1
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Russell SL, Castillo JR, Sullivan WT. Wolbachia endosymbionts manipulate the self-renewal and differentiation of germline stem cells to reinforce fertility of their fruit fly host. PLoS Biol 2023; 21:e3002335. [PMID: 37874788 PMCID: PMC10597519 DOI: 10.1371/journal.pbio.3002335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 09/14/2023] [Indexed: 10/26/2023] Open
Abstract
The alphaproteobacterium Wolbachia pipientis infects arthropod and nematode species worldwide, making it a key target for host biological control. Wolbachia-driven host reproductive manipulations, such as cytoplasmic incompatibility (CI), are credited for catapulting these intracellular bacteria to high frequencies in host populations. Positive, perhaps mutualistic, reproductive manipulations also increase infection frequencies, but are not well understood. Here, we identify molecular and cellular mechanisms by which Wolbachia influences the molecularly distinct processes of germline stem cell (GSC) self-renewal and differentiation. We demonstrate that wMel infection rescues the fertility of flies lacking the translational regulator mei-P26 and is sufficient to sustain infertile homozygous mei-P26-knockdown stocks indefinitely. Cytology revealed that wMel mitigates the impact of mei-P26 loss through restoring proper pMad, Bam, Sxl, and Orb expression. In Oregon R files with wild-type fertility, wMel infection elevates lifetime egg hatch rates. Exploring these phenotypes through dual-RNAseq quantification of eukaryotic and bacterial transcripts revealed that wMel infection rescues and offsets many gene expression changes induced by mei-P26 loss at the mRNA level. Overall, we show that wMel infection beneficially reinforces host fertility at mRNA, protein, and phenotypic levels, and these mechanisms may promote the emergence of mutualism and the breakdown of host reproductive manipulations.
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Affiliation(s)
- Shelbi L. Russell
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Jennie Ruelas Castillo
- Division of Infectious Diseases, Department of Medicine, The Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - William T. Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
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2
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Identification of sex-specific splicing via comparative transcriptome analysis of gonads from sea cucumber Apostichopus japonicus. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2023; 45:101031. [PMID: 36371882 DOI: 10.1016/j.cbd.2022.101031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/31/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
Alternative splicing (AS) is an essential post-transcriptional regulation mechanism for sex differentiation and gonadal development, which has rarely been reported in marine invertebrates. Sea cucumber (Apostichopus japonicus) is an economically important marine benthic echinoderm with a potential XX/XY sex determination mechanism, whose molecular mechanism in the gonadal differentiation has not been clearly understood. In this study, we analyzed available RNA-seq datasets of male and female gonads to explore if AS mechanism exerts an essential function in sex differentiation and gonadal development of A. japonicus. In our results, a total of 20,338 AS events from 7219 alternatively spliced genes, and 189 sexually differential alternative splicing (DAS) events from 156 genes were identified in gonadal transcriptome of sea cucumber. Gene Ontology analysis indicated that these DAS genes were significantly enriched in spermatogenesis-related GO terms. Maximal Clique Centrality (MCC) was then applied for protein-protein interaction (PPI) analysis to search for protein interactions and hub DAS gene. Among all DAS genes, we identified 10 DAS genes closely related to spermatogenesis and (or) sperm motility and a hub gene dnah1. Thus, this study revealed that alternative isoforms were generated from certain genes in female and male gonads through alternative splicing, which may provide direct evidence that alternative splicing mechanisms participate in female and male gonads. These results suggested a novel perspective for explaining the molecular mechanisms underlying gonadal differentiation between male and female sea cucumbers.
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3
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Saccone G. A history of the genetic and molecular identification of genes and their functions controlling insect sex determination. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 151:103873. [PMID: 36400424 DOI: 10.1016/j.ibmb.2022.103873] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The genetics of the sex determination regulatory cascade in Drosophila melanogaster has a fascinating history, interlinked with the foundation of the Genetics discipline itself. The discovery that alternative splicing rather than differential transcription is the molecular mechanism underlying the upstream control of sex differences in the Drosophila model system was surprising. This notion is now fully integrated into the scientific canon, appearing in many genetics textbooks and online education resources. In the last three decades, it was a key reference point for starting evolutionary studies in other insect species by using homology-based approaches. This review will introduce a very brief history of Drosophila genetics. It will describe the genetic and molecular approaches applied for the identifying and cloning key genes involved in sex determination in Drosophila and in many other insect species. These comparative analyses led to supporting the idea that sex-determining pathways have evolved mainly by recruiting different upstream signals/genes while maintaining widely conserved intermediate and downstream regulatory genes. The review also provides examples of the link between technological advances and research achievements, to stimulate reflections on how science is produced. It aims to hopefully strengthen the related historical and conceptual knowledge of general readers of other disciplines and of younger geneticists, often focused on the latest technical-molecular approaches.
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Affiliation(s)
- Giuseppe Saccone
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126, Naples, Italy.
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4
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Colonnetta MM, Abrahante JE, Schedl P, Gohl DM, Deshpande G. CLAMP regulates zygotic genome activation in Drosophila embryos. Genetics 2021; 219:iyab107. [PMID: 34849887 PMCID: PMC8633140 DOI: 10.1093/genetics/iyab107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/15/2020] [Indexed: 11/13/2022] Open
Abstract
Embryonic patterning is critically dependent on zygotic genome activation (ZGA). In Drosophila melanogaster embryos, the pioneer factor Zelda directs ZGA, possibly in conjunction with other factors. Here, we have explored the novel involvement of Chromatin-Linked Adapter for MSL Proteins (CLAMP) during ZGA. CLAMP binds thousands of sites genome-wide throughout early embryogenesis. Interestingly, CLAMP relocates to target promoter sequences across the genome when ZGA is initiated. Although there is a considerable overlap between CLAMP and Zelda binding sites, the proteins display distinct temporal dynamics. To assess whether CLAMP occupancy affects gene expression, we analyzed transcriptomes of embryos zygotically compromised for either clamp or zelda and found that transcript levels of many zygotically activated genes are similarly affected. Importantly, compromising either clamp or zelda disrupted the expression of critical segmentation and sex determination genes bound by CLAMP (and Zelda). Furthermore, clamp knockdown embryos recapitulate other phenotypes observed in Zelda-depleted embryos, including nuclear division defects, centrosome aberrations, and a disorganized actomyosin network. Based on these data, we propose that CLAMP acts in concert with Zelda to regulate early zygotic transcription.
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Affiliation(s)
- Megan M Colonnetta
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Juan E Abrahante
- University of Minnesota Informatics Institute, Minneapolis, MN 55455, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Daryl M Gohl
- University of Minnesota Genomics Center, Minneapolis, MN 55455, USA
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
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5
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Wang M, Xie X, Xu D, Wang Z, Yu G, Jin Z, Zhu D. Molecular characterization of the Sex-lethal gene in mud crab Scylla paramamosain and its potential role in sexual development. Comp Biochem Physiol B Biochem Mol Biol 2020; 250:110486. [DOI: 10.1016/j.cbpb.2020.110486] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/26/2020] [Accepted: 08/02/2020] [Indexed: 12/18/2022]
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6
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Das P, Salazar JL, Li-Kroeger D, Yamamoto S, Nakamura M, Sasamura T, Inaki M, Masuda W, Kitagawa M, Yamakawa T, Matsuno K. Maternal almondex, a neurogenic gene, is required for proper subcellular Notch distribution in early Drosophila embryogenesis. Dev Growth Differ 2019; 62:80-93. [PMID: 31782145 DOI: 10.1111/dgd.12639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 10/08/2019] [Indexed: 01/03/2023]
Abstract
Notch signaling plays crucial roles in the control of cell fate and physiology through local cell-cell interactions. The core processes of Notch signal transduction are well established, but the mechanisms that fine-tune the pathway in various developmental and post-developmental contexts are less clear. Drosophila almondex, which encodes an evolutionarily conserved double-pass transmembrane protein, was identified in the 1970s as a maternal-effect gene that regulates Notch signaling in certain contexts, but its mechanistic function remains obscure. In this study, we examined the role of almondex in Notch signaling during early Drosophila embryogenesis. We found that in addition to being required for lateral inhibition in the neuroectoderm, almondex is also partially required for Notch signaling-dependent single-minded expression in the mesectoderm. Furthermore, we found that almondex is required for proper subcellular Notch receptor distribution in the neuroectoderm, specifically during mid-stage 5 development. The absence of maternal almondex during this critical window of time caused Notch to accumulate abnormally in cells in a mesh-like pattern. This phenotype did not include any obvious change in subcellular Delta ligand distribution, suggesting that it does not result from a general vesicular-trafficking defect. Considering that dynamic Notch trafficking regulates signal output to fit the specific context, we speculate that almondex may facilitate Notch activation by regulating intracellular Notch receptor distribution during early embryogenesis.
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Affiliation(s)
- Puspa Das
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Jose L Salazar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - David Li-Kroeger
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Mitsutoshi Nakamura
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Takeshi Sasamura
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Mikiko Inaki
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Wataru Masuda
- Department of Pathology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Motoo Kitagawa
- Department of Biochemistry, International University of Health and Welfare, School of Medicine, Chiba, Japan
| | - Tomoko Yamakawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Kenji Matsuno
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
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7
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Moschall R, Rass M, Rossbach O, Lehmann G, Kullmann L, Eichner N, Strauss D, Meister G, Schneuwly S, Krahn MP, Medenbach J. Drosophila Sister-of-Sex-lethal reinforces a male-specific gene expression pattern by controlling Sex-lethal alternative splicing. Nucleic Acids Res 2019; 47:2276-2288. [PMID: 30590805 PMCID: PMC6411925 DOI: 10.1093/nar/gky1284] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/04/2018] [Accepted: 12/14/2018] [Indexed: 01/14/2023] Open
Abstract
In Drosophila, female development is governed by a single RNA-binding protein, Sex-lethal (Sxl), that controls the expression of key factors involved in dosage compensation, germline homeostasis and the establishment of female morphology and behaviour. Sxl expression in female flies is maintained by an auto-regulatory, positive feedback loop with Sxl controlling splicing of its own mRNA. Until now, it remained unclear how males prevent accidental triggering of the Sxl expression cascade and protect themselves against runaway protein production. Here, we identify the protein Sister-of-Sex-lethal (Ssx) as an inhibitor of Sxl auto-regulatory splicing. Sxl and Ssx have a comparable RNA-binding specificity and compete for binding to RNA regulatory elements present in the Sxl transcript. In cultured Drosophila cells, Sxl-induced changes to alternative splicing can be reverted by the expression of Ssx. Moreover, in adult male flies ablation of the ssx gene results in a low level of productive Sxl mRNA splicing and Sxl protein production in isolated, clonal cell populations. In sum, this demonstrates that Ssx safeguards male animals against Sxl protein production to reinforce a stable, male-specific gene expression pattern.
