2IIIb(-/-) mutants, and Fgfr2IIIb(-/-); Raldh2(+/-) mutants were harvested at embryonic day 18.5, genotyped, and fixed overnight. Intestinal tracts were isolated. The type and severity of duodenal atresia was documented. RESULTS A total of 97 Fgfr2IIIb(-/-) embryos were studied; 44 had duodenal atresias, and 41 of these presented as type III. In the 70 Fgfr2IIIb(-/-); Raldh2(+/-) embryos studied, a lesser incidence of duodenal atresia was seen (15 of 70; P = .0017; Fisher exact test). Atresia severity was also decreased; there were 12 embryos with type I atresias, 3 with type II atresias, and 0 with type III atresias (P < 2.81E-013; Fisher exact test). CONCLUSION Haploinsufficiency of Raldh2 decreases the incidence and severity of duodenal atresia in the Fgfr2IIIb(-/-) model. The ability to alter defect severity through manipulation of a single gene in a specific genetic background has potentially important implications for understanding the mechanisms by which intestinal atresias arise.
Collapse
Affiliation(s)
- Amy L Reeder
- Department of Surgery, Section of Pediatric Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | | | | |
Collapse
|
8
|
Formation of duodenal atresias in fibroblast growth factor receptor 2IIIb-/- mouse embryos occurs in the absence of an endodermal plug. J Pediatr Surg 2012; 47:1369-79. [PMID: 22813799 PMCID: PMC3401378 DOI: 10.1016/j.jpedsurg.2012.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 02/01/2012] [Accepted: 02/01/2012] [Indexed: 11/22/2022]
Abstract
PURPOSE Duodenal atresia in humans has been hypothesized to arise from a failure of the duodenal lumen to recanalize after formation of an endodermal plug. Recently, mutations in the fibroblast growth factor receptor 2 gene (Fgfr2IIIb) have been shown to cause atretic defects of the duodenum in mice. However, work in rats suggests that murine species do not form an endodermal plug during normal duodenal development. These lines of data led us to hypothesize that mice are able to form a duodenal atresia in the absence of an endodermal plug. To test this hypothesis, we examined duodenal development in wild-type and Fgfr2IIIb-/- embryos. METHODS Paraffin sections were generated for H&E, E-cadherin, or terminal deoxynucleotidyl transferase-mediated X-dUTP nick end labeling staining from Fgfr2IIIb-/- and wild-type embryos between embryonic days (E) 10.5 and E14.5. Sections were photographed and reconstructed into 3-dimensional display using Adobe Photoshop and Amira Visage software. RESULTS Normal mouse duodenum does not form an endodermal plug, although a plug does form in the pyloric region of the stomach at E14.5. Fgfr2IIIb-/- embryos experience significant apoptosis in the duodenal region at E10.5, followed by the disappearance of the endoderm in the atretic precursor by E11.5. Thereafter, the mesoderm of the atretic precursor involutes over the next 2 days in the absence of further apoptosis. Interestingly, an endodermal plug was not observed at any point during the formation of a duodenal atresia. CONCLUSIONS These results suggest that duodenal atresia in the Fgfr2IIIb-/- model does not arise from persistence of an epithelial plug. Rather it appears to result from the loss of the endoderm because of apoptosis very early in development.
Collapse
|
9
|
Reeder AL, Botham RA, Franco M, Zaremba KM, Nichol PF. Formation of intestinal atresias in the Fgfr2IIIb-/- mice is not associated with defects in notochord development or alterations in Shh expression. J Surg Res 2012; 177:139-45. [PMID: 22572615 DOI: 10.1016/j.jss.2012.04.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 03/24/2012] [Accepted: 04/11/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE The etiology of intestinal atresia remains elusive but has been ascribed to a number of possible events including in utero vascular accidents, failure of recanalization of the intestinal lumen, and mechanical compression. Another such event that has been postulated to be a cause in atresia formation is disruption in notochord development. This hypothesis arose from clinical observations of notochord abnormalities in patients with intestinal atresias as well as abnormal notochord development observed in a pharmacologic animal model of intestinal atresia. Atresias in this model result from in utero exposure to Adriamycin, wherein notochord defects were noted in up to 80% of embryos that manifested intestinal atresias. Embryos with notochord abnormalities were observed to have ectopic expression of Sonic Hedgehog (Shh), which in turn was postulated to be causative in atresia formation. We were interested in determining whether disruptions in notochord development or Shh expression occurred in an established genetic model of intestinal atresia and used the fibroblast growth factor receptor 2IIIb homozygous mutant (Fgfr2IIIb-/-) mouse model. These embryos develop colonic atresias (100% penetrance) and duodenal atresias (42% penetrance). METHODS Wild-type and Fgfr2IIIb-/- mouse embryos were harvested at embryonic day (E) 10.5, E11.5, E12.5, and E13.5. Whole-mount in situ hybridization was performed on E10.5 embryos for Shh. Embryos at each time point were harvested and sectioned for hematoxylin-eosin staining. Sections were photographed specifically for the notochord and resulting images reconstructed in 3-D using Amira software. Colons were isolated from wild-type and Fgfr2IIIb-/- embryos at E10.5, then cultured for 48 hours in Matrigel with FGF10 in the presence or absence of exogenous Shh protein. Explants were harvested, fixed in formalin, and photographed. RESULTS Fgfr2IIIb-/- mouse embryos exhibit no disruptions in Shh expression at E10.5, when the first events in atresia formation are known to occur. Three-dimensional reconstructions failed to demonstrate any anatomical disruptions in the notochord by discontinuity or excessive branching. Culture of wild-type intestines in the presence of Shh failed to induce atresia formation in either the duodenum or colon. Cultured Fgfr2IIIb-/- intestines developed atresias of the colon in either the presence or absence of Shh protein. CONCLUSIONS Although disruptions in notochord development can be associated with intestinal atresia formation, in the Fgfr2IIIb-/- genetic animal model neither disruptions in notochord development nor the presence of exogenous Shh protein are causative in the formation of these defects.
Collapse
Affiliation(s)
- Amy L Reeder
- University of Wisconsin SMPH-Department of Surgery, Section of Pediatric Surgery, Madison, Wisconsin 53792, USA
| | | | | | | | | |
Collapse
|