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Zhen C, Yang H, Luo S, Huang J, Wu J. Broad-complex Z3 contributes to the ecdysone-mediated transcriptional regulation of the vitellogenin gene in Bombus lantschouensis. PLoS One 2018; 13:e0207275. [PMID: 30440013 PMCID: PMC6237364 DOI: 10.1371/journal.pone.0207275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/29/2018] [Indexed: 01/03/2023] Open
Abstract
During reproduction, vitellogenin (Vg), as an egg yolk precursor, is critical in sexually mature females of oviparous species including some insects. The transcription of Vg is usually mediated by hormones such as juvenile hormone (JH), ecdysteroids and some neuropeptides. In this study, the structure of the Vg gene from the bumblebee Bombus lantschouensis, (BlVg) was determined by sequencing and assembly. BlVg was found to be expressed at higher levels in reproductive queens than in virgins by quantitative real-time PCR analysis. Tissue-specific expression analysis showed that BlVg was expressed at the highest levels in the fat bodies of both virgin and reproductive queens. Prediction of the BlVg promoter revealed the presence of ecdysteroid-responsive cis-regulatory elements (CREs) containing one Broad-Complex zinc-finger isoform 3 (BR-C Z3), and one ecdysone-induced protein 74A (E74A). In addition, luciferase reporter expression, driven by the 5' -regulatory region of the BlVg gene, from -1517 bp to +895 bp downstream of the start codon, was induced by treatment with 20-hydroxyecdysone (20-E). Moreover, the luciferase activity of the BlVg promoter was elevated by only BlBrC-Z3 when Sf9 cells were cotransfected with four BlBrC isoforms respectively. BlVg promoter-mediated luciferase activation was significantly reduced when the putative BrC-Z3 CRE in the promoter was mutated. In summary, this report describes the first study of vitellogenin gene regulation at the transcriptional level in bumblebees and demonstrates that the ecdysone-induced transcription of the BlVg gene is mediated by the binding of BlBrC-Z3 to the BrC-Z3 CRE in the BlVg promoter in bumblebees.
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Affiliation(s)
- Congai Zhen
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Huipeng Yang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Shudong Luo
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
| | - Jiaxing Huang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
| | - Jie Wu
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, PR China
- * E-mail: (JW); (JH)
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VenkatRao V, Chaitanya RK, Dutta-Gupta A. 20-hydroxyecdysone mediates fat body arylphorin regulation during development of rice moth, Corcyra cephalonica. Gene 2016; 575:747-54. [PMID: 26456107 DOI: 10.1016/j.gene.2015.09.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/03/2015] [Accepted: 09/23/2015] [Indexed: 11/27/2022]
Abstract
Arylphorin hexamerins are one of the major insect storage proteins involved in diverse functions during metamorphosis. However, their regulation during development is not elucidated so far. In the present study, we documented 20-hydroxyecdysone (20E)-mediated regulation of arylphorin expression in the fat body of the stored grain pest, Corcyra cephalonica. Based on the differential developmental expression and 20E-induced transcriptional as well as translational level alterations of arylphorin, we isolated the 5' upstream region of the gene to analyze regulatory motifs. Promoter motif analysis revealed the presence of ecdysone response element (ERE). Transient transfection studies showed the functionality of the ERE. Enzyme mobility shift experiments with radiolabelled, cold and mutated probes indicate ERE-nuclear factor binding. This study is the first to report transcriptional regulation of arylphorins by 20E in lepdopteran insect species.
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Affiliation(s)
- V VenkatRao
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - R K Chaitanya
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - A Dutta-Gupta
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
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Hickman AB, Ewis HE, Li X, Knapp JA, Laver T, Doss AL, Tolun G, Steven AC, Grishaev A, Bax A, Atkinson PW, Craig NL, Dyda F. Structural basis of hAT transposon end recognition by Hermes, an octameric DNA transposase from Musca domestica. Cell 2014; 158:353-367. [PMID: 25036632 DOI: 10.1016/j.cell.2014.05.037] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/10/2014] [Accepted: 05/12/2014] [Indexed: 11/25/2022]
Abstract
Hermes is a member of the hAT transposon superfamily that has active representatives, including McClintock's archetypal Ac mobile genetic element, in many eukaryotic species. The crystal structure of the Hermes transposase-DNA complex reveals that Hermes forms an octameric ring organized as a tetramer of dimers. Although isolated dimers are active in vitro for all the chemical steps of transposition, only octamers are active in vivo. The octamer can provide not only multiple specific DNA-binding domains to recognize repeated subterminal sequences within the transposon ends, which are important for activity, but also multiple nonspecific DNA binding surfaces for target capture. The unusual assembly explains the basis of bipartite DNA recognition at hAT transposon ends, provides a rationale for transposon end asymmetry, and suggests how the avidity provided by multiple sites of interaction could allow a transposase to locate its transposon ends amidst a sea of chromosomal DNA.