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Affiliation(s)
- Rebecca Moschall
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Mathias Rass
- Institute of Zoology, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Oliver Rossbach
- Institute of Biochemistry, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
| | - Gerhard Lehmann
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Lars Kullmann
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Norbert Eichner
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Daniela Strauss
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Gunter Meister
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Stephan Schneuwly
- Institute of Zoology, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
| | - Michael P Krahn
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany.,Medical Clinic D, University of Muenster, Domagkstrasse 3, D-48149 Muenster, Germany
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
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8
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Zheng J, Cheng S, Jia Y, Gu Z, Li F, Chi M, Liu S, Jiang W. Molecular identification and expression profiles of four splice variants of Sex-lethal gene in Cherax quadricarinatus. Comp Biochem Physiol B Biochem Mol Biol 2019; 234:26-33. [DOI: 10.1016/j.cbpb.2019.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/17/2019] [Accepted: 05/01/2019] [Indexed: 12/25/2022]
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9
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Sandler JE, Irizarry J, Stepanik V, Dunipace L, Amrhein H, Stathopoulos A. A Developmental Program Truncates Long Transcripts to Temporally Regulate Cell Signaling. Dev Cell 2019; 47:773-784.e6. [PMID: 30562515 DOI: 10.1016/j.devcel.2018.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/30/2018] [Accepted: 11/13/2018] [Indexed: 11/29/2022]
Abstract
Rapid mitotic divisions and a fixed transcription rate limit the maximal length of transcripts in early Drosophila embryos. Previous studies suggested that transcription of long genes is initiated but aborted, as early nuclear divisions have short interphases. Here, we identify long genes that are expressed during short nuclear cycles as truncated transcripts. The RNA binding protein Sex-lethal physically associates with transcripts for these genes and is required to support early termination to specify shorter transcript isoforms in early embryos of both sexes. In addition, one truncated transcript for the gene short-gastrulation encodes a product in embryos that functionally relates to a previously characterized dominant-negative form, which maintains TGF-β signaling in the off-state. In summary, our results reveal a developmental program of short transcripts functioning to help temporally regulate Drosophila embryonic development, keeping cell signaling at early stages to a minimum in order to support its proper initiation at cellularization.
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Affiliation(s)
- Jeremy E Sandler
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jihyun Irizarry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Vincent Stepanik
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Leslie Dunipace
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry Amrhein
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Angelike Stathopoulos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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10
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Carter TY, Gadwala S, Chougule AB, Bui APN, Sanders AC, Chaerkady R, Cormier N, Cole RN, Thomas JH. Actomyosin contraction during cellularization is regulated in part by Src64 control of Actin 5C protein levels. Genesis 2019; 57:e23297. [PMID: 30974046 DOI: 10.1002/dvg.23297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 03/27/2019] [Indexed: 11/09/2022]
Abstract
Src64 is required for actomyosin contraction during cellularization of the Drosophila embryonic blastoderm. The mechanism of actomyosin ring constriction is poorly understood even though a number of cytoskeletal regulators have been implicated in the assembly, organization, and contraction of these microfilament rings. How these cytoskeletal processes are regulated during development is even less well understood. To investigate the role of Src64 as an upstream regulator of actomyosin contraction, we conducted a proteomics screen to identify proteins whose expression levels are controlled by src64. Global levels of actin are reduced in src64 mutant embryos. Furthermore, we show that reduction of the actin isoform Actin 5C causes defects in actomyosin contraction during cellularization similar to those caused by src64 mutation, indicating that a relatively high level of Actin 5C is required for normal actomyosin contraction and furrow canal structure. However, reduction of Actin 5C levels only slows down actomyosin ring constriction rather than preventing it, suggesting that src64 acts not only to modulate actin levels, but also to regulate the actomyosin cytoskeleton by other means.
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Affiliation(s)
- Tammy Y Carter
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Swetha Gadwala
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Ashish B Chougule
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Anh P N Bui
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Alex C Sanders
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Raghothama Chaerkady
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nathaly Cormier
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Robert N Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jeffrey H Thomas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
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11
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Zheng ZZ, Sun X, Zhang B, Pu J, Jiang ZY, Li M, Fan YJ, Xu YZ. Alternative splicing regulation of doublesex gene by RNA-binding proteins in the silkworm Bombyx mori. RNA Biol 2019; 16:809-820. [PMID: 30836863 DOI: 10.1080/15476286.2019.1590177] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Doublesex is highly conserved and sex-specifically spliced in insect sex-determination pathways, and its alternative splicing (AS) is regulated by Transformer, an exonic splicing activator, in the model system of Drosophila melanogaster. However, due to the lack of a transformer gene, AS regulation of doublesex remains unclear in Lepidoptera, which contain the economically important silkworm Bombyx mori and thousands of agricultural pests. Here, we use yeast three-hybrid system to screen for RNA-binding proteins that recognize sex-specific exons 3 and 4 of silkworm doublesex (Bm-dsx); this approach identified BxRBP1/Lark binding to the exon 3, and BxRBP2/TBPH and BxRBP3/Aret binding to the exon 4. Investigation of tissues shows that BxRBP1 and BxRBP2 have no sex specificity, but BxRBP3 has - three of its four isoforms are expressed with a sex-bias. Using novel sex-specific silkworm cell lines, we find that BxRBP1 and BxRBP3 directly interact with each other, and cooperatively function as splicing repressors. Over-expression of BxRBP1 and BxRBP3 isoforms efficiently inhibits splicing of the exons 3 and 4 in the female-specific cells and generates the male-specific isoform of Bm-dsx. We also demonstrate that the sex-determination upstream gene Masc regulates alternatively transcribed BxRBP3 isoforms. Thus, we identify a new regulatory mechanism of doublesex AS in the silkworm, revealing an evolutionary divergence in insect sex-determination.
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Affiliation(s)
- Zeng-Zhang Zheng
- a Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Science , Institute of Plant Physiology and Ecology, Chinese Academy of Sciences , Shanghai , China
| | - Xia Sun
- b College of Life Technology , Jiangsu University of Science and Technology , Zhenjiang , China
| | - Bei Zhang
- a Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Science , Institute of Plant Physiology and Ecology, Chinese Academy of Sciences , Shanghai , China
| | - Jia Pu
- a Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Science , Institute of Plant Physiology and Ecology, Chinese Academy of Sciences , Shanghai , China
| | - Ze-Yu Jiang
- a Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Science , Institute of Plant Physiology and Ecology, Chinese Academy of Sciences , Shanghai , China
| | - Muwang Li
- b College of Life Technology , Jiangsu University of Science and Technology , Zhenjiang , China
| | - Yu-Jie Fan
- c College of Life Science , Wuhan University , Wuhan , China
| | - Yong-Zhen Xu
- c College of Life Science , Wuhan University , Wuhan , China
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12
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Insight into Notch Signaling Steps That Involve pecanex from Dominant-Modifier Screens in Drosophila. Genetics 2018; 209:1099-1119. [PMID: 29853475 DOI: 10.1534/genetics.118.300935] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/22/2018] [Indexed: 12/14/2022] Open
Abstract
Notch signaling plays crucial roles in intercellular communications. In Drosophila, the pecanex (pcx) gene, which encodes an evolutionarily conserved multi-pass transmembrane protein, appears to be required to activate Notch signaling in some contexts, especially during neuroblast segregation in the neuroectoderm. Although Pcx has been suggested to contribute to endoplasmic reticulum homeostasis, its functions remain unknown. Here, to elucidate these roles, we performed genetic modifier screens of pcx We found that pcx heterozygotes lacking its maternal contribution exhibit cold-sensitive lethality, which is attributed to a reduction in Notch signaling at decreased temperatures. Using sets of deletions that uncover most of the second and third chromosomes, we identified four enhancers and two suppressors of the pcx cold-sensitive lethality. Among these, five genes encode known Notch-signaling components: big brain, Delta (Dl), neuralized (neur), Brother of Bearded A (BobA), a member of the Bearded (Brd) family, and N-ethylmaleimide-sensitive factor 2 (Nsf2). We showed that BobA suppresses Dl endocytosis during neuroblast segregation in the neuroectoderm, as Brd family genes reportedly do in the mesoderm for mesectoderm specification. Analyses of Nsf2, a key regulator of vesicular fusion, suggested a novel role in neuroblast segregation, which is distinct from Nsf2's previously reported role in imaginal tissues. Finally, jim lovell, which encodes a potential transcription factor, may play a role in Notch signaling during neuroblast segregation. These results reveal new research avenues for Pcx functions and Notch signaling.
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13
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Morita S, Ota R, Kobayashi S. Downregulation of NHP2 promotes proper cyst formation in Drosophila ovary. Dev Growth Differ 2018; 60:248-259. [PMID: 29845608 DOI: 10.1111/dgd.12539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/13/2018] [Accepted: 04/25/2018] [Indexed: 01/21/2023]
Abstract
In Drosophila ovary, germline stem cells (GSCs) divide to produce two daughter cells. One daughter is maintained as a GSC, whereas the other initiates cyst formation, a process involving four synchronous mitotic divisions that form 2-, 4-, 8-, and 16-cell cysts. In this study, we found that reduction in the level of NHP2, a component of the H/ACA small nucleolar ribonucleoprotein complex that catalyzes rRNA pseudouridylation, promotes progression to 8-cell cysts. NHP2 protein was concentrated in the nucleoli of germline cells during cyst formation. NHP2 expression, as well as the nucleolar size, abruptly decreased during progression from 2-cell to 4-cell cysts. Reduction in NHP2 activity in the germline caused accumulation of 4- and 8-cell cysts and decreased the number of single cells. In addition, NHP2 knockdown impaired the transition to 16-cell cysts. Furthermore, a tumorous phenotype caused by Sex-lethal (Sxl) knockdown, which is characterized by accumulation of single and two-cell cysts, was partially rescued by NHP2 knockdown. When Sxl and NHP2 activities were concomitantly repressed, the numbers of four- and eight-cell cysts were increased. In addition, Sxl protein physically interacted with NHP2 mRNA in ovaries. Thus, it is reasonable to conclude that Sxl represses NHP2 activity at the post-transcriptional level to promote proper cyst formation. Because NHP2 knockdown did not affect global protein synthesis in the germarium, we speculate that changes in NHP2-dependent pseudouridylation, which is involved in translation of specific mRNAs, must be intact in order to promote proper cyst formation.
