The transcription factor HNF1 acts with C/EBP alpha to synergistically activate the human albumin promoter through a novel domain.
HNF1 and C/EBP alpha are transcription factors that bind to and trans-activate the human albumin gene proximal promoter. Various 5' deletions of the human albumin promoter were coupled to a luciferase reporter gene (alb-luc constructs) and co-electroporated with HNF1 and/or C/EBP alpha expression vectors into HeLa cells. Luciferase activities from co-electroporation of the HNF1 and C/EBP alpha expression vectors with the alb-luc constructs were approximately 10-fold greater than the sum of the activities achieved with HNF1 and C/EBP alpha alone. Analysis of COOH-terminal or internal deletions of the HNF1 expression vector revealed that the domain important for collaborative interaction with C/EBP alpha could be localized to a 157 amino acid region not previously described. This domain is proline and glutamine-rich and is highly homologous (66%) to a portion of vHNF1, an evolutionarily related gene first identified in dedifferentiated hepatoma cells. A construct linking the negatively charged activation domain of herpes simplex virus protein VP16 to the DNA-binding domain of HNF1 showed that it could also synergize with C/EBP alpha to trans-activate the human albumin gene promoter. Our studies delineate a domain in HNF1 important for synergistic activation with C/EBP alpha.
Wu
K J
KJ
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Wilson
D R
DR
Shih
C
C
Darlington
G J
GJ
D000418:Albumins / Q000235:genetics*; D000595:Amino Acid Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000502:physiology*; D004357:Drug Synergism; D005786:Gene Expression Regulation; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D017405:Herpes Simplex Virus Protein Vmw65 / Q000502:physiology; D006801:Humans; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D000418:Albumins; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D017405:Herpes Simplex Virus Protein Vmw65; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta