Figure 12.

The chart to interpret the mechanisms of CTSD expression, maturation, secretion, and the dual functions in tissue remodeling under 20E regulation. (A) The time of different events during H. armigera development. (B) Mechanisms of CTSD plays dual functions. In the larval midgut, 20E upregulates CTSD expression and maturation during metamorphic molting. 20E via autophagy triggers G-pro-CTSD maturation to G-m-CTSD, which is retained inside the midgut cells to promote apoptosis by inducing CASP3 cleavage. In the pupal epidermis, G-pro-CTSD was secreted to hemolymph, and N233 glycosylation determines G-pro-CTSD secretion. In the hemolymph, the G-pro-CTSD promotes endoreplication, cell proliferation, and reassociation of the adult fat body. pre: signal peptide; pro: pro-peptide; Autolyso: autolysosome; C-CASP3: cleaved-CASP3