Dpp controls growth and patterning in Drosophila wing precursors through distinct modes of action.

Pablo Sanchez Bosch,Konrad Basler,Ruta Ziukaite,Jean-Paul Vincent,Cyrille Alexandre

doi:10.7554/elife.22546

Pablo Sanchez Bosch, Konrad Basler + Show 3 more

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https://doi.org/10.7554/elife.22546

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Journal: eLife	Publication Date: Jul 4, 2017
Citations: 62	License type: CC BY 4.0

Affiliation: University of Zurich, The Francis Crick Institute

Abstract

Dpp, a member of the BMP family, is a morphogen that specifies positional information in Drosophila wing precursors. In this tissue, Dpp expressed along the anterior-posterior boundary forms a concentration gradient that controls the expression domains of target genes, which in turn specify the position of wing veins. Dpp also promotes growth in this tissue. The relationship between the spatio-temporal profile of Dpp signalling and growth has been the subject of debate, which has intensified recently with the suggestion that the stripe of Dpp is dispensable for growth. With two independent conditional alleles of dpp, we find that the stripe of Dpp is essential for wing growth. We then show that this requirement, but not patterning, can be fulfilled by uniform, low level, Dpp expression. Thus, the stripe of Dpp ensures that signalling remains above a pro-growth threshold, while at the same time generating a gradient that patterns cell fates.

Highlights

We focus on the role of Dpp, which is expressed along the anterior-posterior (A/P) compartment boundary in a pattern that cuts across the prospective notum, hinge and wing proper (Figure 1A)
Note that the down-regulation of Brinker around residual Dpp expression in the hinge did not extend into the pouch, suggesting that Dpp produced in the hinge has little effect on gene expression in the pouch
This basic tenet was recently challenged with a conditional dpp allele that can be inactivated in time and space by Flp

Summary

Introduction

Tissue growth must be precisely coupled with patterning to ensure that the right number of cells can contribute to the various substructures within each organ (Restrepo et al, 2014) (Baena-Lopez et al, 2012; Bryant and Gardiner, 2016; Hariharan, 2015; Irvine and Harvey, 2015; Johnston and Gallant, 2002; Wartlick et al, 2011a). Segregation of wing imaginal discs into the territories that give rise to these three structures is controlled by a series of signalling events involving EGFR, JAK/STAT, Notch, and Hedgehog signalling, culminating in sustained expression of Wingless and Dpp in orthogonal stripes until the end of the third instar (Blackman et al, 1991; Neumann and Cohen, 1996; Zecca et al, 1995) Both Wingless and Dpp are essential for growth (Baena-Lopez et al, 2009; Burke and Basler, 1996; Restrepo et al, 2014; Spencer et al, 1982; Wartlick et al, 2011b).

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