The Experts below are selected from a list of 333 Experts worldwide ranked by ideXlab platform

Hironori Ishizaki - One of the best experts on this subject based on the ideXlab platform.

  • molecular characterization of the brain secretory peptides prothoracicotropic hormone ptth and Bombyxin of the silkmoth bombyx mori
    Proceedings of the Japan Academy. Series B Physical and Biological Sciences, 2004
    Co-Authors: Hironori Ishizaki
    Abstract:

    Molecular characterization of the brain secretory peptides, PTTH and Bombyxin, of Bombyx mori is reviewed. PTTH is a 30-kDa homodimeric glycoprotein, the monomer of which consists of 109 amino acids. Two monomers are held together by a disulfide bond. cDNA and gene coding for PTTH were cloned and the precursor protein for PTTH monomer was deduced. A novel 5-kD brain secretory peptide named Bombyxin has been discovered from Bombyx brain. Bombyxin is highly homologous to vertebrate insulin-family peptides and possesses the prothoracicotropic activity when injected into brain-removed pupae of a heterologous moth, Samia cynthia ricini, though inactive to Bombyx from which it was derived. cDNA and gene coding for Bombyxin were cloned, preproBombyxin protein was deduced, and posttranslational processing to generate mature Bombyxin was suggested. The Bombyx genome contains highly multiple copies of the gene coding for Bombyxins. Immunohistochemically, PTTH- and Bombyxin-producing brain neurosecretory cells were identified. (Communicated by Saburo TAMURA, M.J.A.)

  • three dimensional structure and receptor recognition sites of Bombyxin ii an insulin like brain secretory peptide of the silkmoth
    1999
    Co-Authors: Koji Nagata, Hiroshi Kataoka, Hironori Ishizaki, Minoru Tanaka, Hideki Hatanaka, Daisuke Kohda, K Momomura, K Tamori, Takashi Kadowaki, H. Nagasawa
    Abstract:

    K. NAGATA1,2 , H. HATANAKA1 , D. KOHDA1 , H. ISHIZAKI3 , K. MOMOMURA4 , K. TAMORI4 , T. KADOWAKI4 , M. TANAKA2 , H. KATAOKA2 , H. NAGASAWA2 , A. ISOGAI2 , A. SUZUKI2 and F. INAGAKI1 1 Department of Molecular Physiology, The Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan 2 Department of Agricultural Chemistry, The University of Tokyo, Tokyo, Japan 3 Department of Biology, Nagoya University, Nagoya, Japan 4 The Third Department of Internal Medicine, The University of Tokyo, Tokyo, Japan

  • Bombyxin, an insulin-related peptide of insects, reduces the major storage carbohydrates in the silkworm Bombyx mori.
    Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 1997
    Co-Authors: Shin'ichiro Satake, Hiroshi Kataoka, Makoto Masumura, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Akira Mizoguchi
    Abstract:

    The effects of an insect insulin-related peptide, Bombyxin, on carbohydrate metabolism were investigated in the silkworm Bombyx mori. Bombyxin lowered the concentration of the major hemolymph sugar, trehalose, in a dose-dependent manner when injected into neck-ligated larvae. Bombyxin also caused elevated trehalase activity in the midgut and muscle, suggesting that Bombyxin induces hypotrehalosemia by promoting the hydrolysis of hemolymph trehalose to glucose and thereby facilitating its transport into tissues. In addition, Bombyxin reduced the glycogen content in the fat body and concurrently raised the percentage of active glycogen phosphorylase in this tissue. Because hemolymph trehalose is also a major storage form of carbohydrate in insects, our results indicate that Bombyxin reduces the amount of both principal storage carbohydrates in B. mori larvae. It is therefore suggested that although Bombyxin is involved in the control of carbohydrate metabolism like insulin, the physiological role of Bombyxin in insects is different from that of insulin in mammals.

  • Multiple gene copies for Bombyxin, an insulin-related peptide of the silkmoth Bombyx mori: structural signs for gene rearrangement and duplication responsible for generation of multiple molecular forms of Bombyxin.
    Journal of molecular biology, 1996
    Co-Authors: Hidehiko Kondo, Hironori Ishizaki, Akinori Suzuki, Masaya Ino, Masafumi Iwami
    Abstract:

    Thirty-eight genes that encode Bombyxin, the insulin-related brain secretory peptide of the silkmothBombyx mori, have been cloned and characterized. These genes have been classified into four families, A, B, C and D, according to their sequence similarity. All the Bombyxin genes lack introns. Five of them have structural features of pseudogenes. The 38 genes cluster in the three DNA segments ofBombyxin unique distribution patterns. Their arrangement has been classified into three categories: gene pairs, gene triplets and single genes. In the pairs, two Bombyxin genes belonging to families B and A (B/A) or to families B and C (B/C) are apposed with opposite transcriptional orientation. All triplets are arranged in the order of the family-B, family-C and family-A genes, and the transcriptional directions of the family-C and family-A genes are opposite to the direction of the family-B gene. The Bombyxin gene triplets may have been generated by an unequal crossing-over between two gene pairs, B/A and B/C. Crossing-over may have occurred in the Bombyxin family-B genes to increase their structural diversity. Duplications may have served to multiply the Bombyxin gene triplets. These genomic rearrangements are thought to have led to the generation of multiple Bombyxin gene copies and their diversity in structure and genomic organization.

  • identification of the receptor recognition surface of Bombyxin ii an insulin like peptide of the silkmothbombyx mori critical importance of the b chain central part
    Journal of Molecular Biology, 1995
    Co-Authors: Hiroshi Kataoka, Akira Isogai, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Hiromichi Nagasawa, Hideki Hatanaka, Daisuke Kohda, Fuyuhikofn Inagaki
    Abstract:

    Abstract Bombyxin-II, a brain-secretory peptide of the silkmothBombyx mori, shares 40% sequence identity and the characteristics core structure with human insulin. In spite of the structural similarity, no cross-activity is observed between them. To localize the active region of Bombyxin-II, we have synthesized chimeric molecules of Bombyxin-II and human insulin, and examined their Bombyxin activity. Two chimeric molecules, which were sequentially identical except for the B-chain central part, showed significantly different potencies in Bombyxin activity. Solution structure determination of these chimeric molecules revealed that their B-chain central parts took similar main-chain conformation, but formed dissimilar patches on their molecular surfaces. Therefore, the surface patch formed by the central part of the Bombyxin-II B-chain is of critical importance for recognition of the Bombyxin receptor. The above results, together with other data on the structure-activity relationships of Bombyxin, indicate that the receptor-recognition surface of Bombyxin-II includes the A-chain N and C, termini in addition to the B-chain central part. Though Bombyxin-II, human insulin and human relaxin 2 use the common surface as their receptor-recognition sites, each of the surface patches is characterized by the variety of involved side-chains. Insulin and relaxin involve additional parts for receptor recognition, particularly the B-chain C-terminal part and the extended A-chain N-terminal helix, respectively. In conclusion, these ligands have evolved their own specific mechanisms for receptor recognition while retaining the major recognition surface.

Akinori Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • Bombyxin, an insulin-related peptide of insects, reduces the major storage carbohydrates in the silkworm Bombyx mori.
    Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 1997
    Co-Authors: Shin'ichiro Satake, Hiroshi Kataoka, Makoto Masumura, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Akira Mizoguchi
    Abstract:

    The effects of an insect insulin-related peptide, Bombyxin, on carbohydrate metabolism were investigated in the silkworm Bombyx mori. Bombyxin lowered the concentration of the major hemolymph sugar, trehalose, in a dose-dependent manner when injected into neck-ligated larvae. Bombyxin also caused elevated trehalase activity in the midgut and muscle, suggesting that Bombyxin induces hypotrehalosemia by promoting the hydrolysis of hemolymph trehalose to glucose and thereby facilitating its transport into tissues. In addition, Bombyxin reduced the glycogen content in the fat body and concurrently raised the percentage of active glycogen phosphorylase in this tissue. Because hemolymph trehalose is also a major storage form of carbohydrate in insects, our results indicate that Bombyxin reduces the amount of both principal storage carbohydrates in B. mori larvae. It is therefore suggested that although Bombyxin is involved in the control of carbohydrate metabolism like insulin, the physiological role of Bombyxin in insects is different from that of insulin in mammals.

  • Multiple gene copies for Bombyxin, an insulin-related peptide of the silkmoth Bombyx mori: structural signs for gene rearrangement and duplication responsible for generation of multiple molecular forms of Bombyxin.
    Journal of molecular biology, 1996
    Co-Authors: Hidehiko Kondo, Hironori Ishizaki, Akinori Suzuki, Masaya Ino, Masafumi Iwami
    Abstract:

    Thirty-eight genes that encode Bombyxin, the insulin-related brain secretory peptide of the silkmothBombyx mori, have been cloned and characterized. These genes have been classified into four families, A, B, C and D, according to their sequence similarity. All the Bombyxin genes lack introns. Five of them have structural features of pseudogenes. The 38 genes cluster in the three DNA segments ofBombyxin unique distribution patterns. Their arrangement has been classified into three categories: gene pairs, gene triplets and single genes. In the pairs, two Bombyxin genes belonging to families B and A (B/A) or to families B and C (B/C) are apposed with opposite transcriptional orientation. All triplets are arranged in the order of the family-B, family-C and family-A genes, and the transcriptional directions of the family-C and family-A genes are opposite to the direction of the family-B gene. The Bombyxin gene triplets may have been generated by an unequal crossing-over between two gene pairs, B/A and B/C. Crossing-over may have occurred in the Bombyxin family-B genes to increase their structural diversity. Duplications may have served to multiply the Bombyxin gene triplets. These genomic rearrangements are thought to have led to the generation of multiple Bombyxin gene copies and their diversity in structure and genomic organization.

  • development and secretory function of neurosecretory a cell in brain of bombyx mori
    Archives of Insect Biochemistry and Physiology, 1996
    Co-Authors: Hiromu Akai, Hiroshi Kataoka, Akinori Suzuki, Takayuki Nagashima, Shinji Aoyagi, Yasuhisa Endo, Makiko F Uwo, Kiyoshi Asaoka, Emiko Kobayashi
    Abstract:

    Histological and immunohistochemical observations showed that four pairs of neurosecretory A cells coincide with the Bombyxin neuron which produces the 4K-prothoracicotropic hormone (4K-PTTH). The A cells are characterized by a large cytoplasmic vacuole containing homogeneous granular materials, but the vacuole does not contain the Bombyxin. Bombyxin axons from the A cells are distributed on the surface of the corpus allatum (CA), and neurosecretory granules (NSGs) are released by exocytosis at earlier stages than those in other neurosecretory axons (NSAs). Embryonic Bombyxin neurons show characteristics of secretory function after the bristle formation stage (156 h after egg laying) and become the neurosecretory A cells in the larval stage. © 1996 Wiley-Liss, Inc.

  • identification of the receptor recognition surface of Bombyxin ii an insulin like peptide of the silkmothbombyx mori critical importance of the b chain central part
    Journal of Molecular Biology, 1995
    Co-Authors: Hiroshi Kataoka, Akira Isogai, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Hiromichi Nagasawa, Hideki Hatanaka, Daisuke Kohda, Fuyuhikofn Inagaki
    Abstract:

    Abstract Bombyxin-II, a brain-secretory peptide of the silkmothBombyx mori, shares 40% sequence identity and the characteristics core structure with human insulin. In spite of the structural similarity, no cross-activity is observed between them. To localize the active region of Bombyxin-II, we have synthesized chimeric molecules of Bombyxin-II and human insulin, and examined their Bombyxin activity. Two chimeric molecules, which were sequentially identical except for the B-chain central part, showed significantly different potencies in Bombyxin activity. Solution structure determination of these chimeric molecules revealed that their B-chain central parts took similar main-chain conformation, but formed dissimilar patches on their molecular surfaces. Therefore, the surface patch formed by the central part of the Bombyxin-II B-chain is of critical importance for recognition of the Bombyxin receptor. The above results, together with other data on the structure-activity relationships of Bombyxin, indicate that the receptor-recognition surface of Bombyxin-II includes the A-chain N and C, termini in addition to the B-chain central part. Though Bombyxin-II, human insulin and human relaxin 2 use the common surface as their receptor-recognition sites, each of the surface patches is characterized by the variety of involved side-chains. Insulin and relaxin involve additional parts for receptor recognition, particularly the B-chain C-terminal part and the extended A-chain N-terminal helix, respectively. In conclusion, these ligands have evolved their own specific mechanisms for receptor recognition while retaining the major recognition surface.

  • three dimensional solution structure of Bombyxin ii an insulin like peptide of the silkmothbombyx mori structural comparison with insulin and relaxin
    Journal of Molecular Biology, 1995
    Co-Authors: Koji Nagata, Hiroshi Kataoka, Akira Isogai, Hironori Ishizaki, Akinori Suzuki, Hiromichi Nagasawa, Hideki Hatanaka, Daisuke Kohda, Fuyuhiko Inagaki
    Abstract:

