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Neal SJ, Rajasekaran A, Jusić N, Taylor L, Read M, Alfandari D, Pignoni F, Moody SA. Using Xenopus to discover new candidate genes involved in BOR and other congenital hearing loss syndromes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:212-240. [PMID: 37830236 PMCID: PMC11014897 DOI: 10.1002/jez.b.23222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/15/2023] [Accepted: 09/14/2023] [Indexed: 10/14/2023]
Abstract
Hearing in infants is essential for brain development, acquisition of verbal language skills, and development of social interactions. Therefore, it is important to diagnose hearing loss soon after birth so that interventions can be provided as early as possible. Most newborns in the United States are screened for hearing deficits and commercially available next-generation sequencing hearing loss panels often can identify the causative gene, which may also identify congenital defects in other organs. One of the most prevalent autosomal dominant congenital hearing loss syndromes is branchio-oto-renal syndrome (BOR), which also presents with defects in craniofacial structures and the kidney. Currently, mutations in three genes, SIX1, SIX5, and EYA1, are known to be causative in about half of the BOR patients that have been tested. To uncover new candidate genes that could be added to congenital hearing loss genetic screens, we have combined the power of Drosophila mutants and protein biochemical assays with the embryological advantages of Xenopus, a key aquatic animal model with a high level of genomic similarity to human, to identify potential Six1 transcriptional targets and interacting proteins that play a role during otic development. We review our transcriptomic, yeast 2-hybrid, and proteomic approaches that have revealed a large number of new candidates. We also discuss how we have begun to identify how Six1 and co-factors interact to direct developmental events necessary for normal otic development.
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Affiliation(s)
- Scott J. Neal
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, USA
| | - Anindita Rajasekaran
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, USA
| | - Nisveta Jusić
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, USA
| | - Louis Taylor
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Mai Read
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Dominique Alfandari
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Francesca Pignoni
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, USA
| | - Sally A. Moody
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
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Marchak A, Neilson KM, Majumdar HD, Yamauchi K, Klein SL, Moody SA. The sulfotransferase XB5850668.L is required to apportion embryonic ectodermal domains. Dev Dyn 2023; 252:1407-1427. [PMID: 37597164 PMCID: PMC10842325 DOI: 10.1002/dvdy.648] [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] [Revised: 06/08/2023] [Accepted: 07/26/2023] [Indexed: 08/21/2023] Open
Abstract
BACKGROUND Members of the sulfotransferase superfamily (SULT) influence the activity of a wide range of hormones, neurotransmitters, metabolites and xenobiotics. However, their roles in developmental processes are not well characterized even though they are expressed during embryogenesis. We previously found in a microarray screen that Six1 up-regulates LOC100037047, which encodes XB5850668.L, an uncharacterized sulfotransferase. RESULTS Since Six1 is required for patterning the embryonic ectoderm into its neural plate, neural crest, preplacodal and epidermal domains, we used loss- and gain-of function assays to characterize the role of XB5850668.L during this process. Knockdown of endogenous XB5850668.L resulted in the reduction of epidermal, neural crest, cranial placode and otic vesicle gene expression domains, concomitant with neural plate expansion. Increased levels had minimal effects, but infrequently expanded neural plate and neural crest gene domains, and infrequently reduced cranial placode and otic vesicle gene domains. Mutation of two key amino acids in the sulfotransferase catalytic domain required for PAPS binding and enzymatic activity tended to reduce the effects of overexpressing the wild-type protein. CONCLUSIONS Our analyses indicates that XB5850668.L is a member of the SULT2 family that plays important roles in patterning the embryonic ectoderm. Some aspects of its influence likely depend on sulfotransferase activity.
