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Mues N, Hammer K, Leatherman J. Pvr regulates cyst stem cell division in the Drosophila testis niche, and has functions distinct from Egfr. Cells Dev 2023; 173:203822. [PMID: 36400422 PMCID: PMC10033353 DOI: 10.1016/j.cdev.2022.203822] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 11/07/2022] [Accepted: 11/11/2022] [Indexed: 11/17/2022]
Abstract
Regulation of the rate of stem cell division is one of the key determinants of the abundance of differentiating progeny in stem cell-supported tissues, and mis-regulation can lead to tumorigenesis. The well-studied Drosophila testis niche is an excellent model system to study the regulation of stem cell division in vivo. This niche supports two stem cell populations-the germline stem cells (GSCs) and cyst stem cells (CySCs), which cluster around a group of cells called the hub. The differentiating cells of these two stem cell populations cooperate together to produce sperm. Signal transduction initiated by the epidermal growth factor receptor (Egfr) is a key regulatory pathway in the cyst lineage, and much of the study of this stem cell population has centered around understanding the complexities of the requirements for Egfr signaling. We examined another receptor tyrosine kinase, Pvr, the sole Drosophila PDGF/VEGF homolog, and found that it accumulates in the cyst lineage cells of the testis, while its ligand Pvf1 accumulates in the hub. Pvr inhibition caused a reduction in both CySC numbers and the proportion of CySCs in S phase, similar to Egfr inhibition. However, testes with Pvr inhibition exhibited a low-penetrance non-autonomous germ cell differentiation defect distinct from that observed with Egfr inhibition. Cyst cells with constitutively activated Pvr failed to support germ cell differentiation, as observed with constitutively activated Egfr. However, constitutively activated Pvr promoted tumorous accumulation of cyst cells outside of the niche, a phenotype not observed with constitutively activated Egfr. Thus, Egfr and Pvr have some receptor-specific functions and some shared functions in the cyst lineage cells of the testis.
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Affiliation(s)
- Nastaran Mues
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States
| | - Kenneth Hammer
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States
| | - Judith Leatherman
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States.
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2
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Kim YJ. Activity-induced synaptic structural modifications by Akt. Biochem Biophys Res Commun 2022; 621:94-100. [PMID: 35820284 DOI: 10.1016/j.bbrc.2022.06.093] [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: 05/31/2022] [Accepted: 06/28/2022] [Indexed: 11/17/2022]
Abstract
The activity-dependent regulation of synaptic structures plays a key role in synaptic development and plasticity; however, the signaling mechanisms involved remain largely unknown. The serine/threonine protein kinase Akt, a downstream effector of phosphoinositide 3-kinase (PI3K), plays a pivotal role in a wide range of physiological functions. We focused on the importance of Akt in rapid synaptic structural changes after stimulation at the Drosophila neuromuscular junction, a well-studied model synapse. Compared with wild-type larvae, akt mutants showed significantly reduced muscle size and an increased number of boutons per area, suggesting that Akt is required for proper pre- and postsynaptic growth. In addition, the level of cysteine string protein (CSP) was significantly increased, and its distribution was different in akt mutants. After high K+ single stimulation, the CSP level of akt mutant NMJs increased dramatically compared with that of wild-type NMJs. Interestingly, ghost boutons without postsynaptic specialization were found in akt mutant NMJs, and the number of these boutons was significantly increased by patterned stimulation. In contrast, the postsynaptic change in the subsynaptic reticulum (SSR) in the akt mutant occurred independent of stimulation. These results suggest that Akt functions in both pre- and postsynaptic growth and differentiation, and in particular, presynaptic action occurs in an activity-dependent manner.
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Affiliation(s)
- Yoon-Jung Kim
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, 03080, South Korea.
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3
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Variation of TNF modulates cellular immunity of gregarious and solitary locusts against fungal pathogen Metarhizium anisopliae. Proc Natl Acad Sci U S A 2022; 119:2120835119. [PMID: 35110413 PMCID: PMC8833202 DOI: 10.1073/pnas.2120835119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2021] [Indexed: 12/11/2022] Open
Abstract
Ecological immunology addresses the interactions between host immunity and the environment. Locusts display density-dependent phase transitions between solitary and gregarious locusts. In control practices and laboratory bioassays, gregarious locusts always exhibit stronger resistance to fungal pathogens than solitary locusts. However, few studies have investigated the mechanism of altered immune switch in locusts. Here, we combined mathematical simulation and experimental studies to show that gregarious locusts inhibit tumor necrosis factor (TNF) to alter immune defense by enhancing humoral defense and reducing cellular defense, and high levels of TNF reduce the survival of solitary locusts. Our study provides an important cue for understanding cellular immunity variations in response to different population densities and for improving the control efficacy of locust plagues. Changes in population density lead to phenotypic differentiation of solitary and gregarious locusts, which display different resistance to fungal pathogens; however, how to regulate their cellular immune strategies remains unknown. Here, our stochastic simulation of pathogen proliferation suggested that humoral defense always enhanced resistance to fungal pathogens, while phagocytosis sometimes reduced defense against pathogens. Further experimental data proved that gregarious locusts had significantly decreased phagocytosis of hemocytes compared to solitary locusts. Additionally, transcriptional analysis showed that gregarious locusts promoted immune effector expression (gnbp1 and dfp) and reduced phagocytic gene expression (eater) and the cytokine tumor necrosis factor (TNF). Interestingly, higher expression of the cytokine TNF in solitary locusts simultaneously promoted eater expression and inhibited gnbp1 and dfp expression. Moreover, inhibition of TNF increased the survival of solitary locusts, and injection of TNF decreased the survival of gregarious locusts after fungal infection. Therefore, our results indicate that the alerted expression of TNF regulated the immune strategy of locusts to adapt to environmental changes.
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Kurihara M, Takarada K, Inoue YH. Enhancement of leukemia-like phenotypes in Drosophila mxc mutant larvae due to activation of the RAS-MAP kinase cascade possibly via down-regulation of DE-cadherin. Genes Cells 2020; 25:757-769. [PMID: 33012036 DOI: 10.1111/gtc.12811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 01/10/2023]
Abstract
Loss of mxc gene function in mature hemocytes of Drosophila mxcmbn1 mutant results in malignant hyperplasia in larval hematopoietic tissues termed lymph glands (LGs) owing to over-proliferation of immature cells. This is a useful model for genetic analyses of leukemia progression. To identify other mutations that deteriorate the hyperplasia, we aimed to investigate whether hyper-activation of common signaling cascade enabled to enhance the phenotypes. Ectopic expression of the constitutively active forms of MAPK signaling factors in the mutant increased the hyperplasia and the number of circulating hemocytes, resulting in the production of LG fragments. The LG phenotype was related to the reduced DE-cadherin level in the mutants. Depletion of Drosophila MCRIP, involved in MAPK-induced silencing of cadherin gene expression, exhibited a similar enhancement of the mxcmbn1 phenotypes. Furthermore, expression of MMP1 proteinase that cleaves the extracellular matrix proteins increased in the mutant larvae harboring MAPK cascade activation. Depletion of Mmp1 and that of pnt (required for Mmp1 expression) suppressed the LG hyperplasia. Hence, we speculated that reduction in DE-cadherin level by either down-regulation of MCRIP or up-regulation of MMP1 was involved in the progression of the tumor phenotype. Our findings can contribute to understanding the mechanism underlying human leukemia progression.
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Affiliation(s)
- Masanori Kurihara
- Department of Insect Biomedical Research, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Kazuki Takarada
- Department of Insect Biomedical Research, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Yoshihiro H Inoue
- Department of Insect Biomedical Research, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
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Bao R, Dia SE, Issa HA, Alhusein D, Friedrich M. Comparative Evidence of an Exceptional Impact of Gene Duplication on the Developmental Evolution of Drosophila and the Higher Diptera. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Huang XD, Zhang H, He MX. A PDGF/VEGF homologue provides new insights into the nucleus grafting operation and immune response in the pearl oyster Pinctada fucata. Gene 2017; 637:1-8. [PMID: 28918252 DOI: 10.1016/j.gene.2017.09.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/30/2017] [Accepted: 09/08/2017] [Indexed: 01/26/2023]
Abstract
The platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF, PVF) family of proteins have been implicated in a wide range of biological functions in vertebrates, including cell proliferation, cell differentiation, cell migration, neural development and especially angiogenesis/vasculogenesis. In this study, a PVF gene, belonging to the PDGF/VEGF family, was cloned and characterized from Pinctada fucata. It contained an ORF of 1110bp encoding a putative protein of 369 amino acids. The deduced amino acid sequence presented the typical structural features of PDGF family members and the N-terminal signal peptide for secretion. Comparative phylogenetic analysis revealed that PfPVF shows relatively high identity with other invertebrate PVF homologues. Furthermore, gene expression analysis revealed that PfPVF is involved in not only the nucleus grafting operation and but also the response to immune stimulation. The study may help to increase understanding of the functions of molluscan PVF.
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Affiliation(s)
- Xian-De Huang
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Hua Zhang
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Mao-Xian He
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
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Cytokine signaling through Drosophila Mthl10 ties lifespan to environmental stress. Proc Natl Acad Sci U S A 2017; 114:13786-13791. [PMID: 29229844 DOI: 10.1073/pnas.1712453115] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A systems-level understanding of cytokine-mediated, intertissue signaling is one of the keys to developing fundamental insight into the links between aging and inflammation. Here, we employed Drosophila, a routine model for analysis of cytokine signaling pathways in higher animals, to identify a receptor for the growth-blocking peptide (GBP) cytokine. Having previously established that the phospholipase C/Ca2+ signaling pathway mediates innate immune responses to GBP, we conducted a dsRNA library screen for genes that modulate Ca2+ mobilization in Drosophila S3 cells. A hitherto orphan G protein coupled receptor, Methuselah-like receptor-10 (Mthl10), was a significant hit. Secondary screening confirmed specific binding of fluorophore-tagged GBP to both S3 cells and recombinant Mthl10-ectodomain. We discovered that the metabolic, immunological, and stress-protecting roles of GBP all interconnect through Mthl10. This we established by Mthl10 knockdown in three fly model systems: in hemocyte-like Drosophila S2 cells, Mthl10 knockdown decreases GBP-mediated innate immune responses; in larvae, Mthl10 knockdown decreases expression of antimicrobial peptides in response to low temperature; in adult flies, Mthl10 knockdown increases mortality rate following infection with Micrococcus luteus and reduces GBP-mediated secretion of insulin-like peptides. We further report that organismal fitness pays a price for the utilization of Mthl10 to integrate all of these various homeostatic attributes of GBP: We found that elevated GBP expression reduces lifespan. Conversely, Mthl10 knockdown extended lifespan. We describe how our data offer opportunities for further molecular interrogation of yin and yang between homeostasis and longevity.
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Restin T, Kajdi ME, Schläpfer M, Roth Z’graggen B, Booy C, Dumrese C, Beck-Schimmer B. Sevoflurane protects rat brain endothelial barrier structure and function after hypoxia-reoxygenation injury. PLoS One 2017; 12:e0184973. [PMID: 29023577 PMCID: PMC5638245 DOI: 10.1371/journal.pone.0184973] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 09/05/2017] [Indexed: 12/23/2022] Open
Abstract
Background After cerebral injury blood-brain barrier disruption significantly impairs brain homeostasis. Volatile anesthetics have been shown to be protective in ischemia-reperfusion injury scenarios. Their impact on brain endothelial cells after hypoxia-reoxygenation (H/R) has not yet been studied in detail. Methods Rat brain endothelial cells (RBE4) were exposed to severe hypoxia and reoxygenated in air in the presence or absence of sevoflurane. Changes in dextran permeability and architecture of the cellular junctional proteins ZO-1 and β-catenin were measured. To determine necrosis and apoptosis rate DNA content, LDH release and caspase activity were quantified. The role of vascular endothelial growth factor (VEGF) as an inflammatory mediator increasing vascular permeability was assessed. At the same time, it was evaluated if sevoflurane effects are mediated through VEGF. Results were analyzed by unpaired t-tests or one way-analysis of variance followed by Bonferroni’s correction. Results H/R led to a 172% increase in permeability (p<0.001), cell swelling and qualitatively but not quantitatively modified expression of ZO-1, β-catenin and F-actin. In the presence of sevoflurane during reoxygenation, barrier function improved by 96% (p = 0.042) in parallel to a decrease of the cell size and less re-arranged junction proteins and F-actin. Sevoflurane-induced improvement of the barrier function could not be explained on the level of necrosis or apoptosis as they remained unchanged independent of the presence or absence of the volatile anesthetic. Increased expression of VEGF after H/R was attenuated by sevoflurane by 34% (p = 0.004). Barrier protection provided by sevoflurane was similar to the application of a blocking VEGF-antibody. Furthermore, the protective effect of sevoflurane was abolished in the presence of recombinant VEGF. Conclusions In H/R-induced rat brain endothelial cell injury sevoflurane maintains endothelial barrier function through downregulation of VEGF, which is a key player not only in mediating injury, but also with regard to the protective effect of sevoflurane.
