Regulation of scute function by extramacrochaete in vitro and in vivo.
The pattern of adult sensilla in Drosophila is established by the dosage-sensitive interaction of two antagonistic groups of genes. Sensilla development is promoted by members of the achaete-scute complex and the daughterless gene whereas it is suppressed by whereas extramacrochaete (emc) and hairy. All these genes encode helix-loop-helix proteins. The products of the achaete-scute complex and daughterless interact to form heterodimers able to activate transcription. In this report, we show that (1) extra-macrochaete forms heterodimers with the achaete, scute, lethal of scute and daughterless products; (2) extramacrochaete inhibits DNA-binding of Achaete, Scute and Lethal of Scute/Daughterless heterodimers and Daughterless homodimers and (3) extramacrochaete inhibits transcription activation by heterodimers in a yeast assay system. In addition, we have studied the expression patterns of scute in wild-type and extramacrochaete mutant imaginal discs. Expression of scute RNA during imaginal development occurs in groups of cells, but high levels of protein accumulate in the nuclei of only a subset of the RNA-expressing cells. The pattern is dynamic and results in a small number of protein-containing cells that correspond to sensillum precursors. extramacrochaete loss-of-function alleles develop extra sensilla and correspondingly display a larger number of cells with scute protein. These cells appear to arise from those that in the wild type already express scute RNA; hence, extramacrochaete is a repressor of scute function whose action may take place post-transcriptionally.
Cabrera
C V
CV
Marie Curie Research Institute, Oxted, UK.
Alonso
M C
MC
Huikeshoven
H
H
D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D018604:Epitope Mapping; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D012679:Sense Organs / Q000196:embryology*