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Norihisa Fujita - One of the best experts on this subject based on the ideXlab platform.
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Efficient folding of the insect neuropeptide Eclosion Hormone by protein disulfide isomerase.
Journal of biochemistry, 2001Co-Authors: Norihisa Fujita, Masanori YoshidaAbstract:Eclosion Hormone is an insect neuropeptide that consists of 62 amino acid residues including three disulfide bonds. We have previously reported its hypothetical 3D structure consisting mainly of three alpha-helices. In this paper, we report the effects of chaperone proteins on the refolding of denatured Eclosion Hormone in a redox buffer containing reduced and oxidized glutathione. Urea-denatured Eclosion Hormone was spontaneously reactivated within 1 min with a yield of more than 90%, while beta-mercaptoethanol-denatured Eclosion Hormone was reactivated in a few minutes with a yield of 75%. Under the same experimental conditions, Eclosion Hormone treated with beta-mercaptoethanol and urea was reactivated slowly with a yield of 47% over a period of 2 h. Protein disulfide isomerase, a eucaryotic chaperone protein, markedly increased the reactivation yield and rate of the totally denatured Hormone. GroE oligomers slightly improved the reactivation yield but peptidyl prolyl isomerase had no influence on yield or rate. We propose that the folding pathway of Eclosion Hormone involves at least two rate-limiting steps, and that protein disulfide isomerase is likely to be involved in the folding in insect neuronal cells.
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Efficient Folding of the Insect Neuropeptide Eclosion Hormone by Protein Disulfide Isomerase1
2001Co-Authors: Norihisa Fujita, Masanori YoshidaAbstract:Eclosion Hormone is an insect neuropeptide that consists of 62 amino acid residues including three disulfide bonds. We have previously reported its hypothetical 3D struc-ture consisting mainly of three a-helices. In this paper, we report the effects of chaper-one proteins on the refolding of denatured Eclosion Hormone in a redox buffer containing reduced and oxidized glutathione. Urea-denatured Eclosion Hormone was spontaneously reactivated within 1 min with a yield of more than 90%, while [J-mercap-toethanol-denatured Eclosion Hormone was reactivated in a few minutes with a yield of 75%. Under the same experimental conditions, Eclosion Hormone treated with p-mercap-toethanol and urea was reactivated slowly with a yield of 47 % over a period of 2 h. Pro-tein disuLfide isomerase, a eucaryotic chaperone protein, markedly increased the re-activation yield and rate of the totally denatured Hormone. GroE oligomers slightly improved the reactivation yield but peptidyl prolyl isomerase had no influence on yield or rate. We propose that the folding pathway of Eclosion Hormone involves at least two rate-limiting steps, and that protein disulfide isomerase is likely to be involved in the folding in insect neuronal cells
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the functional residues and their representation by a hypothetical 3d model of silkworm Eclosion Hormone
Protein Engineering, 1998Co-Authors: Norihisa Fujita, Takashi Maekawa, Satoshi Ohta, Takeshi KikuchiAbstract:1 To whom correspondence should be addressed We have previously reported that an insect neuropeptide, Eclosion Hormone contained an a-helix in the N-terminal region and the helix was likely to play an important role in constructing an active globular structure. Furthermore, Met24 and Phe25 were found to be indispensable for the biological activity. On the other hand, no strict structure at the C-terminal side was found. In this paper, we predicted the secondary structure in the C-terminal side and analyzed the functional residues by a Gly-substitution technique. As a result, we speculated that the Eclosion Hormone contains three a-helices throughout the molecule which are essential for an active peptide structure. Moreover, we found four residues important for the biological activity of silkworm Eclosion Hormone: Phe29, Ile55, Phe58 and Leu59. In order to understand these results stereochemically, we have constructed a 3D structure using computer aided molecular modelling. The hypothetical 3D model showed that Phe25 and Phe58 interact together in a hydrophobic manner to keep a globular form. Met24, Phe29, and Ile55 are exposed to solvent to have a hydrophobic interaction with an Eclosion Hormone receptor. Leu59 can also play an important role by forming a functional conformation with Phe29 and Ile55.
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structural study on silkworm Eclosion Hormone fragment 1 34 in solution by proton nuclear magnetic resonance spectroscopy
Bioorganic & Medicinal Chemistry, 1998Co-Authors: Atsuko Y Nosaka, Michihiro Takai, Ichiro Umemura, Kenji Kanaori, Norihisa FujitaAbstract:Abstract Eclosion Hormone (EH) is a neuropeptide Hormone which controls the ecdysis behavior in insect. The three dimensional structure of the N-terminal fragment (1–34) of the Eclosion Hormone which was predicted to contain a compact region crucial for the EH activity was studied in 50% d 3 -trifluoroethanol(TFE)/50% H 2 O at pH 3 and 298 K by 1 H NMR spectroscopy with the combined use of distance geometry and molecular dynamics calculations. NMR results indicated that the fragment actually assumes an α-helix between Ala10 and Gln20, but no rigid structure is present from Cys21 through the C-terminus and for the N-terminal region (Ser1–Asp9). The elucidated structure was compared with the predicted structure of the native EH for the further development of the design of the insecticide.
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prediction of the biologically active sites in Eclosion Hormone from the silkworm bombyx mori
Protein Engineering, 1997Co-Authors: Takeshi Kikuchi, Michihiro Takai, Megumi Okamoto, Martin Geiser, Albert Schmitz, Keigo Gohda, Takeshi Morita, Kenichi Horii, Norihisa FujitaAbstract:The structure-activity relationship of Eclosion Hormone from the silkworm, Bombyx mori, was analyzed. First, the probable active residues in silkworm Eclosion Hormone and also tobacco hornworm Eclosion Hormone were predicted by the average distance map method. To examine the contributions of those residues to the activity of silkworm Eclosion Hormone, Gly-substituted mutants for those predicted residues were produced by site-directed mutagenesis and their activities were evaluated by a bioassay. Finally, Glu12, Met24 and Phe25 were estimated to be the crucial residues for the Eclosion Hormone activity. The possibility of the development of a blocker of an Eclosion Hormone receptor on the basis of the present work is also discussed.
Michael E Adams - One of the best experts on this subject based on the ideXlab platform.
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receptor guanylyl cyclases in inka cells targeted by Eclosion Hormone
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Jercherng Chang, Rueybing Yang, Michael E AdamsAbstract:A signature of Eclosion Hormone (EH) action in insect ecdysis is elevation of cGMP in Inka cells, leading to massive release of ecdysis triggering Hormone (ETH) and ecdysis initiation. Although this aspect of EH-induced signal transduction is well known, the receptor mediating this process has not been identified. Here, we describe a receptor guanylyl cyclase BdmGC-1 and its isoform BdmGC-1B in the Oriental fruit fly Bactrocera dorsalis that are activated by EH. The B form exhibits the conserved domains and putative N-glycosylation sites found in BdmGC-1, but possesses an additional 46-amino acid insertion in the extracellular domain and lacks the C-terminal tail of BdmGC-1. Combined immunolabeling and in situ hybridization reveal that BdmGC-1 is expressed in Inka cells. Heterologous expression of BdmGC-1 in HEK cells leads to robust increases in cGMP following exposure to low picomolar concentrations of EH. The B-isoform responds only to higher EH concentrations, suggesting different physiological roles of these cyclases. We propose that BdmGC-1 and BdmGC-1Β are high- and low-affinity EH receptors, respectively.
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Identification, developmental expression, and functions of bursicon in the tobacco hawkmoth, Manduca sexta.
