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David A. Schooley - One of the best experts on this subject based on the ideXlab platform.

  • expression processing and secretion of a proteolytically sensitive Insect Diuretic Hormone by saccharomyces cerevisiae requires the use of a yeast strain lacking genes encoding the yap3 and mkc7 endoproteases found in the secretory pathway
    Biochemical Journal, 1998
    Co-Authors: Kathrin S Copley, David A. Schooley, William E Courchesne
    Abstract:

    A system is described for the heterologous expression of peptides in Saccharomyces cerevisiae. A synthetic gene encoding a precursor of the 41 amino acid Manduca sexta Diuretic Hormone (Mas-DH) was expressed at 0.8 mg/l purified peptide. A precursor of a mutant peptide of Mas-DH, Mas-DH[K22Q] was also expressed. The peptides were purified, then treated with peptidylglycine alpha-amidating enzyme to generate the alpha-amidated, mature, form of Mas-DH or Mas-DH[K22Q], which were biologically active. Successful expression of full-length Mas-DH+Gly depended upon the use of a protease-deficient yeast strain. In wild-type strains, Mas-DH+Gly was recovered only as proteolytic fragments, even in the presence of various protease inhibitors. Expression of Mas-DH+Gly in strains deficient in either the Mkc7 or the Yap3 protease reduced proteolysis, while no proteolysis of Mas-DH+Gly was detectable in a strain lacking both proteases. This protease-deficient strain may prove of general utility for expression of peptides. Analysis of recovered proteolytic fragments revealed a complex pattern of cleavage sites. Both the Yap3 and Mkc7 proteases preferred to cleave at a single Glu-Lys downward arrow-Glu-Arg site. Analysis of secondary cleavage sites showed that Yap3 preferred to cleave after either Lys or Arg and Mkc7 after Lys. This paper is the first report on the in vivo activity and specificity of Yap3 and Mkc7 expressed at physiological levels.

  • metabolism of an Insect Diuretic Hormone by malpighian tubules studied by liquid chromatography coupled with electrospray ionization mass spectrometry
    Proceedings of the National Academy of Sciences of the United States of America, 1997
    Co-Authors: Hong Li, Houle Wang, Kathleen M Schegg, David A. Schooley
    Abstract:

    The larger of two Diuretic Hormones of the tobacco hornworm, Manduca sexta, (Mas-DH) is a peptide of 41 residues. It is one of a family of seven currently known Insect Diuretic Hormones that are similar to the corticotropin-releasing factor–urotensin–sauvagine family of peptides. We investigated the possible inactivation of Mas-DH by incubating it in vitro with larval Malpighian tubules (Mt), the target organ of the Hormone. The medium was analyzed, and degradation products were identified, using on-line microbore reversed-phase liquid chromatography coupled to electrospray ionization mass spectrometry (RPLC-ESI-MS). This sensitive technique allows identification of metabolites of Mas-DH (present at an initial level of ≈1 μM). An accurate Mr value for a metabolite is usually sufficient for unambiguous identification. Mas-DH is cleaved by Mt proteases initially at L29–R30 and R30–A31 under our assay conditions; some Mas-DH is also oxidized, apparently at M2 and M11. The proteolysis can be inhibited by 5 mM EDTA, suggesting that divalent metals are needed for peptide cleavage. The oxidation of the Hormone can be inhibited by catalase or 1 mM methionine, indicating that H2O2 or related reactive oxygen species are responsible for the oxidative degradation observed. RPLC-ESI-MS is shown here to be an elegant and efficient method for studying peptide Hormone metabolism resulting from unknown proteases and pathways.

Jonathan P. Bacon - One of the best experts on this subject based on the ideXlab platform.

  • A comparison of the effects of two putative Diuretic Hormones from Locusta migratoria on isolated locust malpighian tubules.
    The Journal of Experimental Biology, 1993
    Co-Authors: Geoffrey M Coast, Richard C. Rayne, Timothy K. Hayes, A. I. Mallet, K. S. J. Thompson, Jonathan P. Bacon
    Abstract:

