Retroactive, a membrane‐anchored extracellular protein related to vertebrate snake neurotoxin‐like proteins, is required for cuticle organization in the larva of Drosophila melanogaster

Abstract

Mutations in the rtv gene cause disarrangement of chitin fibers in the cuticle of the Drosophila larva, and occasionally the cuticle detaches from the epidermis. We have identified the rtv gene, and using the new HHpred homology detection method, we show that the Rtv protein defines a new family of disulfide-rich proteins in insects that are related to vertebrate snake neurotoxin-like proteins, including CD59 and transforming growth factor-␤ type II receptors. Rtv is an extracellular membrane-anchored protein exposing six aromatic residues that may mediate binding to chitin. We propose that this binding function of Rtv may assist the organization of chitin fibers at the epidermal cell surface during cuticle assembly.

Recent advances in understanding mechanisms of insect cuticle differentiation

“…In D. melanogaster larvae mutant for factors that are required to produce or organize chitin microfibrils epicuticle uniformity is lost (Moussian et al, 2005a(Moussian et al, , 2005b(Moussian et al, , 2006b. Taken together, the epicuticle is a complex extracellular matrix that is constructed by the parallel and cooperative activity of cytoplasmic, membraneassociated and extracellular processes.…”

“…Moreover, the genetic accessibility of D. melanogaster allows the identification of crucial cuticle factors that would not have been identified biochemically, e.g. Knickkopf (Knk) and Retroactive (Rtv) (Moussian et al, 2005b(Moussian et al, , 2006b. Thank to the relatively conserved cuticle structure between species, findings in D. melanogaster can readily be related to the enormous amount of data collected in other insect species.…”

Mutation of TweedleD, a member of an unconventional cuticle protein family, alters body shape in Drosophila

“…Mutations in Drosophila that disrupt the synthesis, modification, or deposition of chitin have been identified for a number of loci, including the genes for chitin synthase (kkv), UDP-Nacetylglucosamine pyrophosphorylase (mummy), and chitinmodifying proteins (serpentine, vermiform, knickkopf, and retroactive) (14)(15)(16)(17)(18)(19)(20)(21). In each case, gene inactivation results in a dilated or deformed cuticle.…”

Knickkopf and retroactive proteins are required for formation of laminar serosal procuticle during embryonic development of Tribolium castaneum

“…The roles of Chs-A, Knk and Rtv in the formation and assembly of chitin in post-embryonic (larval, pupal and adult) cuticles of epidermal origin have been studied previously (Arakane et al, 2005b(Arakane et al, , 2008Chaudhari et al, 2011;Moussian et al, 2005aMoussian et al, , 2005bMoussian et al, , 2006Ostrowski et al, 2002). Unlike post-embryonic stages, during embryogenesis there are three different types of cuticles produced.…”