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Affiliation(s)
- Shumpei Morita
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Ryoma Ota
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Satoru Kobayashi
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Ibaraki, Japan
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14
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López-Cuadros I, García-Gasca A, Gomez-Anduro G, Escobedo-Fregoso C, Llera-Herrera RA, Ibarra AM. Isolation of the sex-determining gene Sex-lethal (Sxl) in Penaeus (Litopenaeus) vannamei (Boone, 1931) and characterization of its embryogenic, gametogenic, and tissue-specific expression. Gene 2018; 668:33-47. [PMID: 29758296 DOI: 10.1016/j.gene.2018.05.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 12/11/2022]
Abstract
The Pacific white shrimp Penaeus vannamei is the most cultured shrimp species around the world. Because females grow larger than males, the culture of 'only females' is of great interest, but knowledge on sex determination and differentiation is required for producing only females. In an effort to obtain information associated with reproduction in P. vannamei, transcriptomic data from female gonads was generated, and partial sequences of a transcript were identified as Sex-lethal (Sxl). Its characterization indicated that, differently from other penaeids in which this gene has been isolated, there are six isoforms of the Sxl transcript in P. vannamei (PvanSxl 1-6). These isoforms result from alternative splicing at three splice sites (SS1, SS2, SS3). The first splice-site is unique to P. vannamei, as it has not been reported for other Arthropod species; the second splice-site (SS2) is common among crustaceans, and the third splice-site (SS3) is also unique to P. vannamei and when spliced-out, it is always together with SS2. All isoforms are expressed during embryogenesis as well as gametogenesis of both genders. The two shorter isoforms, PvanSxl-5 and PvanSxl-6, which result from the splicing of SS2 and SS3, were found mostly expressed in adult testis, but PvanSxl-6 was also expressed in oocytes during gametogenesis. During oogenesis, the second largest isoform, PvanSxl-2, which splices-out only SS1, and PvanSxl-4 that splices-out SS1 and SS2 were highly expressed. These two isoforms were also highly expressed during embryonic development. In situ hybridization allowed pinpointing more specifically the cells where the PvanSxl transcripts were expressed. During embryogenesis, hybridization was observed from the one-cell stage embryo to late gastrula. In the female gonad in previtellogenesis, hybridization occurred in the nucleus of oocytes, whereas in secondary vitellogenesis the transcript also hybridized cytoplasmic granules and cortical crypts. Finally, in situ hybridization corroborated the expression of PvanSxl also in the male gonad during spermatogenesis, mostly occurring in the cytoplasm from spermatogonia and spermatocytes.
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Affiliation(s)
- Itzia López-Cuadros
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico
| | - Alejandra García-Gasca
- Centro de Investigación en Alimentación y Desarrollo A.C., (CIAD) Unidad Mazatlán, Av. Sábalo-Cerritos S/N. Col. Estero del Yugo, C.P. 82000 Mazatlán, Sinaloa, Mexico
| | - Gracia Gomez-Anduro
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico
| | - Cristina Escobedo-Fregoso
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico; CONACYT, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Ciudad de México 03940, Mexico
| | - Raúl A Llera-Herrera
- Centro de Investigación en Alimentación y Desarrollo A.C., (CIAD) Unidad Mazatlán, Av. Sábalo-Cerritos S/N. Col. Estero del Yugo, C.P. 82000 Mazatlán, Sinaloa, Mexico; CONACYT, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Ciudad de México 03940, Mexico
| | - Ana M Ibarra
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico.
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15
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Abstract
Several lineages of symbiotic bacteria in insects selfishly manipulate host reproduction to spread in a population 1 , often by distorting host sex ratios. Spiroplasma poulsonii2,3 is a helical and motile, Gram-positive symbiotic bacterium that resides in a wide range of Drosophila species 4 . A notable feature of S. poulsonii is male killing, whereby the sons of infected female hosts are selectively killed during development1,2. Although male killing caused by S. poulsonii has been studied since the 1950s, its underlying mechanism is unknown. Here we identify an S. poulsonii protein, designated Spaid, whose expression induces male killing. Overexpression of Spaid in D. melanogaster kills males but not females, and induces massive apoptosis and neural defects, recapitulating the pathology observed in S. poulsonii-infected male embryos5-11. Our data suggest that Spaid targets the dosage compensation machinery on the male X chromosome to mediate its effects. Spaid contains ankyrin repeats and a deubiquitinase domain, which are required for its subcellular localization and activity. Moreover, we found a laboratory mutant strain of S. poulsonii with reduced male-killing ability and a large deletion in the spaid locus. Our study has uncovered a bacterial protein that affects host cellular machinery in a sex-specific way, which is likely to be the long-searched-for factor responsible for S. poulsonii-induced male killing.
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16
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Ota R, Morita S, Sato M, Shigenobu S, Hayashi M, Kobayashi S. Transcripts immunoprecipitated with Sxl protein in primordial germ cells of Drosophila embryos. Dev Growth Differ 2017; 59:713-723. [PMID: 29124738 DOI: 10.1111/dgd.12408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/26/2017] [Accepted: 09/27/2017] [Indexed: 12/11/2022]
Abstract
In Drosophila, Sex lethal (Sxl), an RNA binding protein, is required for induction of female sexual identity in both somatic and germline cells. Although the Sxl-dependent feminizing pathway in the soma was previously elucidated, the downstream targets for Sxl in the germline remained elusive. To identify these target genes, we selected transcripts associated with Sxl in primordial germ cells (PGCs) of embryos using RNA immunoprecipitation coupled to sequencing (RIP-seq) analysis. A total of 308 transcripts encoded by 282 genes were obtained. Seven of these genes, expressed at higher levels in PGCs as determined by microarray and in situ hybridization analyses, were subjected to RNAi-mediated functional analyses. Knockdown of Neos, Kap-alpha3, and CG32075 throughout germline development caused gonadal dysgenesis in a sex-dependent manner, and Su(var)2-10 knockdown caused gonadal dysgenesis in both sexes. Moreover, as with knockdown of Sxl, knockdown of Su(var)2-10 in PGCs gave rise to a tumorous phenotype of germline cells in ovaries. Because this phenotype indicates loss of female identity of germline cells, we consider Su(var)2-10 to be a strong candidate target of Sxl in PGCs. Our results represent a first step toward elucidating the Sxl-dependent feminizing pathway in the germline.
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Affiliation(s)
- Ryoma Ota
- Life Science Center of Tsukuba Advanced Research Alliance (TARA Center), University of Tsukuba, Tsukuba, 305-8577, Japan
| | - Shumpei Morita
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Masanao Sato
- Laboratory of Applied Molecular Entomology, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Shuji Shigenobu
- Functional Genomics Facility, NIBB Core Research Facilities, National Institute for Basic Biology, Nishigo-naka 38, Myodaiji, Okazaki, 444-8585, Japan
| | - Makoto Hayashi
- Life Science Center of Tsukuba Advanced Research Alliance (TARA Center), University of Tsukuba, Tsukuba, 305-8577, Japan
| | - Satoru Kobayashi
- Life Science Center of Tsukuba Advanced Research Alliance (TARA Center), University of Tsukuba, Tsukuba, 305-8577, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
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17
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Ochoa-Espinosa A, Harmansa S, Caussinus E, Affolter M. Myosin II is not required for Drosophila tracheal branch elongation and cell intercalation. Development 2017; 144:2961-2968. [PMID: 28811312 DOI: 10.1242/dev.148940] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 07/05/2017] [Indexed: 01/04/2023]
Abstract
The Drosophila tracheal system consists of an interconnected network of monolayered epithelial tubes that ensures oxygen transport in the larval and adult body. During tracheal dorsal branch (DB) development, individual DBs elongate as a cluster of cells, led by tip cells at the front and trailing cells in the rear. Branch elongation is accompanied by extensive cell intercalation and cell lengthening of the trailing stalk cells. Although cell intercalation is governed by Myosin II (MyoII)-dependent forces during tissue elongation in the Drosophila embryo that lead to germ-band extension, it remained unclear whether MyoII plays a similar active role during tracheal branch elongation and intercalation. Here, we have used a nanobody-based approach to selectively knock down MyoII in tracheal cells. Our data show that, despite the depletion of MyoII function, tip cell migration and stalk cell intercalation (SCI) proceed at a normal rate. This confirms a model in which DB elongation and SCI in the trachea occur as a consequence of tip cell migration, which produces the necessary forces for the branching process.
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Affiliation(s)
| | - Stefan Harmansa
- Biozentrum, University of Basel, Klingelbergstr. 50/70, 4056 Basel, Switzerland
| | - Emmanuel Caussinus
- Institute of Molecular Life Sciences (IMLS), University of Zurich, 8057 Zurich, Switzerland
| | - Markus Affolter
- Biozentrum, University of Basel, Klingelbergstr. 50/70, 4056 Basel, Switzerland
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18
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The Drosophila DAXX-Like Protein (DLP) Cooperates with ASF1 for H3.3 Deposition and Heterochromatin Formation. Mol Cell Biol 2017; 37:MCB.00597-16. [PMID: 28320872 DOI: 10.1128/mcb.00597-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/09/2017] [Indexed: 01/22/2023] Open
Abstract
Histone variants are nonallelic isoforms of canonical histones, and they are deposited, in contrast to canonical histones, in a replication-independent (RI) manner. RI deposition of H3.3, a histone variant from the H3.3 family, is mediated in mammals by distinct pathways involving either the histone regulator A (HIRA) complex or the death-associated protein (DAXX)/α-thalassemia X-linked mental retardation protein (ATRX) complex. Here, we investigated the function of the Drosophila DAXX-like protein (DLP) by using both fly genetic approaches and protein biochemistry. DLP specifically interacts with H3.3 and shows a prominent localization on the base of the X chromosome, where it appears to act in concert with XNP, the Drosophila homolog of ATRX, in heterochromatin assembly and maintenance. The functional association between DLP and XNP is further supported by a series of experiments that illustrate genetic interactions and the DLP-XNP-dependent localization of specific chromosomal proteins. In addition, DLP both participates in the RI deposition of H3.3 and associates with anti-silencing factor 1 (ASF1). We suggest, in agreement with a recently proposed model, that DLP and ASF1 are part of a predeposition complex, which is recruited by XNP and is necessary to prevent DNA exposure in the nucleus.
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19
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Moschall R, Gaik M, Medenbach J. Promiscuity in post-transcriptional control of gene expression: Drosophila sex-lethal and its regulatory partnerships. FEBS Lett 2017; 591:1471-1488. [PMID: 28391641 PMCID: PMC5488161 DOI: 10.1002/1873-3468.12652] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/08/2017] [Accepted: 04/04/2017] [Indexed: 12/28/2022]
Abstract
The Drosophila RNA‐binding protein Sex‐lethal (Sxl) is a potent post‐transcriptional regulator of gene expression that controls female development. It regulates the expression of key factors involved in sex‐specific differences in morphology, behavior, and dosage compensation. Functional Sxl protein is only expressed in female flies, where it binds to U‐rich RNA motifs present in its target mRNAs to regulate their fate. Sxl is a very versatile regulator that, by shuttling between the nucleus and the cytoplasm, can regulate almost all aspects of post‐transcriptional gene expression including RNA processing, nuclear export, and translation. For these functions, Sxl employs multiple interactions to either antagonize RNA‐processing factors or to recruit various coregulators, thus allowing it to establish a female‐specific gene expression pattern. Here, we summarize the current knowledge about Sxl function and review recent mechanistic and structural studies that further our understanding of how such a seemingly ‘simple’ RNA‐binding protein can exert this plethora of different functions.
