Analysis of the transcriptional activation domain of the Drosophila tango bHLH-PAS transcription factor.
Basic-helix-loop-helix-PAS transcription factors play important roles in diverse biological processes including cellular differentiation and specification, oxygen tension regulation and dioxin metabolism. Drosophila tango is orthologous to mammalian Arnt and acts as a common dimerization partner for bHLH-PAS proteins during embryogenesis. A transient transfection assay using Drosophila S2 tissue culture cells and wild-type and mutant Drosophila tango cDNAs was used to localize the activation domain of the Tango protein. An activation domain was identified in the C-terminus of TGO consisting of poly-glutamine and histidine-proline repeats. Transcriptional activation of the fibroblast growth factor receptor (breathless) gene required an intact TGO C-terminus, in vitro. Co-expression assays of trachealess and tgo in the developing eye imaginal disc showed a requirement for the C-terminal transactivation domain of TGO for a cellular response. Genetic analysis of tgo(3) shows that the paired repeat is necessary for tracheal tubule formation in all branches. Lastly, expression of a C-terminal truncated tgo transgene specifically in the CNS midline and trachea resulted in reductions in the number of breathless-expressing cells. These results together identify TGO's transactivation domain and establish its importance for proper target gene regulation and cellular specification.
Sonnenfeld
Margaret J
MJ
Department of Cellular and Molecular Medicine, University of Ottawa, Ontario, Canada K1H 8M5. msonnenf@uottawa.ca
Delvecchio
Christopher
C
Sun
Xuetao
X
D000595:Amino Acid Sequence; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002490:Central Nervous System / Q000196:embryology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D017468:Receptors, Fibroblast Growth Factor; D014157:Transcription Factors; C109766:tgo protein, Drosophila; C099995:trh protein, Drosophila; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; C102301:BTL protein, Drosophila; D011505:Protein-Tyrosine Kinases