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Affiliation(s)
- Alison B Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hosam E Ewis
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xianghong Li
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Joshua A Knapp
- Graduate Program in Biochemistry and Molecular Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Thomas Laver
- Graduate Program in Genetics, Genomics, and Bioinformatics, University of California Riverside, Riverside, CA 92521, USA
| | - Anna-Louise Doss
- Graduate Program in Cell, Molecular, and Developmental Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Gökhan Tolun
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alasdair C Steven
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alexander Grishaev
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter W Atkinson
- Graduate Program in Biochemistry and Molecular Biology, University of California Riverside, Riverside, CA 92521, USA; Graduate Program in Genetics, Genomics, and Bioinformatics, University of California Riverside, Riverside, CA 92521, USA; Graduate Program in Cell, Molecular, and Developmental Biology, University of California Riverside, Riverside, CA 92521, USA; Department of Entomology and Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Nancy L Craig
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Yang C, Lin Y, Liu H, Shen G, Luo J, Zhang H, Peng Z, Chen E, Xing R, Han C, Xia Q. The Broad Complex isoform 2 (BrC-Z2) transcriptional factor plays a critical role in vitellogenin transcription in the silkworm Bombyx mori. Biochim Biophys Acta Gen Subj 2014; 1840:2674-84. [DOI: 10.1016/j.bbagen.2014.05.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/22/2014] [Accepted: 05/16/2014] [Indexed: 11/16/2022]
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Juvenile hormone and its receptor, methoprene-tolerant, control the dynamics of mosquito gene expression. Proc Natl Acad Sci U S A 2013; 110:E2173-81. [PMID: 23633570 DOI: 10.1073/pnas.1305293110] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Juvenile hormone III (JH) plays a key role in regulating the reproduction of female mosquitoes. Microarray time-course analysis revealed dynamic changes in gene expression during posteclosion (PE) development in the fat body of female Aedes aegypti. Hierarchical clustering identified three major gene clusters: 1,843 early-PE (EPE) genes maximally expressed at 6 h PE, 457 mid-PE (MPE) genes at 24 h PE, and 1,815 late-PE (LPE) genes at 66 h PE. The RNAi microarray screen for the JH receptor Methoprene-tolerant (Met) showed that 27% of EPE and 40% of MPE genes were up-regulated whereas 36% of LPE genes were down-regulated in the absence of this receptor. Met repression of EPE and MPE and activation of LPE genes were validated by an in vitro fat-body culture experiment using Met RNAi. Sequence motif analysis revealed the consensus for a 9-mer Met-binding motif, CACG(C)/TG(A)/G(T)/AG. Met-binding motif variants were overrepresented within the first 300 bases of the promoters of Met RNAi-down-regulated (LPE) genes but not in Met RNAi-up-regulated (EPE) genes. EMSAs using a combination of mutational and anti-Met antibody supershift analyses confirmed the binding properties of the Met consensus motif variants. There was a striking temporal separation of expression profiles among major functional gene groups, with carbohydrate, lipid, and xenobiotics metabolism belonging to the EPE and MPE clusters and transcription and translation to the LPE cluster. This study represents a significant advancement in the understanding of the regulation of gene expression by JH and its receptor Met during female mosquito reproduction.
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Heterodimer of two bHLH-PAS proteins mediates juvenile hormone-induced gene expression. Proc Natl Acad Sci U S A 2010; 108:638-43. [PMID: 21187375 DOI: 10.1073/pnas.1013914108] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Juvenile hormone (JH) plays crucial roles in many aspects of insect life. The Methoprene-tolerant (Met) gene product, a member of the bHLH-PAS family of transcriptional regulators, has been demonstrated to be a key component of the JH signaling pathway. However, the molecular function of Met in JH-induced signal transduction and gene regulation remains to be fully elucidated. Here we show that a transcriptional coactivator of the ecdysteroid receptor complex, FISC, acts as a functional partner of Met in mediating JH-induced gene expression. Met and FISC appear to use their PAS domains to form a dimer only in the presence of JH or JH analogs. In newly emerged adult female mosquitoes, expression of some JH responsive genes is considerably dampened when Met or FISC is depleted by RNAi. Met and FISC are found to be associated with the promoter of the early trypsin gene (AaET) when transcription of this gene is activated by JH. A juvenile hormone response element (JHRE) has been identified in the AaET upstream regulatory region and is bound in vitro by the Met-FISC complex present in the nuclear protein extracts of previtellogenic adult female mosquitoes. In addition, the Drosophila homologs of Met and FISC can also use this mosquito JHRE to activate gene transcription in response to JH in a cell transfection assay. Together, the evidence indicates that Met and FISC form a functional complex on the JHRE in the presence of JH and directly activate transcription of JH target genes.
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Mané-Padrós D, Cruz J, Vilaplana L, Nieva C, Ureña E, Bellés X, Martín D. The hormonal pathway controlling cell death during metamorphosis in a hemimetabolous insect. Dev Biol 2010; 346:150-60. [DOI: 10.1016/j.ydbio.2010.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/28/2010] [Accepted: 07/09/2010] [Indexed: 10/19/2022]
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Fallon AM, Gerenday A. Ecdysone and the cell cycle: investigations in a mosquito cell line. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:1396-401. [PMID: 20303973 PMCID: PMC2918671 DOI: 10.1016/j.jinsphys.2010.03.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Revised: 03/06/2010] [Accepted: 03/09/2010] [Indexed: 05/25/2023]
Abstract
Cell lines provide a tool for investigating basic biological processes that underlie the complex interactions among the tissues and organs of an intact organism. We compare the evolution of insect and mammalian populations as they progress from diploid cell strains to continuous cell lines, and review the history of the well-characterized Aedes albopictus mosquito cell line, C7-10. Like Kc and S3 cells from Drosophila melanogaster, C7-10 cells are sensitive to the insect steroid hormone, 20-hydroxyecdysone (20E), and express 20E-inducible proteins as well as the EcR and USP components of the ecdysteroid receptor. The decrease in growth associated with 20E treatment results in an accumulation of cells in the G1 phase of the cycle, and a concomitant decrease in levels of cyclin A. In contrast, 20E induces a G2 arrest in a well-studied imaginal disc cell line from the moth, Plodia interpunctella. We hypothesize that 20E-mediated events associated with molting and metamorphosis include effects on regulatory proteins that modulate the mitotic cell cycle and that differences between the 20E response in diverse insect cell lines reflect an interplay between classical receptor-mediated effects on gene expression and non-classical effects on signaling pathways similar to those recently described for the vertebrate steroid hormone, estrogen.
