201
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Kopan R, Schroeter EH, Weintraub H, Nye JS. Signal transduction by activated mNotch: importance of proteolytic processing and its regulation by the extracellular domain. Proc Natl Acad Sci U S A 1996; 93:1683-8. [PMID: 8643690 PMCID: PMC40002 DOI: 10.1073/pnas.93.4.1683] [Citation(s) in RCA: 410] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Previous studies imply that the intracellular domain of Notch1 must translocate to the nucleus for its activity. In this study, we demonstrate that a mNotch1 mutant protein that lacks its extracellular domain but retains its membrane-spanning region becomes proteolytically processed on its intracellular surface and, as a result, the activated intracellular domain (mNotchIC) is released and can move to the nucleus. Proteolytic cleavage at an intracellular site is blocked by protease inhibitors. Intracellular cleavage is not seen in cells transfected with an inactive variant, which includes the extracellular lin-Notch-glp repeats. Collectively, the studies presented here support the model that mNotch1 is proteolytically processed and the cleavage product is translocated to the nucleus for mNotch1 signal transduction.
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Affiliation(s)
- R Kopan
- Division of Dermatology, Department of Molecular Biology and Pharmacology, Washington University, St. Louis, MO 63110, USA
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202
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Hoskins R, Hajnal AF, Harp SA, Kim SK. The C. elegans vulval induction gene lin-2 encodes a member of the MAGUK family of cell junction proteins. Development 1996; 122:97-111. [PMID: 8565857 DOI: 10.1242/dev.122.1.97] [Citation(s) in RCA: 157] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The lin-2 gene is required for the induction of the Caenorhabditis elegans vulva. Vulval development is initiated by a signal from the anchor cell that is transduced by a receptor tyrosine kinase/Ras pathway. We show that lin-2 acts in the vulval precursor cell P6.p, downstream of lin-3 EGF and upstream of let-60 ras, to allow expression of the 1 degrees cell fate. lin-2 encodes a protein of relative molecular mass 109,000 (LIN-2A) with regions of similarity to CaM kinase II and membrane-associated guanylate kinases. Mutant lin-2 transgenes designed to lack either protein kinase or guanylate kinase activity are functional, indicating that LIN-2A has a structural rather than an enzymatic role in vulval induction. Most or all identified membrane-associated guanylate kinases are components of cell junctions, including vertebrate tight junctions and arthropod septate junctions in epithelia. Thus, LIN-2A may be a component of the cell junctions of the epithelial vulval precursor cells that is required for signaling by the receptor tyrosine kinase LET-23. We propose that LIN-2A is required for the localization of one or more signal transduction proteins (such as LET-23) to either the basal membrane domain or the cell junctions, and that mislocalization of signal transduction proteins in lin-2 mutants interferes with vulval induction.
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Affiliation(s)
- R Hoskins
- Department of Developmental Biology, Stanford University Medical School, CA 94305, USA
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203
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The wingless/Wnt-1 Signaling Pathway—New Insights into the Cellular Mechanisms of Signal Transduction. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1064-2722(08)60056-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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204
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Schweisguth F, Gho M, Lecourtois M. Control of cell fate choices by lateral signaling in the adult peripheral nervous system of Drosophila melanogaster. DEVELOPMENTAL GENETICS 1996; 18:28-39. [PMID: 8742832 DOI: 10.1002/(sici)1520-6408(1996)18:1<28::aid-dvg4>3.0.co;2-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The thoracic integument of the adult fruit fly is a relatively simple but highly patterned structure. It is composed of sensory organ cells distributed within a monolayer of epidermal cells. Both cell types are easily detected at the cuticular surface, as each external sense organ forms a sensory bristle and each epidermal cell secretes a small nonsensory hair. Inhibitory cell-cell interactions play a key role in regulating the distribution as well as the formation of the sense organs. This review focuses on the role of these cell-cell interactions in the adoption of alternative cell fates. We also show that Notch, Hairless, and Suppressor of Hairless, three components of this intercellular signaling pathway, exhibit dose-dependent genetic interactions. Finally we address how this intercellular signaling mechanism may be modulated to result in highly reproducible outcomes.
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Affiliation(s)
- F Schweisguth
- Institute Jacques Monod, University of Paris, France
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205
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Rulifson EJ, Blair SS. Notch regulates wingless expression and is not required for reception of the paracrine wingless signal during wing margin neurogenesis in Drosophila. Development 1995; 121:2813-24. [PMID: 7555709 DOI: 10.1242/dev.121.9.2813] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the developing wing margin of Drosophila, wingless is normally expressed in a narrow stripe of cells adjacent to the proneural cells that form the sensory bristles of the margin. Previous work has shown that this wingless is required for the expression of the proneural achaete-scute complex genes and the subsequent formation of the sensory bristles along the margin; recently, it has been proposed that the proneural cells require the Notch protein to properly receive the wingless signal. We have used clonal analysis of a null allele of Notch to test this idea directly. We found that Notch was not required by prospective proneural margin cells for the expression of scute or the formation of sensory precursors, indicating Notch is not required for the reception of wingless signal. Loss of Notch from proneural cells produced cell-autonomous neurogenic phenotypes and precocious differentiation of sensory cells, as would be expected if Notch had a role in lateral inhibition within the proneural regions. However, loss of scute expression and of sensory precursors was observed if clones substantially included the normal region of wingless expression. These ‘anti-proneural’ phenotypes were associated with the loss of wingless expression; this loss may be partially or wholly responsible for the anti-proneural phenotype. Curiously, Notch- clones limited to the dorsal or ventral compartments could disrupt wingless expression and proneural development in the adjacent compartment. Analysis using the temperature-sensitive Notch allele indicated that the role of Notch in the regulation of wingless expression precedes the requirement for lateral inhibition in proneural cells. Furthermore, overexpression of wingless with a heat shock-wingless construct rescued the loss of sensory precursors associated with the early loss of Notch.
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Affiliation(s)
- E J Rulifson
- Department of Zoology, University of Wisconsin, Madison 53706, USA
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206
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Ahmad I, Zaqouras P, Artavanis-Tsakonas S. Involvement of Notch-1 in mammalian retinal neurogenesis: association of Notch-1 activity with both immature and terminally differentiated cells. Mech Dev 1995; 53:73-85. [PMID: 8555113 DOI: 10.1016/0925-4773(95)00425-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Notch pathway is thought to define an evolutionarily conserved signaling mechanism that regulates the differentiation of immature cells through cells interactions. We have examined the expression of the Notch-1 receptor, the central element of this pathway, in the developing rat retina, where cell-fate choices depend upon a series of local cell interactions. Notch-1 immunoreactivity is associated with differentiating cells at different stages of retinal neurogenesis, suggesting that Notch-1 may play a role in the successive cell-fate determination which governs retinal development. In addition, the Notch-1 immunoreactivity is detected in nuclei of postmitotic, differentiated neurons of the adult retina. Our observations raise the possibility that besides its role in the differentiation of immature cell populations Notch-1 activity may also be involved in the maintenance of the differentiated state.
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Affiliation(s)
- I Ahmad
- Department of Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, 68198-6395, USA
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207
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Zagouras P, Stifani S, Blaumueller CM, Carcangiu ML, Artavanis-Tsakonas S. Alterations in Notch signaling in neoplastic lesions of the human cervix. Proc Natl Acad Sci U S A 1995; 92:6414-8. [PMID: 7604005 PMCID: PMC41528 DOI: 10.1073/pnas.92.14.6414] [Citation(s) in RCA: 297] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The development of cancer is a cellular process that reflects and is partly driven by alterations in cell determination. Mutations in various molecules responsible for cell determination have been identified as being oncogenic, but little is known about the involvement of normal cell fate-determining mechanisms in the oncogenic process. The Notch pathway defines an evolutionarily conserved, general cell interaction mechanism that controls fundamental aspects of cell determination during vertebrate and invertebrate development. We have explored the involvement of the human Notch pathway in human cervical tissues, which define a cellular environment where cell fate changes take place and where neoplastic conditions have been well characterized. Our evidence suggests that Notch expression is associated with cell populations that are undergoing cell fate changes and that Notch activity can be used to monitor cell fate abnormalities in cervical as well as other epithelial neoplasias.
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Affiliation(s)
- P Zagouras
- Department of Biology, Yale University, New Haven, CT 06536, USA
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208
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Rebay I, Rubin GM. Yan functions as a general inhibitor of differentiation and is negatively regulated by activation of the Ras1/MAPK pathway. Cell 1995; 81:857-66. [PMID: 7781063 DOI: 10.1016/0092-8674(95)90006-3] [Citation(s) in RCA: 295] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Drosophila yan has been postulated to act as an antagonist of the proneural signal mediated by the sevenless/Ras1/MAPK pathway. We have mutagenized the eight MAPK phosphorylation consensus sites of yan and examined the effects of overexpressing the mutant protein in transgenic flies and transfected S2 cultured cells. Our results suggest that phosphorylation by MAPK affects the stability and subcellular localization of yan, resulting in rapid down-regulation of yan activity. Furthermore, MAPK-mediated down-regulation of yan function appears to be critical for the proper differentiation of both neuronal and nonneuronal tissues throughout development, suggesting that yan is an essential component of a general timing mechanism controlling the competence of a cell to respond to inductive signals.
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Affiliation(s)
- I Rebay
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA
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209
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Abstract
The Notch/Lin-12/Glp-1 receptor family mediates the specification of numerous cell fates during development in Drosophila and Caenorhabditis elegans. Studies on the expression, mutant phenotypes, and developmental consequences of unregulated receptor activation have implicated these proteins in a general mechanism of local cell signaling, which includes interactions between equivalent cells and between different cell types. Genetic approaches in flies and worms have identified putative components of the signaling cascade, including a conserved family of extracellular ligands and two cellular factors that may associate with the Notch Intracellular domain. One factor, the Drosophila Suppressor of Hairless protein, is a DNA-binding protein, which suggests that Notch signaling may involve relatively direct signal transmission from the cell surface to the nucleus. Several vertebrate Notch receptors have also been discovered recently and play important roles in normal development and tumorigenesis.
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Affiliation(s)
- S Artavanis-Tsakonas
- Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University, New Haven, CT 06536, USA
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210
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Abstract
The neurogenic ectoderm of Drosophila melanogaster consists of the ventral neuroectoderm and the procephalic neuroectoderm. It is hypothesized that epidermal and central neural progenitor cells separate from each other in three steps: conference on the neuroectodermal cells the capability of producing neural or epidermal progenies, separation of the two classes of progenitor cells, and specification of particular types of neuroblasts and epidermoblasts. Separation of neuroblasts and epidermoblasts is controlled by proneural and neurogenic genes. Delta and Notch serve as mediators of direct protein-protein interactions. E(SPL)-C inhibits neurogenesis, creating epidermal cells. The achaete-scute complex (AS-C) controls the commitment of nonoverlapping populations of neuroblasts and leads the development of neuroectodermal cells as neuroblasts.
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211
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Miyamoto H, Nihonmatsu I, Kondo S, Ueda R, Togashi S, Hirata K, Ikegami Y, Yamamoto D. canoe encodes a novel protein containing a GLGF/DHR motif and functions with Notch and scabrous in common developmental pathways in Drosophila. Genes Dev 1995; 9:612-25. [PMID: 7698650 DOI: 10.1101/gad.9.5.612] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The canoemisty1 (cnomis1) mutation was isolated by virtue of its severe rough eye phenotype from approximately 500 fly lines, each harboring a single autosomal insertion of a P element (Bm delta w). Excision of the P element generated a lethal, null allele, cnomis10, together with many revertants with normal eye morphology. Ommatidia homozygous for cnomis10, produced in an otherwise wild-type eye by somatic recombination, typically contain a reduced number of outer photoreceptors. Some cnomis1 homozygous adults bear extra macrochaetes on the head, notum, humerus and/or scutellum. cnomis1 hemizygotes often show conspicuous wing phenotypes such as a notched blade and the loss of a cross vein. The sequence of cno cDNA clones isolated from an embryonic cDNA library revealed a long open reading frame that potentially encodes a 1893-amino-acid protein with the GLGF/DHR motif, a conserved sequence in Discs large, Dishevelled, and some other proteins associated with cellular junctions. Flies doubly mutant for cnomis1 and scabrous1 (sca1) and those for cnomis1 and the split (spl) allele of Notch (N) always have rumpled wings curved downward. The spl; cnomis1 double mutant flies also exhibit a "giant socket" phenotype. These phenotypes are rarely observed flies singly mutant for either cnomis1, sca1 or spl. The wing vein gaps caused by Abruptex1, a N allele producing an activated form of N protein, are dominantly suppressed by cnomis1. Heterozygosity for shaggy and myospheroid promotes formation of extra wing veins in cnomis1 homozygotes. The genetic interactions suggest that cno participates with members of the N pathway in regulating adhesive cell-cell interactions for the determination of cell fate.
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Affiliation(s)
- H Miyamoto
- Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan
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212
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Abstract
The neurogenic gene Xotch acts to divert cellular determination during gastrulation in Xenopus embryos. We examined the role of Xotch in the developing retina, where cell signaling events are thought to affect differentiation. Xotch is expressed in undifferentiated precursor cells of the ciliary marginal zone and late embryonic central retina. It is not expressed in stem cells or in differentiated neurons and glia. Expression in the retina is spatially restricted even in the absence of cell division. The final Xotch-positive precursor cells in the central retina mostly differentiate as Müller glia, suggesting that this is the last available fate of cells in the frog retina. Transfection of an activated form of Xotch into isolated retinal cells causes them to retain a neuroepithelial morphology, indicating that the continued activation of Xotch inhibits cell differentiation.
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Affiliation(s)
- R I Dorsky
- Department of Biology, University of California, San Diego, La Jolla 92093
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213
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Gu Y, Hukriede NA, Fleming RJ. Serrate expression can functionally replace Delta activity during neuroblast segregation in the Drosophila embryo. Development 1995; 121:855-65. [PMID: 7720588 DOI: 10.1242/dev.121.3.855] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serrate and Delta encode structurally related proteins in D. melanogaster that bind within a common extracellular region on the NOTCH receptor molecule. We used ectopic expression to determine if SERRATE could mediate in vivo functions parallel or antagonistic to those proposed for the putative NOTCH ligand DELTA. Our results demonstrate that Serrate can replace Delta gene function during embryonic neuroblast segregation and that expression of Serrate leads to a NOTCH-dependent suppression of achaete expression in proneural clusters. Our findings strongly suggest that SERRATE functions as an alternative ligand capable of NOTCH activation.
