The co-activator CREB-binding protein participates in enhancer-dependent activities of bicoid.
Bicoid (Bcd) is a transcriptional activator required for early embryonic patterning in Drosophila. Despite extensive studies, it currently remains unclear how Bcd activates transcription and what proteins participate in its activation process. In this report, we describe experiments to analyze the role of the Drosophila co-activator dCBP in Bcd-mediated activation. In Drosophila S2 cells, the Bcd activity is increased by the co-transfection of plasmids expressing dCBP and reduced by double-stranded RNA-mediated interference against dCBP. We further show that Bcd and dCBP can interact with each other and that Bcd-interacting domains of dCBP can cause dominant negative effects on Bcd activity in S2 cells. Our comparison of two Bcd-responsive enhancers, hunchback (hb) and knirps (kni), reveals a differential role of dCBP in facilitating Bcd activation. A dCBP mutant defective in its histone acetyltransferase activity exhibits a reduced, but not abolished, co-activator function for Bcd. Our chromatin immunoprecipitation experiments show that dCBP can increase not only the occupancy of Bcd itself at the enhancers but also the recruitment of general transcription factors to the promoter. Together, these experiments suggest that dCBP is an enhancer-dependent co-activator of Bcd, facilitating its activation through multiple mechanisms.
Fu
Dechen
D
Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, Graduate Program in Molecular and Developmental Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA.
Wen
Ying
Y
Ma
Jun
J
D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D050882:CREB-Binding Protein; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry; D047369:Chromatin Immunoprecipitation; D004305:Dose-Response Relationship, Drug; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D004742:Enhancer Elements, Genetic; D005799:Genes, Dominant; D005982:Glutathione Transferase / Q000378:metabolism; D051548:Histone Acetyltransferases; D018398:Homeodomain Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D002843:Chromatin; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators; C056478:bcd protein, Drosophila; D000123:Acetyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D050882:CREB-Binding Protein; D051548:Histone Acetyltransferases; D005982:Glutathione Transferase