151
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Robert B, Lallemand Y. Anteroposterior patterning in the limb and digit specification: contribution of mouse genetics. Dev Dyn 2006; 235:2337-52. [PMID: 16894622 DOI: 10.1002/dvdy.20890] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The limb has been a privileged object of investigation and reflection for scientists over the past two centuries and continues to provide a heuristic framework to analyze vertebrate development. Recently, accumulation of new data has significantly changed our view on the mechanisms of limb patterning, in particular along the anterior-posterior axis. These data have led us to revisit the mode of action of the zone of polarizing activity. They shed light on the molecular and cellular mechanisms of patterning linked to the Shh-Gli3 signaling pathway and give insights into the mechanism of activation of these cardinal factors, as well as the consequences of their activity. These new data are in good part the result of systematic Application of tools used in contemporary mouse molecular genetics. These have extended the power of mouse genetics by introducing mutational strategies that allow fine-tuned modulation of gene expression, interchromosomal deletions and duplication. They have even made the mouse embryo amenable to cell lineage analysis that used to be the realm of chick embryos. In this review, we focus on the data acquired over the last five years from the analysis of mouse limb development and discuss new perspectives opened by these results.
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Affiliation(s)
- Benoît Robert
- Department of Developmental Biology, CNRS URA 2578, Pasteur Institute, Paris, France.
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152
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Abstract
The cues governing cardiac cell-fate decisions, cardiac differentiation, and three-dimensional morphogenesis are rapidly being elucidated. Several themes are emerging that are relevant for childhood and adult heart disease and the growing field of stem cell biology. This review will consider our current understanding of cardiac cell-fate determination and cardiogenesis--largely derived from developmental studies in model organisms and human genetic approaches--and examine future implications for diagnosis, prevention, and treatment of heart disease in the young and old.
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Affiliation(s)
- Deepak Srivastava
- Gladstone Institute of Cardiovascular Disease and Department of Pediatrics and Biochemistry, University of California, San Francisco, CA 94158, USA.
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153
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Abstract
The heart, an ancient organ and the first to form and function during embryogenesis, evolved by the addition of new structures and functions to a primitive pump. Heart development is controlled by an evolutionarily conserved network of transcription factors that connect signaling pathways with genes for muscle growth, patterning, and contractility. During evolution, this ancestral gene network was expanded through gene duplication and co-option of additional networks. Mutations in components of the cardiac gene network cause congenital heart disease, the most common human birth defect. The consequences of such mutations reveal the logic of organogenesis and the evolutionary origins of morphological complexity.
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Affiliation(s)
- Eric N Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
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154
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Thewissen JGM, Cohn MJ, Stevens LS, Bajpai S, Heyning J, Horton WE. Developmental basis for hind-limb loss in dolphins and origin of the cetacean bodyplan. Proc Natl Acad Sci U S A 2006; 103:8414-8. [PMID: 16717186 PMCID: PMC1482506 DOI: 10.1073/pnas.0602920103] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Among mammals, modern cetaceans (whales, dolphins, and porpoises) are unusual in the absence of hind limbs. However, cetacean embryos do initiate hind-limb bud development. In dolphins, the bud arrests and degenerates around the fifth gestational week. Initial limb outgrowth in amniotes is maintained by two signaling centers, the apical ectodermal ridge (AER) and the zone of polarizing activity (ZPA). Our data indicate that the cetacean hind-limb bud forms an AER and that this structure expresses Fgf8 initially, but that neither the AER nor Fgf8 expression is maintained. Moreover, Sonic hedgehog (Shh), which mediates the signaling activity of the ZPA, is absent from the dolphin hind-limb bud. We find that failure to establish a ZPA is associated with the absence of Hand2, an upstream regulator of Shh. Interpreting our results in the context of both the cetacean fossil record and the known functions of Shh suggests that reduction of Shh expression may have occurred approximately 41 million years ago and led to the loss of distal limb elements. The total loss of Shh expression may account for the further loss of hind-limb elements that occurred near the origin of the modern suborders of cetaceans approximately 34 million years ago. Integration of paleontological and developmental data suggests that hind-limb size was reduced by gradually operating microevolutionary changes. Long after locomotor function was totally lost, modulation of developmental control genes eliminated most of the hind-limb skeleton. Hence, macroevolutionary changes in gene expression did not drive the initial reduction in hind-limb size.
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Affiliation(s)
- J G M Thewissen
- Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA.
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155
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Togi K, Yoshida Y, Matsumae H, Nakashima Y, Kita T, Tanaka M. Essential role of Hand2 in interventricular septum formation and trabeculation during cardiac development. Biochem Biophys Res Commun 2006; 343:144-51. [PMID: 16530167 DOI: 10.1016/j.bbrc.2006.02.122] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Accepted: 02/17/2006] [Indexed: 10/25/2022]
Abstract
Interventricular septum (IVS) formation is one of the key events in the development of a four-chambered heart. We previously showed that the basic helix-loop-helix transcription factor Hand1 plays an important role in the formation of the IVS. Here, we found that the other Hand gene, Hand2, regulated expansion, trabeculation, and IVS formation in the embryonic heart. In transgenic embryos expressing Hand2 in the whole ventricles, the boundary region between the left and right ventricles expanded outwards, resulting in complete absence of the IVS. Moreover, trabecular formation was observed even in a region where the IVS was expected to form. In some transgenic embryos with heterogeneous expression of the transgene, a muscular septum did not form in a region where Hand2 was expressed, but an incomplete septum was identifiable in a region where Hand2 was not expressed, suggesting that septum formation was strictly regulated by the expression domain of Hand2. Furthermore, expression of trabecular markers including ANF, BNP, and connexin40 was significantly up-regulated in the ventricles of Hand2 transgenic embryos as well as in H9c2 cells over-expressing Hand2. These results suggested that the absence of Hand2 expression in the interventricular boundary region inhibits expansion and trabeculation in this area, contributing to the proper formation of the IVS.
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Affiliation(s)
- Kiyonori Togi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Japan
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156
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Wenzlau JM, Garl PJ, Simpson P, Stenmark KR, West J, Artinger KB, Nemenoff RA, Weiser-Evans MCM. Embryonic Growth-Associated Protein Is One Subunit of a Novel N-Terminal Acetyltransferase Complex Essential for Embryonic Vascular Development. Circ Res 2006; 98:846-55. [PMID: 16484612 DOI: 10.1161/01.res.0000214539.86593.7a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
N-terminal protein acetylation, catalyzed by N-terminal acetyltransferases (NATs) recognizing distinct N-terminal sequences, is gaining recognition as an essential regulator of normal cell function, but little is known of its role in vertebrate development. We previously cloned a novel gene, embryonic growth-associated protein (EGAP), the expression of which is associated with rapid vascular smooth muscle cell proliferation during development. We show herein EGAP is the mammalian/
zebrafish
homologue of yeast Mak10p, one subunit of the yeast NatC complex, and describe the cloning of its binding partners Mak3 and Mak31. The EGAP NAT forms a functional complex in mammalian cells, is evolutionarily conserved, and developmentally regulated. It is widely but not ubiquitously expressed during early
zebrafish
development but undetectable in later developmental stages. We demonstrate EGAP- and Mak3-deficient
zebrafish
fail to develop because of, in part, decreased cell proliferation, increased apoptosis, and poor blood vessel formation contributing to embryonic lethality. We examined the role of target of rapamycin (TOR), a highly conserved protein kinase controlling cell growth, as a physiological target of EGAP NAT acetylation. Compared with controls, TOR expression and signaling is significantly reduced in EGAP morphants. Pharmacological inhibition of TOR with rapamycin phenocopied the EGAP morpholino oligonucleotide-induced growth and vessel defects. Overexpression of constitutively active TOR rescued EGAP morphants, suggesting TOR is a direct or indirect endogenous substrate of the EGAP NAT complex. These data suggest the EGAP NAT complex is an essential regulatory enzyme controlling the function of a subset of proteins required for embryonic growth control and vessel development.
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Affiliation(s)
- Janet M Wenzlau
- Department of Renal Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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157
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Walker MB, Miller CT, Coffin Talbot J, Stock DW, Kimmel CB. Zebrafish furin mutants reveal intricacies in regulating Endothelin1 signaling in craniofacial patterning. Dev Biol 2006; 295:194-205. [PMID: 16678149 DOI: 10.1016/j.ydbio.2006.03.028] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 03/13/2006] [Accepted: 03/20/2006] [Indexed: 11/22/2022]
Abstract
Endothelin1 (Edn1) signaling promotes ventral character to the facial skeleton. In zebrafish edn1 mutants, the ventral jaw structures are severely reduced and fused to their dorsal counterparts, with a loss of joints that normally form at an intermediate dorsal-ventral position. Loss of function at another locus, sturgeon, also yields joint losses, but only mild reductions in the ventral jaw structures. We show that sturgeon encodes one of two orthologs of Furin present in zebrafish, and that both furin genes may function partially redundantly to activate Edn1 signaling. Supporting this hypothesis, early expression of edn1-dependent genes is downregulated in sturgeon (furinA) mutants. Later in development, expression of most of these genes recovers to near wild-type levels in furinA mutants but not in edn1 mutants. The recovery explains the less severe furinA mutant skeletal phenotype and suggests that late gene expression is dependent on a critical level of Edn1 signaling not present in the more severe edn1 mutants. However, expression defects in the intermediate joint-forming domains in both mutants persist, explaining the joint losses observed later in both mutants. We further show that in both mutants the arches fail to correctly undergo ventral elongation before skeletogenesis begins and propose a model in which this failure is largely responsible for the loss of an Edn1-dependent compartmentation of the arch into the intermediate and ventral domains.
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Affiliation(s)
- Macie B Walker
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA.
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158
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Sellin J, Albrecht S, Kölsch V, Paululat A. Dynamics of heart differentiation, visualized utilizing heart enhancer elements of the Drosophila melanogaster bHLH transcription factor Hand. Gene Expr Patterns 2006; 6:360-75. [PMID: 16455308 DOI: 10.1016/j.modgep.2005.09.012] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 09/25/2005] [Indexed: 11/27/2022]
Abstract
Drosophila melanogaster has become one of the important model systems to investigate the development and differentiation of the heart. After 24h after egg deposition (h AED), a simple tube-like organ is formed, consisting of essentially only two cell types, the contractile cardioblasts and non-myogenic pericardial cells. In contrast to the detailed knowledge of heart formation during embryogenesis, only a few studies deal with later changes in heart morphology and/or function. This is mainly due to the difficulties to carry out whole mount stainings in later stages without complicated dissections or treatments of the cuticle and puparium. In this paper we describe the identification of a hand genomic region, which is fully sufficient to drive GFP expression in heart cells of embryos, larvae, and adults. This serves as an initial step to understand the position of hand in the early regulatory network in heart development. Furthermore, we demonstrate that our newly created GFP reporter line is extremely useful to study postembryonic heart differentiation. For the first time we document heart differentiation in living animals throughout all developmental stages of Drosophila melanogaster, including embryogenesis, all three larval stages, metamorphosis, and the adult life with respect to pericardial cells and cardiomyocytes.
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Affiliation(s)
- Julia Sellin
- Universität Osnabrück, Fachbereich Biologie/Chemie - Zoologie, Barbarastrasse 11, 49069 Osnabrück, Germany
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159
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Collop AH, Broomfield JA, Chandraratna RA, Yong Z, Deimling SJ, Kolker SJ, Weeks DL, Drysdale TA. Retinoic acid signaling is essential for formation of the heart tube in Xenopus. Dev Biol 2006; 291:96-109. [PMID: 16423341 PMCID: PMC3539789 DOI: 10.1016/j.ydbio.2005.12.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 11/30/2005] [Accepted: 12/06/2005] [Indexed: 12/23/2022]
Abstract
Retinoic acid is clearly important for the development of the heart. In this paper, we provide evidence that retinoic acid is essential for multiple aspects of cardiogenesis in Xenopus by examining embryos that have been exposed to retinoic acid receptor antagonists. Early in cardiogenesis, retinoic acid alters the expression of key genes in the lateral plate mesoderm including Nkx2.5 and HAND1, indicating that early patterning of the lateral plate mesoderm is, in part, controlled by retinoic acid. We found that, in Xenopus, the transition of the heart from a sheet of cells to a tube required retinoic acid signaling. The requirement for retinoic acid signaling was determined to take place during a narrow window of time between embryonic stages 14 and 18, well before heart tube closure. At the highest doses used, the lateral fields of myocardium fail to fuse, intermediate doses lead to a fusion of the two sides but failure to form a tube, and embryos exposed to lower concentrations of antagonist form a heart tube that failed to complete all the landmark changes that characterize looping. The myocardial phenotypes observed when exposed to the retinoic acid antagonist resemble the myocardium from earlier stages of cardiogenesis, although precocious expression of cardiac differentiation markers was not seen. The morphology of individual cells within the myocardium appeared immature, closely resembling the shape and size of cells at earlier stages of development. However, the failures in morphogenesis are not merely a slowing of development because, even when allowed to develop through stage 40, the heart tubes did not close when embryos were exposed to high levels of antagonist. Indeed, some aspects of left-right asymmetry also remained even in hearts that never formed a tube. These results demonstrate that components of the retinoic acid signaling pathway are necessary for the progression of cardiac morphogenesis in Xenopus.
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Affiliation(s)
- Andrew H Collop
- Childrens Health Research Institute, 800 Commissioners Rd. E. London, Ontario, Canada N6C 2V5
- Department of Paediatrics, University of Western Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Canada
| | - Joel A.S. Broomfield
- Childrens Health Research Institute, 800 Commissioners Rd. E. London, Ontario, Canada N6C 2V5
- Department of Paediatrics, University of Western Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Canada
| | | | - Zhao Yong
- Childrens Health Research Institute, 800 Commissioners Rd. E. London, Ontario, Canada N6C 2V5
- Department of Paediatrics, University of Western Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Canada
| | - Steven J. Deimling
- Childrens Health Research Institute, 800 Commissioners Rd. E. London, Ontario, Canada N6C 2V5
- Department of Paediatrics, University of Western Ontario, Canada
- Department of Biology, University of Western Ontario, Canada
| | - Sandra J. Kolker
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Daniel L. Weeks
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Thomas A. Drysdale
- Childrens Health Research Institute, 800 Commissioners Rd. E. London, Ontario, Canada N6C 2V5
- Department of Paediatrics, University of Western Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Canada
- Department of Biology, University of Western Ontario, Canada
- Corresponding author. Department of Paediatrics, University of Western Ontario, Canada. Fax: +1 519 685 8186
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160
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Abstract
Congenital heart disease remains a significant cause of morbidity and mortality. In recent years, significant advances in molecular genetics, improved understanding of morphogenesis, recognition of specific patterning of abnormalities within and between species, and the impact of the Human Genome Project have accounted for these advances. Continued rapid developments in genomics and proteomics are anticipated. Epidemiologic investigations continue to be necessary to assess the influence of the environment on genetics. We are on the threshold of influencing the occurrence of congenital heart diseases.
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Affiliation(s)
- Andrew N Pelech
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, PO Box 26509, 8701 Watertown Plank Road, Milwaukee, WI 53266-0509, USA.
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161
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Omi M, Fisher M, Maihle NJ, Dealy CN. Studies on epidermal growth factor receptor signaling in vertebrate limb patterning. Dev Dyn 2005; 233:288-300. [PMID: 15778992 DOI: 10.1002/dvdy.20353] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The epidermal growth factor receptor (EGFR) regulates multiple patterning events in Drosophila limb development, but its role in vertebrate limb morphogenesis has received little attention. The EGFR and several of its ligands are expressed in developing vertebrate limbs in manners consistent with potential patterning roles. To gain insight into functions of EGFR signaling in vertebrate limb development, we expressed a constitutively active EGFR in developing chick limbs in ovo. Expression of activated EGFR causes pre- and postaxial polydactyly, including mirror-image-type digit duplication, likely due to induction of ectopic expression and/or modulation of genes involved in anterior-posterior (AP) patterning such as Sonic hedgehog (Shh), dHand, Patched (Ptc), Gli3, Hoxd13, Hoxd11, bone morphogenetic protein 2 (Bmp2), Gremlin, and FGF4. Activation of EGFR signaling dorsalizes the limb and alters expression of the dorsal-ventral (DV) patterning genes Wnt7a, Lmx, and En1. Ectopic and/or extended FGF8 expressing apical ectodermal ridges (AERs) are also seen. Interdigital regression is inhibited and the digits fail to separate, leading to syndactyly, likely due to antiapoptotic and pro-proliferative effects of activated EGFR signaling on limb mesoderm, and/or attenuation of interdigital Bmp4 expression. These findings suggest potential roles for EGFR signaling in AP and DV patterning, AER formation, and cell survival during limb morphogenesis.
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Affiliation(s)
- Minoru Omi
- Center for Limb and Skeletal Development, Department of BioStructure and Function, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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162
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Morin S, Pozzulo G, Robitaille L, Cross J, Nemer M. MEF2-dependent Recruitment of the HAND1 Transcription Factor Results in Synergistic Activation of Target Promoters. J Biol Chem 2005; 280:32272-8. [PMID: 16043483 DOI: 10.1074/jbc.m507640200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HAND proteins are tissue-restricted members of the basic helix-loop-helix transcription factor family that play critical roles in cell differentiation and organogenesis including placental, cardiovascular, and craniofacial development. Nevertheless, the molecular basis underlying the developmental action of HAND proteins remains undefined. Within the embryo, HAND1 is first detected in the developing heart where it becomes restricted to the atrial and left ventricular compartments, a pattern identical to that of the Nppa gene, which encodes atrial natriuretic factor, the major secretory product of the heart. We hereby report that the cardiac atrial natriuretic factor promoter is directly activated by HAND1, making it the first known HAND1 transcriptional target. The action of HAND1 does not require heterodimerization with class I basic helix-loop-helix factors or DNA binding through E-box elements. Instead, HAND1 is recruited to the promoter via physical interaction with MEF2 proteins. MEF2/HAND1 interaction results in synergistic activation of MEF2-dependent promoters, and MEF2 binding sites are sufficient to mediate this synergy. MEF2 binding to DNA is not enhanced in the presence of HAND1. Instead, cooperativity likely results from corecruitment of co-activators such as CREB-binding protein. The related HAND2 protein can also synergize with MEF2. Thus, HAND proteins act as cell-specific developmental co-activators of the MEF2 family of transcription factors. These findings identify a novel mechanism for HAND action in the heart and provide a general paradigm to understand the mechanism of HAND action in organogenesis.
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Affiliation(s)
- Steves Morin
- Laboratory of Cardiac Growth and Differentiation, Institut de Recherches Cliniques de Montréal (IRCM), Quebec, Canada
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163
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Zhao Y, Samal E, Srivastava D. Serum response factor regulates a muscle-specific microRNA that targets Hand2 during cardiogenesis. Nature 2005; 436:214-20. [PMID: 15951802 DOI: 10.1038/nature03817] [Citation(s) in RCA: 1222] [Impact Index Per Article: 64.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Accepted: 05/17/2005] [Indexed: 12/26/2022]
Abstract
Gradients of signalling and transcription factors govern many aspects of embryogenesis, highlighting the need for spatiotemporal control of regulatory protein levels. MicroRNAs are phylogenetically conserved small RNAs that regulate the translation of target messenger RNAs, providing a mechanism for protein dose regulation. Here we show that microRNA-1-1 (miR-1-1) and miR-1-2 are specifically expressed in cardiac and skeletal muscle precursor cells. We found that the miR-1 genes are direct transcriptional targets of muscle differentiation regulators including serum response factor, MyoD and Mef2. Correspondingly, excess miR-1 in the developing heart leads to a decreased pool of proliferating ventricular cardiomyocytes. Using a new algorithm for microRNA target identification that incorporates features of RNA structure and target accessibility, we show that Hand2, a transcription factor that promotes ventricular cardiomyocyte expansion, is a target of miR-1. This work suggests that miR-1 genes titrate the effects of critical cardiac regulatory proteins to control the balance between differentiation and proliferation during cardiogenesis.
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Affiliation(s)
- Yong Zhao
- Department of Pediatrics (Cardiology), University of Texas Southwestern Medical Center and Children's Medical Center Dallas, 6000 Harry Hines Boulevard, Dallas, Texas 75390-9148, USA
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164
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Affiliation(s)
- Jau-Nian Chen
- University of California Los Angeles, Los Angeles, CA, USA
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165
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Trinh LA, Yelon D, Stainier DYR. Hand2 regulates epithelial formation during myocardial diferentiation. Curr Biol 2005; 15:441-6. [PMID: 15786591 DOI: 10.1016/j.cub.2004.12.083] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Myocardial differentiation is initiated by the activation of terminal-differentiation gene expression within a subset of cells in the anterior lateral plate mesoderm. We have previously shown that shortly after this activation, myocardial cells undergo epithelial maturation [1], suggesting that myocardial differentiation encompasses both molecular and cellular changes. To address the question of how the molecular programs driving myocardial gene expression and the formation of the myocardial epithelium are integrated, we analyzed the role of two essential myocardial terminal-differentiation factors, Hand2 and Gata5, in myocardial epithelia formation. hand2 and gata5 mutants exhibit a much-reduced number of myocardial cells and defects in myocardial gene expression [2,3]. We find that the few myocardial precursors that are present in hand2 mutants do not polarize. In contrast, embryos with reduced Gata5 function exhibit polarized myocardial epithelia despite a similar reduction in myocardial precursor number, indicating that proper cell number is not required for epithelial formation. Taken thogether, these results indicate that Hand2 is uniquely required for myocardial polarization, a previously unappreciated role for this critical transcription factor. Furthermore, these results demonstrate that two independent processes, the polarizaton of myocardial precursors and the allocation of proper cell number, contribute to myocardial development.
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Affiliation(s)
- Le A Trinh
- Department of Biochemistry and Biophysics Programs in Developmental Biology, Genetics, and Human Genetics, University of California, San Francisco, San Francisco, California 94143, USA
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166
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Brott BK, Sokol SY. A Vertebrate Homolog of the Cell Cycle Regulator Dbf4 Is an Inhibitor of Wnt Signaling Required for Heart Development. Dev Cell 2005; 8:703-15. [PMID: 15866161 DOI: 10.1016/j.devcel.2005.02.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 01/24/2005] [Accepted: 02/11/2005] [Indexed: 11/21/2022]
Abstract
Early stages of vertebrate heart development have been linked to Wnt signaling. Here we show in both gain- and loss-of-function experiments that XDbf4, a known regulator of Cdc7 kinase, is an inhibitor of the canonical Wnt signaling pathway. Depletion of endogenous XDbf4 protein did not disturb gastrulation movements or early organizer genes but resulted in embryos with morphologically defective heart and eyes and suppressed cardiac markers. These markers were restored by overexpressed XDbf4, or an XDbf4 mutant that inhibits Wnt signaling but lacks the ability to regulate Cdc7. This indicates that the function of XDbf4 in heart development is independent of its role in the cell cycle. Moreover, our data suggest that XDbf4 acts through the physical and functional interaction with Frodo, a context-dependent regulator of Wnt signaling. These findings establish an unexpected function for a vertebrate Dbf4 homolog and demonstrate the requirement for Wnt inhibition in early cardiac specification.
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Affiliation(s)
- Barbara K Brott
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02215, USA
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167
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Tickle C. The contribution of chicken embryology to the understanding of vertebrate limb development. Mech Dev 2005; 121:1019-29. [PMID: 15296968 DOI: 10.1016/j.mod.2004.05.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Revised: 05/25/2004] [Accepted: 05/25/2004] [Indexed: 11/28/2022]
Abstract
The chicken is an excellent model organism for studying vertebrate limb development, mainly because of the ease of manipulating the developing limb in vivo. Classical chicken embryology has provided fate maps and elucidated the cell-cell interactions that specify limb pattern. The first defined chemical that can mimic one of these interactions was discovered by experiments on developing chick limbs and, over the last 15 years or so, the role of an increasing number of developmentally important genes has been uncovered. The principles that underlie limb development in chickens are applicable to other vertebrates and there are growing links with clinical genetics. The sequence of the chicken genome, together with other recently assembled chicken genomic resources, will present new opportunities for exploiting the ease of manipulating the limb.
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Affiliation(s)
- C Tickle
- Division of Cell and Developmental Biology, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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168
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Firulli BA, Krawchuk D, Centonze VE, Vargesson N, Virshup DM, Conway SJ, Cserjesi P, Laufer E, Firulli AB. Altered Twist1 and Hand2 dimerization is associated with Saethre-Chotzen syndrome and limb abnormalities. Nat Genet 2005; 37:373-81. [PMID: 15735646 PMCID: PMC2568820 DOI: 10.1038/ng1525] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2004] [Accepted: 01/10/2005] [Indexed: 02/06/2023]
Abstract
Autosomal dominant mutations in the gene encoding the basic helix-loop-helix transcription factor Twist1 are associated with limb and craniofacial defects in humans with Saethre-Chotzen syndrome. The molecular mechanism underlying these phenotypes is poorly understood. We show that ectopic expression of the related basic helix-loop-helix factor Hand2 phenocopies Twist1 loss of function in the limb and that the two factors have a gene dosage-dependent antagonistic interaction. Dimerization partner choice by Twist1 and Hand2 can be modulated by protein kinase A- and protein phosphatase 2A-regulated phosphorylation of conserved helix I residues. Notably, multiple Twist1 mutations associated with Saethre-Chotzen syndrome alter protein kinase A-mediated phosphorylation of Twist1, suggesting that misregulation of Twist1 dimerization through either stoichiometric or post-translational mechanisms underlies phenotypes of individuals with Saethre-Chotzen syndrome.
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Affiliation(s)
- Beth A Firulli
- Wells Center for Pediatric Research, James Whitcomb Riley Hospital for Children, Department of Pediatrics, Indiana Medical School, 1044 W. Walnut R4 371, Indianapolis, Indiana 46202-5225, USA.
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169
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Matsui T, Raya A, Kawakami Y, Callol-Massot C, Capdevila J, Rodríguez-Esteban C, Izpisúa Belmonte JC. Noncanonical Wnt signaling regulates midline convergence of organ primordia during zebrafish development. Genes Dev 2005; 19:164-75. [PMID: 15630025 PMCID: PMC540234 DOI: 10.1101/gad.1253605] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Several components of noncanonical Wnt signaling pathways are involved in the control of convergence and extension (CE) movements during zebrafish and Xenopus gastrulation. However, the complexity of these pathways and the wide patterns of expression and activity displayed by some of their components immediately suggest additional morphogenetic roles beyond the control of CE. Here we show that the key modular intracellular mediator Dishevelled, through a specific activation of RhoA GTPase, controls the process of convergence of endoderm and organ precursors toward the embryonic midline in the zebrafish embryo. We also show that three Wnt noncanonical ligands wnt4a, silberblick/wnt11, and wnt11-related regulate this process by acting in a largely redundant way. The same ligands are also required, nonredundantly, to control specific aspects of CE that involve interaction of Dishevelled with mediators different from that of RhoA GTPase. Overall, our results uncover a late, previously unexpected role of noncanonical Wnt signaling in the control of midline assembly of organ precursors during vertebrate embryo development.
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Affiliation(s)
- Takaaki Matsui
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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170
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Clouthier DE, Schilling TF. Understanding endothelin-1 function during craniofacial development in the mouse and zebrafish. ACTA ACUST UNITED AC 2005; 72:190-9. [PMID: 15269892 DOI: 10.1002/bdrc.20007] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Morphogenesis of the face and neck is driven by an intricate relay of signaling molecules and transcription factors organized into hierarchical pathways. The coordinated action of these pathways regulates the development of neural crest cells within the pharyngeal arches, resulting in proper spatiotemporal formation of bone, cartilage, and connective tissue. While the functions of many genes involved in these processes were initially elucidated through the use of knockout technology in the mouse, increasing numbers of zebrafish craniofacial mutants have led to a rapid expansion in the identification of genes involved in craniofacial development. A comparative analysis of signaling pathways involved in these processes between mouse and zebrafish holds the potential not only to pinpoint conserved and therefore crucial gene functions in craniofacial development, but also to rapidly identify and study downstream effectors. These complementary approaches will also allow rapid identification of candidate genes and gene functions disrupted in human craniofacial dysmorphologies. In this brief review, we present a comparative analysis of one molecule involved in craniofacial development, endothelin-1, a small, secreted protein that is crucial for patterning the neural crest cells that give rise to lower jaw and throat structures.
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Affiliation(s)
- David E Clouthier
- Department of Molecular, Cellular and Craniofacial Biology, University of Louisville, Kentucky 40292, USA.
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171
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Heicklen-Klein A, McReynolds LJ, Evans T. Using the zebrafish model to study GATA transcription factors. Semin Cell Dev Biol 2004; 16:95-106. [PMID: 15659344 DOI: 10.1016/j.semcdb.2004.10.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The zebrafish is an established animal model system that profits from the availability of strong experimental approaches in both genetics and embryology. As a vertebrate, zebrafish can be used to model many aspects of human development and disease. GATA transcription factors play important roles in the development of many organ systems, including those for hematopoietic, cardiovascular, reproductive, and gut-endoderm derived tissues. The six vertebrate GATA factors are highly conserved in zebrafish at the level of sequence, expression pattern, and function. The identification of mutants, establishment of transgenic GFP reporter fish, and the ease of performing loss- and gain-of-function experiments have all contributed new insight into our understanding of the regulation and function of GATA factors. We review recent advances toward this goal using the zebrafish system with a focus on hematopoiesis and cardiogenesis, and suggest how comparative genetics using the zebrafish genes might reveal core conserved properties, as well as changes in gene function that reflect different morphogenetic programs utilized by various vertebrate embryos.
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Affiliation(s)
- Alice Heicklen-Klein
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Chanin Room 501, Bronx, NY 10461, USA
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172
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Abstract
The basic helix-loop-helix proteins form a special group of transcription factors unique for the eukaryotic organisms. They are crucial for the embryonic development of many fundamental organ systems such as muscle, heart, central nervous system, hematopoiteic system, and many others. They are very flexible in terms of regulating transcription in that they can either promote or repress transcription, and do so in many different ways. Basic helix-loop-helix proteins can form homo- or heterodimers with other members of the group, and are subject to post-transcriptional modifications. In this review, an overview of basic helix-loop-helix protein classification, biochemical function, and examples of past and recent advances in our understanding of embryonic development are presented, with emphasis on the vertebrate muscle, heart, brain, and eye.
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Affiliation(s)
- Tord Hjalt
- Department for Cell and Molecular Biology, Lund University, SE-221 84 Lund, Sweden
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173
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Abstract
Zebrafish have emerged as a useful vertebrate model system in which unbiased large-scale screens have revealed hundreds of mutations affecting vertebrate development. Many zebrafish mutants closely resemble known human disorders, thus providing intriguing prospects for uncovering the genetic basis of human diseases and for the development of pharmacologic agents that inhibit or correct the progression of developmental disorders. The rapid pace of advances in genomic sequencing and map construction, in addition to morpholino targeting and transgenic techniques, have facilitated the identification and analysis of genes associated with zebrafish mutants, thus promoting the development of zebrafish as a model for human disorders. This review aims to illustrate how the zebrafish has been used to identify unknown genes, to assign function to known genes, and to delineate genetic pathways, all contributing valuable leads toward understanding human pathophysiology.
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Affiliation(s)
- Trista E North
- Division of Hematology/Oncology, Department of Medicine, Children's Hospital of Boston, Enders Research Building, Boston, Massachusetts 02115, USA
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174
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Nambiar RM, Henion PD. Sequential antagonism of early and late Wnt-signaling by zebrafish colgate promotes dorsal and anterior fates. Dev Biol 2004; 267:165-80. [PMID: 14975724 DOI: 10.1016/j.ydbio.2003.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Revised: 11/10/2003] [Accepted: 11/11/2003] [Indexed: 10/26/2022]
Abstract
The establishment of the vertebrate body plan involves patterning of the ectoderm, mesoderm, and endoderm along the dorsoventral and antero-posterior axes. Interactions among numerous signaling molecules from several multigene families, including Wnts, have been implicated in regulating these processes. Here we provide evidence that the zebrafish colgate(b382) (col) mutation results in increased Wnt signaling that leads to defects in dorsal and anterior development. col mutants display early defects in dorsoventral patterning manifested by a decrease in the expression of dorsal shield-specific markers and ectopic expression of ventrolaterally expressed genes during gastrulation. In addition to these early patterning defects, col mutants display a striking regional posteriorization within the neuroectoderm, resulting in a reduction in anterior fates and an expansion of posterior fates within the forebrain and midbrain-hindbrain regions. We are able to correlate these phenotypes to the overactivation of Wnt signaling in col mutants. The early dorsal and anterior patterning phenotypes of the col mutant embryos are selectively rescued by inactivation of Wnt8 function by morpholino translational interference. In contrast, the regionalized neuroectoderm posterioriorization phenotype is selectively rescued by morpholino-mediated inactivation of Wnt8b. These results suggest that col-mediated antagonism of early and late Wnt-signaling activity during gastrulation is normally required sequentially for both early dorsoventral patterning and the specification and patterning of regional fates within the anterior neuroectoderm.
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Affiliation(s)
- Roopa M Nambiar
- Molecular, Cellular and Developmental Biology Program, Center for Molecular Neurobiology, Ohio State University, Columbus, OH 43210, USA
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175
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Trinh LA, Stainier DYR. Fibronectin regulates epithelial organization during myocardial migration in zebrafish. Dev Cell 2004; 6:371-82. [PMID: 15030760 DOI: 10.1016/s1534-5807(04)00063-2] [Citation(s) in RCA: 260] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Revised: 01/20/2004] [Accepted: 01/21/2004] [Indexed: 10/26/2022]
Abstract
Several genes have been implicated in heart tube formation, yet we know little about underlying cellular mechanisms. We analyzed the cellular architecture of the migrating myocardial precursors, and find that they form coherent epithelia that mature as they move medially. Mutant analyses indicate that the cardia bifida locus natter (nat) is required for the integrity of the myocardial epithelia. We positionally cloned nat and show that it encodes Fibronectin. During myocardial migration, Fibronectin is deposited at the midline between the endoderm and endocardial precursors, and laterally around the myocardial precursors. Further analyses show that Fibronectin deposition at the midline is required for the timely migration of myocardial precursors, but dispensable for the migration process itself. In the complete absence of Fibronectin, adherens junctions between myocardial precursors do not form properly, suggesting that cell-substratum interactions are required for epithelial organization. These data suggest that myocardial migration is dependent on epithelial integrity.
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Affiliation(s)
- L A Trinh
- Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics and Human Genetics, University of California, San Francisco, San Francisco, CA 94143, USA
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176
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Mably JD, Mohideen MAPK, Burns CG, Chen JN, Fishman MC. heart of glass regulates the concentric growth of the heart in zebrafish. Curr Biol 2004; 13:2138-47. [PMID: 14680629 DOI: 10.1016/j.cub.2003.11.055] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Patterned growth of vertebrate organs is essential for normal physiological function, but the underlying pathways that govern organotypic growth are not clearly understood. Heart function is critically dependent upon the concentric thickening of the ventricular wall generated by the addition of cells to the myocardium along the axis from the endocardium (inside) to the outside of the chamber. In heart of glass mutant embryos, the number of cells in the myocardium is normal, but they are not added in the concentric direction. As a consequence, the chambers are huge and dysfunctional, and the myocardium remains a single layer. RESULTS To begin to define the factors controlling the concentric growth of cells in the myocardium, we used positional cloning to identify the heart of glass (heg) gene. heg encodes a protein of previously undescribed function, expressed in the endocardial layer of the heart. By alternative splicing, three distinct isoforms are generated, one of which is predicted to be transmembrane and two other secreted. By selective morpholino perturbation, we demonstrate that the transmembrane form is critical for the normal pattern of growth. CONCLUSIONS heart of glass encodes a previously uncharacterized endocardial signal that is vital for patterning concentric growth of the heart. Growth of the heart requires addition of myocardial cells along the endocardial-to-myocardial axis. This axis of patterning is driven by heg, a novel transmembrane protein expressed in the endocardium.
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Affiliation(s)
- John D Mably
- Cardiovascular Research Center, Massachusetts General Hospital and Department of Medicine, Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA.
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177
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Affiliation(s)
- Le A Trinh
- Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics, and Human Genetics, University of California, San Francisco, California 94143-0448, USA
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178
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Stewart RA, Look AT, Kanki JP, Henion PD. Development of the peripheral sympathetic nervous system in zebrafish. Methods Cell Biol 2004; 76:237-60. [PMID: 15602879 DOI: 10.1016/s0091-679x(04)76012-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Rodney A Stewart
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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179
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Affiliation(s)
- Yashar Javidan
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California 92697, USA
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180
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Srivastava D, Gottlieb PD, Olson EN. Molecular mechanisms of ventricular hypoplasia. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 67:121-5. [PMID: 12858532 DOI: 10.1101/sqb.2002.67.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have established the beginnings of a road map to understand how ventricular cells become specified, differentiate, and expand into a functional cardiac chamber (Fig. 5). The transcriptional networks described here provide clear evidence that disruption of pathways affecting ventricular growth could be the underlying etiology in a subset of children born with malformation of the right or left ventricle. As we learn details of the precise mechanisms through which the critical factors function, the challenge will lie in devising innovative methods to augment or modify the effects of gene mutations on ventricular development. Because most congenital heart disease likely occurs in a setting of heterozygous, predisposing mutations of one or more genes, modulation of activity of critical pathways in a preventive fashion may be useful in averting disease in genetically susceptible individuals.
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Affiliation(s)
- D Srivastava
- Departments of Pediatrics and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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181
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Affiliation(s)
- Eric N Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA.
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182
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Firulli AB. A HANDful of questions: the molecular biology of the heart and neural crest derivatives (HAND)-subclass of basic helix-loop-helix transcription factors. Gene 2003; 312:27-40. [PMID: 12909338 DOI: 10.1016/s0378-1119(03)00669-3] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The HAND subclass of basic Helix-loop-helix factors is comprised of two members HAND1 and HAND2. HAND genes are present within the genomes of organisms ranging from flies to man. Experiments employing chick embryology, tissue culture, and gene targeting in mice show that HAND function is critical for the specification and/or differentiation of extraembryonic structures that include the yolk sac, placenta, and the cells of the trophoblast lineages. HAND factors also play key roles in cardiac, gut, sympathetic neuronal development and in the proper development of tissues populated by HAND-expressing neural crest cells, including regions of the developing vasculature, the limbs, the jaw, and teeth. Surprisingly, nearly 10 years after their initial identification and characterization, little is understood about the nature of the downstream target genes which HAND1 and HAND2 regulate, whether the nature of their transcriptional regulation is positive or negative, or if they modulate genetic programs common to these diverse tissue types or if they drive unique subsets of genes that contribute to tissue identity. At the core of these questions is by which mechanisms do HAND factors modulate biological activity? Do they behave like classical class B bHLH factors or is their function more complex requiring a rethinking of the dogma? What follows is a review of what is currently known about HAND factors and a reflection on why elucidating their role in the biological programs within which they participate has been so difficult.
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Affiliation(s)
- Anthony B Firulli
- Wells Center for Pediatric Research, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, 702 Barnhill Drive, Room 2666, Indianapolis, IN 46202-5225, USA.
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183
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Abstract
Cell signaling plays a key role in the development of all multicellular organisms. Numerous studies have established the importance of Hedgehog signaling in a wide variety of regulatory functions during the development of vertebrate and invertebrate organisms. Several reviews have discussed the signaling components in this pathway, their various interactions, and some of the general principles that govern Hedgehog signaling mechanisms. This review focuses on the developing systems themselves, providing a comprehensive survey of the role of Hedgehog signaling in each of these. We also discuss the increasing significance of Hedgehog signaling in the clinical setting.
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Affiliation(s)
- Andrew P McMahon
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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184
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Abstract
The heart develops from two bilateral heart fields that are formed during early gastrulation. In recent years, signaling pathways that specify cardiac mesoderm have been extensively analyzed. In addition, a battery of transcription factors that regulate different aspects of cardiac morphogenesis and cytodifferentiation have been identified and characterized in model organisms. At the anterior pole, a secondary heart field is formed, which in its molecular make-up, appears to be similar to the primary heart field. The cardiac outflow tract and the right ventricle to a large extent are derivatives of this anterior heart field. Cardiac mesoderm receives positional information by which it is patterned along the three body axes. The molecular control of left-right axis development has received particular attention, and the underlying regulatory network begins to emerge. Cardiac chamber development involves the activation of a transcription program that is different from the one present in the primary heart field and regulates cardiac morphogenesis in a region-specific manner. This review also attempts to identify areas in which additional research is needed to fully understand early cardiac development.
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Affiliation(s)
- Thomas Brand
- Department of Cell and Molecular Biology, Technical University of Braunschweig, 38106 Braunschweig, Germany.
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185
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Abstract
In birds and mammals, cardiac neural crest is essential for heart development and contributes to conotruncal cushion formation and outflow tract septation. The zebrafish prototypical heart lacks outflow tract septation, raising the question of whether cardiac neural crest exists in zebrafish. Here, results from three distinct lineage-labeling approaches identify zebrafish cardiac neural crest cells and indicate that these cells have the ability to generate MF20-positive muscle cells in the myocardium of the major chambers during development. Fate-mapping demonstrates that cardiac neural crest cells originate both from neural tube regions analogous to those found in birds, as well as from a novel region rostral to the otic vesicle. In contrast to other vertebrates, cardiac neural crest invades the myocardium in all segments of the heart, including outflow tract, atrium, atrioventricular junction, and ventricle in zebrafish. Three distinct groups of premigratory neural crest along the rostrocaudal axis have different propensities to contribute to different segments in the heart and are correspondingly marked by unique combinations of gene expression patterns. Zebrafish will serve as a model for understanding interactions between cardiac neural crest and cardiovascular development.
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Affiliation(s)
- Mariko Sato
- Huntsman Cancer Institute Center for Children, Departments of Oncological Sciences and Pediatrics, University of Utah, Salt Lake City, UT 84112, USA
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186
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187
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Brand T, Andrée B, Schlange T. Molecular characterization of early cardiac development. Results Probl Cell Differ 2003; 38:215-38. [PMID: 12132397 DOI: 10.1007/978-3-540-45686-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Thomas Brand
- Institute of Biochemistry and Biotechnology, Department of Cell and Molecular Biology, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
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188
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Abstract
Genetic screens in Drosophila melanogaster, Caenorhabditis elegans, and Danio rerio clarified the logic of metazoan development by revealing critical unitary steps and pathways to embryogenesis. Can genetic screens similarly organize medicine? We here examine human diseases that resemble mutations in Danio rerio, the zebrafish, the one vertebrate species for which large-scale genetic screens have been performed and extensively analyzed. Zebrafish mutations faithfully phenocopy many human disorders. Each mutation, once cloned, provides candidate genes and pathways for evaluation in the human. The collection of mutations in their entirety potentially provides a medical taxonomy, one based in developmental biology and genetics.
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Affiliation(s)
- Jordan T Shin
- Cardiovascular Research Center and Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA.
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189
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Abstract
Organogenesis is a dynamic process involving multiple phases of pattern formation and morphogenesis. For example, heart formation involves the specification and differentiation of cardiac precursors, the integration of precursors into a tube, and the remodeling of the embryonic tube to create a fully functional organ. Recently, the zebrafish has emerged as a powerful model organism for the analysis of cardiac development. In particular, zebrafish mutations have revealed specific genetic requirements for cardiac fate determination, migration, fusion, tube assembly, looping, and remodeling. These processes ensure proper cardiac function; likewise, cardiac function may influence aspects of cardiac morphogenesis.
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Affiliation(s)
- Nathalia S Glickman
- Developmental Genetics Program and Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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190
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Doitsidou M, Reichman-Fried M, Stebler J, Köprunner M, Dörries J, Meyer D, Esguerra CV, Leung T, Raz E. Guidance of primordial germ cell migration by the chemokine SDF-1. Cell 2002; 111:647-59. [PMID: 12464177 DOI: 10.1016/s0092-8674(02)01135-2] [Citation(s) in RCA: 496] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The signals directing primordial germ cell (PGC) migration in vertebrates are largely unknown. We demonstrate that sdf-1 mRNA is expressed in locations where PGCs are found and toward which they migrate in wild-type as well as in mutant embryos in which PGC migration is abnormal. Knocking down SDF-1 or its receptor CXCR4 results in severe defects in PGC migration. Specifically, PGCs that do not receive the SDF-1 signal exhibit lack of directional movement toward their target and arrive at ectopic positions within the embryo. Finally, we show that the PGCs can be attracted toward an ectopic source of the chemokine, strongly suggesting that this molecule provides a key directional cue for the PGCs.
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Affiliation(s)
- Maria Doitsidou
- Germ Cell Development, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
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191
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Firulli AB, Thattaliyath BD. Transcription factors in cardiogenesis: the combinations that unlock the mysteries of the heart. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 214:1-62. [PMID: 11893163 DOI: 10.1016/s0074-7696(02)14002-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Heart formation is one of the first signs of organogenesis within the developing embryo and this process is conserved from flies to man. Completing the genetic roadmap of the molecular mechanisms that control the cell specification and differentiation of cells that form the developing heart has been an exciting and fast-moving area of research in the fields of molecular and developmental biology. At the core of these studies is an interest in the transcription factors that are responsible for initiation of a pluripotent cell to become programmed to the cardiac lineage and the subsequent transcription factors that implement the instructions set up by the cells commitment decision. To gain a better understanding of these pathways, cardiac-expressed transcription factors have been identified, cloned, overexpressed, and mutated to try to determine function. Although results vary depending on the gene in question, it is clear that there is a striking evolutionary conservation of the cardiogenic program among species. As we move up the evolutionary ladder toward man, we encounter cases of functional redundancy and combinatorial interactions that reflect the complex networks of gene expression that orchestrate heart development. This review focuses on what is known about the transcription factors implicated in heart formation and the role they play in this intricate genetic program.
