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Favarolo MB, Revinski DR, Garavaglia MJ, López SL. Nodal and churchill1 position the expression of a notch ligand during Xenopus germ layer segregation. Life Sci Alliance 2022; 5:5/12/e202201693. [PMID: 36180230 PMCID: PMC9604498 DOI: 10.26508/lsa.202201693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/24/2022] Open
Abstract
Churchill and Nodal signaling, which participate in vertebrates’ germ layer induction, position a domain of Delta/Notch activity, which refines germ layer boundaries during frog gastrulation. In vertebrates, Nodal signaling plays a major role in endomesoderm induction, but germ layer delimitation is poorly understood. In avian embryos, the neural/mesoderm boundary is controlled by the transcription factor CHURCHILL1, presumably through the repressor ZEB2, but there is scarce knowledge about its role in other vertebrates. During amphibian gastrulation, Delta/Notch signaling refines germ layer boundaries in the marginal zone, but it is unknown the place this pathway occupies in the network comprising Churchill1 and Nodal. Here, we show that Xenopus churchill1 is expressed in the presumptive neuroectoderm at mid-blastula transition and during gastrulation, upregulates zeb2, prevents dll1 expression in the neuroectoderm, and favors neuroectoderm over endomesoderm development. Nodal signaling prevents dll1 expression in the endoderm but induces it in the presumptive mesoderm, from where it activates Notch1 and its target gene hes4 in the non-involuting marginal zone. We propose a model where Nodal and Churchill1 position Dll1/Notch1/Hes4 domains in the marginal zone, ensuring the delimitation between mesoderm and neuroectoderm.
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Affiliation(s)
- María Belén Favarolo
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología/1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Buenos Aires, Argentina.,CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Laboratorio de Embriología Molecular "Prof. Dr. Andrés E. Carrasco", Buenos Aires, Argentina
| | - Diego R Revinski
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología/1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Buenos Aires, Argentina.,CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Laboratorio de Embriología Molecular "Prof. Dr. Andrés E. Carrasco", Buenos Aires, Argentina
| | - Matías J Garavaglia
- Laboratorio de Bioinsumos, Instituto de Biotecnología, Universidad Nacional de Hurlingham, Buenos Aires, Argentina
| | - Silvia L López
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología/1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Buenos Aires, Argentina .,CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Laboratorio de Embriología Molecular "Prof. Dr. Andrés E. Carrasco", Buenos Aires, Argentina
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2
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Esmaeili M, Blythe SA, Tobias JW, Zhang K, Yang J, Klein PS. Chromatin accessibility and histone acetylation in the regulation of competence in early development. Dev Biol 2020; 462:20-35. [PMID: 32119833 PMCID: PMC7225061 DOI: 10.1016/j.ydbio.2020.02.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/29/2020] [Accepted: 02/25/2020] [Indexed: 02/06/2023]
Abstract
As development proceeds, inductive cues are interpreted by competent tissues in a spatially and temporally restricted manner. While key inductive signaling pathways within competent cells are well-described at a molecular level, the mechanisms by which tissues lose responsiveness to inductive signals are not well understood. Localized activation of Wnt signaling before zygotic gene activation in Xenopus laevis leads to dorsal development, but competence to induce dorsal genes in response to Wnts is lost by the late blastula stage. We hypothesize that loss of competence is mediated by changes in histone modifications leading to a loss of chromatin accessibility at the promoters of Wnt target genes. We use ATAC-seq to evaluate genome-wide changes in chromatin accessibility across several developmental stages. Based on overlap with p300 binding, we identify thousands of putative cis-regulatory elements at the gastrula stage, including sites that lose accessibility by the end of gastrulation and are enriched for pluripotency factor binding motifs. Dorsal Wnt target gene promoters are not accessible after the loss of competence in the early gastrula while genes involved in mesoderm and neural crest development maintain accessibility at their promoters. Inhibition of histone deacetylases increases acetylation at the promoters of dorsal Wnt target genes and extends competence for dorsal gene induction by Wnt signaling. Histone deacetylase inhibition, however, is not sufficient to extend competence for mesoderm or neural crest induction. These data suggest that chromatin state regulates the loss of competence to inductive signals in a context-dependent manner.
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Affiliation(s)
- Melody Esmaeili
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Shelby A Blythe
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - John W Tobias
- Penn Genomic Analysis Core and Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Kai Zhang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jing Yang
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
| | - Peter S Klein
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Departments of Medicine (Hematology-Oncology) and Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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3
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Xenopus SOX5 enhances myogenic transcription indirectly through transrepression. Dev Biol 2018; 442:262-275. [PMID: 30071218 DOI: 10.1016/j.ydbio.2018.07.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/16/2018] [Accepted: 07/28/2018] [Indexed: 02/06/2023]
Abstract
In anamniotes, somite compartimentalization in the lateral somitic domain leads simultaneously to myotome and dermomyotome formation. In the myotome, Xenopus Sox5 is co-expressed with Myod1 in the course of myogenic differentiation. Here, we studied the function of Sox5 using a Myod1-induced myogenic transcription assay in pluripotent cells of animal caps. We found that Sox5 enhances myogenic transcription of muscle markers Des, Actc1, Ckm and MyhE3. The use of chimeric transactivating or transrepressive Sox5 proteins indicates that Sox5 acts as a transrepressor and indirectly stimulates myogenic transcription except for the slow muscle-specific genes Myh7L, Myh7S, Myl2 and Tnnc1. We showed that this role is shared by Sox6, which is structurally similar to Sox5, both belonging to the SoxD subfamily of transcription factors. Moreover, Sox5 can antagonize the inhibitory function of Meox2 on myogenic differentiation. Meox2 which is a dermomyotome marker, represses myogenic transcription in Myod-induced myogenic transcription assay and in Nodal5-induced mesoderm from animal cap assay. The inhibitory function of Meox2 and the pro-myogenic function of Sox5 were confirmed during Xenopus normal development by the use of translation-blocking oligomorpholinos and dexamethasone inducible chimeric Sox5 and Meox2 proteins. We have therefore identified a new function for SoxD proteins in muscle cells, which can indirectly enhance myogenic transcription through transrepression, in addition to the previously identified function as a direct repressor of slow muscle-specific genes.
