51
|
Urban AE, Zhou X, Ungos JM, Raible DW, Altmann CR, Vize PD. FGF is essential for both condensation and mesenchymal-epithelial transition stages of pronephric kidney tubule development. Dev Biol 2006; 297:103-17. [PMID: 16872594 DOI: 10.1016/j.ydbio.2006.04.469] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 04/10/2006] [Accepted: 04/28/2006] [Indexed: 11/25/2022]
Abstract
The pronephros is a transient embryonic kidney that is essential for the survival of aquatic larvae. It is also absolutely critical for adult kidney development, as the pronephric derivative the wolffian duct forms the ductal system of the adult kidney and also triggers the condensation of metanephric mesenchyme into the adult nephrons. While exploring Xenopus pronephric patterning, we observed that epidermally delivered hedgehog completely suppresses pronephric kidney tubule development but does not effect development of the pronephric glomus, the equivalent of the mammalian glomerulus or corpuscle. This effect is not mediated by apoptosis. Microarray analysis of microdissected primordia identified FGF8 as one of the potential mediators of hedgehog action. Further investigation demonstrated that SU5402-sensitive FGF signaling plays a critical role in the very earliest stages of pronephric tubule development. Modulation of FGF8 activity using a morpholino has a later effect that blocks condensation of pronephric mesenchyme into the pronephric tubule. Together, these data show that FGF signaling plays a critical role at two stages of embryonic kidney development, one in the condensation of the pronephric primordium from the intermediate mesoderm and a second in the later epithelialization of this mesenchyme into the pronephric nephron. The data also show that in Xenopus, development of the glomus/glomerulus can be uncoupled from nephron formation via ectopic hedgehog expression and provides an experimental avenue for investigating glomerulogenesis in the complete absence of tubules.
Collapse
Affiliation(s)
- Anna E Urban
- Department of Biological Science, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | | | | | | | | | | |
Collapse
|
52
|
Milan DJ, Giokas AC, Serluca FC, Peterson RT, MacRae CA. Notch1b and neuregulin are required for specification of central cardiac conduction tissue. Development 2006; 133:1125-32. [PMID: 16481353 DOI: 10.1242/dev.02279] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Normal heart function is critically dependent on the timing and coordination provided by a complex network of specialized cells: the cardiac conduction system. We have employed functional assays in zebrafish to explore early steps in the patterning of the conduction system that previously have been inaccessible. We demonstrate that a ring of atrioventricular conduction tissue develops at 40 hours post-fertilization in the zebrafish heart. Analysis of the mutant cloche reveals a requirement for endocardial signals in the formation of this tissue. The differentiation of these specialized cells, unlike that of adjacent endocardial cushions and valves, is not dependent on blood flow or cardiac contraction. Finally, both neuregulin and notch1b are necessary for the development of atrioventricular conduction tissue. These results are the first demonstration of the endocardial signals required for patterning central `slow' conduction tissue, and they reveal the operation of distinct local endocardial-myocardial interactions within the developing heart tube.
Collapse
Affiliation(s)
- David J Milan
- Cardiovascular Research Center and Cardiology Division, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | | | | | | | | |
Collapse
|
53
|
Eng E, Holgren C, Hubchak S, Naaz P, Schnaper HW. Hypoxia regulates PDGF-B interactions between glomerular capillary endothelial and mesangial cells. Kidney Int 2005; 68:695-703. [PMID: 16014047 DOI: 10.1111/j.1523-1755.2005.00448.x] [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: 11/28/2022]
Abstract
BACKGROUND Platelet-derived growth factor (PDGF)-B regulates mesangial cell and vessel development during embryogenesis, and contributes to the pathogenesis of adult renal and vascular diseases. Endothelial cell PDGF-B exerts paracrine effects on mesangial cells, but its regulation is not well defined. We examined the impact of hypoxia on PDGF-B-mediated interactions between glomerular endothelial and mesangial cells, a condition of potential relevance in developing, and diseased adult, kidneys. METHODS Glomerular endothelial or mesangial cells were subjected to hypoxia and responses compared to normoxic cells. Endothelial PDGF-B was studied by Northern and Western analysis. Mesangial proliferative responses to PDGF-B were assessed by (3)H-thymidine incorporation, and migration by a modified Boyden chamber assay. Hypoxia-induced changes in receptor specific binding capacity were studied by saturation binding assays. RESULTS Hypoxia stimulated increases in endothelial PDGF-B mRNA and protein. In normoxic mesangial cells, PDGF-B stimulated dose-dependent proliferation, but the proliferative response of hypoxic cells was two to three times greater. Exogenous PDGF-B also caused prompter migration in hypoxic mesangial cells. Mesangial cells were treated with endothelial cell-conditioned medium. More cells migrated when hypoxic cells were stimulated with hypoxic conditioned medium, than when normoxic cells were stimulated with normoxic conditioned medium. Preincubating conditioned medium with PDGF-B neutralizing antibody greatly decreased the chemoattractant activity. Binding studies demonstrated increased specific binding capacity in hypoxic cells. CONCLUSION Hypoxia enhances PDGF-B paracrine interactions between glomerular endothelial and mesangial cells. These hypoxia-regulated interactions may be important during glomerulogenesis in fetal life and during the pathogenesis of adult glomerular disease.
Collapse
Affiliation(s)
- Eudora Eng
- Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
| | | | | | | | | |
Collapse
|
54
|
Affiliation(s)
- Jau-Nian Chen
- University of California Los Angeles, Los Angeles, CA, USA
| | | | | |
Collapse
|
55
|
Abstract
Unraveling the molecular pathogenesis of human disease presents many experimental challenges, not the least of which is that experiments on humans are generally frowned upon. Model organisms, including the zebrafish, allow for experimental analysis of gene function and the detailed characterization of disease processes. Zebrafish have matured as a vertebrate model organism now that genetic tools for targeted "knockdowns" and unbiased mutagenesis approaches are in hand. The fish larval pronephros is a relevant kidney in which to pursue many aspects of human kidney development and disease. This short review outlines recent progress in applying the zebrafish pronephros to issues of human health and development.
Collapse
Affiliation(s)
- Iain A Drummond
- Department of Medicine, Harvard Medical School and Renal Unit, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
| |
Collapse
|
56
|
Hentschel DM, Park KM, Cilenti L, Zervos AS, Drummond I, Bonventre JV. Acute renal failure in zebrafish: a novel system to study a complex disease. Am J Physiol Renal Physiol 2004; 288:F923-9. [PMID: 15625083 DOI: 10.1152/ajprenal.00386.2004] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute renal failure (ARF) is characterized by a very high mortality essentially unchanged over the past 40 years. Simple vertebrate models are needed to improve our understanding of ARF and facilitate the development of novel therapies for this clinical syndrome. Here, we demonstrate that gentamicin, a commonly used nephrotoxic antibiotic, causes larval zebrafish to develop ARF characterized by histological and functional changes that mirror aminoglycoside toxicity in higher vertebrates and inability of zebrafish to maintain fluid homeostasis. We developed a novel method to quantitate renal function in larval zebrafish and demonstrate a decline in glomerular filtration rate after gentamicin exposure. The antineoplastic drug cisplatin, whose use in humans is limited by kidney toxicity, also causes typical histological changes and a decline in renal function in larval zebrafish. A specific inhibitor of Omi/HtrA2, a serine protease implicated in cisplatin-induced apoptosis, prevented renal failure and increased survival. This protective effect was confirmed in a mouse model of cisplatin-induced nephrotoxicity. Therefore, zebrafish provides a unique model system, amenable to genetic manipulation and drug screening, to explore the pathophysiology of ARF and establish novel therapies with potential use in mammals.
Collapse
Affiliation(s)
- Dirk M Hentschel
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, MA 02115, USA
| | | | | | | | | | | |
Collapse
|
57
|
Affiliation(s)
- Iain A Drummond
- Department of Medicine, Harvard Medical School and Renal Unit, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA
| |
Collapse
|
58
|
Affiliation(s)
- Ondine Cleaver
- Howard Hughes Medical Institute and Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
59
|
Abstract
The kidney can be thought of as the pairing of two tubes: an epithelial tube (the nephron), carrying filtered blood and engaged in ion and water transport; and endothelial tubes (the blood vessels), delivering blood and carrying away recovered solute. The development of the nephron presents several interesting questions. How does an epithelial tube form and how is it patterned into functionally distinct components and segments? What guides the interaction between the vasculature and kidney epithelia? How are epithelial cell shape and lumen diameter maintained, and what goes wrong when kidney tubules balloon into cysts? Here, I outline the progress that has been made in answering these questions using the zebrafish pronephros as a simple, accessible model of nephron development.
Collapse
Affiliation(s)
- Iain Drummond
- Department of Medicine, Harvard Medical School and Renal Unit, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
| |
Collapse
|
60
|
Abstract
Blood vessels perfuse all tissues in the body and mediate vital metabolic exchange between tissues and blood. Increasing evidence, however, points to a direct role for paracrine signaling between blood vessel cells and surrounding target organ cells, during embryonic development and cell differentiation. Understanding the nature of this signaling and its heterogeneity, both in the embryo and in adult tissues, may not only provide insights into mechanisms for normal developmental cell fate decisions, but could also lead to novel targeted therapeutic approaches for a variety of diseases such as heart disease, diabetes or cancer.
Collapse
Affiliation(s)
- Ondine Cleaver
- Howard Hughes Medical Institute and Department of Cellular and Molecular Biology, Harvard University, 7 Divinity Ave, Cambridge, Massachusetts 02138, USA.
| | | |
Collapse
|
61
|
Spitsbergen JM, Kent ML. The state of the art of the zebrafish model for toxicology and toxicologic pathology research--advantages and current limitations. Toxicol Pathol 2003; 31 Suppl:62-87. [PMID: 12597434 PMCID: PMC1909756 DOI: 10.1080/01926230390174959] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The zebrafish (Danio rerio) is now the pre-eminent vertebrate model system for clarification of the roles of specific genes and signaling pathways in development. The zebrafish genome will be completely sequenced within the next 1-2 years. Together with the substantial historical database regarding basic developmental biology, toxicology, and gene transfer, the rich foundation of molecular genetic and genomic data makes zebrafish a powerful model system for clarifying mechanisms in toxicity. In contrast to the highly advanced knowledge base on molecular developmental genetics in zebrafish, our database regarding infectious and noninfectious diseases and pathologic lesions in zebrafish lags far behind the information available on most other domestic mammalian and avian species, particularly rodents. Currently, minimal data are available regarding spontaneous neoplasm rates or spontaneous aging lesions in any of the commonly used wild-type or mutant lines of zebrafish. Therefore, to fully utilize the potential of zebrafish as an animal model for understanding human development, disease, and toxicology we must greatly advance our knowledge on zebrafish diseases and pathology.
Collapse
Affiliation(s)
- Jan M Spitsbergen
- Department of Environmental and Molecular Toxicology and Marine/Freshwater Biomedical Sciences Center, Oregon State University, Corvallis, Oregon 97333, USA.
| | | |
Collapse
|
62
|
Abstract
Liver and pancreas initially develop by budding from the embryonic endoderm. The formation of these organs coincides with the appearance of endothelial cells (ECs) adjacent to the endoderm. ECs either develop in situ in organs, or are recruited by organs and are induced to form blood vessels. Recent reports on liver and pancreas have now shown that ECs also induce essential steps in organ formation such as morphogenesis and cell differentiation. This review summarizes reports on EC signaling during organogenesis and cell differentiation.
