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Asashima M, Satou-Kobayashi Y. Spemann-Mangold organizer and mesoderm induction. Cells Dev 2024; 178:203903. [PMID: 38295873 DOI: 10.1016/j.cdev.2024.203903] [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: 11/13/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/09/2024]
Abstract
The discovery of the Spemann-Mangold organizer strongly influenced subsequent research on embryonic induction, with research aiming to elucidate the molecular characteristics of organizer activity being currently underway. Herein, we review the history of research on embryonic induction, and describe how the mechanisms of induction phenomena and developmental processes have been investigated. Classical experiments investigating the differentiation capacity and inductive activity of various embryonic regions were conducted by many researchers, and important theories of region-specific induction and the concept for chain of induction were proposed. The transition from experimental embryology to developmental biology has enabled us to understand the mechanisms of embryonic induction at the molecular level. Consequently, many inducing substances and molecules such as transcriptional factors and peptide growth factors involved in the organizer formation were identified. One of peptide growth factors, activin, acts as a mesoderm- and endoderm-inducing substance. Activin induces several tissues and organs from the undifferentiated cell mass of amphibian embryos in a concentration-dependent manner. We review the extent to which we can control in vitro organogenesis from undifferentiated cells, and discuss the application to stem cell-based regenerative medicine based on insights gained from animal experiments, such as in amphibians.
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Affiliation(s)
- Makoto Asashima
- Advanced Comprehensive Research Organization, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-0003, Japan.
| | - Yumeko Satou-Kobayashi
- Advanced Comprehensive Research Organization, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-0003, Japan
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Zhu K, Spaink HP, Durston AJ. Patterning of the Vertebrate Head in Time and Space by BMP Signaling. J Dev Biol 2023; 11:31. [PMID: 37489332 PMCID: PMC10366882 DOI: 10.3390/jdb11030031] [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: 01/10/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/26/2023] Open
Abstract
How head patterning is regulated in vertebrates is yet to be understood. In this study, we show that frog embryos injected with Noggin at different blastula and gastrula stages had their head development sequentially arrested at different positions. When timed BMP inhibition was applied to BMP-overexpressing embryos, the expression of five genes: xcg-1 (a marker of the cement gland, which is the front-most structure in the frog embryo), six3 (a forebrain marker), otx2 (a forebrain and mid-brain marker), gbx2 (an anterior hindbrain marker), and hoxd1 (a posterior hindbrain marker) were sequentially fixed. These results suggest that the vertebrate head is patterned from anterior to posterior in a progressive fashion and may involve timed actions of the BMP signaling.
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Affiliation(s)
- Kongju Zhu
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
- Department of Pathology, Brigham and Women's Hospital, 60 Fenwood Road, Boston, MA 02115, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Division of Genetics and Genomics, Boston Children's Hospital, Center for Life Sciences, Blackfan Circle, Boston, MA 02115, USA
| | - Herman P Spaink
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
| | - Antony J Durston
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
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Yoon J, Kumar V, Goutam RS, Kim SC, Park S, Lee U, Kim J. Bmp Signal Gradient Modulates Convergent Cell Movement via Xarhgef3.2 during Gastrulation of Xenopus Embryos. Cells 2021; 11:44. [PMID: 35011606 PMCID: PMC8750265 DOI: 10.3390/cells11010044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 01/31/2023] Open
Abstract
Gastrulation is a critical step in the establishment of a basic body plan during development. Convergence and extension (CE) cell movements organize germ layers during gastrulation. Noncanonical Wnt signaling has been known as major signaling that regulates CE cell movement by activating Rho and Rac. In addition, Bmp molecules are expressed in the ventral side of a developing embryo, and the ventral mesoderm region undergoes minimal CE cell movement while the dorsal mesoderm undergoes dynamic cell movements. This suggests that Bmp signal gradient may affect CE cell movement. To investigate whether Bmp signaling negatively regulates CE cell movements, we performed microarray-based screening and found that the transcription of Xenopus Arhgef3.2 (Rho guanine nucleotide exchange factor) was negatively regulated by Bmp signaling. We also showed that overexpression or knockdown of Xarhgef3.2 caused gastrulation defects. Interestingly, Xarhgef3.2 controlled gastrulation cell movements through interacting with Disheveled (Dsh2) and Dsh2-associated activator of morphogenesis 1 (Daam1). Our results suggest that Bmp gradient affects gastrulation cell movement (CE) via negative regulation of Xarhgef3.2 expression.
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Affiliation(s)
- Jaeho Yoon
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea; (J.Y.); (V.K.); (R.S.G.); (S.-C.K.)
- National Cancer Institute, Frederick, MD 21702, USA
| | - Vijay Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea; (J.Y.); (V.K.); (R.S.G.); (S.-C.K.)
| | - Ravi Shankar Goutam
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea; (J.Y.); (V.K.); (R.S.G.); (S.-C.K.)
| | - Sung-Chan Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea; (J.Y.); (V.K.); (R.S.G.); (S.-C.K.)
| | - Soochul Park
- Department of Biological Sciences, Sookmyung Women’s University, Seoul 04310, Korea;
| | - Unjoo Lee
- Department of Electrical Engineering, Hallym University, Chuncheon 24252, Korea;
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea; (J.Y.); (V.K.); (R.S.G.); (S.-C.K.)
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Wang C, Luo X, Qin H, Zhao C, Yang L, Yu T, Zhang Y, Huang X, Xu X, Qin Q, Liu S. Formation of autotriploid Carassius auratus and its fertility-related genes analysis. BMC Genomics 2021; 22:435. [PMID: 34107878 PMCID: PMC8191051 DOI: 10.1186/s12864-021-07753-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 05/25/2021] [Indexed: 11/17/2022] Open
Abstract
Background Formation of triploid organism is useful in genetics and breeding. In this study, autotriploid Carassius auratus (3nRR, 3n = 150) was generated from Carassius auratus red var. (RCC, 2n = 100) (♀) and autotetraploid Carassius auratus (4nRR, 4n = 200) (♂). The female 3nRR produced haploid, diploid and triploid eggs, whereas the male 3nRR was infertile. The aim of the present study was to explore fertility of potential candidate genes of 3nRR. Results Gonadal transcriptome profiling of four groups (3 females RCC (FRCC), 3 males 4nRR (M4nRR), 3 males 3nRR (M3nRR) and 3 females 3nRR (F3nRR)) was performed using RNA-SEq. A total of 78.90 Gb of clean short reads and 24,262 differentially expressed transcripts (DETs), including 20,155 in F3nRR vs. FRCC and 4,107 in M3nRR vs. M4nRR were identified. A total of 106 enriched pathways were identified through KEGG enrichment analysis. Out of the enriched pathways, 44 and 62 signalling pathways were identified in F3nRR vs. FRCC and M3nRR vs. M4nRR, respectively. A total of 80 and 25 potential candidate genes for fertility-related in F3nRR and M3nRR were identified, respectively, through GO, KEGG analyses and the published literature. Moreover, protein-protein interaction (PPI) network construction of these fertility-associated genes were performed. Analysis of the PPI networks showed that 6 hub genes (MYC, SOX2, BMP4, GATA4, PTEN and BMP2) were involved in female fertility of F3nRR, and 2 hub genes (TP53 and FGF2) were involved in male sterility of M3nRR. Conclusions Establishment of autotriploid fish offers an ideal model to study reproductive traits of triploid fish. RNA-Seq data revealed 6 genes, namely, MYC, SOX2, BMP4, GATA4, PTEN and BMP2, involved in the female fertility of the F3nRR. Moreover, 2 genes, namely, TP53 and FGF2, were related to the male sterility of the M3nRR. These findings provide information on reproduction and breeding in triploid fish. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07753-5.
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Affiliation(s)
- Chongqing Wang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Xiang Luo
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Huan Qin
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Chun Zhao
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Li Yang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Tingting Yu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Yuxin Zhang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Xu Huang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Xidan Xu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China
| | - Qinbo Qin
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China.
| | - Shaojun Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, College of Life Sciences, Hunan Normal University, Hunan, 410081, Changsha, People's Republic of China.
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Abstract
Cardiac development is a complex developmental process that is initiated soon after gastrulation, as two sets of precardiac mesodermal precursors are symmetrically located and subsequently fused at the embryonic midline forming the cardiac straight tube. Thereafter, the cardiac straight tube invariably bends to the right, configuring the first sign of morphological left–right asymmetry and soon thereafter the atrial and ventricular chambers are formed, expanded and progressively septated. As a consequence of all these morphogenetic processes, the fetal heart acquired a four-chambered structure having distinct inlet and outlet connections and a specialized conduction system capable of directing the electrical impulse within the fully formed heart. Over the last decades, our understanding of the morphogenetic, cellular, and molecular pathways involved in cardiac development has exponentially grown. Multiples aspects of the initial discoveries during heart formation has served as guiding tools to understand the etiology of cardiac congenital anomalies and adult cardiac pathology, as well as to enlighten novels approaches to heal the damaged heart. In this review we provide an overview of the complex cellular and molecular pathways driving heart morphogenesis and how those discoveries have provided new roads into the genetic, clinical and therapeutic management of the diseased hearts.
