title: Action of transcription factors in the control of transferrin receptor expression in human brain endothelium.
abstract: Brain endothelium has a distinctive phenotype, including high expression of transferrin receptor, p-glycoprotein, claudin-5 and occludin. Dermal endothelium expresses lower levels of the transferrin receptor and it is absent from lung endothelium. All three endothelia were screened for transcription factors that bind the transferrin receptor promoter and show different patterns of binding between the endothelia. The transcription factor YY1 has distinct DNA-binding activities in brain endothelium and non-brain endothelium. The target-sites on the transferrin receptor promotor for YY1 lie in close proximity to those of the transcription initiation complex containing TFIID, so the two transcription factors potentially compete or interfere. Notably, the DNA-binding activity of TFIID was the converse of YY1, in different endothelia. YY1 knockdown reduced transferrin receptor expression in brain endothelium, but not in dermal endothelium, implying that YY1 is involved in tissue-specific regulation of the transferrin receptor. Moreover a distinct YY1 variant is present in brain endothelium and it associates with Sp3. A model is presented, in which expression from the transferrin receptor gene in endothelium requires the activity of both TFIID and Sp3, but whether the gene is transcribed in different endothelia, is related to the balance between activating and suppressive forms of YY1.
authors.affiliation: Department of Biological Sciences, The Open University, Milton Keynes MK7 6AA, UK.
authors.forename: Karen
authors.initials: K
authors.lastname: Holloway
authors.forename: Hadassah
authors.initials: H
authors.lastname: Sade
authors.forename: Ignacio A
authors.initials: IA
authors.lastname: Romero
authors.forename: David
authors.initials: D
authors.lastname: Male
mesh_terms: D020029:Base Pairing; D015153:Blotting, Western; D001921:Brain / Q000166:cytology*; D002457:Cell Extracts; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D042783:Endothelial Cells / Q000166:cytology; D004727:Endothelium / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D008168:Lung / Q000166:cytology; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor / Q000378:metabolism; D035362:Transcription Factor TFIID / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D050986:YY1 Transcription Factor / Q000378:metabolism
chemical_list: D002457:Cell Extracts; D020033:Protein Isoforms; D011990:Receptors, Transferrin; D016329:Sp1 Transcription Factor; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D050986:YY1 Transcription Factor; D051705:Sp3 Transcription Factor