title: Forces shaping a Hox morphogenetic gene network.
abstract: The Abdominal-B selector protein induces organogenesis of the posterior spiracles by coordinating an organ-specific gene network. The complexity of this network begs the questions of how it originated and what selective pressures drove its formation. Given that the network likely formed in a piecemeal fashion, with elements recruited sequentially, we studied the consequences of expressing individual effectors of this network in naive epithelial cells. We found that, with exception of the Crossveinless-c (Cv-c) Rho GTPase-activating protein, most effectors exert little morphogenetic effect by themselves. In contrast, Cv-c expression causes cell motility and down-regulates epithelial polarity and cell adhesion proteins. These effects differ in cells endogenously expressing Cv-c, which have acquired compensatory mechanisms. In spiracle cells, the down-regulation of polarity and E-cadherin expression caused by Cv-c-induced Rho1 inactivation are compensated for by the simultaneous spiracle up-regulation of guanine nucleotide exchange factor (GEF) proteins, cell polarity, and adhesion molecules. Other epithelial cells that have coopted Cv-c to their morphogenetic gene networks are also resistant to Cv-c's deleterious effects. We propose that cooption of a novel morphogenetic regulator to a selector cascade causes cellular instability, resulting in strong selective pressure that leads that same cascade to recruit molecules that compensate it. This experimental-based hypothesis proposes how the frequently observed complex organogenetic gene networks are put together.
authors: Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Universidad Pablo de Olavide, 41013 Seville, Spain.
authors: Sol
authors: S
authors: Sotillos
authors: Mario
authors: M
authors: Aguilar
authors: James Castelli-Gair
authors: JC
authors: Hombría
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000235:genetics; D004331:Drosophila melanogaster; D020690:GTPase-Activating Proteins / Q000096:biosynthesis* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D053263:Gene Regulatory Networks / Q000502:physiology*; D005801:Genes, Homeobox / Q000502:physiology*; D009024:Morphogenesis / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; D020690:GTPase-Activating Proteins; C502709:cv-c protein, Drosophila; C511153:Rho1 protein, Drosophila; D020741:rho GTP-Binding Proteins