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


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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    • "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.
    Insect Molecular Biology 06/2015; 24(3). DOI:10.1111/imb.12155 · 2.59 Impact Factor
    • "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.
    Phytochemistry 01/2015; 111. DOI:10.1016/j.phytochem.2014.12.019 · 2.55 Impact Factor
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    • "The majority of unigenes were clustered in the 'Metabolic pathways' (2,929, 15.65%) followed by 'Pathways in cancer' (746, 3.99%) and 'Regulation of actin cytoskeleton' (666, 3.56%) (Additional File 6: Table S6). Several unigenes identified belonged to prothoracicotropic hormone (PTTH) receptor signalling transduction 45 and steroid hormone biosynthesis pathways (Table 2) 46, as well as circadian rhythm 47. Some unigenes were identified in the insulin signalling pathway which is a conserved pathway in insect diapause controlling (Figure 2) 48. "
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    ABSTRACT: Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal diapause duration of this fly is a major bottleneck for artificial rearing and underlying mechanisms remain unknown. Genetic information on B. minax transcriptome and gene expression profiles are needed to understand its pupal diapause. High-throughput RNA-seq technology was used to characterize the B. minax transcriptome and to identify differentially expressed genes during pupal diapause development. A total number of 52,519,948 reads were generated and assembled into 47,217 unigenes. 26,843 unigenes matched to proteins in the NCBI database using the BLAST search. Four digital gene expression (DGE) libraries were constructed for pupae at early diapause, late diapause, post-diapause and diapause terminated developmental status. 4,355 unigenes showing the differences expressed across four libraries revealed major shifts in cellular functions of cell proliferation, protein processing and export, metabolism and stress response in pupal diapause. When diapause was terminated by 20-hydroxyecdysone (20E), many genes involved in ribosome and metabolism were differentially expressed which may mediate diapause transition. The gene sets involved in protein and energy metabolisms varied throughout early-, late- and post-diapause. A total of 15 genes were selected to verify the DGE results through quantitative real-time PCR (qRT-PCR); qRT-PCR expression levels strongly correlated with the DGE data. The results provided the extensive sequence resources available for B. minax and increased our knowledge on its pupal diapause development and they shed new light on the possible mechanisms involved in pupal diapause in this species.
    International journal of biological sciences 09/2014; 10(9):1051-63. DOI:10.7150/ijbs.9438 · 4.51 Impact Factor
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