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4
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Row RH, Pegg A, Kinney BA, Farr GH, Maves L, Lowell S, Wilson V, Martin BL. BMP and FGF signaling interact to pattern mesoderm by controlling basic helix-loop-helix transcription factor activity. eLife 2018; 7:31018. [PMID: 29877796 PMCID: PMC6013256 DOI: 10.7554/elife.31018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 05/26/2018] [Indexed: 02/06/2023] Open
Abstract
The mesodermal germ layer is patterned into mediolateral subtypes by signaling factors including BMP and FGF. How these pathways are integrated to induce specific mediolateral cell fates is not well understood. We used mesoderm derived from post-gastrulation neuromesodermal progenitors (NMPs), which undergo a binary mediolateral patterning decision, as a simplified model to understand how FGF acts together with BMP to impart mediolateral fate. Using zebrafish and mouse NMPs, we identify an evolutionarily conserved mechanism of BMP and FGF-mediated mediolateral mesodermal patterning that occurs through modulation of basic helix-loop-helix (bHLH) transcription factor activity. BMP imparts lateral fate through induction of Id helix loop helix (HLH) proteins, which antagonize bHLH transcription factors, induced by FGF signaling, that specify medial fate. We extend our analysis of zebrafish development to show that bHLH activity is responsible for the mediolateral patterning of the entire mesodermal germ layer.
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Affiliation(s)
- Richard H Row
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
| | - Amy Pegg
- MRC Center for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Brian A Kinney
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
| | - Gist H Farr
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, United States
| | - Lisa Maves
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, United States.,Division of Cardiology, Department of Pediatrics, University of Washington, Seattle, United States
| | - Sally Lowell
- MRC Center for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Valerie Wilson
- MRC Center for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Benjamin L Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
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5
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Della Gaspera B, Armand AS, Lecolle S, Charbonnier F, Chanoine C. Mef2d acts upstream of muscle identity genes and couples lateral myogenesis to dermomyotome formation in Xenopus laevis. PLoS One 2012; 7:e52359. [PMID: 23300648 PMCID: PMC3534117 DOI: 10.1371/journal.pone.0052359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 11/15/2012] [Indexed: 11/18/2022] Open
Abstract
Xenopus myotome is formed by a first medial and lateral myogenesis directly arising from the presomitic mesoderm followed by a second myogenic wave emanating from the dermomyotome. Here, by a series of gain and loss of function experiments, we showed that Mef2d, a member of the Mef2 family of MADS-box transcription factors, appeared as an upstream regulator of lateral myogenesis, and as an inducer of dermomyotome formation at the beginning of neurulation. In the lateral presomitic cells, we showed that Mef2d transactivates Myod expression which is necessary for lateral myogenesis. In the most lateral cells of the presomitic mesoderm, we showed that Mef2d and Paraxis (Tcf15), a member of the Twist family of transcription factors, were co-localized and activate directly the expression of Meox2, which acts upstream of Pax3 expression during dermomyotome formation. Cell tracing experiments confirm that the most lateral Meox2 expressing cells of the presomitic mesoderm correspond to the dermomyotome progenitors since they give rise to the most dorsal cells of the somitic mesoderm. Thus, Xenopus Mef2d couples lateral myogenesis to dermomyotome formation before somite segmentation. These results together with our previous works reveal striking similarities between dermomyotome and tendon formation in Xenopus: both develop in association with myogenic cells and both involve a gene transactivation pathway where one member of the Mef2 family, Mef2d or Mef2c, cooperates with a bHLH protein of the Twist family, Paraxis or Scx (Scleraxis) respectively. We propose that these shared characteristics in Xenopus laevis reflect the existence of a vertebrate ancestral mechanism which has coupled the development of the myogenic cells to the formation of associated tissues during somite compartmentalization.
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Affiliation(s)
- Bruno Della Gaspera
- Centre d'Etude de la Sensori-Motricité, UMR 8194 CNRS, Université Paris Descartes, Centre Universitaire des Saints-Pères, Paris, France.
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6
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FGF signalling modulates transcriptional repression by Xenopus groucho-related-4. Biol Cell 2012; 101:301-8. [DOI: 10.1042/bc20080136] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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7
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Halperin-Barlev O, Kalcheim C. Sclerotome-derived Slit1 drives directional migration and differentiation of Robo2-expressing pioneer myoblasts. Development 2011; 138:2935-45. [PMID: 21653616 DOI: 10.1242/dev.065714] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pioneer myoblasts generate the first myotomal fibers and act as a scaffold to pattern further myotome development. From their origin in the medial epithelial somite, they dissociate and migrate towards the rostral edge of each somite, from which differentiation proceeds in both rostral-to-caudal and medial-to-lateral directions. The mechanisms underlying formation of this unique wave of pioneer myofibers remain unknown. We show that rostrocaudal or mediolateral somite inversions in avian embryos do not alter the original directions of pioneer myoblast migration and differentiation into fibers, demonstrating that regulation of pioneer patterning is somite-intrinsic. Furthermore, pioneer myoblasts express Robo2 downstream of MyoD and Myf5, whereas the dermomyotome and caudal sclerotome express Slit1. Loss of Robo2 or of sclerotome-derived Slit1 function perturbed both directional cell migration and fiber formation, and their effects were mediated through RhoA. Although myoblast specification was not affected, expression of the intermediate filament desmin was reduced. Hence, Slit1 and Robo2, via RhoA, act to pattern formation of the pioneer myotome through the regulation of cytoskeletal assembly.
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Affiliation(s)
- Osnat Halperin-Barlev
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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8
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Nentwich O, Dingwell KS, Nordheim A, Smith JC. Downstream of FGF during mesoderm formation in Xenopus: the roles of Elk-1 and Egr-1. Dev Biol 2009; 336:313-26. [PMID: 19799892 DOI: 10.1016/j.ydbio.2009.09.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 09/19/2009] [Accepted: 09/21/2009] [Indexed: 01/24/2023]
Abstract
Signalling by members of the FGF family is required for induction and maintenance of the mesoderm during amphibian development. One of the downstream effectors of FGF is the SRF-interacting Ets family member Elk-1, which, after phosphorylation by MAP kinase, activates the expression of immediate-early genes. Here, we show that Xenopus Elk-1 is phosphorylated in response to FGF signalling in a dynamic pattern throughout the embryo. Loss of XElk-1 function causes reduced expression of Xbra at neurula stages, followed by a failure to form notochord and muscle and then the partial loss of trunk structures. One of the genes regulated by XElk-1 is XEgr-1, which encodes a zinc finger transcription factor: we show that phosphorylated XElk-1 forms a complex with XSRF that binds to the XEgr-1 promoter. Superficially, Xenopus tropicalis embryos with reduced levels of XEgr-1 resemble those lacking XElk-1, but to our surprise, levels of Xbra are elevated at late gastrula stages in such embryos, and over-expression of XEgr-1 causes the down-regulation of Xbra both in whole embryos and in animal pole regions treated with activin or FGF. In contrast, the myogenic regulatory factor XMyoD is activated by XEgr-1 in a direct manner. We discuss these counterintuitive results in terms of the genetic regulatory network to which XEgr-1 contributes.
