Patterned Anchorage to the Apical Extracellular Matrix Defines Tissue Shape in the Developing Appendages of Drosophila.
Bottom Line: Here, we describe a genetic pathway that shapes appendages in Drosophila by defining the pattern of global tensile forces in the tissue.Altering Dp expression in the developing wing results in predictable changes in wing shape that can be simulated by a computational model that incorporates only tissue contraction and localized anchorage.Three other wing shape genes, narrow, tapered, and lanceolate, encode components of a pathway that modulates Dp distribution in the wing to refine the global force pattern and thus wing shape.
Affiliation: School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK; The Francis Crick Institute, Lincoln's Inn Fields Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK. Electronic address: email@example.com.Show MeSH
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Mentions: dp encodes a gigantic transmembrane protein that forms part of the apical extracellular matrix (aECM) and whose primary function is to anchor ectodermal cells to the overlying cuticle (Bökel et al., 2005; Jaźwińska et al., 2003; Wilkin et al., 2000). To characterize the distribution of Dp protein during appendage development, we have used a protein trap insertion into an N-terminal intron of dp that introduces a yellow fluorescent protein (YFP) tag into the extracellular domain of the protein, but does not affect protein function (dp-YFP, see Experimental Procedures). In the larval imaginal discs, Dp is found in a dense meshwork that uniformly covers the apical surface of the epithelium (Figure 2A). In the pupal wing, however, Dp is restricted. At the onset of hinge contraction (18 hr After Puparium Formation, APF), apically localized Dp is only found at the wing margin and to a lesser extent along the trajectories of the L3 and L5 veins (Figures 2B and 2E), while in the pupal leg and antenna, Dp is found at the extreme distal tip of the appendage (Figures 2J and 2K). As tissue contraction proceeds, de novo expression of Dp accumulates throughout the tissue (Figures 2C and 2D) such that, at 30 hr APF, it appears as a diaphanous network of enmeshed fibers that is similar in appearance to the aECM found in vertebrates (Figures 2F–2I) (Jovine et al., 2002).
Affiliation: School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK; The Francis Crick Institute, Lincoln's Inn Fields Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK. Electronic address: firstname.lastname@example.org.