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Affiliation(s)
- Ann M Fallon
- Department of Entomology, University of Minnesota, 1980 Folwell Ave., St. Paul, MN 55108, United States.
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9
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Cruz J, Nieva C, Mané-Padrós D, Martín D, Bellés X. Nuclear receptor BgFTZ-F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insectBlattella germanica. Dev Dyn 2008; 237:3179-91. [DOI: 10.1002/dvdy.21728] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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10
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Sok AJ, Andruszewska G, Niewiadomska-Cimicka A, Grad I, Rymarczyk G, Pajdzik D, Orłowski M, Schmidt MT, Grajek W, Ożyhar A, Kochman M. Regulatory elements in the juvenile hormone binding protein gene from Galleria mellonella — Topography of binding sites for Usp and EcRDBD. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1779:390-401. [DOI: 10.1016/j.bbagrm.2008.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 04/12/2008] [Accepted: 04/29/2008] [Indexed: 11/16/2022]
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11
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The non-dosage compensated Lsp1alpha gene of Drosophila melanogaster escapes acetylation by MOF in larval fat body nuclei, but is flanked by two dosage compensated genes. BMC Mol Biol 2007; 8:35. [PMID: 17511883 PMCID: PMC1890558 DOI: 10.1186/1471-2199-8-35] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Accepted: 05/19/2007] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND In Drosophila melanogaster dosage compensation of most X-linked genes is mediated by the male-specific lethal (MSL) complex, which includes MOF. MOF acetylates histone H4 at lysine 16 (H4K16ac). The X-linked Larval serum protein one alpha (Lsp1alpha) gene has long been known to be not dosage compensated. Here we have examined possible explanations for why the Lsp1alpha gene is not dosage compensated. RESULTS Quantitative RNase protection analysis showed that the genes flanking Lsp1alpha are expressed equally in males and females and confirmed that Lsp1alpha is not dosage compensated. Unlike control X-linked genes, Lsp1alpha was not enriched for H4K16ac in the third instar larval fat body, the tissue in which the gene is actively expressed. X-linked Lsp1alpha promoter-lacZ reporter transgenes are enriched for H4K16ac in third instar larval fat body. An X-linked reporter gene bracketed by Lsp1alpha flanking regions was dosage compensated. One of the genes flanking Lsp1alpha is expressed in the same tissue. This gene shows a modest enrichment for H4K16ac but only at the part of the gene most distant from Lsp1alpha. Phylogenetic analyses of the sequences of the genomes of 12 Drosophila species shows that Lsp1alpha is only present within the melanogaster subgroup of species. CONCLUSION Lsp1alpha is not modified by the MSL complex but is in a region of the X chromosome that is regulated by the MSL complex. The high activity or tissue-specificity of the Lsp1alpha promoter does not prevent regulation by the MSL complex. The regions flanking Lsp1alpha do not appear to block access by the MSL complex. Lsp1alpha appears to have recently evolved within the melanogaster subgroup of Drosophila species. The most likely explanation for why Lsp1alpha is not dosage compensated is that the gene has not evolved a mechanism to independently recruit the MSL complex, possibly because of its recent evolutionary origin, and because there appears to be a low level of bound MSL complex in a nearby gene that is active in the same tissue.
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Park JH, Attardo GM, Hansen IA, Raikhel AS. GATA factor translation is the final downstream step in the amino acid/target-of-rapamycin-mediated vitellogenin gene expression in the anautogenous mosquito Aedes aegypti. J Biol Chem 2006; 281:11167-76. [PMID: 16490782 DOI: 10.1074/jbc.m601517200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ingestion of blood is required for vector mosquitoes to initiate reproductive cycles determining their role as vectors of devastating human diseases. Nutritional signaling plays a pivotal role in regulating mosquito reproduction. Transcription of yolk protein precursor genes is repressed until mosquitoes take blood. Previously, we have shown that to signal the presence of blood in the gut, mosquitoes utilize the target-of-rapamycin (TOR) pathway. The TOR signaling pathway transduces the amino acid signal activating the major yolk protein precursor gene, vitellogenin (Vg). Here we report the identification of a GATA factor (AaGATAa) that is synthesized after a blood meal and acts as a transcriptional activator of Vg. We showed that AaGATAa bound specifically to GATA-binding sites present in the proximal promoter region of the Vg gene and positively regulated Vg expression in transfection assays. RNA interference-mediated knock down of AaGATAa transcript resulted in a significant inhibition of Vg expression in both fat-body tissue culture and blood-fed mosquitoes. AaGATAa mRNA accumulated in the fat body prior to blood feeding. However, translation of GATA was activated by blood feeding because the GATA protein increased dramatically in the fat body of blood-fed mosquitoes. This increase was also reproduced in the fat-body culture stimulated with amino acids. GATA translation was inhibited by rapamycin and cycloheximide as well as by RNA interference-mediated knock down of S6 kinase. These experiments have revealed that the TOR signaling pathway induced by nutritional signaling regulates the translation of a GATA factor, which is the specific transcriptional activator of the Vg gene.
