Physical interaction between GATA-5 and hepatocyte nuclear factor-1alpha results in synergistic activation of the human lactase-phlorizin hydrolase promoter.
GATA-4, -5, and -6 zinc finger and hepatocyte nuclear factor-1alpha (HNF-1alpha) homeodomain transcription factors are expressed in the intestinal epithelium and synergistically activate the promoter of intestinal genes. Here, we demonstrate that GATA-5 and HNF-1alpha physically associate both in vivo and in vitro and that this interaction is necessary for cooperative activation of the lactase-phlorizin hydrolase promoter. Furthermore, physical association is mediated by the C-terminal zinc finger of GATA factors and the homeodomain of HNF-1alpha. Deletion of HNF-1alpha activation domains or interruption of HNF-1-binding sites in the lactase-phlorizin hydrolase promoter resulted in a complete loss of cooperativity, whereas deletion of GATA-5 activation domains or interruption of GATA-binding sites resulted in a reduction, but not an elimination, of cooperativity. We hypothesize that GATA/HNF-1alpha cooperativity is mediated by HNF-1alpha through its activation domains, which are oriented for high levels of activation through binding to DNA and physical association with GATA factors. These data suggest a paradigm whereby intestine-specific gene expression is regulated by unique interactions among tissue-restricted transcription factors coexpressed in the intestine. Parallel mechanisms in other tissues as well as in Drosophila suggest that zinc finger/homeodomain interactions are an efficient pathway of cooperative activation of gene transcription that has been conserved throughout evolution.
van Wering
Herbert M
HM
Division of Gastroenterology and Nutrition, Department of Medicine, Children's Hospital, Boston, Massachusetts 02115, USA.
Huibregtse
Inge L
IL
van der Zwan
Sanne M
SM
de Bie
Maartje S
MS
Dowling
Lauren N
LN
Boudreau
Francois
F
Rings
Edmond H H M
EH
Grand
Richard J
RJ
Krasinski
Stephen D
SD
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050992:GATA5 Transcription Factor; D005822:Genetic Vectors; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D010694:Lactase-Phlorizin Hydrolase / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D050992:GATA5 Transcription Factor; C494755:GATA5 protein, human; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D010694:Lactase-Phlorizin Hydrolase