TY - JOUR TI - Myofibril diameter is set by a finely tuned mechanism of protein oligomerization in Drosophila AU - González-Morales, Nicanor AU - Xiao, Yu Shu AU - Schilling, Matthew Aaron AU - Marescal, Océane AU - Liao, Kuo An AU - Schöck, Frieder A2 - Schnorrer, Frank A2 - Akhmanova, Anna A2 - Schnorrer, Frank VL - 8 PY - 2019 DA - 2019/11/20 SP - e50496 C1 - eLife 2019;8:e50496 DO - 10.7554/eLife.50496 UR - https://doi.org/10.7554/eLife.50496 AB - Myofibrils are huge cytoskeletal assemblies embedded in the cytosol of muscle cells. They consist of arrays of sarcomeres, the smallest contractile unit of muscles. Within a muscle type, myofibril diameter is highly invariant and contributes to its physiological properties, yet little is known about the underlying mechanisms setting myofibril diameter. Here we show that the PDZ and LIM domain protein Zasp, a structural component of Z-discs, mediates Z-disc and thereby myofibril growth through protein oligomerization. Oligomerization is induced by an interaction of its ZM domain with LIM domains. Oligomerization is terminated upon upregulation of shorter Zasp isoforms which lack LIM domains at later developmental stages. The balance between these two isoforms, which we call growing and blocking isoforms sets the stereotyped diameter of myofibrils. If blocking isoforms dominate, myofibrils become smaller. If growing isoforms dominate, myofibrils and Z-discs enlarge, eventually resulting in large pathological aggregates that disrupt muscle function. KW - myofibril assembly KW - aggregate formation KW - Zasp proteins KW - Alp/Enigma family proteins KW - muscle development KW - LIM domain JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -