The LINC complex and microtubule motors regulate the number and position of nuclei in the subperineurial glial cells of the <i>Drosophila</i> blood-brain barrier

Syncytia provide a unique system in which to understand the mechanisms of cellular organization. Two dramatic features of syncytial cells are the number of nuclei and the positioning of nuclei within a shared cytoplasm. Whether the formation of the syncytia and the organization of the syncytia are linked is not known. We have characterized the subperineurial glial cells (SPG), which form the most restrictive layer of the <i>Drosophila</i> blood-brain barrier. We found that disruption of the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex, Kinesin, or cytoplasmic Dynein affected both SPG cell development and general brain development. Specifically, the brains were smaller in each case, and the SPG cells were smaller when the LINC complex or cytoplasmic Dynein were disrupted. The number of nuclei per cell was increased when Kinesin was disrupted and decreased when cytoplasmic Dynein was disrupted. Finally, the positions of nuclei relative to their nearest neighbor were decreased when the expression of each gene was disrupted, and nuclei were closer to the cell edge when either Kinesin or cytoplasmic Dynein was disrupted. Together, these data illustrate that the formation of SPG cells and the organization of SPG cells are dependent on microtubule motors and the LINC complex.