301
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Kelly M, Chen P. Shaping the mammalian auditory sensory organ by the planar cell polarity pathway. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2007; 51:535-47. [PMID: 17891715 PMCID: PMC4158833 DOI: 10.1387/ijdb.072344mk] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The human ear is capable of processing sound with a remarkable resolution over a wide range of intensity and frequency. This ability depends largely on the extraordinary feats of the hearing organ, the organ of Corti and its sensory hair cells. The organ of Corti consists of precisely patterned rows of sensory hair cells and supporting cells along the length of the snail-shaped cochlear duct. On the apical surface of each hair cell, several rows of actin-containing protrusions, known as stereocilia, form a "V"-shaped staircase. The vertices of all the "V"-shaped stereocilia point away from the center of the cochlea. The uniform orientation of stereocilia in the organ of Corti manifests a distinctive form of polarity known as planar cell polarity (PCP). Functionally, the direction of stereociliary bundle deflection controls the mechanical channels located in the stereocilia for auditory transduction. In addition, hair cells are tonotopically organized along the length of the cochlea. Thus, the uniform orientation of stereociliary bundles along the length of the cochlea is critical for effective mechanotransduction and for frequency selection. Here we summarize the morphological and molecular events that bestow the structural characteristics of the mammalian hearing organ, the growth of the snail-shaped cochlear duct and the establishment of PCP in the organ of Corti. The PCP of the sensory organs in the vestibule of the inner ear will also be described briefly.
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Affiliation(s)
- Michael Kelly
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Ping Chen
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
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302
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Zhang Y, Yeh JR, Mara A, Ju R, Hines JF, Cirone P, Griesbach HL, Schneider I, Slusarski DC, Holley SA, Crews CM. A chemical and genetic approach to the mode of action of fumagillin. ACTA ACUST UNITED AC 2006; 13:1001-9. [PMID: 16984890 PMCID: PMC2583369 DOI: 10.1016/j.chembiol.2006.07.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/26/2006] [Accepted: 07/17/2006] [Indexed: 01/24/2023]
Abstract
Previous mode of action studies identified methionine aminopeptidase 2 (MetAP-2) as the target of the antiangiogenic natural product fumagillin and its drug candidate analog, TNP-470. We report here that TNP-470-mediated MetAP-2 inhibition blocks noncanonical Wnt signaling, which plays a critical role in development, cell differentiation, and tumorigenesis. Consistent with this finding, antisense MetAP-2 morpholino oligonucleotide injection in zebrafish embryos phenocopies gastrulation defects seen in noncanonical Wnt5 loss-of-function zebrafish mutants. MetAP-2 inhibition or depletion blocks signaling downstream of the Wnt receptor Frizzled, but upstream of Calmodulin-dependent Kinase II, RhoA, and c-Jun N-terminal Kinase. Moreover, we demonstrate that TNP-470 does not block the canonical Wnt/beta-catenin pathway. Thus, TNP-470 selectively regulates noncanonical over canonical Wnt signaling and provides a unique means to explore and dissect the biological systems mediated by these pathways.
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Affiliation(s)
- Yi Zhang
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Jing Ruey Yeh
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Andrew Mara
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Rong Ju
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - John F. Hines
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Pasquale Cirone
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Hilary L. Griesbach
- Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
| | - Igor Schneider
- Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
| | - Diane C. Slusarski
- Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
| | - Scott A. Holley
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Craig M. Crews
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520
- Department of Chemistry, Yale University, New Haven, Connecticut 06520
- Department of Pharmacology, Yale University, New Haven, Connecticut 06520
- Correspondence:
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303
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Wada H, Tanaka H, Nakayama S, Iwasaki M, Okamoto H. Frizzled3a and Celsr2 function in the neuroepithelium to regulate migration of facial motor neurons in the developing zebrafish hindbrain. Development 2006; 133:4749-59. [PMID: 17079269 DOI: 10.1242/dev.02665] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Migration of neurons from their birthplace to their final target area is a crucial step in brain development. Here, we show that expression of the off-limits/frizzled3a (olt/fz3a) and off-road/celsr2 (ord/celsr2) genes in neuroepithelial cells maintains the facial (nVII) motor neurons near the pial surface during their caudal migration in the zebrafish hindbrain. In the absence of olt/fz3a expression in the neuroepithelium, nVII motor neurons extended aberrant radial processes towards the ventricular surface and mismigrated radially to the dorsomedial part of the hindbrain. Our findings reveal a novel role for these genes, distinctive from their already known functions, in the regulation of the planar cell polarity (i.e. preventing integration of differentiated neurons into the neuroepithelial layer). This contrasts markedly with their reported role in reintegration of neuroepithelial daughter cells into the neuroepithelial layer after cell division.
