1
|
Janssen R, Budd GE. New insights into mesoderm and endoderm development, and the nature of the onychophoran blastopore. Front Zool 2024; 21:2. [PMID: 38267986 PMCID: PMC10809584 DOI: 10.1186/s12983-024-00521-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/09/2024] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND Early during onychophoran development and prior to the formation of the germ band, a posterior tissue thickening forms the posterior pit. Anterior to this thickening forms a groove, the embryonic slit, that marks the anterior-posterior orientation of the developing embryo. This slit is by some authors considered the blastopore, and thus the origin of the endoderm, while others argue that the posterior pit represents the blastopore. This controversy is of evolutionary significance because if the slit represents the blastopore, then this would support the amphistomy hypothesis that suggests that a slit-like blastopore in the bilaterian ancestor evolved into protostomy and deuterostomy. RESULTS In this paper, we summarize our current knowledge about endoderm and mesoderm development in onychophorans and provide additional data on early endoderm- and mesoderm-determining marker genes such as Blimp, Mox, and the T-box genes. CONCLUSION We come to the conclusion that the endoderm of onychophorans forms prior to the development of the embryonic slit, and thus that the slit is not the primary origin of the endoderm. It is thus unlikely that the embryonic slit represents the blastopore. We suggest instead that the posterior pit indeed represents the lips of the blastopore, and that the embryonic slit (and surrounding tissue) represents a morphologically superficial archenteron-like structure. We conclude further that both endoderm and mesoderm development are under control of conserved gene regulatory networks, and that many of the features found in arthropods including the model Drosophila melanogaster are likely derived.
Collapse
Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden
| |
Collapse
|
2
|
Keum BR, Yeo I, Koo Y, Han W, Choi SC, Kim GH, Han JK. Transmembrane protein 150b attenuates BMP signaling in the Xenopus organizer. J Cell Physiol 2023; 238:1850-1866. [PMID: 37435758 DOI: 10.1002/jcp.31059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 05/03/2023] [Accepted: 05/06/2023] [Indexed: 07/13/2023]
Abstract
The vertebrate organizer is a specified embryonic tissue that regulates dorsoventral patterning and axis formation. Although numerous cellular signaling pathways have been identified as regulators of the organizer's dynamic functions, the process remains incompletely understood, and as-yet unknown pathways remain to be explored for sophisticated mechanistic understanding of the vertebrate organizer. To identify new potential key factors of the organizer, we performed complementary DNA (cDNA) microarray screening using organizer-mimicking Xenopus laevis tissue. This analysis yielded a list of prospective organizer genes, and we determined the role of six-transmembrane domain containing transmembrane protein 150b (Tmem150b) in organizer function. Tmem150b was expressed in the organizer region and induced by Activin/Nodal signaling. In X. laevis, Tmem150b knockdown resulted in head defects and a shortened body axis. Moreover, Tmem150b negatively regulated bone morphogenetic protein (BMP) signaling, likely via physical interaction with activin receptor-like kinase 2 (ALK2). These findings demonstrated that Tmem150b functions as a novel membrane regulatory factor of BMP signaling with antagonistic effects, contributing to the understanding of regulatory molecular mechanisms of organizer axis function. Investigation of additional candidate genes identified in the cDNA microarray analysis could further delineate the genetic networks of the organizer during vertebrate embryogenesis.
Collapse
Affiliation(s)
- Byeong-Rak Keum
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
- Research Center for drug development, CYPHARMA, Daejeon, Korea
| | - Inchul Yeo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Youngmu Koo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Wonhee Han
- Department of Neurology, F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Sun-Cheol Choi
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Gun-Hwa Kim
- Research Center for drug development, CYPHARMA, Daejeon, Korea
- Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Cheongju, Korea
| | - Jin-Kwan Han
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| |
Collapse
|
3
|
Hagadorn MA, Hunter FK, DeLory T, Johnson MM, Pitts-Singer TL, Kapheim KM. Maternal body condition and season influence RNA deposition in the oocytes of alfalfa leafcutting bees ( Megachile rotundata). Front Genet 2023; 13:1064332. [PMID: 36685934 PMCID: PMC9845908 DOI: 10.3389/fgene.2022.1064332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 11/28/2022] [Indexed: 01/06/2023] Open
Abstract
Maternal effects are an important source of phenotypic variance, whereby females influence offspring developmental trajectory beyond direct genetic contributions, often in response to changing environmental conditions. However, relatively little is known about the mechanisms by which maternal experience is translated into molecular signals that shape offspring development. One such signal may be maternal RNA transcripts (mRNAs and miRNAs) deposited into maturing oocytes. These regulate the earliest stages of development of all animals, but are understudied in most insects. Here we investigated the effects of female internal (body condition) and external (time of season) environmental conditions on maternal RNA in the maturing oocytes and 24-h-old eggs (24-h eggs) of alfalfa leafcutting bees. Using gene expression and WGCNA analysis, we found that females adjust the quantity of mRNAs related to protein phosphorylation, transcriptional regulation, and nuclease activity deposited into maturing oocytes in response to both poor body condition and shorter day lengths that accompany the late season. However, the magnitude of these changes was higher for time of season. Females also adjusted miRNA deposition in response to seasonal changes, but not body condition. We did not observe significant changes in maternal RNAs in response to either body condition or time of season in 24-h eggs, which were past the maternal-to-zygotic transition. Our results suggest that females adjust the RNA transcripts they provide for offspring to regulate development in response to both internal and external environmental cues. Variation in maternal RNAs may, therefore, be important for regulating offspring phenotype in response to environmental change.
Collapse
Affiliation(s)
- Mallory A. Hagadorn
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Frances K. Hunter
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Tim DeLory
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Makenna M. Johnson
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States,United States Department of Agriculture, Agricultural Research Service, Pollinating Insects Research Unit, Logan, UT, United States
| | - Theresa L. Pitts-Singer
- United States Department of Agriculture, Agricultural Research Service, Pollinating Insects Research Unit, Logan, UT, United States
| | - Karen M. Kapheim
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States,*Correspondence: Karen M. Kapheim ,
| |
Collapse
|
4
|
Chen H, Good MC. Nascent transcriptome reveals orchestration of zygotic genome activation in early embryogenesis. Curr Biol 2022; 32:4314-4324.e7. [PMID: 36007528 PMCID: PMC9560990 DOI: 10.1016/j.cub.2022.07.078] [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: 02/01/2022] [Revised: 04/25/2022] [Accepted: 07/29/2022] [Indexed: 12/14/2022]
Abstract
Early embryo development requires maternal-to-zygotic transition, during which transcriptionally silent nuclei begin widespread gene expression during zygotic genome activation (ZGA).1-3 ZGA is vital for early cell fating and germ-layer specification,3,4 and ZGA timing is regulated by multiple mechanisms.1-5 However, controversies remain about whether these mechanisms are interrelated and vary among species6-10 and whether the timing of germ-layer-specific gene activation is temporally ordered.11,12 In some embryonic models, widespread ZGA onset is spatiotemporally graded,13,14 yet it is unclear whether the transcriptome follows this pattern. A major challenge in addressing these questions is to accurately measure the timing of each gene activation. Here, we metabolically label and identify the nascent transcriptome using 5-ethynyl uridine (5-EU) in Xenopus blastula embryos. We find that EU-RNA-seq outperforms total RNA-seq in detecting the ZGA transcriptome, which is dominated by transcription from maternal-zygotic genes, enabling improved ZGA timing determination. We uncover discrete spatiotemporal patterns for individual gene activation, a majority following a spatial pattern of ZGA that is correlated with a cell size gradient.14 We further reveal that transcription necessitates a period of developmental progression and that ZGA can be precociously induced by cycloheximide, potentially through elongation of interphase. Finally, most ectodermal genes are activated earlier than endodermal genes, suggesting a temporal orchestration of germ-layer-specific genes, potentially linked to the spatially graded pattern of ZGA. Together, our study provides fundamental new insights into the composition and dynamics of the ZGA transcriptome, mechanisms regulating ZGA timing, and its role in the onset of early cell fating.
Collapse
Affiliation(s)
- Hui Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew C Good
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
5
|
Abstract
The endoderm is the innermost germ layer that forms the linings of the respiratory and gastrointestinal tracts, and their associated organs, during embryonic development. Xenopus embryology experiments have provided fundamental insights into how the endoderm develops in vertebrates, including the critical role of TGFβ-signaling in endoderm induction,elucidating the gene regulatory networks controlling germ layer development and the key molecular mechanisms regulating endoderm patterning and morphogenesis. With new genetic, genomic, and imaging approaches, Xenopus is now routinely used to model human disease, discover mechanisms underlying endoderm organogenesis, and inform differentiation protocols for pluripotent stem cell differentiation and regenerative medicine applications. In this chapter, we review historical and current discoveries of endoderm development in Xenopus, then provide examples of modeling human disease and congenital defects of endoderm-derived organs using Xenopus.