The Journal of comparative neurology, 2008Co-Authors: Li Dai, Hanswilli Honegger, Elizabeth M Dewey, Ching-wei Luo, Michael E AdamsAbstract:During postEclosion, insects undergo sequential processes of wing expansion and cuticle tanning. Bursicon, a highly conserved neuroHormone implicated in regulation of these processes, was characterized recently as a heterodimeric cystine knot protein in Drosophila melanogaster. Here we report the predicted precursor sequences of bursicon subunits (Masburs and Maspburs) in the moth Manduca sexta. Distinct developmental patterns of mRNA transcript and subunit-specific protein labeling of burs and pburs as well as crustacean cardioactive peptide in neurons of the ventral nervous system were observed in pharate larval, pupal, and adult stages. A subset of bursicon neurons located in thoracic ganglia of larvae expresses ecdysis-triggering Hormone (ETH) receptors, suggesting that they are direct targets of ETH. Projections of bursicon neurons within the CNS and to neurohemal secretory sites are consistent with both central signaling and circulatory Hormone functions. Intrinsic cells of the corpora cardiaca contain pburs transcripts and pburs-like immunoreactivity, whereas burs transcripts and burs-like immunoreactivity were absent in these cells. Recombinant bursicon induces both wing expansion and tanning, whereas synthetic Eclosion Hormone induces only wing expansion.
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central peptidergic ensembles associated with organization of an innate behavior
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Young-joon Kim, Akira Mizoguchi, Kookho Cho, Michael E AdamsAbstract:At the end of each developmental stage, insects perform the ecdysis sequence, an innate behavior necessary for shedding the old cuticle. Ecdysis triggering Hormones (ETHs) initiate these behaviors through direct actions on the CNS. Here, we identify the ETH receptor (ETHR) gene in the moth Manduca sexta, which encodes two subtypes of GPCR (ETHR-A and ETHR-B). Expression of ETHRs in the CNS coincides precisely with acquisition of CNS sensitivity to ETHs and behavioral competence. ETHR-A occurs in diverse networks of neurons, producing both excitatory and inhibitory neuropeptides, which appear to be downstream signals for behavior regulation. These peptides include allatostatins, crustacean cardioactive peptide (CCAP), calcitonin-like diuretic Hormone, CRF-like diuretic Hormones (DHs) 41 and 30, Eclosion Hormone, kinins, myoinhibitory peptides (MIPs), neuropeptide F, and short neuropeptide F. In particular, cells L3,4 in abdominal ganglia coexpress kinins, DH41, and DH30, which together elicit the fictive preecdysis rhythm. Neurons IN704 in abdominal ganglia coexpress CCAP and MIPs, whose joint actions initiate the ecdysis motor program. ETHR-A also is expressed in brain ventromedial cells, whose release of EH increases excitability in CCAP/MIP neurons. These findings provide insights into how innate, centrally patterned behaviors can be orchestrated via recruitment of peptide cotransmitter neurons.
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a command chemical triggers an innate behavior by sequential activation of multiple peptidergic ensembles
Current Biology, 2006Co-Authors: Giovanni C Galizia, Dušan Žitňan, Kookho Cho, Michael E AdamsAbstract:Summary Background: At the end of each molt, insects shed their old cuticle by performing the ecdysis sequence, an innate behavior consisting of three steps: pre-ecdysis, ecdysis, and postecdysis. Blood-borne ecdysis-triggering Hormone (ETH) activates the behavioral sequence through direct actions on the central nervous system. Results: To elucidate neural substrates underlying the ecdysis sequence, we identified neurons expressing ETH receptors (ETHRs) in Drosophila. Distinct ensembles of ETHR neurons express numerous neuropeptides including kinin, FMRFamides, Eclosion Hormone (EH), crustacean cardioactive peptide (CCAP), myoinhibitory peptides (MIP), and bursicon. Real-time imaging of intracellular calcium dynamics revealed sequential activation of these ensembles after ETH action. Specifically, FMRFamide neurons are activated during pre-ecdysis; EH, CCAP, and CCAP/MIP neurons are active prior to and during ecdysis; and activity of CCAP/MIP/bursicon neurons coincides with postecdysis. Targeted ablation of specific ETHR ensembles produces behavioral deficits consistent with their proposed roles in the behavioral sequence. Conclusions: Our findings offer novel insights into how a command chemical orchestrates an innate behavior by stepwise recruitment of central peptidergic ensembles.
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signal transduction in Eclosion Hormone induced secretion of ecdysis triggering Hormone
Journal of Biological Chemistry, 2001Co-Authors: Timothy G Kingan, Richard A Cardullo, Michael E AdamsAbstract:Inka cells of insect epitracheal glands (EGs) secrete preecdysis and ecdysis-triggering Hormones (PETH and ETH) at the end of each developmental stage. Both peptides act in the central nervous system to evoke the ecdysis behavioral sequence, a stereotype behavior during which old cuticle is shed. Secretion of ETH is stimulated by a brain neuropeptide, Eclosion Hormone (EH). EH evokes accumulation of cGMP followed by release of ETH from Inka cells, and exogenous cGMP evokes secretion of ETH. The secretory responses to EH and cGMP are inhibited by the broad-spectrum kinase inhibitor staurosporine, and the response to EH is potentiated by the phosphatase inhibitor calyculin A. Staurosporine did not inhibit EH-evoked accumulation of cGMP. Changes in cytoplasmic Ca2+ in Inka cells during EH signaling were monitored via fluorescence ratioing with fura-2-loaded EGs. Cytoplasmic Ca2+ increases within 30–120 s after addition of EH to EGs, and it remains elevated for at least 10 min, corresponding with the time course of secretion. Secretion is increased in dose-dependent manner by the Ca2+-ATPase inhibitor thapsigargin, a treatment that does not elevate glandular cGMP above basal levels. The secretory response to EH is partially inhibited in glands loaded with EGTA, while cGMP levels are unaffected. These findings suggest that EH activates second messenger cascades leading to cGMP accumulation and Ca2+mobilization and/or influx and that both pathways are required for a full secretory response. cGMP activates a staurosporine-inhibitable protein kinase. We propose that Ca2+ acts via a parallel cascade with a time course that is similar to that for cGMP activation of a cGMP-dependent protein kinase.
David B. Morton - One of the best experts on this subject based on the ideXlab platform.
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Cellular signaling in Eclosion Hormone action.
Journal of insect physiology, 2002Co-Authors: David B. Morton, P. Jeanette SimpsonAbstract:Abstract Eclosion Hormone (EH) is a 62 amino acid neuropeptide that plays an integral role in triggering ecdysis behavior at the end of each molt. At least three populations of cells are thought to be targets for EH, each of which show an EH-stimulated increase in the intracellular messenger guanosine 3′, 5′ cyclic monophosphate (cGMP). These EH target cells are believed to include two pairs of neurons in each of the ganglia of the ventral nerve cord (VNC) that contain the neuropeptide crustacean cardioactive peptide (CCAP), the Inka cells of the peripheral epitracheal glands and intrinsic non-neuronal cells in the abdominal transverse nerves. This review describes likely signaling cascades that result in the EH-stimulated cGMP increase. Several lines of evidence suggest the involvement of a novel nitric oxide insensitive soluble guanylyl cyclase (GC). A novel GC with these properties has recently been identified and we also present evidence to suggest that it is activated by EH and describe possible pathways for its activation. In addition, we review our current knowledge on the cellular and molecular events that take place downstream of the increase in cGMP.
