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Vedelek V, Kovács AL, Juhász G, Alzyoud E, Sinka R. The tumor suppressor archipelago E3 ligase is required for spermatid differentiation in Drosophila testis. Sci Rep 2021; 11:8422. [PMID: 33875704 PMCID: PMC8055871 DOI: 10.1038/s41598-021-87656-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/31/2021] [Indexed: 02/02/2023] Open
Abstract
The human orthologue of the tumor suppressor protein FBW7 is encoded by the Drosophila archipelago (ago) gene. Ago is an F-box protein that gives substrate specificity to its SCF ubiquitin ligase complex. It has a central role in multiple biological processes in a tissue-specific manner such as cell proliferation, cellular differentiation, hypoxia-induced gene expression. Here we present a previously unknown tissue-specific role of Ago in spermatid differentiation. We identified a classical mutant of ago which is semi-lethal and male-sterile. During the characterization of ago function in testis, we found that ago plays role in spermatid development, following meiosis. We confirmed spermatogenesis defects by silencing ago by RNAi in testes. The ago mutants show multiple abnormalities in elongating and elongated spermatids, including aberration of the cyst morphology, malformed mitochondrial structures, and individualization defects. Additionally, we determined the subcellular localization of Ago protein with mCherry-Ago transgene in spermatids. Our findings highlight the potential roles of Ago in different cellular processes of spermatogenesis, like spermatid individualization, and regulation of mitochondrial morphology.
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Affiliation(s)
- Viktor Vedelek
- Department of Genetics, University of Szeged, Szeged, Hungary.
| | - Attila L Kovács
- Department of Anatomy, Cell and Developmental Biology, Eötvös Lóránd University of Science, Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Lóránd University of Science, Budapest, Hungary
| | - Elham Alzyoud
- Department of Genetics, University of Szeged, Szeged, Hungary
| | - Rita Sinka
- Department of Genetics, University of Szeged, Szeged, Hungary.
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2
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Nam S, Cho KO. Wingless and Archipelago, a fly E3 ubiquitin ligase and a homolog of human tumor suppressor FBW7, show an antagonistic relationship in wing development. BMC DEVELOPMENTAL BIOLOGY 2020; 20:14. [PMID: 32594913 PMCID: PMC7322864 DOI: 10.1186/s12861-020-00217-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 04/28/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND Archipelago (Ago) is a Drosophila homolog of mammalian F-box and WD repeat domain-containing 7 (FBW7, also known as FBXW7). In previous studies, FBW7 has been addressed as a tumor suppressor mediating ubiquitin-dependent proteolysis of several oncogenic proteins. Ubiquitination is a type of protein modification that directs protein for degradation as well as sorting. The level of beta-catenin (β-cat), an intracellular signal transducer in Wnt signaling pathway, is reduced upon overexpression of FBW7 in human cancer cell lines. Loss of function mutations in FBW7 and overactive Wnt signaling have been reported to be responsible for human cancers. RESULTS We found that Ago is important for the formation of shafts in chemosensory bristles at wing margin. This loss of shaft phenotype by knockdown of ago was rescued by knockdown of wingless (wg) whereas wing notching phenotype by knockdown of wg was rescued by knockdown of ago, establishing an antagonistic relationship between ago and wg. In line with this finding, knockdown of ago increased the level of Armadillo (Arm), a homolog of β-cat, in Drosophila tissue. Furthermore, knockdown of ago increased the level of Distal-less (Dll) and extracellular Wg in wing discs. In S2 cells, the amount of secreted Wg was increased by knockdown of Ago but decreased by Ago overexpression. Therefore, Ago plays a previously unidentified role in the inhibition of Wg secretion. Ago-overexpressing clones in wing discs exhibited accumulation of Wg in endoplasmic reticulum (ER), suggesting that Ago prevents Wg protein from moving to Golgi from ER. CONCLUSIONS We concluded that Ago plays dual roles in inhibiting Wg signaling. First, Ago decreases the level of Arm, by which Wg signaling is downregulated in Wg-responding cells. Second, Ago decreases the level of extracellular Wg by inhibiting movement of Wg from ER to Golgi in Wg-producing cells.
