Structural cuticular proteins (CPs) and the liner polysaccharide, chitin, are the primary components of insect cuticle or exoskeleton. A large number of insect CP family proteins are divided into several distinct subfamilies defined by the presence of specific amino acid sequence motifs. One of these subfamilies is composed of Cuticular Protein Analogous to Peritrophins (CPAPs), containing one (CPAP1s) or three (CPAP3s) type-2 chitin-binding domains. In this study, we report a novel function of TcCPAP1-C from Tribolium castaneum in movement of legs. RNAi for TcCPAP1-C at larval stage has no effect on insect molting, growth and development. However, the resulting adults exhibit impaired leg movement, in which internal tendon cuticles are ruptured near the femur-tibia joint. The exoskeletal cuticle, hemiadherens junctions, microtubule array, myotendinous junctions and muscle fibers exhibit normal morphology before the tendon breakage. These results indicate functional specialization of TcCPAP1-C in structural integrity of the internal tendon cuticle, and loss of function of TcCPAP1-C caused breakage of the tendon cuticle, resulting in defective limb movement and locomotion.

• Myeongjin Kim(Department of Applied Biology, Chonnam National University) Corresponding author
• Mi Young Noh(Department of Forest Resources, AgriBio Institute of Climate Change Management, Chonnam National University)
• Yasuyuki Arakane(Department of Applied Biology, Chonnam National University)