Collapse
Affiliation(s)
- Nicole A Edwards
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
| | - Aaron M Zorn
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
| |
Collapse
|
6
|
Paraiso KD, Blitz IL, Coley M, Cheung J, Sudou N, Taira M, Cho KWY. Endodermal Maternal Transcription Factors Establish Super-Enhancers during Zygotic Genome Activation. Cell Rep 2020; 27:2962-2977.e5. [PMID: 31167141 PMCID: PMC6610736 DOI: 10.1016/j.celrep.2019.05.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 03/30/2019] [Accepted: 05/01/2019] [Indexed: 01/06/2023] Open
Abstract
Elucidation of the sequence of events underlying the dynamic interaction
between transcription factors and chromatin states is essential. Maternal
transcription factors function at the top of the regulatory hierarchy to specify
the primary germ layers at the onset of zygotic genome activation (ZGA). We
focus on the formation of endoderm progenitor cells and examine the interactions
between maternal transcription factors and chromatin state changes underlying
the cell specification process. Endoderm-specific factors Otx1 and Vegt together
with Foxh1 orchestrate endoderm formation by coordinated binding to select
regulatory regions. These interactions occur before the deposition of enhancer
histone marks around the regulatory regions, and these TFs recruit RNA
polymerase II, regulate enhancer activity, and establish super-enhancers
associated with important endodermal genes. Therefore, maternal transcription
factors Otx1, Vegt, and Foxh1 combinatorially regulate the activity of
super-enhancers, which in turn activate key lineage-specifying genes during
ZGA. How do maternal transcription factors interact with chromatin regions to
coordinate the endodermal gene regulatory program? Paraiso et al. demonstrate
that combinatorial binding of maternal Otx1, Vegt, and Foxh1 to select enhancers
and super-enhancers in the genome controls endodermal cell fate specification
during zygotic gene activation.
Collapse
Affiliation(s)
- Kitt D Paraiso
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Ira L Blitz
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Masani Coley
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Jessica Cheung
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Norihiro Sudou
- Department of Anatomy, Tokyo Women's Medical University, Tokyo, Japan
| | - Masanori Taira
- Department of Biological Sciences, Chuo University, Tokyo, Japan
| | - Ken W Y Cho
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA.
| |
Collapse
|
7
|
Reich S, Kayastha P, Teegala S, Weinstein DC. Tbx2 mediates dorsal patterning and germ layer suppression through inhibition of BMP/GDF and Activin/Nodal signaling. BMC Mol Cell Biol 2020; 21:39. [PMID: 32466750 PMCID: PMC7257154 DOI: 10.1186/s12860-020-00282-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 05/11/2020] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Members of the T-box family of DNA-binding proteins play a prominent role in the differentiation of the three primary germ layers. VegT, Brachyury, and Eomesodermin function as transcriptional activators and, in addition to directly activating the transcription of endoderm- and mesoderm-specific genes, serve as regulators of growth factor signaling during induction of these germ layers. In contrast, the T-box gene, tbx2, is expressed in the embryonic ectoderm, where Tbx2 functions as a transcriptional repressor and inhibits mesendodermal differentiation by the TGFβ ligand Activin. Tbx2 misexpression also promotes dorsal ectodermal fate via inhibition of the BMP branch of the TGFβ signaling network. RESULTS Here, we report a physical association between Tbx2 and both Smad1 and Smad2, mediators of BMP and Activin/Nodal signaling, respectively. We perform structure/function analysis of Tbx2 to elucidate the roles of both Tbx2-Smad interaction and Tbx2 DNA-binding in germ layer suppression. CONCLUSION Our studies demonstrate that Tbx2 associates with intracellular mediators of the Activin/Nodal and BMP/GDF pathways. We identify a novel repressor domain within Tbx2, and have determined that Tbx2 DNA-binding activity is required for repression of TGFβ signaling. Finally, our data also point to overlapping yet distinct mechanisms for Tbx2-mediated repression of Activin/Nodal and BMP/GDF signaling.
Collapse
Affiliation(s)
- Shoshana Reich
- The Graduate Center, The City University of New York, New York, NY, 10016, USA
| | - Peter Kayastha
- Department of Biology, Queens College, The City University of New York, Queens, NY, 11367, USA
| | - Sushma Teegala
- Department of Biology, Queens College, The City University of New York, Queens, NY, 11367, USA
| | - Daniel C Weinstein
- The Graduate Center, The City University of New York, New York, NY, 10016, USA. .,Department of Biology, Queens College, The City University of New York, Queens, NY, 11367, USA.
| |
Collapse
|
8
|
Goto T, Ito Y, Michiue T. Roles of Xenopus chemokine ligand CXCLh (XCXCLh) in early embryogenesis. Dev Growth Differ 2018; 60:226-238. [PMID: 29700804 DOI: 10.1111/dgd.12432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 03/08/2018] [Accepted: 03/15/2018] [Indexed: 01/13/2023]
Abstract
Several chemokine molecules control cell movements during early morphogenesis. However, it is unclear whether chemokine molecules affect cell fate. Here, we identified and characterized the CXC-type chemokine ligand in Xenopus laevis, Xenopus CXCLh (XCXCLh), during early embryogenesis. XCXCLh is expressed in the dorsal vegetal region at the gastrula stage. Both overexpression and knockdown of XCXCLh in the dorsal region inhibited gastrulation. XCXCLh contributed to the attraction of mesendodermal cells and accelerated the reassembly of scratched culture cells. Also, XCXCLh contributed to early endodermal induction. Overexpression of VegTmRNA or high concentrations of calcium ions induced XCXCLh expression. XCXCLh may play roles in both cell movements and differentiation during early Xenopus embryogenesis.
Collapse
Affiliation(s)
- Toshiyasu Goto
- Department of Molecular Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yuzuru Ito
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Tatsuo Michiue
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| |
Collapse
|
9
|
Butler AM, Owens DA, Wang L, King ML. A novel role for sox7 in Xenopus early primordial germ cell development: mining the PGC transcriptome. Development 2018; 145:dev.155978. [PMID: 29158442 DOI: 10.1242/dev.155978] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/06/2017] [Indexed: 12/26/2022]
Abstract
Xenopus primordial germ cells (PGCs) are determined by the presence of maternally derived germ plasm. Germ plasm components both protect PGCs from somatic differentiation and begin a unique gene expression program. Segregation of the germline from the endodermal lineage occurs during gastrulation, and PGCs subsequently initiate zygotic transcription. However, the gene network(s) that operate to both preserve and promote germline differentiation are poorly understood. Here, we utilized RNA-sequencing analysis to comprehensively interrogate PGC and neighboring endoderm cell mRNAs after lineage segregation. We identified 1865 transcripts enriched in PGCs compared with endoderm cells. We next compared the PGC-enriched transcripts with previously identified maternal, vegetally enriched transcripts and found that ∼38% of maternal transcripts were enriched in PGCs, including sox7 PGC-directed sox7 knockdown and overexpression studies revealed an early requirement for sox7 in germ plasm localization, zygotic transcription and PGC number. We identified pou5f3.3 as the most highly expressed and enriched POU5F1 homolog in PGCs. We compared the Xenopus PGC transcriptome with human PGC transcripts and showed that 80% of genes are conserved, underscoring the potential usefulness of Xenopus for understanding human germline specification.
Collapse
Affiliation(s)
- Amanda M Butler
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| | - Dawn A Owens
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| | - Lingyu Wang
- Department of Biology, University of Miami, Coral Gables, FL 33124, USA
| | - Mary Lou King
- Department of Cell Biology, University of Miami Miller School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| |
Collapse
|
10
|
Wei S, Wang Q. Molecular regulation of Nodal signaling during mesendoderm formation. Acta Biochim Biophys Sin (Shanghai) 2018; 50:74-81. [PMID: 29206913 DOI: 10.1093/abbs/gmx128] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 11/09/2017] [Indexed: 01/17/2023] Open
Abstract
One of the most important events during vertebrate embryogenesis is the formation or specification of the three germ layers, endoderm, mesoderm, and ectoderm. After a series of rapid cleavages, embryos form the mesendoderm and ectoderm during late blastulation and early gastrulation. The mesendoderm then further differentiates into the mesoderm and endoderm. Nodal, a member of the transforming growth factor β (TGF-β) superfamily, plays a pivotal role in mesendoderm formation by regulating the expression of a number of critical transcription factors, including Mix-like, GATA, Sox, and Fox. Because the Nodal signal transduction pathway is well-characterized, increasing effort has been made to delineate the spatiotemporal modulation of Nodal signaling during embryonic development. In this review, we summarize the recent progress delineating molecular regulation of Nodal signal intensity and duration during mesendoderm formation.
Collapse
Affiliation(s)
- Shi Wei
- The State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| |
Collapse
|
11
|
Tadjuidje E, Kofron M, Mir A, Wylie C, Heasman J, Cha SW. Nodal signalling in Xenopus: the role of Xnr5 in left/right asymmetry and heart development. Open Biol 2017; 6:rsob.150187. [PMID: 27488374 PMCID: PMC5008007 DOI: 10.1098/rsob.150187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 07/01/2016] [Indexed: 01/05/2023] Open
Abstract
Nodal class TGF-β signalling molecules play essential roles in establishing the vertebrate body plan. In all vertebrates, nodal family members have specific waves of expression required for tissue specification and axis formation. In Xenopus laevis, six nodal genes are expressed before gastrulation, raising the question of whether they have specific roles or act redundantly with each other. Here, we examine the role of Xnr5. We find it acts at the late blastula stage as a mesoderm inducer and repressor of ectodermal gene expression, a role it shares with Vg1. However, unlike Vg1, Xnr5 depletion reduces the expression of the nodal family member xnr1 at the gastrula stage. It is also required for left/right laterality by controlling the expression of the laterality genes xnr1, antivin (lefty) and pitx2 at the tailbud stage. In Xnr5-depleted embryos, the heart field is established normally, but symmetrical reduction in Xnr5 levels causes a severely stunted midline heart, first evidenced by a reduction in cardiac troponin mRNA levels, while left-sided reduction leads to randomization of the left/right axis. This work identifies Xnr5 as the earliest step in the signalling pathway establishing normal heart laterality in Xenopus.