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Affiliation(s)
| | - Monika Gaik
- Max Planck Research Group at the Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg, Germany
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Sexual Dimorphism of Body Size Is Controlled by Dosage of the X-Chromosomal Gene Myc and by the Sex-Determining Gene tra in Drosophila. Genetics 2017; 205:1215-1228. [PMID: 28064166 PMCID: PMC5340334 DOI: 10.1534/genetics.116.192260] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 12/20/2016] [Indexed: 12/13/2022] Open
Abstract
Drosophila females are larger than males. In this article, we describe how X-chromosome dosage drives sexual dimorphism of body size through two means: first, through unbalanced expression of a key X-linked growth-regulating gene, and second, through female-specific activation of the sex-determination pathway. X-chromosome dosage determines phenotypic sex by regulating the genes of the sex-determining pathway. In the presence of two sets of X-chromosome signal elements (XSEs), Sex-lethal (Sxl) is activated in female (XX) but not male (XY) animals. Sxl activates transformer (tra), a gene that encodes a splicing factor essential for female-specific development. It has previously been shown that null mutations in the tra gene result in only a partial reduction of body size of XX animals, which shows that other factors must contribute to size determination. We tested whether X dosage directly affects animal size by analyzing males with duplications of X-chromosomal segments. Upon tiling across the X chromosome, we found four duplications that increase male size by >9%. Within these, we identified several genes that promote growth as a result of duplication. Only one of these, Myc, was found not to be dosage compensated. Together, our results indicate that both Myc dosage and tra expression play crucial roles in determining sex-specific size in Drosophila larvae and adult tissue. Since Myc also acts as an XSE that contributes to tra activation in early development, a double dose of Myc in females serves at least twice in development to promote sexual size dimorphism.
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21
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Koch L, Feicht S, Sun R, Sen A, Krahn MP. Domain-specific functions of Stardust in Drosophila embryonic development. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160776. [PMID: 28018665 PMCID: PMC5180163 DOI: 10.1098/rsos.160776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
In Drosophila, the adaptor protein Stardust is essential for the stabilization of the polarity determinant Crumbs in various epithelial tissues, including the embryonic epidermis, the follicular epithelium and photoreceptor cells of the compound eye. In turn, Stardust recruits another adaptor protein, PATJ, to the subapical region to support adherens junction formation and morphogenetic events. Moreover, Stardust binds to Lin-7, which is dispensable in epithelial cells but functions in postsynaptic vesicle fusion. Finally, Stardust has been reported to bind directly to PAR-6, thereby linking the Crumbs-Stardust-PATJ complex to the PAR-6/aPKC complex. PAR-6 and aPKC are also capable of directly binding Bazooka (the Drosophila homologue of PAR-3) to form the PAR/aPKC complex, which is essential for apical-basal polarity and cell-cell contact formation in most epithelia. However, little is known about the physiological relevance of these interactions in the embryonic epidermis of Drosophila in vivo. Thus, we performed a structure-function analysis of the annotated domains with GFP-tagged Stardust and evaluated the localization and function of the mutant proteins in epithelial cells of the embryonic epidermis. The data presented here confirm a crucial role of the PDZ domain in binding Crumbs and recruiting the protein to the subapical region. However, the isolated PDZ domain is not capable of being recruited to the cortex, and the SH3 domain is essential to support the binding to Crumbs. Notably, the conserved N-terminal regions (ECR1 and ECR2) are not crucial for epithelial polarity. Finally, the GUK domain plays an important role for the protein's function, which is not directly linked to Crumbs stabilization, and the L27N domain is essential for epithelial polarization independently of recruiting PATJ.
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Affiliation(s)
| | | | | | | | - Michael P. Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
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22
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Simon CR, Siviero F, Monesi N. Beyond DNA puffs: What can we learn from studying sciarids? Genesis 2016; 54:361-78. [PMID: 27178805 DOI: 10.1002/dvg.22946] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 11/07/2022]
Abstract
Members of the Sciaridae family attracted the interest of researchers because of the demonstration that the DNA puff regions, which are formed in the salivary gland polytene chromosomes at the end of the fourth larval instar, constitute sites of developmentally regulated gene amplification. Besides contributing to a deeper understanding of the process of gene amplification, the study of sciarids has also provided important insights on other biological processes such as sex determination, programmed cell death, insect immunity, telomere maintenance, and nucleolar organizing regions (NOR) formation. Open questions in sciarids include among others, early development, the role of noncoding RNAs in gene amplification and the relationship between gene amplification and transcription in DNA puff forming regions. These and other questions can now be pursued with next generation sequencing techniques and experiments using RNAi experiments, since this latter technique has been shown to be feasible in sciarids. These new perspectives in the field of sciarid biology open the opportunity to consolidate sciarid species as important emerging models. genesis 54:361-378, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Claudio Roberto Simon
- Departamento de Biologia Estrutural, Universidade Federal do Triângulo Mineiro-UFTM, Instituto de Ciências Biológicas e Naturais, Uberaba, MG, Brazil, CEP 38025-015
| | - Fábio Siviero
- Departamento de Biologia Celular e do Desenvolvimento, Universidade de São Paulo, Instituto de Ciências Biomédicas, São Paulo, SP, Brazil, CEP 05508-900
| | - Nadia Monesi
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Ribeirão Preto, SP, Brazil
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23
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Laohakieat K, Aketarawong N, Isasawin S, Thitamadee S, Thanaphum S. The study of the transformer gene from Bactrocera dorsalis and B. correcta with putative core promoter regions. BMC Genet 2016; 17:34. [PMID: 26833079 PMCID: PMC4736151 DOI: 10.1186/s12863-016-0342-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/25/2016] [Indexed: 12/31/2022] Open
Abstract
Background The transformer (tra) is a sex determining switch in different orders of insects, including Diptera, as in the family Tephritidae. The lifelong autoregulatory loop of tra female-specific splicing can be reset by the intervention of male-specific primary signals (M factor). In early development, the functional female and truncated male TRA proteins relay the sexual fates to the alternative splicing of a bisexual switch gene, doublesex (dsx) cascading the sexual differentiation processes. Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) are among the Bactrocera model worldwide key pests. Area-wide integrated pest management using the male-only Sterile Insect Technique (SIT) relying on genetic sexing systems is effective in control programs. We undertook the molecular characterization and comparative studies of the tra orthologues in the Bactrocera species, including the Salaya1 genetic sexing strain (GSS). Results RT-PCR revealed that B. dorsalis tra (Bdtra) and B. correcta tra (Bctra) transcripts contained conservation of both constitutive exons and male-specific exons as in other Bactrocera. However, new Bdtra male-specific exons were retained, diversifying the pattern of the male-specifically spliced transcripts. The coding sequences of tra were highly conserved in Bactrocera (86–95 %) but less so among related genera (61–65 %) within the same Tephritidae family. A conservation of deduced amino acid sequences (18 residues), called the TEP region, was identified to be distinctive among tephritids. The 5’ regulatory sequence containing many structural characteristics of the putative core promoter was discovered in B. correcta. The expression patterns of Bdtra and Bctra were sex-specifically spliced and the signals relayed to the dsx genes in the adult wild-types. However, the coexistence of male- and female-specifically spliced transcripts (980 and 626 bp, respectively) of the B. dorsalis wild-type strain was found in the Salaya1 GSS adult males. The Bdtra RNA interference masculinized the XX karyotype females into pseudomales, but their testes were mostly not well developed. Conclusions Bdtra and Bctra have sex-specific splicing, similar to Bactroceras, Ceratitis capitata (Wiedemann), and Anastrephas. A newly identified TEP region is proposed in tephritids. A putative core promoter has been discovered in Bctra. Electronic supplementary material The online version of this article (doi:10.1186/s12863-016-0342-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kamoltip Laohakieat
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Nidchaya Aketarawong
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Siriwan Isasawin
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Siripong Thitamadee
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Sujinda Thanaphum
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
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24
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Abstract
Protein depletion by genetic means, in a very general sense including the use of RNA interference [1, 2] or CRISPR/Cas9-based methods, represents a central paradigm of modern biology to study protein functions in vivo. However, acting upstream the proteic level is a limiting factor if the turnover of the target protein is slow or the existing pool of the target protein is important (for instance, in insect embryos, as a consequence of a strong maternal contribution). In order to circumvent these problems, we developed deGradFP [3, 4]. deGradFP harnesses the ubiquitin-proteasome pathway to achieve direct depletion of GFP-tagged proteins. deGradFP is in essence a universal method because it relies on an evolutionarily conserved machinery for protein catabolism in eukaryotic cells; see refs. 5, 6 for review. deGradFP is particularly convenient in Drosophila melanogaster where it is implemented by a genetically encoded effector expressed under the control of the Gal4 system. deGradFP is a ready-to-use solution to perform knockdowns at the protein level if a fly line carrying a functional GFP-tagged version of the gene of interest is available. Many such lines have already been generated by the Drosophila community through different technologies allowing to make genomic rescue constructs or direct GFP knockins: protein-trap stock collections [7, 8] ( http://cooley.medicine.yale.edu/flytrap/ , http://www.flyprot.org/ ), P[acman] system [9], MiMIC lines [10, 11], and CRISPR/Cas9-driven homologous recombination.Two essential controls of a protein knockdown experiment are easily achieved using deGradFP. First, the removal of the target protein can be assessed by monitoring the disappearance of the GFP tag by fluorescence microscopy in parallel to the documentation of the phenotype of the protein knockdown (see Note 1 ). Second, the potential nonspecific effects of deGradFP can be assessed in control fly lacking a GFP-tagged target protein. So far, no nonspecific effects of the deGradFP effector have been reported [3].
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Affiliation(s)
- Emmanuel Caussinus
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Markus Affolter
- Growth & Development, Biozentrum, University of Basel, Room 200B, Klingelbergstrasse 50/70, 4056, Basel, Switzerland.
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25
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Fu X, Li T, Chen J, Dong Y, Qiu J, Kang K, Zhang W. Functional screen for microRNAs of Nilaparvata lugens reveals that targeting of glutamine synthase by miR-4868b regulates fecundity. JOURNAL OF INSECT PHYSIOLOGY 2015; 83:22-9. [PMID: 26546713 DOI: 10.1016/j.jinsphys.2015.11.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 10/08/2015] [Accepted: 11/03/2015] [Indexed: 05/14/2023]
Abstract
Insect fecundity is regulated by the interaction of genotypes and the environment. MicroRNAs (miRNAs) also act in insect development and reproduction by regulating genes involved in these physiological processes. Although hundreds of insect miRNAs have been identified, the biological roles of most remain poorly understood. Here, we used a multi-algorithm approach for miRNA target prediction in 3'UTRs of fecundity-related genes in the brown planthopper (BPH) Nilaparvata lugens and identified 38 putative miRNAs targeting 9 fecundity-related genes. High-ranked miRNAs were selected for target validation. Using a dual luciferase reporter assay in S2 cells, we experimentally verified N. lugens glutamine synthetase (NlGS) as an authentic target of microRNA-4868b (miR-4868b). In the females, NlGS protein expression was down-regulated after injection of a miR-4868b mimic but up-regulated after injection of a miR-4868b inhibitor. In addition, overexpression of miR-4868b reduced fecundity, and disrupted ovary development and Vg expression in N. lugens. These findings showed that miR-4868b is involved in regulating N. lugens fecundity by targeting NlGS. Moreover, this study may lead to better understanding of the fecundity of this important agricultural insect pest.
