The COE transcription factor Collier is a mediator of short-range Hedgehog-induced patterning of the Drosophila wing

BACKGROUND The secreted Hedgehog (Hh) proteins have been implicated as mediators of positional information in vertebrates and invertebrates. A gradient of Hh activity contributes to antero-posterior (A/P) patterning of the fly wing. In addition to inducing localised expression of Decapentaplegic (Dpp), which in turn relays patterning cues at long range, Hh directly patterns the central region of the wing. RESULTS We show that short-range, dose-dependent Hh activity is mediated by activation of the transcription factor Collier (Col). In the absence of col activity, longitudinal veins 3 and 4 (L3 and L4) are apposed and the central intervein is missing. Hh expression induces col expression in a narrow stripe of cells along the A/P boundary through a dual-input mechanism: inhibition of proteolysis of Cubitus-interruptus (Ci) and activation of the Fused (Fu) kinase. Col, in cooperation with Ci, controls the formation of the central intervein by activating the expression of blistered (bs), which encodes the Drosophila serum response factor (D-SRF), the activity of which is required for the adoption and maintenance of the intervein cell fate. Furthermore, col is allelic to knot, a gene involved in the formation of the central part of the wing. This finding completes our understanding of the sectorial organisation of the Drosophila wing. CONCLUSIONS Col, the Drosophila member of the COE family (Col/Olf-1/EBF) of non-basic, helix-loop-helix (HLH)-containing transcription factors, is a mediator of the short-range organising activity of Hh in the Drosophila wing. Our results support the idea that Hh controls target gene expression in a concentration-dependent manner and highlight the importance of the Fu kinase in this differential regulation. The high degree of evolutionary conservation of the COE proteins and the diversity of developmental processes controlled by Hh signalling raises the possibility that the specific genetic interactions depicted here may also operate in vertebrates.

[1]  P. Ingham,et al.  Transcriptional activation of hedgehog target genes in Drosophila is mediated directly by the cubitus interruptus protein, a member of the GLI family of zinc finger DNA-binding proteins. , 1996, Genes & development.

[2]  T. Tabata,et al.  Hedgehog is a signaling protein with a key role in patterning Drosophila imaginal discs , 1994, Cell.

[3]  B. Biehs,et al.  Boundaries in the Drosophila wing imaginal disc organize vein-specific genetic programs. , 1998, Development.

[4]  D. Kalderon,et al.  Hedgehog stimulates maturation of Cubitus interruptus into a labile transcriptional activator , 1998, Nature.

[5]  A. Vincent,et al.  collier, a novel regulator of Drosophila head development, is expressed in a single mitotic domain , 1996, Current Biology.

[6]  G. Struhl,et al.  In vivo evidence that Patched and Smoothened constitute distinct binding and transducing components of a Hedgehog receptor complex. , 1998, Development.

[7]  P. Lawrence,et al.  Hedgehog acts by distinct gradient and signal relay mechanisms to organise cell type and cell polarity in the Drosophila abdomen. , 1997, Development.

[8]  K. Moses,et al.  The segment polarity gene hedgehog is required for progression of the morphogenetic furrow in the developing Drosophila eye , 1993, Cell.

[9]  S. Blair,et al.  Engrailed expression in the anterior lineage compartment of the developing wing blade of Drosophila. , 1992, Development.

[10]  A. Hidalgo.  Three distinct roles for the engrailed gene in Drosophila wing development , 1994, Current Biology.

[11]  P. Lawrence,et al.  Hedgehog organises the pattern and polarity of epidermal cells in the Drosophila abdomen. , 1997, Development.

[12]  H. Tricoire,et al.  Modulation of Hedgehog target gene expression by the Fused serine–threonine kinase in wing imaginal discs , 1998, Mechanisms of Development.

[13]  T. Préat.  Characterization of Suppressor of fused, a complete suppressor of the fused segment polarity gene of Drosophila melanogaster. , 1992, Genetics.

[14]  P. Ingham,et al.  smoothened encodes a receptor-like serpentine protein required for hedgehog signalling , 1996, Nature.

[15]  I. Guerrero,et al.  Targeted expression of the signaling molecule decapentaplegic induces pattern duplications and growth alterations in Drosophila wings. , 1994, The EMBO journal.

[16]  G. Struhl,et al.  Protein kinase A and hedgehog signaling in drosophila limb development , 1995, Cell.

[17]  D. Slusarski,et al.  Mutations that alter the timing and pattern of cubitus interruptus gene expression in Drosophila melanogaster. , 1995, Genetics.

[18]  T. Jessell,et al.  Pax6 Controls Progenitor Cell Identity and Neuronal Fate in Response to Graded Shh Signaling , 1997, Cell.

[19]  M. Tessier-Lavigne,et al.  Long-range sclerotome induction by sonic hedgehog: Direct role of the amino-terminal cleavage product and modulation by the cyclic AMP signaling pathway , 1995, Cell.