Collapse
Affiliation(s)
- Emmanuel Tadjuidje
- Department of Biological Sciences, Alabama State University, 1627 Hall Street, Montgomery, AL 36101, USA
| | - Matthew Kofron
- Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Adnan Mir
- Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Christopher Wylie
- Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Janet Heasman
- Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Sang-Wook Cha
- Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| |
Collapse
|
12
|
Charney RM, Forouzmand E, Cho JS, Cheung J, Paraiso KD, Yasuoka Y, Takahashi S, Taira M, Blitz IL, Xie X, Cho KWY. Foxh1 Occupies cis-Regulatory Modules Prior to Dynamic Transcription Factor Interactions Controlling the Mesendoderm Gene Program. Dev Cell 2017; 40:595-607.e4. [PMID: 28325473 PMCID: PMC5434453 DOI: 10.1016/j.devcel.2017.02.017] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 12/24/2016] [Accepted: 02/16/2017] [Indexed: 12/14/2022]
Abstract
The interplay between transcription factors and chromatin dictates gene regulatory network activity. Germ layer specification is tightly coupled with zygotic gene activation and, in most metazoans, is dependent upon maternal factors. We explore the dynamic genome-wide interactions of Foxh1, a maternal transcription factor that mediates Nodal/TGF-β signaling, with cis-regulatory modules (CRMs) during mesendodermal specification. Foxh1 marks CRMs during cleavage stages and recruits the co-repressor Tle/Groucho in the early blastula. We highlight a population of CRMs that are continuously occupied by Foxh1 and show that they are marked by H3K4me1, Ep300, and Fox/Sox/Smad motifs, suggesting interplay between these factors in gene regulation. We also propose a molecular "hand-off" between maternal Foxh1 and zygotic Foxa at these CRMs to maintain enhancer activation. Our findings suggest that Foxh1 functions at the top of a hierarchy of interactions by marking developmental genes for activation, beginning with the onset of zygotic gene expression.
Collapse
Affiliation(s)
- Rebekah M Charney
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Elmira Forouzmand
- Department of Computer Science, Donald Bren School of Information & Computer Sciences, University of California, Irvine, CA 92697, USA
| | - Jin Sun Cho
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Jessica Cheung
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Kitt D Paraiso
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Yuuri Yasuoka
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
| | - Shuji Takahashi
- Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526, Japan
| | - Masanori Taira
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ira L Blitz
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Xiaohui Xie
- Department of Computer Science, Donald Bren School of Information & Computer Sciences, University of California, Irvine, CA 92697, USA
| | - Ken W Y Cho
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA.
| |
Collapse
|
13
|
Charney RM, Paraiso KD, Blitz IL, Cho KWY. A gene regulatory program controlling early Xenopus mesendoderm formation: Network conservation and motifs. Semin Cell Dev Biol 2017; 66:12-24. [PMID: 28341363 DOI: 10.1016/j.semcdb.2017.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 03/12/2017] [Accepted: 03/20/2017] [Indexed: 02/08/2023]
Abstract
Germ layer formation is among the earliest differentiation events in metazoan embryos. In triploblasts, three germ layers are formed, among which the endoderm gives rise to the epithelial lining of the gut tube and associated organs including the liver, pancreas and lungs. In frogs (Xenopus), where early germ layer formation has been studied extensively, the process of endoderm specification involves the interplay of dozens of transcription factors. Here, we review the interactions between these factors, summarized in a transcriptional gene regulatory network (GRN). We highlight regulatory connections conserved between frog, fish, mouse, and human endodermal lineages. Especially prominent is the conserved role and regulatory targets of the Nodal signaling pathway and the T-box transcription factors, Vegt and Eomes. Additionally, we highlight network topologies and motifs, and speculate on their possible roles in development.
Collapse
Affiliation(s)
- Rebekah M Charney
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Kitt D Paraiso
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Ira L Blitz
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Ken W Y Cho
- Department of Developmental and Cell Biology, Ayala School of Biological Sciences, University of California, Irvine, CA 92697, USA.
| |
Collapse
|
14
|
Tseng WC, Munisha M, Gutierrez JB, Dougan ST. Establishment of the Vertebrate Germ Layers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:307-381. [PMID: 27975275 DOI: 10.1007/978-3-319-46095-6_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The process of germ layer formation is a universal feature of animal development. The germ layers separate the cells that produce the internal organs and tissues from those that produce the nervous system and outer tissues. Their discovery in the early nineteenth century transformed embryology from a purely descriptive field into a rigorous scientific discipline, in which hypotheses could be tested by observation and experimentation. By systematically addressing the questions of how the germ layers are formed and how they generate overall body plan, scientists have made fundamental contributions to the fields of evolution, cell signaling, morphogenesis, and stem cell biology. At each step, this work was advanced by the development of innovative methods of observing cell behavior in vivo and in culture. Here, we take an historical approach to describe our current understanding of vertebrate germ layer formation as it relates to the long-standing questions of developmental biology. By comparing how germ layers form in distantly related vertebrate species, we find that highly conserved molecular pathways can be adapted to perform the same function in dramatically different embryonic environments.
Collapse
Affiliation(s)
- Wei-Chia Tseng
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Mumingjiang Munisha
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Juan B Gutierrez
- Department of Mathematics, University of Georgia, Athens, GA, 30602, USA.,Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
| | - Scott T Dougan
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
| |
Collapse
|
15
|
Zhang M, Skirkanich J, Lampson MA, Klein PS. Cell Cycle Remodeling and Zygotic Gene Activation at the Midblastula Transition. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:441-487. [DOI: 10.1007/978-3-319-46095-6_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
16
|
Sebé-Pedrós A, Ruiz-Trillo I. Evolution and Classification of the T-Box Transcription Factor Family. Curr Top Dev Biol 2017; 122:1-26. [DOI: 10.1016/bs.ctdb.2016.06.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
17
|
Localization in Oogenesis of Maternal Regulators of Embryonic Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 953:173-207. [DOI: 10.1007/978-3-319-46095-6_5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
18
|
Lombard-Banek C, Moody SA, Nemes P. High-Sensitivity Mass Spectrometry for Probing Gene Translation in Single Embryonic Cells in the Early Frog ( Xenopus) Embryo. Front Cell Dev Biol 2016; 4:100. [PMID: 27761436 PMCID: PMC5050209 DOI: 10.3389/fcell.2016.00100] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/29/2016] [Indexed: 01/01/2023] Open
Abstract
Direct measurement of protein expression with single-cell resolution promises to deepen the understanding of the basic molecular processes during normal and impaired development. High-resolution mass spectrometry provides detailed coverage of the proteomic composition of large numbers of cells. Here we discuss recent mass spectrometry developments based on single-cell capillary electrophoresis that extend discovery proteomics to sufficient sensitivity to enable the measurement of proteins in single cells. The single-cell mass spectrometry system is used to detect a large number of proteins in single embryonic cells in the 16-cell embryo of the South African clawed frog (Xenopus laevis) that give rise to distinct tissue types. Single-cell measurements of protein expression provide complementary information on gene transcription during early development of the vertebrate embryo, raising a potential to understand how differential gene expression coordinates normal cell heterogeneity during development.
Collapse
Affiliation(s)
| | - Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University Washington, DC, USA
| | - Peter Nemes
- Department of Chemistry, The George Washington University Washington, DC, USA
| |
Collapse
|
19
|
Oda-Ishii I, Kubo A, Kari W, Suzuki N, Rothbächer U, Satou Y. A Maternal System Initiating the Zygotic Developmental Program through Combinatorial Repression in the Ascidian Embryo. PLoS Genet 2016; 12:e1006045. [PMID: 27152625 PMCID: PMC4859511 DOI: 10.1371/journal.pgen.1006045] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 04/20/2016] [Indexed: 01/28/2023] Open
Abstract
Maternal factors initiate the zygotic developmental program in animal embryos. In embryos of the chordate, Ciona intestinalis, three maternal factors—Gata.a, β-catenin, and Zic-r.a—are required to establish three domains of gene expression at the 16-cell stage; the animal hemisphere, vegetal hemisphere, and posterior vegetal domains. Here, we show how the maternal factors establish these domains. First, only β-catenin and its effector transcription factor, Tcf7, are required to establish the vegetal hemisphere domain. Second, genes specifically expressed in the posterior vegetal domain have additional repressive cis-elements that antagonize the activity of β-catenin/Tcf7. This antagonizing activity is suppressed by Zic-r.a, which is specifically localized in the posterior vegetal domain and binds to DNA indirectly through the interaction with Tcf7. Third, Gata.a directs specific gene expression in the animal hemisphere domain, because β-catenin/Tcf7 weakens the Gata.a-binding activity for target sites through a physical interaction in the vegetal cells. Thus, repressive regulation through protein-protein interactions among the maternal transcription factors is essential to establish the first distinct domains of gene expression in the chordate embryo. During animal development, transcription factors and signaling molecules transcriptionally regulate one another and constitute a gene regulatory network. This network is evoked by maternally provided factors. Many maternal factors are localized and thereby activate a set of genes in a specific region. In embryos of the chordate, Ciona intestinalis, three maternal factors with localized activities are known. The present study demonstrated that these localized maternal factors interact with one another through a fourth non-localized transcription factor, Tcf7, and negatively regulate one another. These repressive interactions are essential to establish the first distinct domains of gene expression and evoke the gene regulatory network properly. The findings indicate that not only activating target genes but also repressing activities of other transcription factors through protein-protein interactions are important to properly initiate the zygotic program. Intriguingly, in one repressive interaction, a transcription factor loses its binding activity for target sites through an interaction with another transcription factor. Thus, this study provides a description of the entire system in which maternal factors initiate the zygotic developmental program of the Ciona embryo.
