Reference - Detail
| RRC ID | 47240 |
|---|---|
| Author | Saito J, Kimura R, Kaieda Y, Nishida R, Ono H. |
| Title | Characterization of candidate intermediates in the Black Box of the ecdysone biosynthetic pathway in Drosophila melanogaster: Evaluation of molting activities on ecdysteroid-defective larvae. |
| Journal | J Insect Physiol |
| Abstract |
Early steps of the biosynthetic pathway of the insect steroid hormone ecdysone remains the "Black Box" wherein the characteristic ecdysteroid skeleton is built. 7-Dehydrocholesterol (7dC) is the precursor of uncharacterized intermediates in the Black Box. The oxidation step at C-3 has been hypothesized during conversion from 7dC to 3-oxo-2,22,25-trideoxyecdysone, yet 3-dehydroecdysone is undetectable in some insect species. Therefore, we first confirmed that the oxidation at C-3 occurs in the fruitfly, Drosophila melanogaster using deuterium-labeled cholesterol. We next investigated the molting activities of candidate intermediates, including oxidative products of 7dC, by feeding-rescue experiments for Drosophila larvae in which an expression level of a biosynthetic enzyme was knocked down by the RNAi technique. We found that the administration of cholesta-4,7-dien-3-one (3-oxo-Δ4,7C) could overcome the molting arrest of ecdysteroid-defective larvae in which the expression level of neverland was reduced. However, feeding 3-oxo-Δ4,7C to larvae in which the expression levels of shroud and Cyp6t3 were reduced inhibited molting at the first instar stage, suggesting that this steroid could be converted into an ecdysteroid-antagonist in loss of function studies of these biosynthetic enzymes. Administration of the highly conjugated cholesta-4,6,8(14)-trien-3-one, oxidized from 3-oxo-Δ4,7C, did not trigger molting of ecdysteroid-defective larvae. These results suggest that an oxidative product derived from 7dC is converted into ecdysteroids without the formation of this stable conjugated compound. We further found that the 14α-hydroxyl moiety of Δ4-steroids is required to overcome the molting arrest of larvae in loss of function studies of Neverland, Shroud, CYP6T3 or Spookier, suggesting that oxidation at C-14 is indispensable for conversion of these Δ4-steroids into ecdysteroids via 5β-reduction. |
| Volume | 93-94 |
| Pages | 94-104 |
| Published | 2016-1-1 |
| DOI | 10.1016/j.jinsphys.2016.09.012 |
| PII | S0022-1910(16)30311-0 |
| PMID | 27662806 |
| MeSH | Animals Biosynthetic Pathways Drosophila melanogaster / growth & development Drosophila melanogaster / physiology* Ecdysone / biosynthesis* Ecdysteroids / metabolism* Larva / growth & development Larva / physiology Metamorphosis, Biological Oxidation-Reduction |
| IF | 2.246 |
| Times Cited | 5 |
| WOS Category | ENTOMOLOGY PHYSIOLOGY ZOOLOGY |
| Altmetric score |
オルトメトリクス指標項目
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| Total number of mentions | 0 |
| Altmetric score changes over past 6months | 0.0 |
| Resource | |
| Drosophila | DGRC#105669 |