DORSAL TWIST INTERACTIONS ESTABLISH SNAIL EXPRESSION IN THE PRESUMPTIVE MESODERM OF THE DROSOPHILA EMBRYO

The first step in the differentiation of the Drosophila mesoderm is the activation of two regulatory genes, twist (twi) and snail (sna), in ventral regions of early embryos. sna is a transcriptional repressor that is uniformly expressed throughout the presumptive mesoderm. Its sharp lateral limits h...

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Bibliographic Details
Published in:Genes & development 1992-08, Vol.6 (8), p.1518-1530
Main Authors: IP, YT, PARK, RE, KOSMAN, D, YAZDANBAKHSH, K, LEVINE, M
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Binding Sites - genetics
Biological and medical sciences
Cell Biology
Cloning, Molecular
Developmental Biology
Drosophila
Drosophila - embryology
Drosophila - genetics
Drosophila Proteins
Fundamental and applied biological sciences. Psychology
Gene expression
Gene Expression Regulation - physiology
Genes, Regulator - genetics
Genetics & Heredity
Larva - genetics
Larva - growth & development
Life Sciences & Biomedicine
Mesoderm - metabolism
Molecular and cellular biology
Molecular genetics
Molecular Sequence Data
Mutagenesis, Site-Directed
Nuclear Proteins - genetics
Nuclear Proteins - metabolism
Phosphoproteins
Plasmids - genetics
Promoter Regions, Genetic - genetics
Recombinant Fusion Proteins - genetics
Repressor Proteins - genetics
Science & Technology
Transcription Factors
Twist-Related Protein 1
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Summary:The first step in the differentiation of the Drosophila mesoderm is the activation of two regulatory genes, twist (twi) and snail (sna), in ventral regions of early embryos. sna is a transcriptional repressor that is uniformly expressed throughout the presumptive mesoderm. Its sharp lateral limits help to establish the boundary between the mesoderm and neuroectoderm. Genetic studies suggest that sna is a target of the dorsal (dl) morphogen, and this interaction provides a model for determining how a morphogen gradient establishes a sharp, on/off threshold response. We present evidence that dl and twi directly activate sna expression. Site-directed mutagenesis of dl- and twi-binding sites within defined regions of the sna promoter suggest that the two proteins (containing the Rel and helix-loop-helix domains, respectively) function multiplicatively to ensure strong, uniform expression of sna, particularly in ventral-lateral regions where there are diminishing amounts of dl. These results are consistent with the possibility that the sharp sna borders are formed by multiplying the shallow dl gradient and the steeper twi gradient.
ISSN:0890-9369
1549-5477
DOI:10.1101/gad.6.8.1518