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Affiliation(s)
- Oliver Nentwich
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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9
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Lou X, Li S, Wang J, Ding X. Activin/nodal signaling modulates XPAPC expression during Xenopus gastrulation. Dev Dyn 2008; 237:683-91. [PMID: 18265000 DOI: 10.1002/dvdy.21456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Gastrulation is the first obligatory morphogenesis during vertebrate development, by which the body plan is established. Nodal signaling is a key player in many developmental processes, including gastrulation. XPAPC has been found to exert its biological function through modifying the adhesion property of cells and interacting with other several important molecules in embryos. In this report, we show that nodal signaling is necessary and sufficient for XPAPC expression during Xenopus gastrulation. Furthermore, we isolated 4.8 kb upstream DNA sequence of Xenopus XPAPC, and proved that this 4.8-kb genomic contig is sufficient to recapitulate the expression pattern of XPAPC from gastrula to tail bud stage. Transgene and ChIP assays indicate that Activin/nodal signaling participates in regulation of XPAPC expression through a Smad binding element within the XPAPC promoter. Concomitant investigation suggests that the canonical Wnt pathway-activated XPAPC expression requires nodal signaling.
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Affiliation(s)
- Xin Lou
- Key Laboratory of Stem Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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Morris SA, Almeida AD, Tanaka H, Ohta K, Ohnuma SI. Tsukushi modulates Xnr2, FGF and BMP signaling: regulation of Xenopus germ layer formation. PLoS One 2007; 2:e1004. [PMID: 17925852 PMCID: PMC1994590 DOI: 10.1371/journal.pone.0001004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 09/11/2007] [Indexed: 11/28/2022] Open
Abstract
Background Cell-cell communication is essential in tissue patterning. In early amphibian development, mesoderm is formed in the blastula-stage embryo through inductive interactions in which vegetal cells act on overlying equatorial cells. Members of the TGF-β family such as activin B, Vg1, derrière and Xenopus nodal-related proteins (Xnrs) are candidate mesoderm inducing factors, with further activity to induce endoderm of the vegetal region. TGF-β-like ligands, including BMP, are also responsible for patterning of germ layers. In addition, FGF signaling is essential for mesoderm formation whereas FGF signal inhibition has been implicated in endoderm induction. Clearly, several signaling pathways are coordinated to produce an appropriate developmental output; although intracellular crosstalk is known to integrate multiple pathways, relatively little is known about extracellular coordination. Methodology/Principal Findings Here, we show that Xenopus Tsukushi (X-TSK), a member of the secreted small leucine rich repeat proteoglycan (SLRP) family, is expressed in ectoderm, endoderm, and the organizer during early development. We have previously reported that X-TSK binds to and inhibits BMP signaling in cooperation with chordin. We now demonstrate two novel interactions: X-TSK binds to and inhibits signaling by FGF8b, in addition to binding to and enhancement of Xnr2 signaling. This signal integration by X-TSK at the extracellular level has an important role in germ layer formation and patterning. Vegetally localized X-TSK potentiates endoderm formation through coordination of BMP, FGF and Xnr2 signaling. In contrast, X-TSK inhibition of FGF-MAPK signaling blocks ventrolateral mesoderm formation, while BMP inhibition enhances organizer formation. These actions of X-TSK are reliant upon its expression in endoderm and dorsal mesoderm, with relative exclusion from ventrolateral mesoderm, in a pattern shaped by FGF signals. Conclusions/Significance Based on our observations, we propose a novel mechanism by which X-TSK refines the field of positional information by integration of multiple pathways in the extracellular space.
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Affiliation(s)
- Samantha A. Morris
- Department of Oncology, The Hutchison/Medical Research Council Research Centre, University of Cambridge, Cambridge, United Kingdom
- * To whom correspondence should be addressed. E-mail: (SM); (SO)
| | - Alexandra D. Almeida
- Department of Oncology, The Hutchison/Medical Research Council Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Hideaki Tanaka
- Department of Developmental Neurobiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kunimasa Ohta
- Department of Developmental Neurobiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Shin-ichi Ohnuma
- Department of Oncology, The Hutchison/Medical Research Council Research Centre, University of Cambridge, Cambridge, United Kingdom
- * To whom correspondence should be addressed. E-mail: (SM); (SO)
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11
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Gerhart J, Neely C, Elder J, Pfautz J, Perlman J, Narciso L, Linask KK, Knudsen K, George-Weinstein M. Cells that express MyoD mRNA in the epiblast are stably committed to the skeletal muscle lineage. ACTA ACUST UNITED AC 2007; 178:649-60. [PMID: 17698608 PMCID: PMC2064471 DOI: 10.1083/jcb.200703060] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The epiblast of the chick embryo contains cells that express MyoD mRNA but not MyoD protein. We investigated whether MyoD-positive (MyoDpos) epiblast cells are stably committed to the skeletal muscle lineage or whether their fate can be altered in different environments. A small number of MyoDpos epiblast cells were tracked into the heart and nervous system. In these locations, they expressed MyoD mRNA and some synthesized MyoD protein. No MyoDpos epiblast cells differentiated into cardiac muscle or neurons. Similar results were obtained when MyoDpos cells were isolated from the epiblast and microinjected into the precardiac mesoderm or neural plate. In contrast, epiblast cells lacking MyoD differentiated according to their environment. These results demonstrate that the epiblast contains both multipotent cells and a subpopulation of cells that are stably committed to the skeletal muscle lineage before the onset of gastrulation. Stable programming in the epiblast may ensure that MyoDpos cells express similar signaling molecules in a variety of environments.
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Affiliation(s)
- Jacquelyn Gerhart
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA 19131, USA
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12
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Kahane N, Ben-Yair R, Kalcheim C. Medial pioneer fibers pattern the morphogenesis of early myoblasts derived from the lateral somite. Dev Biol 2007; 305:439-50. [PMID: 17382923 DOI: 10.1016/j.ydbio.2007.02.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 02/11/2007] [Accepted: 02/21/2007] [Indexed: 10/23/2022]
Abstract
The first wave of myoblasts which constitutes the post-mitotic myotome stems from the medial epithelial somite. Whereas medial pioneers extend throughout the entire mediolateral myotome at cervical and limb levels, at flank regions they are complemented laterally by a population of early myoblasts emerging from the lateral epithelial somite. These myoblasts delaminate underneath the nascent dermomyotome and become post-mitotic. They are Myf5-positive but express MyoD and desmin only a day later while differentiating into fibers. Overexpression of Noggin in the lateral somite triggers their premature differentiation suggesting that lateral plate-BMP4 maintains them in an undifferentiated state. Moreover, directly accelerating their differentiation by MyoD overexpression prior to arrival of medial fibers, generates a severely mispatterned lateral myotome. This is in contrast to medial pioneers that have the capacity for self-organization. Furthermore, inhibiting differentiation of medial pioneers with dominant-negative MyoD also disrupts lateral myoblast patterning and differentiation. Thus, we propose that medial pioneers are needed for proper morphogenesis of the lateral population which is kept as undifferentiated mesenchyme by BMP4 until their arrival. In addition, medial pioneers also organize dermomyotome lip-derived fibers suggesting that they have a general role in patterning myotome development.
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Affiliation(s)
- Nitza Kahane
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel
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13
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Keenan ID, Sharrard RM, Isaacs HV. FGF signal transduction and the regulation of Cdx gene expression. Dev Biol 2006; 299:478-88. [PMID: 16982047 DOI: 10.1016/j.ydbio.2006.08.040] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Revised: 08/07/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
Cdx homeodomain transcription factors play important roles in the development of the vertebrate body axis and gut epithelium. Signaling involving FGF, wnt and retinoic acid ligands has been implicated in the regulation of individual Cdx genes. In this study we examine the requirement for FGF-dependent signal transduction pathways in the regulation of Cdx gene expression. In the amphibian Xenopus laevis the earliest expression of Cdx1, Cdx2 and Cdx4 is within the developing mesoderm. We show that a functional FGF signaling pathway is required for the normal expression of all three amphibian Cdx genes during gastrula stages. We show that FGF stimulation activates signaling through both the MAP kinase pathway and the PI-3 kinase pathway in Xenopus tissue explants. However, our analysis of these pathways in gastrula stage embryos indicates that the MAP kinase pathway is required for Cdx gene expression, whereas the PI-3 kinase pathway is not. We show that FGF and wnt signaling can interact in the regulation of Cdx genes and during gastrula stages the normal expression of the Cdx genes requires the activity of both pathways. Furthermore, we show that wnt mediated Cdx regulation is independent of the MAP kinase pathway.
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Affiliation(s)
- Iain D Keenan
- Department of Biology, University of York, York, YO10 5YW, UK
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14
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Chanoine C, Della Gaspera B, Charbonnier F. Myogenic regulatory factors: Redundant or specific functions? Lessons fromXenopus. Dev Dyn 2004; 231:662-70. [PMID: 15499556 DOI: 10.1002/dvdy.20174] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The discovery, in the late 1980s, of the MyoD gene family of muscle transcription factors has proved to be a milestone in understanding the molecular events controlling the specification and differentiation of the muscle lineage. From gene knock-out mice experiments progressively emerged the idea that each myogenic regulatory factor (MRF) has evolved a specialized as well as a redundant role in muscle differentiation. To date, MyoD serves as a paradigm for the MRF mode of function. The features of gene regulation by MyoD support a model in which subprograms of gene expression are achieved by the combination of promoter-specific regulation of MyoD binding and MyoD-mediated binding of various ancillary proteins. This binding likely includes site-specific chromatin reorganization by means of direct or indirect interaction with remodeling enzymes. In this cascade of molecular events leading to the proper and reproducible activation of muscle gene expression, the role and mode of function of other MRFs still remains largely unclear. Recent in vivo findings using the Xenopus embryo model strongly support the concept that a single MRF can specifically control a subset of muscle genes and, thus, can be substituted by other MRFs albeit with dramatically lower efficiency. The topic of this review is to summarize the molecular data accounting for a redundant and/or specific involvement of each member of the MyoD family in myogenesis in the light of recent studies on the Xenopus model.
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Affiliation(s)
- Christophe Chanoine
- UMR 7060 CNRS, Equipe Biologie du Développement et de la Différenciation Neuromusculaire, Centre Universitaire des Saints-Pères, Université René Descartes, Paris, France.
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15
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Chen Y, Lin GF, Hu R, Chen Y, Ding X. Activin/Nodal signals mediate the ventral expression of myf-5 in Xenopus gastrula embryos. Biochem Biophys Res Commun 2003; 310:121-7. [PMID: 14511658 DOI: 10.1016/j.bbrc.2003.08.127] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Expression of myf-5, a key component of myogenic regulatory genes, expands into the ventral marginal zone during Xenopus gastrulation after the dorsal activation takes place. Little is known about how this dynamic expression pattern occurs. Here, we provide evidences to suggest that Activin/Nodal signals participate in the regulation of ventral expression of Xmyf-5 in gastrula embryos. Two Smad binding elements (SBEs) within the Xenopus myf-5 promoter can specifically interact with Smad4 protein. Furthermore, we demonstrate that the two SBEs are both indispensable for conferring responsiveness to Activin/Nodal signals and to ventral expression of myf-5 in Xenopus gastrula embryos.