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Affiliation(s)
- Sujin Nam
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea
| | - Kyung-Ok Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea.
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3
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Xie J, Jin Y, Wang G. The role of SCF ubiquitin-ligase complex at the beginning of life. Reprod Biol Endocrinol 2019; 17:101. [PMID: 31779633 PMCID: PMC6883547 DOI: 10.1186/s12958-019-0547-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 11/20/2019] [Indexed: 12/22/2022] Open
Abstract
As the largest family of E3 ligases, the Skp1-cullin 1-F-box (SCF) E3 ligase complex is comprised of Cullins, Skp1 and F-box proteins. And the SCF E3 ubiquitin ligases play an important role in regulating critical cellular processes, which promote degradation of many cellular proteins, including signal transducers, cell cycle regulators, and transcription factors. We review the biological roles of the SCF ubiquitin-ligase complex in gametogenesis, oocyte-to-embryo transition, embryo development and the regulation for estrogen and progestin. We find that researches about the SCF ubiquitin-ligase complex at the beginning of life are not comprehensive, thus more in-depth researches will promote its eventual clinical application.
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Affiliation(s)
- Jiayan Xie
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, 510632, China
- School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yimei Jin
- The University of Texas MD Anderson Cancer Center & University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, 77054, USA
| | - Guang Wang
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, 510632, China.
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Bioinformatic analysis suggests potential mechanisms underlying parasitoid venom evolution and function. Genomics 2019; 112:1096-1104. [PMID: 31247332 DOI: 10.1016/j.ygeno.2019.06.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 06/18/2019] [Accepted: 06/20/2019] [Indexed: 11/21/2022]
Abstract
Hymenopteran parasitoid wasps are a diverse collection of species that infect arthropod hosts and use factors found in their venoms to manipulate host immune responses, physiology, and behaviour. Whole parasitoid venoms have been profiled using proteomic approaches, and here we present a bioinformatic characterization of the venom protein content from Ganaspis sp. 1, a parasitoid that infects flies of the genus Drosophila. We find evidence that diverse evolutionary processes including multifunctionalization, co-option, gene duplication, and horizontal gene transfer may be acting in concert to drive venom gene evolution in Ganaspis sp.1. One major role of parasitoid wasp venom is host immune evasion. We previously demonstrated that Ganaspis sp. 1 venom inhibits immune cell activation in infected Drosophila melanogaster hosts, and our current analysis has uncovered additional predicted virulence functions. Overall, this analysis represents an important step towards understanding the composition and activity of parasitoid wasp venoms.
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Vrailas-Mortimer AD, Ryan SM, Avey MJ, Mortimer NT, Dowse H, Sanyal S. p38 MAP kinase regulates circadian rhythms in Drosophila. J Biol Rhythms 2014; 29:411-26. [PMID: 25403440 DOI: 10.1177/0748730414555183] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The large repertoire of circadian rhythms in diverse organisms depends on oscillating central clock genes, input pathways for entrainment, and output pathways for controlling rhythmic behaviors. Stress-activated p38 MAP Kinases (p38K), although sparsely investigated in this context, show circadian rhythmicity in mammalian brains and are considered part of the circadian output machinery in Neurospora. We find that Drosophila p38Kb is expressed in clock neurons, and mutants in p38Kb either are arrhythmic or have a longer free-running periodicity, especially as they age. Paradoxically, similar phenotypes are observed through either transgenic inhibition or activation of p38Kb in clock neurons, suggesting a requirement for optimal p38Kb function for normal free-running circadian rhythms. We also find that p38Kb genetically interacts with multiple downstream targets to regulate circadian locomotor rhythms. More specifically, p38Kb interacts with the period gene to regulate period length and the strength of rhythmicity. In addition, we show that p38Kb suppresses the arrhythmic behavior associated with inhibition of a second p38Kb target, the transcription factor Mef2. Finally, we find that manipulating p38K signaling in free-running conditions alters the expression of another downstream target, MNK/Lk6, which has been shown to cycle with the clock and to play a role in regulating circadian rhythms. These data suggest that p38Kb may affect circadian locomotor rhythms through the regulation of multiple downstream pathways.
