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Weasner BP, Kumar JP. The early history of the eye-antennal disc of Drosophila melanogaster. Genetics 2022; 221:6573236. [PMID: 35460415 PMCID: PMC9071535 DOI: 10.1093/genetics/iyac041] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/04/2022] [Indexed: 12/15/2022] Open
Abstract
A pair of eye-antennal imaginal discs give rise to nearly all external structures of the adult Drosophila head including the compound eyes, ocelli, antennae, maxillary palps, head epidermis, and bristles. In the earliest days of Drosophila research, investigators would examine thousands of adult flies in search of viable mutants whose appearance deviated from the norm. The compound eyes are dispensable for viability and perturbations to their structure are easy to detect. As such, the adult compound eye and the developing eye-antennal disc emerged as focal points for studies of genetics and developmental biology. Since few tools were available at the time, early researchers put an enormous amount of thought into models that would explain their experimental observations-many of these hypotheses remain to be tested. However, these "ancient" studies have been lost to time and are no longer read or incorporated into today's literature despite the abundance of field-defining discoveries that are contained therein. In this FlyBook chapter, I will bring these forgotten classics together and draw connections between them and modern studies of tissue specification and patterning. In doing so, I hope to bring a larger appreciation of the contributions that the eye-antennal disc has made to our understanding of development as well as draw the readers' attention to the earliest studies of this important imaginal disc. Armed with the today's toolkit of sophisticated genetic and molecular methods and using the old papers as a guide, we can use the eye-antennal disc to unravel the mysteries of development.
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Affiliation(s)
- Brandon P Weasner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Justin P Kumar
- Department of Biology, Indiana University, Bloomington, IN 47405, USA,Corresponding author: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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2
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Activated HGF-c-Met Axis in Head and Neck Cancer. Cancers (Basel) 2017; 9:cancers9120169. [PMID: 29231907 PMCID: PMC5742817 DOI: 10.3390/cancers9120169] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/06/2017] [Accepted: 12/07/2017] [Indexed: 12/14/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is a highly morbid disease. Recent developments including Food and Drug Administration (FDA) approved molecular targeted agent’s pembrolizumab and cetuximab show promise but did not improve the five-year survival which is currently less than 40%. The hepatocyte growth factor receptor; also known as mesenchymal–epithelial transition factor (c-Met) and its ligand hepatocyte growth factor (HGF) are overexpressed in head and neck squamous cell carcinoma (HNSCC); and regulates tumor progression and response to therapy. The c-Met pathway has been shown to regulate many cellular processes such as cell proliferation, invasion, and angiogenesis. The c-Met pathway is involved in cross-talk, activation, and perpetuation of other signaling pathways, curbing the cogency of a blockade molecule on a single pathway. The receptor and its ligand act on several downstream effectors including phospholipase C gamma (PLCγ), cellular Src kinase (c-Src), phosphotidylinsitol-3-OH kinase (PI3K) alpha serine/threonine-protein kinase (Akt), mitogen activate protein kinase (MAPK), and wingless-related integration site (Wnt) pathways. They are also known to cross-talk with other receptors; namely epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) and specifically contribute to treatment resistance. Clinical trials targeting the c-Met axis in HNSCC have been undertaken because of significant preclinical work demonstrating a relationship between HGF/c-Met signaling and cancer cell survival. Here we focus on HGF/c-Met impact on cellular signaling in HNSCC to potentiate tumor growth and disrupt therapeutic efficacy. Herein we summarize the current understanding of HGF/c-Met signaling and its effects on HNSCC. The intertwining of c-Met signaling with other signaling pathways provides opportunities for more robust and specific therapies, leading to better clinical outcomes.
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Grebler R, Kistenpfennig C, Rieger D, Bentrop J, Schneuwly S, Senthilan PR, Helfrich-Förster C. Drosophila Rhodopsin 7 can partially replace the structural role of Rhodopsin 1, but not its physiological function. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:649-659. [PMID: 28500442 PMCID: PMC5537319 DOI: 10.1007/s00359-017-1182-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 11/25/2022]
Abstract
Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1–6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells. This speaks against a role of Rh7 as photopigment in R1–6, but does not exclude that it works in the inner photoreceptor cells.
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Affiliation(s)
- Rudi Grebler
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Christa Kistenpfennig
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
- Oxitec Ltd, 71 Innovation Drive, Milton Park, Oxford, OX14 4RQ, UK
| | - Dirk Rieger
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Joachim Bentrop
- Cell- and Neurobiology, Zoological Institute, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Stephan Schneuwly
- Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Pingkalai R Senthilan
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany.
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Tsai YC, Grimm S, Chao JL, Wang SC, Hofmeyer K, Shen J, Eichinger F, Michalopoulou T, Yao CK, Chang CH, Lin SH, Sun YH, Pflugfelder GO. Optomotor-blind negatively regulates Drosophila eye development by blocking Jak/STAT signaling. PLoS One 2015; 10:e0120236. [PMID: 25781970 PMCID: PMC4363906 DOI: 10.1371/journal.pone.0120236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 01/27/2015] [Indexed: 12/23/2022] Open
Abstract
Organ formation requires a delicate balance of positive and negative regulators. In Drosophila eye development, wingless (wg) is expressed at the lateral margins of the eye disc and serves to block retinal development. The T-box gene optomotor-blind (omb) is expressed in a similar pattern and is regulated by Wg. Omb mediates part of Wg activity in blocking eye development. Omb exerts its function primarily by blocking cell proliferation. These effects occur predominantly in the ventral margin. Our results suggest that the primary effect of Omb is the blocking of Jak/STAT signaling by repressing transcription of upd which encodes the Jak receptor ligand Unpaired.
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Affiliation(s)
- Yu-Chen Tsai
- Institute of Genetics, National Yang-Ming University, Taipei; Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan, Republic of China
| | - Stefan Grimm
- Theodor-Boveri-Institut, Biozentrum, Lehrstuhl für Genetik und Neurobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Ju-Lan Chao
- Institute of Genetics, National Yang-Ming University, Taipei; Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Shih-Chin Wang
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan, Republic of China
| | - Kerstin Hofmeyer
- Theodor-Boveri-Institut, Biozentrum, Lehrstuhl für Genetik und Neurobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Jie Shen
- Institut für Genetik, Universität Mainz, Mainz, Germany
- Department of Entomology, China Agricultural University, Beijing, China
| | | | | | - Chi-Kuang Yao
- Institute of Genetics, National Yang-Ming University, Taipei; Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Chih-Hsuan Chang
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan, Republic of China
| | - Shih-Han Lin
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan, Republic of China
| | - Y. Henry Sun
- Institute of Genetics, National Yang-Ming University, Taipei; Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- * E-mail: (YHS); (GOP)
| | - Gert O. Pflugfelder
- Theodor-Boveri-Institut, Biozentrum, Lehrstuhl für Genetik und Neurobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
- Institut für Genetik, Universität Mainz, Mainz, Germany
- * E-mail: (YHS); (GOP)
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Nowak K, Seisenbacher G, Hafen E, Stocker H. Nutrient restriction enhances the proliferative potential of cells lacking the tumor suppressor PTEN in mitotic tissues. eLife 2013; 2:e00380. [PMID: 23853709 PMCID: PMC3707060 DOI: 10.7554/elife.00380] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 06/06/2013] [Indexed: 01/20/2023] Open
Abstract
How single cells in a mitotic tissue progressively acquire hallmarks of cancer is poorly understood. We exploited mitotic recombination in developing Drosophila imaginal tissues to analyze the behavior of cells devoid of the tumor suppressor PTEN, a negative regulator of PI3K signaling, under varying nutritional conditions. Cells lacking PTEN strongly overproliferated specifically in nutrient restricted larvae. Although the PTEN mutant cells were sensitive to starvation, they successfully competed with neighboring cells by autonomous and non-autonomous mechanisms distinct from cell competition. The overgrowth was strictly dependent on the activity of the downstream components Akt/PKB and TORC1, and a reduction in amino acid uptake by reducing the levels of the amino acid transporter Slimfast caused clones of PTEN mutant cells to collapse. Our findings demonstrate how limiting nutritional conditions impact on cells lacking the tumor suppressor PTEN to cause hyperplastic overgrowth. DOI:http://dx.doi.org/10.7554/eLife.00380.001 Mutations are permanent changes to a cell’s genome. If one or more mutations result in a cell proliferating in an unregulated manner, it is referred to as a cancer cell. The generation of cancer cells is a relatively common occurrence within organisms, but these rogue cells are generally recognized and destroyed by the organism’s immune system. However, when the immune system fails to identify and eliminate cancer cells, they can proliferate to form malignant, life-threatening tumors. Mutations in a gene called PTEN are often found within cells that develop into cancerous tumors. This gene is normally expressed as a protein that is involved in the regulation of cell division, preventing cells from growing and dividing too quickly. However, when the protein PTEN is absent or non-functional, cells experience enhanced growth, proliferation, and survival. Such cells are also thought to be resistant to nutrient restriction, but the mechanism responsible for this resistance is not well understood. Here, Nowak et al. investigate the behavior of cells lacking PTEN in a fly model under a variety of nutritional conditions. When the supply of nutrients is limited, cells lacking PTEN shift resources from cell growth to cell multiplication. This appears to allow PTEN-deficient cells to outcompete neighboring wild-type cells; Nowak et al. suggest these rapidly proliferating cells are capable of effectively hoarding nutrient stores, both in their immediate vicinity and organism-wide. Further studies that focus on changes in gene expression may be able to uncover the mechanism that allows PTEN-deficient cells to proliferate when nutrients are restricted. Moreover, by shedding light on a factor that has an important influence on tumor development, these results may have implications for cancer treatment strategies. DOI:http://dx.doi.org/10.7554/eLife.00380.002
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Affiliation(s)
- Katarzyna Nowak
- Institute of Molecular Systems Biology , ETH Zürich , Zürich , Switzerland
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Abstract
Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases.