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Affiliation(s)
- Y Gu
- Department of Biology, University of Rochester, NY 14627
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214
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Abstract
Proper cell-cell adhesion and communication are essential for normal development and are often perturbed during tumor formation. We have come to realize that cell-cell junctions not only mediate intercellular adhesion, but also serve as organizing centers for specific cell-cell signaling pathways. The characterization of protein components of adhesive and tight/septate junctions in vertebrates and Drosophila is reviewed, and their roles in adhesion and signaling discussed. Many molecules that mediate intercellular signaling, including certain tumor suppressor gene products, are localized to particular cell-cell junctions, suggesting that disruption of junctional signaling pathways contributes to tumorigenesis.
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Affiliation(s)
- C Kirkpatrick
- Department of Biology, University of North Carolina, Chapel Hill 27599-3280, USA
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215
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Baker NE, Zitron AE. Drosophila eye development: Notch and Delta amplify a neurogenic pattern conferred on the morphogenetic furrow by scabrous. Mech Dev 1995; 49:173-89. [PMID: 7734391 DOI: 10.1016/0925-4773(94)00314-d] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Loss of function mutations of scabrous and conditional alleles of Notch and Delta affect the pattern of morphogenetic furrow development. By studying differentiation of R8 cells, the first photoreceptor neuron subtype to differentiate, we show that all furrow cells pass through an R8-competent stage. Function of Notch and scabrous is necessary if most of these cells are to attain other cell fates. The scabrous gene confers a regular pattern on the morphogenetic furrow, restricting R8 differentiation to alternating groups of cells. Notch and Delta function to restrict the R8 fate to a single cell in each group. Without scabrous gene function, action of Notch and Delta on the entire morphogenetic furrow results in a disorganised pattern of ommatidia arising from a disorganised array of single R8 cells. Aspects of the scabrous mutant phenotype also suggest a secondary role in selecting a single R8 cell from competent clusters. We show that scabrous expression preceeds changes in the apical profiles of morphogenetic furrow cells that identify ommatidial precurf1p4cells, and also preceeds changes in levels of Notch and Delta expression. The pattern of initiation of sca expression depends on sca gene function, indicating that patterning of the morphogenetic furrow depends on the pattern of posterior columns. Our results suggest that in the eye, Notch and Delta amplify and refine a morphogenetic landscape generated by scabrous. Cell determination in other tissues and organisms might also be molded in a two-step process where initial inhomogeneities determined by one protein provide a context for subsequent development.
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Affiliation(s)
- N E Baker
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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216
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217
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Crittenden SL, Troemel ER, Evans TC, Kimble J. GLP-1 is localized to the mitotic region of the C. elegans germ line. Development 1994; 120:2901-11. [PMID: 7607080 DOI: 10.1242/dev.120.10.2901] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In C. elegans, germline mitosis depends on induction by the somatic distal tip cell (DTC) and on activity of the glp-1 gene. Using antibodies to GLP-1 protein, we have examined GLP-1 on western blots and by immunocytochemistry. GLP-1 is tightly associated with membranes of mitotic germline cells, supporting its identification as an integral membrane protein. Furthermore, GLP-1 is localized within the germ line to the mitotic region, consistent with the model that GLP-1 acts as a membrane receptor for the distal tip cell signal. Unexpectedly, GLP-1 and the zone of mitosis extend further than the DTC processes. We present three models by which the DTC may influence GLP-1 activity and thereby determine the zone of mitosis. The spatial restriction of GLP-1 appears to be controlled at the translational level in hermaphrodites. We suggest that down-regulation of GLP-1 may be required to effect the transition from mitosis into meiosis.
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Affiliation(s)
- S L Crittenden
- Laboratory of Molecular Biology, University of Wisconsin 53706, USA
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218
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Kopan R, Nye JS, Weintraub H. The intracellular domain of mouse Notch: a constitutively activated repressor of myogenesis directed at the basic helix-loop-helix region of MyoD. Development 1994; 120:2385-96. [PMID: 7956819 DOI: 10.1242/dev.120.9.2385] [Citation(s) in RCA: 340] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We show that Myf-5 and mNotch mRNA are both present in the presomitic mesoderm before muscle cell commitment and before muscle structural gene activation. The failure of presomitic mesoderm to respond to Myf-5 and express myogenic properties implies that there may be a mechanism in presomitic mesoderm to suppress muscle differentiation. Here we show that ectopic expression of the intracellular domain of mNotch (mNotchIC) functions as a constitutively activated repressor of myogenesis both in cultured cells and in frog embryos. Mutagenesis experiments indicate that the target for inactivation by mNotch is the MyoD basic helix-loop-helix domain. mNotchIC contains a nuclear localization signal and localizes to the nucleus. Removal of the nuclear localization signal (NLS) reduces nuclear localization and diminishes the inhibition of myogenesis caused by Myf-5 or MyoD. Additional experiments show that the CDC10/SWI6/ankyrin repeats are also necessary for myogenic inhibition.
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Affiliation(s)
- R Kopan
- Fred Hutchinson Cancer Research Center, Howard Hughes Medical Institute, Seattle, WA 98104
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219
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Singson A, Leviten MW, Bang AG, Hua XH, Posakony JW. Direct downstream targets of proneural activators in the imaginal disc include genes involved in lateral inhibitory signaling. Genes Dev 1994; 8:2058-71. [PMID: 7958878 DOI: 10.1101/gad.8.17.2058] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In Drosophila imaginal discs, the spatially restricted activities of the achaete (ac) and scute (sc) proteins, which are transcriptional activators of the basic-helix-loop-helix class, define proneural clusters (PNCs) of potential sensory organ precursor (SOP) cells. Here, we report the identification of several genes that are direct downstream targets of ac-sc activation, as judged by the following criteria. The genes are expressed in the PNCs of the wing imaginal disc in an ac-sc-dependent manner; the proximal promoter regions of all of these genes contain one or two high-affinity ac-sc binding sites, which define the novel consensus GCAGGTG(T/G)NNNYY; where tested, these binding sites are required in vivo for PNC expression of promoter-reporter fusion genes. Interestingly, these ac-sc target genes, including Bearded, Enhancer of split m7, Enhancer of split m8, and scabrous, are all known or believed to function in the selection of a single SOP from each PNC, a process mediated by inhibitory cell-cell interactions. Thus, one of the earliest steps in adult peripheral neurogenesis is the direct activation by proneural proteins of genes involved in restricting the expression of the SOP cell fate.
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Affiliation(s)
- A Singson
- Department of Biology, University of California San Diego, La Jolla 92093-0322
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220
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Fristrom D, Gotwals P, Eaton S, Kornberg TB, Sturtevant M, Bier E, Fristrom JW. Blistered: a gene required for vein/intervein formation in wings of Drosophila. Development 1994; 120:2661-71. [PMID: 7956840 DOI: 10.1242/dev.120.9.2661] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have characterized the blistered (bs) locus phenotypically, genetically and developmentally using a set of new bs alleles. Mutant defects range from wings with ectopic veins and intervein blisters to completely ballooned wings where the distinction between vein and intervein is lost. Mosaic analyses show that severe bs alleles behave largely autonomously; homozygous patches having vein-like properties. Developmental analyses were undertaken using light and electron microscopy of wild-type and bs wings as well as confocal microscopy of phalloidin- and laminin-stained preparations. bs defects were first seen early in the prepupal period with the failure of apposition of dorsal and ventral wing epithelia. Correspondingly, during definitive vein/intervein differentiation in the pupal period (18-36 hours after puparium formation), the extent of dorsal/ventral reapposition is reduced in bs wings. Regions of the wing that fail to become apposed differentiate properties of vein cells; i.e. become constricted apically and acquire a laminin-containing matrix basally. To further understand bs function, we examined genetic interactions between various bs alleles and mutants of two genes whose products have known functions in wing development. (i) rhomboid, a component of the EGF-R signalling pathway, is expressed in vein cells and is required for specification of vein cell fate. rhove mutations (lacking rhomboid in wings) suppress the excess vein formation and associated with bs. Conversely, rho expression in prepupal and pupal bs wings is expanded in the regions of increased vein formation. (ii) The integrin genes, inflated and myospheroid, are expressed in intervein cells and are required for adhesion between the dorsal and ventral wing surfaces. Loss of integrin function results in intervein blisters. Integrin mutants interact with bs mutants to increase the frequency of intervein blisters but do not typically enhance vein defects. Both developmental and genetic analyses suggest that the bs product is required during metamorphosis for the initiation of intervein development and the concomitant inhibition of vein development.
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Affiliation(s)
- D Fristrom
- Department of Molecular and Cell Biology, University of California, Berkeley 94720
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221
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Abstract
Extensive genetic and molecular analyses indicate that Notch acts as a transmembrane receptor in an evolutionarily conserved cell interaction mechanism that appears to control a common step in the progression of an uncommitted cell towards the differentiated state. In Drosophila, Notch mutations were shown to affect the development of a broad spectrum of tissues, including the wing. We found that mutations in the segment polarity gene wingless are capable of acting as dominant enhancers of notchoid, a recessive Notch allele affecting the wing. The Wingless protein is homologous to the mammalian proto-oncoprotein Wnt-1 and is thought to act as the signal in a cell interaction mechanism that specifies differentiation of the embryonic epidermis as well as imaginal structures such as the wing. Although some components of the Wingless signal transduction pathway have been identified, the receptor for Wingless remains elusive. This genetic link between the Wingless and Notch pathways has been further examined by determining the relative expression patterns and subcellular localization of Notch and Wingless in mutant and wild-type backgrounds. We find that Notch is necessary for the implementation of the Wingless signal in specifying normal wing development. We discuss the possibility that Notch is directly involved in the reception of Wingless in the light of current models for the developmental action of Notch.
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Affiliation(s)
- H K Hing
- Howard Hughes Medical Institute, Yale University, School of Medicine, New Haven, CT 06536-0812
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222
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The concentration of B52, an essential splicing factor and regulator of splice site choice in vitro, is critical for Drosophila development. Mol Cell Biol 1994. [PMID: 8035814 DOI: 10.1128/mcb.14.8.5360] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
B52 is a Drosophila melanogaster protein that plays a role in general and alternative splicing in vitro. It is homologous to the human splicing factor ASF/SF2 which is essential for an early step(s) in spliceosome assembly in vitro and also regulates 5' and 3' alternative splice site choice in a concentration-dependent manner. In vitro, B52 can function as both a general splicing factor and a regulator of 5' alternative splice site choice. Its activity in vivo, however, is largely uncharacterized. In this study, we have further characterized B52 in vivo. Using Western blot (immunoblot) analysis and whole-mount immunofluorescence, we demonstrate that B52 is widely expressed throughout development, although some developmental stages and tissues appear to have higher B52 levels than others do. In particular, B52 accumulates in ovaries, where it is packaged into the developing egg and is localized to nuclei by the late blastoderm stage of embryonic development. We also overexpressed this protein in transgenic flies in a variety of developmental and tissue-specific patterns to examine the effects of altering the concentration of this splicing factor in vivo. We show that, in many cell types, changing the concentration of B52 adversely affects the development of the organism. We discuss the significance of these observations with regard to previous in vitro results.
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223
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Kraus ME, Lis JT. The concentration of B52, an essential splicing factor and regulator of splice site choice in vitro, is critical for Drosophila development. Mol Cell Biol 1994; 14:5360-70. [PMID: 8035814 PMCID: PMC359055 DOI: 10.1128/mcb.14.8.5360-5370.1994] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
B52 is a Drosophila melanogaster protein that plays a role in general and alternative splicing in vitro. It is homologous to the human splicing factor ASF/SF2 which is essential for an early step(s) in spliceosome assembly in vitro and also regulates 5' and 3' alternative splice site choice in a concentration-dependent manner. In vitro, B52 can function as both a general splicing factor and a regulator of 5' alternative splice site choice. Its activity in vivo, however, is largely uncharacterized. In this study, we have further characterized B52 in vivo. Using Western blot (immunoblot) analysis and whole-mount immunofluorescence, we demonstrate that B52 is widely expressed throughout development, although some developmental stages and tissues appear to have higher B52 levels than others do. In particular, B52 accumulates in ovaries, where it is packaged into the developing egg and is localized to nuclei by the late blastoderm stage of embryonic development. We also overexpressed this protein in transgenic flies in a variety of developmental and tissue-specific patterns to examine the effects of altering the concentration of this splicing factor in vivo. We show that, in many cell types, changing the concentration of B52 adversely affects the development of the organism. We discuss the significance of these observations with regard to previous in vitro results.
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Affiliation(s)
- M E Kraus
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
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224
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Fehon RG, Dawson IA, Artavanis-Tsakonas S. A Drosophila homologue of membrane-skeleton protein 4.1 is associated with septate junctions and is encoded by the coracle gene. Development 1994; 120:545-57. [PMID: 8162854 DOI: 10.1242/dev.120.3.545] [Citation(s) in RCA: 228] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Protein 4.1 functions to link transmembrane proteins with the underlying spectrin/actin cytoskeleton. To permit a genetic analysis of the developmental role and cellular functions of this membrane-skeletal protein, we have identified and characterized its Drosophila homologue (termed D4.1). D4.1 is localized to the septate junctions of epithelial cells and is encoded by the coracle gene, a new locus whose primary mutant phenotype is a failure in dorsal closure. In addition, coracle mutations dominantly suppress Ellipse, a hypermorphic allele of the Drosophila EGF-receptor homologue. These data indicate that D4.1 is associated with the septate junction, and suggest that it may play a role in cell-cell interactions that are essential for normal development.
