interacts with to Regulate Myonuclear Positioning and Microtubule Organization.

Unlabelled: During myognesis, myonuclei are actively moved during embryogenesis, and their spacing is maintained through an anchoring mechanism in the fully differentiated myofiber. While we have identified microtubule associated proteins, motors, and nuclear envelope proteins that regulate myonuclear spacing, the developmental time during which each gene functions has not been tested. Here we have identified a as required only for the maintenance of myonuclear spacing. Furthermore, we demonstrate that genetically interacts with the KASH-domain protein to maintain myonuclear spacing. Mechanistically, both and regulate microtubule organization. Specifically, in animals with disrupted expression of both and , microtubule colocalization with sarcomeres is reduced. Taken altogether, these data indicate that the peripheral membrane protein Dystrophin, and the outer nuclear membrane protein Msp300, together regulate the organization of the microtubule network which then acts as an anchor to restrict myonuclear movement in contractile myofibers. These data are consistent with growing evidence that myonuclear movement and myonuclear spacing are critical to muscle development, muscle function, and muscle repair and provide a mechanism to connect disparate muscle diseases.

Summary Statement: Here we show that is required to maintain the spacing of nuclei in differentiated myofibers. Furthermore, achieves this function via a genetic interaction with which regulates microtubule organization.