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Affiliation(s)
- Jong-Hwa Park
- Center for Disease-Vector Research, Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
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Sun G, Zhu J, Chen L, Raikhel AS. Synergistic action of E74B and ecdysteroid receptor in activating a 20-hydroxyecdysone effector gene. Proc Natl Acad Sci U S A 2005; 102:15506-11. [PMID: 16230625 PMCID: PMC1266084 DOI: 10.1073/pnas.0503501102] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A number of insect effector genes activated by the steroid hormone 20-hydroxyecdysone (20E) are dually controlled by the ecdysteroid receptor (EcR/USP) and products of ecdysteroid early responsive genes (E74, E75, and Broad). However, the molecular mechanism of this dual action is poorly understood. Here we examined transcriptional activation of the vitellogenin (Vg) gene in the yellow fever mosquito, Aedes aegypti, by EcR/USP and E74 in response to an elevation of 20E titers. There are two isoforms of the Aedes E74 gene, AaE74A and AaE74B, which have a common C-terminal Ets DNA-binding domain and isoform-specific N termini in the female mosquito. Inhibiting expression of AaE74B but not AaE74A by RNA interference led to substantial reduction in the Vg gene expression. AaE74B and the ecdysteroid receptor synergistically enhanced 20E-induced transcription of the Vg promoter. This action required the E74-binding sites and the ecdysone response elements in the Vg 5' regulatory region. Two-hybrid assays and coimmunoprecipitation analyses demonstrated direct interaction between AaE74B and AaEcR/AaUSP. Moreover, disruption of this interaction by a dominant negative E74 mutant abolished the enhanced activation of Vg. Therefore, the cooperative interaction between AaE74B and the ecdysteroid receptor is required for high-level expression of the Vg gene in vivo. The synergistic activation is accomplished through their 20E-dependent protein-protein interaction on the gene promoter. This study reveals how the 20E direct-indirect regulation of an effector gene is achieved at the molecular level.
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Affiliation(s)
- GuoQiang Sun
- Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, CA 92521, USA
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Sun G, Zhu J, Raikhel AS. The early gene E74B isoform is a transcriptional activator of the ecdysteroid regulatory hierarchy in mosquito vitellogenesis. Mol Cell Endocrinol 2004; 218:95-105. [PMID: 15130514 DOI: 10.1016/j.mce.2003.12.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Accepted: 12/17/2003] [Indexed: 10/26/2022]
Abstract
In the mosquito Aedes aegypti, blood feeding activates vitellogenesis that involves yolk protein precursor (YPP) genes in an insect metabolic tissue, the fat body. Vitellogenesis is regulated by the 20-hydroxyecdysone (20E) regulatory hierarchy, in which the Ets-domain protein E74 is a key transcriptional regulator. The mosquito AaE74 gene encodes two isoforms-AaE74A and AaE74B. Both AaE74 isoforms are 20E-inducible early gene products. AaE74B reaches its maximal expression at 10(-7)M of 20E, while AaE74A requires 10(-6)M of 20E, a concentration at which the YPP genes reach their maximal induction level. In transfection assay, AaE74B is capable of activating a reporter construct containing E74-response elements, while expression of AaE74A has no effect on the basal levels of the reporter. The AaE74B binding activity is present in the fat body nuclei only during active vitellogenesis. Taken together, our findings demonstrate that AaE74B isoform plays the role of a transcriptional activator during vitellogenesis.
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Affiliation(s)
- GuoQiang Sun
- Department of Entomology, University of California, Riverside, CA 92521, USA
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Dittmer NT, Sun G, Wang SF, Raikhel AS. CREB isoform represses yolk protein gene expression in the mosquito fat body. Mol Cell Endocrinol 2003; 210:39-49. [PMID: 14615059 DOI: 10.1016/j.mce.2003.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In mosquitoes, the steroid 20-hydroxyecdysone (20E) is the main regulator of yolk protein precursor (YPP) gene expression. However, peptide hormones have also been implicated. To investigate involvement of the cAMP-mediated signal-transduction cascade in regulation of mosquito vitellogenic events, we cloned an Aedes aegypti cAMP response element binding protein (AaCREB). The AaCREB contained the domains characteristic to members of the cAMP response element binding protein (CREB) family of transcription factors: a kinase inducible domain region and a bZIP domain responsible for DNA binding and protein dimerization. In the mosquito fat body (site of YPP gene expression), the AaCREB gene was constitutively expressed and produced a transcript of 3.5-4 kb. In vitro fat body organ culture experiments demonstrated that elicitors of the cAMP signal-transduction pathway attenuated 20E-stimulated YPP gene expression. Cell transfection analysis indicated that AaCREB served as a potent repressor of transcription (designated AaCREBr). The role of AaCREBr as a transcriptional repressor supported the electrophoretic mobility shift assay (EMSA) with nuclear extracts from vitellogenic fat bodies. This analysis detected CREB-specific band-shift complexes in nuclear extracts at 24 and 36 h post-blood meal (PBM), when YPP gene expression reaches its peak then terminates. Examination of the regulatory regions of two major YPP genes, vitellogenin (Vg) and vitellogenic carboxypeptidase (VCP), revealed the presence of putative CREB response elements (CREs). These elements competed with the CRE consensus sequence for binding of in vitro-expressed AaCREBr. We propose that AaCREBr functions as a repressor of YPP gene expression at the time of vitellogenesis termination in the fat body.
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Affiliation(s)
- Neal T Dittmer
- Program in Genetics, Michigan State University, East Lansing, MI 48824, USA
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Zhu J, Chen L, Raikhel AS. Posttranscriptional control of the competence factor betaFTZ-F1 by juvenile hormone in the mosquito Aedes aegypti. Proc Natl Acad Sci U S A 2003; 100:13338-43. [PMID: 14593204 PMCID: PMC263810 DOI: 10.1073/pnas.2234416100] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In anautogenous mosquitoes, vitellogenesis, which includes production of yolk protein precursors, requires blood feeding. Consequently, mosquitoes transmit many diseases. Understanding the molecular mechanisms of vitellogenesis regulation will contribute significantly to vector control strategies. Newly emerged Aedes aegypti females require 3 days before becoming competent to activate vitellogenesis in response to a blood-meal-initiated, elevated titer of 20-hydroxyecdysone (20E). An orphan nuclear receptor gene betaFTZ-F1 is transcribed in the fat body of newly emerged mosquito females; however, the betaFTZ-F1 protein is only found 3 days later. Dramatically increased titer of the juvenile hormone III (JH III) is essential for the acquisition of 20E competence. In vitro fat body culture experiments have shown that betaFTZ-F1 protein appears after exposure to JH III. Injection of double-stranded RNA complementary to betaFTZ-F1 into newly emerged females attenuated expression of the early genes EcR-B, E74B, and E75A and the target YPP gene Vg, in response to a blood meal. Thus, betaFTZ-F1 is indeed the factor defining the acquisition of competence to 20E in the mosquito fat body. Moreover, this is achieved through JH III-mediated posttranscriptional control of betaFTZ-F1.
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Affiliation(s)
- Jinsong Zhu
- Department of Entomology, University of California, Riverside, CA 92521, USA
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Abstract
We investigated the role of 20-hydroxyecdysone (20E) on the ovarian maturation and protein levels and pattern in adult females of the spider Tegenaria atrica. In unmated females, the ovaries did not initiate vitellogenesis and levels of proteins in the hemolymph and ovaries were low. Unmated females treated with 20E showed an increase in the total amount of proteins in their hemolymph and ovaries, comparable with that in untreated mated females. Vitellogenesis was observable histologically in 20E treated unmated females as in untreated mated ones. The electrophoretic analysis of total proteins revealed a 47 kDa band expressed in the vitellogenic ovaries and hemolymph of 20E treated unmated females and untreated mated ones as in newly laid eggs. We hypothesize that this 47 kDa protein could belong to the vitellogenin-vitellin complex. We describe in this paper, for the first time in a spider, the partial characterization of putative yolk protein.
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Affiliation(s)
- Grégory Pourié
- Faculté des sciences, Laboratoire de Biologie et Physiologie du Comportement, B.P. 239, 54506 Vandoeuvre-Les-Nancy Cedex, France
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18
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Zhu J, Miura K, Chen L, Raikhel AS. Cyclicity of mosquito vitellogenic ecdysteroid-mediated signaling is modulated by alternative dimerization of the RXR homologue Ultraspiracle. Proc Natl Acad Sci U S A 2003; 100:544-9. [PMID: 12522263 PMCID: PMC141032 DOI: 10.1073/pnas.0235695100] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In anautogenous mosquitoes, egg maturation requires a blood meal. As a consequence, mosquitoes are vectors of numerous devastating human diseases. Blood feeding triggers a 20-hydroxyecdysone (20E) hormonal cascade, which activates yolk protein precursor (YPP) genes in the female fat body, an insect metabolic tissue. An important adaptation for anautogeny is the previtellogenic arrest preventing activation of YPP genes. Equally essential is termination of their expression, so that another arrest is achieved after a batch of eggs is laid. Here, we report that mosquito Seven-up (AaSvp), a chicken ovalbumin upstream promoter-transcription factor homologue, is involved in regulating the cyclicity of vitellogenic ecdysteroid-mediated signaling through heterodimerization with a retinoid X receptor homologue Ultraspiracle (USP), the obligatory functional ecdysteroid receptor (EcR) partner. AaSvp inhibits 20E-dependent activation of the vitellogenin (Vg) gene in transfection assays. Two-hybrid and GST pull-down analyses demonstrate that in vitro AaSvp interacts with both AaUSP and AaEcR. However, the coimmunoprecipitation using fat body nuclear extracts reveals that at 33-36 h postblood meal, when the 20E titer sharply declines and YPP gene expression ceases, AaSvp replaces AaEcR in USP heterodimers. The chromatin immunoprecipitation assay indicates that protein-protein interaction rather than binding competition for the Vg ecdysteroid response element accounts for the inhibition of Vg expression by AaSvp.
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Affiliation(s)
- Jinsong Zhu
- Department of Entomology, University of California, Riverside, CA 92521, USA
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19
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Durica DS, Wu X, Anilkumar G, Hopkins PM, Chung ACK. Characterization of crab EcR and RXR homologs and expression during limb regeneration and oocyte maturation. Mol Cell Endocrinol 2002; 189:59-76. [PMID: 12039065 DOI: 10.1016/s0303-7207(01)00740-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report here complete coding sequences for the Uca pugilator homologs of the ecdysteroid (UpEcR) and retinoid-X receptors (UpRXR). Library screenings recovered cDNA clones containing a unique amino terminal open-reading frame (A/B domain) for each gene, most similar to insect B1 EcR and USP1/RXR isoforms. Splicing variants in the UpRXR ligand-binding domain were also identified, in a region critical for folding of Drosophila and lepidopteran USP. UpEcR and UpRXR proteins were able to associate, and both are required for binding to an ecdysteroid HRE; these interactions were not hormone-dependent. Ribonuclease protection assays (RPA) were conducted using A/B domain and 'common' (C or E) domain probes on RNA isolated from various stages of regenerating limb buds and ovaries. For several of the limb bud and ovarian stages examined, the relative level of A/B domain sequence protected was significantly less than common domain suggesting alternative amino terminal isoforms other than those isolated through cloning. This is the first report of UpEcR and UpRXR transcription during ovarian maturation, implicating the ovary as a potential target for hormonal control in Crustacea.