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Affiliation(s)
- R G Fehon
- Department of Zoology, Duke University, Durham, North Carolina 27708-0325
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225
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Diederich RJ, Matsuno K, Hing H, Artavanis-Tsakonas S. Cytosolic interaction between deltex and Notch ankyrin repeats implicates deltex in the Notch signaling pathway. Development 1994; 120:473-81. [PMID: 8162848 DOI: 10.1242/dev.120.3.473] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Genetic data from Drosophila have suggested a functional relationship between the novel cytoplasmic protein encoded by the deltex locus and the transmembrane receptor encoded by Notch. We have demonstrated a direct interaction between these proteins from expression studies conducted in cultured cells, in yeast, and in the imaginal wing disc. deltex binds specifically to the Notch ankyrin repeats, a region that is crucial for Notch signaling and that constitutes the most conserved domain among Notch family members. In addition, we present a new Notch allele, Nsu42c, that is associated with a missense mutation within the fifth ankyrin repeat. In addition to representing a new class of viable Notch allele, this mutation behaves similarly to mutations of deltex and further implicates the ankyrin repeats in Notch function.
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Affiliation(s)
- R J Diederich
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06536-0812
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226
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Busseau I, Diederich RJ, Xu T, Artavanis-Tsakonas S. A member of the Notch group of interacting loci, deltex encodes a cytoplasmic basic protein. Genetics 1994; 136:585-96. [PMID: 8150285 PMCID: PMC1205810 DOI: 10.1093/genetics/136.2.585] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Prior genetic studies have suggested a functional relationship between the product of the deltex gene and those of three of the so-called "neurogenic" loci, Notch, Delta and mastermind. To gain further insight into this relationship, we have proceeded with a molecular characterization of deltex. We report that deltex encodes a maternally and zygotically expressed transcript that conceptually translates to a basic protein of novel sequence. Immunolocalization of the protein reveals an apparently ubiquitous distribution in embryonic and imaginal tissues. Because our detection methods also reveal a very low level of protein accumulation within the cytoplasm of cells, we have used transgenic flies to confirm this observation by ectopically expressing deltex under the control of a heat shock gene promoter. The resulting overexpression rescues deltex mutant defects but does not produce any obvious phenotypic abnormalities in otherwise wild-type flies. Finally, we examine genetically several Supressor of deltex mutations for evidence of functional integration with deltex and other neurogenic genes. We demonstrate that in addition to suppressing all adult morphological defects of deltex alleles, these suppressors also are capable of suppressing most synergistic effects involving deltex and Notch, Delta and mastermind.
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Affiliation(s)
- I Busseau
- Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
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227
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Mechanisms of Neurogenesis in Drosophila Melanogaster. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s1566-3116(08)60005-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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228
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Campos-Ortega JA. Genetic mechanisms of early neurogenesis in Drosophila melanogaster. JOURNAL OF PHYSIOLOGY, PARIS 1994; 88:111-22. [PMID: 7833855 DOI: 10.1016/0928-4257(94)90022-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The neuroectoderm of insects contains an initially indifferent population of cells which during later development will give rise to the progenitor cells of the neural and epidermal lineages. Experimental evidence indicates that cellular interactions determine which cells will adopt each one of these fates. The invoked cell interactions are assumed to be mediated by the products of several genes forming a complex, not yet well understood network of interrelationships. Elements of this network are the proteins encoded by Delta and Notch, which appear to convey the regulatory signals between the cells; the proteins encoded by the achaete-scute gene complex, which regulate neural development, and the proteins encoded by the Enhancer of split gene complex, which give neuroectodermal cells access to epidermal development. The proneural genes appear to be the key elements in the regulation of the cellular decision.
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229
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Affiliation(s)
- M E Fortini
- Howard Hughes Medical Institute, Department of Biology, Yale University, New Haven, Connecticut 06536
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230
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Gay NJ, Ntwasa M. The Drosophila ankyrin repeat protein cactus has a predominantly alpha-helical secondary structure. FEBS Lett 1993; 335:155-60. [PMID: 8253187 DOI: 10.1016/0014-5793(93)80720-f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cactus protein is the Drosophila homologue of the mammalian I kappa B family of cytoplasmic anchor proteins. We have expressed in E. coli and purified a cactus fusion protein, CACT-Bgl. CACT-Bgl protein contains the six ankyrin repeat sequences which are necessary for specific binding to the Drosophila rel family transcription factor dorsal. We show that the purified CACT-Bgl protein can bind specifically to dorsal and, using circular dichroism spectroscopy, that the protein adopts a largely alpha-helical secondary structure. A further analysis of the ankyrin repeat domains of cactus, using an improved secondary structure prediction program indicates that the N-terminal of the repeat will form into a loop structure and the C-terminal section into an interrupted, amphipathic alpha-helix. On the basis of these findings we propose that the ankyrin repeats of cactus fold together into helical bundles interconnected by diverged loops.
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Affiliation(s)
- N J Gay
- Department of Biochemistry, University of Cambridge, UK
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231
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Fortini ME, Rebay I, Caron LA, Artavanis-Tsakonas S. An activated Notch receptor blocks cell-fate commitment in the developing Drosophila eye. Nature 1993; 365:555-7. [PMID: 8413612 DOI: 10.1038/365555a0] [Citation(s) in RCA: 252] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The Notch locus of Drosophila melanogaster encodes a 2,703-amino-acid transmembrane protein required for a variety of developmental processes, including neurogenesis, oogenesis and ommatidial assembly. The Notch protein contains a large extracellular domain of 36 epidermal growth factor-like repeats as well as three Notch/Lin-12 repeats and an intracellular domain with 6 Cdc10/ankyrin repeats, motifs that are highly conserved in several vertebrate Notch homologues. Truncation of the extracellular domain of the Drosophila Notch protein produces an activated receptor, as judged by its ability to cause phenotypes similar to gain-of-function alleles of duplications of the Notch locus. Equivalent truncations of vertebrate Notch-related proteins have been associated with malignant neoplasma and other developmental abnormalities. We present here an analysis of activated Notch function at single-cell resolution in the Drosophila compound eye. We find that overexpression of full-length Notch in defined cell types has no apparent effects but that overexpression of activated Notch in the same cells transiently blocks their proper cell-fate commitment, causing them either to adopt incorrect cell fates or to differentiate incompletely. Moreover, an activated Notch protein lacking the transmembrane domain is translocated to the nucleus, raising the possibility that Notch may participate directly in nuclear events.
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Affiliation(s)
- M E Fortini
- Department of Cell Biology, Yale University, New Haven, Connecticut 06536
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232
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Campos-Ortega JA. Mechanisms of early neurogenesis in Drosophila melanogaster. JOURNAL OF NEUROBIOLOGY 1993; 24:1305-27. [PMID: 8228961 DOI: 10.1002/neu.480241005] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The neuroectoderm of insects contains an initially indifferent population of cells which during later development will give rise to the progenitor cells of the neural and epidermal lineages. Experimental evidence indicates that cellular interactions determine which cells will adopt each one of these fates. Transplantation experiments suggest that a signal with neuralising character is required to stabilize the primary neural fate in 25% of all the neuroectodermal cells, which will develop as neuroblasts, and that an epidermalising signal contributes to suppress the neural fate in the remaining 75% of the cells, allowing in this way their development as epidermal progenitor cells. The invoked cell interactions are assumed to be mediated by the products of several genes forming a complex, not yet well understood network of interrelationships. Elements of this network are the proteins encoded by Delta and Notch, which appear to convey the regulatory signals between the cells; the proteins encoded by the achaete-scute gene complex, which regulate neural development; and the proteins encoded by the Enhancer of split gene complex, which give neuroectodermal cells access to epidermal development.
