Article

New players in the regulation of ecdysone biosynthesis

Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
Journal of Genetics and Genomics (Impact Factor: 3.59). 02/2008; 35(1):1-10. DOI: 10.1016/S1673-8527(08)60001-6
Source: PubMed

ABSTRACT

Insect ecdysone steroid hormone regulates major developmental transitions, such as molting and metamorphosis. The production of ecdysone correlates well with the timing of these transitions. Finding out how the ecdysone biosynthesis is regulated is crucial to fully understand these sophisticated developmental switches. Here we summarized recent findings in the regulation of ecdysone biosynthesis from the aspects of cell signaling, key biosynthetic enzymes and substrate cholesterol trafficking. © 2008 Institute of Genetics and Developmental Biology and the Genetics Society of China.

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    • "Importantly, however, neither the larval arrest nor pupariation delay phenotype was fully rescued by overexpressing Ras V12 , the active form of Ras that is able to completely rescue a PTTH signaling deficiency (Figures 1A and 1C) (Rewitz et al., 2009). Such partial rescue strongly suggests that, unlike previous assumptions based on moth studies (Huang et al., 2008), the intracellular calcium release mediated by IP3R is not solely functioning upstream of the MAPK signaling "
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    ABSTRACT: Steroid hormones are a large family of cholesterol derivatives regulating development and physiology in both the animal and plant kingdoms, but little is known concerning mechanisms of their secretion from steroidogenic tissues. Here, we present evidence that in Drosophila, endocrine release of the steroid hormone ecdysone is mediated through a regulated vesicular trafficking mechanism. Inhibition of calcium signaling in the steroidogenic prothoracic gland results in the accumulation of unreleased ecdysone, and the knockdown of calcium-mediated vesicle exocytosis components in the gland caused developmental defects due to deficiency of ecdysone. Accumulation of synaptotagmin-labeled vesicles in the gland is observed when calcium signaling is disrupted, and these vesicles contain an ABC transporter that functions as an ecdysone pump to fill vesicles. We propose that trafficking of steroid hormones out of endocrine cells is not always through a simple diffusion mechanism as presently thought, but instead can involve a regulated vesicle-mediated release process.
    No preview · Article · Nov 2015 · Cell
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    • "In most insects, ecdysteroids, and predominantly 20E, regulate moulting and metamorphosis, as well as some aspects of reproduction (Huang et al., 2008). Crustaceans also synthesize 20E along with ponasterone A (PoA, 25-deoxy-20E) (Lachaise & Lafont, 1984), and both have biological activity, although the role of PoA has not been studied as extensively as that of 20E (Mykles, 2011). "
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    ABSTRACT: The ecdysteroid biosynthetic pathway involves sequential enzymatic hydroxylations by a group of enzymes collectively known as Halloween gene proteins. Complete sequences for three Halloween genes, spook (Vdspo), disembodied (Vddib) and shade (Vdshd), were identified in varroa mites and sequenced. Phylogenetic analyses of predicted amino acid sequences for Halloween orthologues showed that the acarine orthologues were distantly associated with insect and crustacean clades indicating that acarine genes had more ancestral characters. The lack of orthologues or pseudogenes for remaining genes suggests these pathway elements had not evolved in ancestral arthropods. Vdspo transcript levels were highest in gut tissues, while Vddib transcript levels were highest in ovary-lyrate organs. In contrast, Vdshd transcript levels were lower overall but present in both gut and ovary-lyrate organs. All three transcripts were present in eggs removed from gravid female mites. A brood cell invasion assay was developed for acquiring synchronously staged mites. Mites within 4 h of entering a brood cell had transcript levels of all three that were not significantly different from mites on adult bees. These analyses suggest that varroa mites may be capable of modifying 7-dehydro-cholesterol precursor and hydroxylations of other steroid precursors, but whether the mites directly produce ecdysteroid precursors and products remains undetermined.
    Full-text · Article · Jun 2015 · Insect Molecular Biology
    • "Ketodiol then undergoes successive hydroxylation at C-25, C-22 and C-2 to yield ecdysone, which is converted into 1 in peripheral tissues such as the fat-body (Huang et al., 2008; Rees, 1995). The genes encoding the P450 enzymes that catalyze these hydroxylations have been characterized in insects (Huang et al., 2008). The gene encoding the desaturation of 2 to 5 has also been identified (Yoshiyama-Yanagawa et al., 2011). "
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    ABSTRACT: 3β-Hydroxy-5β-cholestan-6-one was identified in the EtOAc extract of Ajuga hairy roots by micro-analysis using LC-MS/MS in the multiple reaction mode (MRM). Furthermore, administration of (2,2,4,4,7,7-(2)H6)- and (2,2,4,4,6,7,7-(2)H7)-cholesterols to the hairy roots followed by LC-MS/MS analysis of the EtOAc extract of the hairy roots indicated that cholesterol was converted to the 5β-ketone with hydrogen migration from the C-6 to the C-5 position. These findings, in conjunction with the previous observation that the ketone was efficiently converted to 20-hydroxyecdysone, strongly suggest that the 5β-ketone is an intermediate immediately formed after cholesterol during 20-hydroxyecdysone biosynthesis in Ajuga sp. In addition, the mechanism of the 5β-ketone formation from cholesterol is discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.
    No preview · Article · Jan 2015 · Phytochemistry
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