Collapse
Affiliation(s)
- Eckhard Lammert
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.
| | | | | |
Collapse
|
63
|
Liu S, Lu W, Obara T, Kuida S, Lehoczky J, Dewar K, Drummond IA, Beier DR. A defect in a novel Nek-family kinase causes cystic kidney disease in the mouse and in zebrafish. Development 2002; 129:5839-46. [PMID: 12421721 DOI: 10.1242/dev.00173] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The murine autosomal recessive juvenile cystic kidney (jck) mutation results in polycystic kidney disease. We have identified in jck mice a mutation in Nek8, a novel and highly conserved member of the Nek kinase family. In vitro expression of mutated Nek8 results in enlarged, multinucleated cells with an abnormal actin cytoskeleton. To confirm that a defect in the Nek8 gene can cause cystic disease, we performed a cross-species analysis: injection of zebrafish embryos with a morpholino anti-sense oligonucleotide corresponding to the ortholog of Nek8 resulted in the formation of pronephric cysts. These results demonstrate that comparative analysis of gene function in different model systems represents a powerful means to annotate gene function.
Collapse
Affiliation(s)
- Shanming Liu
- Genetics Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | | | | | | | | | | | | | | |
Collapse
|
64
|
Abstract
Signaling between growing blood vessels and the tissues that they innervate has traditionally been viewed as a one-way conversation, with organs and tissues supplying important cues for the growth and anatomical patterning of the blood vessels supplying them, but not vice-versa. Two recent papers now provide evidence that blood vessels can have an important role in promoting the assembly of organs and tissues. These papers show that proper formation of the pancreas and liver and induction of endocrine and hepatic cell types in these endodermal organs requires inductive signals from blood vessels.
Collapse
Affiliation(s)
- Brant Weinstein
- Unit of Vertebrate Organogenesis, Laboratory of Molecular Genetics, NICHD, NIH Building 6B, Room 309, 6 Center Drive, Bethesda, MD 20892, USA.
| |
Collapse
|
65
|
Morello R, Lee B. Insight into podocyte differentiation from the study of human genetic disease: nail-patella syndrome and transcriptional regulation in podocytes. Pediatr Res 2002; 51:551-8. [PMID: 11978876 DOI: 10.1203/00006450-200205000-00002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In recent years, our understanding of the molecular basis of kidney development has benefited from the study of rare genetic diseases affecting renal function. This has especially been the case with the differentiation of the highly specialized podocyte in the pathogenesis of human disorders and mouse phenotypes affecting the renal filtration barrier. This filtration barrier represents the end product of a complex series of signaling events that produce a tripartite structure consisting of interdigitating podocyte foot processes with intervening slit diaphragms, the glomerular basement membrane, and the fenestrated endothelial cell. Dysregulation of unique cytoskeletal and extracellular matrix proteins in genetic forms of nephrotic syndrome has shown how specific structural proteins contribute to podocyte function and differentiation. However, much less is known about the transcriptional determinants that both specify and maintain this differentiated cell. Our studies of a skeletal malformation syndrome, nail-patella syndrome, have shown how the LIM homeodomain transcription factor, Lmx1b, contributes to transcriptional regulation of glomerular basement membrane collagen expression by podocytes. Moreover, they raise intriguing questions about more global transcriptional regulation of podocyte morphogenesis.