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Affiliation(s)
- David S Durica
- Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA.
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20
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Jayachandran G, Fallon AM. Antisense expression of the 20-hydroxyecdysone receptor (EcR) in transfected mosquito cells uncovers a new EcR isoform that varies at the C-terminal end. In Vitro Cell Dev Biol Anim 2001; 37:522-9. [PMID: 11669286 DOI: 10.1290/1071-2690(2001)037<0522:aeothr>2.0.co;2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The insect steroid hormone 20-hydroxyecdysone initiates a cascade of regulatory events in a temporal and tissue-specific manner by first binding to a complex of an ecdysone receptor (EcR) protein and a ultraspiracle protein. Using an antisense (As) ribonucleic acid approach, we show that disruption of EcR expression in transfected C7-10 cells from the mosquito Aedes albopictus affects survival and growth. From stably transfected cells, we recovered a new isoform of A. albopictus AalEcRa, which is named AalEcRb. The deduced amino acid sequence of AalEcRb was almost identical to that of AalEcRa, with the exception of a seven amino acid sequence near the C-terminus. Using polymerase chain reaction followed by restriction enzyme analysis, we found that AalEcRa is the predominant species expressed by wild-type C7-10 cells, while cells transfected with As-EcR expressed both isoforms at approximately equal levels.
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Affiliation(s)
- G Jayachandran
- Department of Entomology, University of Minnesota, St Paul, Minnesota 55108, USA.
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21
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Kokoza VA, Martin D, Mienaltowski MJ, Ahmed A, Morton CM, Raikhel AS. Transcriptional regulation of the mosquito vitellogenin gene via a blood meal-triggered cascade. Gene 2001; 274:47-65. [PMID: 11674997 DOI: 10.1016/s0378-1119(01)00602-3] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In anautogenous mosquitoes, a blood meal is required for activation of genes encoding yolk protein precursors (YPP). Vitellogenin (Vg), the major YPP gene, is transcribed at a very high level following blood meal activation. It is expressed exclusively in the female fat body, the tissue producing most of mosquito hemolymph and immune proteins. In this paper, we analyzed the upstream region of the Aedes aegypti Vg gene in order to identify regulatory elements responsible for its unique expression pattern. To achieve this goal, we analyzed the gene using transgenic Drosophila and Aedes as well as DNA-binding assays. These analyses revealed three regulatory regions in the 2.1 kb upstream portion of the Vg gene. The proximal region containing binding sites to EcR/USP, GATA, C/EBP and HNF3/fkh is required for the correct tissue- and stage-specific expression at a low level. The median region carrying sites for early ecdysone response factors E74 and E75 is responsible for hormonal enhancement of Vg expression. Finally, the distal GATA-rich region is necessary for extremely high expression levels characteristic of the Vg gene. The present work elucidates the molecular basis of blood meal-dependent expression of this mosquito gene, laying the foundation for mosquito-specific expression cassettes with predictable stage and tissue specificity.
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Affiliation(s)
- V A Kokoza
- Department of Entomology and Program in Genetics, Michigan State University, East Lansing, MI 48824, USA
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22
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Abstract
The term "endocrine disrupting chemicals" is commonly used to describe environmental agents that alter the endocrine system. Laboratories working in this emerging field-environmental endocrine research-have looked at chemicals that mimic or block endogenous vertebrate steroid hormones by interacting with the hormone's receptor. Environmental chemicals known to do this do so most often with receptors derived from the steroid/thyroid/retinoid gene family. They include ubiquitous and persistent organochlorines, as well as plasticizers, pharmaceuticals, and natural hormones. These chemicals function as estrogens, antiestrogens, and antiandrogens but have few, if any, structural similarities. Therefore, receptor-based or functional assays have the best chance of detecting putative biological activity of environmental chemicals. Three nuclear estrogen receptor forms-alpha, beta, and gamma-as well as multiple membrane forms and a possible mitochondrial form have been reported, suggesting a previously unknown diversity of signaling pathways available to estrogenic chemicals. Examples of environmental or ambient estrogenization occur in laboratory experiments, zoo animals, domestic animals, wildlife, and humans. Environmentally estrogenized phenotypes may differ depending upon the time of exposure-i.e., whether the exposure occurred at a developmental (organizational and irreversible) or postdevelopmental (activational and reversible) stage. The term "estrogen" must be defined in each case, since steroidal estrogens differ among themselves and from synthetic or plant-derived chemicals. An "estrogen-like function" seems to be an evolutionarily ancient signal that has been retained in a number of chemicals, some of which are vertebrate hormones. Signaling, required for symbiosis between plants and bacteria, may be viewed, therefore, as an early example of hormone cross-talk. Developmental feminization at the structural or functional level is an emerging theme in species exposed, during embryonic or fetal life, to estrogenic compounds. Human experience as well as studies in experimental animals with the potent estrogen diethylstilbestrol provide informative models. Advances in the molecular genetics of sex differentiation in vertebrates facilitate mechanistic understanding. Experiments addressing the concept of gene imprinting or induction of epigenetic memory by estrogen or other hormones suggest a link to persistent, heritable phenotypic changes seen after developmental estrogenization, independent of mutagenesis. Environmental endocrine science provides a new context in which to examine the informational content of ecosystem-wide communication networks. As common features come to light, this research may allow us to predict environmentally induced alterations in internal signaling systems of vertebrates and some invertebrates and eventually to explicate environmental contributions to human reproductive and developmental health.
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Affiliation(s)
- J A McLachlan
- Department of Pharmacology, Tulane University Health Sciences Center, Environmental Endocrinology Laboratory, Center for Bioenvironmental Research, Tulane and Xavier Universities, New Orleans, Louisiana 70112-2699, USA.
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23
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Martín D, Wang SF, Raikhel AS. The vitellogenin gene of the mosquito Aedes aegypti is a direct target of ecdysteroid receptor. Mol Cell Endocrinol 2001; 173:75-86. [PMID: 11223179 DOI: 10.1016/s0303-7207(00)00413-5] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the female mosquito Aedes aegypti, vitellogenin (Vg), the major YPP, is activated by 20-hydroxyecdysone (20E) at the transcriptional level. We used cell transfection assays in the Drosophila S2 cells to investigate whether 20E acts directly on the Vg gene via its functional receptor, the heterodimer composed of the ecdysteroid receptor (EcR) and the ultraspiracle (USP) proteins. We demonstrated that the Vg 5'-regulatory region contains a functional ecdysteroid-responsive element (VgEcRE1) that is necessary to confer responsiveness to 20E. VgEcRE binds directly to EcR-USP produced in vitro and extracted from the vitellogenic fat body nuclei. The binding intensity of the EcR-USP-EcRE1 complex from nuclear extracts corresponds to the levels of ecdysteroids and of the Vg transcript during the vitellogenic cycle. Given the modest level of 20E-dependent activation, it is likely that the EcR-USP receptor acts synergistically with other transcription factors to bring about the high level of Vg gene expression.
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Affiliation(s)
- D Martín
- Department of Entomology and Programs in Genetics and Cell and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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24
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Riddiford LM, Cherbas P, Truman JW. Ecdysone receptors and their biological actions. VITAMINS AND HORMONES 2001; 60:1-73. [PMID: 11037621 DOI: 10.1016/s0083-6729(00)60016-x] [Citation(s) in RCA: 370] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- L M Riddiford
- Department of Zoology, University of Washington, Seattle 98195-1800, USA
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25
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Martín D, Piulachs MD, Raikhel AS. A novel GATA factor transcriptionally represses yolk protein precursor genes in the mosquito Aedes aegypti via interaction with the CtBP corepressor. Mol Cell Biol 2001; 21:164-74. [PMID: 11113191 PMCID: PMC88790 DOI: 10.1128/mcb.21.1.164-174.2001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of many devastating human diseases. An important adaptation for anautogenicity is the previtellogenic arrest (the state of arrest) preventing the activation of the yolk protein precursor (YPP) genes Vg and VCP prior to blood feeding. A novel GATA factor (AaGATAr) that recognizes GATA binding motifs (WGATAR) in the upstream region of the YPP genes serves as a transcriptional repressor at the state of arrest. Importantly, AaGATAr can override the 20-hydroxyecdysone transactivation of YPP genes, and its transcriptional repression involves the recruitment of CtBP, one of the universal corepressors. AaGATAr transcript is present only in the adult female fat body. Furthermore, in nuclear extracts of previtellogenic fat bodies with transcriptionally repressed YPP genes, there is a GATA binding protein forming a band with mobility similar to that of AaGATAr. The specific repression of YPP genes by AaGATAr in the fat body of the female mosquito during the state of arrest represents an important molecular adaptation for anautogenicity.
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Affiliation(s)
- D Martín
- Department of Entomology and Program in Genetics, Michigan State University, East Lansing, Michigan 48824, USA
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26
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Li C, Kapitskaya MZ, Zhu J, Miura K, Segraves W, Raikhel AS. Conserved molecular mechanism for the stage specificity of the mosquito vitellogenic response to ecdysone. Dev Biol 2000; 224:96-110. [PMID: 10898964 DOI: 10.1006/dbio.2000.9792] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the mosquito Aedes aegypti, the adult female becomes competent for a vitellogenic response to ecdysone after previtellogenic development. Here, we show that betaFTZ-F1, the nuclear receptor implicated as a competence factor for stage-specific responses to ecdysone during Drosophila metamorphosis, serves a similar function during mosquito vitellogenesis. AaFTZ-F1 is expressed highly in the mosquito fat body during pre- and postvitellogenic periods when ecdysteroid titers are low. The mosquito AaFTZ-F1 transcript nearly disappears in mid-vitellogenesis when ecdysteroid titers are high. An expression peak of HR3, a nuclear receptor implicated in the activation of betaFTZ-F1 in Drosophila, precedes each rise in mosquito FTZ-F1 expression. In in vitro fat body culture, AaFTZ-F1 expression is inhibited by 20-hydroxyecdysone (20E) and superactivated by its withdrawal. Following in vitro AaFTZ-F1 superactivation, a secondary 20E challenge results in superinduction of the early AaE75 gene and the late target VCP gene. Electrophoretic mobility-shift assays show that the onset of ecdysone-response competence in the mosquito fat body is correlated with the appearance of the functional AaFTZ-F1 protein at the end of the previtellogenic development. These findings suggest that a conserved molecular mechanism for controlling stage specificity is reiteratively used during metamorphic and reproductive responses to ecdysone.