    Abstract The three-dimensional solution structure of Bombyxin-II, an insulin-like two-chain peptide produced by the brain of the silkwormBombyx morihas been determined by simulated annealing calculations based on 535 distance constraints and 24 torsion-angle constraints derived from NMR data and three distance constraints of the disulfide bonds. To our knowledge, this is the first three-dimensional structure determined for an invertebrate insulin-related peptide. The root-mean-square deviations between the best 10 structures and the mean structure are 0.58(±0.15) A for the backbone heavy atoms (N, CαC) and 1.03(±0.18) A for all non-hydrogen atoms if less well-defined N and C termini (A1, A20, B(−2) to B4 and B23 to B25) are excluded. The overall main-chain structure of Bombyxin-II is similar to that of insulin. However, there are significant conformational and functional differences in their B-chain C-terminal parts. The B-chain C-terminal part of Bombyxin-II adopts an extension of the B-chain central helix like that of relaxin and is not required for Bombyxin activity, while the corresponding part of insulin adopts a sharp turn and a β-strand and is essential for insulin activity. This structure demonstrates that Bombyxin-II is more closely related to relaxin than to insulin, and suggests that insulin might have evolved the additional receptor-recognition site in the B-chain C-terminal β-strand to distinguish itself from Bombyxin and relaxin. The structure of Bombyxin-II thus provides novel insights into the receptor recognition and divergent molecular evolution of insulin-super family peptides.

Masafumi Iwami - One of the best experts on this subject based on the ideXlab platform.

  • Refinement of ectopic protein expression through the GAL4/UAS system in Bombyx mori: application to behavioral and developmental studies
    Scientific Reports, 2017
    Co-Authors: Chiho Hara, Masafumi Iwami, Koudai Morishita, Seika Takayanagi-kiya, Akihisa Mikami, Keiro Uchino, Takeshi Sakurai, Ryohei Kanzaki, Hideki Sezutsu, Taketoshi Kiya
    Abstract:

    Silkmoth, Bombyx mori , is one of the important model insects in which transgenic techniques and the GAL4/UAS system are applicable. However, due to cytotoxicity and low transactivation activity of GAL4, effectiveness of the GAL4/UAS system and its application in B. mori are still limited. In the present study, we refined the previously reported UAS vector by exploiting transcriptional and translational enhancers, and achieved 200-fold enhancement of reporter GFP fluorescence in the GAL4/UAS system. Enhanced protein expression of membrane-targeted GFP and calcium indicator protein (GCaMP5G) drastically improved visualization of fine neurite structures and neural activity, respectively. Also, with the refined system, we generated a transgenic strain that expresses tetanus toxin light chain (TeTxLC), which blocks synaptic transmission, under the control of GAL4. Ectopic TeTxLC expression in the sex pheromone receptor neurons inhibited male courtship behavior, proving effectiveness of TeTxLC on loss-of-function analyses of neural circuits. In addition, suppression of prothoracicotropic hormone (PTTH) or insulin-like peptide (Bombyxin) secretion impaired developmental timing and growth rate, respectively. Furthermore, we revealed that larval growth is sex-differentially regulated by these peptide hormones. The present study provides important technical underpinnings of transgenic approaches in silkmoths and insights into mechanisms of postembryonic development in insects.

  • refinement of ectopic protein expression through the gal4 uas system in bombyx mori application to behavioral and developmental studies
    Scientific Reports, 2017
    Co-Authors: Chiho Hara, Masafumi Iwami, Koudai Morishita, Akihisa Mikami, Keiro Uchino, Takeshi Sakurai, Ryohei Kanzaki, Hideki Sezutsu, Seika Takayanagikiya, Taketoshi Kiya
    Abstract:

    Silkmoth, Bombyx mori, is one of the important model insects in which transgenic techniques and the GAL4/UAS system are applicable. However, due to cytotoxicity and low transactivation activity of GAL4, effectiveness of the GAL4/UAS system and its application in B. mori are still limited. In the present study, we refined the previously reported UAS vector by exploiting transcriptional and translational enhancers, and achieved 200-fold enhancement of reporter GFP fluorescence in the GAL4/UAS system. Enhanced protein expression of membrane-targeted GFP and calcium indicator protein (GCaMP5G) drastically improved visualization of fine neurite structures and neural activity, respectively. Also, with the refined system, we generated a transgenic strain that expresses tetanus toxin light chain (TeTxLC), which blocks synaptic transmission, under the control of GAL4. Ectopic TeTxLC expression in the sex pheromone receptor neurons inhibited male courtship behavior, proving effectiveness of TeTxLC on loss-of-function analyses of neural circuits. In addition, suppression of prothoracicotropic hormone (PTTH) or insulin-like peptide (Bombyxin) secretion impaired developmental timing and growth rate, respectively. Furthermore, we revealed that larval growth is sex-differentially regulated by these peptide hormones. The present study provides important technical underpinnings of transgenic approaches in silkmoths and insights into mechanisms of postembryonic development in insects.