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Yang G, Qin Z, Kou H, Liang R, Zhao L, Jiang S, Lin L, Zhang K. A Comparative Genomic and Transcriptional Survey Providing Novel Insights into Bone Morphogenetic Protein 2 ( bmp2) in Fishes. Int J Mol Sci 2019; 20:E6137. [PMID: 31817477 PMCID: PMC6940749 DOI: 10.3390/ijms20246137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 11/29/2019] [Accepted: 12/03/2019] [Indexed: 12/13/2022] Open
Abstract
Intermuscular bones (IBs) are only found in the muscles of fish. Bone morphogenetic protein 2 (bmp2) is considered to be the most active single osteogenesis factor. It promotes cell proliferation and differentiation during bone repair, as well as inducing the formation of bones and cartilages in vivo. However, detailed investigations of this family in fish are incredibly limited. Here, we have used a variety of published and unpublished bmp2 sequences for teleosts and cartilage fish in order to explore and expand our understanding of bmp2 genes in fish. Our results confirmed that teleost genomes contain two or more bmp2 genes, and the diversity of bmp2 genes in vertebrates appears to be as a result of a combination of whole genome duplication (WGD) and gene loss. Differences were also observed in tissue distribution and relative transcription abundance of the bmp2s through a transcriptomic analysis. Our data also indicated that bmp2b may play an important role in the formation of IBs in teleosts. In addition, protein sequence alignments and 3D structural predictions of bmp2a and bmp2b supported their similar roles in fishes. To summarize, our existing work provided novel insights into the bmp2 family genes in fishes through a mixture of comparative genomic and transcriptomic analysis.
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Affiliation(s)
- Guang Yang
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
- Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, China
| | - Zhendong Qin
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
| | - Hongyan Kou
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
| | - Rishen Liang
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
| | - Lijuan Zhao
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
| | - Shoujia Jiang
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China;
| | - Li Lin
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
| | - Kai Zhang
- Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology, Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; (G.Y.); (Z.Q.); (R.L.); (L.Z.)
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong 93117, China
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Asymmetric paralog evolution between the "cryptic" gene Bmp16 and its well-studied sister genes Bmp2 and Bmp4. Sci Rep 2019; 9:3136. [PMID: 30816280 PMCID: PMC6395752 DOI: 10.1038/s41598-019-40055-1] [Citation(s) in RCA: 220] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 02/07/2019] [Indexed: 12/05/2022] Open
Abstract
The vertebrate gene repertoire is characterized by “cryptic” genes whose identification has been hampered by their absence from the genomes of well-studied species. One example is the Bmp16 gene, a paralog of the developmental key genes Bmp2 and -4. We focus on the Bmp2/4/16 group of genes to study the evolutionary dynamics following gen(om)e duplications with special emphasis on the poorly studied Bmp16 gene. We reveal the presence of Bmp16 in chondrichthyans in addition to previously reported teleost fishes and reptiles. Using comprehensive, vertebrate-wide gene sampling, our phylogenetic analysis complemented with synteny analyses suggests that Bmp2, -4 and -16 are remnants of a gene quartet that originated during the two rounds of whole-genome duplication (2R-WGD) early in vertebrate evolution. We confirm that Bmp16 genes were lost independently in at least three lineages (mammals, archelosaurs and amphibians) and report that they have elevated rates of sequence evolution. This finding agrees with their more “flexible” deployment during development; while Bmp16 has limited embryonic expression domains in the cloudy catshark, it is broadly expressed in the green anole lizard. Our study illustrates the dynamics of gene family evolution by integrating insights from sequence diversification, gene repertoire changes, and shuffling of expression domains.
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Suzuki A, Yoshida H, van Heeringen SJ, Takebayashi-Suzuki K, Veenstra GJC, Taira M. Genomic organization and modulation of gene expression of the TGF-β and FGF pathways in the allotetraploid frog Xenopus laevis. Dev Biol 2017; 426:336-359. [DOI: 10.1016/j.ydbio.2016.09.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 06/10/2016] [Accepted: 09/19/2016] [Indexed: 12/13/2022]
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Schille C, Schambony A. Signaling pathways and tissue interactions in neural plate border formation. NEUROGENESIS 2017; 4:e1292783. [PMID: 28352644 DOI: 10.1080/23262133.2017.1292783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/02/2017] [Accepted: 02/02/2017] [Indexed: 02/04/2023]
Abstract
The neural crest is a transient cell population that gives rise to various cell types of multiple tissues and organs in the vertebrate embryo. Neural crest cells arise from the neural plate border, a region localized at the lateral borders of the prospective neural plate. Temporally and spatially coordinated interaction with the adjacent tissues, the non-neural ectoderm, the neural plate and the prospective dorsolateral mesoderm, is required for neural plate border specification. Signaling molecules, namely BMP, Wnt and FGF ligands and corresponding antagonists are derived from these tissues and interact to induce the expression of neural plate border specific genes. The present mini-review focuses on the current understanding of how the NPB territory is formed and accentuates the need for coordinated interaction of BMP and Wnt signaling pathways and precise tissue communication that are required for the definition of the prospective NC in the competent ectoderm.
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Affiliation(s)
- Carolin Schille
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg , Erlangen, Germany
| | - Alexandra Schambony
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg , Erlangen, Germany
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Schille C, Heller J, Schambony A. Differential requirement of bone morphogenetic protein receptors Ia (ALK3) and Ib (ALK6) in early embryonic patterning and neural crest development. BMC DEVELOPMENTAL BIOLOGY 2016; 16:1. [PMID: 26780949 PMCID: PMC4717534 DOI: 10.1186/s12861-016-0101-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 01/05/2016] [Indexed: 01/01/2023]
Abstract
Background Bone morphogenetic proteins regulate multiple processes in embryonic development, including early dorso-ventral patterning and neural crest development. BMPs activate heteromeric receptor complexes consisting of type I and type II receptor-serine/threonine kinases. BMP receptors Ia and Ib, also known as ALK3 and ALK6 respectively, are the most common type I receptors that likely mediate most BMP signaling events. Since early expression patterns and functions in Xenopus laevis development have not been described, we have addressed these questions in the present study. Results Here we have analyzed the temporal and spatial expression patterns of ALK3 and ALK6; we have also carried out loss-of-function studies to define the function of these receptors in early Xenopus development. We detected both redundant and non-redundant roles of ALK3 and ALK6 in dorso-ventral patterning. From late gastrula stages onwards, their expression patterns diverged, which correlated with a specific, non-redundant requirement of ALK6 in post-gastrula neural crest cells. ALK6 was essential for induction of neural crest cell fate and further development of the neural crest and its derivatives. Conclusions ALK3 and ALK6 both contribute to the gene regulatory network that regulates dorso-ventral patterning; they play partially overlapping and partially non-redundant roles in this process. ALK3 and ALK6 are independently required for the spatially restricted activation of BMP signaling and msx2 upregulation at the neural plate border, whereas in post-gastrula development ALK6 exerts a highly specific, conserved function in neural crest development. Electronic supplementary material The online version of this article (doi:10.1186/s12861-016-0101-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carolin Schille
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany.
| | - Jens Heller
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany.
| | - Alexandra Schambony
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany.
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Organizer-derived Bmp2 is required for the formation of a correct Bmp activity gradient during embryonic development. Nat Commun 2014; 5:3766. [PMID: 24777107 PMCID: PMC4071459 DOI: 10.1038/ncomms4766] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 03/31/2014] [Indexed: 01/21/2023] Open
Abstract
Bone morphogenetic proteins (Bmps) control dorsoventral patterning of vertebrate embryos through the establishment of a ventrodorsal gradient of the activated downstream cytoplasmic effectors Smad1/5/8. Some Bmp ligands are expressed in the ventral and lateral regions and in the organizer during gastrulation of the embryo, but it remains unclear how organizer-derived Bmps contribute to total Bmp ligand levels and to the establishment of the correct phospho-Smad1/5/8 gradient along the ventrodorsal axis. Here we demonstrate that interference with organizer-specific Bmp2b signalling in zebrafish embryos alters the phospho-Smad1/5/8 gradient throughout the ventrodorsal axis, elevates the levels of the Bmp antagonist Chordin and dorsalizes the embryos. Moreover, we show that organizer-derived Bmp2b represses chordin transcription in the organizer and contributes to the control of the Chordin gradient. Combining these experimental results with simulations of Bmp’s reaction-diffusion dynamics, our data indicate that organizer-produced Bmp2b is required for the establishment and maintenance of a Bmp activity gradient and for appropriate embryonic dorsoventral patterning during gastrulation. The morphogen, Bmp, regulates differentiation of cell fates along the ventral to dorsal axis during vertebrate embryonic development. Here, Xue et al. show that Bmp2b produced by the organizer during early gastrulation in zebrafish embryos has a role in the establishment of an appropriate Bmp morphogen activity gradient and the correct dorsoventral patterning of the embryos.
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Klymkowsky MW, Rossi CC, Artinger KB. Mechanisms driving neural crest induction and migration in the zebrafish and Xenopus laevis. Cell Adh Migr 2010; 4:595-608. [PMID: 20962584 PMCID: PMC3011258 DOI: 10.4161/cam.4.4.12962] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 07/09/2010] [Indexed: 01/09/2023] Open
Abstract
The neural crest is an evolutionary adaptation, with roots in the formation of mesoderm. Modification of neural crest behavior has been is critical for the evolutionary diversification of the vertebrates and defects in neural crest underlie a range of human birth defects. There has been a tremendous increase in our knowledge of the molecular, cellular, and inductive interactions that converge on defining the neural crest and determining its behavior. While there is a temptation to look for simple models to explain neural crest behavior, the reality is that the system is complex in its circuitry. In this review, our goal is to identify the broad features of neural crest origins (developmentally) and migration (cellularly) using data from the zebrafish (teleost) and Xenopus laevis (tetrapod amphibian) in order to illuminate where general mechanisms appear to be in play, and equally importantly, where disparities in experimental results suggest areas of profitable study.
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Affiliation(s)
- Michael W Klymkowsky
- Department of Molecular, Cellular and Developmental Biology; University of Colorado Boulder; Boulder, CO USA
| | - Christy Cortez Rossi
- Department of Craniofacial Biology; University of Colorado Denver; School of Dental Medicine; Aurora, CO USA
| | - Kristin Bruk Artinger
- Department of Craniofacial Biology; University of Colorado Denver; School of Dental Medicine; Aurora, CO USA
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Sun Y, Zhang QJ, Zhong J, Wang YQ. Characterization and expression of AmphiBMP3 /3b gene in amphioxus Branchiostoma japonicum. Dev Growth Differ 2010; 52:157-67. [PMID: 20067497 DOI: 10.1111/j.1440-169x.2009.01150.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Bone morphogenetic proteins (BMPs) are responsible for regulating embryo development and tissue homeostasis beyond osteogenesis. However, the precise biological roles of BMP3 and BMP3b remain obscure to a certain extent. In the present study, we cloned an orthologous gene (AmphiBMP3/3b) from amphioxus (Branchiostoma japonicum) and found its exon/intron organization is highly conserved. Further, in situ hybridization revealed that the gene was strongly expressed in the dorsal neural plate of the embryos. The gene also appeared in Hatschek's left diverticulum, neural tube, preoral ciliated pit and gill slit of larvae, and adult tissues including ovary, neural tube and notochordal sheath. Additionally, real-time quantitative polymerase chain reaction (RTqPCR) analysis revealed that the expression displayed two peaks at gastrula and juvenile stages. These results indicated that AmphiBMP3/3b, a sole orthologue of vertebrate BMP3 and BMP3b, might antagonize ventralizing BMP2 orthologous signaling in embryonic development, play a role in the evolutionary precursors of adenohypophysis, as well as act in female ovary physiology in adult.
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Affiliation(s)
- Yi Sun
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China
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Thomas JT, Canelos P, Luyten FP, Moos M. Xenopus SMOC-1 Inhibits bone morphogenetic protein signaling downstream of receptor binding and is essential for postgastrulation development in Xenopus. J Biol Chem 2009; 284:18994-9005. [PMID: 19414592 PMCID: PMC2707235 DOI: 10.1074/jbc.m807759200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 02/26/2009] [Indexed: 11/06/2022] Open
Abstract
The bone morphogenetic protein (BMP) family of signaling molecules and their antagonists are involved in patterning of the body axis and numerous aspects of organogenesis. Classical biochemical purification and protein sequencing of highly purified fractions containing potent bone forming activity from bovine cartilage identified several BMPs together with a number of other proteins. One such protein was SMOC-2 (secreted modular calcium-binding protein-2), classified as belonging to the BM-40 family of modular extracellular proteins. Data regarding the biological function of SMOC-2 and closely related SMOC-1 remain limited, and their expression or function during embryological development is unknown. We therefore isolated the Xenopus ortholog of human SMOC-1 (XSMOC-1) and explored its function in Xenopus embryos. In gain-of-function assays, XSMOC-1 acted similarly to a BMP antagonist. However, in contrast to known extracellular ligand-binding BMP antagonists, such as noggin, SMOC antagonizes BMP activity in the presence of a constitutively active BMP receptor, indicating a mechanism of action downstream of the receptor. We provide several lines of evidence to suggest that SMOC acts downstream of the BMP receptor via MAPK-mediated phosphorylation of the Smad linker region. Loss-of-function studies, using antisense morpholino oligonucleotides, revealed XSMOC-1 to be essential for postgastrulation development. The catastrophic developmental failure observed following XSMOC knockdown resembles that observed following simultaneous depletion of three ligand-binding BMP antagonists described in prior studies. These findings provide a direct link between the extracellular matrix-associated protein SMOC and a signaling pathway of general importance in anatomic patterning and cell or tissue fate specification.
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Affiliation(s)
- J. Terrig Thomas
- From the Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, United States Food and Drug Administration, Bethesda, Maryland 20892 and
| | - Paola Canelos
- From the Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, United States Food and Drug Administration, Bethesda, Maryland 20892 and
| | - Frank P. Luyten
- the Laboratory for Skeletal Development and Joint Disorders, Division of Rheumatology, Department of Musculoskeletal Sciences, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Malcolm Moos
- From the Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, United States Food and Drug Administration, Bethesda, Maryland 20892 and
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15
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Steinert S, Kroll TC, Taubert I, Pusch L, Hortschansky P, Höffken K, Wölfl S, Clement JH. Differential expression of cancer-related genes by single and permanent exposure to bone morphogenetic protein 2. J Cancer Res Clin Oncol 2008; 134:1237-45. [PMID: 18446370 DOI: 10.1007/s00432-008-0396-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 04/10/2008] [Indexed: 01/12/2023]
Abstract
PURPOSE Bone morphogenetic proteins (BMPs) are multifunctional regulators of various cell functions. The BMP-signalling network plays a pivotal role during embryogenesis and tumorigenesis. BMPs, e.g. BMP-2 exert their biological function in a time and concentration-dependent manner but also modulated by the context of the cellular microenvironment. In this study, we investigated the effect of a steady high level of BMP-2 versus a single application of BMP-2 on the breast cancer cell line MCF-7. METHODS The effect of the incubation regimes was analysed by DNA microarray expression profiling. Data were verified by real-time PCR. The protein expression of apoptosis-related genes was studied by western blot analysis. RESULTS We found a clear difference in the altered gene expression between the constant high level and the single application of BMP-2. After grouping the genes of interest into the biological processes of Gene Ontology, the group of apoptosis-related genes like BAX, BAG5 or PKR, was predominantly affected under the single-application regime of BMP-2. Among these protein kinase R was the most prominently regulated. Further studies on the protein level showed activation of PKR after 4 h with a subsequent enhanced phosphorylation of the PKR substrate eIF2alpha for several hours. CONCLUSIONS The duration of treatment and the concentration of BMP-2 affect the global expression pattern of MCF-7 cells. Among the regulated cancer-related genes, the cohort of the apoptosis-related genes showed the pronounced alterations. Our data point to a novel role of BMP-2 in the regulation of the PKR pathway in tumorigenesis.
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Affiliation(s)
- Susanne Steinert
- Clinic for Internal Medicine II, Friedrich-Schiller-University Jena, Erlanger Allee 101, 07740, Jena, Germany
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16
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Abstract
Bone morphogenetic proteins (BMPs) are known to be widely involved in various biological processes. Many of the members of the BMP family, as well as related factors, receptors and molecules in the BMP signaling pathway, have been isolated, but their precise functions are still unclear. In addition to the 'classical' model organism Xenopus, zebrafish, Danio rerio, is now considered to be a suitable model organism to study the roles of the BMP signaling pathway during embryogenesis. Mutagenesis screens have identified a number of mutants in the pathway. Although they do not cover the entire members of the BMP signaling cascade that are currently known, they serve as a powerful tool to broaden our understanding of BMP functions, in combination with other experimental techniques.
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Affiliation(s)
- Mariko Kondo
- Department of Biological Sciences, The University of Tokyo, Japan.
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17
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Abstract
How important is the contribution of mRNAs and proteins stored in the oocyte for determining the body plan of the Xenopus embryo? Here we review the current understanding of the roles of maternally supplied transcription factors, signaling molecules, and signaling regulators in establishing the ectoderm, mesoderm, and endoderm germ layers and the embryonic axes. Key essential asymmetries of VegT, Wnt11, and Ectodermin are described, as well as the complexity of maternal transcription factors that are involved in the initial expression of early zygotic genes.
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Affiliation(s)
- Janet Heasman
- Division of Developmental Biology ML7007, Cincinnati Children's Hospital Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA.
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18
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Little SC, Mullins MC. Extracellular modulation of BMP activity in patterning the dorsoventral axis. ACTA ACUST UNITED AC 2006; 78:224-42. [PMID: 17061292 DOI: 10.1002/bdrc.20079] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Signaling via bone morphogenetic proteins (BMPs) regulates a vast array of diverse biological processes in the developing embryo and in postembryonic life. Many insights into BMP signaling derive from studies of the BMP signaling gradients that pattern cell fates along the embryonic dorsal-ventral (DV) axis of both vertebrates and invertebrates. This review examines recent developments in the field of DV patterning by BMP signaling, focusing on extracellular modulation as a key mechanism in the formation of BMP signaling gradients in Drosophila, Xenopus, and zebrafish.
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Affiliation(s)
- Shawn C Little
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6058, USA
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19
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Kagiyama Y, Gotouda N, Sakagami K, Yasuda K, Mochii M, Araki M. Extraocular dorsal signal affects the developmental fate of the optic vesicle and patterns the optic neuroepithelium. Dev Growth Differ 2005; 47:523-36. [PMID: 16287484 DOI: 10.1111/j.1440-169x.2005.00828.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Dorsal-ventral (DV) specification in the early optic vesicle plays a crucial role in the proper development of the eye. To address the questions of how DV specification is determined and how it affects fate determination of the optic vesicle, isolated optic vesicles were cultured either in vitro or in ovo. The dorsal and ventral halves of the optic vesicle were fated to develop into retinal pigment epithelium (RPE) and neural retina, respectively, when they were separated from each other and cultured. In optic vesicles treated with collagenase to remove the surrounding tissues, the neuroepithelium gave rise to cRax expression but not Mitf, suggesting that surrounding tissues are necessary for RPE specification. This was also confirmed in in ovo explant cultures. Combination cultures of collagenase-treated optic vesicles with either the dorsal or ventral part of the head indicated that head-derived factors have an important role in the fate determination of the optic vesicle: in the optic vesicles co-cultured with the dorsal part of the head Mitf expression was induced in the neuroepithelium, while the ventral head portion did not have this effect. The dorsal head also suppressed Pax2 expression in the optic vesicle. These observations indicate that factors from the dorsal head portion have important roles in the establishment of DV polarity within the optic vesicle, which in turn induces the patterning and differentiation of the neural retina and pigment epithelium.
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Affiliation(s)
- Yuka Kagiyama
- Developmental Neurobiology Laboratory, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
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20
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Marom K, Levy V, Pillemer G, Fainsod A. Temporal analysis of the early BMP functions identifies distinct anti-organizer and mesoderm patterning phases. Dev Biol 2005; 282:442-54. [PMID: 15950609 DOI: 10.1016/j.ydbio.2005.03.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 01/30/2005] [Accepted: 03/15/2005] [Indexed: 10/25/2022]
Abstract
BMP signaling performs multiple important roles during early embryogenesis. Signaling through the BMP pathway is mediated by different BMP ligands expressed in partially overlapping temporal and spatial patterns. Assignment of different BMP-dependent activities to the individual ligands has relied on the patterns of expression of the various BMP genes. Temporal analysis of BMP signaling prior to and during gastrulation was performed using glucocorticoid-controlled Smad proteins. Overexpression of the BMP-specific Smad1 and Smad5 revealed that suppression of Spemann's organizer formation in Xenopus embryos can only take place by activating the BMP pathway prior to the onset of gastrulation. Blocking BMP signaling with the inhibitory Smad, Smad6, results in dorsalized embryos or secondary axis induction, only when activated up to early gastrula stages. BMP2 efficiently represses organizer-specific transcription from the midblastula transition onwards while BMP4 is unable to prevent the early activation of organizer-specific genes. Manipulation of the BMP pathway during mid/late gastrula affects mesodermal patterning with no external phenotypic effects. These observations suggest that the malformations resulting from inhibition or promotion of organizer formation, ventralized or dorsalized, respectively, are the result of a very early BMP function, through its antagonism of organizer formation. This function is apparently fulfilled by BMP2 and only at its latest phase by BMP4. Subsequently, BMP functions in the patterning of the mesoderm with no apparent phenotypic effects.
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Affiliation(s)
- Karen Marom
- Department of Cellular Biochemistry and Human Genetics, Faculty of Medicine, Hebrew University, POB 12272, Jerusalem 91120, Israel
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21
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Peiffer DA, Von Bubnoff A, Shin Y, Kitayama A, Mochii M, Ueno N, Cho KWY. A Xenopus DNA microarray approach to identify novel direct BMP target genes involved in early embryonic development. Dev Dyn 2005; 232:445-56. [PMID: 15614776 DOI: 10.1002/dvdy.20230] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Bone morphogenetic proteins (BMPs), a subgroup of the transforming growth factor-beta (TGF-beta) superfamily, were originally isolated from bone on the basis of their ability to induce ectopic bone development. Although BMPs are involved in a wide range of developmental and physiological functions, very few vertebrate target genes in this pathway have been identified. To identify target genes regulated by the BMP growth factor family in Xenopus, large-scale microarray analyses were conducted to discover genes directly activated by this factor in dissociated animal cap tissues treated with a combination of the protein synthesis inhibitor cycloheximide and BMP2. Consequent expression patterns and behaviors of the most highly induced genes were analyzed by in situ and reverse transcriptase-polymerase chain reaction analyses. Here, we describe two sets of the most highly induced direct BMP target genes identified using microarrays prepared from two different stages of early Xenopus development. A wide variety of genes are induced by BMP2, ranging from cell cycle controllers, enzymes, signal transduction cascade components, and components of the blood and vascular system. The finding reinforces the notion that BMP signals play important roles in a variety of biological processes.
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Affiliation(s)
- Daniel A Peiffer
- Department of Developmental and Cell Biology, University of California, Irvine, California, USA
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22
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Wilm TP, Solnica-Krezel L. Essential roles of a zebrafish prdm1/blimp1 homolog in embryo patterning and organogenesis. Development 2005; 132:393-404. [PMID: 15623803 DOI: 10.1242/dev.01572] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During vertebrate development the dorsal gastrula or Spemann-Mangold organizer orchestrates axis formation largely by limiting the ventralizing and posteriorizing activity of bone morphogenetic proteins (BMPs). In mouse and Xenopus laevis, genes encoding the zinc finger transcriptional repressor Prdm1/Blimp1 (PR domain containing 1, with ZNF domain; previously named B lymphocyte-induced maturation protein 1) were recently shown to be expressed in the visceral endoderm and anterior endomesoderm, respectively, and the prechordal plate of gastrula stage embryos. Later in development Prdm1/Blimp1 is expressed in many other tissues, including pharyngeal arches, limb buds, otic vesicles, photoreceptor cell layer, slow muscle and cloaca. Based on misexpression and dominant-negative studies, Prdm1/Blimp1 was proposed to promote anterior endomesoderm and head development in Xenopus laevis. Here we report the isolation and functional characterization of zebrafish prdm1 exhibiting a dynamic and evolutionarily conserved expression pattern. Misexpression of prdm1 inhibits the formation of dorsoanterior structures and reduces expression of chordin, which encodes a BMP antagonist. Conversely, interference with Prdm1 translation using antisense morpholino oligonucleotides, increases chordin expression, while reducing expression of Bmp genes, and consequently dorsalizing the embryo. At the end of the gastrula period, prdm1 morphant embryos have enlarged animal-vegetal and anteroposterior embryonic axes. This altered embryo morphology is associated with augmented extension movements of dorsal tissues and normal posterior migration of ventral tissues. Additionally, Prdm1 activity is essential for proper development of slow muscle, the photoreceptor cell layer, branchial arches and pectoral fins. Our studies reveal essential roles for prdm1 in limiting the function of the gastrula organizer and regulating cell fate specification and morphogenetic processes in precise correspondence with its intricate expression pattern.
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Affiliation(s)
- Thomas P Wilm
- Vanderbilt University, Department of Biological Sciences, VU Station B 351634, Nashville, TN 37235-1634, USA
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23
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Cao Y, Knöchel S, Donow C, Miethe J, Kaufmann E, Knöchel W. The POU factor Oct-25 regulates the Xvent-2B gene and counteracts terminal differentiation in Xenopus embryos. J Biol Chem 2004; 279:43735-43. [PMID: 15292233 DOI: 10.1074/jbc.m407544200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Xvent-2B promoter is regulated by a BMP-2/4-induced transcription complex comprising Smad signal transducers and specific transcription factors. Using a yeast one-hybrid screen we have found that Oct-25, a Xenopus POU domain protein related to mammalian Oct-3/4, binds as an additional factor to the Xvent-2B promoter. This interaction was further confirmed by both in vitro and in vivo analyses. The Oct-25 gene is mainly transcribed during blastula and gastrula stages in the newly forming ectodermal and mesodermal germ layers. Luciferase reporter gene assay demonstrated that Oct-25 stimulates transcription of the Xvent-2B gene. This stimulation depends on the Oct-25 binding site and the bone morphogenetic protein-responsive element. Furthermore, Oct-25 interacts in vitro with components of the Xvent-2B transcription complex, like Smad1/4 and Xvent-2. Overexpression of Oct-25 results in anterior/posterior truncations and lack of differentiation for neuroectoderm- and mesoderm-derived tissues including blood cells. This effect is consistent with an evolutionarily conserved role of class V POU factors in the maintenance of an undifferentiated cell state. In Xenopus, the molecular mechanism underlying this process might be coupled to the expression of Xvent proteins.
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Affiliation(s)
- Ying Cao
- Abteilung Biochemie, Universität Ulm, Albert-Einstein-Allee 11, D-89081, Germany
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24
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Garcia-Lopez R, Vieira C, Echevarria D, Martinez S. Fate map of the diencephalon and the zona limitans at the 10-somites stage in chick embryos. Dev Biol 2004; 268:514-30. [PMID: 15063186 DOI: 10.1016/j.ydbio.2003.12.038] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2003] [Revised: 12/15/2003] [Accepted: 12/31/2003] [Indexed: 11/20/2022]
Abstract
The diencephalon is a central area of the vertebrate developing brain, where the thalamic nuclear complex, the pretectum and the anterior tegmental structures are generated. It has been subdivided into prosomeres, which are transversal domains defined by morphological and molecular criteria. The zona limitans intrathalamica is a central boundary in the diencephalon that separates the posterior diencephalon (prosomeres 1 and 2), from the anterior diencephalon (prosomere 3). This intrathalamic limit appears early on in neural tube development, and the molecular pattern that it reveals suggests an important role in the diencephalic histogenesis. We hereby present a fate map of the presumptive territories in the diencephalon of a chick embryo at the 10-11 somite stages (HH9-10), by homotopic and isochronic quail-chick grafts. The anatomical interpretation of chimeric brains was aided by correlative whole-mount in situ hybridization with RNA probes for chicken genes expressed in specific diencephalic territories. The resulting fate map describes the distribution of the presumptive diencephalic prosomeres in the neural tube, and demonstrates their topologically conserved relationships throughout the neural development. Moreover, we show that the presumptive epithelium of ZLI can be localized at early developmental stages in the diencephalic alar plate at the anterior limit of the Wnt8b gene expression domain.
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Affiliation(s)
- Raquel Garcia-Lopez
- Instituto de Neurociencias, UMH-CSIC, Universidad Miguel Hernandez, Alicante, Spain
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25
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Peterkin T, Gibson A, Patient R. GATA-6 maintains BMP-4 and Nkx2 expression during cardiomyocyte precursor maturation. EMBO J 2003; 22:4260-73. [PMID: 12912923 PMCID: PMC175790 DOI: 10.1093/emboj/cdg400] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
GATA-6 is expressed in presumptive cardiac mesoderm before gastrulation, but its role in heart development has been unclear. Here we show that Xenopus and zebrafish embryos, injected with antisense morpholino oligonucleotides designed specifically to knock-down translation of GATA-6 protein, are severely compromised for heart development. Injected embryos express greatly reduced levels of contractile machinery genes and, at the same stage, of regulatory genes such as bone morphogenetic protein-4 (BMP-4) and the Nkx2 family. In contrast, initial BMP and Nkx2 expression is normal, suggesting a maintenance role for GATA-6. Endoderm is critical for heart formation in several vertebrates including Xenopus, and separate perturbation of GATA-6 expression in the deep anterior endoderm and in the overlying heart mesoderm shows that GATA-6 is required in both for cardiogenesis. The GATA-6 requirement in cardiac mesoderm was confirmed in zebrafish, an organism in which endoderm is thought not to be necessary for heart formation. We therefore conclude that proper maturation of cardiac mesoderm requires GATA-6, which functions to maintain BMP-4 and Nkx2 expression.
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Affiliation(s)
- Tessa Peterkin
- Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
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26
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Schlosser G. Hypobranchial placodes in Xenopus laevis give rise to hypobranchial ganglia, a novel type of cranial ganglia. Cell Tissue Res 2003; 312:21-9. [PMID: 12712315 DOI: 10.1007/s00441-003-0710-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2002] [Accepted: 02/07/2002] [Indexed: 11/30/2022]
Abstract
Recently, a novel type of neurogenic placode was described in anurans. These hypobranchial placodes were recognized as ectodermal thickenings situated ventral to the second and third pharyngeal pouch that give rise to neurons of unknown fate. Here, the development of hypobranchial placodes in Xenopus laevis is described in more detail using in situ hybridization and immunohistochemistry for various placodal ( Six1, Eya1) and neurogenic ( NGNR-1, NeuroD, Delta-1, Hu, acetylated tubulin) markers. Moreover, the fate of hypobranchial placodes was determined by analyzing tadpoles that had received orthotopic grafts of ventral branchial arch ectoderm at embryonic stages from donor embryos injected with the lineage tracer green fluorescent protein. The neurogenic epibranchial and hypobranchial placodes are shown to develop in certain subregions of a broader branchial placodal area as defined by Six1 and Eya1 expression, viz., adjacent to the dorsal and ventral tip of the pharyngeal pouches, respectively. Grafting experiments show that each of the two hypobranchial placodes gives rise to a small and previously undescribed hypobranchial ganglion (identified by its immunoreactivity for the neuron-specific Hu protein) of unknown function located in the ventral branchial arch region. No contributions of hypobranchial placodes to any other ganglia (including cardiac ganglia and the ganglia of branchiomeric nerves located dorsal to pharyngeal pouches) were found.
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Affiliation(s)
- Gerhard Schlosser
- Brain Research Institute, University of Bremen, FB 2, PO Box 33 04 40, 28334, Bremen, Germany.
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27
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Knöchel S, Dillinger K, Köster M, Knöchel W. Structure and expression of Xenopus tropicalis BMP-2 and BMP-4 genes. Mech Dev 2001; 109:79-82. [PMID: 11677055 DOI: 10.1016/s0925-4773(01)00506-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Xenopus tropicalis BMP-2 and BMP-4 genes have been cloned and sequenced. A comparison with the corresponding genes from X. laevis reveals that the BMP-4 genes are conserved at a higher extent than the BMP-2 genes. This is especially evident for the intron sequences, but is also reflected by the exon sequences. While the amino acids of X. tropicalis and X. laevis BMP-4 proteins diverge at about 4%, those of BMP-2 proteins diverge at about 7%. By reverse transcriptase polymerase chain reaction analyses and whole mount in situ hybridizations, we demonstrate the temporal and spatial expression patterns of X. tropicalis BMP-2 and BMP-4 genes. BMP-2 is found to be expressed maternally, and later in development, in migrating heart progenitor cells as well as in the final heart, within the pineal gland and the olfactory placodes. BMP-4 is zygotically activated within the ventral marginal zone and later found in the eye, the otic vesicle, the heart and within blood islands. Although the overall patterns are very similar to those found in X. laevis, there is some distinct difference which might result from the accelerated development in X. tropicalis.
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Affiliation(s)
- S Knöchel
- Abteilung Biochemie, Universität Ulm, Albert-Einstein-Allee 11, D-89081, Ulm, Germany
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28
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Tiedemann H, Asashima M, Grunz H, Knöchel W. Pluripotent cells (stem cells) and their determination and differentiation in early vertebrate embryogenesis. Dev Growth Differ 2001; 43:469-502. [PMID: 11576166 DOI: 10.1046/j.1440-169x.2001.00599.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mammalian embryonic stem cells can be obtained from the inner cell mass of blastocysts or from primordial germ cells. These stem cells are pluripotent and can develop into all three germ cell layers of the embryo. Somatic mammalian stem cells, derived from adult or fetal tissues, are more restricted in their developmental potency. Amphibian ectodermal and endodermal cells lose their pluripotency at the early gastrula stage. The dorsal mesoderm of the marginal zone is determined before the mid-blastula transition by factors located after cortical rotation in the marginal zone, without induction by the endoderm. Secreted maternal factors (BMP, FGF and activins), maternal receptors and maternal nuclear factors (beta-catenin, Smad and Fast proteins), which form multiprotein transcriptional complexes, act together to initiate pattern formation. Following mid-blastula transition in Xenopus laevis (Daudin) embryos, secreted nodal-related (Xnr) factors become important for endoderm and mesoderm differentiation to maintain and enhance mesoderm induction. Endoderm can be induced by high concentrations of activin (vegetalizing factor) or nodal-related factors, especially Xnr5 and Xnr6, which depend on Wnt/beta-catenin signaling and on VegT, a vegetal maternal transcription factor. Together, these and other factors regulate the equilibrium between endoderm and mesoderm development. Many genes are activated and/or repressed by more than one signaling pathway and by regulatory loops to refine the tuning of gene expression. The nodal related factors, BMP, activins and Vg1 belong to the TGF-beta superfamily. The homeogenetic neural induction by the neural plate probably reinforces neural induction and differentiation. Medical and ethical problems of future stem cell therapy are briefly discussed.
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Affiliation(s)
- H Tiedemann
- Institut für Molekularbiologie und Biochemie der Freien Universtität Berlin, Arnimallee 22, D-14195 Berlin, Germany.
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29
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Breckenridge RA, Mohun TJ, Amaya E. A role for BMP signalling in heart looping morphogenesis in Xenopus. Dev Biol 2001; 232:191-203. [PMID: 11254357 DOI: 10.1006/dbio.2001.0164] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The heart develops from a linear tubular precursor, which loops to the right and undergoes terminal differentiation to form the multichambered heart. Heart looping is the earliest manifestation of left-right asymmetry and determines the eventual heart situs. The signalling processes that impart laterality to the unlooped heart tube and thus allow the developing organ to interpret the left-right axis of the embryo are poorly understood. Recent experiments in zebrafish led to the suggestion that bone morphogenetic protein 4 (BMP4) may impart laterality to the developing heart tube. Here we show that in Xenopus, as in zebrafish, BMP4 is expressed predominantly on the left of the linear heart tube. Furthermore we demonstrate that ectopic expression of Xenopus nodal-related protein 1 (Xnr1) RNA affects BMP4 expression in the heart, linking asymmetric BMP4 expression to the left-right axis. We show that transgenic embryos overexpressing BMP4 bilaterally in the heart tube tend towards a randomisation of heart situs in an otherwise intact left-right axis. Additionally, inhibition of BMP signalling by expressing noggin or a truncated, dominant negative BMP receptor prevents heart looping but allows the initial events of chamber specification and anteroposterior morphogenesis to occur. Thus in Xenopus asymmetric BMP4 expression links heart development to the left-right axis, by being both controlled by Xnr1 expression and necessary for heart looping morphogenesis.
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Affiliation(s)
- R A Breckenridge
- Wellcome/CRC Institute, Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, United Kingdom
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30
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Yasui K, Saiga H, Wang Y, Zhang PJ, Semba I. Early expressed genes showing a dichotomous developing pattern in the lancelet embryo. Dev Growth Differ 2001; 43:185-94. [PMID: 11284968 DOI: 10.1046/j.1440-169x.2001.00566.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lancelets (amphioxus), although showing the most similar anatomical features to vertebrates, never develop a vertebrate-like head but rather several structures specific to this animal. The lancelet anatomical specificity seems to be traceable to early developmental stages, such as the vertebrate dorsal and anterior-posterior determinations. The BMP and Wnt proteins play important roles in establishing the early basis of the dorsal structures and the head in vertebrates. The early behavior of BMP and Wnt may be also related to the specific body structures of lancelets. The expression patterns of a dpp-related gene, Bbbmp2/4, and two wnt-related genes, Bbwnt7 and Bbwnt8, have been studied in comparison with those of brachyury and Hnf-3beta class genes. The temporal expression patterns of these genes are similar to those of vertebrates; Bbbmp2/4 and Bbwnt8 are first expressed in the invaginating primitive gut and the equatorial region, respectively, at the initial gastrula stage. However, spatial expression pattern of Bbbmp2/4 differs significantly from the vertebrate cognates. It is expressed in the mid-dorsal inner layer of gastrulae and widely in the anterior region, in which vertebrates block BMP signaling. The present study suggests that the lancelet embryo may have two distinct developmental domains from the gastrula stage, the domains of which coincide later with the lateral diverticular and the somitocoelomic regions. The embryonic origin of the anterior-specific structures in lancelets corresponds to the anterior domain where Bbbmp2/4 is continuously expressed.
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Affiliation(s)
- K Yasui
- Department of Oral Anatomy 1, Kagoshima University Dental School, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
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31
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Abstract
Cranial placodes are focal regions of thickened ectoderm in the head of vertebrate embryos that give rise to a wide variety of cell types, including elements of the paired sense organs and neurons in cranial sensory ganglia. They are essential for the formation of much of the cranial sensory nervous system. Although relatively neglected today, interest in placodes has recently been reawakened with the isolation of molecular markers for different stages in their development. This has enabled a more finely tuned approach to the understanding of placode induction and development and in some cases has resulted in the isolation of inducing molecules for particular placodes. Both morphological and molecular data support the existence of a preplacodal domain within the cranial neural plate border region. Nonetheless, multiple tissues and molecules (where known) are involved in placode induction, and each individual placode is induced at different times by a different combination of these tissues, consistent with their diverse fates. Spatiotemporal changes in competence are also important in placode induction. Here, we have tried to provide a comprehensive review that synthesises the highlights of a century of classical experimental research, together with more modern evidence for the tissues and molecules involved in the induction of each placode.
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Affiliation(s)
- C V Baker
- Division of Biology 139-74, California Institute of Technology, Pasadena, California, 91125, USA.
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32
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Ito Y, Kuhara S, Tashiro K. In synergy with noggin and follistatin, Xenopus nodal-related gene induces sonic hedgehog on notochord and floor plate. Biochem Biophys Res Commun 2001; 281:714-9. [PMID: 11237716 DOI: 10.1006/bbrc.2001.4386] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In early development of vertebrates, sonic hedgehog functions in dorsal-ventral patterning of dorsal tissue (nervous system and somites). In Xenopus, sonic hedgehog (Xshh) is first expressed in the Spemann organizer/notochord and floor plate. We report here the mechanism governing Xshh mRNA induction in these regions. In animal cap assays, the antagonizing BMPs signal was not sufficient to induce Xshh mRNA expression; however, it could induce Xshh mRNA expression in the presence of Xnr-1. In whole embryos, when secondary axes were induced by coexpressing noggin and Xnr-1 or follistatin and Xnr-1, Xshh mRNA expression was observed in the notochord and floor plate within the induced axes. It seems apparent that spatially restricted Xshh mRNA expression is determined as intersection of the two signals.
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Affiliation(s)
- Y Ito
- Laboratory of Molecular Gene Technics, Department of Genetic Resources Technology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka, 812-8581, Japan
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33
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Davidson AJ, Zon LI. Turning mesoderm into blood: the formation of hematopoietic stem cells during embryogenesis. Curr Top Dev Biol 2001; 50:45-60. [PMID: 10948449 DOI: 10.1016/s0070-2153(00)50003-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The formation of hematopoietic stem cells during development occurs by a multistep process that begins with the induction of ventral mesoderm. This mesoderm is patterned during gastrulation by a bone morphogenetic protein (BMP) signaling pathway that is mediated, at least in part, by members of the Mix and Vent families of homeobox transcription factors. Following gastrulation, a subset of ventral mesoderm is specified to become hematopoietic stem cells. Key determinants of hematopoietic fate include the product of the zebrafish cloche gene and the basic helix-loop-helix transcription factor SCL. Future studies in Xenopus and zebrafish should reveal other critical factors in this developmental pathway.
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Affiliation(s)
- A J Davidson
- Division of Hematology/Oncology, Harvard Medical School, Boston, Massachusetts, USA
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34
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Walters MJ, Wayman GA, Christian JL. Bone morphogenetic protein function is required for terminal differentiation of the heart but not for early expression of cardiac marker genes. Mech Dev 2001; 100:263-73. [PMID: 11165483 DOI: 10.1016/s0925-4773(00)00535-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
To examine potential roles for bone morphogenetic proteins (BMPs) in cardiogenesis, we used intracellular BMP inhibitors to disrupt this signaling cascade in Xenopus embryos. BMP-deficient embryos showed endodermal defects, a reduction in cardiac muscle-specific gene expression, a decrease in the number of cardiomyocytes and cardia bifida. Early expression of markers of endodermal and precardiac fate, however, was not perturbed. Heart defects were observed even when BMP signal transduction was blocked only in cells that contribute primarily to endodermal, and not cardiac fates, suggesting a non-cell autonomous function. Our results suggest that BMPs are not required for expression of early transcriptional regulators of cardiac fate but are essential for migration and/or fusion of the heart primordia and cardiomyocyte differentiation.
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Affiliation(s)
- M J Walters
- Department of Cell and Developmental Biology, Oregon Health Sciences University, School of Medicine, Portland 97201-3098, USA
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35
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Abstract
Heart induction in Xenopus occurs in paired regions of the dorsoanterior mesoderm in response to signals from the Spemann organizer and underlying dorsoanterior endoderm. These tissues together are sufficient to induce heart formation in noncardiogenic ventral marginal zone mesoderm. Similarly, in avians the underlying definitive endoderm induces cardiogenesis in precardiac mesoderm. Heart-inducing factors in amphibians are not known, and although certain BMPs and FGFs can mimic aspects of cardiogenesis in avians, neither can induce the full range of activities elicited by the inducing tissues. Here we report that the Wnt antagonists Dkk-1 and Crescent can induce heart formation in explants of ventral marginal zone mesoderm. Other Wnt antagonists, including the frizzled domain-containing proteins Frzb and Szl, lacked this activity. Unlike Wnt antagonism, inhibition of BMP signaling did not promote cardiogenesis. Ectopic expression of GSK3beta, which inhibits beta-catenin-mediated Wnt signaling, also induced cardiogenesis in ventral mesoderm. Analysis of Wnt proteins expressed during gastrulation revealed that Wnt3A and Wnt8, but not Wnt5A or Wnt11, inhibited endogenous heart induction. These results indicate that diffusion of Dkk-1 and Crescent from the organizer initiate cardiogenesis in adjacent mesoderm by establishing a zone of low Wnt3A and Wnt8 activity.
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Affiliation(s)
- V A Schneider
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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36
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Gonzalez EM, Fekany-Lee K, Carmany-Rampey A, Erter C, Topczewski J, Wright CV, Solnica-Krezel L. Head and trunk in zebrafish arise via coinhibition of BMP signaling by bozozok and chordino. Genes Dev 2000; 14:3087-92. [PMID: 11124801 PMCID: PMC317122 DOI: 10.1101/gad.852400] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2000] [Accepted: 10/31/2000] [Indexed: 11/25/2022]
Abstract
Spatial variations in the levels of bone morphogenetic protein (BMP) signaling are a critical determinant of dorsoanterior-ventroposterior pattern in vertebrate embryos. Whereas BMP overexpression abolishes both head and trunk development, known single and double loss-of-function mutations in BMP inhibitors have less dramatic effects. We report that combining mutations in the zebrafish genes bozozok and chordino causes a synergistic loss of head and trunk, whereas most cells express ventro-posterior markers and develop into a tail. Genetic inactivation of BMP signaling fully suppresses these defects. Thus, a remarkably simple genetic mechanism, involving a coinhibition of BMP function by the partially overlapping bozozok and chordino pathways is used to specify vertebrate head and trunk.
