PROSTAGLANDINS AND OTHER EICOSANOIDS IN INSECTS: BIOSYNTHESIS AND BIOLOGICAL ACTIONS
- 1Agricultural Research Service, Biological Control of Insects Research Laboratory (USDA-ARS), United States
- 2Department of Plant Medicine, Andong National University, South Korea
This essay reviews the discoveries, synthesis and biological significance of prostaglandins (PGs) and other eicosanoids in insect biology. It presents the most current – and growing – understanding of the insect mechanism of PG biosynthesis, provide an updated treatment of known insect phospholipase A2 (PLA2), and detail contemporary findings on the biological roles of PGs and other eicosanoids in insect physiology, including reproduction, fluid secretion, hormone actions in fat body, immunity and eicosanoid signaling and cross-talk in immunity. It completes the essay with a prospectus meant to illuminate research opportunities for interested readers. In more detail, cellular and secretory types of PLA2, similar to those known on the biomedical background, have been identified in insects and their roles in eicosanoid biosynthesis documented. It highlights recent findings showing that eicosanoid biosynthetic pathway in insects is not identical to the solidly established biomedical picture. The relatively low concentrations of arachidonic acid (AA) present in insect phospholipids (< 0.1% in some species) indicate that PLA2 may hydrolyze linoleic acid (LA) as a precursor of eicosanoid biosynthesis. The free LA is desaturated and elongated into AA. Unlike vertebrates, AA is not oxidized by cyclooxygenase, but by a specific peroxidase called peroxinectin to produce PGH2, which is then isomerized into cell-specific PGs. In particular, PGE2 synthase recently identified converts PGH2 into PGE2. In the cross-talks with other immune mediators, eicosanoids act as downstream signals because any inhibition of eicosanoid signaling leads to significant immunosuppression. Because host immunosuppression favors pathogens and parasitoids, some entomopathogens evolved a PLA2 inhibitory strategy activity to express their virulence.
Keywords: Insects, Reproduction, Prostaglandins, Immunity, hormone signaling, phospholipase A2
Received: 16 Nov 2018;
Accepted: 21 Dec 2018.
Edited by:Davide Malagoli, University of Modena and Reggio Emilia, Italy
Reviewed by:Daniele P. Castro, Fundação Oswaldo Cruz (Fiocruz), Brazil
Christophe Morisseau, University of California, Davis, United States
Copyright: © 2018 Stanley and Kim. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. David Stanley, Biological Control of Insects Research Laboratory (USDA-ARS), Agricultural Research Service, Columbia, 65203, MO, United States, email@example.com