Dual function of a nuclear factor I binding site in MMTV transcription regulation

• Published in: Nucleic acids research 1989-04, Vol.17 (8), p.3065-3078
• Main Authors: BUETTI, E, KÜHNEL, B, DIGGELMANN, H
• Format: Article
• Language: English
• Subjects: Animals; Binding Sites; Biological and medical sciences; CCAAT-Enhancer-Binding Proteins; Dexamethasone - pharmacology; DNA Mutational Analysis; DNA-Binding Proteins - physiology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; L Cells (Cell Line); Mammary Tumor Virus, Mouse - genetics; Mice; Molecular and cellular biology; Molecular genetics; Mouse mammary tumor virus; NFI Transcription Factors; Nuclear Proteins - physiology; Promoter Regions, Genetic; Receptors, Glucocorticoid - physiology; Regulatory Sequences, Nucleic Acid; Transcription Factors - physiology; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing; Y-Box-Binding Protein 1
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/17.8.3065

Using linker-scanning mutagenesis we had previously identified four elements within the MMTV LTR which are necessary for transcriptional stimulation by glucocorticoid hormones. Two of them overlapped with regions to which the glucocorticoid receptor binds in vitro. The third element contained a NF-I binding site, and the fourth the TATA box. Here we show that mutations that abolish in vitro binding of NF-I had a negative effect also on the basal activity of the MMTV promoter of LTR-containing plasmids stably integrated in Ltk- fibroblasts. The analysis of double mutants altered in the NF-I plus either one of the receptor binding elements further demonstrated that the NF-I site functionally cooperated with the proximal (-120) element, which alone was extremely inefficient in stimulation. The stronger distal (-181/-172) element was independent of NF-I and showed functional cooperativity with the proximal hormone-binding element.