Abstract
Patterning of multicellular fields requires mechanisms to coordinate developmental decisions made by populations of cells. Evidence is accumulating that the necessary information is provided by localized sources of secreted signalling proteins which act as morphogens. We review evidence that Wingless, Dpp and Hedgehog proteins act as morphogens in the developing wing of Drosophila and discuss recent work illustrating that signalling helps to shape their activity gradients by regulating ligand distribution and by modulating the responsiveness of target cells. These studies suggest that there is more to being a morphogen than formation of a ligand gradient by passive diffusion.
MeSH terms
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Animals
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Biological Transport, Active
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Body Patterning / physiology*
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Diffusion
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Drosophila / embryology*
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Drosophila Proteins*
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Hedgehog Proteins
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Insect Proteins / antagonists & inhibitors
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Insect Proteins / metabolism
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Insect Proteins / physiology
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Ligands
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Membrane Proteins / physiology
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Proteoglycans / metabolism
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins / physiology
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Signal Transduction / physiology
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Wings, Animal / embryology*
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Wings, Animal / metabolism*
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Wnt1 Protein
Substances
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Drosophila Proteins
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Hedgehog Proteins
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Insect Proteins
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Ligands
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Membrane Proteins
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Proteoglycans
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Proto-Oncogene Proteins
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Wnt1 Protein
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dpp protein, Drosophila
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por protein, Drosophila
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wg protein, Drosophila
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hh protein, Drosophila