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Affiliation(s)
- Alexander Marchak
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Karen M Neilson
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Himani D Majumdar
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Kiyoshi Yamauchi
- Department of Biological Science, Shizuoka University, Shizuoka, Japan
| | - Steven L Klein
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
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Baxi AB, Nemes P, Moody SA. Time-resolved quantitative proteomic analysis of the developing Xenopus otic vesicle reveals putative congenital hearing loss candidates. iScience 2023; 26:107665. [PMID: 37670778 PMCID: PMC10475516 DOI: 10.1016/j.isci.2023.107665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/16/2023] [Accepted: 08/14/2023] [Indexed: 09/07/2023] Open
Abstract
Over 200 genes are known to underlie human congenital hearing loss (CHL). Although transcriptomic approaches have identified candidate regulators of otic development, little is known about the abundance of their protein products. We used a multiplexed quantitative mass spectrometry-based proteomic approach to determine protein abundances over key stages of Xenopus otic morphogenesis to reveal a dynamic expression of cytoskeletal, integrin signaling, and extracellular matrix proteins. We correlated these dynamically expressed proteins to previously published lists of putative downstream targets of human syndromic hearing loss genes: SIX1 (BOR syndrome), CHD7 (CHARGE syndrome), and SOX10 (Waardenburg syndrome). We identified transforming growth factor beta-induced (Tgfbi), an extracellular integrin-interacting protein, as a putative target of Six1 that is required for normal otic vesicle formation. Our findings demonstrate the application of this Xenopus dataset to understanding the dynamic regulation of proteins during otic development and to discovery of additional candidates for human CHL.
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Affiliation(s)
- Aparna B. Baxi
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
| | - Peter Nemes
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Sally A. Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
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Klein SL, Tavares ALP, Peterson M, Sullivan CH, Moody SA. Repressive Interactions Between Transcription Factors Separate Different Embryonic Ectodermal Domains. Front Cell Dev Biol 2022; 10:786052. [PMID: 35198557 PMCID: PMC8859430 DOI: 10.3389/fcell.2022.786052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
The embryonic ectoderm is composed of four domains: neural plate, neural crest, pre-placodal region (PPR) and epidermis. Their formation is initiated during early gastrulation by dorsal-ventral and anterior-posterior gradients of signaling factors that first divide the embryonic ectoderm into neural and non-neural domains. Next, the neural crest and PPR domains arise, either via differential competence of the neural and non-neural ectoderm (binary competence model) or via interactions between the neural and non-neural ectoderm tissues to produce an intermediate neural border zone (NB) (border state model) that subsequently separates into neural crest and PPR. Many previous gain- and loss-of-function experiments demonstrate that numerous TFs are expressed in initially overlapping zones that gradually resolve into patterns that by late neurula stages are characteristic of each of the four domains. Several of these studies suggested that this is accomplished by a combination of repressive TF interactions and competence to respond to local signals. In this study, we ectopically expressed TFs that at neural plate stages are characteristic of one domain in a different domain to test whether they act cell autonomously as repressors. We found that almost all tested TFs caused reduced expression of the other TFs. At gastrulation these effects were strictly within the lineage-labeled cells, indicating that the effects were cell autonomous, i.e., due to TF interactions within individual cells. Analysis of previously published single cell RNAseq datasets showed that at the end of gastrulation, and continuing to neural tube closure stages, many ectodermal cells express TFs characteristic of more than one neural plate stage domain, indicating that different TFs have the opportunity to interact within the same cell. At neurula stages repression was observed both in the lineage-labeled cells and in adjacent cells not bearing detectable lineage label, suggesting that cell-to-cell signaling has begun to contribute to the separation of the domains. Together, these observations directly demonstrate previous suggestions in the literature that the segregation of embryonic ectodermal domains initially involves cell autonomous, repressive TF interactions within an individual cell followed by the subsequent advent of non-cell autonomous signaling to neighbors.