Collapse
Affiliation(s)
- Izumi Oda-Ishii
- Department of Zoology, Graduate School of Science, Kyoto University, Kita-Shirakawa Oiwake-cho, Sakyo, Kyoto, Japan
| | - Atsushi Kubo
- Department of Zoology, Graduate School of Science, Kyoto University, Kita-Shirakawa Oiwake-cho, Sakyo, Kyoto, Japan
| | - Willi Kari
- Department of Evolution and Developmental Biology, Zoological Institute, University Innsbruck, Innsbruck, Austria
| | - Nobuhiro Suzuki
- Department of Zoology, Graduate School of Science, Kyoto University, Kita-Shirakawa Oiwake-cho, Sakyo, Kyoto, Japan
| | - Ute Rothbächer
- Department of Evolution and Developmental Biology, Zoological Institute, University Innsbruck, Innsbruck, Austria
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Kita-Shirakawa Oiwake-cho, Sakyo, Kyoto, Japan
- * E-mail:
| |
Collapse
|
20
|
Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs. Proc Natl Acad Sci U S A 2016; 113:5628-33. [PMID: 27140624 DOI: 10.1073/pnas.1605547113] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs Engystomops randi, Epipedobates machalilla, Gastrotheca riobambae, and Eleutherodactylus coqui, as in Xenopus laevis embryos. Protein VegT was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was VegT-negative. This finding stimulated a vegt mRNA analysis in X. laevis eggs and embryos. vegt mRNA was detected in the animal region of X. laevis eggs and early embryos, in agreement with the VegT localization observed in the analyzed frogs. Moreover, a dorso-animal relocalization of vegt mRNA occurred in the egg at fertilization. Thus, the comparative analysis indicated that vegt may participate in dorsal development besides its known roles in endoderm development, and germ-layer specification. Zygotic vegt (zvegt) mRNA was detected as a minor isoform besides the major maternal (mvegt) isoform of the X. laevis egg. In addition, α-amanitin-insensitive vegt transcripts were detected around vegetal nuclei of the blastula. Thus, accumulation of vegt mRNA around vegetal nuclei was caused by relocalization rather than new mRNA synthesis. The localization of vegt mRNA around vegetal nuclei may contribute to the identity of vegetal blastomeres. These and previously reportedly localization features of vegt mRNA and protein derive from the master role of vegt in the development of frogs. The comparative analysis indicated that the strategies for endoderm, and dorsal specification, involving vegt and mix1, have been evolutionary conserved in frogs.
Collapse
|
21
|
Gao L, Zhu X, Chen G, Ma X, Zhang Y, Khand AA, Shi H, Gu F, Lin H, Chen Y, Zhang H, He L, Tao Q. A novel role for Ascl1 in the regulation of mesendoderm formation via HDAC-dependent antagonism of VegT. Development 2015; 143:492-503. [PMID: 26700681 PMCID: PMC4760308 DOI: 10.1242/dev.126292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 12/16/2015] [Indexed: 01/02/2023]
Abstract
Maternally expressed proteins function in vertebrates to establish the major body axes of the embryo and to establish a pre-pattern that sets the stage for later-acting zygotic signals. This pre-patterning drives the propensity of Xenopus animal cap cells to adopt neural fates under various experimental conditions. Previous studies found that the maternally expressed transcription factor, encoded by the Xenopus achaete scute-like gene ascl1, is enriched at the animal pole. Asc1l is a bHLH protein involved in neural development, but its maternal function has not been studied. Here, we performed a series of gain- and loss-of-function experiments on maternal ascl1, and present three novel findings. First, Ascl1 is a repressor of mesendoderm induced by VegT, but not of Nodal-induced mesendoderm. Second, a previously uncharacterized N-terminal domain of Ascl1 interacts with HDAC1 to inhibit mesendoderm gene expression. This N-terminal domain is dispensable for its neurogenic function, indicating that Ascl1 acts by different mechanisms at different times. Ascl1-mediated repression of mesendoderm genes was dependent on HDAC activity and accompanied by histone deacetylation in the promoter regions of VegT targets. Finally, maternal Ascl1 is required for animal cap cells to retain their competence to adopt neural fates. These results establish maternal Asc1l as a key factor in establishing pre-patterning of the early embryo, acting in opposition to VegT and biasing the animal pole to adopt neural fates. The data presented here significantly extend our understanding of early embryonic pattern formation. Summary: The proneural factor ASCL1 recruits HDAC1 to repress VegT-induced, but not Nodal-induced, mesendoderm formation via a previously uncharacterized N-terminal domain.
Collapse
Affiliation(s)
- Li Gao
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Xuechen Zhu
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Geng Chen
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Xin Ma
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Zhang
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Aftab A Khand
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Huijuan Shi
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Fei Gu
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Hao Lin
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Yuemeng Chen
- Tianjin Normal University College of Life Science, Binshuixidao (extension line) 393, Xinqing District, Tianjin 300387, China
| | - Haiyan Zhang
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Lei He
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| | - Qinghua Tao
- MOE Key Laboratory of Protein Sciences, Tsinghua University School of Life Sciences, Beijing 100084, China
| |
Collapse
|
22
|
Taylor DH, Chu ETJ, Spektor R, Soloway PD. Long non-coding RNA regulation of reproduction and development. Mol Reprod Dev 2015; 82:932-56. [PMID: 26517592 PMCID: PMC4762656 DOI: 10.1002/mrd.22581] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/03/2015] [Indexed: 12/13/2022]
Abstract
Noncoding RNAs (ncRNAs) have long been known to play vital roles in eukaryotic gene regulation. Studies conducted over a decade ago revealed that maturation of spliced, polyadenylated coding mRNA occurs by reactions involving small nuclear RNAs and small nucleolar RNAs; mRNA translation depends on activities mediated by transfer RNAs and ribosomal RNAs, subject to negative regulation by micro RNAs; transcriptional competence of sex chromosomes and some imprinted genes is regulated in cis by ncRNAs that vary by species; and both small-interfering RNAs and piwi-interacting RNAs bound to Argonaute-family proteins regulate post-translational modifications on chromatin and local gene expression states. More recently, gene-regulating noncoding RNAs have been identified, such as long intergenic and long noncoding RNAs (collectively referred to as lncRNAs)--a class totaling more than 100,000 transcripts in humans, which include some of the previously mentioned RNAs that regulate dosage compensation and imprinted gene expression. Here, we provide an overview of lncRNA activities, and then review the role of lncRNAs in processes vital to reproduction, such as germ cell specification, sex determination and gonadogenesis, sex hormone responses, meiosis, gametogenesis, placentation, non-genetic inheritance, and pathologies affecting reproductive tissues. Results from many species are presented to illustrate the evolutionarily conserved processes lncRNAs are involved in.
Collapse
Affiliation(s)
- David H. Taylor
- Field of Genetics, Genomics and Development, Cornell University, Ithaca, New York
| | - Erin Tsi-Jia Chu
- Field of Comparative Biomedical Sciences, Cornell University, Ithaca, New York
| | - Roman Spektor
- Field of Genetics, Genomics and Development, Cornell University, Ithaca, New York
| | - Paul D. Soloway
- Field of Genetics, Genomics and Development, Cornell University, Ithaca, New York
- Field of Comparative Biomedical Sciences, Cornell University, Ithaca, New York
- Division of Nutritional Sciences, Cornell University, Ithaca, New York
| |
Collapse
|
23
|
Abstract
The liver is a central regulator of metabolism, and liver failure thus constitutes a major health burden. Understanding how this complex organ develops during embryogenesis will yield insights into how liver regeneration can be promoted and how functional liver replacement tissue can be engineered. Recent studies of animal models have identified key signaling pathways and complex tissue interactions that progressively generate liver progenitor cells, differentiated lineages and functional tissues. In addition, progress in understanding how these cells interact, and how transcriptional and signaling programs precisely coordinate liver development, has begun to elucidate the molecular mechanisms underlying this complexity. Here, we review the lineage relationships, signaling pathways and transcriptional programs that orchestrate hepatogenesis.
