The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Lawrence I Gilbert - One of the best experts on this subject based on the ideXlab platform.
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neuroendocrine regulation of drosophila metamorphosis requires tgfβ activin signaling
Development, 2011Co-Authors: Ying Y Gibbens, Lawrence I Gilbert, James T. Warren, Michael B OconnorAbstract:In insects, initiation of metamorphosis requires a surge in the production of the steroid hormone 20-hydroxyecdysone from the Prothoracic Gland, the primary endocrine organ of juvenile larvae. Here, we show that blocking TGFβ/Activin signaling, specifically in the Drosophila Prothoracic Gland, results in developmental arrest prior to metamorphosis. The terminal, giant third instar larval phenotype results from a failure to induce the large rise in ecdysteroid titer that triggers metamorphosis. We further demonstrate that activin signaling regulates competence of the Prothoracic Gland to receive PTTH and insulin signals, and that these two pathways act at the mRNA and post-transcriptional levels, respectively, to control ecdysone biosynthetic enzyme expression. This dual regulatory circuitry may provide a cross-check mechanism to ensure that both developmental and nutritional inputs are synchronized before initiating the final genetic program leading to reproductive adult development. As steroid hormone production in C. elegans and mammals is also influenced by TGFβ/Activin signaling, this family of secreted factors may play a general role in regulating developmental transitions across phyla.
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Protein kinase C modulates ecdysteroidogenesis in the Prothoracic Gland of the tobacco hornworm, Manduca sexta.
Molecular and Cellular Endocrinology, 2006Co-Authors: Robert Rybczynski, Lawrence I GilbertAbstract:The Prothoracic Gland is the primary source of ecdysteroid hormones in the immature insect. Ecdysteroids coordinate gene expression necessary for growth, molting and metamorphosis. Prothoracicotropic hormone (PTTH), a brain neuropeptide, regulates ecdysteroid synthesis in the Prothoracic Gland. PTTH stimulates ecdysteroid synthesis through a signal transduction cascade that involves at least four protein kinases: protein kinase A (PKA), p70 S6 kinase, an unidentified tyrosine kinase, and the extracellular signal-regulated kinase (ERK). In this report, the participation of protein kinase C (PKC) in PTTH signalling is demonstrated and characterized. PTTH stimulates PKC activity through a PLC and Ca2+-dependent pathway that is not cAMP regulated. Inhibition of PKC inhibits PTTH-stimulated ecdysteroidogenesis as well as PTTH-stimulated phosphorylation of ERK and its upstream regulator, MAP/ERK kinase (MEK). These observations reveal that the acute regulation of Prothoracic Gland steroidogenesis is dependent on a web of interacting kinase pathways, which probably converge on factors that regulate translation.
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Control and biochemical nature of the ecdysteroidogenic pathway.
Annual review of entomology, 2002Co-Authors: Lawrence I Gilbert, Robert Rybczynski, James T. WarrenAbstract:Molting is elicited by a critical titer of ecdysteroids that includes the principal molting hormone, 20-hydroxyecdysone (20E), and ecdysone (E), which is the precursor of 20E but also has morphogenetic roles of its own. The Prothoracic Glands are the predominate source of ecdysteroids, and the rate of synthesis of these polyhydroxylated sterols is critical for molting and metamorphosis. This review concerns three aspects of ecdysteroidogenesis: (a) how the brain neuropeptide Prothoracicotropic hormone (PTTH) initiates a transductory cascade in cells of the Prothoracic Gland, which results in an increased rate of ecdysteroid biosynthesis (upregulation); (b) how the concentrations of 20E in the hemolymph feed back on the Prothoracic Gland to decrease rates of ecdysteroidogenesis (downregulation); and (c) how the Prothoracic Gland cells convert cholesterol to the precursor of E and then 20E, a series of reactions only now being understood because of the use of a combination of classical biochemistry and molecular genetics.