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Affiliation(s)
- Hironori Wada
- Laboratory for Developmental Gene Regulation, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN Saitama 351-0198, Japan
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304
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Jopling C, Hertog JD. Essential role for Csk upstream of Fyn and Yes in zebrafish gastrulation. Mech Dev 2006; 124:129-36. [PMID: 17157484 DOI: 10.1016/j.mod.2006.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 10/12/2006] [Accepted: 10/21/2006] [Indexed: 11/25/2022]
Abstract
Morphogenetic cell movements during gastrulation shape the vertebrate embryo bodyplan. Non-canonical Wnt signaling has been established to regulate convergence and extension cell movements that mediate anterior-posterior axis elongation. In recent years, many other factors have been implicated in the process by modulation of non-canonical Wnt signaling or by different, unknown mechanisms. We have found that the Src family kinases, Fyn and Yes, are required for normal convergence and extension cell movements in zebrafish embryonic development and they signal in parallel to non-canonical Wnts, eventually converging on a common downstream factor, RhoA. Here, we report that Csk, a negative regulator of Src family kinases has a role in gastrulation cell movements as well. Csk knock down induced a phenotype that was similar to the defects observed after knock down of Fyn and Yes, in that gastrulation cell movements were impaired, without affecting cell fate. The Csk knock down phenotype was rescued by simultaneous partial knock down of Fyn and Yes. We conclude that Csk acts upstream of Fyn and Yes to control vertebrate gastrulation cell movements.
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Affiliation(s)
- Chris Jopling
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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305
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Tadjuidje E, Hollemann T. Cholesterol homeostasis in development: the role of Xenopus 7-dehydrocholesterol reductase (Xdhcr7) in neural development. Dev Dyn 2006; 235:2095-110. [PMID: 16752377 DOI: 10.1002/dvdy.20860] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
7-dehydrocholesterol reductase (7-Dhcr) catalyses the final step in the pathway of cholesterol biosynthesis. Human patients with inborn errors of 7-Dhcr (Smith-Lemli-Opitz-Syndrome) have elevated serum levels of 7-dehydrocholesterol but low levels of cholesterol, which in phenotypical terms can result in growth retardation, craniofacial abnormalities including cleft palate, and reduced metal abilities. This study reports the isolation and molecular characterisation of 7-dehydrocholesterol reductase (Xdhcr7) from Xenopus laevis. During early embryonic development, the expression of Xdhcr7 is first of all spatially restricted to the Spemann's organizer and later to the notochord. In both tissues, Xdhcr7 is coexpressed with Sonic hedgehog (Shh), which itself is cholesterol-modified during autoproteolytic cleavage. Data from Xdhcr7 overexpression and knockdown experiments reveals that a tight control of cholesterol synthesis is particularly important for proper development of the central and peripheral nervous system.
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Affiliation(s)
- Emmanuel Tadjuidje
- University of Halle-Wittenberg, Institut für Physiologische Chemie, Halle/Saale, Germany
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306
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Hong E, Brewster R. N-cadherin is required for the polarized cell behaviors that drive neurulation in the zebrafish. Development 2006; 133:3895-905. [PMID: 16943271 DOI: 10.1242/dev.02560] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Through the direct analysis of cell behaviors, we address the mechanisms underlying anterior neural tube morphogenesis in the zebrafish and the role of the cell adhesion molecule N-cadherin (N-cad) in this process. We demonstrate that although the mode of neurulation differs at the morphological level between amphibians and teleosts, the underlying cellular mechanisms are conserved. Contrary to previous reports, the zebrafish neural plate is a multi-layered structure, composed of deep and superficial cells that converge medially while undergoing radial intercalation, to form a single cell-layered neural tube. Time-lapse recording of individual cell behaviors reveals that cells are polarized along the mediolateral axis and exhibit protrusive activity. In N-cad mutants, both convergence and intercalation are blocked. Moreover, although N-cad-depleted cells are not defective in their ability to form protrusions, they are unable to maintain them stably. Taken together, these studies uncover key cellular mechanisms underlying neural tube morphogenesis in teleosts, and reveal a role for cadherins in promoting the polarized cell behaviors that underlie cellular rearrangements and shape the vertebrate embryo.
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Affiliation(s)
- Elim Hong
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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307
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Abstract
Polycystic kidneys are caused by an amazingly broad array of genetic mutations and manipulations. The ciliary hypothesis has evolved as the unifying concept of cystogenesis: cilia, bend by fluid flow, initiate a calcium influx that prevents cyst formation. The integrity of ciliary functions has been linked to the polycystic kidney disease gene products localizing to the cilium or the basal body/centrosome. Until recently, the signals and cellular programs located downstream of the ciliary-mediated calcium flux have remained elusive. Now, several reports point towards a role of the cilium or the basal body/centrosome complex in planar cell polarity, a pathway that orients cell in the plane of a tissue layer. First, Inversin, a protein mutated in nephronophthisis type II was found to act as a switch between the canonical and the noncanonical Wnt cascade, suggesting that beta-catenin/TCF-dependent gene transcription has to be curtailed to allow normal tubular differentiation. Second, heterozygote deletions of Bardet-Biedl syndrome proteins affect neural tube closure and disrupt the cochlear sterociliary bundles, two typical planar cell polarity defects. Third, tubular epithelial cells undergo oriented cell division during tubular elongation, along the axis of the anterior-posterior axis of the nephron. Thus, the cilium or the basal body/centrosome complex may provide the spatial cues to position the centrosome and the mitotic spindle before the next cell division. Failure to communicate this spatial information may condemn the tubular epithelial cells to proliferate and to form cysts.
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Affiliation(s)
- M Simons
- Renal Division, University Hospital Freiburg, Freiburg, Germany.
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308
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De Marco P, Merello E, Mascelli S, Capra V. Current perspectives on the genetic causes of neural tube defects. Neurogenetics 2006; 7:201-21. [PMID: 16941185 DOI: 10.1007/s10048-006-0052-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 05/29/2006] [Indexed: 10/24/2022]
Abstract
Neural tube defects (NTDs) are a group of severe congenital abnormalities resulting from the failure of neurulation. The pattern of inheritance of these complex defects is multifactorial, making it difficult to identify the underlying causes. Scientific research has rapidly progressed in experimental embryology and molecular genetics to elucidate the basis of neurulation. Crucial mechanisms of neurulation include the planar cell polarity pathway, which is essential for the initiation of neural tube closure, and the sonic hedgehog signaling pathway, which regulates neural plate bending. Genes influencing neurulation have been investigated for their contribution to human neural tube defects, but only genes with well-established role in convergent extension provide an exciting new set of candidate genes. Biochemical factors such as folic acid appear to be the greatest modifiers of NTDs risk in the human population. Consequently, much research has focused on genes of folate-related metabolic pathways. Variants of several such genes have been found to be significantly associated with the risk of neural tube defects in more studies. In this manuscript, we reviewed the current perspectives on the causes of neural tube defects and highlighted that we are still a long way from understanding the etiology of these complex defects.
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Affiliation(s)
- Patrizia De Marco
- U.O. Neurochirurgia, Istituto G. Gaslini, Largo G. Gaslini 5, 16148, Genova, Italy
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309
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Abstract
The process of "convergence and extension" regulates cellular intercalation during gastrulation. An ArfGAP-PAR protein complex is required for the associated cellular polarization. Potential interactions between this complex and relevant planar cell polarity factors in this context are discussed.
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Affiliation(s)
- Marek Mlodzik
- Brookdale Department of Molecular, Cell & Developmental Biology, Mt. Sinai School of Medicine, Annenberg Building 18-92, One Gustave L. Levy Place, New York, New York 10029, USA
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310
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Pugacheva EN, Roegiers F, Golemis EA. Interdependence of cell attachment and cell cycle signaling. Curr Opin Cell Biol 2006; 18:507-15. [PMID: 16919436 PMCID: PMC2531247 DOI: 10.1016/j.ceb.2006.08.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Accepted: 08/03/2006] [Indexed: 01/01/2023]
Abstract
Adult metazoans represent the culmination of an intricate developmental process involving the temporally and spatially orchestrated division, migration, differentiation, attachment, polarization and death of individual cells. An elaborate infrastructure connecting the cell cycle and cell attachment machinery is essential for such exquisite integration of developmental processes. Integrin-, cadherin-, Merlin- and planar cell polarity (PCP)-dependent signaling cascades quantitatively and qualitatively program cell division during development. Proteins in this signaling infrastructure may represent an important source of cancer vulnerability in metazoans, as their dysfunction can pleiotropically promote the oncogenic process.
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Affiliation(s)
- Elena N Pugacheva
- Division of Basic Science, Fox Chase Cancer Center, 333 Cottman Ave. Philadelphia, PA 19111, USA
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311
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Nechiporuk T, Vasioukhin V. Planar Cell Polarity Planes the Inconveniences of Cell Division into a Smooth Morphogenetic Process. Dev Cell 2006; 10:153-4. [PMID: 16459292 DOI: 10.1016/j.devcel.2006.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Cell divisions are necessary, but also very disruptive for morphogenesis. Dividing cells lose many intercellular contacts and polarized features. This breaks the magnificent topology of the developing embryo and, if left unrepaired, can lead to severe tissue disorganization. A recent study demonstrated that cells use the planar cell polarity pathway to reestablish polarity and reintegrate daughter cells into developing tissue.
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Affiliation(s)
- Tamilla Nechiporuk
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
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