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Affiliation(s)
- Tanja Restin
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Marie-Elisabeth Kajdi
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Martin Schläpfer
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Birgit Roth Z’graggen
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Christa Booy
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Claudia Dumrese
- Flow Cytometry Facility, University of Zurich, Zurich, Switzerland
| | - Beatrice Beck-Schimmer
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
- Department of Anesthesiology, University of Illinois at Chicago, Chicago, United States of America
- * E-mail:
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9
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Amarnath S, Stevens LM, Stein DS. Reconstitution of Torso signaling in cultured cells suggests a role for both Trunk and Torso-like in receptor activation. Development 2017; 144:677-686. [PMID: 28087630 DOI: 10.1242/dev.146076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/30/2016] [Indexed: 12/15/2022]
Abstract
Formation of the Drosophila embryonic termini is controlled by the localized activation of the receptor tyrosine kinase Torso. Both Torso and Torso's presumed ligand, Trunk, are expressed uniformly in the early embryo. Polar activation of Torso requires Torso-like, which is expressed by follicle cells adjacent to the ends of the developing oocyte. We find that Torso expressed at high levels in cultured Drosophila cells is activated by individual application of Trunk, Torso-like or another known Torso ligand, Prothoracicotropic Hormone. In addition to assays of downstream signaling activity, Torso dimerization was detected using bimolecular fluorescence complementation. Trunk and Torso-like were active when co-transfected with Torso and when presented to Torso-expressing cells in conditioned medium. Trunk and Torso-like were also taken up from conditioned medium specifically by cells expressing Torso. At low levels of Torso, similar to those present in the embryo, Trunk and Torso-like alone were ineffective but acted synergistically to stimulate Torso signaling. Our results suggest that Torso interacts with both Trunk and Torso-like, which cooperate to mediate dimerization and activation of Torso at the ends of the Drosophila embryo.
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Affiliation(s)
- Smita Amarnath
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Patterson Labs 532, 2401 Speedway, Austin, TX 78712, USA
| | - Leslie M Stevens
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Patterson Labs 532, 2401 Speedway, Austin, TX 78712, USA
| | - David S Stein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Patterson Labs 532, 2401 Speedway, Austin, TX 78712, USA
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10
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Verna C, Sawchuk MG, Linh NM, Scarpella E. Control of vein network topology by auxin transport. BMC Biol 2015; 13:94. [PMID: 26560462 PMCID: PMC4641347 DOI: 10.1186/s12915-015-0208-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 10/28/2015] [Indexed: 02/08/2023] Open
Abstract
Background Tissue networks such as the vascular networks of plant and animal organs transport signals and nutrients in most multicellular organisms. The transport function of tissue networks depends on topological features such as the number of networks’ components and the components’ connectedness; yet what controls tissue network topology is largely unknown, partly because of the difficulties in quantifying the effects of genes on tissue network topology. We address this problem for the vein networks of plant leaves by introducing biologically motivated descriptors of vein network topology; we combine these descriptors with cellular imaging and molecular genetic analysis; and we apply this combination of approaches to leaves of Arabidopsis thaliana that lack function of, overexpress or misexpress combinations of four PIN-FORMED (PIN) genes—PIN1, PIN5, PIN6, and PIN8—which encode transporters of the plant signal auxin and are known to control vein network geometry. Results We find that PIN1 inhibits vein formation and connection, and that PIN6 acts redundantly to PIN1 in these processes; however, the functions of PIN6 in vein formation are nonhomologous to those of PIN1, while the functions of PIN6 in vein connection are homologous to those of PIN1. We further find that PIN8 provides functions redundant and homologous to those of PIN6 in PIN1-dependent inhibition of vein formation, but that PIN8 has no functions in PIN1/PIN6-dependent inhibition of vein connection. Finally, we find that PIN5 promotes vein formation; that all the vein-formation-promoting functions of PIN5 are redundantly inhibited by PIN6 and PIN8; and that these functions of PIN5, PIN6, and PIN8 are independent of PIN1. Conclusions Our results suggest that PIN-mediated auxin transport controls the formation of veins and their connection into networks. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0208-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carla Verna
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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11
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Mishra S, Kumar P, Malik A. The effect of Beauveria bassiana infection on cell mediated and humoral immune response in house fly, Musca domestica L. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:15171-15178. [PMID: 26233748 DOI: 10.1007/s11356-015-5105-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/21/2015] [Indexed: 06/04/2023]
Abstract
Entomopathogenic fungi that manifest infections by overcoming insect's immune response could be a successful control agent for the house fly, Musca domestica L. which is a major domestic, medical, and veterinary pest. In this study, the immune response of house fly to Beauveria bassiana infection was investigated to reveal fundamental aspects of house fly hemocyte biology, such as hemocyte numbers and size, which is poorly understood. The total hemocyte counts (THCs) in B. bassiana-infected house fly showed an initial increase (from 6 to 9 h), followed by subsequent decrease (9 to 12 h) with increase in time of infection. The THCs was slightly greater in infected flies than the non-infected ones. Insight into relative hemocyte counts depicted a significant increase in prohemocyte (PR) and decrease in granulocyte (GR) in infected house flies compared to non-infected ones. The relative cell area of hemocyte cells showed a noticeable increase in PR and intermediate cells (ICs), while a considerable reduction was observed for plasmatocyte (PL) and GR. The considerable variation in relative cell number and cell area in the B. bassiana-infected house flies indicated stress development during infection. The present study highlights changes occurring during B. bassiana invasion to house fly leading to establishment of infection along with facilitation in understanding of basic hemocyte biology. The results of the study is expected to help in better understanding of house fly immune response during fungal infection, so as to assist production of more efficient mycoinsecticides for house fly control using B. bassiana.
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Affiliation(s)
- Sapna Mishra
- Applied Microbiology Lab, Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, New Delhi, 110 016, India.