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activation of an extracellular signal regulated kinase erk by the insect Prothoracicotropic hormone
Molecular and Cellular Endocrinology, 2001Co-Authors: Robert Rybczynski, Stephanie C Bell, Lawrence I GilbertAbstract:Abstract Ecdysteroid hormones are crucial in controlling the growth, molting and metamorphosis of insects. The predominant source of ecdysteroids in pre-adult insects is the Prothoracic Gland, which is under the acute control of the neuropeptide hormone Prothoracicotropic hormone (PTTH). Previous studies using the tobacco hornworm, Manduca sexta, have shown that PTTH stimulates ecdysteroid synthesis via a series of events, including the activation of protein kinase A and the 70 kDa S6 kinase (p70S6k). In this study, PTTH was shown to stimulate also mitogen-activated protein kinase (MAPK) phosphorylation and activity in the Manduca Prothoracic Gland. The MAPK involved appears to be an extracellular signal-regulated kinase (ERK) homologue. The ERK phosphorylation inhibitors PD 98059 and UO 126 blocked basal and PTTH-stimulated ERK phosphorylation and ecdysteroid synthesis. PTTH-stimulated ERK activity may be important for both rapid regulation of ecdysteroid synthesis and for longer-term changes in the size and function of Prothoracic Gland cells.
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cdna cloning and expression of a hormone regulated heat shock protein hsc 70 from the Prothoracic Gland of manduca sexta
Insect Biochemistry and Molecular Biology, 2000Co-Authors: Robert Rybczynski, Lawrence I GilbertAbstract:The brain neuropeptide Prothoracicotropic hormone (PTTH) stimulates a rapid increase in ecdysteroid hormone synthesis that is accompanied by general and specific increases in protein synthesis, including that of a 70 kDa cognate heat shock protein (hsc 70). To further understand the possible roles of hsc 70, hsc 70 cDNA clones were isolated from a tobacco hornworm (Manduca sexta) Prothoracic Gland cDNA library. All sequenced clones were highly homologous to the Drosophila hsc 70-4 isoform. Manduca hsc 70 mRNA levels during the last larval instar exhibited a peak at the onset of wandering and a peak that coincided with the major pre-metamorphic peak of ecdysteroid synthesis. Manipulations of the Glands' hormonal milieu showed that hsc 70 mRNA levels respond to 20-hydroxyecdysone, dibutyryl cAMP, PTTH and the JH analogue hydroprene. The protein and mRNA data suggest that hsc 70 could be involved in a negative feedback loop regulating assembly of the ecdysone receptor complex.
Hiroshi Kataoka - One of the best experts on this subject based on the ideXlab platform.
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Deep sequencing of the Prothoracic Gland transcriptome reveals new players in insect ecdysteroidogenesis.
PLOS ONE, 2017Co-Authors: Takayoshi Nakaoka, Ikumi Koujima, Mika Takeshima, Xiangying Zhou, Mari H. Ogihara, Tetsuya Yamada, Yutaka Suzuki, Hiroshi KataokaAbstract:: Ecdysteroids are steroid hormones that induce molting and determine developmental timing in arthropods. In insect larva, the Prothoracic Gland (PG) is a major organ for ecdysone synthesis and release. Released ecdysone is converted into the active form, 20-hydroxyecdysone (20E) in the peripheral tissues. All processes from ecdysone synthesis and release from the PG to its conversion to 20E are called ecdysteroidogenesis and are under the regulation of numerous factors expressed in the PG and peripheral tissues. Classical genetic approaches and recent transcriptomic screening in the PG identified several genes responsible for ecdysone synthesis and release, whereas the regulatory mechanism remains largely unknown. We analyzed RNA-seq data of the silkworm Bombyx mori PG and employed the fruit fly Drosophila melanogaster GAL4/UAS binary RNAi system to comprehensively screen for genes involved in ecdysone synthesis and/or release. We found that the genes encoding δ-aminolevulinic acid synthase (CG3017/alas) and putative NAD kinase (CG33156) were highly expressed in the PG of both B. mori and D. melanogaster. Neither alas nor CG33156 RNAi-induced larvae could enter into the pupal stage, and they had a lower abundance of the active form ecdysteroids in their prolonged larval stage. These results demonstrated that alas and CG33156 are indispensable for ecdysteroidogenesis.
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Bombyx Prothoracicostatic peptides activate the sex peptide receptor to regulate ecdysteroid biosynthesis
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Naoki Yamanaka, Ivana Spalovska-valachova, Ladislav Roller, Akira Mizoguchi, Hiroshi Kataoka, Yoshiaki TanakaAbstract:Insect molting and metamorphosis are induced by steroid hormones named ecdysteroids, whose production is regulated by various neuropeptides. We cloned the gene and analyzed the expression of the Prothoracicostatic peptide, a unique neuropeptide shown to suppress the production of ecdysteroids in the Prothoracic Gland of the silkworm, Bombyx mori. We also characterized a Bombyx G protein-coupled receptor, which has previously been identified as an ortholog of the Drosophila sex peptide receptor, as a functional Prothoracicostatic peptide receptor. This receptor responded specifically to the Prothoracicostatic peptides when examined using a heterologous expression system. The receptor was highly expressed in the Prothoracic Gland on the day before each larval and pupal ecdysis, when Prothoracicostatic peptides are synthesized at a high level in the epiproctodeal Glands. These results suggest that the sex peptide receptor functions as a Prothoracicostatic peptide receptor in Bombyx and that the peripheral neurosecretory cells as well as the central neuroendocrine system play stage-specific roles in regulating ecdysteroidogenesis.