    Previous work has shown that a peptide related to arginine vasopressin is present in the suboesophageal ganglion of the locust, Locusta migratoria. This peptide was determined to be an anti-parallel dimer of the nonapeptide Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-Gly-NH2 and was reported to stimulate cyclic AMP production and fluid secretion in a combined Malpighian tubules and midgut preparation from locusts. For these reasons the peptide has been called the arginine-vasopressin-like Insect Diuretic Hormone (AVP-like IDH). Recently, a second Diuretic peptide (Locusta-DP), which is related to corticotropin releasing factor, has been identified: this is a potent stimulant of fluid secretion and cyclic AMP production by isolated locust tubules. Because water balance in Insects is likely to be controlled by a cocktail of Hormones acting on both Malpighian tubules and hindgut, this study directly compares the activity of these two peptides in fluid secretion and cyclic AMP production bioassays on one target organ, the isolated Malpighian tubule of Locusta migratoria. Locusta-DP was synthesised directly, whereas the dimeric AVP-like IDH was obtained by oxidation of a synthetic nonapeptide monomer. Products were separated by RP-HPLC and their structures unequivocally confirmed by enzymatic digestion, sequence analysis and electrospray mass spectrometry. We show that Locusta-DP causes strong stimulation of fluid secretion and cyclic AMP production, whereas the AVP-like IDH has no effect in either assay. These findings are discussed in the light of recent work on the anatomy and physiology of the vasopressin-like immunoreactive (VPLI) neurones in the suboesophageal ganglion of Locusta migratoria, the proposed source of the AVP-like peptide.

  • Key words: locust, diuresis, Diuretic peptide, Malpighian tubule, Locusta migratoria. A COMPARISON OF THE EFFECTS OF TWO PUTATIVE Diuretic HormoneS FROM LOCUSTA MIGRATORIA ON ISOLATED LOCUST MALPIGHIAN TUBULES
    1992
    Co-Authors: Geoffrey M Coast, Richard C. Rayne, Timothy K. Hayes, A. I. Mallet, K. S. J. Thompson, Jonathan P. Bacon
    Abstract:

    Previous work has shown that a peptide related to arginine vasopressin is present in the suboesophageal ganglion of the locust, Locusta migratoria. This peptide was determined to be an anti-parallel dimer of the nonapeptide Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-Gly-NH2 and was reported to stimulate cyclic AMP production and fluid secretion in a combined Malpighian tubules and midgut preparation from locusts. For these reasons the peptide has been called the arginine-vasopressin-like Insect Diuretic Hormone (AVP-like IDH). Recently, a second Diuretic peptide (Locusta-DP), which is related to corticotropin releasing factor, has been identified: this is a potent stimulant of fluid secretion and cyclic AMP production by isolated locust tubules. Because water balance in Insects is likely to be controlled by a cocktail of Hormones acting on both Malpighian tubules and hindgut, this study directly compares the activity of these two peptides in fluid secretion and cyclic AMP production bioassays on one target organ, the isolated Malpighian tubule of Locusta migratoria.Locusta-DP was synthesised directly, whereas the dimeric AVP-like IDH was obtained by oxidation of a synthetic nonapeptide monomer. Products were separated by RP-HPLC and their structures unequivocally confirmed by enzymati

Jacques Proux - One of the best experts on this subject based on the ideXlab platform.

  • Development of an enzyme immunoassay for arginine-vasopressin (AVP)-like Insect Diuretic Hormone
    Comparative Biochemistry and Physiology B, 1993
    Co-Authors: Jacques Proux, Amina Baskali, Christian Rémy, Christophe Creminon, Philippe Pradelles
    Abstract:

    Abstract 1. 1. The AVP-like Insect Diuretic Hormone is a biologically active antiparallel dimer present, along with its non-active monomeric form (Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-GlyNH2), in the African locust. 2. 2. It exhibits Diuretic activity by increasing fluid excretion at the level of the Malpighian tubules. 3. 3. To date, both monomer and dimer have been assayed using a radioimmunoassay originally prepared for mammalian AVP. 4. 4. We have developed here an original enzyme immunoassay based on the use of antibodies to Insect AVP-like raised in rabbits against synthetic monomers and dimers, using acetylcholinesterase conjugate as an enzymatic tracer. 5. 5. This enzyme immunoassay enables measurement of the dimer to be made with adequate sensitivity (0.3 nmol/l, i.e. 21 pg/well) and reproducibility while sensitivity of the monomer is somewhat lower (14 nmol/l, i.e. 480 pg/well). 6. 6. The assay was validated by assaying native dimer and monomer throughout the different steps of purification (from a crude extract to reversed-phase liquid chromatographic fractions). 7. 7. A good correlation was observed between radioimmunoassays and enzyme immunoassays. 8. 8. The enzyme immunoassay was also used to measure the level of AVP-like peptides in several Insect tissues not explored to date.