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Affiliation(s)
- Alysia D Vrailas-Mortimer
- Cell Biology Department, Emory University School of Medicine, Atlanta, Georgia Department of Biological Sciences, University of Denver, Denver, Colorado
| | - Sarah M Ryan
- Department of Biological Sciences, University of Denver, Denver, Colorado
| | - Matthew J Avey
- Department of Biological Sciences, University of Denver, Denver, Colorado
| | - Nathan T Mortimer
- Department of Biological Sciences, University of Denver, Denver, Colorado
| | - Harold Dowse
- School of Biology and Ecology and Department of Mathematics and Statistics, University of Maine, Orono, Maine
| | - Subhabrata Sanyal
- Cell Biology Department, Emory University School of Medicine, Atlanta, Georgia Department of Neurology Research, BiogenIdec, Cambridge, Massachusetts
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Li L, Anderson S, Secombe J, Eisenman RN. The Drosophila ubiquitin-specific protease Puffyeye regulates dMyc-mediated growth. Development 2013; 140:4776-87. [PMID: 24173801 PMCID: PMC3833434 DOI: 10.1242/dev.096941] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 09/17/2013] [Indexed: 12/13/2022]
Abstract
The essential and highly conserved role of Myc in organismal growth and development is dependent on the control of Myc protein abundance. It is now well established that Myc levels are in part regulated by ubiquitin-dependent proteasomal degradation. Using a genetic screen for modifiers of Drosophila Myc (dMyc)-induced growth, we identified and characterized a ubiquitin-specific protease (USP), Puffyeye (Puf), as a novel regulator of dMyc levels and function in vivo. We show that puf genetically and physically interacts with dMyc and the ubiquitin ligase archipelago (ago) to modulate a dMyc-dependent cell growth phenotype, and that varying Puf levels in both the eye and wing phenocopies the effects of altered dMyc abundance. Puf containing point mutations within its USP enzymatic domain failed to alter dMyc levels and displayed no detectable phenotype, indicating the importance of deubiquitylating activity for Puf function. We find that dMyc induces Ago, indicating that dMyc triggers a negative-feedback pathway that is modulated by Puf. In addition to its effects on dMyc, Puf regulates both Ago and its cell cycle substrate Cyclin E. Therefore, Puf influences cell growth by controlling the stability of key regulatory proteins.
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Affiliation(s)
- Ling Li
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle 98109, WA, USA
| | - Sarah Anderson
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle 98109, WA, USA
| | - Julie Secombe
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park, Bronx 10461, NY, USA
| | - Robert N. Eisenman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle 98109, WA, USA
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7
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Phospho-dependent ubiquitination and degradation of PAR-1 regulates synaptic morphology and tau-mediated Aβ toxicity in Drosophila. Nat Commun 2013; 3:1312. [PMID: 23271647 DOI: 10.1038/ncomms2278] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 11/12/2012] [Indexed: 01/31/2023] Open
Abstract
The conserved kinases PAR-1/MARK are critically involved in processes such as asymmetric cell division, cell polarity and neuronal differentiation. Their deregulation has been implicated in diseases including Alzheimer's disease and cancer. Given the importance of PAR-1/MARK in health and disease, their activities need to be tightly controlled. However, little is known about the molecular mechanisms underlying their regulation in vivo. Here we show that in Drosophila, a phosphorylation-dependent ubiquitination mechanism restrains PAR-1 activation. Active PAR-1 generated by LKB1-controlled phosphorylation is targeted for ubiquitination and degradation by SCF (Skp, Cullin, F-box containing complex) (Slimb), whose action is antagonized by the deubiquitinating enzyme fat facets. This newly identified PAR-1-modifying module critically regulates synaptic morphology and tau-mediated postsynaptic toxicity of amyloid precursor protein (APP)/Aβ-42, the causative agents of Alzheimer's disease, at the Drosophila neuromuscular junction. Our results provide new insights into the regulation of PAR-1 in various physiological processes and offer new therapeutic strategies for diseases involving PAR-1/MARK deregulation.
