The core complex of cuticle dynamics in Drosophila exoskeleton. Matthias Behr, Kapil R Patil, Yanina Y Pesch, Dominik Hölper. Life & Medical Sciences (LIMES) Institute, Carl-Troll-Str. 31, 53115 Bonn, Germany.

   The arthropods cuticle plays important roles in growth control, wound healing and protects against dehydration, pathogens and toxins. It lines the apical surface of epidermis and many internal organs. Organization of the cuticle extracellular matrix (ECM) involves the polysaccharide chitin and associated proteins and enzymes. A newly synthesized cuticle requires further maturation and protection but underlying molecular mechanisms are poorly understood. We identified a core complex that is required for cuticle dynamics. Obstructor (Obst)-A (member of the obstructor multigene family) binds chitin and interacts with the cuticle modifier Knickkopf and the chitin deacetylase Serpentine. The core complex enables chitin ECM maturation and protects it from chitinase-dependent degradation. Loss of the core complex organization in obst-A mutants results in early larval lethality and cuticle integrity and molting defects. We then systematically knocked down enzymes that degrade chitin ECM in the epidermis and found severe cuticle defects similar to obst-A mutants. The presented mechanisms are required for cuticle dynamics throughout Drosophila development.