  • identification of novel Bombyxin genes from the genome of the silkmoth bombyx mori and analysis of their expression
    Zoological Science, 2011
    Co-Authors: Abu F. M. Aslam, Taketoshi Kiya, Kazuei Mita, Masafumi Iwami
    Abstract:

    Insulin family peptide members play key roles in regulating growth, metabolism, and reproduction. Bombyxin is an insulin-related peptide of the silkmoth Bombyx mori. We analyzed the full genome of B. mori and identified five novel Bombyxin families, V to Z. We characterized the genomic organization and chromosomal location of the novel Bombyxin family genes. In contrast to previously identified Bombyxin genes, Bombyxin-V and -Z genes had intervening introns at almost the same positions as vertebrate insulin genes. We performed reverse transcription-polymerase chain reaction and in situ hybridization in different tissues and developmental stages to observe their temporal and spatial expression patterns. The newly identified Bombyxin genes were expressed in diverse tissues: Bombyxin-V, -W, and -Y mRNAs were expressed in the brain and Bombyxin-X mRNA in fat bodies. Bombyxin-Y gene was expressed in both brain and ovary of larval stages. High level of Bombyxin-Z gene expression in the follicular cells may suggest its function in reproduction. The presence of a short C-peptide domain and an extended A chain domain, and high expression of Bombyxin-X gene in the fat body cells during non-feeding stages suggest its insulin-like growth factor-like function. These results suggest that the Bombyxin genes originated from a common ancestral gene, similar to the vertebrate insulin gene, and evolved into a diverse gene family with multiple functions.

  • Identification of novel Bombyxin genes from the genome of the silkmoth Bombyx mori and analysis of their expression
    2011
    Co-Authors: Abu F. M. Aslam, Taketoshi Kiya, Kazuei Mita, Masafumi Iwami
    Abstract:

    Insulin family peptide members play key roles in regulating growth, metabolism, and reproduction. Bombyxin is an insulin-related peptide of the silkmoth Bombyx mori. We analyzed the full genome of B. mori and identified five novel Bombyxin families, V to Z. We characterized the genomic orga-nization and chromosomal location of the novel Bombyxin family genes. In contrast to previously identified Bombyxin genes, Bombyxin-V and-Z genes had intervening introns at almost the same positions as vertebrate insulin genes. We performed reverse transcription-polymerase chain reaction and in situ hybridization in different tissues and developmental stages to observe their temporal and spatial expression patterns. The newly identified Bombyxin genes were expressed in diverse tissues: Bombyxin-V,-W, and-Y mRNAs were expressed in the brain and Bombyxin-X mRNA in fat bodies. Bombyxin-Y gene was expressed in both brain and ovary of larval stages. High level of Bombyxin-Z gene expression in the follicular cells may suggest its function in reproduction. The presence of a short C-peptide domain and an extended A chain domain, and high expression o

  • Transcription Element Responsible for the Brain Cell-Specific Expression of the Bombyxin Gene that Encodes an Insect Insulin-related Peptide
    Zoological Science, 2001
    Co-Authors: Salah Eldin Abdel Salam, K. Moto, Sho Sakurai, Masafumi Iwami
    Abstract:

    Abstract Invertebrate insulin-related peptides play key roles in growth and metabolism. Genes encoding these peptides are specifically expressed in neurosecretory cells. Bombyxin genes of the silkmoth Bombyx mori encode insulin-related peptides and are expressed in four pairs of the neurosecretory cells in pars intercerebralis of brain. No regulatory element has been identified to confer the neurosecretory cell-specific expression of Bombyxin gene. By promoter-deletion analysis and in vitro electroporation, we identified a transcription element essential for the cell-specific expression of Bombyxin F1 gene, one of the Bombyxin multifamily genes. The element was localized in the region from −170 to −159 bp upstream of the translation start site of the F1 gene. We named the element as BOSE, Bombyxin gene-Specific Element. No protein that would bind to BOSE was found by searching the transcription factors database. In addition, an activator element responsible for increasing the expression level was identifi...

Koji Nagata - One of the best experts on this subject based on the ideXlab platform.