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Affiliation(s)
- Xian Fu
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Tengchao Li
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Jie Chen
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yi Dong
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Jieqi Qiu
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Kui Kang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wenqing Zhang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
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Vogler G, Liu J, Iafe TW, Migh E, Mihály J, Bodmer R. Cdc42 and formin activity control non-muscle myosin dynamics during Drosophila heart morphogenesis. ACTA ACUST UNITED AC 2014; 206:909-22. [PMID: 25267295 PMCID: PMC4178965 DOI: 10.1083/jcb.201405075] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cdc42 and the formins dDAAM and Diaphanous play pivotal roles in heart lumen formation through the spatiotemporal regulation of the actomyosin network. During heart formation, a network of transcription factors and signaling pathways guide cardiac cell fate and differentiation, but the genetic mechanisms orchestrating heart assembly and lumen formation remain unclear. Here, we show that the small GTPase Cdc42 is essential for Drosophila melanogaster heart morphogenesis and lumen formation. Cdc42 genetically interacts with the cardiogenic transcription factor tinman; with dDAAM which belongs to the family of actin organizing formins; and with zipper, which encodes nonmuscle myosin II. Zipper is required for heart lumen formation, and its spatiotemporal activity at the prospective luminal surface is controlled by Cdc42. Heart-specific expression of activated Cdc42, or the regulatory formins dDAAM and Diaphanous caused mislocalization of Zipper and induced ectopic heart lumina, as characterized by luminal markers such as the extracellular matrix protein Slit. Placement of Slit at the lumen surface depends on Cdc42 and formin function. Thus, Cdc42 and formins play pivotal roles in heart lumen formation through the spatiotemporal regulation of the actomyosin network.
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Affiliation(s)
- Georg Vogler
- Development, Aging and Regeneration Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Jiandong Liu
- Development, Aging and Regeneration Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Timothy W Iafe
- Development, Aging and Regeneration Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Ede Migh
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, H-6726 Szeged, Hungary
| | - József Mihály
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, H-6726 Szeged, Hungary
| | - Rolf Bodmer
- Development, Aging and Regeneration Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
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Pomerantz AF, Hoy MA, Kawahara AY. Molecular characterization and evolutionary insights into potential sex-determination genes in the western orchard predatory miteMetaseiulus occidentalis(Chelicerata: Arachnida: Acari: Phytoseiidae). J Biomol Struct Dyn 2014; 33:1239-53. [DOI: 10.1080/07391102.2014.941402] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Male-killing Spiroplasma induces sex-specific cell death via host apoptotic pathway. PLoS Pathog 2014; 10:e1003956. [PMID: 24550732 PMCID: PMC3923752 DOI: 10.1371/journal.ppat.1003956] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 01/12/2014] [Indexed: 11/19/2022] Open
Abstract
Some symbiotic bacteria cause remarkable reproductive phenotypes like cytoplasmic incompatibility and male-killing in their host insects. Molecular and cellular mechanisms underlying these symbiont-induced reproductive pathologies are of great interest but poorly understood. In this study, Drosophila melanogaster and its native Spiroplasma symbiont strain MSRO were investigated as to how the host's molecular, cellular and morphogenetic pathways are involved in the symbiont-induced male-killing during embryogenesis. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining, anti-cleaved-Caspase-3 antibody staining, and apoptosis-deficient mutant analysis unequivocally demonstrated that the host's apoptotic pathway is involved in Spiroplasma-induced male-specific embryonic cell death. Double-staining with TUNEL and an antibody recognizing epidermal marker showed that embryonic epithelium is the main target of Spiroplasma-induced male-specific apoptosis. Immunostaining with antibodies against markers of differentiated and precursor neural cells visualized severe neural defects specifically in Spiroplasma-infected male embryos as reported in previous studies. However, few TUNEL signals were detected in the degenerate nervous tissues of male embryos, and the Spiroplasma-induced neural defects in male embryos were not suppressed in an apoptosis-deficient host mutant. These results suggest the possibility that the apoptosis-dependent epidermal cell death and the apoptosis-independent neural malformation may represent different mechanisms underlying the Spiroplasma-induced male-killing. Despite the male-specific progressive embryonic abnormality, Spiroplasma titers remained almost constant throughout the observed stages of embryonic development and across male and female embryos. Strikingly, a few Spiroplasma-infected embryos exhibited gynandromorphism, wherein apoptotic cell death was restricted to male cells. These observations suggest that neither quantity nor proliferation of Spiroplasma cells but some Spiroplasma-derived factor(s) may be responsible for the expression of the male-killing phenotype. Symbiotic bacteria are ubiquitously associated with diverse insects, and affect their host biology in a variety of ways. In Drosophila fruit flies, infection with Spiroplasma symbionts often causes male-specific embryonic mortality, resulting in the production of all-female offspring. This striking phenotype is called “male-killing”, whose underlying mechanisms are of great interest. Here we investigated Drosophila melanogaster and its native Spiroplasma symbiont strain to understand how the host's molecular, cellular and morphogenetic pathways are involved in the symbiont-induced male-killing. Specifically in Spiroplasma-infected male embryos, pathogenic phenotypes including massive cell death throughout the body and neural malformation were observed. We unequivocally identified that the male-specific cell death preferentially occurs in the embryonic epithelium via the host's apoptotic pathway. Meanwhile, we found that, unexpectedly, the male-specific neural defects occur independently of host's apoptosis, suggesting that at least two different mechanisms may be involved in the Spiroplasma-induced male-killing. Also unexpected was the finding that Spiroplasma titers are almost constant throughout embryogenesis irrespective of sex despite the male-specific severe apoptosis. We serendipitously found Spiroplasma-infected sexual mosaic embryos, wherein apoptosis was associated with male cells, which suggests that some Spiroplasma-derived factor(s) may selectively act on male cells and cause male-killing.
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Wang XY, Zheng ZZ, Song HS, Xu YZ. Conserved RNA cis-elements regulate alternative splicing of Lepidopteran doublesex. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 44:1-11. [PMID: 24239545 DOI: 10.1016/j.ibmb.2013.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/10/2013] [Accepted: 10/29/2013] [Indexed: 06/02/2023]
Abstract
Doublesex (dsx) is a downstream key regulator in insect sex determination pathway. In Drosophila, alternative splicing of Dm-dsx gene is sex-specifically regulated by transformer (tra), in which the functional TRA promotes female-specific Dm-dsx. However, the sex determination pathway in Lepidoptera is not well understood; here we focused on alternative splicing of doublesex (dsx) in two agricultural pests, Asian corn borer (Ostrinia furnacalis) and cotton bollworm (Helicoverpa armigera), as well as the silkworm (Bombyx mori). More than a dozen new alternative splicing isoforms of dsx were found in the Lepidopteran females, which exist in all tested developmental stages and differentiated tissues. Alignment of mRNA and protein sequences of doublesex revealed high conservation of this gene in Lepidoptera. Strength analysis of splice sites revealed a weak 5' splice site at intron 3 in Lepidopteran dsx, which was experimentally confirmed. Furthermore, we identified highly conserved RNA sequences in the Lepidopteran dsx, including RNA elements I (14 nt), II (11 nt), III (26 nt), IV (17 nt), 3E-1 (8 nt) and 3E-2 (8 nt). The RNA elements III and IV were previously found in exon 4 of B. mori dsx and bound with Bm-PSI, which suppressed the inclusion of exons 3 & 4 into the male-specific Bm-dsx. Then we identified and analyzed the homologous genes of Bm-psi in the two Lepidopteran pests, which expressed at similar levels and exhibited a unique isoform in the males and females from each Lepidoptera. Importantly, mutagenesis of Bm-dsx mini-genes and their expression in BmN cell line demonstrated that three RNA elements are involved in the female-specific alternative splicing of Bm-dsx. Mutations in the RNA cis-elements 3E-1 and 3E-2 resulted in decreased inclusion of exon 3 into the female-specific dsx mRNA, suggesting that these two elements would be exonic splicing enhancers that facilitate the recognition of the weak 5' splice site at intron 3 of Lepidopteran dsx. We propose that the 5' splice sites at intron 3 are weak, resulting in multiple alternative splicing events in intron 3 of female Lepidoptera dsx. Activation of the 5' splice site requires regulatory cis-elements in exons 3 for female-specific splicing of Lepidoptera dsx.
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Affiliation(s)
- Xiu-Ye Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zeng-Zhang Zheng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hong-Sheng Song
- College of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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Ruiz MF, Sarno F, Zorrilla S, Rivas G, Sánchez L. Biochemical and functional analysis of Drosophila-sciara chimeric sex-lethal proteins. PLoS One 2013; 8:e65171. [PMID: 23762307 PMCID: PMC3677924 DOI: 10.1371/journal.pone.0065171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/21/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The Drosophila SXL protein controls sex determination and dosage compensation. It is a sex-specific factor controlling splicing of its own Sxl pre-mRNA (auto-regulation), tra pre-mRNA (sex determination) and msl-2 pre-mRNA plus translation of msl-2 mRNA (dosage compensation). Outside the drosophilids, the same SXL protein has been found in both sexes so that, in the non-drosophilids, SXL does not appear to play the key discriminating role in sex determination and dosage compensation that it plays in Drosophila. Comparison of SXL proteins revealed that its spatial organisation is conserved, with the RNA-binding domains being highly conserved, whereas the N- and C-terminal domains showing significant variation. This manuscript focuses on the evolution of the SXL protein itself and not on regulation of its expression. METHODOLOGY Drosophila-Sciara chimeric SXL proteins were produced. Sciara SXL represents the non-sex-specific function of ancient SXL in the non-drosophilids from which presumably Drosophila SXL evolved. Two questions were addressed. Did the Drosophila SXL protein have affected their functions when their N- and C-terminal domains were replaced by the corresponding ones of Sciara? Did the Sciara SXL protein acquire Drosophila sex-specific functions when the Drosophila N- and C-terminal domains replaced those of Sciara? The chimeric SXL proteins were analysed in vitro to study their binding affinity and cooperative properties, and in vivo to analyse their effect on sex determination and dosage compensation by producing Drosophila flies that were transgenic for the chimeric SXL proteins. CONCLUSIONS The sex-specific properties of extant Drosophila SXL protein depend on its global structure rather than on a specific domain. This implies that the modifications, mainly in the N- and C-terminal domains, that occurred in the SXL protein during its evolution within the drosophilid lineage represent co-evolutionary changes that determine the appropriate folding of SXL to carry out its sex-specific functions.
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Affiliation(s)
- María Fernanda Ruiz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Francesca Sarno
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Silvia Zorrilla
- Instituto de Química-Física “Rocasolano”, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Germán Rivas
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Lucas Sánchez
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Birkholz O, Rickert C, Berger C, Urbach R, Technau GM. Neuroblast pattern and identity in the Drosophila tail region and role of doublesex in the survival of sex-specific precursors. Development 2013; 140:1830-42. [PMID: 23533181 DOI: 10.1242/dev.090043] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The central nervous system is composed of segmental units (neuromeres), the size and complexity of which evolved in correspondence to their functional requirements. In Drosophila, neuromeres develop from populations of neural stem cells (neuroblasts) that delaminate from the early embryonic neuroectoderm in a stereotyped spatial and temporal pattern. Pattern units closely resemble the ground state and are rather invariant in thoracic (T1-T3) and anterior abdominal (A1-A7) segments of the embryonic ventral nerve cord. Here, we provide a comprehensive neuroblast map of the terminal abdominal neuromeres A8-A10, which exhibit a progressively derived character. Compared with thoracic and anterior abdominal segments, neuroblast numbers are reduced by 28% in A9 and 66% in A10 and are almost entirely absent in the posterior compartments of these segments. However, all neuroblasts formed exhibit serial homology to their counterparts in more anterior segments and are individually identifiable based on their combinatorial code of marker gene expression, position, delamination time point and the presence of characteristic progeny cells. Furthermore, we traced the embryonic origin and characterised the postembryonic lineages of a set of terminal neuroblasts, which have been previously reported to exhibit sex-specific proliferation behaviour during postembryonic development. We show that the respective sex-specific product of the gene doublesex promotes programmed cell death of these neuroblasts in females, and is needed for their survival, but not proliferation, in males. These data establish the terminal neuromeres as a model for further investigations into the mechanisms controlling segment- and sex-specific patterning in the central nervous system.