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Affiliation(s)
- Ying Chen
- Laboratory of Molecular and Cell biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, PR China
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16
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Charbonnier F, Della Gaspara B, Armand AS, Lécolle S, Launay T, Gallien CL, Chanoine C. Specific activation of the acetylcholine receptor subunit genes by MyoD family proteins. J Biol Chem 2003; 278:33169-74. [PMID: 12807909 DOI: 10.1074/jbc.m304744200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whether the myogenic regulatory factors (MRFs) of the MyoD family can discriminate among the muscle gene targets for the proper and reproducible formation of skeletal muscle is a recurrent question. We have previously shown that, in Xenopus laevis, myogenin specifically transactivated muscle structural genes in vivo. In the present study, we used the Xenopus model to examine the role of XMyoD, XMyf5, and XMRF4 for the transactivation of the (nicotinic acetylcholine receptor) nAChR genes in vivo. During early Xenopus development, the expression patterns of nAChR subunit genes proved to be correlated with the expression patterns of the MRFs. We show that XMyf5 specifically induced the expression of the delta-subunit gene in cap animal assays and in endoderm cells of Xenopus embryos but was unable to activate the expression of the gamma-subunit gene. In embryos, overexpression of a dominant-negative XMyf5 variant led to the repression of delta-but not gamma-subunit gene expression. Conversely, XMyoD and XMRF4 activated gamma-subunit gene expression but were unable to activate delta-subunit gene expression. Finally, all MRFs induced expression of the alpha-subunit gene. These findings strengthen the concept that one MRF can specifically control a subset of muscle genes that cannot be activated by the other MRFs.
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Affiliation(s)
- Frédéric Charbonnier
- UMR 7060 CNRS, Equipe Biologie du développement et de la Différenciation Neuromusculaire, Centre Universitaire des Saints-Pères, Université René Descartes, F-75270 Paris Cedex 06, France
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17
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Geng X, Xiao L, Lin GF, Hu R, Wang JH, Rupp RAW, Ding X. Lef/Tcf-dependent Wnt/beta-catenin signaling during Xenopus axis specification. FEBS Lett 2003; 547:1-6. [PMID: 12860376 DOI: 10.1016/s0014-5793(03)00639-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Though the Wnt/beta-catenin signaling pathway is known to play key roles during Xenopus axis specification, whether it signals exclusively through Lef/Tcf transcription factors in this process remains unclear. To investigate this issue, we generated transgenic frog embryos expressing green fluorescent protein (GFP) driven by a Lef/Tcf-dependent and Wnt/beta-catenin-responsive promoter. This promoter is highly sensitive and even detects maternal beta-catenin activity prior to the large-scale transcription of zygotic genes. Unexpectedly, GFP expression was observed only in some, but not all, known Wnt/beta-catenin-positive territories in Xenopus early development. Furthermore, ubiquitous expression of dominant Lef-1 protein variants from transgenes revealed that zygotic Lef/Tcf activity is required for the ventroposterior development of Xenopus embryos. In summary, our results suggest that endogenous Wnt/beta-catenin activity does not result in obligatory Lef/Tcf-dependent gene activation, and that the ventroposteriorizing activity of zygotic Wnt-8 signaling is mediated by Lef/Tcf proteins.
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Affiliation(s)
- Xin Geng
- Laboratory of Molecular and Cell Biology, Laboratory of Stem Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Yue-yang Road 320, 200031, Shanghai, PR China
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18
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Pownall ME, Gustafsson MK, Emerson CP. Myogenic regulatory factors and the specification of muscle progenitors in vertebrate embryos. Annu Rev Cell Dev Biol 2003; 18:747-83. [PMID: 12142270 DOI: 10.1146/annurev.cellbio.18.012502.105758] [Citation(s) in RCA: 415] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Embryological and genetic studies of mouse, bird, zebrafish, and frog embryos are providing new insights into the regulatory functions of the myogenic regulatory factors, MyoD, Myf5, Myogenin, and MRF4, and the transcriptional and signaling mechanisms that control their expression during the specification and differentiation of muscle progenitors. Myf5 and MyoD genes have genetically redundant, but developmentally distinct regulatory functions in the specification and the differentiation of somite and head muscle progenitor lineages. Myogenin and MRF4 have later functions in muscle differentiation, and Pax and Hox genes coordinate the migration and specification of somite progenitors at sites of hypaxial and limb muscle formation in the embryo body. Transcription enhancers that control Myf5 and MyoD activation in muscle progenitors and maintain their expression during muscle differentiation have been identified by transgenic analysis. In epaxial, hypaxial, limb, and head muscle progenitors, Myf5 is controlled by lineage-specific transcription enhancers, providing evidence that multiple mechanisms control progenitor specification at different sites of myogenesis in the embryo. Developmental signaling ligands and their signal transduction effectors function both interactively and independently to control Myf5 and MyoD activation in muscle progenitor lineages, likely through direct regulation of their transcription enhancers. Future investigations of the signaling and transcriptional mechanisms that control Myf5 and MyoD in the muscle progenitor lineages of different vertebrate embryos can be expected to provide a detailed understanding of the developmental and evolutionary mechanisms for anatomical muscles formation in vertebrates. This knowledge will be a foundation for development of stem cell therapies to repair diseased and damaged muscles.
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19
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Abstract
Xenopus myogenesis is characterized by specific features, different from those of mammalian and avian systems both at the cellular level and in gene expression patterns. During early embryogenesis, after the initial molecular signals inducing mesoderm, the myogenic determination factors XMyoD and XMyf-5 are activated in presomitic mesoderm in response to mesoderm-inducing factors. After these first inductions of the myogenic program, forming muscles in Xenopus can have different destinies, some of these resulting in cell death before adulthood. In particular, it is quite characteristic of this species that, during metamorphosis, the primary myotomal myofibers completely die and are progressively replaced by secondary "adult" multinucleated myofibers. This feature offers the unique opportunity to totally separate the molecular analysis of these two distinct types of myogenesis. The aim of this review is to summarize our knowledge on the cellular and molecular events as well as the epigenetic regulations involved in the construction of Xenopus muscles during development.
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Affiliation(s)
- Christophe Chanoine
- Laboratoire de Biologie du Développement et de la Différenciation Musculaire (LNRS UMR 7060 CNRS), Paris, France.
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20
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Vernon AE, Philpott A. A single cdk inhibitor, p27Xic1, functions beyond cell cycle regulation to promote muscle differentiation in Xenopus. Development 2003; 130:71-83. [PMID: 12441292 DOI: 10.1242/dev.00180] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular basis of the antagonism between cellular proliferation and differentiation is poorly understood. We have investigated the role of the cyclin-dependent kinase inhibitor p27(Xic1) in the co-ordination of cell cycle exit and differentiation during early myogenesis in vivo using Xenopus embryos. In this report, we demonstrate that p27(Xic1) is highly expressed in the developing myotome, that ablation of p27(Xic1) protein prevents muscle differentiation and that p27(Xic1) synergizes with the transcription factor MyoD to promote muscle differentiation. Furthermore, the ability of p27(Xic1) to promote myogenesis resides in an N-terminal domain and is separable from its cell cycle regulation function. This data demonstrates that a single cyclin-dependent kinase inhibitor, p27(Xic1), controls in vivo muscle differentiation in Xenopus and that regulation of this process by p27(Xic1) requires activities beyond cell cycle inhibition.
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Affiliation(s)
- Ann E Vernon
- Department of Oncology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2XY, UK
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21
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Lin GF, Geng X, Chen Y, Qu B, Wang F, Hu R, Ding X. T-box binding site mediates the dorsal activation of myf-5 in Xenopus gastrula embryos. Dev Dyn 2003; 226:51-8. [PMID: 12508224 DOI: 10.1002/dvdy.10215] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Myf-5, a member of the muscle regulatory factor family of transcription factors, plays an important role in the determination, development, and differentiation of the skeletal muscle. Factors that regulate the expression of myf-5 itself are not well understood. We show here that a T-box binding site in the Xenopus myf-5 promoter mediated the activation of myf-5 expression through specific interaction with nuclear proteins of gastrula embryos. The T-box binding site could be bound by and respond to T-box proteins. T-box genes could induce Xmyf-5. The results suggest that T-box proteins are involved in the specification of myogenic mesoderm and muscle development.
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Affiliation(s)
- Gu Fa Lin
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, People's Republic of China
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22
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Yang J, Mei W, Otto A, Xiao L, Tao Q, Geng X, Rupp RAW, Ding X. Repression through a distal TCF-3 binding site restricts Xenopus myf-5 expression in gastrula mesoderm. Mech Dev 2002; 115:79-89. [PMID: 12049769 DOI: 10.1016/s0925-4773(02)00121-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The development of skeletal muscle in the vertebrate embryo is controlled by a transcriptional cascade that includes the four myogenic regulatory factors Myf-5, MyoD, Myogenin, and MRF4. The dynamic expression pattern of myf-5 during myogenesis is thought to be consistent with its role during early determination of the myogenic lineage. To study the factors and mechanisms, which regulate myf-5 transcription in Xenopus, we isolated a genomic DNA clone containing 4858 bp of Xmyf-5 5' flanking region. Using a transgenic reporter assay, we show here that this genomic contig is sufficient to recapitulate the dynamic stage- and tissue-specific expression pattern of Xmyf-5 from the gastrula to tail bud stages. For the primary induction of myf-5 transcription, we identify three main regulatory elements, which are responsible for (i) activation in dorsal mesoderm, (ii) activation in ventral mesoderm, and (iii) repression in midline mesoderm, respectively. Their combined activities define the two-winged expression domain of myf-5 in the preinvoluted mesoderm. Repression in midline mesoderm is mediated by a single TCF binding site located in the 5' end of the -4.8 kbp sequence, which binds XTcf-3 protein in vitro. Endogenous Wnt signaling in the lateral mesoderm is required to overcome the long-range repression through this distal TCF site, and to stimulate myf-5 transcription independently from it. The element for ventral mesoderm activation responds to Activin. Together, these results describe a regulatory mosaic of repression and activation, which defines the myf-5 expression profile in the frog gastrula.
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Affiliation(s)
- Jing Yang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, PR China
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23
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Rupp RAW, Singhal N, Veenstra GJC. When the embryonic genome flexes its muscles. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:2294-9. [PMID: 11985611 DOI: 10.1046/j.1432-1033.2002.02885.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the development of multicellular organisms, both transient and stable gene expression patterns have to be established in a precisely orchestrated sequence. Evidence from diverse model organisms indicates that this epigenetic program involves not only transcription factors, but also the local structure, composition, and modification of chromatin, which define and maintain the accessibility and transcriptional competence of the nucleosomal DNA template. A paradigm for the interdependence of development and chromatin is constituted by the mechanisms controlling the specification and differentiation of the skeletal muscle cell lineage in vertebrates, which is the topic of this review.
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Affiliation(s)
- Ralph A W Rupp
- Adolf-Butenandt-Institut, Department of Molecular Biology, München, Germany.
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24
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Shi DL, Bourdelas A, Umbhauer M, Boucaut JC. Zygotic Wnt/beta-catenin signaling preferentially regulates the expression of Myf5 gene in the mesoderm of Xenopus. Dev Biol 2002; 245:124-35. [PMID: 11969260 DOI: 10.1006/dbio.2002.0633] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Zygotic Wnt signaling has been shown to be involved in dorsoventral mesodermal patterning in Xenopus embryos, but how it regulates different myogenic gene expression in the lateral mesodermal domains is not clear. Here, we use transient exposure of embryos or explants to lithium, which mimics Wnt/beta-catenin signaling, as a tool to regulate the activation of this pathway at different times and places during early development. We show that activation of Wnt/beta-catenin signaling at the early gastrula stage rapidly induces ectopic expression of XMyf5 in both the dorsal and ventral mesoderm. In situ hybridization analysis reveals that the induction of ectopic XMyf5 expression in the dorsal mesoderm occurs within 45 min and is not blocked by the protein synthesis inhibitor cycloheximide. By contrast, the induction of XMyoD is observed after 2 h of lithium treatment and the normal expression pattern of XMyoD is blocked by cycloheximide. Analysis by RT-PCR of ectodermal explants isolated soon after midblastula transition indicates that lithium also specifically induces XMyf5 expression, which takes place 30 min following lithium treatment and is not blocked by cycloheximide, arguing strongly for an immediate-early response. In the early gastrula, inhibition of Wnt/beta-catenin signaling blocks the expression of XMyf5 and XMyoD, but not of Xbra. We further show that zygotic Wnt/beta-catenin signaling interacts specifically with bFGF and eFGF to promote XMyf5 expression in ectodermal cells. These results suggest that Wnt/beta-catenin pathway is required for regulating myogenic gene expression in the presumptive mesoderm. In particular, it may directly activate the expression of the XMyf5 gene in the muscle precursor cells.
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Affiliation(s)
- De-Li Shi
- Groupe de Biologie Expérimentale, Laboratoire de Biologie du Développement, CNRS UMR 7622, Université Pierre et Marie Curie, 9 quai Saint-Bernard, 75005 Paris, France.
