N-terminal amino acid sequence of an insect neurohormone, melanization and reddish coloration hormone (MRCH): heterogeneity and sequence homology with human insulin-like growth factor II

The evolution of insulin glargine and its continuing contribution to diabetes care

The epoch-making discovery of insulin heralded a new dawn in the management of diabetes. However, the earliest, unmodified soluble insulin preparations were limited by their short duration of action, necessitating multiple daily injections. Initial attempts to protract the duration of action of insulin involved the use of various additives, including vasoconstrictor substances, which met with limited success. The subsequent elucidation of the chemical and three-dimensional structure of insulin and its chemical synthesis and biosynthesis allowed modification of the insulin molecule itself, resulting in insulin analogs that are designed to mimic normal endogenous insulin secretion during both fasting and prandial conditions. Insulin glargine was the first once-daily, long-acting insulin analog to be introduced into clinical practice more than 10 years ago and is specifically designed to provide basal insulin requirements. It has a prolonged duration of action and no distinct insulin peak, making it suitable for once-daily administration and reducing the risk of nocturnal hypoglycemia that is seen with intermediate-acting insulins. Insulin glargine can be used in combination with prandial insulin preparations and non-insulin anti-diabetic agents according to individual requirements.

Small is beautiful: insulin-like growth factors and their role in growth, development, and cancer

Insulin-like growth factors were discovered more than 50 years ago as mediators of growth hormone that effect growth and differentiation of bone and skeletal muscle. Interest of the role of insulin-like growth factors in cancer reached a peak in the 1990s, and then waned until the availability in the past 5 years of monoclonal antibodies and small molecules that block the insulin-like growth factor 1 receptor. In this article, we review the history of insulin-like growth factors and their role in growth, development, organism survival, and in cancer, both epithelial cancers and sarcomas. Recent developments regarding phase I to II clinical trials of such agents are discussed, as well as potential studies to consider in the future, given the lack of efficacy of one such monoclonal antibody in combination with cytotoxic chemotherapy in a first-line study in metastatic non-small-cell lung adenocarcinoma. Greater success with these agents clinically is expected when combining the agents with inhibitors of other cell signaling pathways in which cross-resistance has been observed.

Identification of soluble binding proteins for an insect neuropeptide

A photoaffinity analog of Helicoverpa zea pheromone biosynthesis activating neuropeptide (Hez-PBAN) was used to identify PBAN binding proteins in various tissues of the corn earworm moth, H. zea. Synthetic Hez-PBAN was derivatized on Lys-27 with p-benzoyldihydrocinnamoyl-N-hydroxysuccinimide ester (BZDC-NHS ester). The resulting BZDC-PBAN stimulated pheromone production in H. zea isolated abdomens at levels comparable to those of the unmodified peptide. Photoaffinity labeling experiments using [3H]BZDC-PBAN with female moth tissues revealed soluble 100 and 115 kDa proteins in the brain-subesophageal ganglia complex, ventral nerve cord, and thoracic muscle that were specifically labeled with the PBAN analog.

Precursor polyprotein for multiple neuropeptides secreted from the suboesophageal ganglion of the silkworm Bombyx mori: characterization of the cDNA encoding the diapause hormone precursor and identification of additional peptides

Peptidergic neurons, which serve as source of various endocrine neuropeptides, were identified in the suboesophageal ganglion (SG) and brain of insects. In the silkworm Bombyx mori, SG is known to secrete two neuropeptides, diapause hormone (DH) responsible for induction of embryonic diapause and pheromone biosynthesis-activating neuropeptide, which share a pentapeptide amide, Phe-Xaa-Pro-Arg-Leu-NH2 (Xaa = Gly or Ser), at the C terminus. We have isolated cDNA clones for DH from the cDNA library of SG by using oligonucleotide probes. The molecular characterization of the cDNA reveals that the mRNA encodes an open reading frame consisting of 192 aa residues in which the 24-aa DH peptide is localized at the N-terminal region just after the signal peptide. A homology search proposed that the cDNA encodes pheromone biosynthesis-activating neuropeptide and three other neuropeptides [alpha-, beta-, and gamma-SG neuropeptide (SGNP)] in the region following DH, all of which are flanked by possible tryptic cleavage sites and share the Phe-Xaa-Pro-Arg-Leu-Gly sequence at the C terminus. Northern hybridization analysis clearly showed that the gene expression was limited to SG. We chemically synthesized alpha-, beta-, and gamma-SGNP and used them to identify components in extracts of SG and to examine biological functions, alpha- and gamma-SGNP were identified in extracts of SG, and the synthetic beta- and gamma-SGNP expressed weak DH activity. These results indicate that DH, along with four other neuropeptides, is generated from a common precursor polyprotein that is encoded by a single mRNA transcribed in neurosecretory cells of SG.

Neuropeptides of the silkworm, Bombyx mori

Six neuropeptides of the silkworm, Bombyx mori, have been isolated and chemically characterized during the past 10 years. They are bombyxin, prothoracicotropic hormone, pheromone-biosynthesis-activating neuropeptide/melanization-and-reddish-coloration hormone, diapause hormone, eclosion hormone, and adipokinetic hormone. Recent progress in research on these neuropeptides is described.

Homologies between the amino acid sequences of some vertebrate peptide hormones and peptides isolated from invertebrate sources

1. The 4K-prothoracicotropic hormone (PTTH) or bombyxin and the melanization-reddish coloration hormone of the silkworm Bombyx mori resemble insulin and insulin-like growth factors. 2. The family of adipokinetic/red pigment concentrating hormones has some similarity with glucagon. 3. Members of the FMRFamide family are found in vertebrates as well as in invertebrates. 4. In Locusta, a molecule immunologically and biologically related to amphibian melanophore stimulating hormone has been partially characterized. 5. Enkephalins and enkephalin-related peptides occur in insects and other invertebrates. 6. Peptides belonging to the tachykinin family have been isolated from molluscan (Octopus) salivary glands and from insect nervous tissue (Locusta migratoria). 7. Invertebrate arginine-vasotocin homologs have been isolated from an insect (Locusta migratoria) and from a mollusc (Conus). 8. In Leucophaea, Locusta and Drosophila, peptides resembling those of the vertebrate gastrin/cholecystokinin family have been identified. 9. As the number of different neuro-/gut peptides with possible function(s) as hormone, neurotransmitter or neuromodulator is now estimated to be of the order of a few hundred, more similarities will probably show up in the near future.

Isolation and structure of two gastrin/CCK-like neuropeptides from the American cockroach homologous to the leucosulfakinins

Perisulfakinin, a peptide with sequence similarity to gastrin and cholecystokinin, was isolated from the corpora cardiaca of the American cockroach. Its sequence was determined to be Glu-Gln-Phe H-Asp-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-amide. The peptide induced hindgut contractions in the same species at concentrations as low as 250 pM. A related non-sulfated peptide was also isolated and sequenced; it was found to be identical with non-sulfated leucosulfakinin II (pGlu-Ser-Asp-Asp-Tyr-Gly-His-Met-Arg-Phe-amide). This peptide did not stimulate hindgut contractions. The structures of the cockroach peptides of the leucosulfakinin family are thus much more conserved than the cockroach hypertrehalosemic hormones.

Amino acid sequence of pheromone-biosynthesis-activating neuropeptide (PBAN) of the silkworm, Bombyx mori

We have isolated two distinct pheromone-biosynthesis-activating neuropeptides (PBAN), named PBAN-I and -II, as fully oxidized forms of Met residues from adult heads of the silkworm, Bombyx mori. PBAN-I was identical with the PBAN which we had isolated before. The complete amino acid sequence of PBAN-I, a total of 33 amino acid residues, was determined as H-Leu-Ser-Glu-Asp-Met-Pro-Ala-Thr-Pro-Ala-Asp-Gln-Glu-Met-Tyr-Gln-Pro-As p-Pro- Glu-Glu-Met-Glu-Ser-Arg-Thr-Arg-Tyr-Phe-Ser-Pro-Arg-Leu-NH2. Synthetic PBAN-I after oxidation with H2O2 was chromatographically identical with the isolated PBAN-I. Examination of PBAN activity of synthetic analogues indicated that the carboxyl-terminal portion of PBAN-I was important for biological activity.

Identification of a Neuropeptide Hormone That Regulates Sex Pheromone Production in Female Moths

A pheromone biosynthesis activating neuropeptide (PBAN) hormone that controls sex pheromone production in female moths was identified from the brain-subesophageal ganglion complexes of the adult corn earworm, Heliothis zea. PBAN has 33 amino acid residues and a molecular weight of 3900. Its amino acid sequence has no significant homology with any of the fully characterized peptide hormones. The synthetic peptide, at a dose of between 2 and 4 picomoles, induced production of a normal quantity of sex pheromone in ligated H. zea females. The peptide also induced pheromone production in six other species of moths, thus indicating that this or similar peptides may be responsible for the regulation of pheromone production in moths.

