Cooperative interaction between hepatocyte nuclear factor 4 alpha and GATA transcription factors regulates ATP-binding cassette sterol transporters ABCG5 and ABCG8.
Cholesterol homeostasis is maintained by coordinate regulation of cholesterol synthesis and its conversion to bile acids in the liver. The excretion of cholesterol from liver and intestine is regulated by ATP-binding cassette half-transporters ABCG5 and ABCG8. The genes for these two proteins are closely linked and divergently transcribed from a common intergenic promoter region. Here, we identified a binding site for hepatocyte nuclear factor 4alpha (HNF4alpha) in the ABCG5/ABCG8 intergenic promoter, through which HNF4alpha strongly activated the expression of a reporter gene in both directions. The HNF4alpha-responsive element is flanked by two conserved GATA boxes that were also required for stimulation by HNF4alpha. GATA4 and GATA6 bind to the GATA boxes, coexpression of GATA4 and HNF4alpha leads to a striking synergistic activation of both the ABCG5 and the ABCG8 promoters, and binding sites for HNF4alpha and GATA were essential for maximal synergism. We also show that HNF4alpha, GATA4, and GATA6 colocalize in the nuclei of HepG2 cells and that a physical interaction between HNF4alpha and GATA4 is critical for the synergistic response. This is the first demonstration that HNF4alpha acts synergistically with GATA factors to activate gene expression in a bidirectional fashion.
Sumi
Koichi
K
Laboratory of Systems Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, Japan.
Tanaka
Toshiya
T
Uchida
Aoi
A
Magoori
Kenta
K
Urashima
Yasuyo
Y
Ohashi
Riuko
R
Ohguchi
Hiroto
H
Okamura
Masashi
M
Kudo
Hiromi
H
Daigo
Kenji
K
Maejima
Takashi
T
Kojima
Noriaki
N
Sakakibara
Iori
I
Jiang
Shuying
S
Hasegawa
Go
G
Kim
Insook
I
Osborne
Timothy F
TF
Naito
Makoto
M
Gonzalez
Frank J
FJ
Hamakubo
Takao
T
Kodama
Tatsuhiko
T
Sakai
Juro
J
D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000256:Adenoviridae / Q000235:genetics; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D016384:Consensus Sequence; D017124:Conserved Sequence; D050991:GATA4 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050993:GATA6 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D017930:Genes, Reporter; D051557:Hepatocyte Nuclear Factor 4 / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
C416945:ABCG5 protein, human; C416946:ABCG8 protein, human; D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters; D050991:GATA4 Transcription Factor; D050993:GATA6 Transcription Factor; D051557:Hepatocyte Nuclear Factor 4; D008074:Lipoproteins; D008156:Luciferases