[20]  A. Ghysen,et al.  Genetic basis of the formation and identity of type I and type II neurons in Drosophila embryos. , 1997, Development.

[21]  M. Krasnow,et al.  The Drosophila Serum Response Factor gene is required for the formation of intervein tissue of the wing and is allelic to blistered. , 1996, Development.

[22]  M. Strigini,et al.  A Hedgehog activity gradient contributes to AP axial patterning of the Drosophila wing. , 1997, Development.

[23]  T. Kornberg,et al.  Proteolysis That Is Inhibited by Hedgehog Targets Cubitus interruptus Protein to the Nucleus and Converts It to a Repressor , 1997, Cell.

[24]  E. Bier,et al.  The Drosophila rhomboid gene mediates the localized formation of wing veins and interacts genetically with components of the EGF-R signaling pathway. , 1993, Genes & development.

[25]  Konrad Basler,et al.  Hedgehog Controls Limb Development by Regulating the Activities of Distinct Transcriptional Activator and Repressor Forms of Cubitus interruptus , 1999, Cell.

[26]  A. Vincent,et al.  Requirement for the Drosophila COE transcription factor Collier in formation of an embryonic muscle: transcriptional response to notch signalling. , 1999, Development.

[27]  J. Mullor,et al.  Hedgehog activity, independent of decapentaplegic, participates in wing disc patterning. , 1997, Development.

[28]  G. Struhl,et al.  Dual Roles for Patched in Sequestering and Transducing Hedgehog , 1996, Cell.

[29]  D. Kalderon,et al.  Hedgehog signalling: Ci complex cuts and clasps , 1997, Current Biology.

[30]  R. Brewster,et al.  Gli/Zic factors pattern the neural plate by defining domains of cell differentiation , 1998, Nature.

[31]  T. Préat,et al.  A putative serine/threonine protein kinase encoded by the segment-polarity fused gene of Drosophila , 1990, Nature.

[32]  R. Goodman,et al.  Protein kinase A directly regulates the activity and proteolysis of cubitus interruptus. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[33]  T. Kornberg,et al.  Analysis of cubitus interruptus regulation in Drosophila embryos and imaginal disks. , 1995, Development.

[34]  C. Tabin,et al.  Biochemical evidence that Patched is the Hedgehog receptor , 1996, Nature.

[35]  M. Noll,et al.  The Drosophila smoothened Gene Encodes a Seven-Pass Membrane Protein, a Putative Receptor for the Hedgehog Signal , 1996, Cell.

[36]  Isabel Guerrero,et al.  The fu gene discriminates between pathways to control dpp expression in Drosophila imaginal discs , 1996, Mechanisms of Development.

[37]  A. Vincent,et al.  XCoe2, a transcription factor of the Col/Olf-1/EBF family involved in the specification of primary neurons in Xenopus , 1998, Current Biology.

[38]  A. Garcı́a-Bellido,et al.  Notch signalling regulates veinlet expression and establishes boundaries between veins and interveins in the Drosophila wing. , 1997, Development.

[39]  A. Garcı́a-Bellido,et al.  Genetic interactions and cell behaviour in blistered mutants during proliferation and differentiation of the Drosophila wing. , 1998, Development.

[40]  J. Mohler,et al.  Role of knot (kn) in wing patterning in Drosophila. , 1997, Genetics.

[41]  T. Jessell,et al.  Floor plate and motor neuron induction by different concentrations of the amino-terminal cleavage product of sonic hedgehog autoproteolysis , 1995, Cell.

[42]  Mary Ellen Lane,et al.  Function of protein kinase A in hedgehog signal transduction and Drosophila imaginal disc development , 1995, Cell.

[43]  J. Modolell,et al.  araucan and caupolican provide a link between compartment subdivisions and patterning of sensory organs and veins in the Drosophila wing. , 1996, Genes & development.

[44]  Q. T. Wang,et al.  Drosophila cubitus interruptus forms a negative feedback loop with patched and regulates expression of Hedgehog target genes. , 1997, Development.

[45]  Konrad Basler,et al.  Compartment boundaries and the control of Drosopfiffa limb pattern by hedgehog protein , 1994, Nature.

[46]  M. Scott,et al.  The tumour-suppressor gene patched encodes a candidate receptor for Sonic hedgehog , 1996, Nature.

[47]  T. Tabata,et al.  The Drosophila hedgehog gene is expressed specifically in posterior compartment cells and is a target of engrailed regulation. , 1992, Genes & development.

[48]  P. Ingham,et al.  The Drosophila segment polarity gene patched is involved in a position-signalling mechanism in imaginal discs. , 1990, Development.

[49]  S. Eaton,et al.  Blistered: a gene required for vein/intervein formation in wings of Drosophila. , 1994, Development.