A substance resembling somatomedin C in the American cockroach

Material antigenically resembling somatomedin C (type I insulin-like growth factor, IGF-I) is demonstrated in the American cockroach Periplaneta americana by means of a monoclonal antibody immunoperoxidase technique. It was localized histochemically in neuronal cell somata and axonal fibers (probably interneurons) of the central nervous/neuroendocrine system and in 'endocrine-type' cells lining the midgut epithelium. The IGF-I-like substance is different from vertebrate insulin and also distinct from materials immunostained by different insulin antibodies in the brain and neurohaemal complex of this insect species. These findings are viewed in the light of recent reports on the presence and action of insulin-like chemicals in insects, and with respect to the existence of an insect brain-midgut system similar to the mammalian brain-gastroenteropancreatic system.

Immunocytochemical demonstration of vertebrate peptides in invertebrates: the homology concept

During the last years many positive immunocytochemical reactions have been described in invertebrates using antisera to vertebrate regulatory peptides. However, due to the specificity problems associated with immunocytochemistry, the significance of the majority of these findings remains unclear, as so far only a few of the substances causing the immunoreactions in invertebrates have been isolated. It is proposed that comparing the localizations of "vertebrate" peptides in different and not closely related species of an invertebrate group may give a clue to the physiological relevance of the immunoreactive substances.

Biological, chromatographical, and radioimmunological evidence for a melanotropin-like peptide in the central nervous system of Locusta migratoria

Our recent immunocytochemical study has demonstrated the existence of alpha-melanocyte stimulating hormone (alpha-MSH)-like material in the locust central nervous system. The aim of the present study was to further characterize alpha-MSH in the locust brain by its biological effect on frog skin and by high-pressure liquid chromatography in combination with radioimmunological and biological detection methods. Parallel radioimmunoassay (RIA) curves of crude nervous tissue extracts coupled with bioactivity in a very specific bioassay suggest similarity between the locust alpha-MSH-like substance and synthetic alpha-MSH. The highest concentration of alpha-MSH immunoreactive material in the central nervous system was found in the optic lobes, where alpha-MSH immunoreactive cell bodies are localized, as was previously shown by immunocytochemistry. High concentrations of alpha-MSH immunoreactive material were also detected in the thoracic ganglia of the locust ventral nervous system. The application of locust brain extracts to gel permeation HPLC resulted in a similar elution profile of the bioactive and immunologically active substances, both coeluting with synthetic alpha-MSH. As is the case for vertebrate brain material, reverse-phase HPLC revealed four alpha-MSH immunoreactive peaks. One of the peaks coelutes with monoacetyl-alpha-MSH and other RIA-positive material elutes at times close (but not identical) to the methionine sulfoxide forms of alpha-MSH. Peak three, however, elutes in a very different position from desacetyl-alpha-MSH. Peaks are absent in the position of desacetyl-alpha-MSH. Similarity between the locust alpha-MSH-related substance and authentic alpha-MSH is discussed.

Leucosulfakinin-II, a blocked sulfated insect neuropeptide with homology to cholecystokinin and gastrin

A sulfated neuropeptide [pGlu-Ser-Asp-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2], with a blocked N-terminus and related to the undecapeptide leucosulfakinin, has been isolated from head extracts of the cockroach, Leucophaea maderae. It exhibits sequence homology with the hormonally-active portion of vertebrate hormones cholecystokinin, human gastrin II and caerulin. This peptide, termed leucosulfakinin-II, shares a common C-terminal heptapeptide fragment with leucosulfakinin and a comparison of the two sequences provides an assessment of the importance of the constituent amino acids to biological activity. Leucosulfakinin-II shows a greater resemblance to cholecystokinin than does leucosulfakinin. Leucosulfakinin-II and leucosulfakinin are the only two reported invertebrate sulfated neuropeptides. As with leucosulfakinin, the intestinal myotropic activity of leucosulfakinin-II is analogous to that of gastrin and cholecystokinin. The sequence homology between the leucosulfakinins and the vertebrate hormones, as well as their analogous myotropic activity, suggest that gastrin/cholecystokinin-like neuropeptides are not confined to vertebrates, but also occur in invertebrates.

Leucosulfakinin, a sulfated insect neuropeptide with homology to gastrin and cholecystokinin

A sulfated, myotropic neuropeptide termed leucosulfakinin (Glu-Gln-Phe-Glu-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2) was isolated from head extracts of the cockroach Leucophaea maderae. The peptide exhibits sequence homology with the hormonally active portion of the vertebrate hormones human gastrin II and cholecystokinin, suggesting that these peptides are evolutionarily related. Six of the 11 amino acid residues (55 percent) are identical to those in gastrin II. In addition, the intestinal myotropic action of leucosulfakinin is analogous to that of gastrin.