The E-cadherin promoter: functional analysis of a G.C-rich region and an epithelial cell-specific palindromic regulatory element

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 24; pp. 11495 - 11499
• Main Authors: BEHRENS, J, LOWRICK, O, KLEIN-HITPASS, L, BIRCHMEIER, W
• Format: Journal Article
• Language: English
• Published: Washington, DC National Acad Sciences 15.12.1991; National Academy of Sciences of the United States of America
• Subjects: Animals; Base Sequence; Binding Sites; Biological and medical sciences; Cadherins - genetics; Cell Line; Cell Nucleus - physiology; Deoxyribonuclease I; Epithelium - physiology; Fundamental and applied biological sciences. Psychology; Genomic Library; Humans; Mice; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Oligodeoxyribonucleotides; Promoter Regions, Genetic; Regulatory Sequences, Nucleic Acid; Restriction Mapping; RNA, Messenger - genetics; Transcription, Genetic; Epithelial cell; Tumor; Regulation(control); Cell differentiation; Gene expression; Adhesion
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.24.11495

The cell-cell adhesion molecule E-cadherin is specifically expressed in epithelia and is involved in the maintenance of the epithelial phenotype. Expression of E-cadherin is downregulated in many poorly differentiated carcinomas, which leads to higher motility and invasiveness of the cells. To examine the mechanisms that regulate tissue-specific expression, we have characterized the promoter of the E-cadherin gene. We found that an upstream fragment (positions -178 to +92) mediates strong expression of a chloramphenicol acetyltransferase reporter gene in epithelial cells (i.e., 60% of the level obtained with simian virus 40 promoter/enhancer constructs), whereas in nonepithelial cells this promoter was either inactive or much less active. By DNase I footprinting and gel retardation analysis as well as through functional dissection of the regulatory sequences, we identified two regions that contribute to tissue-specific activity of the promoter: (i) a G-C-rich region between -25 and -58 that generates basic epithelial promoter activity, most likely in combination with an "initiator" element present at the single transcription start site of the gene, and (ii) a palindromic sequence between -75 and -86 (named E-pal) that potentiates the activity of the proximal E-cadherin promoter and confers epithelial cell-specific activity on a simian virus 40 promoter. The E-pal sequence is homologous to cis regulatory elements active in keratin gene promoters and competes with these elements for nuclear factor binding. Interestingly, the activity of the E-cadherin promoter was reduced in dedifferentiated breast carcinoma cells, indicating that the identified elements are subject to negative regulation during tumor progression.