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25
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Fisher ME, Isaacs HV, Pownall ME. eFGF is required for activation of XmyoD expression in the myogenic cell lineage of Xenopus laevis. Development 2002; 129:1307-15. [PMID: 11880340 DOI: 10.1242/dev.129.6.1307] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This paper addresses the molecular mechanisms that regulate the transcriptional activation of the myogenic regulatory factor XmyoD in the skeletal muscle lineage of Xenopus laevis. Using antisense morpholino oligonucleotide-mediated inhibition, we show that the signalling molecule embryonic fibroblast growth factor (eFGF), which is the amphibian homologue of FGF4, is necessary for the initial activation of XmyoD transcription in myogenic cells. We demonstrate that eFGF can activate the expression of XmyoD in the absence of protein synthesis, indicating that this regulation is direct. Our data suggest that regulation of XmyoD expression may involve a labile transcriptional repressor. In addition, we show that eFGF is itself an immediate early response to activin, a molecule that mimics the endogenous mesoderm-inducing signal. We propose a model for the regulation of XmyoD within the early mesoderm, and discuss the relevance that these findings have for the understanding of myogenic specification in higher vertebrates.
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26
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Zetser A, Frank D, Bengal E. MAP kinase converts MyoD into an instructive muscle differentiation factor in Xenopus. Dev Biol 2001; 240:168-81. [PMID: 11784054 DOI: 10.1006/dbio.2001.0465] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In amphibian development, muscle is specified in the dorsal lateral marginal zone (DLMZ) of the gastrula embryo. Two critical events specify the formation of skeletal muscle: the expression of the myogenic transcription factor, XMyoD, and the secretion of bone morphogenetic protein (BMP) antagonists by the adjacent Spemann organizer. Inhibition of BMP signaling during early gastrula stages converts XMyoD protein into an instructive differentiation factor in the DLMZ. Yet, the intracellular signaling factors connecting BMP antagonism and activation of XMyoD remain unknown. Our data show that BMP antagonism induces the activity of mitogen-activated protein kinase (MAPK), and that the activity of MAPK is necessary for muscle-specific differentiation. Treatment of gastrula-stage DLMZ explants with MAPK pathway inhibitors ventralized mesoderm and prevented muscle differentiation. Expression of XMyoD in ventral mesoderm weakly induced muscle formation; however, the coexpression of a constitutively active MEK1 with XMyoD efficiently induced muscle differentiation. Activation of the MAPK pathway did not induce the transcription of XMyoD, but increased its protein levels and transcriptional activity. Thus, MAPK activation is subsequent to BMP antagonism, and participates in the dorsalization of mesoderm by converting the XMyoD protein into a potent differentiation factor.
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Affiliation(s)
- A Zetser
- Department of Biochemistry, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
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27
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Zhou M, Ouyang W, Gong Q, Katz SG, White JM, Orkin SH, Murphy KM. Friend of GATA-1 represses GATA-3-dependent activity in CD4+ T cells. J Exp Med 2001; 194:1461-71. [PMID: 11714753 PMCID: PMC2193678 DOI: 10.1084/jem.194.10.1461] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The development of naive CD4+ T cells into a T helper (Th) 2 subset capable of producing interleukin (IL)-4, IL-5, and IL-13 involves a signal transducer and activator of transcription (Stat)6-dependent induction of GATA-3 expression, followed by Stat6-independent GATA-3 autoactivation. The friend of GATA (FOG)-1 protein regulates GATA transcription factor activity in several stages of hematopoietic development including erythrocyte and megakaryocyte differentiation, but whether FOG-1 regulates GATA-3 in T cells is uncertain. We show that FOG-1 can repress GATA-3-dependent activation of the IL-5 promoter in T cells. Also, FOG-1 overexpression during primary activation of naive T cells inhibited Th2 development in CD4+ T cells. FOG-1 fully repressed GATA-3-dependent Th2 development and GATA-3 autoactivation, but not Stat6-dependent induction of GATA-3. FOG-1 overexpression repressed development of Th2 cells from naive T cells, but did not reverse the phenotype of fully committed Th2 cells. Thus, FOG-1 may be one factor capable of regulating the Th2 development.
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Affiliation(s)
- M Zhou
- Department of Pathology and Immunology, Department of Medicine, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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28
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Umbhauer M, Boucaut JC, Shi DL. Repression of XMyoD expression and myogenesis by Xhairy-1 in Xenopus early embryo. Mech Dev 2001; 109:61-8. [PMID: 11677053 DOI: 10.1016/s0925-4773(01)00517-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Activated Notch-Delta signalling was shown to inhibit myogenesis, but whether and how it regulates myogenic gene expression is not clear. We analyzed the implication of Xenopus hairy-1 (Xhairy-1), a member of the hairy and enhancer-of-split (E(spl)) family that may function as nuclear effector of Notch signalling pathway, in regulating XMyoD gene expression at the initial step of myogenesis. Xhairy-1 transcripts are expressed soon after mid-blastula transition and exhibits overlapping expression with Notch pathway genes such as Delta-1 in the posterior somitic mesoderm. We show that overexpression of Xhairy-1 blocks the expression of XMyoD in early gastrula ectodermal cells treated with the mesoderm-inducing factor activin, and in the mesoderm tissues of early embryos. It inhibits myogenesis and produces trunk defects at later stages. Xhairy-1 also inhibits the expression of the pan-mesodermal marker Xbra, but expression of other early mesoderm markers such as goosecoid and chordin is not affected. These effects require the basic helix-loop-helix (bHLH) domain, as well as a synergy between the central Orange domain and the C-terminus WRPW-Groucho-interacting domain. Furthermore, overexpression in ectodermal cells of Xhairy-1/VP16, in which Xhairy-1 repressor domain is replaced by the activator domain of the viral protein VP16, induces the expression of XMyoD in the absence of protein synthesis. Interestingly, Xhairy-1/VP16 does not induce the expression of Xbra and XMyf5 in the same condition. During neurulation, the expression of XMyoD induced by Xhairy-1/VP16 declines and the expression of muscle actin gene was never detected. These results suggest that Notch signalling through hairy-related genes may specifically regulate XMyoD expression at the initial step of myogenesis in vertebrates.