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Nakazawa N, Taniguchi K, Okumura T, Maeda R, Matsuno K. A novel Cre/loxP system for mosaic gene expression in the Drosophila embryo. Dev Dyn 2012; 241:965-74. [PMID: 22437963 DOI: 10.1002/dvdy.23784] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Mosaic analysis is used to assess gene function and cell autonomy in a subset of cells in an organism, and has been extensively applied in Drosophila studies. However, it is difficult to generate mosaic cells in Drosophila embryonic tissues using existing methods. Therefore, we developed a new method for generating genetic mosaic embryos using a modified Cre/loxP system. In this report, we also characterized the capabilities and limitations of this novel method. RESULTS We first constructed a novel cassette combining loxP with the Actin 5C enhancer and Gal4 cDNA, and generated a transgenic fly carrying this construct (Aloxg-Gal4). In Aloxg-Gal4, the activation of Gal4 expression is suppressed by the gypsy insulator. Once the gypsy insulator is removed, however, Gal4 is expressed when site-specific recombination between loxP sites is induced by Cre recombinase. This system allowed the mosaic expression of Gal4 in Drosophila embryonic tissues (epidermis, amnioserosa, tracheal system, malpighian tubules, foregut, hindgut, midgut, and neuron), leading to the Gal4-dependent activation of arbitrary genes under the control of the upstream activation sequence (UAS). CONCLUSIONS This practical method can be used to generate mosaic cells in Drosophila embryonic tissues and can be applied to any gene without specialized equipment.
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Affiliation(s)
- Naotaka Nakazawa
- Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, Japan
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Lahaye LL, Wouda RR, de Jong AWM, Fradkin LG, Noordermeer JN. WNT5 interacts with the Ryk receptors doughnut and derailed to mediate muscle attachment site selection in Drosophila melanogaster. PLoS One 2012; 7:e32297. [PMID: 22403643 PMCID: PMC3293800 DOI: 10.1371/journal.pone.0032297] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 01/24/2012] [Indexed: 01/12/2023] Open
Abstract
In recent years a number of the genes that regulate muscle formation and maintenance in higher organisms have been identified. Studies employing invertebrate and vertebrate model organisms have revealed that many of the genes required for early mesoderm specification are highly conserved throughout evolution. Less is known about the molecules that mediate the steps subsequent to myogenesis, e. g. myotube guidance and attachment to tendon cells. We use the stereotypic pattern of the Drosophila embryonic body wall musculature in genetic approaches to identify novel factors required for muscle attachment site selection. Here, we show that Wnt5 is needed in this process. The lateral transverse muscles frequently overshoot their target attachment sites and stably attach at novel epidermal sites in Wnt5 mutant embryos. Restoration of WNT5 expression in either the muscle or the tendon cell rescues the mutant phenotype. Surprisingly, the novel attachment sites in Wnt5 mutants frequently do not express the Stripe (SR) protein which has been shown to be required for terminal tendon cell differentiation. A muscle bypass phenotype was previously reported for embryos lacking the WNT5 receptor Derailed (DRL). drl and Wnt5 mutant embryos also exhibit axon path finding errors. DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins. We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype. Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection. These results extend previous findings that at least some of the molecular pathways that guide axons towards their targets are also employed for guidance of muscle fibers to their appropriate attachment sites.
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Affiliation(s)
| | | | | | - Lee G. Fradkin
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail: (JNN); (LGF)
| | - Jasprina N. Noordermeer
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail: (JNN); (LGF)
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Riparbelli MG, Giordano R, Ueyama M, Callaini G. Wolbachia-mediated male killing is associated with defective chromatin remodeling. PLoS One 2012; 7:e30045. [PMID: 22291901 PMCID: PMC3264553 DOI: 10.1371/journal.pone.0030045] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 12/08/2011] [Indexed: 11/19/2022] Open
Abstract
Male killing, induced by different bacterial taxa of maternally inherited microorganisms, resulting in highly distorted female-biased sex-ratios, is a common phenomenon among arthropods. Some strains of the endosymbiont bacteria Wolbachia have been shown to induce this phenotype in particular insect hosts. High altitude populations of Drosophila bifasciata infected with Wolbachia show selective male killing during embryonic development. However, since this was first reported, circa 60 years ago, the interaction between Wolbachia and its host has remained unclear. Herein we show that D. bifasciata male embryos display defective chromatin remodeling, improper chromatid segregation and chromosome bridging, as well as abnormal mitotic spindles and gradual loss of their centrosomes. These defects occur at different times in the early development of male embryos leading to death during early nuclear division cycles or large defective areas of the cellular blastoderm, culminating in abnormal embryos that die before eclosion. We propose that Wolbachia affects the development of male embryos by specifically targeting male chromatin remodeling and thus disturbing mitotic spindle assembly and chromosome behavior. These are the first observations that demonstrate fundamental aspects of the cytological mechanism of male killing and represent a solid base for further molecular studies of this phenomenon.
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Affiliation(s)
| | - Rosanna Giordano
- Illinois Natural History Survey, Institute of Natural Resource Sustainability, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America
| | - Morio Ueyama
- Laboratory of Cell Biology, Department of Bioinformatics, Soka University, Hachioji, Tokyo, Japan
| | - Giuliano Callaini
- Department of Evolutionary Biology, University of Siena, Siena, Italy
- * E-mail:
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Yamakawa T, Yamada K, Sasamura T, Nakazawa N, Kanai M, Suzuki E, Fortini ME, Matsuno K. Deficient Notch signaling associated with neurogenic pecanex is compensated for by the unfolded protein response in Drosophila. Development 2011; 139:558-67. [PMID: 22190636 DOI: 10.1242/dev.073858] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The Notch (N) signaling machinery is evolutionarily conserved and regulates a broad spectrum of cell-specification events, through local cell-cell communication. pecanex (pcx) encodes a multi-pass transmembrane protein of unknown function, widely found from Drosophila to humans. The zygotic and maternal loss of pcx in Drosophila causes a neurogenic phenotype (hyperplasia of the embryonic nervous system), suggesting that pcx might be involved in N signaling. Here, we established that Pcx is a component of the N-signaling pathway. Pcx was required upstream of the membrane-tethered and the nuclear forms of activated N, probably in N signal-receiving cells, suggesting that pcx is required prior to or during the activation of N. pcx overexpression revealed that Pcx resides in the endoplasmic reticulum (ER). Disruption of pcx function resulted in enlargement of the ER that was not attributable to the reduced N signaling activity. In addition, hyper-induction of the unfolded protein response (UPR) by the expression of activated Xbp1 or dominant-negative Heat shock protein cognate 3 suppressed the neurogenic phenotype and ER enlargement caused by the absence of pcx. A similar suppression of these phenotypes was induced by overexpression of O-fucosyltransferase 1, an N-specific chaperone. Taking these results together, we speculate that the reduction in N signaling in embryos lacking pcx function might be attributable to defective ER functions, which are compensated for by upregulation of the UPR and possibly by enhancement of N folding. Our results indicate that the ER plays a previously unrecognized role in N signaling and that this ER function depends on pcx activity.
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Affiliation(s)
- Tomoko Yamakawa
- Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510 Japan
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Hashiyama K, Hayashi Y, Kobayashi S. Drosophila Sex lethal gene initiates female development in germline progenitors. Science 2011; 333:885-8. [PMID: 21737698 DOI: 10.1126/science.1208146] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Sex determination in the Drosophila germ line is regulated by both the sex of the surrounding soma and cell-autonomous cues. How primordial germ cells (PGCs) initiate sexual development via cell-autonomous mechanisms is unclear. Here, we demonstrate that, in Drosophila, the Sex lethal (Sxl) gene acts autonomously in PGCs to induce female development. Sxl is transiently expressed in PGCs during their migration to the gonads; this expression, which was detected only in XX PGCs, is necessary for PGCs to assume a female fate. Ectopic expression of Sxl in XY PGCs was sufficient to induce them to enter oogenesis and produce functional eggs when transplanted into an XX host. Our data provide powerful evidence that Sxl initiates female germline fate during sexual development.
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Affiliation(s)
- Kazuya Hashiyama
- Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
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Sugimoto TN, Fujii T, Kayukawa T, Sakamoto H, Ishikawa Y. Expression of a doublesex homologue is altered in sexual mosaics of Ostrinia scapulalis moths infected with Wolbachia. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2010; 40:847-854. [PMID: 20728536 DOI: 10.1016/j.ibmb.2010.08.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 08/11/2010] [Accepted: 08/12/2010] [Indexed: 05/29/2023]
Abstract
A homologue of the sex-determining gene doublesex, Osdsx, was identified in the adzuki bean borer Ostrinia scapulalis. Three isoforms of the Osdsx transcript (Osdsx(M), Osdsx(FL) and Osdsx(FS)) differing in length were found. Osdsx(M) was specifically found in males, and contained an 852-bp ORF encoding a protein of 284 amino acids. Osdsx(FL) and Osdsx(FS) were found in females, and had the same 813-bp ORF encoding a protein of 271 amino acids. The Osdsx gene was inferred to have six exons and five introns. The variation in the transcript could be explained by the alternative splicing of Osdsx: Osdsx(M) was formed by the splicing of exons 1, 2, 5 and 6, Osdsx(FS) by the splicing of exons 1-4 and 6, and Osdsx(FL) by the splicing of exons 1-6. RT-PCR analysis indicated that Osdsx was transcribed in a sex-specific manner in all somatic tissues examined, regardless of developmental stage. In Wolbachia-induced sexual mosaics of O. scapulalis, which are genetically male, the female-specific isoform of Osdsx (Osdsx(FL)) was shown to be expressed in addition to the male-specific isoform (Osdsx(M)). This finding provides the first evidence that Wolbachia manipulates the sex of its host by interfering either with the sex-specific splicing of Osdsx itself or with another upstream sex determination process.
