Mesenchymal-to-epithelial transition of intercalating cells in Drosophila renal tubules depends on polarity cues from epithelial neighbours.
Bottom Line: We also show that expression of basolateral proteins in stellate cells is a prerequisite for their ingression between principal cells.We present a model in which the contacts with successive principal cell membrane domains made by stellate cells as they integrate between them act as a cue for the elaboration of stellate cell polarity.We suggest that the formation of zonula adherens junctions between new cell neighbours establishes their apico-basal positions and stabilises them in the epithelium.
Affiliation: Institut de Biologia Molecular de Barcelona-CSIC, Parc Cientific de Barcelona, 08028 Barcelona, Spain.Show MeSH
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Mentions: Previous work has shown that the stellate cells integrate into the tubules during stages 13–15 of embryogenesis (Denholm et al., 2003). In order to assess precisely when the integration of the stellate cells takes place, and to understand the behaviour of stellate cells during renal tubulogenesis, we labelled stellate cells with a membrane-bound GFP using G447.2, a Gal4 line that positively marks stellate cells (Denholm et al., 2003). Stellate cells were first detected in the tubules during stage 13, when the renal tubules are curved structures, with the anterior tubules folding back on themselves roughly 2/3 along their length, forming a ‘kink’. It is on the inner face of the kink region that stellate cells are first found during early stage 13 (Fig. 1A). By mid-late stage 14 the process of stellate cell intercalation into the tubules is complete. While those found in the kink region, and just proximal to the kink remain clustered together, stellate cells found more distally in the tubules tend to be separated by principal cells (Fig. 1B). During stages 15 and 16 the proportion of stellate cells separated by principal cells increases, so that they are found increasingly spaced out along the future secretory domain of the tubules (Fig. 1C and D).
Affiliation: Institut de Biologia Molecular de Barcelona-CSIC, Parc Cientific de Barcelona, 08028 Barcelona, Spain.