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identification of the cellular target for Eclosion Hormone in the abdominal transverse nerves of the tobacco hornworm manduca sexta
The Journal of Comparative Neurology, 2000Co-Authors: Sharon Elaine Hesterlee, David B. MortonAbstract:The isolated abdominal central nervous system of Manduca sexta undergoes an increase in cyclic GMP (cGMP) when exposed to the insect peptide Eclosion Hormone (EH) before pupal ecdysis. Previously, cGMP immunocytochemistry revealed that the EH-stimulated increase in cGMP was contained in numerous filamentous processes within the transverse nerve associated with each abdominal ganglion. These processes seemed to be the axons of neurosecretory cells projecting to this neurohemal organ. In the present paper, we now show that the EH-stimulated cGMP is not present in neurosecretory terminals. There is no colocalization of the EH-stimulated cGMP with immunoreactivity of two peptides, known to be present in axons in the transverse nerves. Furthermore, there is no colocalization of EH-stimulated cGMP with the synaptic vesicle protein, synaptotagmin. The neurosecretory axons are localized to a narrow band at the anterior margin of the transverse nerve, whereas the cellular elements showing an EH-stimulated cGMP increase are primarily present in the posterior region. There are two cell types in this region: a granular and a nongranular type. The cGMP immunoreactivity seems to be contained within the nongranular type. During adult development, the cells of the posterior compartment spread in a thin layer between the transverse and dorsal nerves, become positive for myosin immunoreactivity between pupal stages 5 and 8, and seem to form the adult ventral diaphragm muscles. We conclude that the EH-sensitive filaments in the transverse nerves of Manduca are most likely to be intrinsic cells that subsequently develop into the ventral diaphragm muscles of the adult. J. Comp. Neurol. 424:339–355, 2000. © 2000 Wiley-Liss, Inc.
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effect of cycloheximide on Eclosion Hormone sensitivity and the developmental appearance of the Eclosion Hormone and cgmp regulated phosphoproteins in the cns of the tobacco hornworm manduca sexta
Journal of Receptors and Signal Transduction, 1995Co-Authors: David B. MortonAbstract:AbstractThe neuropeptide, Eclosion Hormone (EH), triggers ecdysis behavior at the end of each molt in Manduca sexta. Previous studies have shown that the action of EH is mediated by an increase in cGMP and is associated with the phosphorylation of two proteins, named the EGPs. The ability of insects to respond to EH is developmentally regulated with sensitivity being first seen at about 8 hr prior to the normal time of ecdysis. The EGPs are also first detectable in the CNS at 8 hr prior to ecdysis, suggesting that it is their synthesis which determines EH sensitivity.The protein synthesis inhibitor, cycloheximide was used to study the development of the events leading to pupal ecdysis in Manduca. The results of these experiments suggest that protein synthesis is necessary about 10 hr before ecdysis for both the development of EH sensitivity and for the appearance of the EGPs.
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Eclosion Hormone stimulates cyclic gmp levels in manduca sexta nervous tissue via arachidonic acid metabolism with little or no contribution from the production of nitric oxide
Journal of Neurochemistry, 1992Co-Authors: David B. Morton, Michael A GiuntaAbstract:: The neuropeptide Eclosion Hormone acts directly on the nervous system of the tobacco hornworm, Manduca sexta, to trigger ecdysis behavior at the end of each molt. Previous studies have shown that the action of Eclosion Hormone is mediated via the intracellular messenger cyclic GMP. In the present study we have investigated the mechanisms involved in the Eclosion Hormone-stimulated increases in cyclic GMP. No stimulation of guanylate cyclase was seen in homogenized nervous tissue, suggesting that Eclosion Hormone does not directly stimulate a membranebound form of guanylate cyclase. Nitric oxide synthase inhibitors, N-methylarginine and nitroarginine, had no effect on Eclosion Hormone-stimulated cyclic GMP levels. By contrast, 4-bromophenacyl bromide, an inhibitor of arachidonic acid release, and nordihydroguaiaretic acid, an inhibitor of arachidonic acid metabolism, almost completely abolished the Eclosion Hormone-stimulated cyclic GMP increase. We hypothesize that Eclosion Hormone receptors are coupled to a lipase, activation of which causes the release of arachidonic acid. Either the arachidonic acid directly stimulates the soluble guanylate cyclase or further metabolism of arachidonic acid yields compounds that activate guanylate cyclase.
Michihiro Takai - One of the best experts on this subject based on the ideXlab platform.
