Overexpression of the m4 and malpha genes of the E(spl)-complex antagonizes notch mediated lateral inhibition.
Intercellular signalling mediated by Notch proteins is crucial to many cell fate decisions in metazoans. Its profound effects on cell fate and proliferation require that a complex set of responses involving positive and negative signal transducers be orchestrated around each instance of signalling. In Drosophila the basic-helix-loop-helix (bHLH) repressor encoding genes of the E(spl) locus are induced by Notch signalling and mediate some of its effects, such as suppression of neural fate. Here we report on a novel family of Notch responsive genes, whose products appear to act as antagonists of the Notch signal in the process of adult sensory organ precursor singularization. They, too, reside in the E(spl) locus and comprise transcription units E(spl) m4 and E(spl) malpha. Overexpression of these genes causes downregulation of E(spl) bHLH expression accompanied by cell autonomous overcommitment of sensory organ precursors and tufting of bristles. Interestingly, negative regulation of the Notch pathway by overexpression of E(spl) m4 and malpha is specific to the process of sensory organ precursor singularization and does not impinge on other instances of Notch signalling.
Apidianakis
Y
Y
Institute of Molecular Biology and Biotechnology, FORTH and Department of Biology, University of Crete, Box 1527, Heraklion GR-71 110, Greece.
Nagel
A C
AC
Chalkiadaki
A
A
Preiss
A
A
Delidakis
C
C
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D051792:Basic Helix-Loop-Helix Proteins; D002490:Central Nervous System / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D051880:Receptors, Notch; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012679:Sense Organs / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors; D014158:Transcription, Genetic
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch; D012097:Repressor Proteins; D014157:Transcription Factors; C121961:E(spl)m4-BFM protein, Drosophila; C121960:E(spl)m7-HLH protein, Drosophila; C084530:E(spl)mdelta-HLH protein, Drosophila; C497759:N protein, Drosophila