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Affiliation(s)
- Richelle Sopko
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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7
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Aberrant activation of ROS1 represents a new molecular defect in chronic myelomonocytic leukemia. Leuk Res 2013; 37:520-30. [DOI: 10.1016/j.leukres.2013.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 01/10/2013] [Accepted: 01/18/2013] [Indexed: 02/08/2023]
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Abstract
Since the discovery of a single white-eyed male in a population of red eyed flies over 100 years ago (Morgan, 1910), the compound eye of the fruit fly, Drosophila melanogaster, has been a favorite experimental system for identifying genes that regulate various aspects of development. For example, a fair amount of what we know today about enzymatic pathways and vesicular transport is due to the discovery and subsequent characterization of eye color mutants such as white. Likewise, our present day understanding of organogenesis has been aided considerably by studies of mutations, such as eyeless, that either reduce or eliminate the compound eyes. But by far the phenotype that has provided levers into the greatest number of experimental fields has been the humble "rough" eye. The fly eye is composed of several hundred unit-eyes that are also called ommatidia. These unit eyes are packed into a hexagonal array of remarkable precision. The structure of the eye is so precise that it has been compared with that of a crystal (Ready et al., 1976). Even the slightest perturbations to the structure of the ommatidium can be visually detected by light or electron microscopy. The cause for this is two-fold: (1) any defect that affects the hexagonal geometry of a single ommatidium can and will disrupt the positioning of surrounding unit eyes thereby propagating structural flaws and (2) disruptions in genes that govern the development of even a single cell within an ommatidium will affect all unit eyes. In both cases, the effect is the visual magnification of even the smallest imperfection. Studies of rough eye mutants have provided key insights into the areas of cell fate specification, lateral inhibition, signal transduction, transcription factor networks, planar cell polarity, cell proliferation, and programmed cell death just to name a few. This review will attempt to summarize the key steps that are required to assemble each ommatidium.
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Affiliation(s)
- Justin P Kumar
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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9
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Katanaev VL, Kryuchkov MV. The eye of Drosophila as a model system for studying intracellular signaling in ontogenesis and pathogenesis. BIOCHEMISTRY (MOSCOW) 2012; 76:1556-81. [DOI: 10.1134/s0006297911130116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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10
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El-Deeb IM, Yoo KH, Lee SH. ROS receptor tyrosine kinase: a new potential target for anticancer drugs. Med Res Rev 2010; 31:794-818. [PMID: 20687158 DOI: 10.1002/med.20206] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
ROS kinase is one of the last two remaining orphan receptor tyrosine kinases with an as yet unidentified ligand. The normal functions of human ROS kinase in different body tissues have not been fully identified so far. However, the ectopic expression, as well as the production of variable mutant forms of ROS kinase has been reported in a number of cancers, such as glioblastoma multiforme, and non-small cell lung cancer, suggesting a role for ROS kinase in deriving such tumors. It is thought also that c-ROS gene may have a role in some cardiovascular diseases, and the fact that homozygous male mice targeted against c-ROS gene are healthy but infertile, has inspired researchers to think about ROS inhibition as a method for development of new male contraceptives. The recent discovery of new selective and potent inhibitors for ROS kinase, along with the development of new specific diagnostic methods for the detection of ROS fusion proteins, raises the importance of using these selective inhibitors for targeting ROS mutations as a new method for treatment of cancers harboring such genes. This review focuses on the ectopic expression of ROS and its fusion proteins in different cancer types and highlights the importance of targeting these proteins for treatment of substantial cancers. It describes also the recent advances in the field of ROS kinase inhibition, and the potential clinical applications of ROS kinase inhibitors.
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Affiliation(s)
- Ibrahim Mustafa El-Deeb
- Life/Health Division, Korea Institute of Science and Technology, Cheongryang, Seoul, Republic of Korea; Department of Biomolecular Science, University of Science and Technology, Yuseong-gu, Daejeon, Republic of Korea
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11
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Loreto C, Caltabiano R, Musumeci G, Caltabiano C, Greco MG, Leonardi R. Hepatocyte growth factor receptor, c-Met, in human embryo salivary glands. An immunohistochemical study. Anat Histol Embryol 2010; 39:173-7. [PMID: 20331593 DOI: 10.1111/j.1439-0264.2010.00991.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Salivary gland morphogenesis involves complex, coordinated events that include epithelial-mesenchymal interactions. Mesenchymal-epithelial transition factor (c-Met) is the hepatocyte growth factor (HGF) receptor. The latter is a hepatotropic factor originally identified in rat serum and platelets. It is essential in fetal tissue development, where it regulates complex morphogenetic processes including extracellular matrix invasion, cell migration, cell polarization and tubulogenesis. The c-Met/HGF system is believed to participate in epithelial-mesenchymal interactions during development. Twelve human embryonic minor salivary glands were studied by immunohistochemistry to investigate the role of c-Met in human salivary gland development. Strong c-Met immunopositivity in the glands demonstrated that the molecule is involved in their development and suggested a role for the c-Met/HGF system in this process.
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Affiliation(s)
- C Loreto
- Department of Anatomy, Diagnostic Pathology, Forensic Medicine, Hygiene and Public Health, University of Catania, 95123 Catania, Italy.
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Werz C, Köhler K, Hafen E, Stocker H. The Drosophila SH2B family adaptor Lnk acts in parallel to chico in the insulin signaling pathway. PLoS Genet 2009; 5:e1000596. [PMID: 19680438 PMCID: PMC2716533 DOI: 10.1371/journal.pgen.1000596] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Accepted: 07/13/2009] [Indexed: 12/27/2022] Open
Abstract
Insulin/insulin-like growth factor signaling (IIS) plays a pivotal role in the regulation of growth at the cellular and the organismal level during animal development. Flies with impaired IIS are developmentally delayed and small due to fewer and smaller cells. In the search for new growth-promoting genes, we identified mutations in the gene encoding Lnk, the single fly member of the SH2B family of adaptor molecules. Flies lacking lnk function are viable but severely reduced in size. Furthermore, lnk mutants display phenotypes reminiscent of reduced IIS, such as developmental delay, female sterility, and accumulation of lipids. Genetic epistasis analysis places lnk downstream of the insulin receptor (InR) and upstream of phosphoinositide 3-kinase (PI3K) in the IIS cascade, at the same level as chico (encoding the single fly insulin receptor substrate [IRS] homolog). Both chico and lnk mutant larvae display a similar reduction in IIS activity as judged by the localization of a PIP(3) reporter and the phosphorylation of protein kinase B (PKB). Furthermore, chico; lnk double mutants are synthetically lethal, suggesting that Chico and Lnk fulfill independent but partially redundant functions in the activation of PI3K upon InR stimulation.
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Affiliation(s)
- Christian Werz
- Institute of Molecular Systems Biology, Zurich, Switzerland
- PhD Program for Molecular Life Sciences, Life Science Zurich Graduate School, Zurich, Switzerland
| | - Katja Köhler
- Institute of Molecular Systems Biology, Zurich, Switzerland
| | - Ernst Hafen
- Institute of Molecular Systems Biology, Zurich, Switzerland
| | - Hugo Stocker
- Institute of Molecular Systems Biology, Zurich, Switzerland
- * E-mail:
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Hafen E, Basler K. Role of receptor tyrosine kinases during Drosophila development. CIBA FOUNDATION SYMPOSIUM 2007; 150:191-204; discussion 204-11. [PMID: 2164907 DOI: 10.1002/9780470513927.ch12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In vertebrates, a tyrosine kinase activity has been identified as an integral component of growth factor receptors and the products of proto-oncogenes. Many of these receptor tyrosine kinases (RTKs) appear to play a key role in the regulation of cell growth. Recent analyses of several Drosophila genes encoding putative RTKs indicate that this class of proteins also plays an important role in decisions about cell fate that depend on cellular interactions during development. The sevenless RTK mediates the position-dependent specification of a particular photoreceptor cell type (R7) in the eye. The local specification of R7 cells requires a functional tyrosine kinase domain of the sevenless protein but does not depend on the spatially restricted expression of the sevenless gene. The Drosophila EGF receptor homologue serves multiple functions during development, some of which are clearly unrelated to regulation of cell growth. Finally, the torso gene encodes an RTK required for the specification of the terminal regions of the Drosophila larva. A number of other genes have been genetically identified that appear to function in the same developmental processes upstream or downstream of these three RTKs. These loci are excellent candidates for genes encoding other components of the signalling pathways, such as ligands or substrates of the RTKs.
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Affiliation(s)
- E Hafen
- Zoological Institute, University of Zürich, Switzerland
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14
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Protein kinase D regulates several aspects of development in Drosophila melanogaster. BMC DEVELOPMENTAL BIOLOGY 2007; 7:74. [PMID: 17592635 PMCID: PMC1933421 DOI: 10.1186/1471-213x-7-74] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Accepted: 06/25/2007] [Indexed: 11/20/2022]
Abstract
Background Protein Kinase D (PKD) is an effector of diacylglycerol-regulated signaling pathways. Three isoforms are known in mammals that have been linked to diverse cellular functions including regulation of cell proliferation, differentiation, motility and secretory transport from the trans-Golgi network to the plasma membrane. In Drosophila, there is a single PKD orthologue, whose broad expression implicates a more general role in development. Results We have employed tissue specific overexpression of various PKD variants as well as tissue specific RNAi, in order to investigate the function of the PKD gene in Drosophila. Apart from a wild type (WT), a kinase dead (kd) and constitutively active (SE) Drosophila PKD variant, we also analyzed two human isoforms hPKD2 and hPKD3 for their capacity to substitute PKD activity in the fly. Overexpression of either WT or kd-PKD variants affected primarily wing vein development. However, overexpression of SE-PKD and PKD RNAi was deleterious. We observed tissue loss, wing defects and degeneration of the retina. The latter phenotype conforms to a role of PKD in the regulation of cytoskeletal dynamics. Strongest phenotypes were larval to pupal lethality. RNAi induced phenotypes could be rescued by a concurrent overexpression of Drosophila wild type PKD or either human isoform hPKD2 and hPKD3. Conclusion Our data confirm the hypothesis that Drosophila PKD is a multifunctional kinase involved in diverse processes such as regulation of the cytoskeleton, cell proliferation and death as well as differentiation of various fly tissues.
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15
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Doroquez DB, Rebay I. Signal integration during development: mechanisms of EGFR and Notch pathway function and cross-talk. Crit Rev Biochem Mol Biol 2007; 41:339-85. [PMID: 17092823 DOI: 10.1080/10409230600914344] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metazoan development relies on a highly regulated network of interactions between conserved signal transduction pathways to coordinate all aspects of cell fate specification, differentiation, and growth. In this review, we discuss the intricate interplay between the epidermal growth factor receptor (EGFR; Drosophila EGFR/DER) and the Notch signaling pathways as a paradigm for signal integration during development. First, we describe the current state of understanding of the molecular architecture of the EGFR and Notch signaling pathways that has resulted from synergistic studies in vertebrate, invertebrate, and cultured cell model systems. Then, focusing specifically on the Drosophila eye, we discuss how cooperative, sequential, and antagonistic relationships between these pathways mediate the spatially and temporally regulated processes that generate this sensory organ. The common themes underlying the coordination of the EGFR and Notch pathways appear to be broadly conserved and should, therefore, be directly applicable to elucidating mechanisms of information integration and signaling specificity in vertebrate systems.
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Affiliation(s)
- David B Doroquez
- Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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16
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Nairz K, Rottig C, Rintelen F, Zdobnov E, Moser M, Hafen E. Overgrowth caused by misexpression of a microRNA with dispensable wild-type function. Dev Biol 2006; 291:314-24. [PMID: 16443211 DOI: 10.1016/j.ydbio.2005.11.047] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 11/16/2005] [Indexed: 12/19/2022]
Abstract
MicroRNAs (miRNAs) represent an abundant class of non-coding RNAs that negatively regulate gene expression, primarily at the post-transcriptional level. miRNA genes are frequently located in proximity to fragile chromosomal sites associated with cancers and amplification of a miRNA cluster has been correlated with the etiology of lymphomas and solid tumors. The oncogenic potential of a miRNA polycistron has recently been demonstrated in vivo. Here, we show that misexpression of the Drosophila miRNA mirvana/mir-278 in the developing eye causes massive overgrowth, in part due to inhibition of apoptosis. A single base substitution affecting the mature miRNA blocks the gain-of-function phenotype but is not associated with a detectable reduction-of-function phenotype when homozygous. This result demonstrates that misexpressed miRNAs may acquire novel functions that cause unscheduled proliferation in vivo and thus exemplifies the potential of miRNAs to promote tumor formation.
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Affiliation(s)
- Knud Nairz
- Zoologisches Institut der Universität Zürich, Winterthurer Strasse 190, 8057 Zürich, Switzerland.
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17
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Fan Y, Soller M, Flister S, Hollmann M, Müller M, Bello B, Egger B, White K, Schäfer MA, Reichert H. The egghead gene is required for compartmentalization in Drosophila optic lobe development. Dev Biol 2005; 287:61-73. [PMID: 16182276 DOI: 10.1016/j.ydbio.2005.08.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Revised: 08/15/2005] [Accepted: 08/16/2005] [Indexed: 11/18/2022]
Abstract
The correct targeting of photoreceptor neurons (R-cells) in the developing Drosophila visual system requires multiple guidance systems in the eye-brain complex as well as the precise organization of the target area. Here, we report that the egghead (egh) gene, encoding a glycosyltransferase, is required for a compartment boundary between lamina glia and lobula cortex, which is necessary for appropriate R1-R6 innervation of the lamina. In the absence of egh, R1-R6 axons form a disorganized lamina plexus and some R1-R6 axons project abnormally to the medulla instead of the lamina. Mosaic analysis demonstrates that this is not due to a loss of egh function in the eye or in the neurons and glia of the lamina. Rather, as indicated by clonal analysis and cell-specific genetic rescue experiments, egh is required in cells of the lobula complex primordium which transiently abuts the lamina and medulla in the developing larval brain. In the absence of egh, perturbation of sheath-like glial processes occurs at the boundary region delimiting lamina glia and lobula cortex, and inappropriate invasion of lobula cortex cells across this boundary region disrupts the pattern of lamina glia resulting in inappropriate R1-R6 innervation. This finding underscores the importance of the lamina/lobula compartment boundary in R1-R6 axon targeting.
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Affiliation(s)
- Yun Fan
- Biozentrum/Pharmazentrum, University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland.
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18
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Wittwer F, Jaquenoud M, Brogiolo W, Zarske M, Wüstemann P, Fernandez R, Stocker H, Wymann MP, Hafen E. Susi, a negative regulator of Drosophila PI3-kinase. Dev Cell 2005; 8:817-27. [PMID: 15935772 DOI: 10.1016/j.devcel.2005.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 04/06/2005] [Accepted: 04/12/2005] [Indexed: 12/22/2022]
Abstract
The Phosphatidylinositol-3 kinase/Protein Kinase B (PI3K/PKB) signaling pathway controls growth, metabolism, and lifespan in animals, and deregulation of its activity is associated with diabetes and cancer in humans. Here, we describe Susi, a coiled-coil domain protein that acts as a negative regulator of insulin signaling in Drosophila. Whereas loss of Susi function increases body size, overexpression of Susi reduces growth. We provide genetic evidence that Susi negatively regulates dPI3K activity. Susi directly binds to dP60, the regulatory subunit of dPI3K. Since Susi has no overt similarity to known inhibitors of PI3K/PKB signaling, it defines a novel mechanism by which this signaling cascade is kept in check. The fact that Susi is expressed in a circadian rhythm, with highest levels during the night, suggests that Susi attenuates insulin signaling during the fasting period.
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Affiliation(s)
- Franz Wittwer
- Zoologisches Institut, Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
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19
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Claeys I, Poels J, Simonet G, Franssens V, Van Loy T, Van Hiel MB, Breugelmans B, Vanden Broeck J. Insect Neuropeptide and Peptide Hormone Receptors: Current Knowledge and Future Directions. VITAMINS & HORMONES 2005; 73:217-82. [PMID: 16399412 DOI: 10.1016/s0083-6729(05)73007-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Peptides form a very versatile class of extracellular messenger molecules that function as chemical communication signals between the cells of an organism. Molecular diversity is created at different levels of the peptide synthesis scheme. Peptide messengers exert their biological functions via specific signal-transducing membrane receptors. The evolutionary origin of several peptide precursor and receptor gene families precedes the divergence of the important animal Phyla. In this chapter, current knowledge is reviewed with respect to the analysis of peptide receptors from insects, incorporating many recent data that result from the sequencing of different insect genomes. Therefore, detailed information is provided on six different peptide receptor families belonging to two distinct receptor categories (i.e., the heptahelical and the single transmembrane receptors). In addition, the remaining problems, the emerging concepts, and the future prospects in this area of research are discussed.
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MESH Headings
- Animals
- Drosophila/genetics
- Drosophila/physiology
- Drosophila Proteins/genetics
- Drosophila Proteins/physiology
- Forecasting
- Frizzled Receptors/genetics
- Frizzled Receptors/physiology
- Insecta/genetics
- Insecta/physiology
- Invertebrate Hormones/genetics
- Invertebrate Hormones/physiology
- Receptor Protein-Tyrosine Kinases/physiology
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/physiology
- Receptors, Guanylate Cyclase-Coupled/genetics
- Receptors, Guanylate Cyclase-Coupled/physiology
- Receptors, Invertebrate Peptide/genetics
- Receptors, Invertebrate Peptide/physiology
- Receptors, Peptide/genetics
- Receptors, Peptide/physiology
- Receptors, Tachykinin/genetics
- Receptors, Tachykinin/physiology
- Receptors, Transforming Growth Factor beta/physiology
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Affiliation(s)
- Ilse Claeys
- Laboratory for Developmental Physiology, Genomics and Proteomics Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
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20
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Chen YM, Lee NPY, Mruk DD, Lee WM, Cheng CY. Fer kinase/FerT and adherens junction dynamics in the testis: an in vitro and in vivo study. Biol Reprod 2003; 69:656-72. [PMID: 12700184 DOI: 10.1095/biolreprod.103.016881] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fer kinase is a 94-kDa cytoplasmic cell-cell actin-based adherens junction (AJ)-associated nonreceptor protein tyrosine kinase (PTK) found in multiple epithelia including the testis, whereas FerT kinase (51 kDa) is the truncated testis-specific form of Fer kinase, lacking the Fps/Fes/Fer/CIP4 (products of oncogenes identified in avian and feline sarcoma, encoding tyrosine protein kinases) and the three coiled-coil domains versus Fer kinase. Yet the role(s) of Fer kinase in AJ dynamics in the testis remains largely unexplored. We have used an in vitro model of AJ assembly with Sertoli-germ cell cocultures and an in vivo model of AJ disassembly in which adult rats were treated with 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364) to study changes in the expression and/or localization of Fer kinase during AJ restructuring. Fer kinase/FerT was expressed by Sertoli and germ cells when cultured in vitro. Using an antibody prepared against a synthetic peptide, NH2-SAPQNCPEEIFTIMMKCWDYK-COOH, corresponding to residues 779-799 of Fer kinase in the rat, which failed to cross-react with FerT kinase, for immunohistochemistry, Fer kinase was detected in the seminiferous epithelium in virtually all stages of the epithelial cycle. At stages XIII-VI, Fer kinase was associated largely with round and elongating spermatids. At stages VII-VIII, Fer kinase associated almost exclusively with round spermatids with very weak staining associated with elongated spermatids. This stage-specific localization of Fer kinase in the epithelium was confirmed by using staged tubules for semiquantitative reverse transcription-polymerase chain reaction. Studies by immunoprecipitation revealed that Fer kinase associated with N-cadherin, gamma-catenin, p120ctn, c-Src (a putative PTK and the product of the transforming, sarcoma-inducing gene of Rous sarcoma virus), Rab 8 (a GTPase), actin, vimentin, but not E-cadherin, afadin, nectin-3, and integrin beta1, suggesting Fer kinase associates not only with the actin-based cell-cell AJ structures, such as the N-cadherin/catenin complex (but not the alpha6beta1 integrin/laminin and the afadin/nectin complex), but also with intermediate filament-based cell-cell desmosomes. An induction in Fer kinase expression was detected during Sertoli-germ cell AJ assembly in vitro but not during AF-2364-induced AJ disruption in vivo. Yet this AF-2364-induced Fer kinase plummeting associated with an induction in N-cadherin, beta-catenin, and p120ctn, particularly at the base of the seminiferous epithelium. In summary, Fer kinase structurally associates with the N-cadherin/catenin protein complex in the testis and can possibly be used to mediate signaling function via the cadherin/catenin protein complex.
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21
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Schreiber SL, Preiss A, Nagel AC, Wech I, Maier D. Genetic screen for modifiers of the rough eye phenotype resulting from overexpression of the Notch antagonist hairless in Drosophila. Genesis 2002; 33:141-52. [PMID: 12124948 DOI: 10.1002/gene.10102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hairless was identified as antagonist in the Notch signaling pathway based on genetic interactions. Molecularly, Hairless inhibits Notch target gene activation by directly binding to the Notch signal transducer Su(H). Additional functional domains apart from the Su(H) binding domain, however, suggest additional roles for the Hairless protein. To further our understanding of Hairless functions, we have performed a genetic screen for modifiers of a rough eye phenotype caused by overexpression of Hairless during eye development. A number of enhancers were identified that comprise mutations in components of Notch- and EGFR-signaling pathways, some unknown genes and the gene rugose. Mutant alleles of rugose display manifold genetic interactions with mutants in Notch and EGFR signaling pathway components. Accordingly, the rugose eye phenotype is rescued by Hairless and enhanced by Delta. Molecularly, interactions might occur at the protein level because rugose appears not to be a direct transcriptional target of Notch.
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22
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Hofmann WK, Jones LC, Lemp NA, de Vos S, Gschaidmeier H, Hoelzer D, Ottmann OG, Koeffler HP. Ph(+) acute lymphoblastic leukemia resistant to the tyrosine kinase inhibitor STI571 has a unique BCR-ABL gene mutation. Blood 2002; 99:1860-2. [PMID: 11861307 DOI: 10.1182/blood.v99.5.1860] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tyrosine kinase inhibitor STI571 is a promising agent for the treatment of advanced Philadelphia chromosome positive (Ph(+)) acute lymphoblastic leukemia (ALL), but resistance develops rapidly in most patients after an initial response. To identify mechanisms of resistance to STI571, 30 complementary DNAs (including 9 matched samples) obtained from the bone marrow of individuals with Ph(+) ALL were analyzed by direct sequencing of a 714-base pair region of ABL encoding for the adenosine triphosphate (ATP)-binding site and the kinase activation loop. A single point mutation was found at nucleotide 1127 (GI6382056) resulting in Glu255Lys. This mutation occurred in 6 of 9 patients (67%) following their treatment with STI571 but not in the samples from patients before beginning treatment with STI571. Glu255Lys is within the motif important for forming the pocket of the ATP-binding site in ABL and it is highly conserved across species. In conclusion, Ph(+) ALL samples resistant to STI571 have a unique mutation Glu255Lys of BCR-ABL.
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Affiliation(s)
- Wolf-K Hofmann
- Division of Hematology/Oncology, Cedars Sinai Research Institute, UCLA School of Medicine, Los Angeles, California 90048, USA.
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23
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Rintelen F, Stocker H, Thomas G, Hafen E. PDK1 regulates growth through Akt and S6K in Drosophila. Proc Natl Acad Sci U S A 2001; 98:15020-5. [PMID: 11752451 PMCID: PMC64976 DOI: 10.1073/pnas.011318098] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The insulin/insulin-like growth factor-1 signaling pathway promotes growth in invertebrates and vertebrates by increasing the levels of phosphatidylinositol 3,4,5-triphosphate through the activation of p110 phosphatidylinositol 3-kinase. Two key effectors of this pathway are the phosphoinositide-dependent protein kinase 1 (PDK1) and Akt/PKB. Although genetic analysis in Caenorhabditis elegans has implicated Akt as the only relevant PDK1 substrate, cell culture studies have suggested that PDK1 has additional targets. Here we show that, in Drosophila, dPDK1 controls cellular and organism growth by activating dAkt and S6 kinase, dS6K. Furthermore, dPDK1 genetically interacts with dRSK but not with dPKN, encoding two substrates of PDK1 in vitro. Thus, the results suggest that dPDK1 is required for dRSK but not dPKN activation and that it regulates insulin-mediated growth through two main effector branches, dAkt and dS6K.
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Affiliation(s)
- F Rintelen
- Zoologisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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24
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Morey M, Serras F, Baguñà J, Hafen E, Corominas M. Modulation of the Ras/MAPK signalling pathway by the redox function of selenoproteins in Drosophila melanogaster. Dev Biol 2001; 238:145-56. [PMID: 11784000 DOI: 10.1006/dbio.2001.0389] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Modulation of reactive oxygen species (ROS) plays a key role in signal transduction pathways. Selenoproteins act controlling the redox balance of the cell. We have studied how the alteration of the redox balance caused by patufet (selD(ptuf)), a null mutation in the Drosophila melanogaster selenophosphate synthetase 1 (sps1) gene, which codes for the SelD enzyme of the selenoprotein biosynthesis, affects the Ras/MAPK signalling pathway. The selD(ptuf) mutation dominantly suppresses the phenotypes in the eye and the wing caused by hyperactivation of the Ras/MAPK cassette and the activated forms of the Drosophila EGF receptor (DER) and Sevenless (Sev) receptor tyrosine kinases (RTKs), which signal in the eye and wing, respectively. No dominant interaction is observed with sensitized conditions in the Wnt, Notch, Insulin-Pi3K, and DPP signalling pathways. Our current hypothesis is that selenoproteins selectively modulate the Ras/MAPK signalling pathway through their antioxidant function. This is further supported by the fact that a selenoprotein-independent increase in ROS caused by the catalase amorphic Cat(n1) allele also reduces Ras/MAPK signalling. Here, we present the first evidence for the role of intracellular redox environment in signalling pathways in Drosophila as a whole organism.
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Affiliation(s)
- M Morey
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, Barcelona, 08028, Spain
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25
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Manseau LJ. RNA localization meets wingless signaling. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2001; 2001:pe1. [PMID: 11752665 DOI: 10.1126/stke.2001.92.pe1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In many tissues in many organisms, messenger RNA (mRNA) is not randomly distributed throughout a cell, but is targeted and accumulated in specific subcellular locations. Signal transduction pathways can be extremely sensitive to gradients of signaling proteins and represent a cellular phenomenon where RNA localization may be important. Manseau discusses how targeting of the RNA for a secreted ligand, Wingless (Wg), is important in promoting proper Wg signaling in early Drosophila embryos and the mechanism for achieving this subcellular targeting. The possible mechanistic models for how restricted wg mRNA distribution influences Wg signaling are also detailed.
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Affiliation(s)
- L J Manseau
- Department of Molecular and Cellular Biology, Interdisciplinary Program in Genetics, University of Arizona, Tucson, AZ 85721, USA.
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26
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Manseau LJ. RNA Localization Meets Wingless Signaling. Sci Signal 2001. [DOI: 10.1126/scisignal.922001pe1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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27
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Ciapponi L, Jackson DB, Mlodzik M, Bohmann D. Drosophila Fos mediates ERK and JNK signals via distinct phosphorylation sites. Genes Dev 2001; 15:1540-53. [PMID: 11410534 PMCID: PMC312716 DOI: 10.1101/gad.886301] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2001] [Accepted: 04/17/2001] [Indexed: 11/25/2022]
Abstract
During Drosophila development Fos acts downstream from the JNK pathway. Here we show that it can also mediate ERK signaling in wing vein formation and photoreceptor differentiation. Drosophila JNK and ERK phosphorylate D-Fos with overlapping, but distinct, patterns. Analysis of flies expressing phosphorylation site point mutants of D-Fos revealed that the transcription factor responds differentially to JNK and ERK signals. Mutations in the phosphorylation sites for JNK interfere specifically with the biological effects of JNK activation, whereas mutations in ERK phosphorylation sites affect responses to the EGF receptor-Ras-ERK pathway. These results indicate that the distinction between ERK and JNK signals can be made at the level of D-Fos, and that different pathway-specific phosphorylated forms of the protein can elicit different responses.
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Affiliation(s)
- L Ciapponi
- European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
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28
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Halfar K, Rommel C, Stocker H, Hafen E. Ras controls growth, survival and differentiation in the Drosophila eye by different thresholds of MAP kinase activity. Development 2001; 128:1687-96. [PMID: 11290305 DOI: 10.1242/dev.128.9.1687] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ras mediates a plethora of cellular functions during development. In the developing eye of Drosophila, Ras performs three temporally separate functions. In dividing cells, it is required for growth but is not essential for cell cycle progression. In postmitotic cells, it promotes survival and subsequent differentiation of ommatidial cells. In the present paper, we have analyzed the different roles of Ras during eye development by using molecularly defined complete and partial loss-of-function mutations of Ras. We show that the three different functions of Ras are mediated by distinct thresholds of MAPK activity. Low MAPK activity prolongs cell survival and permits differentiation of R8 photoreceptor cells while high or persistent MAPK activity is sufficient to precociously induce R1-R7 photoreceptor differentiation in dividing cells.
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Affiliation(s)
- K Halfar
- Zoologisches Institut, Universität Zürich, Winterthurerstrasse 190, Switzerland
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29
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Wittwer F, van der Straten A, Keleman K, Dickson BJ, Hafen E. Lilliputian: an AF4/FMR2-related protein that controls cell identity and cell growth. Development 2001; 128:791-800. [PMID: 11171403 DOI: 10.1242/dev.128.5.791] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Members of the AF4/FMR2 family of nuclear proteins are involved in human diseases such as acute lymphoblastic leukemia and mental retardation. Here we report the identification and characterization of the Drosophila lilliputian (lilli) gene, which encodes a nuclear protein related to mammalian AF4 and FMR2. Mutations in lilli suppress excessive neuronal differentiation in response to a constitutively active form of Raf in the eye. In the wild type, Lilli has a partially redundant function in the Ras/MAPK pathway in differentiation but it is essential for normal growth. Loss of Lilli function causes an autonomous reduction in cell size and partially suppresses the increased growth associated with loss of PTEN function. These results suggest that Lilli acts in parallel with the Ras/MAPK and the PI3K/PKB pathways in the control of cell identity and cellular growth.
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Affiliation(s)
- F Wittwer
- Zoologisches Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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30
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Affiliation(s)
- J P Kumar
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322-3030, USA
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31
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Yeh E, Zhou L, Rudzik N, Boulianne GL. Neuralized functions cell autonomously to regulate Drosophila sense organ development. EMBO J 2000; 19:4827-37. [PMID: 10970873 PMCID: PMC302081 DOI: 10.1093/emboj/19.17.4827] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2000] [Revised: 07/19/2000] [Accepted: 07/19/2000] [Indexed: 11/13/2022] Open
Abstract
Neurogenic genes, including Notch and Delta, are thought to play important roles in regulating cell-cell interactions required for Drosophila sense organ development. To define the requirement of the neurogenic gene neuralized (neu) in this process, two independent neu alleles were used to generate mutant clones. We find that neu is required for determination of cell fates within the proneural cluster and that cells mutant for neu autonomously adopt neural fates when adjacent to wild-type cells. Furthermore, neu is required within the sense organ lineage to determine the fates of daughter cells and accessory cells. To gain insight into the mechanism by which neu functions, we used the GAL4/UAS system to express wild-type and epitope-tagged neu constructs. We show that Neu protein is localized primarily at the plasma membrane. We propose that the function of neu in sense organ development is to affect the ability of cells to receive Notch-Delta signals and thus modulate neurogenic activity that allows for the specification of non-neuronal cell fates in the sense organ.
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Affiliation(s)
- E Yeh
- Program in Developmental Biology, The Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada
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32
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Abstract
Two former biologists play at dice. In the center of the table there are several banknotes from a prize they had won a few years before they dropped out of science. The rule of the game is that each player gets a banknote whenever he correctly predicts how many throws it will take after throwing a 6 to throw the next 6. One of the two players, a former theoretical biologist, remembers that the frequency of throwing a 6 is one in six, so he always foretells that the waiting period will be 6. The other player's cause for failing in science was opposite: he believed in superstitions. As his lucky number is three, he guesses after each 6 that the next 6 will occur three throws later. Which of the two fellows will recover more from the prize money? And is there a waiting period that could be predicted that would make more money?
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Affiliation(s)
- K Basler
- Institut für Molekularbiologie, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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33
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Böhni R, Riesgo-Escovar J, Oldham S, Brogiolo W, Stocker H, Andruss BF, Beckingham K, Hafen E. Autonomous control of cell and organ size by CHICO, a Drosophila homolog of vertebrate IRS1-4. Cell 1999; 97:865-75. [PMID: 10399915 DOI: 10.1016/s0092-8674(00)80799-0] [Citation(s) in RCA: 637] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The control of growth is fundamental to the developing metazoan. Here, we show that CHICO, a Drosophila homolog of vertebrate IRS1-4, plays an essential role in the control of cell size and growth. Animals mutant for chico are less than half the size of wild-type flies, owing to fewer and smaller cells. In mosaic animals, chico homozygous cells grow slower than their heterozygous siblings, show an autonomous reduction in cell size, and form organs of reduced size. Although chico flies are smaller, they show an almost 2-fold increase in lipid levels. The similarities of the growth defects caused by mutations in chico and the insulin receptor gene in Drosophila and by perturbations of the insulin/IGF1 signaling pathway in vertebrates suggest that this pathway plays a conserved role in the regulation of overall growth by controling cell size, cell number, and metabolism.
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Affiliation(s)
- R Böhni
- Zoologisches Institut, Universität Zürich, Switzerland
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34
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Sevrioukov EA, Walenta JH, Sunio A, Phistry M, Krämer H. Oligomerization of the extracellular domain of Boss enhances its binding to the Sevenless receptor and its antagonistic effect on R7 induction. J Cell Sci 1998; 111 ( Pt 6):737-47. [PMID: 9472002 DOI: 10.1242/jcs.111.6.737] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the developing compound eye of Drosophila, neuronal differentiation of the R7 photoreceptor cell is induced by the interaction of the receptor tyrosine kinase Sevenless with its ligand Bride of sevenless (Boss), which is expressed on the neighboring R8 cell. Boss is an unusual ligand of a receptor tyrosine kinase: it is composed of a large extracellular domain, a transmembrane domain with seven membrane-spanning segments and a cytoplasmic tail. Expression of a monomeric, secreted form of the extracellular domain of Boss is not sufficient for Sevenless activation, and instead acts as a weak antagonist. Because oligomerization appears to be a critical step in the activation of receptor tyrosine kinases, we used oligomerized forms of the Boss extracellular domain to test their ability to bind to Sevenless in vivo and restore R7 induction in vivo. Oligomerization was achieved by fusion to the leucine zipper of the yeast transcription factor GCN4 or to the tetramerization helix of Lac repressor. Binding of these multivalent proteins to Sevenless could be detected in vitro by immunoprecipitation of cross-linked ligand/receptor complexes and in vivo by receptor-dependent ligand localization. However, neither R8-specific or ubiquitous expression of multivalent Exboss ligands rescued the boss phenotype. Instead, these ligands acted as competitive inhibitors for wild-type Boss protein and thereby suppressed R7 induction. Therefore the role of the transmembrane or cytoplasmic domains of Boss in the activation of the Sev receptor cannot be replaced by oligomerization.
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Affiliation(s)
- E A Sevrioukov
- Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallasp65235-9111, USA
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35
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Raabe T. Genetic analysis of sevenless tyrosine kinase signaling in Drosophila. Curr Top Microbiol Immunol 1997; 228:343-61. [PMID: 9401212 DOI: 10.1007/978-3-642-80481-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- T Raabe
- Theodor Boveri Institut für Biowissenschaften, Lehrstuhl für Genetik, Universität Würzburg, Germany
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36
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Bisgrove BW, Raible DW, Walter V, Eisen JS, Grunwald DJ. Expression ofc-ret in the zebrafish embryo: Potential roles in motoneuronal development. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/(sici)1097-4695(19971120)33:6<749::aid-neu4>3.0.co;2-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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37
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Abstract
Mammalian nephrogenesis constitutes a series of complex developmental processes in which there is a differentiation and rapid proliferation of pluripotent cells leading to the formation of a defined sculpted tissue mass, and this is followed by a continuum of cell replication and terminal differentiation. Metanephrogenesis ensues with the intercalation of epithelial ureteric bud into loosely organized metanephric mesenchyme. Such an interaction is reciprocal, such that the intercalating ureteric bud induces the conversion of metanephric mesenchyme into an epithelial phenotype, while the mesenchyme stimulates the iterations of the ureteric bud. The induced mesenchyme then undergoes a series of developmental stages to form a mature glomerulus and tubular segments of the kidney. Coincidental with the formation of these nephric elements, the developing kidney is vascularized by the process of vasculogenesis and angiogenesis. Thus, the process of metanephric development is quite complex, and it involves a diverse group of molecules who's biological activities are inter-linked with one another and they regulate, in a concerted manner, the differentiation and maturation of the mammalian kidney. This diverse group of molecules include extracellular matrix (ECM) proteins and their receptors, ECM-degrading enzymes and their inhibitors, growth factors and their receptors, proto-oncogenes and transcription factors. A large body of literature data are available, which suggest a critical role of these molecules in metanephric development, and this review summarizes the recent developments that relate to metanephrogenesis.