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Affiliation(s)
- C Li
- Program in Genetics and Department of Entomology, Michigan State University, East Lansing, Michigan 48824, USA
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27
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Wang SF, Li C, Zhu J, Miura K, Miksicek RJ, Raikhel AS. Differential expression and regulation by 20-hydroxyecdysone of mosquito ultraspiracle isoforms. Dev Biol 2000; 218:99-113. [PMID: 10644414 DOI: 10.1006/dbio.1999.9575] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ultraspiracle (USP), the insect homologue of the vertebrate retinoid X receptor, is an obligatory dimerization partner for the ecdysteroid receptor (EcR). Two USP isoforms, USP-A and USP-B, with distinct N-termini, occur in the mosquito Aedes aegypti. In the fat body and ovary, USP-A mRNA is highly expressed during the pre- and late vitellogenic stages, corresponding to a period of low ecdysteroid titer, while USP-B mRNA exhibits its highest levels during the vitellogenic period, correlating with a high ecdysteroid titer. Remarkably, 20-hydroxyecdysone (20E) has opposite effects on USP isoform transcripts in in vitro fat body culture. This steroid hormone upregulates USP-B transcription and its presence is required to sustain a high level of USP-B expression. In contrast, 20E inhibits activation of USP-A transcription. Although EcR.USP-A recognizes the same ecdysteroid-responsive elements, EcR.USP-B binds them with an affinity twofold higher than that of EcR.USP-A. Likewise, EcR.USP-B transactivates a reporter gene in CV-1 cells twofold more strongly than EcR.USP-A. These results suggest that USP-B functions as a major heterodimerization partner for EcR during the vitellogenic response to 20E in the mosquito.
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Affiliation(s)
- S F Wang
- Department of Entomology, Michigan State University, East Lansing, Michigan, 48824, USA
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28
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Zhu J, Miura K, Chen L, Raikhel AS. AHR38, a homolog of NGFI-B, inhibits formation of the functional ecdysteroid receptor in the mosquito Aedes aegypti. EMBO J 2000; 19:253-62. [PMID: 10637229 PMCID: PMC305559 DOI: 10.1093/emboj/19.2.253] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of numerous devastating human diseases. After ingestion of blood, 20-hydroxyecdysone activates yolk protein precursor (YPP) genes in the metabolic tissue, the fat body. An important adaptation for anautogenicity is the previtellogenic developmental arrest (the state-of-arrest) preventing the activation of YPP genes in previtellogenic females prior to blood feeding. Here, we show that a retinoid X receptor homolog, Ultraspiracle (AaUSP), which is an obligatory partner in the functional ecdysteroid receptor, exists at the state-of-arrest as a heterodimer with the orphan nuclear receptor AHR38, a homolog of Drosophila DHR38 and nerve growth factor-induced protein B. Yeast two-hybrid and glutathione S-transferase pull-down assays demonstrate that AHR38 can interact strongly with AaUSP. AHR38 also disrupts binding of ecdysteroid receptor to ecdysone response elements. Cell co-transfection of AHR38 with AaEcR and AaUSP inhibits ecdysone-dependent activation of a reporter gene by the ecdysteroid receptor. Co-immunoprecipitation experiments indicate that AaUSP protein associates with AHR38 instead of AaEcR in fat body nuclei at the state-of-arrest.
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Affiliation(s)
- J Zhu
- Program in Genetics and Department of Entomology, Michigan State University, East Lansing, MI 488240-1115, USA
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29
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Ahmed A, Martín D, Manetti AG, Han SJ, Lee WJ, Mathiopoulos KD, Müller HM, Kafatos FC, Raikhel A, Brey PT. Genomic structure and ecdysone regulation of the prophenoloxidase 1 gene in the malaria vector Anopheles gambiae. Proc Natl Acad Sci U S A 1999; 96:14795-800. [PMID: 10611292 PMCID: PMC24727 DOI: 10.1073/pnas.96.26.14795] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Prophenoloxidase, a melanin-synthesizing enzyme, is considered to be an important arthropod immune protein. In mosquitoes, prophenoloxidase has been shown to be involved in refractory mechanisms against malaria parasites. In our study we used Anopheles gambiae, the most important human malaria vector, to characterize the first arthropod prophenoloxidase gene at the genomic level. The complete nucleotide sequence, including the immediate 5' flanking sequence (-855 bp) of the prophenoloxidase 1 gene, was determined. The gene spans 10 kb and is composed of five exons and four introns coding for a 2.5-kb mRNA. In the 5' flanking sequence, we found several putative regulatory motifs, two of which were identified as ecdysteroid regulatory elements. Electrophoretic mobility gel-shift assays and supershift assays demonstrated that the Aedes aegypti ecdysone receptor/Ultraspiracle nuclear receptor complex, and, seemingly, the endogenous Anopheles gambiae nuclear receptor complex, was able to bind one of the ecdysteroid response elements. Furthermore, 20-hydroxyecdysone stimulation was shown to up-regulate the transcription of the prophenoloxidase 1 gene in an A. gambiae cell line.
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Affiliation(s)
- A Ahmed
- Laboratoire de Biochimie et Biologie Moléculaire des Insectes, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
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