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233
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Bierkamp C, Campos-Ortega JA. A zebrafish homologue of the Drosophila neurogenic gene Notch and its pattern of transcription during early embryogenesis. Mech Dev 1993; 43:87-100. [PMID: 8297791 DOI: 10.1016/0925-4773(93)90027-u] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We describe here the primary structure of a zebrafish homologue of the Drosophila neurogenic gene Notch and its pattern of mRNA accumulation during embryogenesis. The gene produces a 8.5 kb transcript encoding a putative transmembrane protein with a high degree of sequence similarity to members of the Notch family, comprising 36 EGF-like repeats, three lin-12/Notch repeats, six cdc10/SWI6 repeats, OPA repeats and a PEST sequence. Transcription of the zebrafish Notch gene is spatially and temporally regulated. A high density of transcripts, most probably of maternal origin, can already be detected in the 2-cell stage. During pregastrulation stages, RNA is present in all cells. However, following gastrulation, transcripts accumulate in specific regions of the embryo following a rapidly changing pattern. In some of these regions, cell divisions take place at the time of Notch expression, in others processes of cell differentiation. This holds true for various mesodermal derivatives, such as the prospective notochord, and for different neural primordia, such as the neural plate and the brain vesicles. This pattern of transcript accumulation suggests a role for the zebrafish Notch homologue in processes of regionalization and cell diversification.
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Affiliation(s)
- C Bierkamp
- Institut für Entwicklungsbiologie, Universität zu Köln, Germany
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234
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Lieber T, Kidd S, Alcamo E, Corbin V, Young MW. Antineurogenic phenotypes induced by truncated Notch proteins indicate a role in signal transduction and may point to a novel function for Notch in nuclei. Genes Dev 1993; 7:1949-65. [PMID: 8406001 DOI: 10.1101/gad.7.10.1949] [Citation(s) in RCA: 367] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Loss of any one of several neurogenic genes of Drosophila results in overproduction of embryonic neuroblasts at the expense of epidermoblasts. In this paper a variety of altered Notch proteins are expressed in transgenic flies. Dominant lethal, antineurogenic phenotypes were produced by expression of three classes of mutant proteins: (1) a protein comprised of the cytoplasmic domain of Notch and devoid of sequences permitting membrane association; (2) a transmembrane protein lacking the extracellular, lin12/Notch repeats; and (3) transmembrane proteins carrying amino acid substitutions replacing one or both extracellular cysteines thought to be involved in Notch dimerization. These Notch proteins not only suppress the neural hypertrophy observed in Notch- embryos, but also generate a phenotype in which elements of the embryonic nervous system are underproduced. Action of the intracellular cdc10 repeats appears to be essential for wild-type Notch function or for the antineurogenic activity of these proteins. The activities of the dominant, gain-of-function proteins indicate that Notch functions as a signal transducing receptor during ectoderm development. Production of antineurogenic Notch proteins in embryos deficient for the other neurogenic genes allowed functional dependencies to be established. Delta, mastermind, bigbrain, and neuralized appear to function in elaboration of a signal upstream of Notch. Genes of the Enhancer of split complex act after Notch. The cytoplasmic domain of Notch contains nuclear localization sequences that function in cultured cells, and one of the Notch antineurogenic proteins, the cytoplasmic domain, accumulates in nuclei in vivo.
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Affiliation(s)
- T Lieber
- Laboratory of Genetics, Rockefeller University, New York, New York 10021
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235
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Green P, Hartenstein AY, Hartenstein V. The embryonic development of the Drosophila visual system. Cell Tissue Res 1993; 273:583-98. [PMID: 8402833 DOI: 10.1007/bf00333712] [Citation(s) in RCA: 184] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have used electron-microscopic studies, bromodeoxyuridine (BrdU) incorporation and antibody labeling to characterize the development of the Drosophila larval photoreceptor (or Bolwig's) organ and the optic lobe, and have investigated the role of Notch in the development of both. The optic lobe and Bolwig's organ develop by invagination from the posterior procephalic region. After cells in this region undergo four postblastoderm divisions, a total of approximately 85 cells invaginate. The optic lobe invagination loses contact with the outer surface of the embryo and forms an epithelial vesicle attached to the brain. Bolwig's organ arises from the ventralmost portion of the optic lobe invagination, but does not become incorporated in the optic lobe; instead, its 12 cells remain in the head epidermis until late in embryogenesis when they move in conjunction with head involution to reach their final position alongside the pharynx. Early, before head involution, the cells of Bolwig's organ form a superficial group of 7 cells arranged in a 'rosette' pattern and a deep group of 5 cells. Later, all neurons move out of the surface epithelium. Unlike adult photoreceptors, they do not form rhabdomeres; instead, they produce multiple, branched processes, which presumably carry the photopigment. Notch is essential for two aspects of the early development of the visual system. First, it delimits the number of cells incorporated into Bolwig's organ. Second, it is required for the maintenance of the epithelial character of the optic lobe cells during and after its invagination.
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Affiliation(s)
- P Green
- Department of Biology, University of California Los Angeles 90024
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236
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Abstract
The lin-12 gene of C. elegans and the Notch gene of D. melanogaster encode structurally related transmembrane proteins that mediate intercellular signaling. We show that truncated forms of these proteins consisting of only the intracellular domains cause cell fate transformations associated with constitutive activity in their respective organisms. This activity does not depend on endogenous gene function. Our results indicate that the intracellular domains of Lin-12 and Notch have intrinsic activity and that the principal role of the extracellular domains in the intact proteins is to regulate this activity. Our results also suggest that equivalent truncated forms of lin-12/Notch family members in vertebrates, including known oncogenes, are similarly active.
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Affiliation(s)
- G Struhl
- Howard Hughes Medical Institute, Department of Genetics and Development, Columbia University College of Physicians and Surgeons, New York, New York 10032
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237
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Rebay I, Fehon RG, Artavanis-Tsakonas S. Specific truncations of Drosophila Notch define dominant activated and dominant negative forms of the receptor. Cell 1993; 74:319-29. [PMID: 8343959 DOI: 10.1016/0092-8674(93)90423-n] [Citation(s) in RCA: 333] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The Notch gene of Drosophila plays an important role in cell fate specification throughout development. To investigate the functions of specific structural domains of the Notch protein in vivo, a series of deletion mutants have been ectopically expressed under the hsp70 heat shock promoter. Two classes of dominant phenotypes are observed, one suggestive of Notch loss-of-function mutations and the other of Notch gain-of-function mutations. Dominant activated phenotypes result from overexpression of a protein lacking most extracellular sequences, while dominant negative phenotypes result from overexpression of a protein lacking most intracellular sequences. These results support the notion that Notch functions as a receptor whose extracellular domain mediates ligand binding, resulting in the transmission of developmental signals by the cytoplasmic domain. Finally, the phenotypes observed suggest that the cdc 10/ankyrin repeat region within the intracellular domain plays an essential role in the postulated signal transduction events.
