Skeletal muscle cells contain many nuclei that undergo complex movements; these are important for muscle function as mispositioning of nuclei is observed in disorders such as Emery–Dreifuss muscular dystrophy (EDMD). EDMD is caused by mutations in genes encoding nuclear envelope proteins, including emerin and members of the linker of nucleoskeleton and cytoskeleton (LINC) complex, which can mechanically link the nucleus to the cytoskeleton and regulate gene expression. However, it is unclear how overall nuclear movement is coordinated. In this work (Mandigo et al., 2019), Eric Folker and colleagues utilise Drosophila, which has two emerin homologues, Bocksbeutel (Bocks) and Otefin (Ote), to understand emerin-dependent nuclear positioning. They show that depletion of bocks, ote or the LINC component klarsicht (klar) all disrupt nuclear positioning in muscles. However, the specific phenotypes are different and point to opposing functions. Bocks mutants exhibit a reduced accumulation of Klar at the nuclear envelope and a disruption of nuclear separation. In contrast, in ote mutants, nuclei prematurely separate, which correlates with an increase in Klar expression and its nuclear localisation. Consistently, nuclear positioning and Klar levels are normal in the bocks; ote double mutant. These findings indicate that nuclear positioning can be disrupted by both a reduction and an increase in LINC components, and thus could provide new insights into associated diseases.
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