Collapse
Affiliation(s)
- Miriam Gordillo
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | - Todd Evans
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | - Valerie Gouon-Evans
- Department of Developmental and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| |
Collapse
|
24
|
Katz Imberman S, Kolpakova A, Keren A, Bengal E. Myocyte enhancer factor 2D regulates ectoderm specification and adhesion properties of animal cap cells in the early Xenopus embryo. FEBS J 2015; 282:2930-47. [PMID: 26038288 DOI: 10.1111/febs.13331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/21/2015] [Accepted: 05/29/2015] [Indexed: 11/28/2022]
Abstract
In Xenopus, animal cap (AC) cells give rise to ectoderm and its derivatives: epidermis and the central nervous system. Ectoderm has long been considered a default pathway of embryonic development, with cells that are not under the influence of vegetal Nodal signaling adopting an ectodermal program of gene expression. In the present study, we describe the involvement of the animally-localized maternal transcription factor myocyte enhancer factor (Mef) 2D in regulating the identity of AC cells. We find that Mef2D is required for the formation of both ectodermal lineages: neural and epidermis. Gain and loss of function experiments indicate that Mef2D regulates early gastrula expression of key ectodermal/epidermal genes in the animal region. Mef2D controls the activity of zygotic bone morphogenetic protein (BMP) signaling known to dictate the epidermal differentiation program. Exogenous expression of Mef2D in vegetal blastomeres was sufficient to induce ectopic expression of ectoderm/epidermal genes in the vegetal half of the embryo, when Nodal signaling was inhibited. Depletion of Mef2D caused a loss of AC cell adhesion that was rescued by the expression of E-cadherin or bone morphogenetic protein 4. In addition, expression of Mef2D in the prospective endoderm caused unusual aggregation of vegetal cells with animal cells in vitro and inappropriate segregation to other germ layers in vivo. Mef2D cooperates with another animally-expressed transcription factor, FoxI1e. Together, they regulate the expression of genes encoding signaling proteins and the transcription factors that control the regional identity of animal cells. Therefore, we describe a new role for the animally-localized Mef2D protein in early ectoderm specification, which is similar to that of the vegetally-localized VegT in endoderm and mesoderm formation.
Collapse
Affiliation(s)
- Sandra Katz Imberman
- Department of Biochemistry, Rappaport Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Alina Kolpakova
- Department of Biochemistry, Rappaport Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Aviad Keren
- Department of Biochemistry, Rappaport Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Eyal Bengal
- Department of Biochemistry, Rappaport Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| |
Collapse
|
25
|
Single-cell mass spectrometry reveals small molecules that affect cell fates in the 16-cell embryo. Proc Natl Acad Sci U S A 2015; 112:6545-50. [PMID: 25941375 DOI: 10.1073/pnas.1423682112] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Spatial and temporal changes in molecular expression are essential to embryonic development, and their characterization is critical to understand mechanisms by which cells acquire different phenotypes. Although technological advances have made it possible to quantify expression of large molecules during embryogenesis, little information is available on metabolites, the ultimate indicator of physiological activity of the cell. Here, we demonstrate that single-cell capillary electrophoresis-electrospray ionization mass spectrometry is able to test whether differential expression of the genome translates to the domain of metabolites between single embryonic cells. Dissection of three different cell types with distinct tissue fates from 16-cell embryos of the South African clawed frog (Xenopus laevis) and microextraction of their metabolomes enabled the identification of 40 metabolites that anchored interconnected central metabolic networks. Relative quantitation revealed that several metabolites were differentially active between the cell types in the wild-type, unperturbed embryos. Altering postfertilization cytoplasmic movements that perturb dorsal development confirmed that these three cells have characteristic small-molecular activity already at cleavage stages as a result of cell type and not differences in pigmentation, yolk content, cell size, or position in the embryo. Changing the metabolite concentration caused changes in cell movements at gastrulation that also altered the tissue fates of these cells, demonstrating that the metabolome affects cell phenotypes in the embryo.
Collapse
|
26
|
Cao Y. Germ layer formation during Xenopus embryogenesis: the balance between pluripotency and differentiation. SCIENCE CHINA-LIFE SCIENCES 2015; 58:336-42. [DOI: 10.1007/s11427-015-4799-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 12/30/2014] [Indexed: 12/31/2022]
|
27
|
Aronson BE, Stapleton KA, Krasinski SD. Role of GATA factors in development, differentiation, and homeostasis of the small intestinal epithelium. Am J Physiol Gastrointest Liver Physiol 2014; 306:G474-90. [PMID: 24436352 PMCID: PMC3949026 DOI: 10.1152/ajpgi.00119.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The small intestinal epithelium develops from embryonic endoderm into a highly specialized layer of cells perfectly suited for the digestion and absorption of nutrients. The development, differentiation, and regeneration of the small intestinal epithelium require complex gene regulatory networks involving multiple context-specific transcription factors. The evolutionarily conserved GATA family of transcription factors, well known for its role in hematopoiesis, is essential for the development of endoderm during embryogenesis and the renewal of the differentiated epithelium in the mature gut. We review the role of GATA factors in the evolution and development of endoderm and summarize our current understanding of the function of GATA factors in the mature small intestine. We offer perspective on the application of epigenetics approaches to define the mechanisms underlying context-specific GATA gene regulation during intestinal development.
Collapse
Affiliation(s)
- Boaz E. Aronson
- 1Division of Gastroenterology and Nutrition, Department of Medicine, Children's Hospital Boston, and Harvard Medical School, Boston, Massachusetts; ,2Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; and
| | - Kelly A. Stapleton
- 1Division of Gastroenterology and Nutrition, Department of Medicine, Children's Hospital Boston, and Harvard Medical School, Boston, Massachusetts;
| | - Stephen D. Krasinski
- 1Division of Gastroenterology and Nutrition, Department of Medicine, Children's Hospital Boston, and Harvard Medical School, Boston, Massachusetts; ,3Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, Massachusetts
| |
Collapse
|
28
|
Chatterjee S, Elinson RP. Commitment to nutritional endoderm in Eleutherodactylus coqui involves altered nodal signaling and global transcriptional repression. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2013; 322:27-44. [PMID: 24323742 DOI: 10.1002/jez.b.22543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/11/2013] [Accepted: 09/24/2013] [Indexed: 01/01/2023]
Abstract
The vegetal cells of a Xenopus laevis embryo commit to mesendoderm via the Nodal-signaling pathway. In the direct developing frog Eleutherodactylus coqui, mesendoderm is specified at the marginal zone of the early gastrula, and vegetal core cells transform into nutritional endoderm. Nutritional endoderm, a novel tissue, consists of transient, yolky cells that provide nutrition but remain undifferentiated. We report a dual regulation for the generation of nutritional endoderm. First, differential expressions of the Nodal-signal transducers Smad2 and Smad4 were observed during early gastrulation between the marginal zone and the vegetal core cells. Although EcSmad2 RNA as well as total and activated Smad2 protein were detected in the vegetal core, Smad4 protein was expressed less in vegetal core during early gastrulation. Only 12% and 50% of vegetal core cells were positive for nuclear Smad2 and Smad4 signals respectively compared to 100% of marginal zone cells. These results suggest a signaling disruption in the vegetal core. Second, vegetal core cells were transcriptionally repressed. At the blastula stage, both marginal zone and vegetal core cells were transcriptionally silent, but during early gastrulation, only marginal zone cells became transcriptionally active. This indicates the occurrence of a mid-blastula transition in the marginal zone by early gastrulation, but global transcriptional repression persisted in the vegetal core and its derivative, nutritional endoderm, throughout development. We have described a novel mechanism, which prevents differentiation of the vegetal core through differential Nodal-signaling and global transcriptional repression.
Collapse
Affiliation(s)
- Suman Chatterjee
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania
| | | |
Collapse
|
29
|
Karadge U, Elinson RP. Characterization of the nutritional endoderm in the direct developing frog Eleutherodactylus coqui. Dev Genes Evol 2013; 223:351-62. [DOI: 10.1007/s00427-013-0451-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/14/2013] [Indexed: 12/01/2022]
|
30
|
Abstract
Developmental transcription factors are key players in animal multicellularity, being members of the T-box family that are among the most important. Until recently, T-box transcription factors were thought to be exclusively present in metazoans. Here, we report the presence of T-box genes in several nonmetazoan lineages, including ichthyosporeans, filastereans, and fungi. Our data confirm that Brachyury is the most ancient member of the T-box family and establish that the T-box family diversified at the onset of Metazoa. Moreover, we demonstrate functional conservation of a homolog of Brachyury of the protist Capsaspora owczarzaki in Xenopus laevis. By comparing the molecular phenotype of C. owczarzaki Brachyury with that of homologs of early branching metazoans, we define a clear difference between unicellular holozoan and metazoan Brachyury homologs, suggesting that the specificity of Brachyury emerged at the origin of Metazoa. Experimental determination of the binding preferences of the C. owczarzaki Brachyury results in a similar motif to that of metazoan Brachyury and other T-box classes. This finding suggests that functional specificity between different T-box classes is likely achieved by interaction with alternative cofactors, as opposed to differences in binding specificity.
Collapse
|
31
|
Lai F, King ML. Repressive translational control in germ cells. Mol Reprod Dev 2013; 80:665-76. [DOI: 10.1002/mrd.22161] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 02/02/2013] [Indexed: 02/04/2023]
Affiliation(s)
- Fangfang Lai
- Department of Cell Biology; University of Miami Miller School of Medicine; Miami; Florida
| | - Mary Lou King
- Department of Cell Biology; University of Miami Miller School of Medicine; Miami; Florida
| |
Collapse
|
32
|
Zhao J, Lambert G, Meijer AH, Rosa FM. The transcription factor Vox represses endoderm development by interacting with Casanova and Pou2. Development 2013; 140:1090-9. [DOI: 10.1242/dev.082008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Endoderm and mesoderm are both formed upon activation of Nodal signaling but how endoderm differentiates from mesoderm is still poorly explored. The sox-related gene casanova (sox32) acts downstream of the Nodal signal, is essential for endoderm development and requires the co-factor Pou2 (Pou5f1, Oct3, Oct4) in this process. Conversely, BMP signals have been shown to inhibit endoderm development by an as yet unexplained mechanism. In a search for Casanova regulators in zebrafish, we identified two of its binding partners as the transcription factors Pou2 and Vox, a member of the Vent group of proteins also involved in the patterning of the gastrula. In overexpression studies we show that vox and/or Vent group genes inhibit the capacity of Casanova to induce endoderm, even in the presence of its co-factor Pou2, and that Vox acts as a repressor in this process. We further show that vox, but not other members of the Vent group, is essential for defining the proper endodermal domain size at gastrulation. In this process, vox acts downstream of BMPs. Cell fate analysis further shows that Vox plays a key role downstream of BMP signals in regulating the capacity of Nodal to induce endoderm versus mesoderm by modulating the activity of the Casanova/Pou2 regulatory system.