Collapse
Affiliation(s)
- Roy Morello
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | | |
Collapse
|
66
|
Serluca FC, Drummond IA, Fishman MC. Endothelial signaling in kidney morphogenesis: a role for hemodynamic forces. Curr Biol 2002; 12:492-7. [PMID: 11909536 DOI: 10.1016/s0960-9822(02)00694-2] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The local presence of endothelial cells seems necessary for proper embryonic development of several organs. However, the signals involved are unknown. The glomerulus is generated by the coalescence of podocytes around an ingrowing capillary and is the site of blood ultrafiltration. In the absence of vessels, glomerular assembly does not occur. We describe mutations in the zebrafish that prevent glomerulogenesis. All mutants display cardiac dysfunction. Pharmacological interference with cardiac output and focal laser occlusion of the vessel similarly prevent glomerular formation. The unifying feature of all these perturbations is absence of blood flow. We find that expression of matrix metalloproteinase-2 (MMP-2), known in other systems to be regulated in a stretch-responsive manner, is in renal endothelial cells and is regulated by flow, suggesting that an MMP-2-sensitive event may be downstream of the flow-related signal. In support of this, blockade of MMP-2 activity by injection of TIMP-2 does not perturb circulation but does prevent glomerular assembly. Thus, vascular flow is required for glomerular assembly, most probably acting via a stretch-responsive signaling system in the vessel wall.
Collapse
Affiliation(s)
- Fabrizio C Serluca
- Cardiovascular Research Center and Developmental Biology Laboratory, Boston, MA 02119, USA
| | | | | |
Collapse
|
67
|
Abstract
This brief review summarizes features of the zebrafish, Danio rerio, that make it a suitable model organism for studies of regulatory physiology. The review presents the argument that random mutagenesis screens are a valuable gene-finding strategy to identify genes of functional importance and that their utility, although well established for developmental issues, will extend to a variety of topics of interest to the regulatory physiologist. Particular attention is drawn to the range of functional responses amenable to mutagenesis screens in larval zebrafish. Other virtues of the organism, the range of genomic tools, the potential for innovative optical methods, and the tractability for genetic and other experimental manipulations, are also described. Finally, the review provides examples of functional studies in zebrafish, including studies in sensory neurons, cardiac rhythm disturbances, gastrointestinal function, and studies of the developing kidney, that illustrate potential applications. Because of the relative ease with which combinatorial studies can be performed, the zebrafish may eventually be particularly valuable in understanding the functional interaction between subtle gene defects that cause polygenic disorders.
Collapse
Affiliation(s)
- Josephine P Briggs
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-2560, USA.
| |
Collapse
|
68
|
Abstract
Endothelial cells in blood vessels are known to be important during the later stages of organ development in the embryo. However, their involvement at the induction stage of organ formation has not been previously documented. As Bahary and Zon explain in their Perspective, new work demonstrates that endothelial cells secrete factors early in development that induce embryonic endoderm to become liver or pancreas (Matsumoto et al., Lammert et al.).
Collapse
Affiliation(s)
- N Bahary
- Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | | |
Collapse
|
69
|
Liang D, Chang JR, Chin AJ, Smith A, Kelly C, Weinberg ES, Ge R. The role of vascular endothelial growth factor (VEGF) in vasculogenesis, angiogenesis, and hematopoiesis in zebrafish development. Mech Dev 2001; 108:29-43. [PMID: 11578859 DOI: 10.1016/s0925-4773(01)00468-3] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Vascular endothelial growth factor (VEGF, VEGF-A), a selective mitogen for endothelial cells is a critical factor for vascular development. Two isoforms that differ in the presence of exons 6 and 7, Vegf(165) and Vegf(121), are the dominant forms expressed in zebrafish embryo. Simultaneous overexpression of both isoforms in the embryo results in increased production of flk1, tie1, scl, and gata1 transcripts, indicating a stimulation of both endothelial and hematopoietic lineages. We also demonstrate that vegf can stimulate hematopoiesis in zebrafish by promoting the formation of terminally differentiated red blood cells. Simultaneous overexpression of both isoforms also causes ectopic vasculature and blood cells in many of the injected embryos as well as pericardial edema in later stage embryos. Overexpression of vegf also resulted in earlier onset of flk1, tie1, scl, and gata1 expression in the embryo, indicating a possible role of vegf in stimulating the differentiation of both vascular and hematopoietic lineages. Co-injection of RNAs for both isoforms results in increased expression of three of these markers over and above that observed when either RNA is singly injected and analysis of vegf expression in the notochord mutants no tail and floating head suggests that the notochord patterns the formation of the dorsal aorta by stimulating adjacent somite cells to express vegf, which in turn functions as a signal in dorsal aorta patterning. Finally, studies of vegf expression in cloche mutant indicate that vegf expression is generally independent of cloche function. These results show that in the zebrafish embryo, vegf can not only stimulate endothelial cell differentiation but also hematopoiesis. Moreover, these effects are most dramatic when both vegf isoforms are co-expressed, indicating a synergistic effect of the expression of the two forms of the VEGF protein.