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Affiliation(s)
- I Rebay
- Howard Hughes Medical Institute, Department of Cell Biology, Yale University, New Haven, Connecticut 06536-0812
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238
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Coffman CR, Skoglund P, Harris WA, Kintner CR. Expression of an extracellular deletion of Xotch diverts cell fate in Xenopus embryos. Cell 1993; 73:659-71. [PMID: 8500162 DOI: 10.1016/0092-8674(93)90247-n] [Citation(s) in RCA: 312] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Xotch is a Xenopus homolog of Notch, a receptor involved in cell fate decisions in Drosophila. Using an extracellular deletion construct, Xotch delta E, we show that Xotch has a similar role in Xenopus embryos. Broad expression causes the loss of dorsal structures and the expansion and disorganization of the brain. Single blastomere injections of Xotch delta E induce autonomous neural and mesodermal hypertrophy, even in the absence of cell division. Xotch delta E inhibits the early expression of epidermal and neural crest markers yet enhances and extends the response of animal caps to mesodermal and neural induction. Our data suggest a mechanism for the function of Notch homologs in which they delay differentiation and leave undetermined cells competent to respond to later inductive signals.
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Affiliation(s)
- C R Coffman
- Department of Biology, University of California, San Diego, La Jolla 92093
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239
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Kopan R, Weintraub H. Mouse notch: expression in hair follicles correlates with cell fate determination. J Cell Biol 1993; 121:631-41. [PMID: 8486742 PMCID: PMC2119559 DOI: 10.1083/jcb.121.3.631] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Many vertebrate tissues, including skin, are known to develop as a consequence of epithelial-mesenchymal interactions. Much less is known about the role of cell-cell interaction within the epithelial or the mesenchymal compartments in morphogenesis. To investigate cell-cell interactions during skin development, and the potential role of the Notch homolog in this process, we cloned the mouse homolog of Notch (mNotch) and studied its expression pattern, starting as early as mesoderm formation. The novel application of double-labeled in situ hybridization in vertebrates allowed high resolution analysis to follow the fate of mNotch expressing cells directly. In comparison with the distribution of Id mRNA, analysis confirmed that in the hair follicle high levels of mNotch are expressed exclusively in the epithelial compartment. Hair follicle matrix cells start expressing mNotch as different cell types become distinguishable in the developing follicle. mNotch mRNA expression persists throughout the growth phase of the follicle and maintains the same expression profile in the second hair cycle. The cells in the follicle that undergo a phase of high level mNotch expression are in transition from mitotic precursors to several discreet, differentiating cell types. Our observations point out that both in time (during development) and in space (by being removed one cell layer from the dermal papilla) mNotch expression is clearly separated from the inductive interactions. This is a novel finding and suggests that mNotch is important for follicular differentiation and possibly cell fate selection within the follicle.
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Affiliation(s)
- R Kopan
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98104
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240
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Heitzler P, Simpson P. Altered epidermal growth factor-like sequences provide evidence for a role of Notch as a receptor in cell fate decisions. Development 1993; 117:1113-23. [PMID: 8325237 DOI: 10.1242/dev.117.3.1113] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In Drosophila each neural precursor is chosen from a group of cells through cell interactions mediated by Notch and Delta which may function as receptor and ligand (signal), respectively, in a lateral signalling pathway. The cells of a group are equipotential and express both Notch and Delta. Hyperactive mutant Notch molecules, (Abruptex), probably have an enhanced affinity for the ligand. When adjacent to wild-type cells, cells bearing the Abruptex proteins are unable to produce the signal. It is suggested that in addition to the binding of Notch molecules on one cell to the Delta molecules of opposing cells, the Notch and Delta proteins on the surface of the same cell may interact. Binding between a cell's own Notch and Delta molecules would alter the availability of these proteins to interact with their counterparts on adjacent cells.
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Affiliation(s)
- P Heitzler
- Laboratoire de Génétique moléculaire des Eucaryotes du CNRS, Unité 184 de Biologie Moléculaire, Strasbourg, France
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241
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Kooh PJ, Fehon RG, Muskavitch MA. Implications of dynamic patterns of Delta and Notch expression for cellular interactions during Drosophila development. Development 1993; 117:493-507. [PMID: 8330521 DOI: 10.1242/dev.117.2.493] [Citation(s) in RCA: 167] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Delta and Notch function are required for cell fate specification in numerous tissues during embryonic and postembryonic Drosophila development. Delta is expressed by all members of interacting cell populations within which fates are being specified and is subsequently down-regulated as cells stably adopt particular fates. Multiphasic expression in the derivatives of many germ layers implies successive requirements for Delta function in a number of tissues. At the cellular level, Delta and Notch expression are generally coincident within developing tissues. At the subcellular level, Delta and Notch are localized in apparent endocytic vesicles during down-regulation from the surfaces of interacting cells, implying an interaction consistent with their proposed roles as signal and receptor in cellular interactions during development.
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Affiliation(s)
- P J Kooh
- Howard Hughes Medical Institute, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202
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242
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Giniger E, Jan LY, Jan YN. Specifying the path of the intersegmental nerve of the Drosophila embryo: a role for Delta and Notch. Development 1993; 117:431-40. [PMID: 8330518 DOI: 10.1242/dev.117.2.431] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The intersegmental nerve (ISN) of the Drosophila embryo follows a reproducible course near the anterior border of each segment. Based on the experiments reported here, we suggest that growth of the axons constituting the nerve is guided, in part, by the transmembrane proteins Delta and Notch. In particular, we suggest that expression of Delta protein on a branch of the trachea provides a path for the nerve through the lateral part of the embryo, and that the growing axons use the Notch protein on their surfaces to recognize this path. Consistent with this idea, we show that disruption of the trachea abolishes the ability of the ISN to extend through this part of the embryonic periphery. Finally, we argue that the same regulatory network that directs these peripheral axons also specifies the trajectory of part of the axonal scaffold of the central nervous system.
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Affiliation(s)
- E Giniger
- Howard Hughes Medical Institute, University of California, San Francisco 94143
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243
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Callaerts P, De Loof A. Developmental effects of monensin on Drosophila melanogaster. Dev Genes Evol 1993; 203:83-91. [PMID: 28305983 DOI: 10.1007/bf00539893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/1993] [Accepted: 03/19/1993] [Indexed: 11/25/2022]
Abstract
Extracellular matrix and membrane proteins and their correct secretion probably are key elements in morphogenesis and differentiation in Drosophila. In this study, we have analysed the effects of monensin, a Na+-H+-ionophore which blocks normal secretion, applied during cellular blastoderm formation on further development. Normal cell morphology and intercellular contacts are lost and the extracellular matrix becomes disorganized. Gastrulation is blocked and abnormal foldings can be observed. Cuticle phenotypes showed different degrees of ventral, dorsal, head and posterior defects. The results are discussed in the context of what is known about membrane and extracellular matrix proteins in Drosophila.
