title: Identification of positive and negative regulatory elements governing cell-type-specific expression of the neural cell adhesion molecule gene.
abstract: The neural cell adhesion molecule (NCAM) is one of the most prevalent cell adhesion molecules in vertebrates. Its expression is subject to complex cell-type- and developmental-stage-dependent regulation. To study this regulation at the level of transcription, we analyzed the promoter region of the mouse NCAM gene. The NCAM promoter did not contain a typical TATA box. Transcription started at several sites that were used indiscriminately by different cell types, implying that the different NCAM isoforms are expressed from a single promoter. Sequences responsible for both promotion and inhibition of transcription resided within 840 base pairs upstream of the main transcriptional start site. The sequence from positions -645 to -37 relative to the translation initiation site directed high levels of expression in NCAM-expressing N2A cells. The same fragment was six times less active but still significantly active in L cells, but this activity was repressed by inclusion of an additional upstream segment. We mapped eight domains of interactions with nuclear proteins within the 840-base-pair region. The segment with maximum promoter activity contained two adjacent footprints, the occupation of which appeared to be mutually exclusive. One of them corresponded to an Sp1-factor-binding consensus site, the other one bound a factor with nuclear factor I activity. The single protected domain in the fragment harboring a repressor activity consisted of a GGA repeat resembling negative regulatory elements in other promoters. Three adjacent binding sites occupied an A + T-rich segment and contained ATTA motifs also found in the recognition elements of homeodomain proteins. These results show that negative and positive elements interact to regulate the tissue-specific patterns of expression of the NCAM gene and indicate that a factor related to nuclear factor I is involved in its transcriptional control.
authors.affiliation: Centre d'Immunologie Institut National de la Santé, Marseille-Luminy, France.
authors.forename: M R
authors.initials: MR
authors.lastname: Hirsch
authors.forename: L
authors.initials: L
authors.lastname: Gaugler
authors.forename: H
authors.initials: H
authors.lastname: Deagostini-Bazin
authors.forename: L
authors.initials: L
authors.lastname: Bally-Cuif
authors.forename: C
authors.initials: C
authors.lastname: Goridis
mesh_terms: D000818:Animals; D001483:Base Sequence; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D002467:Cell Nucleus / Q000502:physiology; D003001:Cloning, Molecular; D003850:Deoxyribonuclease I / Q000494:pharmacology; D005786:Gene Expression Regulation; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D014158:Transcription, Genetic
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D003850:Deoxyribonuclease I