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Affiliation(s)
- Takafumi N Sugimoto
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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Abstract
In Drosophila melanogaster, the gene Sex-lethal (Sxl) controls all aspects of female development. Since melanogaster males lacking Sxl appear wild type, Sxl would seem to be functionally female specific. Nevertheless, in insects as diverse as honeybees and houseflies, Sxl seems not to determine sex or to be functionally female specific. Here we describe three lines of work that address the questions of how, when, and even whether the ancestor of melanogaster Sxl ever shed its non-female-specific functions. First, to test the hypothesis that the birth of Sxl's closest paralog allowed Sxl to lose essential ancestral non-female-specific functions, we determined the CG3056 null phenotype. That phenotype failed to support this hypothesis. Second, to define when Sxl might have lost ancestral non-female-specific functions, we isolated and characterized Sxl mutations in D. virilis, a species distant from melanogaster and notable for the large amount of Sxl protein expression in males. We found no change in Sxl regulation or functioning in the 40+ MY since these two species diverged. Finally, we discovered conserved non-sex-specific Sxl mRNAs containing a previously unknown, potentially translation-initiating exon, and we identified a conserved open reading frame starting in Sxl male-specific exon 3. We conclude that Drosophila Sxl may appear functionally female specific not because it lost non-female-specific functions, but because those functions are nonessential in the laboratory. The potential evolutionary relevance of these nonessential functions is discussed.
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Shukla JN, Jadhav S, Nagaraju J. Novel female-specific splice form of dsx in the silkworm, Bombyx mori. Genetica 2010; 139:23-31. [PMID: 20714790 DOI: 10.1007/s10709-010-9479-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 07/29/2010] [Indexed: 11/28/2022]
Abstract
The Bombyx mori doublesex (Bmdsx), a homologue of doublesex of Drosophila, is the bottom most gene of the sex determination cascade. Bmdsx plays a very crucial role in somatic sexual development. Its pre-mRNA sex-specifically splices to generate two splice variants; one encodes female-specific and the other encodes male-specific polypeptides which differ only at their C-termini. The open reading frame of Bmdsx consists of 5 exons, of which exons 3 and 4 are female-specific and are skipped in males. In the present study, we have identified a third splice form of the Bmdsx which is specific only to females and differs from the previously reported Bmdsxf isoform by the presence of 15 bp sequence. This new female splice form is generated as a result of alternative 5' splice site selection in the third exon adding additional 15 bp sequence in exon 3 which results in alteration of the reading frame leading to incorporation of an early stop codon. Thus the protein encoded by this splice form is 20 aa shorter than the known BmDsxF. Initial results obtained from the study of dsx homologues in Saturniid silkmoths suggest that both the female-specific Dsx proteins are essential for female sexual differentiation. It remains to be seen whether female-specific multiple splice forms of dsx are characteristic feature of only silkmoths or widespread among lepidopterans. The findings that sex determination mechanism is unique in lepidopterans offer an opportunity to develop genetic sexing methods in beneficial as well as economically destructive lepidopteran pests.
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Affiliation(s)
- Jayendra Nath Shukla
- Centre of Excellence for Genetics and Genomics of Silkmoths, Laboratory of Molecular Genetics, Centre for DNA Fingerprinting and Diagnostics, Tuljaguda, Nampally, Hyderabad, 500001, India
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Robinett CC, Vaughan AG, Knapp JM, Baker BS. Sex and the single cell. II. There is a time and place for sex. PLoS Biol 2010; 8:e1000365. [PMID: 20454565 PMCID: PMC2864297 DOI: 10.1371/journal.pbio.1000365] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 03/25/2010] [Indexed: 01/28/2023] Open
Abstract
In both male and female Drosophila, only a subset of cells have the potential to sexually differentiate, making both males and females mosaics of sexually differentiated and sexually undifferentiated cells. The Drosophila melanogaster sex hierarchy controls sexual differentiation of somatic cells via the activities of the terminal genes in the hierarchy, doublesex (dsx) and fruitless (fru). We have targeted an insertion of GAL4 into the dsx gene, allowing us to visualize dsx-expressing cells in both sexes. Developmentally and as adults, we find that both XX and XY individuals are fine mosaics of cells and tissues that express dsx and/or fruitless (fruM), and hence have the potential to sexually differentiate, and those that don't. Evolutionary considerations suggest such a mosaic expression of sexuality is likely to be a property of other animal species having two sexes. These results have also led to a major revision of our view of how sex-specific functions are regulated by the sex hierarchy in flies. Rather than there being a single regulatory event that governs the activities of all downstream sex determination regulatory genes—turning on Sex lethal (Sxl) RNA splicing activity in females while leaving it turned off in males—there are, in addition, elaborate temporal and spatial transcriptional controls on the expression of the terminal regulatory genes, dsx and fru. Thus tissue-specific aspects of sexual development are jointly specified by post-transcriptional control by Sxl and by the transcriptional controls of dsx and fru expression. Morphologically, fruit flies are either male or female. The specification of sex is a multi-step process that depends on whether the fertilized egg has only one X chromosome (will develop as male) or two X chromosomes (will develop as female). This initial assessment of sex activates a cascade of regulatory genes that ultimately results in expression of either the male or female version of the protein encoded by the doublesex gene (dsx). These sex-specific proteins from the dsx gene direct most aspects of somatic sexual development, including the development of all of the secondary sexual characteristics that visibly distinguish males and females. In flies, as in most animal species, only some tissues are obviously different between the two sexes, so we asked the question of whether all cells in the animal nevertheless know which sex they are. That is, do all cells express dsx? We have developed a genetic tool that lets us visualize the cells in which the dsx is expressed. Strikingly, dsx is only expressed in a subset of tissues. Thus, adult flies of both sexes appear to be mosaics of cells that do know their sex and cells that do not know their sex.
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Affiliation(s)
- Carmen C. Robinett
- Biology Department, Stanford University, Stanford, California, United States of America
| | - Alexander G. Vaughan
- Biology Department, Stanford University, Stanford, California, United States of America
| | - Jon-Michael Knapp
- Biology Department, Stanford University, Stanford, California, United States of America
- Neuroscience Program, Stanford University, Stanford, California, United States of America
| | - Bruce S. Baker
- Biology Department, Stanford University, Stanford, California, United States of America
- Neuroscience Program, Stanford University, Stanford, California, United States of America
- * E-mail:
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Johnson ML, Nagengast AA, Salz HK. PPS, a large multidomain protein, functions with sex-lethal to regulate alternative splicing in Drosophila. PLoS Genet 2010; 6:e1000872. [PMID: 20221253 PMCID: PMC2832672 DOI: 10.1371/journal.pgen.1000872] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 02/03/2010] [Indexed: 12/25/2022] Open
Abstract
Alternative splicing controls the expression of many genes, including the Drosophila sex determination gene Sex-lethal (Sxl). Sxl expression is controlled via a negative regulatory mechanism where inclusion of the translation-terminating male exon is blocked in females. Previous studies have shown that the mechanism leading to exon skipping is autoregulatory and requires the SXL protein to antagonize exon inclusion by interacting with core spliceosomal proteins, including the U1 snRNP protein Sans-fille (SNF). In studies begun by screening for proteins that interact with SNF, we identified PPS, a previously uncharacterized protein, as a novel component of the machinery required for Sxl male exon skipping. PPS encodes a large protein with four signature motifs, PHD, BRK, TFS2M, and SPOC, typically found in proteins involved in transcription. We demonstrate that PPS has a direct role in Sxl male exon skipping by showing first that loss of function mutations have phenotypes indicative of Sxl misregulation and second that the PPS protein forms a complex with SXL and the unspliced Sxl RNA. In addition, we mapped the recruitment of PPS, SXL, and SNF along the Sxl gene using chromatin immunoprecipitation (ChIP), which revealed that, like many other splicing factors, these proteins bind their RNA targets while in close proximity to the DNA. Interestingly, while SNF and SXL are specifically recruited to their predicted binding sites, PPS has a distinct pattern of accumulation along the Sxl gene, associating with a region that includes, but is not limited to, the SxlPm promoter. Together, these data indicate that PPS is different from other splicing factors involved in male-exon skipping and suggest, for the first time, a functional link between transcription and SXL-mediated alternative splicing. Loss of zygotic PPS function, however, is lethal to both sexes, indicating that its role may be of broad significance.
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Affiliation(s)
- Matthew L. Johnson
- Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, Ohio, United States of America
| | - Alexis A. Nagengast
- Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, Ohio, United States of America
| | - Helen K. Salz
- Department of Genetics, Case Western Reserve University, School of Medicine, Cleveland, Ohio, United States of America
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Abstract
One of the most important decisions in development is whether to be male or female. In Drosophila melanogaster, most cells make this choice independent of their neighbors such that diploid cells with one X chromosome (XY) are male and those with two X chromosomes (XX) are female. X-chromosome number is relayed through regulatory proteins that act together to activate Sex-lethal (Sxl) in XX animals. The resulting SXL female specific RNA binding protein modulates the expression of a set of downstream genes, ultimately leading to sexually dimorphic structures and behaviors. Despite the apparent simplicity of this mechanism, Sxl activity is controlled by a host of transcriptional and posttranscriptional mechanisms that tailor its function to specific developmental scenarios. This review describes recent advances in our understanding of Sxl regulation and function, highlighting work that challenges some of the textbook views about this classical (often cited, yet poorly understood) binary switch gene.
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Affiliation(s)
- Helen K Salz
- Department of Genetics, Case Western Reserve University, Cleveland, OH, USA.
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Hu J, Cui G, Li C, Liu C, Shang E, Lai L, Jin C, Wang J, Xia B. Structure and novel functional mechanism of Drosophila SNF in sex-lethal splicing. PLoS One 2009; 4:e6890. [PMID: 19727396 PMCID: PMC2731243 DOI: 10.1371/journal.pone.0006890] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Accepted: 07/29/2009] [Indexed: 11/18/2022] Open
Abstract
Sans-fille (SNF) is the Drosophila homologue of mammalian general splicing factors U1A and U2B'', and it is essential in Drosophila sex determination. We found that, besides its ability to bind U1 snRNA, SNF can also bind polyuridine RNA tracts flanking the male-specific exon of the master switch gene Sex-lethal (Sxl) pre-mRNA specifically, similar to Sex-lethal protein (SXL). The polyuridine RNA binding enables SNF directly inhibit Sxl exon 3 splicing, as the dominant negative mutant SNF(1621) binds U1 snRNA but not polyuridine RNA. Unlike U1A, both RNA recognition motifs (RRMs) of SNF can recognize polyuridine RNA tracts independently, even though SNF and U1A share very high sequence identity and overall structure similarity. As SNF RRM1 tends to self-associate on the opposite side of the RNA binding surface, it is possible for SNF to bridge the formation of super-complexes between two introns flanking Sxl exon 3 or between a intron and U1 snRNP, which serves the molecular basis for SNF to directly regulate Sxl splicing. Taken together, a new functional model for SNF in Drosophila sex determination is proposed. The key of the new model is that SXL and SNF function similarly in promoting Sxl male-specific exon skipping with SNF being an auxiliary or backup to SXL, and it is the combined dose of SXL and SNF governs Drosophila sex determination.
