Adipokinetic hormones (AKHs) are metabolic neuropeptides, mediating mobilization of energy substrates in many insects.

History

An English group first purified AKH in 1976. The chemical structure was determined to be a peptide hormone formed from 10 amino acids. This was the first insect peptide hormone to be identified.[1] After AKH was identified in cockroaches, locust AKH was inserted into a cockroach. A similar increase in lipid mobilization was observed. Conversely, cockroach AKH led to similar activity within a locust.[1] AKH was initially discovered in the locusts Locusta migratoria and Schistocerca gregaria. It is generally associated with aiding flight.[2] Lipids are transported from the hemolymph and metabolized by flight muscle in order to maintain flight. However, a high concentration of lipids remains in the hemolymph, implying that an agent may be responsible for activating lipid transport into the hemolymph. This was thought most likely to be a function of hormonal regulation.[1] The hormone itself is part of a larger family, often referred to as red pigment concentrating hormones (RPCH) discovered in crustaceans.

Sequence

The typical makeup of hormones in this family includes a length between 8 and 10 amino acids, blocked N and C termini, with phenylalanine or tyrosine at position 4.[2] AKH sequence characteristics also include tryptophan at position 8 and in more than half of the known AKHs, proline at position 6.[3][4] Mass spectrometry is increasingly used for de novo sequencing of these hormones.[5][6][7]

Significance

AKH has become an important area of study, particularly in insect crop pests and insects that act as intermediate or vector hosts for parasites that can affect humans or animals. In experiments where locusts were injected with AKH and lipopolysaccharide (LPS–an immune elicitor found in the cell walls of bacteria) a stronger immune response was observed than in locusts that only received an LPS injection.[8][9] The spread of malaria by the female mosquito, Anopheles gambiae, is partly dependent on the adipokinetic hormone, Anoga-HrTH (pGlu-Leu-Thr-Phe-Thr-Pro-Ala-Trp-NH2). No crystal structure of this important neuropeptide is available. The NMR restrained molecular dynamic was used to investigate its conformational space in aqueous solution and when bound to a membrane surface. The results showed that Anoga-HrTH has an almost cyclic conformation that is stabilized by a hydrogen bond between the C-terminus and Thr3. When the agonist docks to its receptor, this H-bond is broken and the molecule adopts a more extended structure. Preliminary AKHR docking calculations give the free energy of binding to be −47.30 kJ/mol. Information about the 3D structure and binding mode of Anoga-HrTH to its receptor are vital for the design of suitable mimetics which can act as insecticides.[10]

Literature

  • "AKH: A hormone for all seasons?". Advances in invertebrate (neuro)endocrinology : a collection of reviews in the post-genomic era. Oakville, ON, Canada: Apple Academic Press. 2020. p. 129. ISBN 9780429264450.

References

  1. 1 2 3 "Chapter Eleven - HEMOLYMPH TRANSPORT OF METABOLITES: ENDOCRINE REGULATION". June 7, 2008. Archived from the original on 2008-06-07.
  2. 1 2 Stone, Judith V.; Mordue, William; Batley, Karen E.; Morris, Howard R. (September 1976). "Structure of locust adipokinetic hormone, a neurohormone that regulates lipid utilisation during flight". Nature. 263 (5574): 207–211. doi:10.1038/263207a0. ISSN 0028-0836. PMID 958472. S2CID 4226013.
  3. ↑ König, Simone (30 July 2005). "Prediction of insect adipokinetic hormone sequences assists in de novo structure elucidation". Rapid Communications in Mass Spectrometry. 19 (14): 2103–2104. doi:10.1002/rcm.2017. ISSN 0951-4198. PMID 15988719.
  4. ↑ Eisenacher, Martin; de Braaf, Jürgen; König, Simone (2006). "Mass analysis sequence prediction (MAPSP)". Bioinformatics. 22 (8): 1002–1003. doi:10.1093/bioinformatics/btl052. PMID 16500935.
  5. ↑ König, Simone; Albers, Christian; Gäde, Gerd (15 November 2005). "Mass spectral signature for insect adipokinetic hormones". Rapid Communications in Mass Spectrometry. 19 (21): 3021–3024. doi:10.1002/rcm.2167. ISSN 0951-4198. PMID 16193531.
  6. ↑
    Alavez-Rosas, David; Vargas-Abasolo, Reyna; Albores-Flores, Claudia I.; Meneses-Arias, María Guadalupe; Gutiérrez-Cabrera, Ana Erika; Benelli, Giovanni; Cruz-López, Leopoldo; Córdoba-Aguilar, Alex (2023). "Chemical ecology of triatomines: current knowledge and implications for Chagas disease vector management". Journal of Pest Science. Springer Science and Business Media LLC. doi:10.1007/s10340-023-01678-6. ISSN 1612-4758. S2CID 260819708.
    This review cites this research.
    Marco, Heather G.; König, Simone; Gäde, Gerd (January 2022). "Mass Spectrometric Proof of Predicted Peptides: Novel Adipokinetic Hormones in Insects". Molecules. 27 (19): 6469. doi:10.3390/molecules27196469. ISSN 1420-3049. PMC 9573411. PMID 36235010.
  7. ↑ König, Simone; Bayer, Malte; Marco, Heather; Gäde, Gerd (July 2019). "The hypertrehalosaemic neuropeptide conformational twins of cicadas consist of only l-amino acids: are they cis–trans isomers?". Amino Acids. 51 (7): 1023–1028. doi:10.1007/s00726-019-02742-1. PMID 31073692. S2CID 254074930.
  8. ↑ Goldsworthy, G., K. Opoku-Ware, and L. Mullen, Adipokinetic hormone enhances laminarin and bacterial lipopolysaccharide-induced activation of the prophenoloxidase cascade in the African migratory locust Locusta migratoria. Journal of Insect Physiology, 2002. 48: p. 601-608
  9. ↑ Goldsworthy, G.J., K. Opoku-Ware, and L.M. Mullen, Adipokinetic hormone and the immune responses of locusts to infection. Annals of the New York Academy of Science, 2005. 1040: p. 106-113
  10. ↑ Mugumbate G, Jackson GE, van der Spoel D, Kövér KE, Szilágyi L. Anopheles gambiae, Anoga-HrTH hormone, free and bound structure--a nuclear magnetic resonance experiment. Peptides. 2013 Mar;41:94-100. DOI: 10.1016/j.peptides.2013.01.008.
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