Developmental expression and hormonal responsiveness of cuticular protein genes at the prepupal stage in wing discs of Bombyx mori.

The present study was conducted to clarify the developmental expression and hormonal responsiveness of cuticular protein genes of Bombyx mori expressed in wing discs at prepupal stage. The cuticular protein genes that showed the same expression timing with each transcription factor were selected and examined their ecdysone responsiveness. Hence, two cuticular protein genes CPH33 and CPR93 were considered for the study. CPH33 transcripts rapidly increased from W2, remained at a high level until the W3M stage, and then decreased from the W3L stage. CPR93 transcripts showed a different expression profile. They increased from the W3M stage and peaked at the W3L stage, then decreasing from P0. CPH33 and CPR93 were induced by the ecdysone addition and by the ecdysone pulse also. The developmental expression and ecdysone responsiveness of CPH33 and CPR93 resembled BHR4 and E74A respectively. Thus, ecdysone-responsive transcription factors regulated different cuticular protein genes and determined their expression timing.