| | - Peeyush Kumar
- Applied Microbiology Lab, Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, New Delhi, 110 016, India
| | - Anushree Malik
- Applied Microbiology Lab, Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, New Delhi, 110 016, India
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12
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The Drosophila histone demethylase dKDM5/LID regulates hematopoietic development. Dev Biol 2015; 405:260-8. [DOI: 10.1016/j.ydbio.2015.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 06/12/2015] [Accepted: 07/12/2015] [Indexed: 01/08/2023]
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13
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Sopko R, Lin YB, Makhijani K, Alexander B, Perrimon N, Brückner K. A systems-level interrogation identifies regulators of Drosophila blood cell number and survival. PLoS Genet 2015; 11:e1005056. [PMID: 25749252 PMCID: PMC4352040 DOI: 10.1371/journal.pgen.1005056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 02/05/2015] [Indexed: 12/12/2022] Open
Abstract
In multicellular organisms, cell number is typically determined by a balance of intracellular signals that positively and negatively regulate cell survival and proliferation. Dissecting these signaling networks facilitates the understanding of normal development and tumorigenesis. Here, we study signaling by the Drosophila PDGF/VEGF Receptor (Pvr) in embryonic blood cells (hemocytes) and in the related cell line Kc as a model for the requirement of PDGF/VEGF receptors in vertebrate cell survival and proliferation. The system allows the investigation of downstream and parallel signaling networks, based on the ability of Pvr to activate Ras/Erk, Akt/TOR, and yet-uncharacterized signaling pathway/s, which redundantly mediate cell survival and contribute to proliferation. Using Kc cells, we performed a genome wide RNAi screen for regulators of cell number in a sensitized, Pvr deficient background. We identified the receptor tyrosine kinase (RTK) Insulin-like receptor (InR) as a major Pvr Enhancer, and the nuclear hormone receptors Ecdysone receptor (EcR) and ultraspiracle (usp), corresponding to mammalian Retinoid X Receptor (RXR), as Pvr Suppressors. In vivo analysis in the Drosophila embryo revealed a previously unrecognized role for EcR to promote apoptotic death of embryonic blood cells, which is balanced with pro-survival signaling by Pvr and InR. Phosphoproteomic analysis demonstrates distinct modes of cell number regulation by EcR and RTK signaling. We define common phosphorylation targets of Pvr and InR that include regulators of cell survival, and unique targets responsible for specialized receptor functions. Interestingly, our analysis reveals that the selection of phosphorylation targets by signaling receptors shows qualitative changes depending on the signaling status of the cell, which may have wide-reaching implications for other cell regulatory systems.
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Affiliation(s)
- Richelle Sopko
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - You Bin Lin
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Kalpana Makhijani
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Brandy Alexander
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston, Massachusetts, United States of America
| | - Katja Brückner
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States of America
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, United States of America
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14
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Mondal BC, Shim J, Evans CJ, Banerjee U. Pvr expression regulators in equilibrium signal control and maintenance of Drosophila blood progenitors. eLife 2014; 3:e03626. [PMID: 25201876 PMCID: PMC4185420 DOI: 10.7554/elife.03626] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 09/05/2014] [Indexed: 12/18/2022] Open
Abstract
Blood progenitors within the lymph gland, a larval organ that supports hematopoiesis in Drosophila melanogaster, are maintained by integrating signals emanating from niche-like cells and those from differentiating blood cells. We term the signal from differentiating cells the 'equilibrium signal' in order to distinguish it from the 'niche signal'. Earlier we showed that equilibrium signaling utilizes Pvr (the Drosophila PDGF/VEGF receptor), STAT92E, and adenosine deaminase-related growth factor A (ADGF-A) (Mondal et al., 2011). Little is known about how this signal initiates during hematopoietic development. To identify new genes involved in lymph gland blood progenitor maintenance, particularly those involved in equilibrium signaling, we performed a genetic screen that identified bip1 (bric à brac interacting protein 1) and Nucleoporin 98 (Nup98) as additional regulators of the equilibrium signal. We show that the products of these genes along with the Bip1-interacting protein RpS8 (Ribosomal protein S8) are required for the proper expression of Pvr.
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Affiliation(s)
- Bama Charan Mondal
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Jiwon Shim
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
- Department of Life Science, Hanyang University, Seoul, Republic of Korea
| | - Cory J Evans
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Utpal Banerjee
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, United States
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Tsuzuki S, Matsumoto H, Furihata S, Ryuda M, Tanaka H, Sung EJ, Bird GS, Zhou Y, Shears SB, Hayakawa Y. Switching between humoral and cellular immune responses in Drosophila is guided by the cytokine GBP. Nat Commun 2014; 5:4628. [PMID: 25130174 DOI: 10.1038/ncomms5628] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 07/08/2014] [Indexed: 11/09/2022] Open
Abstract
Insects combat infection through carefully measured cellular (for example, phagocytosis) and humoral (for example, secretion of antimicrobial peptides (AMPs)) innate immune responses. Little is known concerning how these different defense mechanisms are coordinated. Here, we use insect plasmatocytes and hemocyte-like Drosophila S2 cells to characterize mechanisms of immunity that operate in the haemocoel. We demonstrate that a Drosophila cytokine, growth-blocking peptides (GBP), acts through the phospholipase C (PLC)/Ca(2+) signalling cascade to mediate the secretion of Pvf, a ligand for platelet-derived growth factor- and vascular endothelial growth factor-receptor (Pvr) homologue. Activated Pvr recruits extracellular signal-regulated protein kinase to inhibit humoral immune responses, while stimulating cell 'spreading', an initiating event in cellular immunity. The double-stranded RNA (dsRNA)-targeted knockdown of either Pvf2 or Pvr inhibits GBP-mediated cell spreading and activates AMP expression. Conversely, Pvf2 overexpression enhances cell spreading but inhibits AMP expression. Thus, we describe mechanisms to initiate immune programs that are either humoral or cellular in nature, but not both; such immunophysiological polarization may minimize homeostatic imbalance during infection.
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Affiliation(s)
- Seiji Tsuzuki
- 1] Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan [2]
| | - Hitoshi Matsumoto
- 1] Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan [2]
| | - Shunsuke Furihata
- Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
| | - Masasuke Ryuda
- Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
| | - Hirotoshi Tanaka
- Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
| | - Eui Jae Sung
- Inositol Signaling Section, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA
| | - Gary S Bird
- 1] Inositol Signaling Section, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [2] Calcium Regulation Section, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA
| | - Yixing Zhou
- Inositol Signaling Section, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA
| | - Stephen B Shears
- Inositol Signaling Section, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA
| | - Yoichi Hayakawa
- Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
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16
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Lu H, Syka J, Chiu T, Poon PW. Prolonged sound exposure has different effects on increasing neuronal size in the auditory cortex and brainstem. Hear Res 2014; 314:42-50. [DOI: 10.1016/j.heares.2014.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 05/25/2014] [Indexed: 10/25/2022]
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17
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Ashton-Beaucage D, Udell CM, Gendron P, Sahmi M, Lefrançois M, Baril C, Guenier AS, Duchaine J, Lamarre D, Lemieux S, Therrien M. A functional screen reveals an extensive layer of transcriptional and splicing control underlying RAS/MAPK signaling in Drosophila. PLoS Biol 2014; 12:e1001809. [PMID: 24643257 PMCID: PMC3958334 DOI: 10.1371/journal.pbio.1001809] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 02/05/2014] [Indexed: 12/11/2022] Open
Abstract
A global RNAi screening approach in Drosophila cells identifies a large group of transcription and splicing factors that modulate RAS/MAPK signaling by altering the expression of MAPK. The small GTPase RAS is among the most prevalent oncogenes. The evolutionarily conserved RAF-MEK-MAPK module that lies downstream of RAS is one of the main conduits through which RAS transmits proliferative signals in normal and cancer cells. Genetic and biochemical studies conducted over the last two decades uncovered a small set of factors regulating RAS/MAPK signaling. Interestingly, most of these were found to control RAF activation, thus suggesting a central regulatory role for this event. Whether additional factors are required at this level or further downstream remains an open question. To obtain a comprehensive view of the elements functionally linked to the RAS/MAPK cascade, we used a quantitative assay in Drosophila S2 cells to conduct a genome-wide RNAi screen for factors impacting RAS-mediated MAPK activation. The screen led to the identification of 101 validated hits, including most of the previously known factors associated to this pathway. Epistasis experiments were then carried out on individual candidates to determine their position relative to core pathway components. While this revealed several new factors acting at different steps along the pathway—including a new protein complex modulating RAF activation—we found that most hits unexpectedly work downstream of MEK and specifically influence MAPK expression. These hits mainly consist of constitutive splicing factors and thereby suggest that splicing plays a specific role in establishing MAPK levels. We further characterized two representative members of this group and surprisingly found that they act by regulating mapk alternative splicing. This study provides an unprecedented assessment of the factors modulating RAS/MAPK signaling in Drosophila. In addition, it suggests that pathway output does not solely rely on classical signaling events, such as those controlling RAF activation, but also on the regulation of MAPK levels. Finally, it indicates that core splicing components can also specifically impact alternative splicing. The RAS/MAPK pathway is a cornerstone of the cell proliferation signaling apparatus. It has a notable involvement in cancer as mutations in the components of the pathway are associated with aberrant proliferation. Previous work has focused predominantly on post-translational regulation of RAS/MAPK signaling such that a large and intricate network of factors is now known to act on core pathway components. However, regulation at the pre-translational level has not been examined nearly as extensively and is comparatively poorly understood. In this study, we used an unbiased and global screening approach to survey the Drosophila genome—using Drosophila cultured cells—for novel regulators of this pathway. Surprisingly, a majority of our hits were associated to either transcription or mRNA splicing. We used a series of secondary screening assays to determine which part of the RAS/MAPK pathway these candidates target. We found that these factors were not equally distributed along the pathway, but rather converged predominantly on mapk mRNA expression and processing. Our findings raise the intriguing possibility that regulation of mapk transcript production is a key step for a diverse set of regulatory inputs, and may play an important part in RAS/MAPK signaling dynamics.
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Affiliation(s)
- Dariel Ashton-Beaucage
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Christian M. Udell
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Patrick Gendron
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Malha Sahmi
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Martin Lefrançois
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Caroline Baril
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Anne-Sophie Guenier
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Jean Duchaine
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Daniel Lamarre
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Sébastien Lemieux
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département d'informatique et de recherche opérationnelle, Université de Montréal, Montréal, Québec, Canada
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département de pathologie et de biologie cellulaire, Université de Montréal, Montréal, Québec, Canada
- * E-mail:
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18
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Mbodj A, Junion G, Brun C, Furlong EEM, Thieffry D. Logical modelling of Drosophila signalling pathways. MOLECULAR BIOSYSTEMS 2014; 9:2248-58. [PMID: 23868318 DOI: 10.1039/c3mb70187e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A limited number of signalling pathways are involved in the specification of cell fate during the development of all animals. Several of these pathways were originally identified in Drosophila. To clarify their roles, and possible cross-talk, we have built a logical model for the nine key signalling pathways recurrently used in metazoan development. In each case, we considered the associated ligands, receptors, signal transducers, modulators, and transcription factors reported in the literature. Implemented using the logical modelling software GINsim, the resulting models qualitatively recapitulate the main characteristics of each pathway, in wild type as well as in various mutant situations (e.g. loss-of-function or gain-of-function). These models constitute pluggable modules that can be used to assemble comprehensive models of complex developmental processes. Moreover, these models of Drosophila pathways could serve as scaffolds for more complicated models of orthologous mammalian pathways. Comprehensive model annotations and GINsim files are provided for each of the nine considered pathways.
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Affiliation(s)
- Abibatou Mbodj
- Technological Advances for Genomics and Clinics (TAGC), INSERM UMR_S 1090, Aix-Marseille Université, Marseille, France.
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19
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Miettinen TP, Pessa HKJ, Caldez MJ, Fuhrer T, Diril MK, Sauer U, Kaldis P, Björklund M. Identification of transcriptional and metabolic programs related to mammalian cell size. Curr Biol 2014; 24:598-608. [PMID: 24613310 PMCID: PMC3991852 DOI: 10.1016/j.cub.2014.01.071] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/20/2013] [Accepted: 01/30/2014] [Indexed: 12/16/2022]
Abstract
Background Regulation of cell size requires coordination of growth and proliferation. Conditional loss of cyclin-dependent kinase 1 in mice permits hepatocyte growth without cell division, allowing us to study cell size in vivo using transcriptomics and metabolomics. Results Larger cells displayed increased expression of cytoskeletal genes but unexpectedly repressed expression of many genes involved in mitochondrial functions. This effect appears to be cell autonomous because cultured Drosophila cells induced to increase cell size displayed a similar gene-expression pattern. Larger hepatocytes also displayed a reduction in the expression of lipogenic transcription factors, especially sterol-regulatory element binding proteins. Inhibition of mitochondrial functions and lipid biosynthesis, which is dependent on mitochondrial metabolism, increased the cell size with reciprocal effects on cell proliferation in several cell lines. Conclusions We uncover that large cell-size increase is accompanied by downregulation of mitochondrial gene expression, similar to that observed in diabetic individuals. Mitochondrial metabolism and lipid synthesis are used to couple cell size and cell proliferation. This regulatory mechanism may provide a possible mechanism for sensing metazoan cell size. Gene expression and metabolites levels relative to cell size are analyzed in liver Mitochondrial gene expression is repressed cell-autonomously in larger cells Cell size can be modulated by targeting mitochondria functions and lipid synthesis Lipids are negative regulators of cell size because they promote cell proliferation
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Affiliation(s)
- Teemu P Miettinen
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Heli K J Pessa
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Matias J Caldez
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 61 Biopolis Drive, Proteos #03-09, Singapore 138673, Singapore; Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore
| | - Tobias Fuhrer
- Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule Zürich, Wolfgang-Pauli Strasse 16, 8093 Zürich, Switzerland