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8
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Mortimer NT, Moberg KH. The archipelago ubiquitin ligase subunit acts in target tissue to restrict tracheal terminal cell branching and hypoxic-induced gene expression. PLoS Genet 2013; 9:e1003314. [PMID: 23459416 PMCID: PMC3573119 DOI: 10.1371/journal.pgen.1003314] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/22/2012] [Indexed: 12/20/2022] Open
Abstract
The Drosophila melanogaster gene archipelago (ago) encodes the F-box/WD-repeat protein substrate specificity factor for an SCF (Skp/Cullin/F-box)-type polyubiquitin ligase that inhibits tumor-like growth by targeting proteins for degradation by the proteasome. The Ago protein is expressed widely in the fly embryo and larva and promotes degradation of pro-proliferative proteins in mitotically active cells. However the requirement for Ago in post-mitotic developmental processes remains largely unexplored. Here we show that Ago is an antagonist of the physiologic response to low oxygen (hypoxia). Reducing Ago activity in larval muscle cells elicits enhanced branching of nearby tracheal terminal cells in normoxia. This tracheogenic phenotype shows a genetic dependence on sima, which encodes the HIF-1α subunit of the hypoxia-inducible transcription factor dHIF and its target the FGF ligand branchless (bnl), and is enhanced by depletion of the Drosophila Von Hippel Lindau (dVHL) factor, which is a subunit of an oxygen-dependent ubiquitin ligase that degrades Sima/HIF-1α protein in metazoan cells. Genetic reduction of ago results in constitutive expression of some hypoxia-inducible genes in normoxia, increases the sensitivity of others to mild hypoxic stimulus, and enhances the ability of adult flies to recover from hypoxic stupor. As a molecular correlate to these genetic data, we find that Ago physically associates with Sima and restricts Sima levels in vivo. Collectively, these findings identify Ago as a required element of a circuit that suppresses the tracheogenic activity of larval muscle cells by antagonizing the Sima-mediated transcriptional response to hypoxia.
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Affiliation(s)
- Nathan T. Mortimer
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- ¤ Current address: Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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9
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A Systematic Phenotypic Screen of F-box Genes Through a Tissue-specific RNAi-based Approach in Drosophila. J Genet Genomics 2012; 39:397-413. [DOI: 10.1016/j.jgg.2012.05.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 05/25/2012] [Accepted: 05/30/2012] [Indexed: 02/03/2023]
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10
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Ayyub C. Cullin-5 and cullin-2 play a role in the development of neuromuscular junction and the female germ line of Drosophila. J Genet 2012; 90:239-49. [PMID: 21869472 DOI: 10.1007/s12041-011-0062-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cullins confer substrate specificity to E3-ligases which are multi-protein complexes involved in ubiquitin-mediated protein degradation or modification. There are six cullin genes in Drosophila melanogaster. We have raised an antibody against Cul-5 and demonstrated that it expresses in neuronal and non-neuronal cells throughout development. In the embryonic tracheal system, Cul-5 is enriched at fusion sites together with E-Cadherin and Fasciclin III. Mutations of cul-5 do not affect tracheal development but do show defects in the organization of synaptic boutons at the larval neuromuscular junction where the protein is expressed in a subset of motoneuron terminals. Loss of function of another cullin gene 'cul-2' results in similar defects at the larval neuromuscular junction although cul-2;cul-5 double mutants do not show an enhanced phenotype. Both cul-2 and cul-5 mutants show similar aberrations in the development of female germ line. Our results suggest that both of these cullin proteins participate in similar developmental processes.
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Affiliation(s)
- Champakali Ayyub
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
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11
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Ouyang Y, Song Y, Lu B. dp53 Restrains ectopic neural stem cell formation in the Drosophila brain in a non-apoptotic mechanism involving Archipelago and cyclin E. PLoS One 2011; 6:e28098. [PMID: 22140513 PMCID: PMC3225381 DOI: 10.1371/journal.pone.0028098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 11/01/2011] [Indexed: 02/06/2023] Open
Abstract
Accumulating evidence suggests that tumor-initiating stem cells or cancer stem cells (CSCs) possibly originating from normal stem cells may be the root cause of certain malignancies. How stem cell homeostasis is impaired in tumor tissues is not well understood, although certain tumor suppressors have been implicated. In this study, we use the Drosophila neural stem cells (NSCs) called neuroblasts as a model to study this process. Loss-of-function of Numb, a key cell fate determinant with well-conserved mammalian counterparts, leads to the formation of ectopic neuroblasts and a tumor phenotype in the larval brain. Overexpression of the Drosophila tumor suppressor p53 (dp53) was able to suppress ectopic neuroblast formation caused by numb loss-of-function. This occurred in a non-apoptotic manner and was independent of Dacapo, the fly counterpart of the well-characterized mammalian p53 target p21 involved in cellular senescence. The observation that dp53 affected Edu incorporation into neuroblasts led us to test the hypothesis that dp53 acts through regulation of factors involved in cell cycle progression. Our results show that the inhibitory effect of dp53 on ectopic neuroblast formation was mediated largely through its regulation of Cyclin E (Cyc E). Overexpression of Cyc E was able to abrogate dp53's ability to rescue numb loss-of-function phenotypes. Increasing Cyc E levels by attenuating Archipelago (Ago), a recently identified transcriptional target of dp53 and a negative regulator of Cyc E, had similar effects. Conversely, reducing Cyc E activity by overexpressing Ago blocked ectopic neuroblast formation in numb mutant. Our results reveal an intimate connection between cell cycle progression and NSC self-renewal vs. differentiation control, and indicate that p53-mediated regulation of ectopic NSC self-renewal through the Ago/Cyc E axis becomes particularly important when NSC homeostasis is perturbed as in numb loss-of-function condition. This has important clinical implications.
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Affiliation(s)
- Yingshi Ouyang
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Yan Song
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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12
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Nicholson SC, Nicolay BN, Frolov MV, Moberg KH. Notch-dependent expression of the archipelago ubiquitin ligase subunit in the Drosophila eye. Development 2010; 138:251-60. [PMID: 21148181 DOI: 10.1242/dev.054429] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
archipelago (ago)/Fbw7 encodes a conserved protein that functions as the substrate-receptor component of a polyubiquitin ligase that suppresses tissue growth in flies and tumorigenesis in vertebrates. Ago/Fbw7 targets multiple proteins for degradation, including the G1-S regulator Cyclin E and the oncoprotein dMyc/c-Myc. Despite prominent roles in growth control, little is known about the signals that regulate Ago/Fbw7 abundance in developing tissues. Here we use the Drosophila eye as a model to identify developmental signals that regulate ago expression. We find that expression of ago mRNA and protein is induced by passage of the morphogenetic furrow (MF) and identify the hedgehog (hh) and Notch (N) pathways as elements of this inductive mechanism. Cells mutant for N pathway components, or hh-defective cells that express reduced levels of the Notch ligand Delta, fail to upregulate ago transcription in the region of the MF; reciprocally, ectopic N activation in eye discs induces expression of ago mRNA. A fragment of the ago promoter that contains consensus binding sites for the N pathway transcription factor Su(H) is bound by Su(H) and confers N-inducibility in cultured cells. The failure to upregulate ago in N pathway mutant cells correlates with accumulation of the SCF-Ago target Cyclin E in the area of the MF, and this is rescued by re-expression of ago. These data suggest a model in which N acts through ago to restrict levels of the pro-mitotic factor Cyclin E. This N-Ago-Cyclin E link represents a significant new cell cycle regulatory mechanism in the developing eye.
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Affiliation(s)
- Sarah C Nicholson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Morozova T, Hackett J, Sedaghat Y, Sonnenfeld M. The Drosophila jing gene is a downstream target in the Trachealess/Tango tracheal pathway. Dev Genes Evol 2010; 220:191-206. [PMID: 21061019 DOI: 10.1007/s00427-010-0339-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 10/08/2010] [Indexed: 11/28/2022]
Abstract
Primary branching in the Drosophila trachea is regulated by the Trachealess (Trh) and Tango (Tgo) basic helix-loop-helix-PAS (bHLH-PAS) heterodimers, the POU protein Drifter (Dfr)/Ventral Veinless (Vvl), and the Pointed (Pnt) ETS transcription factor. The jing gene encodes a zinc finger protein also required for tracheal development. Three Trh/Tgo DNA-binding sites, known as CNS midline elements, in 1.5 kb of jing 5′ cis-regulatory sequence (jing1.5) previously suggested a downstream role for jing in the pathway. Here, we show that jing is a direct downstream target of Trh/Tgo and that Vvl and Pnt are also involved in jing tracheal activation. In vivo lacZ enhancer detection assays were used to identify cis-regulatory elements mediating embryonic expression patterns of jing. A 2.8-kb jing enhancer (jing2.8) drove lacZ expression in all tracheal cell lineages, the CNS midline and Engrailed-positive segmental stripes, mimicking endogenous jing expression. A 1.3-kb element within jing2.8 drove expression that was restricted to Engrailed-positive CNS midline cells and segmental ectodermal stripes. Surprisingly, jing1.5-lacZ expression was restricted to tracheal fusion cells despite the presence of consensus DNA-binding sites for bHLH-PAS, ETS, and POU domain transcription factors. Given the absence of Trh/Tgo DNA-binding sites in the jing1.3 enhancer, these results are consistent with previous observations suggesting a combinatorial basis to Trh-/Tgo-mediated transcriptional regulation in the trachea.
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Affiliation(s)
- Tatiana Morozova
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
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14
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Sonnenfeld M, Morozova T, Hackett J, Sun X. Drosophila Jing is part of the breathless fibroblast growth factor receptor positive feedback loop. Dev Genes Evol 2010; 220:207-20. [PMID: 21061018 DOI: 10.1007/s00427-010-0342-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 10/19/2010] [Indexed: 11/28/2022]
Abstract
In the developing Drosophila trachea, extensive cell migration lays the foundation for an elaborate network of tubules to form. This process is controlled by the Drosophila fibroblast growth factor receptor, known as Breathless (Btl), whose expression is activated by the Trachealess (Trh) and Tango (Tgo) basic helix-loop-helix (bHLH)-PAS transcription factors. We previously identified the jing zinc finger transcription factor as a gene sensitive to the dosage of bHLH-PAS transcriptional activity and showed that its mutations interact genetically with those of trh and btl. Here, we demonstrate that jing is required for btl expression in the branching trachea and dominantly interacts with known regulators of btl expression, including the ETS and POU transcription factors, pointed, and drifter/ventral veinless, respectively. Furthermore, the zinc finger-containing C-terminus of Jing associates with a btl tracheal enhancer in a Trh/Tgo-dependent manner in chromatin immunoprecipitation assays in vitro and interferes with btl in vitro and in vivo. Together, our results support a model by which Jing/Trh/Tgo complexes regulate btl transcript levels during primary tracheal branching.