Collapse
Affiliation(s)
- D Liang
- Department of Biological Sciences, National University of Singapore, Singapore 119260
| | | | | | | | | | | | | |
Collapse
|
70
|
Davidson G, Dono R, Zeller R. FGF signalling is required for differentiation-induced cytoskeletal reorganisation and formation of actin-based processes by podocytes. J Cell Sci 2001; 114:3359-66. [PMID: 11591823 DOI: 10.1242/jcs.114.18.3359] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To examine the potential role of fibroblast growth factor (FGF) signalling during cell differentiation, we used conditionally immortalised podocyte cells isolated from kidneys of Fgf2 mutant and wild-type mice. Wild-type mouse podocyte cells upregulate FGF2 expression when differentiating in culture, as do maturing podocytes in vivo. Differentiating wild-type mouse podocyte cells undergo an epithelial to mesenchymal-like transition, reorganise their actin cytoskeleton and extend actin-based cellular processes; all of these activities are similar to the activity of podocytes in vivo. Molecular analysis of Fgf2 mutant mouse podocyte cells reveals a general disruption of FGF signalling as expression of Fgf7 and Fgf10 are also downregulated. These FGF mutant mouse podocyte cells in culture fail to activate mesenchymal markers and their post-mitotic differentiation is blocked. Furthermore, mutant mouse podocyte cells in culture fail to reorganise their actin cytoskeleton and form actin-based cellular processes. These studies show that FGF signalling is required by cultured podocytes to undergo the epithelial to mesenchymal-like changes necessary for terminal differentiation. Together with other studies, these results point to a general role for FGF signalling in regulating cell differentiation and formation of actin-based cellular processes during morphogenesis.
Collapse
Affiliation(s)
- G Davidson
- EMBL, Meyerhofstrasse1, D-69117 Heidelberg, Germany
| | | | | |
Collapse
|
71
|
Rottbauer W, Baker K, Wo ZG, Mohideen MA, Cantiello HF, Fishman MC. Growth and function of the embryonic heart depend upon the cardiac-specific L-type calcium channel alpha1 subunit. Dev Cell 2001; 1:265-75. [PMID: 11702785 DOI: 10.1016/s1534-5807(01)00023-5] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The heart must function from the moment of its embryonic assembly, but the molecular underpinnings of the first heart beat are not known, nor whether function determines form at this early stage. Here, we find by positional cloning that the embryonic lethal island beat (isl) mutation in zebrafish disrupts the alpha1 C L-type calcium channel subunit (C-LTCC). The isl atrium is relatively normal in size, and individual cells contract chaotically, in a pattern resembling atrial fibrillation. The ventricle is completely silent. Unlike another mutation with a silent ventricle, isl fails to acquire the normal number of myocytes. Thus, calcium signaling via C-LTCC can regulate heart growth independently of contraction, and plays distinctive roles in fashioning both form and function of the two developing chambers.