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Affiliation(s)
- E I Wallner
- Department of Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA
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38
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Rommel C, Radziwill G, Moelling K, Hafen E. Negative regulation of Raf activity by binding of 14-3-3 to the amino terminus of Raf in vivo. Mech Dev 1997; 64:95-104. [PMID: 9232600 DOI: 10.1016/s0925-4773(97)00052-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In the developing eye of Drosophila the protein kinase D-Raf controls the specification of the R7 photoreceptor cells. We show that overexpression of wild-type D-Raf inhibits the formation of R7 cells in a dose-dependent manner. Conversely, overexpression of mutant D-Raf proteins in which the conserved S388 is replaced by A or by D promotes the formation of supernumerary R7 cells, indicating increased D-Raf activity in vivo. S388 in D-Raf corresponds to S259 in c-Raf; shown to be involved in binding of 14-3-3. We show that analogous substitutions of S259 in c-Raf prevent binding of 14-3-3 zeta to the amino terminus of c-Raf and cause a Ras-independent constitutively increased c-Raf kinase activity. Binding of 14-3-3 zeta to the second binding site at the carboxy terminal catalytic domain was unaffected by these mutations. These results suggest that the increased kinase activity of mutant D-Raf is caused by the selective loss of 14-3-3 binding to its amino terminus. Therefore, binding of 14-3-3 to the amino terminus of Raf appears to negatively regulate Raf kinase activity in vivo.
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Affiliation(s)
- C Rommel
- Institute of Medical Virology, University of Zuerich, Switzerland
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39
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Saxena SP, Fan T, Li M, Israels ED, Israels LG. A novel role for vitamin K1 in a tyrosine phosphorylation cascade during chick embryogenesis. J Clin Invest 1997; 99:602-7. [PMID: 9045861 PMCID: PMC507841 DOI: 10.1172/jci119202] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The development of the embryo is dependent upon a highly coordinated repertoire of cell division, differentiation, and migration. Protein-tyrosine phosphorylation plays a pivotal role in the regulation of these processes. Vitamin K-dependent gamma-carboxylated proteins have been identified as ligands for a unique family (Tyro 3 and 7) of receptor tyrosine kinases (RTKs) with transforming ability. The involvement of vitamin K metabolism and function in two well characterized birth defects, warfarin embryopathy and vitamin K epoxide reductase deficiency, suggests that developmental signals from K-dependent pathways may be required for normal embryogenesis. Using a chick embryogenesis model, we now demonstrate the existence of a vitamin K1-dependent protein-tyrosine phosphorylation cascade involving c-Eyk, a member of the Tyro 12 family, and key intracellular proteins, including focal adhesion kinase (pp125FAK), paxillin, and pp60src. This cascade is sensitive to alteration in levels or metabolism of vitamin K1. These findings provide a major clue as to why, in the mammalian (and human) fetus, the K-dependent proteins are maintained in an undercarboxylated state, even to the point of placing the newborn at hemorrhagic risk. The precise regulation of vitamin K1-dependent regulatory pathways would appear to be critical for orderly embryogenesis.
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Affiliation(s)
- S P Saxena
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada.
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40
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Chou WH, Hall KJ, Wilson DB, Wideman CL, Townson SM, Chadwell LV, Britt SG. Identification of a novel Drosophila opsin reveals specific patterning of the R7 and R8 photoreceptor cells. Neuron 1996; 17:1101-15. [PMID: 8982159 DOI: 10.1016/s0896-6273(00)80243-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The function of the compound eye is dependent upon a developmental program that specifies different cell fates and directs the expression of spectrally distinct opsins in different photoreceptor cells. Rh5 is a novel Drosophila opsin gene that encodes a biologically active visual pigment that is expressed in a subset of R8 photoreceptor cells. Rh5 expression in the R8 cell of an individual ommatidium is strictly coordinated with the expression of Rh3, in the overlying R7 cell. In sevenless mutant files, which lack R7 photoreceptor cells, the expression of the Rh5 protein in R8 cells is disrupted, providing evidence for a specific developmental signal between the R7 and R8 cells that is responsible for the paired expression of opsin genes.
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Affiliation(s)
- W H Chou
- Institute of Biotechnology, University of Texas Health Science Center, San Antonio 78245
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41
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42
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Bohmann D, Ellis MC, Staszewski LM, Mlodzik M. Drosophila Jun mediates Ras-dependent photoreceptor determination. Cell 1994; 78:973-86. [PMID: 7923366 DOI: 10.1016/0092-8674(94)90273-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The expression of the D. melanogaster transcription factor Jun in the eye imaginal disc correlates temporally and spatially with the determination of neuronal photoreceptor fate. Expression of dominant negative forms of Jun in photoreceptor precursor cells results in dose-dependent loss of photoreceptors in the adult fly. Conversely, localized overexpression of Jun in the eye imaginal disc can induce the differentiation of additional photoreceptor cells. Furthermore, the transformation of nonneuronal cone cells into R7 neurons elicited by constitutively active forms of sevenless, Ras1, Raf, and MAP kinase is relieved in the presence of Jun mutants. These results demonstrate a requirement of Jun downstream of the sevenless/ras signaling pathway for neuronal development in the Drosophila eye.
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Affiliation(s)
- D Bohmann
- European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany
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43
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Yun B, Farkas R, Lee K, Rabinow L. The Doa locus encodes a member of a new protein kinase family and is essential for eye and embryonic development in Drosophila melanogaster. Genes Dev 1994; 8:1160-73. [PMID: 7926721 DOI: 10.1101/gad.8.10.1160] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mutations at the Darkener of apricot (Doa) locus of Drosophila cause roughened eyes and increase transcript accumulation from the retrotransposon copia up to fourfold. Cloning of the gene and sequencing of cDNAs reveals that it encodes a putative serine/threonine protein kinase. Sequence data base searches identify it is a member of a novel highly conserved protein kinase family, with homologs in humans, mice, and Saccharomyces cerevisiae, not related to each other previously. Family members are characterized by a peptide motif reading EHLAMMERILG at kinase subdomain X, which is virtually 100% identical in all homologs. We therefore refer to this new family as the LAMMER protein kinases. As predicted from its primary sequence, Doa protein possess intrinsic protein kinase activity when expressed in bacteria, as assayed via autophosphorylation. The gene is expressed throughout development, and both stage and tissue-specific RNAs are found. Its function is essential, because maternally deposited or zygotically transcribed mRNA is required for development to larval stages, and defects in segmentation and development of the nervous system are observed in embryos derived from heteroallelic mothers. Doa function is also critical to Drosophila eye development, because the organization and development of pigment cells, bristles, and photoreceptors are affected in various mutant classes. In the most extreme cases that survive to adulthood, retinal photoreceptors degenerate prior to eclosion. These results demonstrate that the kinase encoded by Doa is required at multiple stages of development, for both differentiation and maintenance of specific cell types.