| | - M Kasim Diril
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 61 Biopolis Drive, Proteos #03-09, Singapore 138673, Singapore
| | - Uwe Sauer
- Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule Zürich, Wolfgang-Pauli Strasse 16, 8093 Zürich, Switzerland
| | - Philipp Kaldis
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 61 Biopolis Drive, Proteos #03-09, Singapore 138673, Singapore; Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore
| | - Mikael Björklund
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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20
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Yamamoto K, Gandin V, Sasaki M, McCracken S, Li W, Silvester J, Elia A, Wang F, Wakutani Y, Alexandrova R, Oo Y, Mullen PJ, Inoue S, Itsumi M, Lapin V, Haight J, Wakeham A, Shahinian A, Ikura M, Topisirovic I, Sonenberg N, Mak T. Largen: A Molecular Regulator of Mammalian Cell Size Control. Mol Cell 2014; 53:904-15. [DOI: 10.1016/j.molcel.2014.02.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 11/26/2013] [Accepted: 02/13/2014] [Indexed: 12/31/2022]
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21
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Parsons B, Foley E. The Drosophila platelet-derived growth factor and vascular endothelial growth factor-receptor related (Pvr) protein ligands Pvf2 and Pvf3 control hemocyte viability and invasive migration. J Biol Chem 2013; 288:20173-83. [PMID: 23737520 DOI: 10.1074/jbc.m113.483818] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) family members are essential and evolutionary conserved determinants of blood cell development and dispersal. In addition, VEGFs are integral to vascular growth and permeability with detrimental contributions to ischemic diseases and metastatic cancers. The PDGF/VEGF-receptor related (Pvr) protein is implicated in the migration and trophic maintenance of macrophage-like hemocytes in Drosophila melanogaster embryos. pvr mutants have a depleted hemocyte population and a breakdown in hemocyte distribution. Previous studies suggested redundant functions for the Pvr ligands, Pvf2 and Pvf3 in the regulation of hemocyte migration, proliferation, and size. However, the precise roles that Pvf2 and Pvf3 play in hematopoiesis remain unclear due to the lack of available mutants. To determine Pvf2 and Pvf3 functions in vivo, we generated a genomic deletion that simultaneously disrupts Pvf2 and Pvf3. From our studies, we identified contributions of Pvf2 and Pvf3 to the Pvr trophic maintenance of hemocytes. Furthermore, we uncovered a novel role for Pvfs in invasive migrations. We showed that Pvf2 and Pvf3 are not required for the directed migration of hemocytes, but act locally in epithelial cells to coordinate trans-epithelial migration of hemocytes. Our findings redefine Pvf roles in hemocyte migration and highlight novel Pvf roles in hemocyte invasive migration. These new parallels between the Pvr and PDGF/VEGF pathways extend the utility of the Drosophila embryonic system to dissect physiological and pathological roles of PDGF/VEGF-like growth factors.
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Affiliation(s)
- Brendon Parsons
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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22
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Bond D, Foley E. Autocrine platelet-derived growth factor-vascular endothelial growth factor receptor-related (Pvr) pathway activity controls intestinal stem cell proliferation in the adult Drosophila midgut. J Biol Chem 2012; 287:27359-70. [PMID: 22722927 DOI: 10.1074/jbc.m112.378018] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A dynamic pool of undifferentiated somatic stem cells proliferate and differentiate to replace dead or dying mature cell types and maintain the integrity and function of adult tissues. Intestinal stem cells (ISCs) in the Drosophila posterior midgut are a well established model to study the complex genetic circuitry that governs stem cell homeostasis. Exposure of the intestinal epithelium to environmental toxins results in the expression of cytokines and growth factors that drive the rapid proliferation and differentiation of ISCs. In the absence of stress signals, ISC homeostasis is maintained through intrinsic pathways. In this study, we uncovered the PDGF- and VEGF-receptor related (Pvr) pathway as an essential regulator of ISC homeostasis under unstressed conditions in the posterior midgut. We found that Pvr is coexpressed with its ligand Pvf2 in ISCs and that hyperactivation of the Pvr pathway distorts the ISC developmental program and drives intestinal dysplasia. In contrast, we show that mutant ISCs in the Pvf/Pvr pathway are defective in homeostatic proliferation and differentiation, resulting in a failure to generate mature cell types. Additionally, we determined that extrinsic stress signals generated by enteropathogenic infection are epistatic to the hypoplasia generated in Pvf/Pvr mutants, making the Pvr pathway unique among all previously studied intrinsic pathways. Our findings illuminate an evolutionarily conserved signal transduction pathway with essential roles in metazoan embryonic development and direct involvement in numerous disease states.
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Affiliation(s)
- David Bond
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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23
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Mondal BC, Mukherjee T, Mandal L, Evans CJ, Sinenko SA, Martinez-Agosto JA, Banerjee U. Interaction between differentiating cell- and niche-derived signals in hematopoietic progenitor maintenance. Cell 2012; 147:1589-600. [PMID: 22196733 DOI: 10.1016/j.cell.2011.11.041] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 04/16/2011] [Accepted: 11/16/2011] [Indexed: 12/20/2022]
Abstract
Maintenance of a hematopoietic progenitor population requires extensive interaction with cells within a microenvironment or niche. In the Drosophila hematopoietic organ, niche-derived Hedgehog signaling maintains the progenitor population. Here, we show that the hematopoietic progenitors also require a signal mediated by Adenosine deaminase growth factor A (Adgf-A) arising from differentiating cells that regulates extracellular levels of adenosine. The adenosine signal opposes the effects of Hedgehog signaling within the hematopoietic progenitor cells and the magnitude of the adenosine signal is kept in check by the level of Adgf-A secreted from differentiating cells. Our findings reveal signals arising from differentiating cells that are required for maintaining progenitor cell quiescence and that function with the niche-derived signal in maintaining the progenitor state. Similar homeostatic mechanisms are likely to be utilized in other systems that maintain relatively large numbers of progenitors that are not all in direct contact with the cells of the niche.
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Affiliation(s)
- Bama Charan Mondal
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
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24
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Rohn JL, Sims D, Liu T, Fedorova M, Schöck F, Dopie J, Vartiainen MK, Kiger AA, Perrimon N, Baum B. Comparative RNAi screening identifies a conserved core metazoan actinome by phenotype. ACTA ACUST UNITED AC 2012; 194:789-805. [PMID: 21893601 PMCID: PMC3171124 DOI: 10.1083/jcb.201103168] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RNAi screens in Drosophila and human cells for novel actin
regulators revealed conserved roles for proteins involved in nuclear actin
export, RNA splicing, and ubiquitination. Although a large number of actin-binding proteins and their regulators have been
identified through classical approaches, gaps in our knowledge remain. Here, we
used genome-wide RNA interference as a systematic method to define metazoan
actin regulators based on visual phenotype. Using comparative screens in
cultured Drosophila and human cells, we generated phenotypic
profiles for annotated actin regulators together with proteins bearing predicted
actin-binding domains. These phenotypic clusters for the known metazoan
“actinome” were used to identify putative new core actin
regulators, together with a number of genes with conserved but poorly studied
roles in the regulation of the actin cytoskeleton, several of which we studied
in detail. This work suggests that although our search for new components of the
core actin machinery is nearing saturation, regulation at the level of nuclear
actin export, RNA splicing, ubiquitination, and other upstream processes remains
an important but unexplored frontier of actin biology.
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Affiliation(s)
- Jennifer L Rohn
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England, UK.
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25
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Horn T, Sandmann T, Fischer B, Axelsson E, Huber W, Boutros M. Mapping of signaling networks through synthetic genetic interaction analysis by RNAi. Nat Methods 2011; 8:341-6. [PMID: 21378980 DOI: 10.1038/nmeth.1581] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 02/04/2011] [Indexed: 12/28/2022]
Abstract
The analysis of synthetic genetic interaction networks can reveal how biological systems achieve a high level of complexity with a limited repertoire of components. Studies in yeast and bacteria have taken advantage of collections of deletion strains to construct matrices of quantitative interaction profiles and infer gene function. Yet comparable approaches in higher organisms have been difficult to implement in a robust manner. Here we report a method to identify genetic interactions in tissue culture cells through RNAi. By performing more than 70,000 pairwise perturbations of signaling factors, we identified >600 interactions affecting different quantitative phenotypes of Drosophila melanogaster cells. Computational analysis of this interaction matrix allowed us to reconstruct signaling pathways and identify a conserved regulator of Ras-MAPK signaling. Large-scale genetic interaction mapping by RNAi is a versatile, scalable approach for revealing gene function and the connectivity of cellular networks.
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Affiliation(s)
- Thomas Horn
- German Cancer Research Center (Deutsches Krebsforschungszentrum), Division Signaling and Functional Genomics and Heidelberg University, Department of Cell and Molecular Biology, Faculty of Medicine Mannheim, Heidelberg, Germany
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26
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Ponnambalam S, Alberghina M. Evolution of the VEGF-regulated vascular network from a neural guidance system. Mol Neurobiol 2011; 43:192-206. [PMID: 21271303 DOI: 10.1007/s12035-011-8167-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 01/12/2011] [Indexed: 12/27/2022]
Abstract
The vascular network is closely linked to the neural system, and an interdependence is displayed in healthy and in pathophysiological responses. How has close apposition of two such functionally different systems occurred? Here, we present a hypothesis for the evolution of the vascular network from an ancestral neural guidance system. Biological cornerstones of this hypothesis are the vascular endothelial growth factor (VEGF) protein family and cognate receptors. The primary sequences of such proteins are conserved from invertebrates, such as worms and flies that lack discernible vascular systems compared to mammals, but all these systems have sophisticated neuronal wiring involving such molecules. Ancestral VEGFs and receptors (VEGFRs) could have been used to develop and maintain the nervous system in primitive eukaryotes. During evolution, the demands of increased morphological complexity required systems for transporting molecules and cells, i.e., biological conductive tubes. We propose that the VEGF-VEGFR axis was subverted by evolution to mediate the formation of biological tubes necessary for transport of fluids, e.g., blood. Increasingly, there is evidence that aberrant VEGF-mediated responses are also linked to neuronal dysfunctions ranging from motor neuron disease, stroke, Parkinson's disease, Alzheimer's disease, ischemic brain disease, epilepsy, multiple sclerosis, and neuronal repair after injury, as well as common vascular diseases (e.g., retinal disease). Manipulation and correction of the VEGF response in different neural tissues could be an effective strategy to treat different neurological diseases.
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Affiliation(s)
- Sreenivasan Ponnambalam
- Endothelial Cell Biology Unit, Institute of Molecular & Cellular Biology, LIGHT Laboratories, University of Leeds, Leeds, UK.
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27
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Lindquist RA, Ottina KA, Wheeler DB, Hsu PP, Thoreen CC, Guertin DA, Ali SM, Sengupta S, Shaul YD, Lamprecht MR, Madden KL, Papallo AR, Jones TR, Sabatini DM, Carpenter AE. Genome-scale RNAi on living-cell microarrays identifies novel regulators of Drosophila melanogaster TORC1-S6K pathway signaling. Genome Res 2011; 21:433-46. [PMID: 21239477 DOI: 10.1101/gr.111492.110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The evolutionarily conserved target of rapamycin complex 1 (TORC1) controls cell growth in response to nutrient availability and growth factors. TORC1 signaling is hyperactive in cancer, and regulators of TORC1 signaling may represent therapeutic targets for human diseases. To identify novel regulators of TORC1 signaling, we performed a genome-scale RNA interference screen on microarrays of Drosophila melanogaster cells expressing human RPS6, a TORC1 effector whose phosphorylated form we detected by immunofluorescence. Our screen revealed that the TORC1-S6K-RPS6 signaling axis is regulated by many subcellular components, including the Class I vesicle coat (COPI), the spliceosome, the proteasome, the nuclear pore, and the translation initiation machinery. Using additional RNAi reagents, we confirmed 70 novel genes as significant on-target regulators of RPS6 phosphorylation, and we characterized them with extensive secondary assays probing various arms of the TORC1 pathways, identifying functional relationships among those genes. We conclude that cell-based microarrays are a useful platform for genome-scale and secondary screening in Drosophila, revealing regulators that may represent drug targets for cancers and other diseases of deregulated TORC1 signaling.
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Affiliation(s)
- Robert A Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
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28
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Clustering phenotype populations by genome-wide RNAi and multiparametric imaging. Mol Syst Biol 2010; 6:370. [PMID: 20531400 PMCID: PMC2913390 DOI: 10.1038/msb.2010.25] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 04/12/2010] [Indexed: 02/07/2023] Open
Abstract
Genetic screens for phenotypic similarity have made key contributions to associating genes with biological processes. With RNA interference (RNAi), highly parallel phenotyping of loss-of-function effects in cells has become feasible. One of the current challenges however is the computational categorization of visual phenotypes and the prediction of biological function and processes. In this study, we describe a combined computational and experimental approach to discover novel gene functions and explore functional relationships. We performed a genome-wide RNAi screen in human cells and used quantitative descriptors derived from high-throughput imaging to generate multiparametric phenotypic profiles. We show that profiles predicted functions of genes by phenotypic similarity. Specifically, we examined several candidates including the largely uncharacterized gene DONSON, which shared phenotype similarity with known factors of DNA damage response (DDR) and genomic integrity. Experimental evidence supports that DONSON is a novel centrosomal protein required for DDR signalling and genomic integrity. Multiparametric phenotyping by automated imaging and computational annotation is a powerful method for functional discovery and mapping the landscape of phenotypic responses to cellular perturbations.
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29
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Abstract
RNA interference (RNAi) is an effective tool for genome-scale, high-throughput analysis of gene function. In the past five years, a number of genome-scale RNAi high-throughput screens (HTSs) have been done in both Drosophila and mammalian cultured cells to study diverse biological processes, including signal transduction, cancer biology, and host cell responses to infection. Results from these screens have led to the identification of new components of these processes and, importantly, have also provided insights into the complexity of biological systems, forcing new and innovative approaches to understanding functional networks in cells. Here, we review the main findings that have emerged from RNAi HTS and discuss technical issues that remain to be improved, in particular the verification of RNAi results and validation of their biological relevance. Furthermore, we discuss the importance of multiplexed and integrated experimental data analysis pipelines to RNAi HTS.