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A Basic-HLH Transcription Factor, HLH54F, Is Highly Expressed in the Prothoracic Gland in the Silkworm Bombyx mori and the Fruit Fly Drosophila melanogaster
Bioscience biotechnology and biochemistry, 2009Co-Authors: Toshiki Namiki, Ryusuke Niwa, Atsushi Higuchi, Takuji Yoshiyama, Kazuei Mita, Hiroshi KataokaAbstract:We describe our findings on HLH54F, a basic helix-loop-helix transcription factor gene that was highly expressed in the Prothoracic Gland, an organ producing the insect steroid ecdysone. HLH54F was uncovered by the use of an expressed sequence tag database of the silkworm Bombyx mori. It was also highly expressed in the Prothoracic Gland of the fruit fly Drosophila melanogaster.
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FXPRL-amide peptides induce ecdysteroidogenesis through a G-protein coupled receptor expressed in the Prothoracic Gland of Bombyx mori.
Molecular and cellular endocrinology, 2007Co-Authors: Ken Watanabe, J Joe Hull, Teruyuki Niimi, Kunio Imai, Shogo Matsumoto, Toshinobu Yaginuma, Hiroshi KataokaAbstract:The FXPRL-amide peptide family (pyrokinin/PBAN family) consists of insect peptides that function broadly in insect life processes and are characterized by a conserved C-terminal motif. In the silkworm, Bombyx mori, sex pheromone biosynthesis and induction of embryonic diapause are regulated by peptides from this family. To elucidate other functions of Bombyx FXPRL-amide peptides, we analyzed the tissue expression patterns of two known Bombyx G-protein coupled receptors for these peptides. We found that the Bombyx diapause hormone receptor (BmDHR), is expressed in the Prothoracic Gland (PG), the organ which synthesizes and releases the insect molting hormones, ecdysteroids. Furthermore, diapause hormone (DH), a member of the Bombyx FXPRL-amide peptides, increases both intracellular Ca(2+) and cAMP concentrations and induces ecdysteroidogenesis in late fifth instar PGs coincident with BmDHR expression in the PGs. DH also has the highest Prothoracicotropic activity among the FXPRL-amide peptides, which corresponds well to the ligand specificity of heterologously expressed BmDHR. These results demonstrate that FXPRL-amide peptides can function as Prothoracicotropic factors through the activation of BmDHR and may play an important role in controlling molting and metamorphosis.
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ghitm is an ortholog of the bombyx mori Prothoracic Gland derived receptor pgdr that is ubiquitously expressed in mammalian cells and requires an n terminal signal sequence for expression
Biochemical and Biophysical Research Communications, 2006Co-Authors: Tadashi Yoshida, Shinji Nagata, Hiroshi KataokaAbstract:In a previous paper, we reported the cloning of a cDNA encoding a putative receptor, Pgdr, from the Prothoracic Gland of the silkworm, Bombyx mori. Few studies concerning the orthologous cDNA of Pgdr in mammals, a growth hormone-inducible transmembrane protein (Ghitm) that encodes a putative receptor, have been performed. Analysis of the distribution of Ghitm expression revealed ubiquitous expression in mouse embryo and adult tissues, as well as mammalian cell lines. The pattern of Ghitm expression suggested that once Ghitm mRNA was expressed in the putative brain region of mouse embryo, Ghitm-expressing cells spread ubiquitously throughout all tissues during embryonic development. In addition, Western blot analyses demonstrated that cleavage of the N-terminal portion in GHITM appears to regulate the expression level, suggesting that cleavage is essential for the proper expression of GHITM.
Robert Rybczynski - One of the best experts on this subject based on the ideXlab platform.
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Protein kinase C modulates ecdysteroidogenesis in the Prothoracic Gland of the tobacco hornworm, Manduca sexta.