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Affiliation(s)
- M Umbhauer
- Groupe de Biologie Expérimentale, Laboratoire de Biologie du Développement, CNRS UMR 7622, Université Pierre et Marie Curie, 9 quai Saint-Bernard, 75005, Paris, France
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29
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Kiefer JC, Hauschka SD. Myf-5 is transiently expressed in nonmuscle mesoderm and exhibits dynamic regional changes within the presegmented mesoderm and somites I-IV. Dev Biol 2001; 232:77-90. [PMID: 11254349 DOI: 10.1006/dbio.2000.0114] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myf-5 is one of four myogenic regulatory factors that play important roles in skeletal muscle development. This study provides detailed analysis of Myf-5 expression during early chick development using an in situ hybridization technique that has been optimized to detect low level Myf-5 transcripts. This facilitated detection of heretofore unrecognized dynamic changes in Myf-5 expression patterns. Myf-5 expression is first detected at stage 3 in the primitive streak and exhibits transient low-level expression in nonmyogenic mesoderm. Myf-5 is later expressed in the presegmented mesoderm (psm) in a reiterating pattern that is coordinated with somitogenesis and also colocalizes with the Notch ligand C-Delta-1. In somites (S) I-IV, Myf-5 expression exhibits dynamic regional changes, and in somites rostral to S IV, Myf-5 is expressed at higher levels in muscle precursors in the dorsomedial somite. Semiquantitative comparison of Myf-5 mRNA levels in the psm and in myotome-containing somites indicates about a 10-fold difference. The expression pattern of Myf-5 differs from that of MyoD, which we find is expressed only in the dorsomedial somite. These data reveal that Myf-5 is expressed at low levels several stages before muscle differentiation occurs and suggest that only a subset of cells that initially express Myf-5 will upregulate its expression and differentiate as muscle.
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Affiliation(s)
- J C Kiefer
- Department of Biochemistry, University of Washington, Seattle, Washington, 98195, USA
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30
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Steinbac OC, Wolffe AP, Rupp RA. Histone deacetylase activity is required for the induction of the MyoD muscle cell lineage in Xenopus. Biol Chem 2000; 381:1013-6. [PMID: 11076034 DOI: 10.1515/bc.2000.124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Acetylation of nucleosome core histones, which is positively correlated with transcriptional activity, is developmentally regulated in Xenopus. Here we have used the specific histone deacetylase (HDAC)-inhibitor trichostatin A (TSA) to induce precocious histone hyperacetylation in the early frog embryo in order to investigate the potential role of the endogenous changes in chromatin acetylation for the temporally programmed induction of skeletal myogenesis. We show that TSA-treatment (i) selectively blocked the transcriptional induction of the myoD gene, and (ii) severely reduced subsequent muscle differentiation. Both phenotypes required TSA application before gastrulation. This indicates that HDAC activity is required early for the formation of the frog embryonic musculature, apparently for the induction of the MyoD-dependent muscle cell lineage.
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Affiliation(s)
- O C Steinbac
- Friedrich-Miescher-Laboratorium der Max-Planck-Gesellschaft, Tübingen, Germany
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31
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Brand T, Butler-Browne G, Füchtbauer EM, Renkawitz-Pohl R, Brand-Saberi B. EMBO Workshop Report: Molecular genetics of muscle development and neuromuscular diseases Kloster Irsee, Germany, September 26-October 1, 1999. EMBO J 2000; 19:1935-41. [PMID: 10790360 PMCID: PMC305694 DOI: 10.1093/emboj/19.9.1935] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- T Brand
- Department of Cell and Molecular Biology, Technical University of Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.
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32
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Offield MF, Hirsch N, Grainger RM. The development of Xenopus tropicalis transgenic lines and their use in studying lens developmental timing in living embryos. Development 2000; 127:1789-97. [PMID: 10751168 DOI: 10.1242/dev.127.9.1789] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The generation of reporter lines for observing lens differentiation in vivo demonstrates a new strategy for embryological manipulation and allows us to address a long-standing question concerning the timing of the onset of differentiation. Xenopus tropicalis was used to make GFP reporter lines with (gamma)1-crystallin promoter elements directing GFP expression within the early lens. X. tropicalis is a close relative of X. laevis that shares the same ease of tissue manipulation with the added benefits of a diploid genome and faster life cycle. The efficiency of the Xenopus transgenic technique was improved in order to generate greater numbers of normal, adult transgenic animals and to facilitate in vivo analysis of the crystallin promoter. This transgene is transmitted through the germline, providing an accurate and consistent way to monitor lens differentiation. This line permitted us to distinguish models for how the onset of differentiation is controlled: by a process intrinsic to differentiating tissue or one dependent on external cues. This experiment would not have been feasible without the sensitivity and accuracy provided by the in vivo reporter. We find that, in specified lens ectoderm transplanted from neural tube stage donors to younger neural-plate-stage hosts, the onset of differentiation, as measured by expression of the crystallin/GFP transgene, is delayed by an average of 4.4 hours. When specified lens ectoderm is explanted into culture, the delay was an average of 16.3 hours relative to control embryos. These data suggest that the onset of differentiation in specified ectoderm can be altered by the environment and imply that this onset is normally controlled by external cues rather than by an intrinsic mechanism.
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Affiliation(s)
- M F Offield
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA.
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Wittenberger T, Steinbach OC, Authaler A, Kopan R, Rupp RA. MyoD stimulates delta-1 transcription and triggers notch signaling in the Xenopus gastrula. EMBO J 1999; 18:1915-22. [PMID: 10202155 PMCID: PMC1171277 DOI: 10.1093/emboj/18.7.1915] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Notch signaling cascade is involved in many developmental decisions, a paradigm of which has been the selection between epidermal and neural cell fates in both invertebrates and vertebrates. Notch has also been implicated as a regulator of myogenesis, although its precise function there has remained controversial. Here we show that the muscle-determining factor MyoD is a direct, positive regulator of the Notch ligand Delta-1 in prospective myoblasts of the pre-involuted mesoderm in Xenopus gastrulae. Injection of a dominant MyoD repressor variant ablates mesodermal Delta-1 expression in vivo. Furthermore, MyoD-dependent Delta-1 induction is sufficient to activate transcription from promoters of E(spl)-related genes in a Notch-dependent manner. These results indicate that a hallmark of neural cell fate determination, i.e. the feedback loop between differentiation promoting basic helix-loop-helix proteins and the Notch regulatory circuitry, is conserved in myogenesis, supporting a direct involvement of Notch in muscle determination.
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Affiliation(s)
- T Wittenberger
- Friedrich Miescher Laboratory, MPG, Spemannstrasse 37-39, D-72076 Tübingen, Germany
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