Collapse
Affiliation(s)
- Jue Zhao
- INSERM U1024, F-75005 Paris, France
- CNRS UMR 8197, F-75005 Paris, France
- IBENS, Institut de Biologie de l’Ecole Normale Supérieure, F-75230 Paris, France
- College of Life Sciences, Peking University, Beijing 100871, P. R. China
| | - Guillaume Lambert
- INSERM U1024, F-75005 Paris, France
- CNRS UMR 8197, F-75005 Paris, France
- IBENS, Institut de Biologie de l’Ecole Normale Supérieure, F-75230 Paris, France
| | | | - Frederic M. Rosa
- INSERM U1024, F-75005 Paris, France
- CNRS UMR 8197, F-75005 Paris, France
- IBENS, Institut de Biologie de l’Ecole Normale Supérieure, F-75230 Paris, France
| |
Collapse
|
33
|
Cao Q, Zhang X, Lu L, Yang L, Gao J, Gao Y, Ma H, Cao Y. Klf4 is required for germ-layer differentiation and body axis patterning during Xenopus embryogenesis. Development 2012; 139:3950-61. [PMID: 22992953 DOI: 10.1242/dev.082024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Klf4 is a transcription factor of the family of Kruppel-like factors and plays important roles in stem cell biology; however, its function during embryogenesis is unknown. Here, we report the characterization of a Klf4 homologue in Xenopus laevis during embryogenesis. Klf4 is transcribed both maternally and zygotically and the transcript is ubiquitous in embryos during germ-layer formation. Klf4 promotes endoderm differentiation in both Nodal/Activin-dependent and -independent manners. Moreover, Klf4 regulates anteroposterior body axis patterning via activation of a subset of genes in the Spemann organizer, such as Noggin, Dkk1 and Cerberus, which encode Nodal, Wnt and BMP antagonists. Loss of Klf4 function leads to the failure of germ-layer differentiation, the loss of responsiveness of early embryonic cells to inducing signals, e.g. Nodal/Activin, and the loss of transcription of genes involved in axis patterning. We conclude that Klf4 is required for germ-layer differentiation and body axis patterning by means of rendering early embryonic cells competent to differentiation signals.
Collapse
Affiliation(s)
- Qing Cao
- Model Animal Research Center of Nanjing University and MOE Key Laboratory of Model Animals for Disease Study, 12 Xuefu Road, Pukou High-Tech Zone, 210061 Nanjing, China
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Cha SW, McAdams M, Kormish J, Wylie C, Kofron M. Foxi2 is an animally localized maternal mRNA in Xenopus, and an activator of the zygotic ectoderm activator Foxi1e. PLoS One 2012; 7:e41782. [PMID: 22848601 PMCID: PMC3407068 DOI: 10.1371/journal.pone.0041782] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/25/2012] [Indexed: 01/27/2023] Open
Abstract
Foxi1e is a zygotic transcription factor that is essential for the expression of early ectodermal genes. It is expressed in a highly specific pattern, only in the deep cell layers of the animal hemisphere, and in a mosaic pattern in which expressing cells are interspersed with non-expressing cells. Previous work has shown that several signals in the blastula control this expression pattern, including nodals, the TGFβ family member Vg1, and Notch. However, these are all inhibitory, which raises the question of what activates Foxi1e. In this work, we show that a related Forkhead family protein, Foxi2, is a maternal activator of Foxi1e. Foxi2 mRNA is maternally encoded, and highly enriched in animal hemisphere cells of the blastula. ChIP assays show that it acts directly on upstream regulatory elements of Foxi1e. Its effect is specific, since animal cells depleted of Foxi2 are able to respond normally to mesoderm inducing signals from vegetal cells. Foxi2 thus acts as a link between the oocyte and the early pathway to ectoderm, in a similar fashion to the vegetally localized VegT acts to initiate endoderm and mesoderm formation.
Collapse
Affiliation(s)
- Sang-Wook Cha
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Meredith McAdams
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Jay Kormish
- University of Calgary, Calgary, Alberta, Canada
| | - Christopher Wylie
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Matthew Kofron
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| |
Collapse
|
35
|
Pereira LA, Wong MS, Mei Lim S, Stanley EG, Elefanty AG. The Mix family of homeobox genes—Key regulators of mesendoderm formation during vertebrate development. Dev Biol 2012; 367:163-77. [DOI: 10.1016/j.ydbio.2012.04.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 04/24/2012] [Accepted: 04/30/2012] [Indexed: 10/28/2022]
|
36
|
Lai F, Singh A, King ML. Xenopus Nanos1 is required to prevent endoderm gene expression and apoptosis in primordial germ cells. Development 2012; 139:1476-86. [PMID: 22399685 DOI: 10.1242/dev.079608] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nanos is expressed in multipotent cells, stem cells and primordial germ cells (PGCs) of organisms as diverse as jellyfish and humans. It functions together with Pumilio to translationally repress targeted mRNAs. Here we show by loss-of-function experiments that Xenopus Nanos1 is required to preserve PGC fate. Morpholino knockdown of maternal Nanos1 resulted in a striking decrease in PGCs and a loss of germ cells from the gonads. Lineage tracing and TUNEL staining reveal that Nanos1-deficient PGCs fail to migrate out of the endoderm. They appear to undergo apoptosis rather than convert to normal endoderm. Whereas normal PGCs do not become transcriptionally active until neurula, Nanos1-depleted PGCs prematurely exhibit a hyperphosphorylated RNA polymerase II C-terminal domain at the midblastula transition. Furthermore, they inappropriately express somatic genes characteristic of endoderm regulated by maternal VegT, including Xsox17α, Bix4, Mixer, GATA4 and Edd. We further demonstrate that Pumilio specifically binds VegT RNA in vitro and represses, along with Nanos1, VegT translation within PGCs. Repressed VegT RNA in wild-type PGCs is significantly less stable than VegT in Nanos1-depleted PGCs. Our data indicate that maternal VegT RNA is an authentic target of Nanos1/Pumilio translational repression. We propose that Nanos1 functions to translationally repress RNAs that normally specify endoderm and promote apoptosis, thus preserving the germline.
Collapse
Affiliation(s)
- Fangfang Lai
- Department of Cell Biology, University of Miami School of Medicine, 1011 NW 15th St, Miami, FL 33136, USA
| | | | | |
Collapse
|
37
|
Bilogan CK, Horb ME. Xenopus staufen2 is required for anterior endodermal organ formation. Genesis 2012; 50:251-9. [PMID: 22162130 DOI: 10.1002/dvg.22000] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 11/29/2011] [Accepted: 12/01/2011] [Indexed: 01/30/2023]
Abstract
Defining the regulatory molecular networks involved in patterning the developing anterior endoderm is essential to understand how the pancreas, liver, stomach, and duodenum are discretely specified from each other. In this study, we analyzed the expression and function of the double-stranded RNA-binding protein Staufen2 in Xenopus laevis endoderm. We found that staufen2 was broadly expressed within the developing endoderm beginning at gastrulation becoming localized to the anterior endoderm at later stages. Through morpholino-mediated knockdown, we demonstrate that Staufen2 function is required for proper formation of the stomach, liver, and pancreas. We define that its function is required during gastrulation for proper patterning of the dorsal-ventral axis and that it acts to regulate expression of BMP signaling components.
Collapse
Affiliation(s)
- Cassandra K Bilogan
- Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, USA
| | | |
Collapse
|
38
|
Bentaya S, Ghogomu SM, Vanhomwegen J, Van Campenhout C, Thelie A, Dhainaut M, Bellefroid EJ, Souopgui J. The RNA-binding protein XSeb4R regulates maternal Sox3 at the posttranscriptional level during maternal-zygotic transition in Xenopus. Dev Biol 2012; 363:362-72. [PMID: 22261149 DOI: 10.1016/j.ydbio.2011.12.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/14/2011] [Accepted: 12/23/2011] [Indexed: 01/17/2023]
Abstract
The maternal-zygotic transition (MZT) is an embryonic event that overlaps with and plays key roles in primary germ layer specification in vertebrates. During MZT, maternally supplied mRNAs are degraded while zygotic transcripts are synthesized to either reinforce the already specified cell fate or to trigger new cell identity. Here, we show that forced expression of the RNA-binding protein, XSeb4R, in animal pole blastomeres of Xenopus embryos, inappropriately stabilizes transcripts there, including maternal Sox3. This leads to the impaired ability of the ectodermal progenitors to respond to factors regulating brain patterning and their eventual loss by apoptosis. XSeb4R protein binds specifically to the 3'UTR of Sox3 mRNA. XSeb4R gain-of-function in ectodermal explants reveals increased stability of the maternal Sox3 transcripts, associated with a robust Sox3 protein production. Conversely, whereas XSeb4R depletion abolishes VegT expression, the amount of the maternal Sox3 mRNA is rather increased but without augmentation in the amount of Sox3 protein. Moreover, XSeb4R protein knockdown leads to the modification of the ectoderm-mesoderm boundary, marked by expanded/shifted expression of the mesodermal marker genes such as Xbra and Apod, followed by an expression inhibition of Epi. K., an ectodermal marker. Overall, our data suggest XSeb4R as a novel player in gene expression regulation, acting at the posttranscriptional level during ectoderm specification in Xenopus.