Molecular and Cellular Endocrinology, 2006Co-Authors: Robert Rybczynski, Lawrence I GilbertAbstract:The Prothoracic Gland is the primary source of ecdysteroid hormones in the immature insect. Ecdysteroids coordinate gene expression necessary for growth, molting and metamorphosis. Prothoracicotropic hormone (PTTH), a brain neuropeptide, regulates ecdysteroid synthesis in the Prothoracic Gland. PTTH stimulates ecdysteroid synthesis through a signal transduction cascade that involves at least four protein kinases: protein kinase A (PKA), p70 S6 kinase, an unidentified tyrosine kinase, and the extracellular signal-regulated kinase (ERK). In this report, the participation of protein kinase C (PKC) in PTTH signalling is demonstrated and characterized. PTTH stimulates PKC activity through a PLC and Ca2+-dependent pathway that is not cAMP regulated. Inhibition of PKC inhibits PTTH-stimulated ecdysteroidogenesis as well as PTTH-stimulated phosphorylation of ERK and its upstream regulator, MAP/ERK kinase (MEK). These observations reveal that the acute regulation of Prothoracic Gland steroidogenesis is dependent on a web of interacting kinase pathways, which probably converge on factors that regulate translation.
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Control and biochemical nature of the ecdysteroidogenic pathway.
Annual review of entomology, 2002Co-Authors: Lawrence I Gilbert, Robert Rybczynski, James T. WarrenAbstract:Molting is elicited by a critical titer of ecdysteroids that includes the principal molting hormone, 20-hydroxyecdysone (20E), and ecdysone (E), which is the precursor of 20E but also has morphogenetic roles of its own. The Prothoracic Glands are the predominate source of ecdysteroids, and the rate of synthesis of these polyhydroxylated sterols is critical for molting and metamorphosis. This review concerns three aspects of ecdysteroidogenesis: (a) how the brain neuropeptide Prothoracicotropic hormone (PTTH) initiates a transductory cascade in cells of the Prothoracic Gland, which results in an increased rate of ecdysteroid biosynthesis (upregulation); (b) how the concentrations of 20E in the hemolymph feed back on the Prothoracic Gland to decrease rates of ecdysteroidogenesis (downregulation); and (c) how the Prothoracic Gland cells convert cholesterol to the precursor of E and then 20E, a series of reactions only now being understood because of the use of a combination of classical biochemistry and molecular genetics.
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activation of an extracellular signal regulated kinase erk by the insect Prothoracicotropic hormone
Molecular and Cellular Endocrinology, 2001Co-Authors: Robert Rybczynski, Stephanie C Bell, Lawrence I GilbertAbstract:Abstract Ecdysteroid hormones are crucial in controlling the growth, molting and metamorphosis of insects. The predominant source of ecdysteroids in pre-adult insects is the Prothoracic Gland, which is under the acute control of the neuropeptide hormone Prothoracicotropic hormone (PTTH). Previous studies using the tobacco hornworm, Manduca sexta, have shown that PTTH stimulates ecdysteroid synthesis via a series of events, including the activation of protein kinase A and the 70 kDa S6 kinase (p70S6k). In this study, PTTH was shown to stimulate also mitogen-activated protein kinase (MAPK) phosphorylation and activity in the Manduca Prothoracic Gland. The MAPK involved appears to be an extracellular signal-regulated kinase (ERK) homologue. The ERK phosphorylation inhibitors PD 98059 and UO 126 blocked basal and PTTH-stimulated ERK phosphorylation and ecdysteroid synthesis. PTTH-stimulated ERK activity may be important for both rapid regulation of ecdysteroid synthesis and for longer-term changes in the size and function of Prothoracic Gland cells.
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cdna cloning and expression of a hormone regulated heat shock protein hsc 70 from the Prothoracic Gland of manduca sexta
Insect Biochemistry and Molecular Biology, 2000Co-Authors: Robert Rybczynski, Lawrence I GilbertAbstract:The brain neuropeptide Prothoracicotropic hormone (PTTH) stimulates a rapid increase in ecdysteroid hormone synthesis that is accompanied by general and specific increases in protein synthesis, including that of a 70 kDa cognate heat shock protein (hsc 70). To further understand the possible roles of hsc 70, hsc 70 cDNA clones were isolated from a tobacco hornworm (Manduca sexta) Prothoracic Gland cDNA library. All sequenced clones were highly homologous to the Drosophila hsc 70-4 isoform. Manduca hsc 70 mRNA levels during the last larval instar exhibited a peak at the onset of wandering and a peak that coincided with the major pre-metamorphic peak of ecdysteroid synthesis. Manipulations of the Glands' hormonal milieu showed that hsc 70 mRNA levels respond to 20-hydroxyecdysone, dibutyryl cAMP, PTTH and the JH analogue hydroprene. The protein and mRNA data suggest that hsc 70 could be involved in a negative feedback loop regulating assembly of the ecdysone receptor complex.
