TY - JOUR
T1 - A binding site for multiple transcriptional activators in the fushi tarazu proximal enhancer is essential for gene expression in vivo
AU - Han, Wei
AU - Yu, Yan
AU - Su, Kai
AU - Kohanski, Ronald A.
AU - Pick, Leslie
PY - 1998/6
Y1 - 1998/6
N2 - The Drosophila homeobox gene fushi tarazu (ftz) is expressed in a highly dynamic striped pattern in early embryos. A key regulatory element that controls the ftz pattern is the ftz proximal enhancer, which mediates positive autoregulation via multiple binding sites for the Ftz protein. In addition, the enhancer is necessary for stripe establishment prior to the onset of autoregulation. We previously identified nine binding sites for multiple Drosophila nuclear proteins in a core 323-bp region of the enhancer. Three of these nine sites interact with the same cohort of nuclear prOteins in vitro. We showed previously that the nuclear receptor Ftz-F1 interacts with this repeated module. Here we purified additional proteins interacting with this module from Drosophila nuclear extracts. Peptide sequences of the zinc finger protein Ttk and the transcription factor Adf-1 were obtained. While Ttk is thought to be a repressor of ftz stripes, we have shown that both Adf-1 and Ftz-F1 activate transcription in a binding site-dependent fashion. These two-proteins are expressed ubiquitously at the time ftz is expressed in strips, suggesting that either may activate striped expression alone or in combination with the Ftz protein. The roles of the nine nuclear factor binding sites were tested in vivo, by site-directed mutagenesis of individual and multiple sites. The three Ftz-F1-Adf-1-Ttk binding sites were found to be functionally redundant and essential for stripe expression in transgenic embryos. Thus, a biochemical analysis identified cis-acting regulatory modules that are required for gene expression in vivo. The finding of repeated binding sites for multiple nuclear proteins underscores the high degree of redundancy built into embryonic gene regulatory networks.
AB - The Drosophila homeobox gene fushi tarazu (ftz) is expressed in a highly dynamic striped pattern in early embryos. A key regulatory element that controls the ftz pattern is the ftz proximal enhancer, which mediates positive autoregulation via multiple binding sites for the Ftz protein. In addition, the enhancer is necessary for stripe establishment prior to the onset of autoregulation. We previously identified nine binding sites for multiple Drosophila nuclear proteins in a core 323-bp region of the enhancer. Three of these nine sites interact with the same cohort of nuclear prOteins in vitro. We showed previously that the nuclear receptor Ftz-F1 interacts with this repeated module. Here we purified additional proteins interacting with this module from Drosophila nuclear extracts. Peptide sequences of the zinc finger protein Ttk and the transcription factor Adf-1 were obtained. While Ttk is thought to be a repressor of ftz stripes, we have shown that both Adf-1 and Ftz-F1 activate transcription in a binding site-dependent fashion. These two-proteins are expressed ubiquitously at the time ftz is expressed in strips, suggesting that either may activate striped expression alone or in combination with the Ftz protein. The roles of the nine nuclear factor binding sites were tested in vivo, by site-directed mutagenesis of individual and multiple sites. The three Ftz-F1-Adf-1-Ttk binding sites were found to be functionally redundant and essential for stripe expression in transgenic embryos. Thus, a biochemical analysis identified cis-acting regulatory modules that are required for gene expression in vivo. The finding of repeated binding sites for multiple nuclear proteins underscores the high degree of redundancy built into embryonic gene regulatory networks.
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U2 - 10.1128/mcb.18.6.3384
DO - 10.1128/mcb.18.6.3384
M3 - Article
C2 - 9584179
AN - SCOPUS:0031846738
SN - 0270-7306
VL - 18
SP - 3384
EP - 3394
JO - Molecular and cellular biology
JF - Molecular and cellular biology
IS - 6
ER -