Collapse
Affiliation(s)
- W Rottbauer
- Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | | | | | | | | | | |
Collapse
|
72
|
Abstract
Vertebrate embryos use a series of transient kidneys to regulate fluid balance, osmolarity and metabolic waste during development. The first kidney to form in the embryo is the pronephros. This kidney is composed of several cell types with very different functions and is organized into discrete segments: glomerulus, tubules and nephric duct. The site of origin of these cells is poorly understood, as are their lineage relationships. We have defined regions of the intermediate mesoderm as candidates for the pronephric field by expression patterns of the Wilms’ Tumor suppressor gene (wt1), single-minded 1 (sim1) and pax2.1. All of these potential kidney markers are expressed in a stripe of intermediate mesoderm, with distinct, overlapping antero-posterior borders. We labeled small groups of cells in this area by laser uncaging of a fluorescent dextran, and then tracked their fates. We found that there was a bounded contiguous region of the intermediate mesoderm that provides pronephric progenitors. As is true for other organ fields, the pronephric field regulates after focal destruction, such that a normal pronephros forms after laser-mediated removal of the wt1 domain. The progenitors for podocytes, tubular cells and duct are restricted to subdomains within the pronephric field. The most anterior cells in the pronephric field give rise to podocytes. This corresponds to the wt1-expressing region. The next more posterior cells contribute to the tubule, and express both wt1 and pax2.1. The most posterior cells contribute to the nephric duct, and these express pax2.1 and sim1, but not wt1. Thus, there is a field for the pronephric kidney with classical attributes of defined border, pre-pattern and regulation. The pattern of the fate map reflects particular combinations of transcription factors.
Collapse
Affiliation(s)
- F C Serluca
- Cardiovascular Research Center and Developmental Biology Laboratory, Massachusetts General Hospital and Department of Medicine, Harvard Medical School, Boston, MA 02129, USA
| | | |
Collapse
|
73
|
Abstract
For more than 40 years now, the developing kidney has served as a model paradigm for epithelial-mesenchymal interactions. The principles of inductive signaling, epithelial cell differentiation, and pattern formation are now being addressed with modern genetic and biochemical tools. In addition to the mammalian kidney organ culture model, both zebrafish and Xenopus laevis demonstrate great potential for investigating the molecular mechanisms of kidney organogenesis within a whole organism. In this review, the papers presented in this special issue are discussed with respect to recent progress in the renal development field. Coincidentally, it has become increasingly clear that progress made in renal development can impact our understanding of the genetic basis of disease.
Collapse
Affiliation(s)
- G R Dressler
- Department of Pathology, University of Michigan, Ann Arbor 48109, USA.
| |
Collapse
|
74
|
Majumdar A, Drummond IA. The zebrafish floating head mutant demonstrates podocytes play an important role in directing glomerular differentiation. Dev Biol 2000; 222:147-57. [PMID: 10885753 DOI: 10.1006/dbio.2000.9642] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In zebrafish, the pronephric glomerulus occupies a midline position underneath the notochord and is vascularized through angiogenic capillary ingrowth from the dorsal aorta. The midline mutants floating head (flh), sonic you (syu), and you-too (yot) provide the opportunity to study glomerular differentiation in the absence of the notochord and vascularization from the dorsal aorta. In flh, syu, and yot mutants, glomeruli differentiate at ectopic lateral positions within the embryo and contain morphologically identifiable podocyte and endothelial cell types. In the absence of the dorsal aorta, endothelia from an alternate source are recruited by podocytes during glomerular vascularization to make functional glomeruli. Our results suggest that midline signals are required for proper glomerular morphogenesis but not for the differentiation of podocytes. Podocytes appear to play an important role in directing cellular recruitment events leading to glomerular differentiation. Furthermore, we find defects in sclerotomal development that correlate with defects in glomerular morphogenesis suggesting a possible link between the formation of these embryonic structures.