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Dynamic regulation of Prothoracic Gland ecdysteroidogenesis: Manduca sexta recombinant Prothoracicotropic hormone and brain extracts have identical effects.
Insect biochemistry and molecular biology, 2000Co-Authors: Lawrence I Gilbert, Akira Mizoguchi, Qisheng Song, Wendy A. Smith, Shinji Nagata, Robert Rybczynski, R Morreale, H Matubayashi, M Shionoya, Hiroshi KataokaAbstract:Multiple assays were conducted in order to determine if the recently available recombinant Prothoracicotropic hormone (rPTTH) from Manduca sexta is identical, or similar, to the natural hormone and if results from its use in a variety of assays confirm, or are inconsistent with, previous studies over the past 20years on PTTH action using brain extract. Brain extracts and rPTTH showed similar, if not identical, effects on the cell biology of Manduca Prothoracic Gland cells with the following results: increased levels of cAMP (adenosine 3':5' cyclic monophosphate) synthesis; requirement for extracellular Ca(2+) in in vitro studies; ecdysteroidogenesis stimulation in vitro; stimulation of general and specific protein synthesis; immunocytochemical identification of the two lateral cells in each brain hemisphere as the source of PTTH (the Prothoracicotropes); the ability of antibodies to rPTTH to inhibit ecdysteroidogenesis stimulation in vitro; and the multiple phosphorylation of the ribosomal protein S6. The data revealed that brain extract and rPTTH show equivalent effects in all of the assays, indicating that this rPTTH is the natural PTTH of Manduca and that the data generated with brain extracts over the past two decades are indeed relevant.
Qisheng Song - One of the best experts on this subject based on the ideXlab platform.
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Dynamic regulation of Prothoracic Gland ecdysteroidogenesis: Manduca sexta recombinant Prothoracicotropic hormone and brain extracts have identical effects.
Insect biochemistry and molecular biology, 2000Co-Authors: Lawrence I Gilbert, Akira Mizoguchi, Qisheng Song, Wendy A. Smith, Shinji Nagata, Robert Rybczynski, R Morreale, H Matubayashi, M Shionoya, Hiroshi KataokaAbstract:Multiple assays were conducted in order to determine if the recently available recombinant Prothoracicotropic hormone (rPTTH) from Manduca sexta is identical, or similar, to the natural hormone and if results from its use in a variety of assays confirm, or are inconsistent with, previous studies over the past 20years on PTTH action using brain extract. Brain extracts and rPTTH showed similar, if not identical, effects on the cell biology of Manduca Prothoracic Gland cells with the following results: increased levels of cAMP (adenosine 3':5' cyclic monophosphate) synthesis; requirement for extracellular Ca(2+) in in vitro studies; ecdysteroidogenesis stimulation in vitro; stimulation of general and specific protein synthesis; immunocytochemical identification of the two lateral cells in each brain hemisphere as the source of PTTH (the Prothoracicotropes); the ability of antibodies to rPTTH to inhibit ecdysteroidogenesis stimulation in vitro; and the multiple phosphorylation of the ribosomal protein S6. The data revealed that brain extract and rPTTH show equivalent effects in all of the assays, indicating that this rPTTH is the natural PTTH of Manduca and that the data generated with brain extracts over the past two decades are indeed relevant.
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Alterations in ultraspiracle (USP) content and phosphorylation state accompany feedback regulation of ecdysone synthesis in the insect Prothoracic Gland.
Insect biochemistry and molecular biology, 1998Co-Authors: Qisheng Song, Lawrence I GilbertAbstract:Insect molting and metamorphosis are elicited by a class of ecdysteroids, mainly 20-hydroxyecdysone (20E), the precursor of which is synthesized in the Prothoracic Gland. 20E acts via the ecdysone receptor (EcR) and its heterodimer partner ultraspiracle (USP). Analysis of the Prothoracic Gland of Manduca sexta revealed that the developmental expression and phosphorylation of a specific USP form, p47, is positively correlated with ecdysteroidogenesis and that 20E, but not ecdysone, is responsible for initiating the translational expression and phosphorylation of p47. The latter forms a functional complex with EcR and the ligand-complex interaction results in the down regulation of ecdysteroidogenesis and the inhibition of Prothoracicotropic hormone (PTTH)-stimulated ecdysteroidogenesis. The composite data suggest that USP plays a key role in modulating PTTH-stimulated ecdysteroid biosynthesis through the selective expression and phosphorylation of the p47 USP isoform.
