miranda localizes staufen and prospero asymmetrically in mitotic neuroblasts and epithelial cells in early Drosophila embryogenesis

When neuroblasts divide, prospero protein and mRNA segregate asymmetrically into the daughter neuroblast and sibling ganglion mother cell. miranda is known to localize prospero protein to the basal cell cortex of neuroblasts while the staufen RNA-binding protein mediates prospero mRNA localization. Here we show that miranda is required for asymmetric staufen localization i n neuroblasts. Analyses using miranda mutants reveal that prospero and stau fen interact with miranda under the same cell-cycle-dependent control. mira nda thus acts to partition both prospero protein and mRNA, Furthermore, mir anda localizes prospero and staufen to the basolateral cortex in dividing e pithelial cells, which express the three proteins prior to neurogenesis. Ou r observations suggest that the epithelial cell and neuroblast (both of epi thelial origin) share the same molecular machinery for creating cellular as ymmetry.