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Affiliation(s)
- E M Gonzalez
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, USA
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37
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Abstract
The number of identified growth factors continues to increase rapidly with many being implicated in the development of the nervous system, although for most of them the autocrine and paracrine pathways of cellular regulation still remain to be elucidated. The primary olfactory pathway, consisting of the olfactory epithelium and olfactory bulb, is presented here as a very useful model for the analysis of growth factor function. Review of the available literature suggests that a large proportion of neuroactive growth factors and their receptors are present in the olfactory epithelium or olfactory bulb. Furthermore, the primary olfactory pathway is one of the most plastic in the nervous system with neurogenesis continuing to contribute new sensory neurones in the olfactory epithelium and new interneurones in the olfactory bulb throughout adult life. The rich diversity of growth factors and their receptors in the olfactory system indicates that it will be useful in elucidating how these molecules regulate the formation of the nervous system. The olfactory epithelium in particular is proving useful as a model for the actions of growth factors in directing the neuronal lineage from stem cell to mature neurone.
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Affiliation(s)
- A Mackay-Sima
- Centre for Molecular Neurobiology, School of Biomolecular and Biomedical Science, Griffith University, Brisbane, Australia.
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38
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Goutel C, Kishimoto Y, Schulte-Merker S, Rosa F. The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish. Mech Dev 2000; 99:15-27. [PMID: 11091070 DOI: 10.1016/s0925-4773(00)00470-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.
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Affiliation(s)
- C Goutel
- INSERM U 368, Ecole Normale Supérieure, 46 rue d'Ulm, 75005, Paris, France
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39
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Schuler-Metz A, Knöchel S, Kaufmann E, Knöchel W. The homeodomain transcription factor Xvent-2 mediates autocatalytic regulation of BMP-4 expression in Xenopus embryos. J Biol Chem 2000; 275:34365-74. [PMID: 10938274 DOI: 10.1074/jbc.m003915200] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Like other genes of the transforming growth factor-beta family, the BMP-4 gene is regulated by an autocatalytic loop. In Xenopus embryos this loop can be ectopically induced by injection of BMP-2 RNA. However, cycloheximide treatment subsequent to BMP-2 overexpression revealed that BMP signaling is not direct but requires additional factor(s). As putative mediator we have identified Xvent-2 which is activated by BMP-2/4 signaling and, in turn, activates BMP-4 transcription. Using promoter/reporter assays we have delineated Xvent-2 responsive elements within the BMP-4 gene. We further demonstrate that Xvent-2 which has recently been characterized as a transcriptional repressor can also act, context dependent, as an activator binding two copies of a 5'-CTAATT-3' motif in the second intron of the BMP-4 gene. Replacement of Xvent-2 target sites within the goosecoid (gsc) promoter by the BMP-4 enhancer converts Xvent-2 caused repression of gsc to strong activation. This switch is obviously due to adjacent nucleotides probably binding a transcriptional co-activator interacting with Xvent-2. A model is presented describing the mechanism of BMP-4 gene activation in Xenopus embryos at the early gastrula stage.
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Affiliation(s)
- A Schuler-Metz
- Abteilung Biochemie, Universität Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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40
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Sparrow DB, Cai C, Kotecha S, Latinkic B, Cooper B, Towers N, Evans SM, Mohun TJ. Regulation of the tinman homologues in Xenopus embryos. Dev Biol 2000; 227:65-79. [PMID: 11076677 DOI: 10.1006/dbio.2000.9891] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vertebrate homologues of the Drosophila tinman transcription factor have been implicated in the processes of specification and differentiation of cardiac mesoderm. In Xenopus three members of this family have been isolated to date. Here we show that the XNkx2-3, Xnkx2-5, and XNkx2-10 genes are expressed in increasingly distinctive patterns in endodermal and mesodermal germ layers through early development, suggesting that their protein products (either individually or in different combinations) perform distinct functions. Using amphibian transgenesis, we find that the expression pattern of one of these genes, XNkx2-5, can be reproduced using transgenes containing only 4.3 kb of promoter sequence. Sequence analysis reveals remarkable conservation between the distalmost 300 bp of the Xenopus promoter and a portion of the AR2 element upstream of the mouse and human Nkx2-5 genes. Interestingly, only the 3' half of this evolutionarily conserved sequence element is required for correct transgene expression in frog embryos. Mutation of conserved GATA sites or a motif resembling the dpp-response element in the Drosophila tinman tinD enhancer dramatically reduces the levels of transgene expression. Finally we show that, despite its activity in Xenopus embryos, in transgenic mice the Xenopus Nkx2-5 promoter is able to drive reporter gene expression only in a limited subset of cells expressing the endogenous gene. This intriguing result suggests that despite evolutionary conservation of some cis-regulatory sequences, the regulatory controls on Nkx2-5 expression have diverged between mammals and amphibians.
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Affiliation(s)
- D B Sparrow
- Division of Developmental Biology, National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
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41
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Niehrs C, Dosch R, Onichtchouk D. Embryonic patterning of Xenopus mesoderm by Bmp-4. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2000:165-90. [PMID: 10943310 DOI: 10.1007/978-3-662-04264-9_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C Niehrs
- Division of Molecular Embryology, Deutsches Krebsforschungszentrum, Heidelberg, Germany
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42
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Faure S, Lee MA, Keller T, ten Dijke P, Whitman M. Endogenous patterns of TGFbeta superfamily signaling during early Xenopus development. Development 2000; 127:2917-31. [PMID: 10851136 DOI: 10.1242/dev.127.13.2917] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transforming growth factor beta (TGFbeta) superfamily signaling has been implicated in patterning of the early Xenopus embryo. Upon ligand stimulation, TGFbeta receptors phosphorylate Smad proteins at carboxy-terminal SS(V/M)S consensus motifs. Smads 1/5/8, activated by bone morphogenetic protein (BMP) signaling, induce ventral mesoderm whereas Smad2, activated by activin-like ligands, induces dorsal mesoderm. Although ectopic expression studies are consistent with roles for TGFbeta signals in early Xenopus embryogenesis, when and where BMP and activin-like signaling pathways are active endogenously has not been directly examined. In this study, we investigate the temporal and spatial activation of TGFbeta superfamily signaling in early Xenopus development by using antibodies specific for the type I receptor-phosphorylated forms of Smad1/5/8 and Smad2. We find that Smad1/5/8 and two distinct isoforms of Smad2, full-length Smad2 and Smad2(delta)exon3, are phosphorylated in early embryos. Both Smad1/5/8 and Smad2/Smad2(delta)exon3 are activated after, but not before, the mid-blastula transition (MBT). Endogenous activation of Smad2/Smad2(delta)exon3 requires zygotic transcription, while Smad1/5/8 activation at MBT appears to involve transcription-independent regulation. We also find that the competence of embryonic cells to respond to TGF(delta) superfamily ligands is temporally regulated and may be a determinant of early patterning. Levels of phospho-Smad1/5/8 and of phospho-Smad2/Smad2(delta)exon3 are asymmetrically distributed across both the animal-vegetal and dorsoventral axes. The timing of the development of these asymmetries differs for phospho-Smad1/5/8 and for phospho-Smad2/Smad2(delta)exon3, and the spatial distribution of phosphorylation of each Smad changes dramatically as gastrulation begins. We discuss the implications of our results for endogenous functions of BMP and activin-like signals as candidate morphogens regulating primary germ layer formation and dorsoventral patterning of the early Xenopus embryo.
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Affiliation(s)
- S Faure
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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43
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Angerer LM, Oleksyn DW, Logan CY, McClay DR, Dale L, Angerer RC. A BMP pathway regulates cell fate allocation along the sea urchin animal-vegetal embryonic axis. Development 2000; 127:1105-14. [PMID: 10662649 DOI: 10.1242/dev.127.5.1105] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To examine whether a BMP signaling pathway functions in specification of cell fates in sea urchin embryos, we have cloned sea urchin BMP2/4, analyzed its expression in time and space in developing embryos and assayed the developmental consequences of changing its concentration through mRNA injection experiments. These studies show that BMP4 mRNAs accumulate transiently during blastula stages, beginning around the 200-cell stage, 14 hours postfertilization. Soon after the hatching blastula stage, BMP2/4 transcripts can be detected in presumptive ectoderm, where they are enriched on the oral side. Injection of BMP2/4 mRNA at the one-cell stage causes a dose-dependent suppression of commitment of cells to vegetal fates and ectoderm differentiates almost exclusively as a squamous epithelial tissue. In contrast, NOGGIN, an antagonist of BMP2/4, enhances differentiation of endoderm, a vegetal tissue, and promotes differentiation of cells characteristic of the ciliated band, which contains neurogenic ectoderm. These findings support a model in which the balance of BMP2/4 signals produced by animal cell progeny and opposing vegetalizing signals sent during cleavage stages regulate the position of the ectoderm/ endoderm boundary. In addition, BMP2/4 levels influence the decision within ectoderm between epidermal and nonepidermal differentiation.
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Affiliation(s)
- L M Angerer
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
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44
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Eimon PM, Harland RM. In Xenopus embryos, BMP heterodimers are not required for mesoderm induction, but BMP activity is necessary for dorsal/ventral patterning. Dev Biol 1999; 216:29-40. [PMID: 10588861 DOI: 10.1006/dbio.1999.9496] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activity of bone morphogenetic protein (BMP) heterodimers has been shown to be more potent than that of homodimers in a number of contexts, including mesoderm induction. Although BMP-2/7 and -4/7 heterodimers are potent inducers of ventral mesoderm in ectodermal explants, we show that they are not a necessary component of the primary mesoderm-inducing signal in intact Xenopus embryos. The secreted BMP antagonists noggin and gremlin both efficiently block mesoderm induction by BMP homo- and heterodimers in animal caps. When these antagonists are ectopically expressed in the ventral marginal zone of early embryos the initial formation of mesoderm as indicated by panmesodermal markers remains unaffected. Only the subsequent dorsal/ventral patterning of this mesoderm appears to be altered, with expression of a number of organizer-specific transcripts observed in the marginal zone where BMP signaling has been abolished. Thus, we conclude that BMPs do not contribute an essential signal to mesodermal induction or patterning until gastrulation. The activities of noggin and gremlin are strikingly different from that of the multifunctional antagonist cerberus, which completely abolishes mesoderm induction when misexpressed during early development.
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Affiliation(s)
- P M Eimon
- Department of Molecular Biology, University of California, Berkeley, California, 94720-3202, USA
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45
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Grunz H. Gene expression and pattern formation during early embryonic development in amphibians. J Biosci 1999. [DOI: 10.1007/bf02942663] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46
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Kobayashi A, Sasakura Y, Ogasawara M, Makabe KW. A maternal RNA encoding smad1/5 is segregated to animal blastomeres during ascidian development. Dev Growth Differ 1999; 41:419-27. [PMID: 10466929 DOI: 10.1046/j.1440-169x.1999.00448.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Expressed Sequence Tag (EST) research on the ascidian Halocynthia roretzi revealed that Hrsmad1/5, a homolog of smad genes, is expressed in H. roretzi eggs. A comparison of amino acid sequences of smad family members showed that the isolated clone was a homolog of smad1 and smad5 of vertebrates. A molecular phylogenetic analysis showed that Hrsmad1/5 was separated from the common ancestor with the group containing smad1 and smad5. A northern blot analysis showed that transcript of Hrsmad1/5 was abundant in the fertilized egg. The amount of the transcript remained constant until the gastrulae and then rapidly decreased at the neurulae. The spatial expression of Hrsmad1/5 was investigated by means of whole-mount in situ hybridization. Maternal transcripts of Hrsmad1/5 were detected in the entire fertilized egg. The signals were localized preferentially to the animal blastomeres of the 8-, 16-, 32- and 64-cell stages. The zygotic expression of Hrsmad1/5 started in prospective epidermal blastomeres in the animal hemisphere at the 64-cell stage but not in cells of the central nervous system, and it decreased rapidly around the neural-plate stage. At the tail-bud stage, signals were detected broadly all through the trunk and in a small part of the epidermis in the tail region. This is the first report of a maternal RNA that preferentially accumulates in the animal hemisphere in early ascidian embryos. Animal blastomeres of ascidian embryos differentiate mainly into epidermis in a cell-autonomous manner and partly differentiate into neural tissues by induction. The Hrsmad1/5 gene may play a role in the signal transduction process in epidermal precursor cells of ascidian embryos.
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Affiliation(s)
- A Kobayashi
- Department of Zoology, Graduate School of Science, Kyoto University, Japan
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47
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Melby AE, Clements WK, Kimelman D. Regulation of dorsal gene expression in Xenopus by the ventralizing homeodomain gene Vox. Dev Biol 1999; 211:293-305. [PMID: 10395789 DOI: 10.1006/dbio.1999.9296] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Patterning in the vertebrate embryo is controlled by an interplay between signals from the dorsal organizer and the ventrally expressed BMPs. Here we examine the function of Vox, a homeodomain-containing gene that is activated by the ventralizing signal BMP-4. Inhibition of BMP signaling using a dominant negative BMP receptor (DeltaBMPR) leads to the ectopic activation of dorsal genes in the ventral marginal zone, and this activation is prevented by co-injection of Vox. chordin is the most strongly activated of those genes that are up-regulated by DeltaBMPR and is the gene most strongly inhibited by Vox expression. We demonstrate that Vox acts as a transcriptional repressor, showing that the activity of native Vox is mimicked by a Vox-repressor fusion (VoxEnR) and that a Vox-activator fusion (VoxG4A) acts as an antimorph, causing the formation of a partial secondary axis when expressed on the ventral side of the embryo. Although Vox can ectopically activate BMP-4 expression in whole embryos, we see no activation of BMP-4 by VoxG4A, demonstrating that this activation is indirect. Using a hormone-inducible version of VoxG4A, we find that a critical time window for Vox function is during the late blastula period. Using this construct, we demonstrate that only a subset of dorsal genes is directly repressed by Vox, revealing that there are different modes of regulation for organizer genes. Since the major direct target for Vox repression is chordin, we propose that Vox acts in establishing a BMP-4 morphogen gradient by restricting the expression domain of chordin.
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Affiliation(s)
- A E Melby
- Department of Biochemistry, University of Washington, Seattle, Washington, 98195-7350, USA
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48
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Abstract
The Xvent homeobox multigene family is essential for the patterning of the ventral mesoderm in Xenopus embryos. We have identified two novel members of this family, Xvent-1B and Xvent-2B, and have characterized their genomic structures. These two genes show a clustered organization and have probably arisen by gene duplication with subsequent inversion. Cis-regulatory elements within the promoters of both genes have been identified which contribute to their spatial activation. Xvent-2B is activated by BMP-2/4 in the absence of de novo protein synthesis, suggesting that this gene is a direct target of BMP-signalling. In contrast, Xvent-1B does not directly respond to BMP-2/4, but is activated by Xvent-2B. This activation is documented by Xvent-1B promoter/reporter studies, Xvent-2B overexpression and loss-of-function analysis using a dominant-negative Xvent-2 mutant. However, cycloheximide experiments reveal that Xvent-2B by itself is not sufficient to activate transcription of the Xvent-1B gene, but that there is a requirement for additional factor(s) being synthesized after midblastula transition.
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Affiliation(s)
- S Rastegar
- Abteilung Biochemie, Universität Ulm, Albert Einstein Allee 11, 89081, Ulm, Germany
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49
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Goto T, Kinoshita T. Maternal transcripts of mitotic checkpoint gene, Xbub3, are accumulated in the animal blastomeres of Xenopus early embryo. DNA Cell Biol 1999; 18:227-34. [PMID: 10098604 DOI: 10.1089/104454999315448] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Maternally transcribed mRNAs play the important role during early embryogenesis. Especially in patterning, distribution of the maternal transcripts has a causal relation to axis formation in the early embryo. We compared the quantity of mRNAs among four blastomeres of Xenopus 8-cell-stage embryos by the differential display method. A novel gene, Xbub3, was cloned by screening the oocyte cDNA library with an animal blastomere-enriched PCR product. Xbub3 is a homolog of the human mitotic checkpoint gene hBub3. A transcript of Xbub3 was 2940 bp and encoded a predicted protein of 330 amino acids with six WD repeats. Expression of Xbub3 was observed from oocyte to tadpole. Whole-mount in situ hybridization showed that Xbub3 mRNAs were uniformly distributed in the early stages of oogenesis but gradually localized to the animal hemisphere, especially in the perinuclear cytoplasm of full-grown oocytes. In the cleavage-stage embryos, the maternal transcripts of Xbub3 were recruited into each blastomere, associating closely with chromosomes. Zygotic expression of Xbub3 was widely detected in gastrula ectoderm and was gradually restricted to the central nervous systems, eyes, and branchial arches by the tadpole stage. This evidence contributes to understanding of the regulatory mechanism of the cell cycle and cell differentiation in the early embryo.
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Affiliation(s)
- T Goto
- Developmental Biology, Faculty of Science, Kwansei Gakuin University, Nishinomiya, Japan
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Nachaliel N, Re'Em-Kalma Y, Eshed O, Elias S, Frank D. BMP regulates vegetal pole induction centres in early xenopus development. Genes Cells 1998; 3:649-58. [PMID: 9893022 DOI: 10.1046/j.1365-2443.1998.00218.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Bone morphogenetic protein (BMP) plays an important role in mesoderm patterning in Xenopus. The ectopic expression of BMP-4 protein hyperventralizes embryos, whereas embryos expressing a BMP-2/4 dominant-negative receptor (DNR) are hyperdorsalized. Mesoderm is initially induced in the marginal zone by cells in the underlying vegetal pole. While much is known about BMP's expression and role in patterning the marginal zone, little is known about its early role in regulating vegetal mesoderm induction centre formation. RESULTS The role of BMP in regulating formation of vegetal mesoderm inducing centres during early Xenopus development was examined. Ectopic BMP-4 expression in vegetal pole cells inhibited dorsal mesoderm induction but increased ventral mesoderm induction when recombined with animal cap ectoderm in Nieuwkoop explants. 32-cell embryos injected with BMP-4 RNA in the most vegetal blastomere tier were not hyperdorsalized by LiCl treatment. The ectopic expression of Smad or Mix.1 proteins in the vegetal pole also inhibited dorsal mesoderm induction in explants and embryos. Expression of the BMP 2/4 DNR in the vegetal pole increased dorsal mesoderm induction and inhibited ventral mesoderm induction in explants and embryos. CONCLUSIONS These results support a role for BMP signalling in regulating ventral vegetal and dorsal vegetal mesoderm induction centre formation during early Xenopus development.
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Affiliation(s)
- N Nachaliel
- Department of Biochemistry, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
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