scratch, a pan-neural gene encoding a zinc finger protein related to snail, promotes neuronal development.
The Drosophila scratch (scrt) gene is expressed in most or all neuronal precursor cells and encodes a predicted zinc finger transcription factor closely related to the product of the mesoderm determination gene snail (sna). Adult flies homozygous for scrt null alleles have a reduced number of photoreceptors in the eye, and embryos lacking the function of both scrt and the pan-neural gene deadpan (dpn), which encodes a basic helix-loop-helix (bHLH) protein, exhibit a significant loss of neurons. Conversely, ectopic expression of a scrt transgene during embryonic and adult development leads to the production of supernumerary neurons. Consistent with scrt functioning as a transcription factor, various genes are more broadly expressed than normal in scrt null mutants. Reciprocally, these same genes are expressed at reduced levels in response to ectopic scrt expression. We propose that scrt promotes neuronal cell fates by suppressing expression of genes promoting non-neuronal cell fates. We discuss the similarities between the roles of the ancestrally related scrt, sna, and escargot (esc) genes in regulating cell fate choices.
Roark
M
M
Biological Sciences Program, California State University, San Marcos 92096, USA.
Sturtevant
M A
MA
Emery
J
J
Vaessin
H
H
Grell
E
E
Bier
E
E
D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D017403:In Situ Hybridization; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics; D016335:Zinc Fingers / Q000235:genetics*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C096141:scrt protein, Drosophila; C000604451:sna protein, Drosophila