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Affiliation(s)
- Steven L Klein
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, D.C., DC, United States
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, D.C., DC, United States
| | - Meredith Peterson
- Department of Biology, State College, Penn State University, University Park, PA, United States
| | | | - Sally A Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, D.C., DC, United States
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5
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Coppenrath K, Tavares ALP, Shaidani NI, Wlizla M, Moody SA, Horb M. Generation of a new six1-null line in Xenopus tropicalis for study of development and congenital disease. Genesis 2021; 59:e23453. [PMID: 34664392 DOI: 10.1002/dvg.23453] [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: 08/05/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 12/15/2022]
Abstract
The vertebrate Six (Sine oculis homeobox) family of homeodomain transcription factors plays critical roles in the development of several organs. Six1 plays a central role in cranial placode development, including the precursor tissues of the inner ear, as well as other cranial sensory organs and the kidney. In humans, mutations in SIX1 underlie some cases of Branchio-oto-renal (BOR) syndrome, which is characterized by moderate-to-severe hearing loss. We utilized CRISPR/Cas9 technology to establish a six1 mutant line in Xenopus tropicalis that is available to the research community. We demonstrate that at larval stages, the six1-null animals show severe disruptions in gene expression of putative Six1 target genes in the otic vesicle, cranial ganglia, branchial arch, and neural tube. At tadpole stages, six1-null animals display dysmorphic Meckel's, ceratohyal, and otic capsule cartilage morphology. This mutant line will be of value for the study of the development of several organs as well as congenital syndromes that involve these tissues.
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Affiliation(s)
- Kelsey Coppenrath
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, Massachusetts, USA
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Nikko-Ideen Shaidani
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, Massachusetts, USA
| | - Marcin Wlizla
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, Massachusetts, USA.,Embryology Department, Charles River Laboratories, Wilmington, Massachusetts, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Marko Horb
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, Massachusetts, USA
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Mutations in SIX1 Associated with Branchio-oto-Renal Syndrome (BOR) Differentially Affect Otic Expression of Putative Target Genes. J Dev Biol 2021; 9:jdb9030025. [PMID: 34208995 PMCID: PMC8293042 DOI: 10.3390/jdb9030025] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/16/2021] [Accepted: 06/26/2021] [Indexed: 12/12/2022] Open
Abstract
Several single-nucleotide mutations in SIX1 underlie branchio-otic/branchio-oto-renal (BOR) syndrome, but the clinical literature has not been able to correlate different variants with specific phenotypes. We previously assessed whether variants in either the cofactor binding domain (V17E, R110W) or the DNA binding domain (W122R, Y129C) might differentially affect early embryonic gene expression, and found that each variant had a different combination of effects on neural crest and placode gene expression. Since the otic vesicle gives rise to the inner ear, which is consistently affected in BOR, herein we focused on whether the variants differentially affected the otic expression of genes previously found to be likely Six1 targets. We found that V17E, which does not bind Eya cofactors, was as effective as wild-type Six1 in reducing most otic target genes, whereas R110W, W122R and Y129C, which bind Eya, were significantly less effective. Notably, V17E reduced the otic expression of prdm1, whereas R110W, W122R and Y129C expanded it. Since each mutant has defective transcriptional activity but differs in their ability to interact with Eya cofactors, we propose that altered cofactor interactions at the mutated sites differentially interfere with their ability to drive otic gene expression, and these differences may contribute to patient phenotype variability.
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Shah AM, Krohn P, Baxi AB, Tavares ALP, Sullivan CH, Chillakuru YR, Majumdar HD, Neilson KM, Moody SA. Six1 proteins with human branchio-oto-renal mutations differentially affect cranial gene expression and otic development. Dis Model Mech 2020; 13:dmm043489. [PMID: 31980437 PMCID: PMC7063838 DOI: 10.1242/dmm.043489] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/14/2020] [Indexed: 12/15/2022] Open
Abstract
Single-nucleotide mutations in human SIX1 result in amino acid substitutions in either the protein-protein interaction domain or the homeodomain, and cause ∼4% of branchio-otic (BOS) and branchio-oto-renal (BOR) cases. The phenotypic variation between patients with the same mutation, even within affected members of the same family, make it difficult to functionally distinguish between the different SIX1 mutations. We made four of the BOS/BOR substitutions in the Xenopus Six1 protein (V17E, R110W, W122R, Y129C), which is 100% identical to human in both the protein-protein interaction domain and the homeodomain, and expressed them in embryos to determine whether they cause differential changes in early craniofacial gene expression, otic gene expression or otic morphology. We confirmed that, similar to the human mutants, all four mutant Xenopus Six1 proteins access the nucleus but are transcriptionally deficient. Analysis of craniofacial gene expression showed that each mutant causes specific, often different and highly variable disruptions in the size of the domains of neural border zone, neural crest and pre-placodal ectoderm genes. Each mutant also had differential effects on genes that pattern the otic vesicle. Assessment of the tadpole inner ear demonstrated that while the auditory and vestibular structures formed, the volume of the otic cartilaginous capsule, otoliths, lumen and a subset of the hair cell-containing sensory patches were reduced. This detailed description of the effects of BOS/BOR-associated SIX1 mutations in the embryo indicates that each causes subtle changes in gene expression in the embryonic ectoderm and otocyst, leading to inner ear morphological anomalies.