Collapse
Affiliation(s)
- Souhila Bentaya
- Laboratoire de Génétique du Développement, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), rue des Profs. Jeener et Brachet 12, B-6041 Gosselies, Belgium
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Zaghloul NA, Yan B, Moody SA. Step-wise specification of retinal stem cells during normal embryogenesis. Biol Cell 2012; 97:321-37. [PMID: 15836431 DOI: 10.1042/bc20040521] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The specification of embryonic cells to produce the retina begins at early embryonic stages as a multi-step process that gradually restricts fate potentials. First, a subset of embryonic cells becomes competent to form retina by their lack of expression of endo-mesoderm-specifying genes. From these cells, a more restricted subset is biased to form retina by virtue of their close proximity to sources of bone morphogenetic protein antagonists during neural induction. During gastrulation, the definitive RSCs (retinal stem cells) are specified as the eye field by interactions with underlying mesoderm and the expression of a network of retina-specifying genes. As the eye field is transformed into the optic vesicle and optic cup, a heterogeneous population of RPCs (retinal progenitor cells) forms to give rise to the different domains of the retina: the optic stalk, retinal pigmented epithelium and neural retina. Further diversity of RPCs appears to occur under the influences of cell-cell interactions, cytokines and combinations of regulatory genes, leading to the differentiation of a multitude of different retinal cell types. This review examines what is known about each sequential step in retinal specification during normal vertebrate development, and how that knowledge will be important to understand how RSCs might be manipulated for regenerative therapies to treat retinal diseases.
Collapse
Affiliation(s)
- Norann A Zaghloul
- Department of Anatomy and Cell Biology, The George Washington University, 2300 Eye Street, NW, Washington, DC 20037, USA
| | | | | |
Collapse
|
40
|
Skirkanich J, Luxardi G, Yang J, Kodjabachian L, Klein PS. An essential role for transcription before the MBT in Xenopus laevis. Dev Biol 2011; 357:478-91. [PMID: 21741375 PMCID: PMC3164747 DOI: 10.1016/j.ydbio.2011.06.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Revised: 05/10/2011] [Accepted: 06/07/2011] [Indexed: 12/12/2022]
Abstract
Most zygotic genes remain transcriptionally silent in Drosophila, Xenopus, and zebrafish embryos through multiple mitotic divisions until the midblastula transition (MBT). Several genes have been identified in each of these organisms that are transcribed before the MBT, but whether precocious expression of specific mRNAs is important for later development has not been examined in detail. Here, we identify a class of protein coding transcripts activated before the MBT by the maternal T-box factor VegT that are components of an established transcriptional regulatory network required for mesendoderm induction in Xenopus laevis, including the Nodal related ligands xnr5, xnr6, and derrière and the transcription factors bix4, and sox17α. Accumulation of phospho-Smad2, a hallmark of active Nodal signaling, at the onset of the MBT requires preMBT transcription and activity of xnr5 and xnr6. Furthermore, preMBT activation of the Nodal pathway is essential for mesendodermal gene expression and patterning of the embryo. Finally, xnr5 and xnr6 can also activate their own expression during cleavage stages, indicating that preMBT transcription contributes to a feed-forward system that allows robust activation of Nodal signaling at the MBT.
Collapse
Affiliation(s)
| | - Guillaume Luxardi
- Institut de Biologie du Développement de Marseille Luminy, CNRS-Université de la Méditerranée, Marseille, France
| | - Jing Yang
- Nationwide Children’s Hospital, Columbus, OH, USA
| | - Laurent Kodjabachian
- Institut de Biologie du Développement de Marseille Luminy, CNRS-Université de la Méditerranée, Marseille, France
| | - Peter S. Klein
- Cell and Molecular Biology Graduate Group
- Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
41
|
Takechi M, Takeuchi M, Ota KG, Nishimura O, Mochii M, Itomi K, Adachi N, Takahashi M, Fujimoto S, Tarui H, Okabe M, Aizawa S, Kuratani S. Overview of the transcriptome profiles identified in hagfish, shark, and bichir: current issues arising from some nonmodel vertebrate taxa. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2011; 316:526-46. [PMID: 21809437 DOI: 10.1002/jez.b.21427] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/28/2011] [Accepted: 06/14/2011] [Indexed: 02/02/2023]
Abstract
Because of their crucial phylogenetic positions, hagfishes, sharks, and bichirs are recognized as key taxa in our understanding of vertebrate evolution. The expression patterns of the regulatory genes involved in developmental patterning have been analyzed in the context of evolutionary developmental studies. However, in a survey of public sequence databases, we found that the large-scale sequence data for these taxa are still limited. To address this deficit, we used conventional Sanger DNA sequencing and a next-generation sequencing technology based on 454 GS FLX sequencing to obtain expressed sequence tags (ESTs) of the Japanese inshore hagfish (Eptatretus burgeri; 161,482 ESTs), cloudy catshark (Scyliorhinus torazame; 165,819 ESTs), and gray bichir (Polypterus senegalus; 34,336 ESTs). We deposited the ESTs in a newly constructed database, designated the "Vertebrate TimeCapsule." The ESTs include sequences from genes that can be effectively used in evolutionary developmental studies; for instance, several encode cartilaginous extracellular matrix proteins, which are central to an understanding of the ways in which evolutionary processes affected the skeletal elements, whereas others encode regulatory genes involved in craniofacial development and early embryogenesis. Here, we discuss how hagfishes, sharks, and bichirs contribute to our understanding of vertebrate evolution, we review the current status of the publicly available sequence data for these three taxa, and we introduce our EST projects and newly developed database.
Collapse
Affiliation(s)
- Masaki Takechi
- Laboratory for Evolutionary Morphology, Center for Developmental Biology, RIKEN, Kobe, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Teo AKK, Arnold SJ, Trotter MWB, Brown S, Ang LT, Chng Z, Robertson EJ, Dunn NR, Vallier L. Pluripotency factors regulate definitive endoderm specification through eomesodermin. Genes Dev 2011; 25:238-50. [PMID: 21245162 DOI: 10.1101/gad.607311] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Understanding the molecular mechanisms controlling early cell fate decisions in mammals is a major objective toward the development of robust methods for the differentiation of human pluripotent stem cells into clinically relevant cell types. Here, we used human embryonic stem cells and mouse epiblast stem cells to study specification of definitive endoderm in vitro. Using a combination of whole-genome expression and chromatin immunoprecipitation (ChIP) deep sequencing (ChIP-seq) analyses, we established an hierarchy of transcription factors regulating endoderm specification. Importantly, the pluripotency factors NANOG, OCT4, and SOX2 have an essential function in this network by actively directing differentiation. Indeed, these transcription factors control the expression of EOMESODERMIN (EOMES), which marks the onset of endoderm specification. In turn, EOMES interacts with SMAD2/3 to initiate the transcriptional network governing endoderm formation. Together, these results provide for the first time a comprehensive molecular model connecting the transition from pluripotency to endoderm specification during mammalian development.
Collapse
|
43
|
Kher G, Trehan S, Misra A. Antisense Oligonucleotides and RNA Interference. CHALLENGES IN DELIVERY OF THERAPEUTIC GENOMICS AND PROTEOMICS 2011. [PMCID: PMC7150054 DOI: 10.1016/b978-0-12-384964-9.00007-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
44
|
Lai F, Zhou Y, Luo X, Fox J, King ML. Nanos1 functions as a translational repressor in the Xenopus germline. Mech Dev 2010; 128:153-63. [PMID: 21195170 DOI: 10.1016/j.mod.2010.12.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 12/08/2010] [Accepted: 12/13/2010] [Indexed: 02/01/2023]
Abstract
Nanos family members have been shown to act as translational repressors in the Drosophila and Caenorhabditis elegans germline, but direct evidence is missing for a similar function in vertebrates. Using a tethered function assay, we show that Xenopus Nanos1 is a translational repressor and that association with the RNA is required for this repression. We identified a 14 amino acid region within the N-terminal domain of Nanos1 that is conserved in organisms as diverse as sponge and Human. The region is found in all vertebrates but notably lacking in Drosophila and C. elegans. Deletion and substitution analysis revealed that this conserved region was required for Nanos1 repressive activity. Consistent with this observation, deletion of this region was sufficient to prevent abnormal development that results from ectopic expression of Nanos1 in oocytes. Although Nanos1 can repress capped and polyadenylated RNAs, Nanos1 mediated repression did not require the targeted RNA to have a cap or to be polyadenylated. These results suggest that Nanos1 is capable of repressing translation by several different mechanisms. We found that Nanos1, like Drosophila Nanos, associates with cyclin B1 RNA in vivo indicating that some Nanos targets may be evolutionarily conserved. Nanos1 protein was detected and thus available to repress mRNAs while PGCs were in the endoderm, but was not observed in PGCs after this stage.
Collapse
Affiliation(s)
- Fangfang Lai
- Department of Cell Biology and Anatomy, University of Miami School of Medicine, 1011 NW 15th St., Miami, FL 33136, USA
| | | | | | | | | |
Collapse
|
45
|
When one is better than two: RNA with dual functions. Biochimie 2010; 93:633-44. [PMID: 21111023 DOI: 10.1016/j.biochi.2010.11.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 11/17/2010] [Indexed: 11/23/2022]
Abstract
The central dogma of biology, until not long ago, held that genetic information stored on DNA molecules was translated into the final protein products through RNA as intermediate molecules. Then, an additional level of complexity in the regulation of genome expression was added, implicating new classes of RNA molecules called non-coding RNA (ncRNA). These ncRNA are also often referred to as functional RNA in that, although they do not contain the capacity to encode proteins, do have a function as RNA molecules. They have been thus far considered as truly non-coding RNA since no ORF long enough to be considered, nor protein, have been associated with them. However, the recent identification and characterization of bifunctional RNA, i.e. RNA for which both coding capacity and activity as functional RNA have been reported, suggests that a definite categorization of some RNA molecules is far from being straightforward. Indeed, several RNA primarily classified as non-protein-coding RNA has been showed to hold coding capacities and associated peptides. Conversely, mRNA, usually regarded as strictly protein-coding, may act as functional RNA molecules. Here, we describe several examples of these bifunctional RNA that have been already characterized from bacteria to mammals. We also extend this concept to fortuitous acquisition of dual function in pathological conditions and to the recently highlighted duality between information carried by a gene and its pseudogenes counterparts.
Collapse
|
46
|
Kennedy MW, Cha SW, Tadjuidje E, Andrews PG, Heasman J, Kao KR. A co-dependent requirement of xBcl9 and Pygopus for embryonic body axis development in Xenopus. Dev Dyn 2010; 239:271-83. [PMID: 19877304 DOI: 10.1002/dvdy.22133] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Wnt/beta-catenin transcriptional activation complex requires the adapter protein Pygopus (Pygo), which links the basal transcription machinery to beta-catenin, by its association with legless (Lgs)/ B-cell lymphoma-9 (Bcl9). Pygo was shown to be required for development in vertebrates, but the role of Lgs/Bcl9 is unknown. We identified an amphibian orthologue of Lgs/Bcl9, XBcl9, which interacted biochemically with Xbeta-catenin and XPygo2. The body axis promoting ability of Xbeta-catenin was diminished when residues required for its interaction with XBcl9 were mutated. In blastula embryos, XBcl9 was transiently preferentially expressed in nuclei of dorsoanterior cells and ectopically expressed XBcl9 required XPygo2 to localize to nuclei. Furthermore, while neither XBcl9 nor XPygo2 alone affected development when ectopically expressed, both were required to induce supernumerary axis and dorsal gene activation. Like XPygo2, depletion of maternal XBcl9 alone caused dorsal defects. These results indicated an essential role of the Pygo-Bcl9 duet in vertebrate body axis formation.
Collapse
Affiliation(s)
- Mark W Kennedy
- The Terry Fox Cancer Research Labs, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | | | | | | | | | | |
Collapse
|
47
|
Vaccaro MC, Gigliotti S, Graziani F, Carotenuto R, De Angelis C, Tussellino M, Campanella C. A transient asymmetric distribution of XNOA 36 mRNA and the associated spectrin network bisects Xenopus laevis stage I oocytes along the future A/V axis. Eur J Cell Biol 2010; 89:525-36. [PMID: 20226562 DOI: 10.1016/j.ejcb.2009.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 12/09/2009] [Accepted: 12/09/2009] [Indexed: 01/10/2023] Open
Abstract
In Xenopus oogenesis, the mechanisms governing the localisation of molecules crucial for primary axis determination have been uncovered in recent years. In stage I oocytes, the mitochondrial cloud (MC) entraps RNAs implicated in germ line specification and other RNAs, such as Xwnt-11 and Xlsirts, that are later delivered to the vegetal pole. Microfilaments and microtubules gradually develop in the cytoplasm, sustaining organelles as well as the MC. At stage III, other mRNAs migrate to the vegetal hemisphere through a microtubule-dependent mechanism. We report here the isolation of a cDNA encoding XNOA 36, a highly conserved protein, whose function is to date not fully understood. The XNOA 36 transcript is abundantly accumulated in stage I oocytes where it decorates a filamentous network. At the end of stage I the transcript gradually segregates in a sector of the oocyte surrounding the MC and opposite the ovarian hylum. Here, XNOA 36 mRNA distributes in a gradient-like pattern extending from a peripheral network towards the interior of the oocyte. This distribution is similar to that of alpha-spectrin mRNA. Both mRNAs are segregated in one half of the 250 microm oocytes, with the MC located between the XNOA 36/alpha-spectrin mRNA-labelled and unlabelled regions. XNOA 36 mRNA localisation was uncoupled from that of alpha-spectrin mRNA by cytochalasin B or ice-nocodazole treatments, suggesting that the two transcripts rely on different mechanisms for their localisation. However, immunolocalisation experiments coupled with in situ hybridisation revealed that the XNOA 36 transcript co-localises with the protein spectrin. This observation, together with the finding that XNOA 36 mRNA co-precipitates with spectrin, indicates that these two molecules interact physically. In conclusion, our data suggest that XNOA 36 mRNA is localized and/or anchored in the oocyte through a cytoskeletal network containing spectrin. The putative implications of this finding are discussed.
Collapse
Affiliation(s)
- M C Vaccaro
- Department of Structural and Functional Biology, University of Naples Federico II, Italy
| | | | | | | | | | | | | |
Collapse
|
48
|
Venkatarama T, Lai F, Luo X, Zhou Y, Newman K, King ML. Repression of zygotic gene expression in the Xenopus germline. Development 2010; 137:651-60. [PMID: 20110330 DOI: 10.1242/dev.038554] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Primordial germ cells (PGCs) in Xenopus are specified through the inheritance of germ plasm. During gastrulation, PGCs remain totipotent while surrounding cells in the vegetal mass become committed to endoderm through the action of the vegetal localized maternal transcription factor VegT. We find that although PGCs contain maternal VegT RNA, they do not express its downstream targets at the mid-blastula transition (MBT). Transcriptional repression in PGCs correlates with the failure to phosphorylate serine 2 in the carboxy-terminal domain (CTD) of the large subunit of RNA polymerase II (RNAPII). As serine 5 is phosphorylated, these results are consistent with a block after the initiation step but before the elongation step of RNAPII-based transcription. Repression of PGC gene expression occurs despite an apparently permissive chromatin environment. Phosphorylation of CTD-serine 2 and expression of zygotic mRNAs in PGCs are first detected at neurula, some 10 hours after MBT, indicating that transcription is significantly delayed in the germ cell lineage. Significantly, Oct-91, a POU subclass V transcription factor related to mammalian Oct3/4, is among the earliest zygotic transcripts detected in PGCs and is a likely mediator of pluripotency. Our findings suggest that PGCs are unable to respond to maternally inherited endoderm determinants because RNAPII activity is transiently blocked while these determinants are present. Our results in a vertebrate system further support the concept that one strategy used repeatedly during evolution for preserving the germline is RNAPII repression.
Collapse
Affiliation(s)
- Thiagarajan Venkatarama
- Department of Cell Biology and Anatomy, University of Miami School of Medicine, Miami, FL 33136, USA
| | | | | | | | | | | |
Collapse
|
49
|
Abstract
The use of stem cells in regenerative medicine holds great promise for the cure of many diseases, including type 1 diabetes mellitus (T1DM). Any potential stem-cell-based cure for T1DM should address the need for beta-cell replacement, as well as control of the autoimmune response to cells which express insulin. The ex vivo generation of beta cells suitable for transplantation to reconstitute a functional beta-cell mass has used pluripotent cells from diverse sources, as well as organ-specific facultative progenitor cells from the liver and the pancreas. The most effective protocols to date have produced cells that express insulin and have molecular characteristics that closely resemble bona fide insulin-secreting cells; however, these cells are often unresponsive to glucose, a characteristic that should be addressed in future protocols. The use of mesenchymal stromal cells or umbilical cord blood to modulate the immune response is already in clinical trials; however, definitive results are still pending. This Review focuses on current strategies to obtain cells which express insulin from different progenitor sources and highlights the main pathways and genes involved, as well as the different approaches for the modulation of the immune response in patients with T1DM.
Collapse
Affiliation(s)
- Cristina Aguayo-Mazzucato
- Section of Islet Transplantation and Cell Biology, Joslin Diabetes Center, Harvard Medical School, 1 Joslin Place, Boston, MA 02215, USA
| | | |
Collapse
|
50
|
Abstract
The endoderm germ layer contributes to the respiratory and gastrointestinal tracts and to all of their associated organs. Over the past decade, studies in vertebrate model organisms, including frog, fish, chick, and mouse, have greatly enhanced our understanding of the molecular basis of endoderm organ development. We review this progress with a focus on early stages of endoderm organogenesis including endoderm formation, gut tube morphogenesis and patterning, and organ specification. Lastly, we discuss how developmental mechanisms that regulate endoderm organogenesis are used to direct differentiation of embryonic stem cells into specific adult cell types, which function to alleviate disease symptoms in animal models.
Collapse
Affiliation(s)
- Aaron M Zorn
- Division of Developmental Biology, Cincinnati Children's Research Foundation and Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45229, USA.
| | | |
Collapse
|