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Affiliation(s)
- Stephanie Mohr
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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Evans IR, Hu N, Skaer H, Wood W. Interdependence of macrophage migration and ventral nerve cord development in Drosophila embryos. Development 2010; 137:1625-33. [PMID: 20392742 PMCID: PMC2860247 DOI: 10.1242/dev.046797] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2010] [Indexed: 11/20/2022]
Abstract
During embryonic development, Drosophila macrophages (haemocytes) undergo a series of stereotypical migrations to disperse throughout the embryo. One major migratory route is along the ventral nerve cord (VNC), where haemocytes are required for the correct development of this tissue. We show, for the first time, that a reciprocal relationship exists between haemocytes and the VNC and that defects in nerve cord development prevent haemocyte migration along this structure. Using live imaging, we demonstrate that the axonal guidance cue Slit and its receptor Robo are both required for haemocyte migration, but signalling is not autonomously required in haemocytes. We show that the failure of haemocyte migration along the VNC in slit mutants is not due to a lack of chemotactic signals within this structure, but rather to a failure in its detachment from the overlying epithelium, creating a physical barrier to haemocyte migration. This block of haemocyte migration in turn disrupts the formation of the dorsoventral channels within the VNC, further highlighting the importance of haemocyte migration for correct neural development. This study illustrates the important role played by the three-dimensional environment in directing cell migration in vivo and reveals an intriguing interplay between the developing nervous system and the blood cells within the fly, demonstrating that their development is both closely coupled and interdependent.
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Affiliation(s)
- Iwan R. Evans
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Nan Hu
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Helen Skaer
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Will Wood
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
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Nir O, Bakal C, Perrimon N, Berger B. Inference of RhoGAP/GTPase regulation using single-cell morphological data from a combinatorial RNAi screen. Genome Res 2010; 20:372-80. [PMID: 20144944 DOI: 10.1101/gr.100248.109] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Biological networks are highly complex systems, consisting largely of enzymes that act as molecular switches to activate/inhibit downstream targets via post-translational modification. Computational techniques have been developed to perform signaling network inference using some high-throughput data sources, such as those generated from transcriptional and proteomic studies, but comparable methods have not been developed to use high-content morphological data, which are emerging principally from large-scale RNAi screens, to these ends. Here, we describe a systematic computational framework based on a classification model for identifying genetic interactions using high-dimensional single-cell morphological data from genetic screens, apply it to RhoGAP/GTPase regulation in Drosophila, and evaluate its efficacy. Augmented by knowledge of the basic structure of RhoGAP/GTPase signaling, namely, that GAPs act directly upstream of GTPases, we apply our framework for identifying genetic interactions to predict signaling relationships between these proteins. We find that our method makes mediocre predictions using only RhoGAP single-knockdown morphological data, yet achieves vastly improved accuracy by including original data from a double-knockdown RhoGAP genetic screen, which likely reflects the redundant network structure of RhoGAP/GTPase signaling. We consider other possible methods for inference and show that our primary model outperforms the alternatives. This work demonstrates the fundamental fact that high-throughput morphological data can be used in a systematic, successful fashion to identify genetic interactions and, using additional elementary knowledge of network structure, to infer signaling relations.
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Affiliation(s)
- Oaz Nir
- Department of Mathematics, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA
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Bond D, Foley E. A quantitative RNAi screen for JNK modifiers identifies Pvr as a novel regulator of Drosophila immune signaling. PLoS Pathog 2009; 5:e1000655. [PMID: 19893628 PMCID: PMC2766254 DOI: 10.1371/journal.ppat.1000655] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 10/13/2009] [Indexed: 01/08/2023] Open
Abstract
Drosophila melanogaster responds to gram-negative bacterial challenges through the IMD pathway, a signal transduction cassette that is driven by the coordinated activities of JNK, NF-κB and caspase modules. While many modifiers of NF-κB activity were identified in cell culture and in vivo assays, the regulatory apparatus that determines JNK inputs into the IMD pathway is relatively unexplored. In this manuscript, we present the first quantitative screen of the entire genome of Drosophila for novel regulators of JNK activity in the IMD pathway. We identified a large number of gene products that negatively or positively impact on JNK activation in the IMD pathway. In particular, we identified the Pvr receptor tyrosine kinase as a potent inhibitor of JNK activation. In a series of in vivo and cell culture assays, we demonstrated that activation of the IMD pathway drives JNK-dependent expression of the Pvr ligands, Pvf2 and Pvf3, which in turn act through the Pvr/ERK MAP kinase pathway to attenuate the JNK and NF-κB arms of the IMD pathway. Our data illuminate a poorly understood arm of a critical and evolutionarily conserved innate immune response. Furthermore, given the pleiotropic involvement of JNK in eukaryotic cell biology, we believe that many of the novel regulators identified in this screen are of interest beyond immune signaling. Innate immunity is the sole immune response in the overwhelming majority of multicellular organisms and drives the sophisticated antigen-specific adaptive defenses of vertebrates. Defective regulation of immune signal transduction pathways has disastrous consequences for affected individuals and can result in life-threatening conditions that include cancer, autoimmune and neurological conditions. Thus, there is a major need to identify the regulatory circuits that govern activation of critical innate immune response pathways. The genetically accessible model organism Drosophila melanogaster is an ideal springboard for such studies, as core aspects of innate immune pathways are evolutionarily conserved and novel discoveries in Drosophila often inspire subsequent developments in the characterization of biomedically relevant mammalian pathways. Drosophila responses to certain bacterial invaders proceed through the IMD pathway, which contains partially overlapping signal transduction JNK and NF-κB arms. While substantial efforts have illuminated much of the NF-κB arm, there is a considerable paucity of information on the regulation of the JNK arm. We conducted a survey of the entire Drosophila genome for novel regulators the Imd/dJNK pathway. In this study, we uncovered a novel link between the proliferative Pvr pathway and the IMD pathway.
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Affiliation(s)
- David Bond
- Department of Medical Microbiology and Immunology, University of Alberta, Alberta Institute for Viral Immunology, Edmonton, Alberta, Canada
| | - Edan Foley
- Department of Medical Microbiology and Immunology, University of Alberta, Alberta Institute for Viral Immunology, Edmonton, Alberta, Canada
- * E-mail:
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Lu HP, Chen ST, Poon PWF. Enlargement of neuronal size in rat auditory cortex after prolonged sound exposure. Neurosci Lett 2009; 463:145-9. [DOI: 10.1016/j.neulet.2009.07.075] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 06/06/2009] [Accepted: 07/24/2009] [Indexed: 10/20/2022]
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