  • Bombyxin secretion in the adult silkmoth bombyx mori sex specificity and its correlation with metabolism
    Journal of Insect Physiology, 1999
    Co-Authors: Shin'ichiro Satake, Hiroshi Kataoka, Koji Nagata, Akira Mizoguchi
    Abstract:

    Changes in the hemolymph Bombyxin titer of the adult silkmoth Bombyx mori were investigated by time-resolved fluoroimmunoassay. Immediately after eclosion, hemolymph Bombyxin titers were low in both males and females, and then increased steeply in males to a very high level and this high titer was maintained for at least 3 h, whereas the titer increment in females was small and transient. The difference in the change of Bombyxin titer between males and females suggests that Bombyxin is responsible for the regulation of physiological changes underlying sexually different activities of the adult moths. However, no evidence was obtained that Bombyxin controls adult metabolism as far as the effects of Bombyxin on the concentrations of carbohydrates and lipids in the hemolymph were investigated. The change in the hemolymph trehalose concentration was almost the same between sexes, and between intact and neck-ligated moths. Furthermore, Bombyxin injection did not affect the hemolymph trehalose concentration nor trehalase activity in the muscle. Although the hemolymph lipid concentration rose after eclosion in males, it was not influenced by Bombyxin. These results exhibit striking contrast to the results of our previous study, in which Bombyxin showed hypotrehalosemic activity in the larval stage, thus indicating that the action of Bombyxin changes during metamorphosis.

  • three dimensional structure and receptor recognition sites of Bombyxin ii an insulin like brain secretory peptide of the silkmoth
    1999
    Co-Authors: Koji Nagata, Hiroshi Kataoka, Hironori Ishizaki, Minoru Tanaka, Hideki Hatanaka, Daisuke Kohda, K Momomura, K Tamori, Takashi Kadowaki, H. Nagasawa
    Abstract:

    K. NAGATA1,2 , H. HATANAKA1 , D. KOHDA1 , H. ISHIZAKI3 , K. MOMOMURA4 , K. TAMORI4 , T. KADOWAKI4 , M. TANAKA2 , H. KATAOKA2 , H. NAGASAWA2 , A. ISOGAI2 , A. SUZUKI2 and F. INAGAKI1 1 Department of Molecular Physiology, The Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan 2 Department of Agricultural Chemistry, The University of Tokyo, Tokyo, Japan 3 Department of Biology, Nagoya University, Nagoya, Japan 4 The Third Department of Internal Medicine, The University of Tokyo, Tokyo, Japan

  • Bombyxin, an insulin-related peptide of insects, reduces the major storage carbohydrates in the silkworm Bombyx mori.
    Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 1997
    Co-Authors: Shin'ichiro Satake, Hiroshi Kataoka, Makoto Masumura, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Akira Mizoguchi
    Abstract:

    The effects of an insect insulin-related peptide, Bombyxin, on carbohydrate metabolism were investigated in the silkworm Bombyx mori. Bombyxin lowered the concentration of the major hemolymph sugar, trehalose, in a dose-dependent manner when injected into neck-ligated larvae. Bombyxin also caused elevated trehalase activity in the midgut and muscle, suggesting that Bombyxin induces hypotrehalosemia by promoting the hydrolysis of hemolymph trehalose to glucose and thereby facilitating its transport into tissues. In addition, Bombyxin reduced the glycogen content in the fat body and concurrently raised the percentage of active glycogen phosphorylase in this tissue. Because hemolymph trehalose is also a major storage form of carbohydrate in insects, our results indicate that Bombyxin reduces the amount of both principal storage carbohydrates in B. mori larvae. It is therefore suggested that although Bombyxin is involved in the control of carbohydrate metabolism like insulin, the physiological role of Bombyxin in insects is different from that of insulin in mammals.

  • identification of the receptor recognition surface of Bombyxin ii an insulin like peptide of the silkmothbombyx mori critical importance of the b chain central part
    Journal of Molecular Biology, 1995
    Co-Authors: Hiroshi Kataoka, Akira Isogai, Hironori Ishizaki, Koji Nagata, Akinori Suzuki, Hiromichi Nagasawa, Hideki Hatanaka, Daisuke Kohda, Fuyuhikofn Inagaki
    Abstract:

    Abstract Bombyxin-II, a brain-secretory peptide of the silkmothBombyx mori, shares 40% sequence identity and the characteristics core structure with human insulin. In spite of the structural similarity, no cross-activity is observed between them. To localize the active region of Bombyxin-II, we have synthesized chimeric molecules of Bombyxin-II and human insulin, and examined their Bombyxin activity. Two chimeric molecules, which were sequentially identical except for the B-chain central part, showed significantly different potencies in Bombyxin activity. Solution structure determination of these chimeric molecules revealed that their B-chain central parts took similar main-chain conformation, but formed dissimilar patches on their molecular surfaces. Therefore, the surface patch formed by the central part of the Bombyxin-II B-chain is of critical importance for recognition of the Bombyxin receptor. The above results, together with other data on the structure-activity relationships of Bombyxin, indicate that the receptor-recognition surface of Bombyxin-II includes the A-chain N and C, termini in addition to the B-chain central part. Though Bombyxin-II, human insulin and human relaxin 2 use the common surface as their receptor-recognition sites, each of the surface patches is characterized by the variety of involved side-chains. Insulin and relaxin involve additional parts for receptor recognition, particularly the B-chain C-terminal part and the extended A-chain N-terminal helix, respectively. In conclusion, these ligands have evolved their own specific mechanisms for receptor recognition while retaining the major recognition surface.

  • three dimensional solution structure of Bombyxin ii an insulin like peptide of the silkmothbombyx mori structural comparison with insulin and relaxin
    Journal of Molecular Biology, 1995
    Co-Authors: Koji Nagata, Hiroshi Kataoka, Akira Isogai, Hironori Ishizaki, Akinori Suzuki, Hiromichi Nagasawa, Hideki Hatanaka, Daisuke Kohda, Fuyuhiko Inagaki
    Abstract:

    Abstract The three-dimensional solution structure of Bombyxin-II, an insulin-like two-chain peptide produced by the brain of the silkwormBombyx morihas been determined by simulated annealing calculations based on 535 distance constraints and 24 torsion-angle constraints derived from NMR data and three distance constraints of the disulfide bonds. To our knowledge, this is the first three-dimensional structure determined for an invertebrate insulin-related peptide. The root-mean-square deviations between the best 10 structures and the mean structure are 0.58(±0.15) A for the backbone heavy atoms (N, CαC) and 1.03(±0.18) A for all non-hydrogen atoms if less well-defined N and C termini (A1, A20, B(−2) to B4 and B23 to B25) are excluded. The overall main-chain structure of Bombyxin-II is similar to that of insulin. However, there are significant conformational and functional differences in their B-chain C-terminal parts. The B-chain C-terminal part of Bombyxin-II adopts an extension of the B-chain central helix like that of relaxin and is not required for Bombyxin activity, while the corresponding part of insulin adopts a sharp turn and a β-strand and is essential for insulin activity. This structure demonstrates that Bombyxin-II is more closely related to relaxin than to insulin, and suggests that insulin might have evolved the additional receptor-recognition site in the B-chain C-terminal β-strand to distinguish itself from Bombyxin and relaxin. The structure of Bombyxin-II thus provides novel insights into the receptor recognition and divergent molecular evolution of insulin-super family peptides.

Akira Mizoguchi - One of the best experts on this subject based on the ideXlab platform.

  • Bombyxin bombyx insulin like peptide increases the respiration rate through facilitation of carbohydrate catabolism in bombyx mori
    Frontiers in Endocrinology, 2019
    Co-Authors: Yuko Kawabe, Hannah Waterson, Akira Mizoguchi
    Abstract:

    : Bombyxin-II, an insulin-like peptide of the silkmoth Bombyx mori, has been shown to reduce both the trehalose concentration in the hemolymph and the glycogen content in some tissues of B. mori larvae. However, little is known about how these storage carbohydrates are utilized. To address this question, the effects of Bombyxin-II injection into Bombyx larvae on the tissue lipid level, respiration rate, and glycolytic activity of tissues were investigated. Bombyxin-II did not affect lipid accumulation in the hemolymph and fat body, while it increased the rate of oxygen consumption and increased the content of fructose 2, 6-bisphosphate, a potent activator of glycolysis, in the gonads, imaginal discs, and midgut. These results suggest that Bombyxin facilitates cellular energy production thereby supporting the tissue growth of insects.

  • insulin like and igf like peptides in the silkmoth bombyx mori discovery structure secretion and function
    Frontiers in Physiology, 2013
    Co-Authors: Akira Mizoguchi, Naoki Okamoto
    Abstract:

    A quarter of a century has passed since Bombyxin, the first insulin-like peptide identified in insects, was discovered in the silkmoth Bombyx mori. During these years, Bombyxin has been studied for its structure, genes, distribution, hemolymph titers, secretion control, as well as physiological functions, thereby stimulating a wide range of studies on insulin-like peptides in other insects. Moreover, recent studies have identified a new class of insulin family peptides, IGF-like peptides, in B. mori and Drosophila melanogaster, broadening the base of the research area of the insulin-related peptides in insects. In this review, we describe the achievements of the studies on insulin-like and IGF-like peptides mainly in B. mori with short histories of their discovery. Our emphasis is that Bombyxins, secreted by the brain neurosecretory cells, regulate nutrient-dependent growth and metabolism, whereas the IGF-like peptides, secreted by the fat body and other peripheral tissues, regulate stage-dependent growth of tissues.

