Sinuous Is a Claudin Required for Locust Molt in .

The epidermal cells of insects are polarized epithelial cells that play a pivotal role in the insect's molting process. Sinuous, a pivotal structural protein involved in the formation of septate junctions among epithelial cells, is essential for its physiological function. In this study, to determine whether sinuous participates in the regulation of insect molting, we identified the sinuous gene, , in , which encodes a protein belonging to the claudin family and shares 62.6% identity with 's sinuous protein. is expressed in multiple tissues, and its expression level in the integument significantly increases prior to molting. Knockdown of in results in larval mortality during molting. Furthermore, hematoxylin and eosin and chitin staining demonstrate that the downregulation of led to a prolonged degradation process of the old cuticle during the molting process. Electron microscopy analysis further revealed that knockdown of disrupts the formation of septate junctions among epidermal cells, which are a monolayer of polarized epithelial cells, which may hinder the functionality of epidermal cells during the process of molting. In summary, these findings suggest that plays a role in nymph molting by regulating the formation of septate junctions among epidermal cells.