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structural study on silkworm Eclosion Hormone fragment 1 34 in solution by proton nuclear magnetic resonance spectroscopy
Bioorganic & Medicinal Chemistry, 1998Co-Authors: Atsuko Y Nosaka, Michihiro Takai, Ichiro Umemura, Kenji Kanaori, Norihisa FujitaAbstract:Abstract Eclosion Hormone (EH) is a neuropeptide Hormone which controls the ecdysis behavior in insect. The three dimensional structure of the N-terminal fragment (1–34) of the Eclosion Hormone which was predicted to contain a compact region crucial for the EH activity was studied in 50% d 3 -trifluoroethanol(TFE)/50% H 2 O at pH 3 and 298 K by 1 H NMR spectroscopy with the combined use of distance geometry and molecular dynamics calculations. NMR results indicated that the fragment actually assumes an α-helix between Ala10 and Gln20, but no rigid structure is present from Cys21 through the C-terminus and for the N-terminal region (Ser1–Asp9). The elucidated structure was compared with the predicted structure of the native EH for the further development of the design of the insecticide.
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prediction of the biologically active sites in Eclosion Hormone from the silkworm bombyx mori
Protein Engineering, 1997Co-Authors: Takeshi Kikuchi, Michihiro Takai, Megumi Okamoto, Martin Geiser, Albert Schmitz, Keigo Gohda, Takeshi Morita, Kenichi Horii, Norihisa FujitaAbstract:The structure-activity relationship of Eclosion Hormone from the silkworm, Bombyx mori, was analyzed. First, the probable active residues in silkworm Eclosion Hormone and also tobacco hornworm Eclosion Hormone were predicted by the average distance map method. To examine the contributions of those residues to the activity of silkworm Eclosion Hormone, Gly-substituted mutants for those predicted residues were produced by site-directed mutagenesis and their activities were evaluated by a bioassay. Finally, Glu12, Met24 and Phe25 were estimated to be the crucial residues for the Eclosion Hormone activity. The possibility of the development of a blocker of an Eclosion Hormone receptor on the basis of the present work is also discussed.
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Eclosion Hormone-mediated signal transduction in the silkworm abdominal ganglia: involvement of a cascade from inositol(1,4,5)trisphosphate to cyclic GMP.
Biochemical and biophysical research communications, 1994Co-Authors: Yasuhiko Shibanaka, Hideaki Hayashi, Michihiro Takai, Ichiro Umemura, Y. Fujisawa, M. Okamoto, Norihisa FujitaAbstract:The neuropeptide Eclosion Hormone triggers ecdysis behavior in lepidopteran insects. We have previously shown that the Eclosion Hormone stimulates the formation of two intracellular second messengers, cGMP and inositol(1,4,5)trisphosphate in the abdominal ganglia of Bombyx mori. In order to elucidate the intracellular signaling pathway involving these second messengers, we studied the Eclosion Hormone-mediated signal transduction using saponin-treated abdominal ganglia.We obtained the following results; i) Eclosion Hormone activated nitric oxide synthase, ii) the Eclosion Hormone-induced cGMP increase was inhibited by various enzyme inhibitors such as NG-nitro-arginine; a nitric oxide synthase inhibitor, EGTA; a calcium chelating reagent, W-5; a calmodulin inhibitor and compound 48/80; a phospholipase C inhibitor and iii) the inositol(1,4,5)-trisphosphate stimulated the formation of cGMP, in the Bombyx abdominal ganglia. Based on these findings we tentatively propose a hypothetical pathway: The signal initially triggered by Eclosion Hormone and Eclosion Hormone receptor complex induces activation of phospholipase C which produces inositol(l,4,5)trisphosphate. Inositol(I,4,5)trisphosphate increases intracellular Ca2+, followed by subsequent activation of nitric oxide syrithase through the formation of Ca2+-calmodulin complex. The reaction product, nitric oxide acts on soluble guanylate cyclase to stimulate cGMP formation which induces the ecdysis behavior in Bombyx pharate adults.
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Eclosion Hormone activates phosphatidylinositol hydrolysis in silkworm abdominal ganglia during adult metamorphosis.
