Characterization and influences of classical insect hormones on the expression profiles of a molting carboxypeptidase A from the cotton bollworm (Helicoverpa armigera)

Abstract

Molting is a very important physiological behavior to arthropods. During molting, integument apolysis occurs, which is the digestion and absorption of the old endocuticle for new cuticle formation. Proteases play critical roles in this process. Molting carboxypeptidase A ( Ha-CPA ) is characterized from Helicoverpa armigera . The Ha-CPA transcript was mainly present in the integument from the 5th instar larvae. In the integument, the transcription level of the gene reached its peak at the 5th instar molting stage and the 6th instar prepupal stage, respectively. The examination of immunohistochemistry revealed that Ha-CPA could distribute into the molting fluid in the molting-and prepupal-stage larvae. The expression of Ha-CPA could be up-regulated by 20-hydroxyecdysone (20E). These facts indicate that Ha-CPA participates in the apolysis of the integument during larval molting and metamorphosis.

20-hydroxyecdysone activates Forkhead box O to promote proteolysis during Helicoverpa armigera molting

“…CPA is also highly expressed during metamorphosis in H. armigera (Sui et al, 2009); therefore, FoxO could also regulate metamorphic molting. However, any effect of FoxO knockdown on metamorphic molting could not be examined in our study because the larvae died before metamorphosis after FoxO knockdown in fifth instar larvae.…”

“…CPA in the molting fluid participates in apolysis and its transcript levels are increased at the fifth instar molting stage and the sixth instar prepupal stage by 20E induction in H. armigera (Sui et al, 2009). The present study showed that FoxO knockdown leads to molting failure because of the suppression of BrZ7 and CPA expression.…”

“…A newly identified Br isoform 7 (BrZ7) increases expression during metamorphosis and regulates metamorphosis in H. armigera (Cai et al, 2014b). Carboxypeptidase A (CPA), which is encoded by another 20E-response gene, is secreted into the molting fluid by the epidermis under 20E induction to degrade old cuticle proteins during apolysis in B. mori (Ote et al, 2005) and H. armigera (Sui et al, 2009). However, the mechanism by which 20E regulates the expression of Br and the cascade of the aforementioned genes remains unclear.…”

A BTB domain‐containing gene is upregulated by immune challenge

“…The protein concentrations were analyzed according to the Bradford method (Bradford, 1976) using bovine serum albumin as the standard. Western blot was performed according to a previously described method (Sui et al, 2009). …”

“…The purified HaBBP was used as the antigen for producing polyclonal antiserum according to a previously described method (Sui et al, 2009).…”