Insect development and metamorphosis are regulated by two major hormones, juvenile hormone and ecdysteroids. Despite being the key regulator of insect developmental transitions, the metabolic pathway of the primary steroid hormone, 20-hydroxyecdysone (20E), especially its inactivation pathway, is still not completely elucidated. A cytochrome P450 enzyme, CYP18A1, has been shown to play key roles in insect steroid hormone inactivation through 26-hydroxylation. Here, we identified two CYP18 (. BmCYP18A1 andBmCYP18B1) orthologs in the lepidopteran model insect, Bombyx mori. Interestingly, BmCYP18A1 gene is predominantly expressed in the middle silk gland (MSG) while BmCYP18B1 expresses ubiquitously in B.mori. BmCYP18A1 is induced by 20E invitro, suggesting its role in 20E metabolism. Using the binary Gal4/UAS transgenic system, we ectopically overexpressed BmCYP18A1 in a MSG-specific manner with a Sericin1-Gal4 (. Ser-Gal4) driver or in a ubiquitous manner with an Actin3-Gal4 (. A3-Gal4) driver. Ectopic overexpression of BmCYP18A1 in MSG or in all tissues resulted in developmental arrestment of transgenic animals during the final instar larval stage. The 20E titers in the transgenic animals expressing BmCYP18A1 were lower compared to the levels in the control animals. Although the biological significance of MSG-specific expression of BmCYP18A1 is unclear, our results provide the first evidence that BmCYP18A1, which is conserved in most arthropods, is involved in a tissue-specific steroid hormone inactivation in B.mori.
|Number of pages||9|
|Journal||Insect Biochemistry and Molecular Biology|
|State||Published - Aug 27 2014|
Bibliographical noteFunding Information:
This work was supported by grants from National Basic Research Program of China ( 2012CB114101 ), National Natural Science Foundation of China ( 31272037 and 31372257 ) and the Shanghai Committee of Science and Technology, China ( 11JC1413900 ).
© 2014 Elsevier Ltd.
- Bombyx mori
- Middle silk gland
ASJC Scopus subject areas
- Molecular Biology
- Insect Science