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Affiliation(s)
- Anthony B Firulli
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio 78229, USA
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192
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Thattaliyath BD, Livi CB, Steinhelper ME, Toney GM, Firulli AB. HAND1 and HAND2 are expressed in the adult-rodent heart and are modulated during cardiac hypertrophy. Biochem Biophys Res Commun 2002; 297:870-5. [PMID: 12359233 DOI: 10.1016/s0006-291x(02)02297-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The HAND basic Helix-Loop-Helix (bHLH) transcription factors are essential for normal cardiac and extraembryonic development. Although highly evolutionarily conserved genes, HAND cardiac expression patterns differ across species. Mouse expression of HAND1 and HAND2 was reported absent in the adult heart. Human HAND genes are expressed in the adult heart and HAND1 expression is downregulated in cardiomyopathies. As rodent and human expression profiles are inconsistent, we re-examined expression of HAND1 and HAND2 in adult-rodent hearts. HAND1 and HAND2 are expressed in adult-rodent hearts and HAND2 is expressed in the atria. Induction of cardiac hypertrophy shows modulation of HAND expression, corresponding with observations in human cardiomyopathy. The downregulation of HAND expression observed in rodent hypertrophy and human cardiomyopathy may reflect a permissive role allowing, cardiomyocytes to reinitiate the fetal gene program and initiate the adaptive physiological changes that allow the heart to compensate (hypertrophy) for the increase in afterload.
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Affiliation(s)
- Bijoy D Thattaliyath
- Department of Physiology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, Mail Code-7756, San Antonio, TX 78229-3900, USA
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193
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194
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Abstract
The mammalian heart is crafted from a few progenitor cells that are subject to rapidly changing sets of instructions from their environment and from within. These instructions cause them to migrate, expand and diversify in lineage, and acquire form and function. Molecular information from various model systems, combined with increasingly detailed morphogenetic data, has provided insights into some of these key events. Many congenital heart abnormalities might arise from defects in the early stages of heart development, therefore it is important to understand the molecular pathways that underlie the lineage specification and patterning processes that shape this organ.
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Affiliation(s)
- Richard P Harvey
- Victor Chang Institute of Medical Research, 384 Victoria Street, Darlinghurst 2010, New South Wales, Australia.
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195
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Cripps RM, Olson EN. Control of cardiac development by an evolutionarily conserved transcriptional network. Dev Biol 2002; 246:14-28. [PMID: 12027431 DOI: 10.1006/dbio.2002.0666] [Citation(s) in RCA: 232] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Formation of the heart is dependent on an intricate cascade of developmental decisions. Analysis of the molecules and mechanisms involved in the specification of cardiac cell fates, differentiation and diversification of cardiac muscle cells, and morphogenesis and patterning of different cardiac cell types has revealed an evolutionarily conserved network of signaling pathways and transcription factors that underlies these processes. The regulatory network that controls the formation of the primitive heart in fruit flies has been elaborated upon to form the complex multichambered heart of mammals. We compare and contrast the mechanisms involved in heart formation in fruit flies and mammals in the context of a network of transcriptional interactions and point to unresolved questions for the future.
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Affiliation(s)
- Richard M Cripps
- Department of Biology, University of New Mexico, Albuquerque 87131-1091, USA.
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196
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Stainier DY. Contribution du poisson zèbre à l’étude moléculaire du développement du cœur des vertébrés. Med Sci (Paris) 2002. [DOI: 10.1051/medsci/2002184448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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197
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Abstract
Transcription factors can regulate the expression of other genes in a tissue-specific and quantitative manner and are thus major regulators of embryonic developmental processes. Several transcription factors that regulate cardiac genes specifically have been described, and the recent discovery that dominant inherited transcription factor mutations cause congenital heart defects in humans has brought direct medical relevance to the study of cardiac transcription factors in heart development. Although this field of study is extensive, several major gaps in our knowledge of the transcriptional control of heart development still exist. This review will concentrate on recent developments in the field of cardiac transcription factors and their roles in heart formation.
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Affiliation(s)
- Benoit G Bruneau
- Division of Cardiovascular Research and Programme in Developmental Biology, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
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198
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te Welscher P, Fernandez-Teran M, Ros MA, Zeller R. Mutual genetic antagonism involving GLI3 and dHAND prepatterns the vertebrate limb bud mesenchyme prior to SHH signaling. Genes Dev 2002; 16:421-6. [PMID: 11850405 PMCID: PMC155343 DOI: 10.1101/gad.219202] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The bHLH transcription factor dHAND is required for establishment of SHH signaling by the limb bud organizer in posterior mesenchyme, a step crucial to development of vertebrate paired appendages. We show that the transcriptional repressor GLI3 restricts dHAND expression to posterior mesenchyme prior to activation of SHH signaling in mouse limb buds. dHAND, in turn, excludes anterior genes such as Gli3 and Alx4 from posterior mesenchyme. Furthermore, genetic interaction of GLI3 and dHAND directs establishment of the SHH/FGF signaling feedback loop by restricting the BMP antagonist GREMLIN posteriorly. These interactions polarize the nascent limb bud mesenchyme prior to SHH signaling.
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Affiliation(s)
- Pascal te Welscher
- Department of Developmental Biology, Faculty of Biology, Utrecht University, 3584CH Utrecht, The Netherlands
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Abstract
Organs are specialized tissues used for enhanced physiology and environmental adaptation. The cells of the embryo are genetically programmed to establish organ form and function through conserved developmental modules. The zebrafish is a powerful model system that is poised to contribute to our basic understanding of vertebrate organogenesis. This review develops the theme of modules and illustrates how zebrafish have been particularly useful for understanding heart and blood formation.
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Affiliation(s)
- Christine Thisse
- Institut de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université Louis Pasteur, 1 rue Laurent Fries, BP 163, 67404 Illkirch Cedex, C. U. de Strasbourg, France
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200
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Abstract
Development of the embryonic vertebrate heart requires the precise coordination of pattern formation and cell movement. Taking advantage of the availability of zebrafish mutations that disrupt cardiogenesis, several groups have identified key regulators of specific aspects of cardiac patterning and morphogenesis. Several genes, including gata5, fgf8, bmp2b, one-eyed pinhead, and hand2, have been shown to be relevant to the patterning events that regulate myocardial differentiation. Studies of mutants with morphogenetic defects have indicated at least six genes that are essential for cardiac fusion and heart tube assembly, including casanova, bonnie and clyde, gata5, one-eyed pinhead, hand2, miles apart, and heart and soul. Furthermore, analysis of the jekyll gene has indicated its important role during the morphogenesis of the atrioventricular valve. Altogether, these data provide a substantial foundation for future investigations of cardiac patterning, cardiac morphogenesis, and the relationship between these processes.
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Affiliation(s)
- D Yelon
- Developmental Genetics Program, Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York 10016, USA.
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