  • Deltamethrin-induced deregulation of the water balance in the migratory locust, Locusta migratoria
    Comparative Biochemistry and Physiology Part C: Pharmacology Toxicology and Endocrinology, 1993
    Co-Authors: Jacques Proux, Abdelilah Alaoui, Brigitte Moreteau, Amina Baskali
    Abstract:

    Abstract 1. Several Insecticides were tested for their ability to induce a water deregulation in the larval migratory locust. All of them provoked an accelerated dehydration (when compared to sham-operated Insects). Deltamethrin and baygon were the most potent. 2. This enhanced dehydration due to deltamethrin in adult locust resulted from an increase in the water loss through the feces. This increase was not due to a direct effect of deltamethrin on urine production by the Malpighian tubules but to a hormonal deregulation. 3. Intoxicated Insects produced large amounts of the vasopressin-like Insect Diuretic Hormone. This higher synthesis activity occurs within the hours following the Insecticide injection and is accompanied by an increase in water loss. 4. These hormonal and metabolic modifications are transient. Hormonal level and diuresis rate both return to the basal levels 7 hr after the Insecticide injection.

  • Rapid chromatographic separation of the AVP-like locust peptides from synthetic and biological mixtures. Quest for these peptides in some Insect, batrachian and mammalian nervous systems
    Insect Biochemistry and Molecular Biology, 1992
    Co-Authors: Jacques Proux, Philippe Beydon
    Abstract:

    Abstract The AVP-like Insect Diuretic Hormone, an antiparallel dimer and its monomeric form are present together in the locust ventral nerve cord. Classical reversed-phase liquid chromatographic procedures were developed to rapidly separate dimer and monomer from their synthetic and native mixtures. These procedures were then used to look for AVP-like peptides in cockroach, stick-Insect, bumble-bee, frog and rat nervous tissues. Cockroach corpora cardiaca as well as a stick-Insect and bumble-bee ventral nerve cords contain AVP-like peptides whose chromatographic properties are similar to those of the locust AVP-like peptides.

  • Lack of responsiveness of Malpighian tubules to the AVP-like Insect Diuretic Hormone on migratory locusts infected with the protozoan Malameba locustae
    Journal of Invertebrate Pathology, 1991
    Co-Authors: Jacques Proux
    Abstract:

    Abstract In 1989–1990, our colony of Locusta migratoria was seriously infected by a protozoan Malameba locustae . This infection was then rooted out thanks to an appropriate sulfamide treatment. Since this parasite is known to infest chiefly Malpighian tubules, we studied the ability of these organs to respond to their main regulatory factor: the arginine-vasopressin-like Insect Diuretic Hormone (AVP-like IDH). Results demonstrated that the ability of infected Malpighian tubules to respond to the hormonal stimulus is dramatically decreased, likely because of damage at the receptor level. The rest of the tissue is less affected and it remains able to play its excretory role as soon as the cellular working is directly stimulated (when using second messengers for example). The ability of the infected locusts to synthesize AVP-like IDH is not affected either since noninfected locusts are stimulated with hormonal extracts of infected animals. This insensitiveness of the infected locusts to their own Diuretic Hormone is transient and stops when the infection is over.

David A Lovejoy - One of the best experts on this subject based on the ideXlab platform.

  • Identification of members of the gonadotropin-releasing Hormone (GnRH), corticotropin-releasing factor (CRF) families in the genome of the holocephalan, Callorhinchus milii (elephant shark).
    General and comparative endocrinology, 2011
    Co-Authors: Tanya G. Nock, Dhan Chand, David A Lovejoy
    Abstract:

    The gonadotropin-releasing Hormone (GnRH) and corticotropin-releasing family (CRF) are two neuropeptides families that are strongly conserved throughout evolution. Recently, the genome of the holocephalan, Callorhinchus milii (elephant shark) has been sequenced. The phylogenetic position of C. milii, along with the relatively slow evolution of the cartilaginous fish suggests that neuropeptides in this species may resemble the earliest gnathostome forms. The genome of the elephant shark was screened, in silico, using the various conserved motifs of both the vertebrate CRF paralogs and the Insect Diuretic Hormone sequences to identify the structure of the C. milii CRF/DH-like peptides. A similar approach was taken to identify the GnRH peptides using conserved motifs in both vertebrate and invertebrate forms. Two CRF peptides, a urotensin-1 peptide and a urocortin 3 peptide were found in the genome. There was only about 50% sequence identity between the two CRF peptides suggesting an early divergence. In addition, the urocortin 2 peptide seems to have been lost and was identified as a pseudogene in C. milii. In contrast to the number of CRF family peptides, only a GnRH-II preproHormone with the conserved mature decapeptide was found. This confirms early studies about the identity of GnRH in the Holocephali, and suggests that the Holocephali and Elasmobranchii differ with respect to GnRH structure and function.

  • characterization of a corticotropin releasing factor crf Diuretic Hormone like peptide from tunicates insight into the origins of the vertebrate crf family
    General and Comparative Endocrinology, 2010
    Co-Authors: David A Lovejoy, Dalia Barsytelovejoy
    Abstract:

    Abstract The corticotropin-releasing factor (CRF) superfamily of peptides includes the four paralogous vertebrate peptide lineages of CRF, urotensin-1/urocortin/sauvagine, urocortin 2 and urocortin 3, as well as the Diuretic Hormones (DH) and peptides of the arthropods. However, there are considerable sequence differences between the group of vertebrate peptides and those of the arthropods, notably Insects. Because of the likely incidence of the formation of paralogous forms within the Insects and the great variation in primary structures among these peptides, establishing the structure of the ancestral vertebrate version has not been possible. We screened the genomes of the tunicates, Ciona intestinalis and Ciona savignii , in silico , using the various conserved motifs of both the vertebrate CRF paralogues and the Insect Diuretic Hormone sequences to identify the structure of the Ciona CRF/DH-like peptide genes. A single peptide gene was found in both genomes that possessed motifs reflective of both groups of peptides. These structures suggest a single CRF-like peptide was inherited by vertebrates and possibly chordates. Moreover, the conserved structure of the CRF peptide may have become constrained once it became associated with the regulation of the hypothalamus–pituitary–adrenal/interrenal axis.

Jeff D. Reagan - One of the best experts on this subject based on the ideXlab platform.

  • expression cloning of an Insect Diuretic Hormone receptor a member of the calcitonin secretin receptor family
    Journal of Biological Chemistry, 1994
    Co-Authors: Jeff D. Reagan
    Abstract:

    Abstract Insect Diuretic Hormones and their receptors regulate fluid and ion secretion and thus are attractive targets for the design of novel Insect control agents. A complementary DNA clone encoding a corticotropin-releasing factor-related Diuretic Hormone receptor from the tobacco hornworm Manduca sexta was isolated by expression cloning in COS-7 cells. The receptor consists of 395 amino acids and contains seven putative transmembrane domains. The expressed receptor binds M. sexta Diuretic Hormone, as well as several related Insect Diuretic peptides with high affinity. Furthermore, each of these peptides stimulate adenylate cyclase in COS-7 cells transfected with the receptor. The M. sexta Diuretic Hormone receptor is homologous to the receptors for calcitonin, secretin, vasoactive intestinal peptide, parathyroid Hormone, glucagon-like peptide 1, growth Hormone-releasing Hormone, pituitary adenylate cyclase-activating polypeptide, and glucagon. The M. sexta Diuretic Hormone receptor is the first nonmammalian member of this family to be identified.

  • Expression cloning of an Insect Diuretic Hormone receptor. A member of the calcitonin/secretin receptor family.
    Journal of Biological Chemistry, 1994
    Co-Authors: Jeff D. Reagan
    Abstract:

    Abstract Insect Diuretic Hormones and their receptors regulate fluid and ion secretion and thus are attractive targets for the design of novel Insect control agents. A complementary DNA clone encoding a corticotropin-releasing factor-related Diuretic Hormone receptor from the tobacco hornworm Manduca sexta was isolated by expression cloning in COS-7 cells. The receptor consists of 395 amino acids and contains seven putative transmembrane domains. The expressed receptor binds M. sexta Diuretic Hormone, as well as several related Insect Diuretic peptides with high affinity. Furthermore, each of these peptides stimulate adenylate cyclase in COS-7 cells transfected with the receptor. The M. sexta Diuretic Hormone receptor is homologous to the receptors for calcitonin, secretin, vasoactive intestinal peptide, parathyroid Hormone, glucagon-like peptide 1, growth Hormone-releasing Hormone, pituitary adenylate cyclase-activating polypeptide, and glucagon. The M. sexta Diuretic Hormone receptor is the first nonmammalian member of this family to be identified.