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Affiliation(s)
- Margaret Sonnenfeld
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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15
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Jiang L, Pearson JC, Crews ST. Diverse modes of Drosophila tracheal fusion cell transcriptional regulation. Mech Dev 2010; 127:265-80. [PMID: 20347970 DOI: 10.1016/j.mod.2010.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 03/18/2010] [Accepted: 03/21/2010] [Indexed: 10/19/2022]
Abstract
Drosophila tracheal fusion cells play multiple important roles in guiding and facilitating tracheal branch fusion. Mechanistic understanding of how fusion cells function during development requires deciphering their transcriptional circuitry. In this paper, three genes with distinct patterns of fusion cell expression were dissected by transgenic analysis to identify the cis-regulatory modules that mediate their transcription. Bioinformatic analysis involving phylogenetic comparisons coupled with mutational experiments were employed. The dysfusion bHLH-PAS gene was shown to have two fusion cell cis-regulatory modules; one driving initial expression and another autoregulatory module to enhance later transcription. Mutational dissection of the early module identified at least four distinct inputs, and included putative binding sites for ETS and POU-homeodomain proteins. The ETS transcription factor Pointed mediates the transcriptional output of the branchless/breathless signaling pathway, suggesting that this pathway directly controls dysfusion expression. Fusion cell cis-regulatory modules of CG13196 and CG15252 require two Dysfusion:Tango binding sites, but additional sequences modulate the breadth of activation in different fusion cell classes. These results begin to decode the regulatory circuitry that guides transcriptional activation of genes required for fusion cell morphogenesis.
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Affiliation(s)
- Lan Jiang
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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16
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Gilbert MM, Beam CK, Robinson BS, Moberg KH. Genetic interactions between the Drosophila tumor suppressor gene ept and the stat92E transcription factor. PLoS One 2009; 4:e7083. [PMID: 19787055 PMCID: PMC2747001 DOI: 10.1371/journal.pone.0007083] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 08/19/2009] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Tumor Susceptibility Gene-101 (TSG101) promotes the endocytic degradation of transmembrane proteins and is implicated as a mutational target in cancer, yet the effect of TSG101 loss on cell proliferation in vertebrates is uncertain. By contrast, Drosophila epithelial tissues lacking the TSG101 ortholog erupted (ept) develop as enlarged undifferentiated tumors, indicating that the gene can have anti-growth properties in a simple metazoan. A full understanding of pathways deregulated by loss of Drosophila ept will aid in understanding potential links between mammalian TSG101 and growth control. PRINCIPAL FINDINGS We have taken a genetic approach to the identification of pathways required for excess growth of Drosophila eye-antennal imaginal discs lacking ept. We find that this phenotype is very sensitive to the genetic dose of stat92E, the transcriptional effector of the Jak-Stat signaling pathway, and that this pathway undergoes strong activation in ept mutant cells. Genetic evidence indicates that stat92E contributes to cell cycle deregulation and excess cell size phenotypes that are observed among ept mutant cells. In addition, autonomous Stat92E hyper-activation is associated with altered tissue architecture in ept tumors and an effect on expression of the apical polarity determinant crumbs. CONCLUSIONS These findings identify ept as a cell-autonomous inhibitor of the Jak-Stat pathway and suggest that excess Jak-Stat signaling makes a significant contribution to proliferative and tissue architectural phenotypes that occur in ept mutant tissues.
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Affiliation(s)
- M. Melissa Gilbert
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Carolyn K. Beam
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Brian S. Robinson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
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Szuplewski S, Sandmann T, Hietakangas V, Cohen SM. Drosophila Minus is required for cell proliferation and influences Cyclin E turnover. Genes Dev 2009; 23:1998-2003. [PMID: 19723762 DOI: 10.1101/gad.1822409] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Turnover of cyclins plays a major role in oscillatory cyclin-dependent kinase (Cdk) activity and control of cell cycle progression. Here we present a novel cell cycle regulator, called minus, which influences Cyclin E turnover in Drosophila. minus mutants produce defects in cell proliferation, some of which are attributable to persistence of Cyclin E. Minus protein can interact physically with Cyclin E and the SCF Archipelago/Fbw7/Cdc4 ubiquitin-ligase complex. Minus does not affect dMyc, another known SCF(Ago) substrate in Drosophila. We propose that Minus contributes to cell cycle regulation in part by selectively controlling turnover of Cyclin E.
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Nicholson SC, Gilbert MM, Nicolay BN, Frolov MV, Moberg KH. The archipelago tumor suppressor gene limits rb/e2f-regulated apoptosis in developing Drosophila tissues. Curr Biol 2009; 19:1503-10. [PMID: 19733076 DOI: 10.1016/j.cub.2009.07.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 07/25/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The Drosophila archipelago gene (ago) encodes the specificity component of a ubiquitin ligase that targets the cyclin E and dMyc proteins for degradation. Its human ortholog, Fbw7, is commonly lost in cancers, suggesting that failure to degrade ago/Fbw7 targets drives excess tissue growth. RESULTS We find that ago loss induces hyperplasia of some organs but paradoxically reduces the size of the adult eye. This reflects a requirement for ago to restrict apoptotic activity of the rbf1/de2f1 pathway adjacent to the eye-specific morphogenetic furrow (MF): ago mutant cells display elevated de2f1 activity, express the prodeath dE2f1 targets hid and rpr, and undergo high rates of apoptosis. These phenotypes are dependent on rbf1, de2f1, hid, and the rbf1/de2f1 regulators cyclin E and dacapo but are independent of dp53. A transactivation-deficient de2f1 allele blocks MF-associated apoptosis of ago mutant cells but does not retard their clonal overgrowth, indicating that intact de2f1 function is required for the death but not overproliferation of ago cells. Epidermal growth factor receptor (EGFR) and wingless (wg) alleles also modify the ago apoptotic phenotype, indicating that these pathways may modulate the underlying sensitivity of ago mutant cells to apoptotic signals. CONCLUSIONS These data show that ago loss requires a collaborating block in cell death to efficiently drive tissue overgrowth and that this conditional phenotype reflects a role for ago in restricting apoptotic output of the rbf1/de2f1 pathway. Moreover, the susceptibility of ago mutant cells to succumb to this apoptotic program appears to depend on local variations in extracellular signaling that could thus determine tissue-specific fates of ago mutant cells.
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Affiliation(s)
- Sarah C Nicholson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Mortimer NT, Moberg KH. Regulation of Drosophila embryonic tracheogenesis by dVHL and hypoxia. Dev Biol 2009; 329:294-305. [PMID: 19285057 DOI: 10.1016/j.ydbio.2009.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 01/27/2009] [Accepted: 03/03/2009] [Indexed: 01/01/2023]
Abstract
The tracheal system of Drosophila melanogaster is an interconnected network of gas-filled epithelial tubes that develops during embryogenesis and functions as the main gas-exchange organ in the larva. Larval tracheal cells respond to hypoxia by activating a program of branching and growth driven by HIF-1alpha/sima-dependent expression of the breathless (btl) FGF receptor. By contrast, the ability of the developing embryonic tracheal system to respond to hypoxia and integrate hard-wired branching programs with sima-driven tracheal remodeling is not well understood. Here we show that embryonic tracheal cells utilize the conserved ubiquitin ligase dVHL to control the HIF-1 alpha/sima hypoxia response pathway, and identify two distinct phases of tracheal development with differing hypoxia sensitivities and outcomes: a relatively hypoxia-resistant 'early' phase during which sima activity conflicts with normal branching and stunts migration, and a relatively hypoxia-sensitive 'late' phase during which the tracheal system uses the dVHL/sima/btl pathway to drive increased branching and growth. Mutations in the archipelago (ago) gene, which antagonizes btl transcription, re-sensitize early embryos to hypoxia, indicating that their relative resistance can be reversed by elevating activity of the btl promoter. These findings reveal a second type of tracheal hypoxic response in which Sima activation conflicts with developmental tracheogenesis, and identify the dVHL and ago ubiquitin ligases as key determinants of hypoxia sensitivity in tracheal cells. The identification of an early stage of tracheal development that is vulnerable to hypoxia is an important addition to models of the invertebrate hypoxic response.
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Affiliation(s)
- Nathan T Mortimer
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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