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Affiliation(s)
- Ankita M Shah
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Patrick Krohn
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
- Institute of Zoology, University of Hohenheim, Stuttgart 70599, Germany
| | - Aparna B Baxi
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Charles H Sullivan
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
- Department of Biology, Grinnell College, Grinnell, IA 50112, USA
| | - Yeshwant R Chillakuru
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Himani D Majumdar
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Karen M Neilson
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
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Paraiso KD, Blitz IL, Zhou JJ, Cho KWY. Morpholinos Do Not Elicit an Innate Immune Response during Early Xenopus Embryogenesis. Dev Cell 2020; 49:643-650.e3. [PMID: 31112700 DOI: 10.1016/j.devcel.2019.04.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/14/2019] [Accepted: 04/16/2019] [Indexed: 02/06/2023]
Abstract
It has recently been reported that a common side effect of translation-blocking morpholino antisense oligonucleotides is the induction of a set of innate immune response genes in Xenopus embryos and that splicing-blocking morpholinos lead to unexpected off-target mis-splicing events. Here, we present an analysis of all publicly available Xenopus RNA sequencing (RNA-seq) data in a reexamination of the effects of translation-blocking morpholinos on the innate immune response. Our analysis does not support the authors' general conclusion, which was based on a limited number of RNA-seq datasets. Moreover, the strong induction of an immune response appears to be specific to the tbxt/tbxt2 morpholinos. The more comprehensive study presented here indicates that using morpholinos for targeted gene knockdowns remains of considerable value for the rapid identification of gene function.
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Affiliation(s)
- Kitt D Paraiso
- Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Ira L Blitz
- Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Jeff J Zhou
- Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Ken W Y Cho
- Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA.
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Blackburn ATM, Miller RK. Modeling congenital kidney diseases in Xenopus laevis. Dis Model Mech 2019; 12:12/4/dmm038604. [PMID: 30967415 PMCID: PMC6505484 DOI: 10.1242/dmm.038604] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Congenital anomalies of the kidney and urinary tract (CAKUT) occur in ∼1/500 live births and are a leading cause of pediatric kidney failure. With an average wait time of 3-5 years for a kidney transplant, the need is high for the development of new strategies aimed at reducing the incidence of CAKUT and preserving renal function. Next-generation sequencing has uncovered a significant number of putative causal genes, but a simple and efficient model system to examine the function of CAKUT genes is needed. Xenopus laevis (frog) embryos are well-suited to model congenital kidney diseases and to explore the mechanisms that cause these developmental defects. Xenopus has many advantages for studying the kidney: the embryos develop externally and are easily manipulated with microinjections, they have a functional kidney in ∼2 days, and 79% of identified human disease genes have a verified ortholog in Xenopus. This facilitates high-throughput screening of candidate CAKUT-causing genes. In this Review, we present the similarities between Xenopus and mammalian kidneys, highlight studies of CAKUT-causing genes in Xenopus and describe how common kidney diseases have been modeled successfully in this model organism. Additionally, we discuss several molecular pathways associated with kidney disease that have been studied in Xenopus and demonstrate why it is a useful model for studying human kidney diseases. Summary: Understanding how congenital kidney diseases arise is imperative to their treatment. Using Xenopus as a model will aid in elucidating kidney development and congenital kidney diseases.