European journal of biochemistry, 1993Co-Authors: Yasuhiko Shibanaka, Hideaki Hayashi, Michihiro Takai, Norihisa FujitaAbstract:Eclosion Hormone (EH), an insect neuropeptide, stimulated phosphatidylinositol (PtdIns) hydrolysis in abdominal ganglia isolated from Bombyx mori in a specific stage of adult development. Incubation of abdominal ganglia from silkworm pharate adults with EH led to an increase in formation of inositol 1,4,5-trisphosphate but this increase took place transiently, maximum increase being observed 30 s after the addition of EH. PtdIns hydrolysis was stimulated by exogenous EH in a dose-dependent fashion and was completely abolished by the phospholipase C inhibitors, neomycin and compound 48/80. The EH-induced PtdIns hydrolysis developed in parallel to the EH-induced Eclosion behaviour during development of the adult. These results suggest that the EH-stimulated PtdIns Hydrolysis plays an important role in EH-mediated signal transduction during adult development of B. mori.
Yasuhiko Shibanaka - One of the best experts on this subject based on the ideXlab platform.
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Eclosion Hormone-mediated signal transduction in the silkworm abdominal ganglia: involvement of a cascade from inositol(1,4,5)trisphosphate to cyclic GMP.
Biochemical and biophysical research communications, 1994Co-Authors: Yasuhiko Shibanaka, Hideaki Hayashi, Michihiro Takai, Ichiro Umemura, Y. Fujisawa, M. Okamoto, Norihisa FujitaAbstract:The neuropeptide Eclosion Hormone triggers ecdysis behavior in lepidopteran insects. We have previously shown that the Eclosion Hormone stimulates the formation of two intracellular second messengers, cGMP and inositol(1,4,5)trisphosphate in the abdominal ganglia of Bombyx mori. In order to elucidate the intracellular signaling pathway involving these second messengers, we studied the Eclosion Hormone-mediated signal transduction using saponin-treated abdominal ganglia.We obtained the following results; i) Eclosion Hormone activated nitric oxide synthase, ii) the Eclosion Hormone-induced cGMP increase was inhibited by various enzyme inhibitors such as NG-nitro-arginine; a nitric oxide synthase inhibitor, EGTA; a calcium chelating reagent, W-5; a calmodulin inhibitor and compound 48/80; a phospholipase C inhibitor and iii) the inositol(1,4,5)-trisphosphate stimulated the formation of cGMP, in the Bombyx abdominal ganglia. Based on these findings we tentatively propose a hypothetical pathway: The signal initially triggered by Eclosion Hormone and Eclosion Hormone receptor complex induces activation of phospholipase C which produces inositol(l,4,5)trisphosphate. Inositol(I,4,5)trisphosphate increases intracellular Ca2+, followed by subsequent activation of nitric oxide syrithase through the formation of Ca2+-calmodulin complex. The reaction product, nitric oxide acts on soluble guanylate cyclase to stimulate cGMP formation which induces the ecdysis behavior in Bombyx pharate adults.
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Eclosion Hormone activates phosphatidylinositol hydrolysis in silkworm abdominal ganglia during adult metamorphosis.
European journal of biochemistry, 1993Co-Authors: Yasuhiko Shibanaka, Hideaki Hayashi, Michihiro Takai, Norihisa FujitaAbstract:Eclosion Hormone (EH), an insect neuropeptide, stimulated phosphatidylinositol (PtdIns) hydrolysis in abdominal ganglia isolated from Bombyx mori in a specific stage of adult development. Incubation of abdominal ganglia from silkworm pharate adults with EH led to an increase in formation of inositol 1,4,5-trisphosphate but this increase took place transiently, maximum increase being observed 30 s after the addition of EH. PtdIns hydrolysis was stimulated by exogenous EH in a dose-dependent fashion and was completely abolished by the phospholipase C inhibitors, neomycin and compound 48/80. The EH-induced PtdIns hydrolysis developed in parallel to the EH-induced Eclosion behaviour during development of the adult. These results suggest that the EH-stimulated PtdIns Hydrolysis plays an important role in EH-mediated signal transduction during adult development of B. mori.
