Serpentine and Vermiform Are Produced Autonomously to Fulfill Their Function in Drosophila Wings

SIMPLE SUMMARY: In Drosophila melanogaster, DmCDA1 (Serpentine, serp) and DmCDA2 (Vermiform, verm) are responsible for wing cuticle barrier establishment. In the embryo, Serp is produced in the fat body and is transported to tracheal cells to participate in tracheal development. To answer the question as to whether these CDAs in the wing tissue were produced locally or derived from the fat body, we inhibited serp and verm specifically in the fat body or the wing primordia. We revealed that Serp and Verm were produced autonomously in the wing, and repression of these two enzymes caused wing defects locally. They fulfill their function in the wing independently of their expression in fat body. This study advances the understanding of the role of chitin deacetylase in insect wing development. ABSTRACT: Group I chitin deacetylases (CDAs), CDA1 and CDA2, play an essential role in cuticle formation and molting in the process of insect wing development. A recent report showed that trachea are able to take up a secreted CDA1 (serpentine, serp) produced in the fat body to support normal tracheal development in the fruit fly Drosophila melanogaster. However, whether CDAs in wing tissue were produced locally or derived from the fat body remains an open question. To address this question, we applied tissue-specific RNAi against DmCDA1 (serpentine, serp) and DmCDA2 (vermiform, verm) in the fat body or the wing and analyzed the resulting phenotypes. We found that repression of serp and verm in the fat body had no effect on wing morphogenesis. RT-qPCR showed that RNAi against serp or verm in the fat body autonomously reduced their expression levels of serp or verm in the fat body but had no non-autonomous effect on the expression in wings. Furthermore, we showed that inhibition of serp or verm in the developing wing caused wing morphology and permeability deficiency. Taken together, the production of Serp and Verm in the wing was autonomous and independent of the fat body.