Wingless promotes proliferative growth in a gradient-independent manner.
Morphogens form concentration gradients that organize patterns of cells and control growth. It has been suggested that, rather than the intensity of morphogen signaling, it is its gradation that is the relevant modulator of cell proliferation. According to this view, the ability of morphogens to regulate growth during development depends on their graded distributions. Here, we describe an experimental test of this model for Wingless, one of the key organizers of wing development in Drosophila. Maximal Wingless signaling suppresses cellular proliferation. In contrast, we found that moderate and uniform amounts of exogenous Wingless, even in the absence of endogenous Wingless, stimulated proliferative growth. Beyond a few cell diameters from the source, Wingless was relatively constant in abundance and thus provided a homogeneous growth-promoting signal. Although morphogen signaling may act in combination with as yet uncharacterized graded growth-promoting pathways, we suggest that the graded nature of morphogen signaling is not required for proliferation, at least in the developing Drosophila wing, during the main period of growth.
Baena-Lopez
Luis Alberto
LA
Department of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
Franch-Marro
Xavier
X
Vincent
Jean-Paul
JP
D019943:Amino Acid Substitution; D000818:Animals; D049109:Cell Proliferation; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D009154:Mutation; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014921:Wings, Animal / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D029721:Drosophila Proteins; D051155:Wnt1 Protein; C074622:wg protein, Drosophila