Transcriptional regulation of the Drosophila homeotic gene teashirt by the homeodomain protein Fushi tarazu.
The Drosophila melanogaster gene teashirt (tsh) is essential for segment identity of the embryonic thorax and abdomen. A deletion 3' to the tsh transcription unit causes the loss of tsh early expression in the even-numbered parasegments, and the corresponding larval cuticular patterns are disrupted. tsh function in the odd-numbered parasegments in these mutants is normal by both criteria. The in vivo activities of genomic fragments from the deleted region were tested in transgenic embryos. A 2.0 kb enhancer from the 3' region acts mainly in the even-numbered parasegments and is dependent on fushi tarazu (ftz) activity, which encodes a homeodomain protein required for the development of even-numbered parasegments. Ftz protein binds in vitro to four distinct sequences in a 220 bp sub-fragment; these and neighboring sequences are conserved in the equivalent enhancer isolated from Drosophila virilis. Tsh protein produced under the control of the 220 bp enhancer partially rescues a null tsh mutation, with its strongest effect in the even-numbered parasegments. Mutation of the Ftz binding sites partially abrogates the capacity for rescue. These results suggest a composite mechanism for regulation of tsh, with different activators such as ftz contributing to the overall pattern of expression of this key regulator.
Coré
N
N
Laboratoire de Génétique et Physiologie du Développement, UMR 9943 C.N.R.S.-Université, I.B.D.M. CNRS-INSERM-Université de la Méditerranée, Marseille, France.
Charroux
B
B
McCormick
A
A
Vola
C
C
Fasano
L
L
Scott
M P
MP
Kerridge
S
S
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian; D004742:Enhancer Elements, Genetic; D051717:Fushi Tarazu Transcription Factors; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C497169:ftz protein, Drosophila; C066830:tsh protein, Drosophila