The conserved transmembrane proteoglycan Perdido/Kon-tiki is essential for myofibrillogenesis and sarcomeric structure in Drosophila

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.Muscle differentiation requires the assembly of high-order structures called myofibrils, composed of sarcomeres. Even though themolecular organization of sarcomeres is well known, the mechanisms underlying myofibrillogenesis are poorly understood. It has been proposed that integrin-dependent adhesion nucleates myofibrils at the periphery of the muscle cell to sustain sarcomere assembly. Here, we report a role for the gene perdido (perd, also known as kon-tiki, a transmembrane chondroitin proteoglycan) in myofibrillogenesis. Expression of perd RNAi in muscles, prior to adult myogenesis, can induce misorientation and detachment of Drosophila adult abdominal muscles. In comparison to controls, perd-depleted muscles contain fewer myofibrils, which are localized at the cell periphery. These myofibrils are detached from each other and display a defective sarcomeric structure. Our results demonstrate that the extracellular matrix receptor Perd has a specific role in the assembly of myofibrils and in sarcomeric organization. We suggest that Perd acts downstream or in parallel to integrins to enable the connection of nascent myofibrils to the Z-bands. Our work identifies the Drosophila adult abdominalmuscles as amodel to investigate in vivo the mechanisms behind myofibrillogenesis.Research was funded by the Spanish Ministry of Science and Innovation [grant number BFU2011-26745]. B.E. was funded in part by the Ramon y Cajal program by the Universidad Pablo de Olavide; J.J.P.-M. was funded by the Proyecto de Excelencia of Junta de Andalucía; M.B. was funded by a Wellcome Trust Senior Investigator Award to Peter Lawrence [grant number WT096645MA]. M.D.M.-B. is funded by the Consejo Superior de Investigaciones Científicas.Peer Reviewe