TEF-1 transcription factors regulate activity of the mouse mammary tumor virus LTR.

Abstract	The mouse mammary tumor virus long terminal repeat (LTR) is a potent transcriptional enhancer. We identified several putative binding sites for the TEF-1 family of transcription factors (TEF-1, RTEF-1, DTEF-1, and ETF) in the proximal negative regulatory element of the LTR. Gel mobility shift assays revealed strong TEF-1 factor binding to one site using nuclear extracts from CV-1 cells and from the human breast cancer cell line MCF-7. Mutation of this site increased basal activity of the LTR. In transient transfection assays, TEF-1 squelched the basal LTR activity and completely abrogated the response to the glucocorticoid dexamethasone. RTEF-1 and DTEF-1 had little effect on the basal activity, whereas ETF activated the LTR. These TEF-1 factors also interfered with the response to dexamethasone. Taken together, our results reveal an important new role for TEF-1 factors in regulating MMTV LTR activity and suggest that TEF-1 factors might participate in mammary tumorigenesis.
Authors	Tomoji Maeda, Mamiko Maeda, Alexandre F R Stewart
Journal	Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 296 Issue 5 Pg. 1279-85 (Sep 06 2002) ISSN: 0006-291X [Print] United States
PMID	12207913 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References	DNA-Binding Proteins DTEF-1 protein, Gallus gallus Glucocorticoids Muscle Proteins Nuclear Proteins TEA Domain Transcription Factors TEAD1 protein, human TEAD4 protein, human Tead3 protein, mouse Trans-Activators Transcription Factors Dexamethasone
Topics	Base Sequence Binding Sites Cell Line DNA-Binding Proteins (physiology) Dexamethasone (antagonists & inhibitors) Gene Expression Regulation, Viral Glucocorticoids (antagonists & inhibitors) Humans Mammary Tumor Virus, Mouse (genetics) Molecular Sequence Data Muscle Proteins (physiology) Nuclear Proteins Promoter Regions, Genetic TEA Domain Transcription Factors Terminal Repeat Sequences Trans-Activators (physiology) Transcription Factors (physiology) Transcription, Genetic Tumor Cells, Cultured

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