Hedgehog signaling in the Drosophila eye and head: an analysis of the effects of different patched trans-heterozygotes.
Characterization of different alleles of the Hedgehog receptor patched (ptc) indicates that they can be grouped into several classes. Most mutations result in complete loss of Ptc function. However, missense mutations located within the putative sterol-sensing domain (SSD) or C terminus of ptc encode antimorphic proteins that are unable to repress Smo activity and inhibit wild-type Ptc from doing so, but retain the ability to bind and sequester Hh. Analysis of the eye and head phenotypes of Drosophila melanogaster in various ptc/ptc(tuf1) heteroallelic combinations shows that these two classes of ptc allele can be easily distinguished by their eye phenotype, but not by their head phenotype. Adult eye size is inversely correlated with head vertex size, suggesting an alteration of cell fate within the eye-antennal disc. A balance between excess cell division and cell death in the mutant eye discs may also contribute to final eye size. In addition, contrary to results reported recently, the role of Hh signaling in the Drosophila head vertex appears to be primarily in patterning rather than in proliferation, with Ptc and Smo having opposing effects on formation of medial structures.
Thomas
Chloe
C
MRC Intercellular Signalling Group, Centre for Developmental Genetics, University of Sheffield, Sheffield S10 2TN, United Kingdom.
Ingham
Philip W
PW
D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics*; D016923:Cell Death; D002455:Cell Division; D003433:Crosses, Genetic; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005123:Eye / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D006257:Head / Q000254:growth & development / Q000502:physiology*; D053823:Hedgehog Proteins; D006579:Heterozygote; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D010641:Phenotype; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D000072086:Smoothened Receptor
D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D012097:Repressor Proteins; D000072086:Smoothened Receptor; C070844:ptc protein, Drosophila; C100664:smo protein, Drosophila; C077245:hh protein, Drosophila