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Control of ecdysteroidogenesis: Activation and inhibition of Prothoracic Gland activity
Invertebrate Neuroscience, 1997Co-Authors: Lawrence I Gilbert, Qisheng Song, Robert RybczynskiAbstract:The ecdysteroid hormones, mainly 20-hydroxyecdysone (20E), play a pivotal role in insect development by controlling gene expression involved in molting and metamorphosis. In the model insect Manduca sexta the production of ecdysteroids by the Prothoracic Gland is acutely controlled by a brain neurohormone, Prothoracicotropic hormone (PTTH). PTTH initiates a cascade of events that progresses from the influx of Ca^2+ and cAMP generation through phosphorylation of the ribosomal protein S6 and S6-dependent protein synthesis, and concludes with an increase in the synthesis and export of ecdysteroids from the Gland. Recent studies indicate that S6 phosphorylation probably controls the steroidogenic effect of PTTH by gating the translation of selected mRNAs whose protein products are required for increased ecdysteroid synthesis. Inhibition of S6 phosphorylation prevents an increase in PTTH-stimulated protein synthesis and subsequent ecdysteroid synthesis. Two of the proteins whose translations are specifically stimulated by PTTH have been identified, one being a β tubulin and the other a heat shock protein 70 family member. Current data suggest that these two proteins could be involved in supporting microtubule-dependent protein synthesis and ecdysone receptor assembly and/or function. Recent data also indicate that the 20E produced by the Prothoracic Gland feeds back upon the Gland by increasing expression and phosphorylation of a specific USP isoform that is a constituent of the functional ecdysone receptor. Changes in the concentration and composition of the ecdysone receptor complex of the Prothoracic Gland could modulate the Gland's potential for ecdysteroid synthesis (e.g. feedback inhibition) by controlling the levels of enzymes or other proteins in the ecdysteroid biosynthetic pathway.
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Molecular Cloning, Developmental Expression, and Phosphorylation of Ribosomal Protein S6 in the Endocrine Gland Responsible for Insect Molting
The Journal of biological chemistry, 1997Co-Authors: Qisheng Song, Lawrence I GilbertAbstract:Phosphorylation of ribosomal protein S6 is requisite for Prothoracicotropic hormone (PTTH)-stimulated specific protein synthesis and subsequent ecdysteroidogenesis in the Prothoracic Glands of the tobacco hornworm, Manduca sexta. To better understand the role of S6 in regulating ecdysteroidogenesis, S6 cDNA was isolated from a Manduca Prothoracic Gland cDNA library and sequenced. The deduced protein is comprised of 253 amino acids, has a molecular weight of 29,038, and contains four copies of a 10-amino acid motif defining potential DNA-binding sites. This Manduca S6 possesses a consensus recognition sequence for the p70(s6k) binding domain as well as six seryl residues at the carboxyl-terminal sequence of 17 amino acids. Phosphoamino acid analysis revealed that the phosphorylation of Manduca Prothoracic Gland S6 is limited exclusively to serine residues. Although alterations in the quantity of S6 mRNA throughout the last larval instar and early pupal-adult development were not well correlated with the hemolymph ecdysteroid titer, developmental expression and phosphorylation of S6 were temporally correlated with PTTH release and the hemolymph ecdysteroid titer. These data provide additional evidence that S6 phosphorylation is a critical element in the transduction pathway leading to PTTH-stimulated ecdysteroidogenesis.
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An immunophilin is a component of the insect ecdysone receptor (EcR) complex.
