Successively expressed cuticular protein genes at the prepupal stage in wing discs of Bombyx mori

Abstract

Background We classified cuticular protein genes expressed at prepupal stage in wing discs of Bombyx mori into six groups according to their developmental expression and ecdysone responsiveness. Their expression pattern is suggested to be regulated by ecdysone-responsive transcription factors, whose transcripts showed resemblance with those of cuticular protein gene expression. Result Group1 and Group2 CP genes showed peak expression at stage W2. Group3 CP genes showed high expression at stage W3E and W3L and were upregulated by 20E addition, showing a peak 12 h after 20E pulse treatment. Group4 CP gene transcripts started expression from stage V5 and peaked at stage W3L. Some genes showed significant increase 4 or 6 h after 20E addition and were induced 6 h and showed a peak 18 h after the 20E pulse treatment. Group5 CP gene transcripts peaked at the same stage W3L. Some Group5 genes showed significant increase 6 h after the 20E addition, while others were not induced by the 20E addition. These different sub-groups showed different expression profiles in the feeding stage. Transcripts of this group genes were induced 12 h and showed a peak 18 h after the 20E pulse treatment. Group6 CP genes peaked at the stage P0, were not induced by the 20E addition, and showed a peak 24 h after the 20E pulse treatment. Group3, 4, 5, and 6 CP genes are suggested to be regulated by BHR4, BR-C, E74A, and βFTZ-F1, respectively. ERTFs showed different responsiveness to 20E concentration. BR-C was most and E74A was least insensitive. The addition of cycloheximide inhibited BR-C, E74A, and βFTZ-F1 expression depending on the length of treatment after ecdysone pulse treatment, which suggests that BHR4 induced BR-C, E74A, and βFTZ-F1. Conclusion Expression patterns of CPs were determined by the ecdysone-responsiveness and the related ERTFs expressed in the prepupal stage in B. mori wing discs.

Transcriptional Profiling Shows that BHR4 and E74A Are the Regulators of CPH33 and CPH34 Gene Expression

“…Thus, cuticular protein genes, which have different developmental profiles, were induced by different types of ecdysone signal, and these things were described in a recent review [7].The determination of insect genomic sequences also brought about the comprehensive analysis of cuticular-protein gene expression and the analysis of its regulation by transcription factors [8][9][10][11][12][13][14][15][16][17]. Cuticular protein genes have different expression profiles [8][9][10][11][12][13][14][15][16][17] and regulatory systems by ecdysone-responsive transcription factors [9][10][11][12][13][14][15][16][17][18][19]. From this, insect cuticular protein genes are suggested to be a suitable material for clarifying the regulatory mechanism of ecdysone-responsive transcription factors.…”

Transcriptional regulation of cuticular genes during insect metamorphosis

“…Expression pattern of "Group 6" CP genes, BmorCPR45, BmorCPR55, BmorCPR92, and BmorCPR99, in vivo correspond to the pattern of βFTZ-F1, and their levels increase gradually from W2, reaching their highest levels around the peak period of pupal molting (42,44,50,51). Furthermore, Group 6 genes BmorCPT2, CPH1, and CPH2 also show similar expression patterns to βFTZ-F1 (45,47,51). In order to consider whether this grouping method according to developmental expression profiles is reasonable to investigate the mechanism of regulation of wing disc development, the next section will discuss the in vitro response of CPs to 20E, and the involvement of ecdysone-related genes.…”

“…The peak expression of Group 2 in vivo is observed a little after the peak of Group 1 (44). Expression patterns of the "Group 3" genes BmorCPR34 and BmorCPH33 resemble the pattern of the ecdysone early late gene BHR4, the transcript levels of which increase early on the fourth day of the wandering stage (W3E) and show a broad expression peak around W3E and late in W3 (W3L) (44)(45)(46). Expression of "Group 4" genes (BmorCPG11, BmorCPG13, and BmorCPH30) increases from W0 and reaches a peak on W3L (44,47,48).…”