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Affiliation(s)
- Alexandria T M Blackburn
- Pediatric Research Center, Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center, Houston, TX 77030, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Genetics and Epigenetics, Houston, TX 77030, USA
| | - Rachel K Miller
- Pediatric Research Center, Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center, Houston, TX 77030, USA .,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Genetics and Epigenetics, Houston, TX 77030, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Biochemistry and Cell Biology Houston, Houston, TX 77030, USA.,Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Sullivan CH, Majumdar HD, Neilson KM, Moody SA. Six1 and Irx1 have reciprocal interactions during cranial placode and otic vesicle formation. Dev Biol 2019; 446:68-79. [PMID: 30529252 PMCID: PMC6349505 DOI: 10.1016/j.ydbio.2018.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 12/02/2018] [Accepted: 12/03/2018] [Indexed: 01/04/2023]
Abstract
The specialized sensory organs of the vertebrate head are derived from thickened patches of cells in the ectoderm called cranial sensory placodes. The developmental program that generates these placodes and the genes that are expressed during the process have been studied extensively in a number of animals, yet very little is known about how these genes regulate one another. We previously found via a microarray screen that Six1, a known transcriptional regulator of cranial placode fate, up-regulates Irx1 in ectodermal explants. In this study, we investigated the transcriptional relationship between Six1 and Irx1 and found that they reciprocally regulate each other throughout cranial placode and otic vesicle formation. Although Irx1 expression precedes that of Six1 in the neural border zone, its continued and appropriately patterned expression in the pre-placodal region (PPR) and otic vesicle requires Six1. At early PPR stages, Six1 expands the Irx1 domain, but this activity subsides over time and changes to a predominantly repressive effect. Likewise, Irx1 initially expands Six1 expression in the PPR, but later represses it. We also found that Irx1 and Sox11, a known direct target of Six1, reciprocally affect each other. This work demonstrates that the interactions between Six1 and Irx1 are continuous during PPR and placode development and their transcriptional effects on one another change over developmental time.
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Affiliation(s)
- Charles H Sullivan
- Department of Biology, Grinnell College, Grinnell, IA, 50112, USA; bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Himani D Majumdar
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Karen M Neilson
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Sally A Moody
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA.
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Priscilla R, Szaro BG. Comparisons of SOCS mRNA and protein levels in Xenopus provide insights into optic nerve regenerative success. Brain Res 2019; 1704:150-160. [PMID: 30315759 DOI: 10.1016/j.brainres.2018.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/23/2018] [Accepted: 10/09/2018] [Indexed: 01/21/2023]
Abstract
In vertebrates from fishes to mammals, optic nerve injury induces increased expression ofSuppressor of Cytokine Signaling 3(SOCS3) mRNA, a modulator of cytokine signaling that is known to inhibit CNS axon regeneration. Unlike amniotes, however, anamniotes successfully regenerate optic axons, despite this increase. To address this seeming paradox, we examined the SOCS3 response to optic nerve injury in the frog,Xenopus laevis, at both the mRNA and protein levels. Far from being only transiently induced, SOCS3 mRNA expression increased throughout regeneration in retinal ganglion cells, but immunostaining and Western blots indicated that this increase was reflected at the protein level in regenerating optic axons but not in ganglion cell bodies. Polysome profiling provided additional evidence that SOCS3 protein levels were regulated post-translationally by demonstrating that the mRNA was efficiently translated in the injured eye. In tumor cells, another member of theSOCS gene family,SOCS2, is known to mediate SOCS3 degradation by targeting it for proteasomal degradation. Unlike the SOCS2 response in mammalian optic nerve injury, SOCS2 expression increased inXenopusretinal ganglion cells after injury, at both the mRNA and protein levels; it was, however, largely absent from both uninjured and regenerating optic axons. We propose a similar degradation mechanism may be spatially restricted inXenopusto keep SOCS3 protein levels sufficiently in check within ganglion cell bodies, where SOCS3 would otherwise inhibit transcription of genes needed for regeneration, but allow them to rise within the axons, where SOCS3 has pro-regenerative effects.
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Affiliation(s)
- Rupa Priscilla
- Department of Biological Sciences and the Center for Neuroscience Research, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Ben G Szaro
- Department of Biological Sciences and the Center for Neuroscience Research, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA.
