title: Cloning of the human activated leukocyte cell adhesion molecule promoter and identification of its tissue-independent transcriptional activation by Sp1.
abstract: Activated leukocyte cell adhesion molecule (ALCAM) belongs to the immunoglobulin cell adhesion molecule super family. ALCAM is implicated in tumor progression, inflammation, and the differentiation of hematopoietic stem cells. Hitherto, the identity of regulatory DNA elements and cognate transcription factors responsible for ALCAM gene expression remained unknown. In this report, the human ALCAM promoter was cloned and its transcriptional mechanisms elucidated. The promoter is TATA-less and contains multiple GC-boxes. A proximal 650-bp promoter fragment conferred tissue-independent activation, whereas two contiguous regions upstream of this region negatively influenced promoter activity in a tissue-specific manner. The positive regulatory promoter region was mapped to a core 50 base pair sequence containing a conical Sp1 element. Mutation analysis revealed that this element alone or in tandem with elements immediately upstream was required for maximal promoter activity. Chromatin analysis revealed that Sp1 binds exclusively to the canonical binding sequence in vivo, but not to DNA sequence immediately upstream. Finally, we showed that over-expression of Sp1 significantly increased the basal promoter activity. Thus, Sp1 activated the ALCAM promoter in most cells. These findings have important ramifications for unraveling the roles of ALCAM in inflammation and tumorigenesis.
authors.affiliation: Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Tan
authors.forename: Flaubert
authors.initials: F
authors.lastname: Mbunkui
authors.forename: Solomon F
authors.initials: SF
authors.lastname: Ofori-Acquah
mesh_terms: D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D042783:Endothelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016329:Sp1 Transcription Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D020410:Activated-Leukocyte Cell Adhesion Molecule; D002843:Chromatin; D016329:Sp1 Transcription Factor