Fig. 10.

Principal cell mesh knockdown in the adult Drosophila Malpighian tubule results in mislocalized expression of other smooth septate junction (sSJ) proteins. The main segment of a 14-day-old adult control female fly anterior tubule (w;tub-GAL80^ts20/+;c42-GAL4/+) shows Mesh expression at sSJs between all cells (A). Mesh colocalizes with Discs large (Dlg; C–C′′), tetraspanin 2A (Tsp2A; E), and Snakeskin (Ssk; G) at sSJs in control tubules. In the main segment of tubules subjected to 14-day adult principal cell mesh knockdown (w;tub-GAL80^ts20/UAS-mesh^RNAi;c42-GAL4/+), Mesh immunoreactivity at sSJs between the principal cells is either greatly reduced or undetectable and is mostly confined to the borders of the stellate cells (B, arrowheads in B′). B′ shows a higher-magnification image of dashed-box area in B. The mesh knockdown tubules also show reduced levels of Dlg at sSJs and its spread into the cytoplasm of the principal cells (D–D′′, arrows in D′′). D′′ shows a higher-magnification image of merged dashed-box areas in D and D′. Tsp2A (F and F′) and Ssk (H and H′) are mostly expressed along the edges of the stellate cells (arrowheads in F′ and H′) and inside the principal cells of mesh knockdown tubules (arrows in F’ and H’). F′ and H′ show higher-magnification images of the dashed-box areas in F and H, respectively. Nuclei were counterstained blue with DAPI. PC, principal cell; RNAi, RNA interference; SC, stellate cell. Ten samples per genotype were examined. Scale bars, 50 μm.