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Plouhinec JL, Medina-Ruiz S, Borday C, Bernard E, Vert JP, Eisen MB, Harland RM, Monsoro-Burq AH. A molecular atlas of the developing ectoderm defines neural, neural crest, placode, and nonneural progenitor identity in vertebrates. PLoS Biol 2017; 15:e2004045. [PMID: 29049289 PMCID: PMC5663519 DOI: 10.1371/journal.pbio.2004045] [Citation(s) in RCA: 37] [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: 12/16/2016] [Revised: 10/31/2017] [Accepted: 09/29/2017] [Indexed: 12/18/2022] Open
Abstract
During vertebrate neurulation, the embryonic ectoderm is patterned into lineage progenitors for neural plate, neural crest, placodes and epidermis. Here, we use Xenopus laevis embryos to analyze the spatial and temporal transcriptome of distinct ectodermal domains in the course of neurulation, during the establishment of cell lineages. In order to define the transcriptome of small groups of cells from a single germ layer and to retain spatial information, dorsal and ventral ectoderm was subdivided along the anterior-posterior and medial-lateral axes by microdissections. Principal component analysis on the transcriptomes of these ectoderm fragments primarily identifies embryonic axes and temporal dynamics. This provides a genetic code to define positional information of any ectoderm sample along the anterior-posterior and dorsal-ventral axes directly from its transcriptome. In parallel, we use nonnegative matrix factorization to predict enhanced gene expression maps onto early and mid-neurula embryos, and specific signatures for each ectoderm area. The clustering of spatial and temporal datasets allowed detection of multiple biologically relevant groups (e.g., Wnt signaling, neural crest development, sensory placode specification, ciliogenesis, germ layer specification). We provide an interactive network interface, EctoMap, for exploring synexpression relationships among genes expressed in the neurula, and suggest several strategies to use this comprehensive dataset to address questions in developmental biology as well as stem cell or cancer research. Vertebrate embryo germ layers become progressively regionalized by evolutionarily conserved molecular processes. Catching the early steps of this dynamic spatial cell diversification at the scale of the transcriptome was challenging, even with the advent of efficient RNA sequencing. We have microdissected complementary and defined areas of a single germ layer, the developing ectoderm, and explored how the transcriptome changes over time and space in the ectoderm during the differentiation of frog epidermis, neural plate, and neural crest. We have created EctoMap, a searchable interface using these regional transcriptomes, to predict the expression of the 31 thousand genes expressed in neurulae and their networks of co-expression, predictive of functional relationships. Through several examples, we illustrate how these data provide insights in development, cancer, evolution and stem cell biology.
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Affiliation(s)
- Jean-Louis Plouhinec
- Université Paris Sud, Université Paris Saclay, CNRS UMR 3347, INSERM U1021, Orsay, France
- Institut Curie Research Division, PSL Research University, CNRS UMR 3347, INSERM U1021, Orsay, France
- MINES ParisTech, PSL Research University, CBIO - Centre for Computational Biology, Paris, France
| | - Sofía Medina-Ruiz
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Caroline Borday
- Université Paris Sud, Université Paris Saclay, CNRS UMR 3347, INSERM U1021, Orsay, France
- Institut Curie Research Division, PSL Research University, CNRS UMR 3347, INSERM U1021, Orsay, France
| | - Elsa Bernard
- MINES ParisTech, PSL Research University, CBIO - Centre for Computational Biology, Paris, France
- Institut Curie, INSERM U900, Paris, France
- INSERM U900, Paris, France
| | - Jean-Philippe Vert
- MINES ParisTech, PSL Research University, CBIO - Centre for Computational Biology, Paris, France
- Institut Curie, INSERM U900, Paris, France
- INSERM U900, Paris, France
| | - Michael B. Eisen
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development Biology, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Richard M. Harland
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Anne H. Monsoro-Burq
- Université Paris Sud, Université Paris Saclay, CNRS UMR 3347, INSERM U1021, Orsay, France
- Institut Curie Research Division, PSL Research University, CNRS UMR 3347, INSERM U1021, Orsay, France
- Institut Universitaire de France, Paris, France
- * E-mail:
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Pearl E, Morrow S, Noble A, Lerebours A, Horb M, Guille M. An optimized method for cryogenic storage of Xenopus sperm to maximise the effectiveness of research using genetically altered frogs. Theriogenology 2017; 92:149-155. [PMID: 28237331 PMCID: PMC5340284 DOI: 10.1016/j.theriogenology.2017.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/26/2016] [Accepted: 01/04/2017] [Indexed: 02/06/2023]
Abstract
Cryogenic storage of sperm from genetically altered Xenopus improves cost effectiveness and animal welfare associated with their use in research; currently it is routine for X. tropicalis but not reliable for X. laevis. Here we compare directly the three published protocols for Xenopus sperm freeze-thaw and determine whether sperm storage temperature, method of testes maceration and delays in the freezing protocols affect successful fertilisation and embryo development in X. laevis. We conclude that the protocol is robust and that the variability observed in fertilisation rates is due to differences between individuals. We show that the embryos made from the frozen-thawed sperm are normal and that the adults they develop into are reproductively indistinguishable from others in the colony. This opens the way for using cryopreserved sperm to distribute dominant genetically altered (GA) lines, potentially saving travel-induced stress to the male frogs, reducing their numbers used and making Xenopus experiments more cost effective. Xenopus cryopreservation is robust using an optimized method. Success is dependent on the quality of animals from which the sperm are taken. Frozen sperm may now be used to distribute lines and wild-type male gametes around the world.
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Affiliation(s)
- Esther Pearl
- National Xenopus Resource, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Sean Morrow
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Anna Noble
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Adelaide Lerebours
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
| | - Marko Horb
- National Xenopus Resource, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Matthew Guille
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK.
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14
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Riddiford N, Schlosser G. Dissecting the pre-placodal transcriptome to reveal presumptive direct targets of Six1 and Eya1 in cranial placodes. eLife 2016; 5. [PMID: 27576864 PMCID: PMC5035141 DOI: 10.7554/elife.17666] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 08/29/2016] [Indexed: 11/13/2022] Open
Abstract
The pre-placodal ectoderm, marked by the expression of the transcription factor Six1 and its co-activator Eya1, develops into placodes and ultimately into many cranial sensory organs and ganglia. Using RNA-Seq in Xenopus laevis we screened for presumptive direct placodal target genes of Six1 and Eya1 by overexpressing hormone-inducible constructs of Six1 and Eya1 in pre-placodal explants, and blocking protein synthesis before hormone-inducing nuclear translocation of Six1 or Eya1. Comparing the transcriptome of explants with non-induced controls, we identified hundreds of novel Six1/Eya1 target genes with potentially important roles for placode development. Loss-of-function studies confirmed that target genes encoding known transcriptional regulators of progenitor fates (e.g. Sox2, Hes8) and neuronal/sensory differentiation (e.g. Ngn1, Atoh1, Pou4f1, Gfi1) require Six1 and Eya1 for their placodal expression. Our findings provide insights into the gene regulatory network regulating placodal neurogenesis downstream of Six1 and Eya1 suggesting new avenues of research into placode development and disease.
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Affiliation(s)
- Nick Riddiford
- School of Natural Sciences, National University of Ireland, Galway, Ireland.,Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland
| | - Gerhard Schlosser
- School of Natural Sciences, National University of Ireland, Galway, Ireland.,Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland
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15
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Lienkamp SS. Using Xenopus to study genetic kidney diseases. Semin Cell Dev Biol 2016; 51:117-24. [PMID: 26851624 DOI: 10.1016/j.semcdb.2016.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/01/2016] [Indexed: 10/22/2022]
Abstract
Modern sequencing technology is revolutionizing our knowledge of inherited kidney disease. However, the molecular role of genes affected by the rapidly rising number of identified mutations is lagging behind. Xenopus is a highly useful, but underutilized model organism with unique properties excellently suited to decipher the molecular mechanisms of kidney development and disease. The embryonic kidney (pronephros) can be manipulated on only one side of the animal and its formation observed directly through the translucent skin. The moderate evolutionary distance between Xenopus and humans is a huge advantage for studying basic principles of kidney development, but still allows us to analyze the function of disease related genes. Optogenetic manipulations and genome editing by CRISPR/Cas are exciting additions to the toolbox for disease modelling and will facilitate the use of Xenopus in translational research. Therefore, the future of Xenopus in kidney research is bright.
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Affiliation(s)
- Soeren S Lienkamp
- Renal Division, Department of Medicine, University of Freiburg Medical Center, Hugstetter Straße 55, 79106 Freiburg, Germany; Center for Biological Signaling Studies (BIOSS), Albertstraße 19, 79104 Freiburg, Germany.
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16
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Moody SA, Neilson KM, Kenyon KL, Alfandari D, Pignoni F. Using Xenopus to discover new genes involved in branchiootorenal spectrum disorders. Comp Biochem Physiol C Toxicol Pharmacol 2015; 178:16-24. [PMID: 26117063 PMCID: PMC4662879 DOI: 10.1016/j.cbpc.2015.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 12/14/2022]
Abstract
Congenital hearing loss is an important clinical problem because, without early intervention, affected children do not properly acquire language and consequently have difficulties developing social skills. Although most newborns in the US are screened for hearing deficits, even earlier diagnosis can be made with prenatal genetic screening. Genetic screening that identifies the relevant mutated gene can also warn about potential congenital defects in organs not related to hearing. We will discuss efforts to identify new candidate genes that underlie the Branchiootorenal spectrum disorders in which affected children have hearing deficits and are also at risk for kidney defects. Mutations in two genes, SIX1 and EYA1, have been identified in about half of the patients tested. To uncover new candidate genes, we have used the aquatic animal model, Xenopus laevis, to identify genes that are part of the developmental genetic pathway of Six1 during otic and kidney development. We have already identified a large number of potential Six1 transcriptional targets and candidate co-factor proteins that are expressed at the right time and in the correct tissues to interact with Six1 during development. We discuss the advantages of using this system for gene discovery in a human congenital hearing loss syndrome.
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Affiliation(s)
- Sally A Moody
- Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA.
| | - Karen M Neilson
- Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
| | - Kristy L Kenyon
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY, USA
| | - Dominique Alfandari
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Francesca Pignoni
- Department of Ophthalmology, Upstate Medical University, Syracuse, NY, USA
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17
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Whitfield TT. Development of the inner ear. Curr Opin Genet Dev 2015; 32:112-8. [DOI: 10.1016/j.gde.2015.02.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 02/04/2023]
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18
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Abstract
Cranial sensory placodes derive from discrete patches of the head ectoderm and give rise to numerous sensory structures. During gastrulation, a specialized "neural border zone" forms around the neural plate in response to interactions between the neural and nonneural ectoderm and signals from adjacent mesodermal and/or endodermal tissues. This zone subsequently gives rise to two distinct precursor populations of the peripheral nervous system: the neural crest and the preplacodal ectoderm (PPE). The PPE is a common field from which all cranial sensory placodes arise (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, otic). Members of the Six family of transcription factors are major regulators of PPE specification, in partnership with cofactor proteins such as Eya. Six gene activity also maintains tissue boundaries between the PPE, neural crest, and epidermis by repressing genes that specify the fates of those adjacent ectodermally derived domains. As the embryo acquires anterior-posterior identity, the PPE becomes transcriptionally regionalized, and it subsequently becomes subdivided into specific placodes with distinct developmental fates in response to signaling from adjacent tissues. Each placode is characterized by a unique transcriptional program that leads to the differentiation of highly specialized cells, such as neurosecretory cells, sensory receptor cells, chemosensory neurons, peripheral glia, and supporting cells. In this review, we summarize the transcriptional and signaling factors that regulate key steps of placode development, influence subsequent sensory neuron specification, and discuss what is known about mutations in some of the essential PPE genes that underlie human congenital syndromes.
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Affiliation(s)
- Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA; George Washington University Institute for Neuroscience, Washington, DC, USA.
| | - Anthony-Samuel LaMantia
- George Washington University Institute for Neuroscience, Washington, DC, USA; Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
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