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Affiliation(s)
- Jicheng Hu
- Beijing Nuclear Magnetic Resonance Center, Beijing, People's Republic of China
- College of Life Sciences, Peking University, Beijing, People's Republic of China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Gaofeng Cui
- Beijing Nuclear Magnetic Resonance Center, Beijing, People's Republic of China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Congmin Li
- Beijing Nuclear Magnetic Resonance Center, Beijing, People's Republic of China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Cong Liu
- College of Life Sciences, Peking University, Beijing, People's Republic of China
| | - Erchang Shang
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Luhua Lai
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, Beijing, People's Republic of China
- College of Life Sciences, Peking University, Beijing, People's Republic of China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
| | - Jiwu Wang
- Allele Biotechnology & Pharmaceuticals, Inc., San Diego, California, United States of America
- * E-mail: (BX); (JW)
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, Beijing, People's Republic of China
- College of Life Sciences, Peking University, Beijing, People's Republic of China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China
- * E-mail: (BX); (JW)
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Sex-lethal facilitates the transition from germline stem cell to committed daughter cell in the Drosophila ovary. Genetics 2009; 182:121-32. [PMID: 19237687 DOI: 10.1534/genetics.109.100693] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Drosophila, the female-specific SEX-LETHAL (SXL) protein is required for oogenesis, but how Sxl interfaces with the genetic circuitry controlling oogenesis remains unknown. Here we use an allele of sans fille (snf) that specifically eliminates SXL protein in germ cells to carry out a detailed genetic and cell biological analysis of the resulting ovarian tumor phenotype. We find that tumor growth requires both Cyclin B and zero population growth, demonstrating that these mutant cells retain at least some of the essential growth-control mechanisms used by wild-type germ cells. Using a series of molecular markers, we establish that while the tumor often contains at least one apparently bona fide germline stem cell, the majority of cells exhibit an intermediate fate between a stem cell and its daughter cell fated to differentiate. In addition, snf tumors misexpress a select group of testis-enriched markers, which, remarkably, are also misexpressed in ovarian tumors that arise from the loss of bag of marbles (bam). Results of genetic epistasis experiments further reveal that bam's differentiation-promoting function depends on Sxl. Together these data demonstrate a novel role for Sxl in the lineage progression from stem cell to committed daughter cell and suggest a model in which Sxl partners with bam to facilitate this transition.
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Erickson JW, Quintero JJ. Indirect effects of ploidy suggest X chromosome dose, not the X:A ratio, signals sex in Drosophila. PLoS Biol 2008; 5:e332. [PMID: 18162044 PMCID: PMC2222971 DOI: 10.1371/journal.pbio.0050332] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Accepted: 11/09/2007] [Indexed: 11/18/2022] Open
Abstract
In the textbook view, the ratio of X chromosomes to autosome sets, X:A, is the primary signal specifying sexual fate in Drosophila. An alternative idea is that X chromosome number signals sex through the direct actions of several X-encoded signal element (XSE) proteins. In this alternative, the influence of autosome dose on X chromosome counting is largely indirect. Haploids (1X;1A), which possess the male number of X chromosomes but the female X:A of 1.0, and triploid intersexes (XX;AAA), which possess a female dose of two X chromosomes and the ambiguous X:A ratio of 0.67, represent critical tests of these hypotheses. To directly address the effects of ploidy in primary sex determination, we compared the responses of the signal target, the female-specific SxlPe promoter of the switch gene Sex-lethal, in haploid, diploid, and triploid embryos. We found that haploids activate SxlPe because an extra precellular nuclear division elevates total X chromosome numbers and XSE levels beyond those in diploid males. Conversely, triploid embryos cellularize one cycle earlier than diploids, causing premature cessation of SxlPe expression. This prevents XX;AAA embryos from fully engaging the autoregulatory mechanism that maintains subsequent Sxl expression, causing them to develop as sexual mosaics. We conclude that the X:A ratio predicts sexual fate, but does not actively specify it. Instead, the instructive X chromosome signal is more appropriately seen as collective XSE dose in the early embryo. Our findings reiterate that correlations between X:A ratios and cell fates in other organisms need not implicate the value of the ratio as an active signal.
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Affiliation(s)
- James W Erickson
- Department of Biology, Texas A&M University, College Station, Texas, United States of America.
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Hempel LU, Oliver B. Sex-specific DoublesexM expression in subsets of Drosophila somatic gonad cells. BMC DEVELOPMENTAL BIOLOGY 2007; 7:113. [PMID: 17935627 PMCID: PMC2148063 DOI: 10.1186/1471-213x-7-113] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 10/12/2007] [Indexed: 12/02/2022]
Abstract
Background In Drosophila melanogaster, a pre-mRNA splicing hierarchy controls sexual identity and ultimately leads to sex-specific Doublesex (DSX) transcription factor isoforms. The male-specific DSXM represses genes involved in female development and activates genes involved in male development. Spatial and temporal control of dsx during embryogenesis is not well documented. Results Here we show that DSXM is specifically expressed in subsets of male somatic gonad cells during embryogenesis. Following testis formation, germ cells remain in contact with DSXM-expressing cells, including hub cells and premeiotic somatic cyst cells that surround germ cells during spermatogenesis in larval and adult testes. Conclusion We show that dsx is transcriptionally regulated in addition to being regulated at the pre-mRNA splicing level by the sex determination hierarchy. The dsx locus is spatially controlled by somatic gonad identity. The continuous expression of DSXM in cells contacting the germline suggests an ongoing short-range influence of the somatic sex determination pathway on germ cell development.
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Affiliation(s)
- Leonie U Hempel
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, 50 South Drive, Bethesda MD 20892 USA.
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Mahowald AP, Wei G. Sex determination of germ cells in Drosophila. CIBA FOUNDATION SYMPOSIUM 2007; 182:193-202; discussion 202-9. [PMID: 7835150 DOI: 10.1002/9780470514573.ch11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Many lines of evidence indicate that in Drosophila the mechanism for establishing the sex of the female germline is different from that acting in somatic cells. In the soma Sxl has an embryonic determinative role and is required throughout the life of female flies; in germ cells its expression begins only in the larval ovary. Both the mechanism for activating Sxl and the genes controlled by Sxl are different in the germline. A number of genes have been identified that are essential either for survival (e.g. ovo, otu) or differentiation (snf, Sxl, fl(2)d, bgcn) of female germ cells. ovo is required during embryogenesis for survival of pole cells. Genetic interactions with dominant alleles of ovo and/or Sxl indicate that otu, Sxl, snf and fl(2)d act in the same pathway as does ovo. bgcn differs in that neither ovo nor SxlD mutations affect the bgcn phenotype even though XX bgcn germ cells enter the male pathway. bgcn causes sterility in both sexes. Although the germline defect is cell autonomous in mosaic gonads, bgcn is also required in the somatic tissue for maintaining oogenesis of wild-type germ cells. Several dominant suppressors of bgcn have been identified and some have properties similar to Suppressors of variegation, suggesting that chromatin structure is critical for proper germ cell sex determination.
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Affiliation(s)
- A P Mahowald
- Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637
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Bentley JK, Veneti Z, Heraty J, Hurst GDD. The pathology of embryo death caused by the male-killing Spiroplasma bacterium in Drosophila nebulosa. BMC Biol 2007; 5:9. [PMID: 17362512 PMCID: PMC1832177 DOI: 10.1186/1741-7007-5-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 03/15/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Inherited bacteria that kill male offspring, male-killers, are known to be common in insects, but little is understood about the mechanisms used by male-killing bacteria to kill males. In this paper we describe the tempo and changes that occur during male-killing by Spiroplasma bacteria in the host Drosophila nebulosa. RESULTS Spiroplasma infected D. nebulosa males were developmentally retarded from 6-8 h into embryonic development at 25 degrees C, and arrested at between stages 12 and 13 of embryogenesis (10-12 h). Dying males were characterized by a failure to form segments, and ultimately disintegration of the normal oval embryonic shape. Prior to death, dying males exhibited widespread apoptosis, as testified by TUNEL staining. CONCLUSION The Spiroplasma kills male Drosophila in a narrow developmental period, shortly after the formation of the host dosage compensation complex that is required for male-killing. Male death is preceded by widespread apoptosis, but it is uncertain if this is primary or secondary apoptosis.
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Affiliation(s)
- Joanna K Bentley
- Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK
| | - Zoe Veneti
- Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK
| | - Joseph Heraty
- Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK
| | - Gregory DD Hurst
- Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK
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Yamamoto D. The neural and genetic substrates of sexual behavior in Drosophila. ADVANCES IN GENETICS 2007; 59:39-66. [PMID: 17888794 DOI: 10.1016/s0065-2660(07)59002-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
fruitless (fru), originally identified with its mutant conferring male homosexuality, is a neural sex determination gene in Drosophila that produces sexually dimorphic sets of transcripts. In the nervous system, Fru is translated only in males. Fru proteins likely regulate the transcription of a set of downstream genes. The expression of Fru proteins is sufficient to induce male sexual behavior in females. A group of fru-expressing neurons called "mAL" neurons in the brain shows conspicuous sexual dimorphism. mAL is composed of 5 neurons in females and 30 neurons in males. It includes neurons with bilateral projections in males and contralateral projections in females. Terminal arborization patterns are also sexually dimorphic. These three characteristics are feminized in fru mutant males. The inactivation of cell death genes results in the production of additional mAL neurons that are of the male type in the female brain. This suggests that male-specific Fru inhibits mAL neuron death, leading to the formation of a male-specific neural circuit that underlies male sexual behavior. Fru orchestrates a spectrum of downstream genes as a master control gene to establish the maleness of the brain.
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Affiliation(s)
- Daisuke Yamamoto
- Division of Neurogenetics, Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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Vanderzwan-Butler CJ, Prazak LM, Gergen JP. The HMG-box protein Lilliputian is required for Runt-dependent activation of the pair-rule gene fushi-tarazu. Dev Biol 2006; 301:350-60. [PMID: 17137570 DOI: 10.1016/j.ydbio.2006.10.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 09/06/2006] [Accepted: 10/19/2006] [Indexed: 10/24/2022]
Abstract
lilliputian (lilli), the sole Drosophila member of the FMR2/AF4 (Fragile X Mental Retardation/Acute Lymphoblastic Leukemia) family of transcription factors, is widely expressed with roles in segmentation, cellularization, and gastrulation during early embryogenesis with additional distinct roles at later stages of embryonic and postembryonic development. We identified lilli in a genetic screen based on the suppression of a lethal phenotype that is associated with ectopic expression of the transcription factor encoded by the segmentation gene runt in the blastoderm embryo. In contrast to other factors identified by this screen, lilli appears to have no role in mediating either the establishment or maintenance of engrailed (en) repression by Runt. Instead, we find that Lilli plays a critical role in the Runt-dependent activation of the pair-rule segmentation gene fushi-tarazu (ftz). The requirement for lilli is distinct from and temporally precedes the Runt-dependent activation of ftz that is mediated by the orphan nuclear receptor protein Ftz-F1. We further describe a role for lilli in the activation of Sex-lethal (Sxl), an early target of Runt in the sex determination pathway. However, lilli is not required for all targets that are activated by Runt and appears to have no role in activation of sloppy paired (slp1). Based on these results we suggest that Lilli plays an architectural role in facilitating transcriptional activation that depends both on the target gene and the developmental context.
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Affiliation(s)
- Christine J Vanderzwan-Butler
- Department of Biochemistry and Cell Biology and the Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5140, USA; Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794-5140, USA
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