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Affiliation(s)
- B Yun
- Waksman Institute, Rutgers University, Piscataway, New Jersey 08855-0759
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44
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Pelsue S, Agris PF. Immunoreactivity between a monoclonal lupus autoantibody and the arginine/aspartic acid repeats within the U1-snRNP 70K autoantigen is conformationally restricted. JOURNAL OF PROTEIN CHEMISTRY 1994; 13:401-8. [PMID: 7527219 DOI: 10.1007/bf01901696] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Immunoreactivity of the arginine/aspartic acid (RD) repeats of the 70K protein of U1 small nuclear ribonucleoprotein (snRNP) was determined to be conformationally dependent. The monoclonal autoantibody 2.73, isolated from a lupus-prone MRL/n mouse model, is reactive with the RD repeat regions of U1 snRNP 70K protein. Immunochemical analysis of the antigenic determinants with use of chemically synthesized peptides characterized the 2.73 epitope as the RD repeat [Pelsue, S., et al. (1993) Autoimmunity, 15, 231-236] Analysis by circular dichroism (CD) and nuclear magnetic resonance spectroscopy indicates conformational preferences in the immunoreactive peptides. Computer analyses of CD spectra obtained on the RD-containing peptides predict beta-turns and beta-sheet to be the preferred conformations of the RD repeats. This structure was also predicted by the Chou-Fasman algorithm. The RD repeat is believed to be a conserved structural motif; however, the biological function is still unclear. Immunological and biochemical analysis of autoimmune antibodies and their respective antigenic determinants has helped to characterize the possible mechanisms that lead to autoimmune diseases. This is the first report of a conformationally dependent, linear epitope of an autoantibody.
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Affiliation(s)
- S Pelsue
- Department of Biochemistry, North Carolina State University, Raleigh 27695-7622
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45
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Ruiz JC, Robertson EJ. The expression of the receptor-protein tyrosine kinase gene, eck, is highly restricted during early mouse development. Mech Dev 1994; 46:87-100. [PMID: 7918100 DOI: 10.1016/0925-4773(94)90078-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cell-cell interactions during embryogenesis have been shown to be important for establishing developmental fates in a number of organisms such as Drosophila and Caenorhabditis. One class of genes shown to mediate this process are receptor-protein tyrosine kinases (R-PTKs). To examine whether R-PTKs might participate in similar mechanisms operating in the mammalian embryo, an important prerequisite is to show that these genes are expressed in spatial and temporal patterns consistent with such a role. Here, we analyze the expression of eck, a member of the eph family of R-PTKs, during gastrulation and early organogenesis by in situ hybridization. eck transcripts are first detected in gastrulation stage embryos (6.5-7.5 days post coitum (dpc)) in ectodermal cells adjacent to the distal region of the primitive streak. By the neural plate stage (approximately 7.5 dpc), eck expression becomes restricted to the extreme distal end or node of the primitive streak. After the beginning of somitogenesis (approximately 8.0 dpc), eck expression persists in the node as this structure regresses toward the caudal end of the embryo. In addition, beginning at the mid head fold stage (approximately 7.75 dpc), we observe that eck exhibits a dynamic and spatially restricted expression pattern in the prospective hindbrain region. eck transcripts are initially detected in a 5-cell wide strip of mesodermal cells underlying prospective rhombomere 4 (r4). Subsequently at the beginning of somitogenesis, eck mRNA expression is observed in prospective r4. At the 4--8-somite stage, eck transcripts are observed in r4, mesenchymal cells underlying r4, and surface ectoderm in the vicinity of the developing second branchial arch. By the 10-somite stage, eck mRNA expression in these cells is downregulated. Additionally, at the 5--8-somite stage, eck transcripts are detected initially in the lateral mesenchyme immediately underlying the surface ectoderm adjacent to r5 and r6, and subsequently in surface ectoderm overlying the developing third branchial arch. These data suggest that eck may be involved in cell-cell interactions guiding early hindbrain development.
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Affiliation(s)
- J C Ruiz
- Department of Biochemistry, Molecular Biology, and Cellular and Developmental Biology, Harvard University, Cambridge, MA 02138
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46
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Yamamoto D. Signaling mechanisms in induction of the R7 photoreceptor in the developing Drosophila retina. Bioessays 1994; 16:237-44. [PMID: 8031300 DOI: 10.1002/bies.950160406] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Drosophila compound eye is an excellent experimental system for analysing fate induction of identifiable single cells. Each ommatidium, a unit eye, contains eight photoreceptors (R1-R8), and the differentiation of these photoreceptors occurs in the larval eye imaginal disc in discrete steps: first R8 is determined, then R2/R5, R3/R4, R1/R6 and finally R7. Induction of R7, in particular, has been extensively studied at the molecular level. The R8 photoreceptor presents on its surface a ligand, Bride of Sevenless, that binds and activates Sevenless receptor tyrosine kinase in the R7 precursor. Autophosphorylated Sevenless initiates a Ras1-mediated cascade, which eventually activates transcription factors in the nucleus via Raf1 and MAP kinases, resulting in R7 development. However, recent studies indicate that Sevenless (Sev) functions just to neuralize the cell and has no role in R7 fate determination per se. It appears that the R7 fate may represent the lowest rung of a 'neuronal ground state', which is attained without any specific inductive cue. It is plausible that the R7 precursor is actively prevented from taking on the neuronal fate and this inhibition is removed by activation of Sev.
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Affiliation(s)
- D Yamamoto
- Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan
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47
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Affiliation(s)
- L Wiesmüller
- Heinrich-Pette-Institut für exp. Virologie und Immunologie, Universität Hamburg, F.R.G
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48
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Diaz-Benjumea FJ, Hafen E. The sevenless signalling cassette mediates Drosophila EGF receptor function during epidermal development. Development 1994; 120:569-78. [PMID: 8162856 DOI: 10.1242/dev.120.3.569] [Citation(s) in RCA: 141] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Drosophila, Drk, an SH2 adaptor protein, Sos, a putative activator of Ras1, Ras1, raf and rolled/MAP kinase have been shown to be required for signalling from the sevenless and the torso receptor tyrosine kinase. From these studies, it was unclear whether these components act in a single linear pathway as suggested by the genetic analysis or whether different components serve to integrate different signals. We have analyzed the effects of removing each of these components during the development of the adult epidermal structures by generating clones of homozygous mutant cells in a heterozygous background. Mutations in each of these signalling components produce a very similar set of phenotypes. These phenotypes resemble those caused by loss-of-function mutations in the Drosophila EGF receptor homolog (DER). It appears that these components form a signalling cassette, which mediates all aspects of DER signalling but that is not required for other signalling processes during epidermal development.
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49
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Abstract
Receptor tyrosine kinases regulate a number of different cell fate decisions during invertebrate development. Genetic analysis of the signal transduction pathways activated by these kinases suggests that they converge upon a common pathway involving Ras and a cascade of cytoplasmic kinases, diverging again in the nucleus with the regulation of specific transcription factors.
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Affiliation(s)
- B Dickson
- Zoologisches Institut, Universität Zürich, Switzerland
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50
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Hafen E, Dickson B, Brunner D, Raabe T. Genetic dissection of signal transduction mediated by the sevenless receptor tyrosine kinase in Drosophila. Prog Neurobiol 1994; 42:287-92. [PMID: 8008827 DOI: 10.1016/0301-0082(94)90067-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The specification of the R7 photoreceptor cell fate in the developing eye of Drosophila depends on the local activation of the sevenless (sev) receptor tyrosine kinase by boss, a protein expressed on the membrane of the neighboring R8 cell. Constitutive activation of the sev receptor results in a dosage dependent increase in the number of R7 cells per ommatidium. Genetic screens have been used to identify mutations that alter the efficiency of signal transduction. Subsequent molecular characterization of the corresponding genes has led to the identification of a number of proteins involved in transducing the signal from the receptor to the nucleus. In contrast to the receptor and its ligand, these components are shared between different signal transduction pathways not only in Drosophila but are also homologous to components involved in signal transduction in other organisms.
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Affiliation(s)
- E Hafen
- Zoologisches Institut, Universität Zürich, Switzerland
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