scholarly journals Regions within a single epidermal cell of Drosophila can be planar polarised independently

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Miguel Rovira ◽  
Pedro Saavedra ◽  
José Casal ◽  
Peter A Lawrence

Planar cell polarity (PCP), the coordinated and consistent orientation of cells in the plane of epithelial sheets, is a fundamental and conserved property of animals and plants. Up to now, the smallest unit expressing PCP has been considered to be an entire single cell. We report that, in the larval epidermis of Drosophila, different subdomains of one cell can have opposite polarities. In larvae, PCP is driven by the Dachsous/Fat system; we show that the polarity of a subdomain within one cell is its response to levels of Dachsous/Fat in the membranes of contacting cells. During larval development, cells rearrange (<xref ref-type="bibr" rid="bib25">Saavedra et al., 2014</xref>) and when two subdomains of a single cell have different types of neighbouring cells, then these subdomains can become polarised in opposite directions. We conclude that polarisation depends on a local comparison of the amounts of Dachsous and Fat within opposing regions of a cell's membrane.

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Pedro Saavedra ◽  
Jean-Paul Vincent ◽  
Isabel M Palacios ◽  
Peter A Lawrence ◽  
José Casal

Drosophila has helped us understand the genetic mechanisms of pattern formation. Particularly useful have been those organs in which different cell identities and polarities are displayed cell by cell in the cuticle and epidermis (<xref ref-type="bibr" rid="bib27">Lawrence, 1992</xref>; <xref ref-type="bibr" rid="bib5">Bejsovec and Wieschaus, 1993</xref>; <xref ref-type="bibr" rid="bib17">Freeman, 1997</xref>). Here we use the pattern of larval denticles and muscle attachments and ask how this pattern is maintained and renewed over the larval moult cycles. During larval growth each epidermal cell increases manyfold in size but neither divides nor dies. We follow individuals from moult to moult, tracking marked cells and find that, as cells are repositioned and alter their neighbours, their identities change to compensate and the pattern is conserved. Single cells adopting a new fate may even acquire a new polarity: an identified cell that makes a forward-pointing denticle in the first larval stage may make a backward-pointing denticle in the second and third larval stages.


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