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Affiliation(s)
- Patrick Callaerts
- Zoological Institute, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000, Leuven, Belgium
| | - Arnold De Loof
- Zoological Institute, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000, Leuven, Belgium
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244
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Giniger E, Wells W, Jan LY, Jan YN. Tracing neurons with a kinesin-?-galactosidase fusion protein. ACTA ACUST UNITED AC 1993; 202:112-122. [DOI: 10.1007/bf00636536] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/1992] [Accepted: 10/06/1992] [Indexed: 11/29/2022]
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245
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Abstract
Notch is a cell surface receptor that mediates a wide variety of cellular interactions that specify cell fate during Drosophila development. Recently, homologs of Drosophila Notch have been isolated from Xenopus, human and rat, and the expression patterns of these vertebrate proteins suggest that they may be functionally analogous to their Drosophila counterpart. We have now identified a second rat gene that exhibits substantial nucleic and amino acid sequence identity to Drosophila Notch. This gene, designated Notch2, encodes a protein that contains all the structural motifs characteristic of a Notch protein. Thus, mammals differ from Drosophila in having more than one Notch gene. Northern and in situ hybridisation analyses in the developing and adult rat identify distinct spatial and temporal patterns of expression for Notch1 and Notch2, indicating that these genes are not redundant. These results suggest that the great diversity of cell-fate decisions regulated by Notch in Drosophila may be further expanded in vertebrates by the activation of distinct Notch proteins.
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Affiliation(s)
- G Weinmaster
- Molecular Neurobiology Laboratory, Salk Institute, San Diego, CA 92186
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246
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Hartenstein AY, Rugendorff A, Tepass U, Hartenstein V. The function of the neurogenic genes during epithelial development in the Drosophila embryo. Development 1992; 116:1203-20. [PMID: 1295737 DOI: 10.1242/dev.116.4.1203] [Citation(s) in RCA: 185] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The complex embryonic phenotype of the six neurogenic mutations Notch, mastermind, big brain, Delta, Enhancer of split and neuralized was analyzed by using different antibodies and PlacZ markers, which allowed us to label most of the known embryonic tissues. Our results demonstrate that all of the neurogenic mutants show abnormalities in many different organs derived from all three germ layers. Defects caused by the neurogenic mutations in ectodermally derived tissues fell into two categories. First, all cell types that delaminate from the ectoderm (neuroblasts, sensory neurons, peripheral glia cells and oenocytes) are increased in number. Secondly, ectodermal tissues that in the wild type form epithelial structures lose their epithelial phenotype and dissociate (optic lobe, stomatogastric nervous system) or show significant differentiative abnormalities (trachea, Malpighian tubules and salivary gland). Abnormalities in tissues derived from the mesoderm were observed in all six neurogenic mutations. Most importantly, somatic myoblasts do not fuse and/or form an aberrant muscle pattern. Cardioblasts (which form the embryonic heart) are increased in number and show differentiative abnormalities; other mesodermal cell types (fat body, pericardial cells) are significantly decreased. The development of the endoderm (midgut rudiments) is disrupted in most of the neurogenic mutations (Notch, Delta, Enhancer of split and neuralized) during at least two stages. Defects occur as early as during gastrulation when the invaginating midgut rudiments prematurely lose their epithelial characteristics. Later, the transition of the midgut rudiments to form the midgut epithelium does not occur. In addition, the number of adult midgut precursor cells that segregate from the midgut rudiments is strongly increased. We propose that, at least in the ectodermally and endodermally derived tissues, neurogenic gene function is primarily involved in interactions among cells that need to acquire or to maintain an epithelial phenotype.
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Affiliation(s)
- A Y Hartenstein
- Department of Biology, University of California, Los Angeles 90024
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247
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Stifani S, Blaumueller CM, Redhead NJ, Hill RE, Artavanis-Tsakonas S. Human homologs of a Drosophila Enhancer of split gene product define a novel family of nuclear proteins. Nat Genet 1992; 2:119-27. [PMID: 1303260 DOI: 10.1038/ng1092-119] [Citation(s) in RCA: 240] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Notch and the m9/10 gene (groucho) of the Enhancer of split (E(spI)) complex are members of the "Notch group" of genes, which is required for a variety of cell fate choices in Drosophila. We have characterized human cDNA clones encoding a family of proteins, designated TLE, that are homologous to the E(spI) m9/10 gene product, as well as a novel Notch-related protein. The TLE genes are differentially expressed and encode nuclear proteins, consistent with the presence of sequence motifs associated with nuclear functions. The structural redundancy implied by the existence of more than one TLE and Notch-homologous gene may be a feature of the human counterparts of the developmentally important Drosophila Notch group genes.
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Affiliation(s)
- S Stifani
- Howard Hughes Medical Institute, Boyer Centre for Molecular Medicine, New Haven, Connecticut
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248
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Xu T, Caron LA, Fehon RG, Artavanis-Tsakonas S. The involvement of the Notch locus in Drosophila oogenesis. Development 1992; 115:913-22. [PMID: 1451667 DOI: 10.1242/dev.115.4.913] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Notch gene in Drosophila encodes a transmembrane protein with homology to EGF that, in a variety of tissues, appears to mediate cell interactions necessary for cell fate choices. Here we demonstrate that oogenesis and spermatogenesis depend on Notch. We examine the phenotypes of the temperature-sensitive Notch allele, Nts1, and, using a monoclonal antibody, determine the cellular and subcellular distribution of Notch protein during oogenesis. We show that Nts1 is associated with a missense mutation in the extracellular, EGF homologous region of Notch and that at non-permissive temperatures oogenesis is blocked and the subcellular distribution of the protein is altered. In wild-type ovaries, Notch protein is found on the apical surface of somatically derived follicle cells, while in the germline-derived cells the protein is not polarized. These findings are discussed in view of the hypothesis that Notch acts as a multifunctional receptor to mediate developmentally important cell interactions.
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Affiliation(s)
- T Xu
- Howard Hughes Medical Institute, Yale University, Department of Cell Biology, New Haven, CT 06536-0812
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249
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Del Amo FF, Smith DE, Swiatek PJ, Gendron-Maguire M, Greenspan RJ, McMahon AP, Gridley T. Expression pattern of Motch, a mouse homolog of Drosophila Notch, suggests an important role in early postimplantation mouse development. Development 1992; 115:737-44. [PMID: 1425352 DOI: 10.1242/dev.115.3.737] [Citation(s) in RCA: 192] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Notch gene of Drosophila encodes a large transmembrane protein involved in cell-cell interactions and cell fate decisions in the Drosophila embryo. To determine if a gene homologous to Drosophila Notch plays a role in early mouse development, we screened a mouse embryo cDNA library with probes from the Xenopus Notch homolog, Xotch. A partial cDNA clone encoding the mouse Notch homolog, which we have termed Motch, was used to analyze expression of the Motch gene. Motch transcripts were detected in a wide variety of adult tissues, which included derivatives of all three germ layers. Differentiation of P19 embryonal carcinoma cells into neuronal cell types resulted in increased expression of Motch RNA. In the postimplantation mouse embryo Motch transcripts were first detected in mesoderm at 7.5 days post coitum (dpc). By 8.5 dpc, transcript levels were highest in presomitic mesoderm, mesenchyme and endothelial cells, while much lower levels were detected in neuroepithelium. In contrast, at 9.5 dpc, neuroepithelium was a major site of Motch expression. Transcripts were also abundant in cell types derived from neural crest. These data suggest that the Motch gene plays multiple roles in patterning and differentiation of the early postimplantation mouse embryo.
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Affiliation(s)
- F F Del Amo
- Department of Cell and Developmental Biology, Roche Research Center, Nutley, NJ 07110
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250
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Liu Q, Summers W. Identification of the 12-O-tetradecanoylphorbol-13-acetate-responsive enhancer of the MS gene of the Epstein-Barr virus. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49804-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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