Collapse
Affiliation(s)
- A Majumdar
- Renal Unit, Massachusetts General Hospital, Charlestown 02129, USA
| | | |
Collapse
|
75
|
Majumdar A, Lun K, Brand M, Drummond IA. Zebrafish no isthmus reveals a role for pax2.1 in tubule differentiation and patterning events in the pronephric primordia. Development 2000; 127:2089-98. [PMID: 10769233 DOI: 10.1242/dev.127.10.2089] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pax genes are important developmental regulators and function at multiple stages of vertebrate kidney organogenesis. In this report, we have used the zebrafish pax2.1 mutant no isthmus to investigate the role for pax2.1 in development of the pronephros. We demonstrate a requirement for pax2.1 in multiple aspects of pronephric development including tubule and duct epithelial differentiation and cloaca morphogenesis. Morphological analysis demonstrates that noi(−)larvae specifically lack pronephric tubules while glomerular cell differentiation is unaffected. In addition, pax2.1 expression in the lateral cells of the pronephric primordium is required to restrict the domains of Wilms' tumor suppressor (wt1) and vascular endothelial growth factor (VEGF) gene expression to medial podocyte progenitors. Ectopic podocyte-specific marker expression in pronephric duct cells correlates with loss of expression of the pronephric tubule and duct-specific markers mAb 3G8 and a Na(+)/K(+) ATPase (α)1 subunit. The results suggest that the failure in pronephric tubule differentiation in noi arises from a patterning defect during differentiation of the pronephric primordium and that mutually inhibitory regulatory interactions play an important role in defining the boundary between glomerular and tubule progenitors in the forming nephron.
Collapse
Affiliation(s)
- A Majumdar
- Renal Unit, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | | | | | | |
Collapse
|
76
|
Abstract
Branching morphogenesis, mesenchymal cell condensation and mesenchymal-to-epithelial conversion are key steps in kidney development and morphogenesis of several other organs. Review articles describing our current knowledge of the genetic and molecular regulation of these processes have been published. Therefore, this review focuses on the important question of cell lineage specification during kidney development. We describe how new insights are being made into the specification of kidney cells in the intermediate mesoderm, as well as specification of cells that will form the renal mesenchyme, ureteric duct, nephron tubule epithelium and renal vasculature.
Collapse
Affiliation(s)
- A T Clark
- Department of Pathology, Baylor College of Medicine, Houston, Texas, USA
| | | |
Collapse
|
77
|
Miner JH, Li C. Defective glomerulogenesis in the absence of laminin alpha5 demonstrates a developmental role for the kidney glomerular basement membrane. Dev Biol 2000; 217:278-89. [PMID: 10625553 DOI: 10.1006/dbio.1999.9546] [Citation(s) in RCA: 226] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Laminins are major components of all basement membranes. They are a diverse group of alpha/beta/gamma heterotrimers formed from five alpha, three beta, and three gamma chains. Laminin alpha5 is a widely expressed chain found in many embryonic and adult basement membranes. During embryogenesis, alpha5 has a role in disparate developmental processes, including neural tube closure, digit septation, and placentation. Here, we analyzed kidney development in Lama5 mutant embryos and found a striking defect in glomerulogenesis associated with an abnormal glomerular basement membrane (GBM). This correlates with failure of the developmental switch in laminin alpha chain deposition in which alpha5 replaces alpha1 in the GBM at the capillary loop stage of glomerulogenesis. In the absence of a normal GBM, glomerular epithelial cells were in disarray, and endothelial and mesangial cells were extruded from within the constricting glomerulus, leading to a complete absence of vascularized glomeruli. In addition, a minority of Lama5 mutant mice lacked one or both kidneys, indicating that laminin alpha5 is also important in earlier kidney development. Our results demonstrate a dual role for laminin alpha5 in kidney development, illustrate a novel defect in glomerulogenesis, and indicate a heretofore unappreciated developmental role for the GBM in influencing the behavior of epithelial and endothelial cells.
Collapse
Affiliation(s)
- J H Miner
- Renal Division, Department of Internal Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | | |
Collapse
|