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Bombyx E75 isoforms display stage- and tissue-specific responses to 20-hydroxyecdysone.
Kang Li1, Enen Guo1, Muktadir S Hossain2
11] Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding/Guangdong Provincial Sericulture and Mulberry Engineering Research Center, College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, China [2] Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
The silkworm E75 gene produces three mRNA isoforms (BmE75A, BmE75B, BmE75C) that respond differently to ecdysteroid hormones. These BmE75 isoforms are regulated by 20-hydroxyecdysone (20E) and other factors, showing tissue-specific expression.
Area of Science:
- * Molecular Endocrinology
- * Insect Physiology
- * Gene Regulation
Background:
- * The nuclear receptor gene E75 in Bombyx mori produces three mRNA isoforms (BmE75A, BmE75B, BmE75C) via alternative splicing.
- * Ecdysteroids are critical insect hormones regulating development and reproduction.
- * The precise regulation of E75 isoforms during development is not fully understood.
Purpose of the Study:
- * To investigate the developmental profiles and hormonal regulation of BmE75 mRNA and protein isoforms.
- * To determine the role of 20-hydroxyecdysone (20E) in regulating BmE75 expression.
- * To elucidate the relationship between BmE75 isoforms and the ecdysteroid receptor complex (EcR-USP).
Main Methods:
- * Analysis of BmE75 mRNA and protein levels during different larval and prepupal stages.
- * Treatment experiments using 20-hydroxyecdysone (20E) and cycloheximide (CHX).
- * RNA interference (RNAi) to reduce EcR-USP gene expression.
Main Results:
- * BmE75A mRNA and protein levels in prothoracic glands mirrored ecdysteroid titers during development.
- * In fat body, BmE75 mRNA levels correlated with ecdysteroid titer, but protein levels showed distinct changes, including disappearance and modification at prepupal stages.
- * BmE75A is a primary 20E-responsive gene, while BmE75B and BmE75C exhibit varied responses.
- * Reduction of EcR-USP levels significantly decreased BmE75 isoform expression in both tissues.
Conclusions:
- * BmE75 isoforms display stage- and tissue-specific responses to 20E at both mRNA and protein levels.
- * Ecdysteroid hormones, particularly 20E, play a significant role in regulating BmE75 expression.
- * Post-transcriptional or post-translational mechanisms, involving unknown factors, also regulate BmE75 protein levels.
