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Maden M, Polvadore T. Retinoic Acid-Induced Limb Duplications. Methods Mol Biol 2023; 2562:249-258. [PMID: 36272081 DOI: 10.1007/978-1-0716-2659-7_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Retinoic acid (RA) and the family of molecules based on vitamin A known as retinoids have remarkable effects on limb regeneration in salamanders and newts and cause whole limb duplications in a concentration-dependent manner. They respecify all three axes of the limb-the proximodistal, the anteroposterior, and the dorsoventral axis. As a result, complete limbs can be induced to regenerate from distal amputation planes producing two limbs in tandem. Here, we describe the basic methods for undertaking these experiments as well as the use of new synthetic retinoids which have retinoic acid receptor-selective actions. These will be valuable tools in future studies on the molecular basis of limb duplications and thus our understanding of the nature of positional information in the regenerating salamander limb.
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Affiliation(s)
- Malcolm Maden
- Department of Biology & UF Genetics Institute, University of Florida, Gainesville, FL, USA.
| | - Trey Polvadore
- Department of Biology & UF Genetics Institute, University of Florida, Gainesville, FL, USA
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Abstract
This chapter brings together data on the role of retinoic acid (RA) in the embryonic development of fins in zebrafish , limbs in amphibians , chicks , and mice, and regeneration of the amphibian limb . The intention is to determine whether there is a common set of principles by which we can understand the mode of action of RA in both embryos and adults. What emerges from this synthesis is that there are indeed commonalities in the involvement of RA in processes that ventralize, posteriorize, and proximalize the developing and regenerating limb . Different axes of the limb have historically been studied independently; as for example, the embryonic development of the anteroposterior (AP) axis of the chick limb bud versus the regeneration of the limb bud proximodistal (PD) axis . But when we take a broader view, a unifying principle emerges that explains why RA administration to embryos and regenerating limbs results in the development of multiple limbs in both cases. As might be expected, different molecular pathways govern the development of different systems and model organisms, but despite these differences, the pathways involve similar RA signaling genes, such as tbx5, meis, shh, fgfs and hox genes. Studies of developing and regenerating systems have highlighted that RA acts by being synthesized in one embryonic location while acting in another one, exactly as embryonic morphogens do, although there is no evidence for the presence of an RA gradient within the limb . What also emerges is that there is a paucity of information on the involvement of RA in development of the dorsoventral (DV) axis . A molecular explanation as to how RA establishes and alters positional information in all three axes is the most important area of study for the future.
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Lehoczky JA, Thomas PE, Patrie KM, Owens KM, Villarreal LM, Galbraith K, Washburn J, Johnson CN, Gavino B, Borowsky AD, Millen KJ, Wakenight P, Law W, Van Keuren ML, Gavrilina G, Hughes ED, Saunders TL, Brihn L, Nadeau JH, Innis JW. A novel intergenic ETnII-β insertion mutation causes multiple malformations in polypodia mice. PLoS Genet 2013; 9:e1003967. [PMID: 24339789 PMCID: PMC3854779 DOI: 10.1371/journal.pgen.1003967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 10/04/2013] [Indexed: 11/28/2022] Open
Abstract
Mouse early transposon insertions are responsible for ∼10% of spontaneous mutant phenotypes. We previously reported the phenotypes and genetic mapping of Polypodia, (Ppd), a spontaneous, X-linked dominant mutation with profound effects on body plan morphogenesis. Our new data shows that mutant mice are not born in expected Mendelian ratios secondary to loss after E9.5. In addition, we refined the Ppd genetic interval and discovered a novel ETnII-β early transposon insertion between the genes for Dusp9 and Pnck. The ETn inserted 1.6 kb downstream and antisense to Dusp9 and does not disrupt polyadenylation or splicing of either gene. Knock-in mice engineered to carry the ETn display Ppd characteristic ectopic caudal limb phenotypes, showing that the ETn insertion is the Ppd molecular lesion. Early transposons are actively expressed in the early blastocyst. To explore the consequences of the ETn on the genomic landscape at an early stage of development, we compared interval gene expression between wild-type and mutant ES cells. Mutant ES cell expression analysis revealed marked upregulation of Dusp9 mRNA and protein expression. Evaluation of the 5′ LTR CpG methylation state in adult mice revealed no correlation with the occurrence or severity of Ppd phenotypes at birth. Thus, the broad range of phenotypes observed in this mutant is secondary to a novel intergenic ETn insertion whose effects include dysregulation of nearby interval gene expression at early stages of development. Mobile genetic elements, particularly early transposons (ETn), cause malformations by inserting within genes leading to disruption of exons, splicing or polyadenylation. Few mutagenic early transposon insertions have been found outside genes and the effects of such insertions on surrounding gene regulation is poorly understood. We discovered a novel intergenic ETnII-β insertion in the mouse mutant Polypodia (Ppd). We reproduced the mutant phenotype after engineering the mutation in wild-type cells with homologous recombination, proving that this early transposon insertion is Ppd. Mutant mice are not born in expected Mendelian ratios secondary to loss after E9.5. Embryonic stem cells from mutant mice show upregulated transcription of an adjacent gene, Dusp9. Thus, at an early and critical stage of development, dysregulated gene transcription is one consequence of the insertion mutation. DNA methylation of the ETn 5′ LTR is not correlated with phenotypic outcome in mutant mice. Polypodia is an example of an intergenic mobile element insertion in mice causing dramatic morphogenetic defects and fetal death.
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Affiliation(s)
- Jessica A. Lehoczky
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peedikayil E. Thomas
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- Pediatrics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kevin M. Patrie
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kailey M. Owens
- Pediatrics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lisa M. Villarreal
- Pediatrics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kenneth Galbraith
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Joe Washburn
- Biomedical Research Core Facilities, DNA Sequencing Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Craig N. Johnson
- Biomedical Research Core Facilities, DNA Sequencing Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bryant Gavino
- Murine Molecular Constructs Laboratory-MMCL Mouse Biology Program, University of California, Davis, California, United States of America
| | - Alexander D. Borowsky
- University of California, Davis, Center for Comparative Medicine and Comprehensive Cancer Center, Department of Pathology and Laboratory Medicine, Davis, California, United States of America
| | - Kathleen J. Millen
- Division of Genetic Medicine, Department of Pediatrics, Seattle Children's Hospital, Seattle, Washington, United States of America
| | - Paul Wakenight
- Division of Genetic Medicine, Department of Pediatrics, Seattle Children's Hospital, Seattle, Washington, United States of America
| | - William Law
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Margaret L. Van Keuren
- Transgenic Animal Model Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Galina Gavrilina
- Transgenic Animal Model Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Elizabeth D. Hughes
- Transgenic Animal Model Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Thomas L. Saunders
- Transgenic Animal Model Core Lab, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lesil Brihn
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Joseph H. Nadeau
- Pacific Northwest Research Institute, Seattle, Washington, United States of America
| | - Jeffrey W. Innis
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- Pediatrics, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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