Insect Biochemistry and Molecular Biology, 1997Co-Authors: Qisheng Song, Emad S. Alnemri, Gerald Litwack, Lawrence I GilbertAbstract:Abstract The ecdysone receptor (EcR) complex has been identified in the Prothoracic Gland of Manduca sexta by specific immunoprecipitation and Western blot analyses, and includes EcR, ultraspiracle (USP) and FKBP46. The EcR complex binds ponasterone A in a dose-dependent manner with a K d of 7.04×10 −9 M. Immunocytochemistry revealed that EcR, USP and FKBP46 were localized within the nucleus of the Prothoracic Gland cells, and suggested that the developmental expression patterns of EcR and USP changed in concert with the hemolymph ecdysteroid titer whereas that of FKBP46 did not. The composite results suggest that the hemolymph ecdysteroid titer, of which 20 hydroxyecdysone is the major component, modulates the expression of both EcR and USP in the Prothoracic Gland to achieve feedback regulation.
Ryusuke Niwa - One of the best experts on this subject based on the ideXlab platform.
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poly a binding protein is required for nuclear localization of the ecdysteroidogenic transcription factor molting defective in the Prothoracic Gland of drosophila melanogaster
Frontiers in Genetics, 2020Co-Authors: Takumi Kamiyama, Wei Sun, Naoki Tani, Akira Nakamura, Ryusuke NiwaAbstract:Steroid hormone signaling contributes to the development of multicellular organisms. In insects, ecdysteroids, like ecdysone and the more biologically-active derivative 20-hydroxyecdysone (20E), promote molting and metamorphosis. Ecdysone is biosynthesized in the Prothoracic Gland (PG), via several steps catalyzed by ecdysteroidogenic enzymes that are encoded by Halloween genes. The spatio-temporal expression pattern of ecdysteroidogenic genes is strictly controlled, resulting in a proper fluctuation of the 20E titer during insect development. However, their transcriptional regulatory mechanism is still elusive. A previous study has found that the polyadenylated tail [poly(A)] deadenylation complex, called Carbon catabolite repressor 4-Negative on TATA (CCR4-NOT) regulates the expression of spookier (spok), which encodes one of the ecdysteroidogenic enzymes in the fruit fly Drosophila melanogaster. Based on this finding, we speculated whether any other poly(A)-related protein also regulates spok expression. In this study, we reported that poly(A) binding protein (Pabp) is involved in spok expression by regulating nuclear localization of the transcription factor molting defective (Mld). When pabp was knocked down specifically in the PG by transgenic RNAi, both spok mRNA and Spok protein levels were significantly reduced. In addition, the spok promoter-driven green fluorescence protein (GFP) signal was also reduced in the pabp-RNAi PG, suggesting that Pabp is involved in the transcriptional regulation of spok. We next examined which transcription factors are responsible for Pabp-dependent transcriptional regulation. Among the transcription factors acting in the PG, we primarily focused on the zinc-finger transcription factor Mld, as Mld is essential for spok transcription. Mld was localized in the nucleus of the control PG cells, while Mld abnormally accumulated in the cytoplasm of pabp-RNAi PG cells. In contrast, pabp-RNAi did not affect the nuclear localization of other transcription factors, including ventral vein lacking (Vvl) and POU domain motif 3 (Pdm3), in PG cells. From these results, we propose that Pabp regulates subcellular localization in the PG, specifically of the transcription factor Mld, in the context of ecdysone biosynthesis.
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autocrine regulation of ecdysone synthesis by β3 octopamine receptor in the Prothoracic Gland is essential for drosophila metamorphosis
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Ryusuke Niwa, Yuya Ohhara, Yuko Shimadaniwa, Yasunari Kayashima, Yoshiki Hayashi, Kazutaka Akagi, Hitoshi Ueda, Kimiko YamakawakobayashiAbstract:In Drosophila, pulsed production of the steroid hormone ecdysone plays a pivotal role in developmental transitions such as metamorphosis. Ecdysone production is regulated in the Prothoracic Gland (PG) by Prothoracicotropic hormone (PTTH) and insulin-like peptides (Ilps). Here, we show that monoaminergic autocrine regulation of ecdysone biosynthesis in the PG is essential for metamorphosis. PG-specific knockdown of a monoamine G protein-coupled receptor, β3-octopamine receptor (Octβ3R), resulted in arrested metamorphosis due to lack of ecdysone. Knockdown of tyramine biosynthesis genes expressed in the PG caused similar defects in ecdysone production and metamorphosis. Moreover, PTTH and Ilps signaling were impaired by Octβ3R knockdown in the PG, and activation of these signaling pathways rescued the defect in metamorphosis. Thus, monoaminergic autocrine signaling in the PG regulates ecdysone biogenesis in a coordinated fashion on activation by PTTH and Ilps. We propose that monoaminergic autocrine signaling acts downstream of a body size checkpoint that allows metamorphosis to occur when nutrients are sufficiently abundant.
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Serotonergic neurons respond to nutrients and regulate the timing of steroid hormone biosynthesis in Drosophila
Nature Communications, 2014Co-Authors: Yuko Shimada-niwa, Ryusuke NiwaAbstract:Steroidal hormones play a major role in the transition from juvenile-to-adult stages of development. Here, Shimada-Niwa and Niwa show that production of one such hormone in the Prothoracic Gland of Drosophila melanogaster , is regulated by a subset of serotonergic neurons innervating the Prothoracic Gland. The temporal transition of development is flexibly coordinated in the context of the nutrient environment, and this coordination is essential for organisms to increase their survival fitness and reproductive success. Steroid hormone, a key player of the juvenile-to-adult transition, is biosynthesized in a nutrient-dependent manner; however, the underlying genetic mechanism remains unclear. Here we report that the biosynthesis of insect steroid hormone, ecdysteroid, is regulated by a subset of serotonergic neurons in Drosophila melanogaster . These neurons directly innervate the Prothoracic Gland (PG), an ecdysteroid-producing organ and share tracts with the stomatogastric nervous system. Interestingly, the projecting neurites morphologically respond to nutrient conditions. Moreover, reduced activity of the PG-innervating neurons or of serotonin signalling in the PG strongly correlates with a delayed developmental transition. Our results suggest that serotonergic neurons form a link between the external environment and the internal endocrine system by adaptively tuning the timing of steroid hormone biosynthesis.
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transcriptional control of steroid biosynthesis genes in the drosophila Prothoracic Gland by ventral veins lacking and knirps
PLOS Genetics, 2014Co-Authors: Thomas E Danielsen, Ryusuke Niwa, Morten E Moeller, Elad Dorry, Tatsuya Komurakawa, Yoshinori Fujimoto, Jesper T Troelsen, Rachel Herder, Michael B Oconnor, Kim F RewitzAbstract:Specialized endocrine cells produce and release steroid hormones that govern development, metabolism and reproduction. In order to synthesize steroids, all the genes in the biosynthetic pathway must be coordinately turned on in steroidogenic cells. In Drosophila, the steroid producing endocrine cells are located in the Prothoracic Gland (PG) that releases the steroid hormone ecdysone. The transcriptional regulatory network that specifies the unique PG specific expression pattern of the ecdysone biosynthetic genes remains unknown. Here, we show that two transcription factors, the POU-domain Ventral veins lacking (Vvl) and the nuclear receptor Knirps (Kni), have essential roles in the PG during larval development. Vvl is highly expressed in the PG during embryogenesis and is enriched in the Gland during larval development, suggesting that Vvl might function as a master transcriptional regulator in this tissue. Vvl and Kni bind to PG specific cis-regulatory elements that are required for expression of the ecdysone biosynthetic genes. Knock down of either vvl or kni in the PG results in a larval developmental arrest due to failure in ecdysone production. Furthermore, Vvl and Kni are also required for maintenance of TOR/S6K and Prothoracicotropic hormone (PTTH) signaling in the PG, two major pathways that control ecdysone biosynthesis and PG cell growth. We also show that the transcriptional regulator, Molting defective (Mld), controls early biosynthetic pathway steps. Our data show that Vvl and Kni directly regulate ecdysone biosynthesis by transcriptional control of biosynthetic gene expression and indirectly by affecting PTTH and TOR/S6K signaling. This provides new insight into the regulatory network of transcription factors involved in the coordinated regulation of steroidogenic cell specific transcription, and identifies a new function of Vvl and Knirps in endocrine cells during post-embryonic development.
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A Basic-HLH Transcription Factor, HLH54F, Is Highly Expressed in the Prothoracic Gland in the Silkworm Bombyx mori and the Fruit Fly Drosophila melanogaster
Bioscience biotechnology and biochemistry, 2009Co-Authors: Toshiki Namiki, Ryusuke Niwa, Atsushi Higuchi, Takuji Yoshiyama, Kazuei Mita, Hiroshi KataokaAbstract:We describe our findings on HLH54F, a basic helix-loop-helix transcription factor gene that was highly expressed in the Prothoracic Gland, an organ producing the insect steroid ecdysone. HLH54F was uncovered by the use of an expressed sequence tag database of the silkworm Bombyx mori. It was also highly expressed in the Prothoracic Gland of the fruit fly Drosophila melanogaster.