  • relationship between firing activity of Bombyxin producing neurosecretory cells and hemolymph Bombyxin titer in the silkworm bombyx mori
    General and Comparative Endocrinology, 2004
    Co-Authors: Akiko Suenobu, Akira Mizoguchi, Toshio Ichikawa
    Abstract:

    Isolated brain-retrocerebral neurohemal complex of the silkworm of Bombyx mori was stimulated electrically and the released Bombyxin (an insulin-like neuropeptide) was measured using time-resolved fluoroimmunoassay. The amount of Bombyxin release depended on the number of stimulus pulses delivered to the axonal tract of the Bombyxin-producing (BP) neurosecretory cells, and 17 fg of Bombyxin per pulse was released from a cell. The titer of Bombyxin in the hemolymph of Bombyxin-II injected pupae decreased exponentially, the half-life being 170 min. To relate firing activity of a population of BP cells to the hormone titer in the hemolymph, Bombyxin titer and its change in the hemolymph were calculated numerically. We assumed that the amount of Bombyxin release was proportional to the firing rate of BP cells and the released Bombyxin was inactivated with the same time course of injected Bombyxin. Our calculations suggested that the hemolymph Bombyxin titer may fluctuate dynamically and the mean titer is 380 pg/ml, a level which is close to the actually determined Bombyxin titer at middle stages of pupal-adult development.

  • Glucose stimulates the release of Bombyxin, an insulin-related peptide of the silkworm Bombyx mori.
    General and comparative endocrinology, 2000
    Co-Authors: Makoto Masumura, Shin'ichiro Satake, Hironao Saegusa, Akira Mizoguchi
    Abstract:

    Abstract The effects of starvation and feeding on the release of Bombyxin, a peptide of insulin superfamily in insects, from the larval brain of the silkworm Bombyx mori were investigated. Following starvation, the Bombyxin titer in the hemolymph of larvae decreased, whereas its content in the brain increased. On the other hand, refeeding of the starved larvae resulted in an increase in the hemolymph Bombyxin titer and a rapid decrease in the hormone level in the brain. These results indicate that the release of Bombyxin from the brain is suppressed by starvation and stimulated by feeding. The hemolymph glucose titer also changed sharply upon starvation and refeeding, and a close relationship was observed between the changes in glucose concentrations and Bombyxin titers in the hemolymph. The injection of glucose into starved larvae could mimic the effect of refeeding on the release of Bombyxin, suggesting that glucose serves as the signal for the “fed” state of the animal. It is likely that glucose is a common nutritional signal for inducing the release of mammalian and insect insulins.

  • Bombyxin secretion in the adult silkmoth bombyx mori sex specificity and its correlation with metabolism
    Journal of Insect Physiology, 1999
    Co-Authors: Shin'ichiro Satake, Hiroshi Kataoka, Koji Nagata, Akira Mizoguchi
    Abstract:

    Changes in the hemolymph Bombyxin titer of the adult silkmoth Bombyx mori were investigated by time-resolved fluoroimmunoassay. Immediately after eclosion, hemolymph Bombyxin titers were low in both males and females, and then increased steeply in males to a very high level and this high titer was maintained for at least 3 h, whereas the titer increment in females was small and transient. The difference in the change of Bombyxin titer between males and females suggests that Bombyxin is responsible for the regulation of physiological changes underlying sexually different activities of the adult moths. However, no evidence was obtained that Bombyxin controls adult metabolism as far as the effects of Bombyxin on the concentrations of carbohydrates and lipids in the hemolymph were investigated. The change in the hemolymph trehalose concentration was almost the same between sexes, and between intact and neck-ligated moths. Furthermore, Bombyxin injection did not affect the hemolymph trehalose concentration nor trehalase activity in the muscle. Although the hemolymph lipid concentration rose after eclosion in males, it was not influenced by Bombyxin. These results exhibit striking contrast to the results of our previous study, in which Bombyxin showed hypotrehalosemic activity in the larval stage, thus indicating that the action of Bombyxin changes during metamorphosis.