Mucin family genes are essential for the growth and development of the migratory locust, Locusta migratoria

Mucins are highly glycosylated proteins that are characterized by a higher proportion of threonine, serine, and proline residues in their sequences. Although mucins in humans and vertebrates have been implicated in many biological processes, their roles in growth and development in invertebrates such as in insects remain largely unknown. Based on bioinformatic analyses, we identified eight mucin or mucin-like genes in the migratory locust, Locusta migratoria. RNA interference against these genes demonstrated that three Lmmucin genes were essential for the survival of L. migratoria nymphs, and one Lmmucin was required for adult wing development. Indeed, knockdown of Lmhemomucin and Lmmucin-12 caused lethal phenotypes, with an observed defect of the gastric caeca in which cells were detached from cell junctions. Deficiency of LmIIM3 resulted in lethality of nymphs, with defects of the peritrophic membrane in midgut. Suppression of Lmmucin-17 greatly impaired the structural integrity of the wing cuticle during nymph-adult molting. The present study revealed the significance of mucin and mucin-like genes in insect growth and development, using the orthopteran insect locust as a model.