title: CCAAT/enhancer binding protein isoforms expression in the colon of neonatal mice.
abstract: Development of murine proximal colon follows a complex pattern of morphological and functional differentiation. Molecular mechanisms and factors responsible for colon-specific gene expression remain to be established. In an attempt to identify some of these factors, we examined the expression of the alpha, beta, and delta isoforms of the CCAAT/enhancer binding protein (C/EBP) transcription factor gene family during murine colon development. Whereas C/EBP alpha mRNA levels are reduced during the third post-natal week, C/EBP alpha 42 and 30 kD proteins levels decrease between post-natal days 8 and 21. C/EBP beta mRNA levels increase between post-natal days 4 and 8 and remain constant subsequently, in contrast to a decrease in C/EBP beta protein levels between post-natal days 11 and 15. C/EBP delta mRNA levels increase gradually while C/EBP delta protein levels show variations during post-natal development. Changes in C/EBP DNA binding activity coincides with modifications in C/EBP isoforms expression. By indirect immunofluorescence, we show restriction of C/EBP alpha expression to differentiated surface epithelial cells during crypt formation. C/EBP alpha is predominantly nuclear with some cytoplasmic staining at all developmental stages. C/EBP beta and delta are both predominantly nuclear in crypt and differentiated surface epithelial cells, as well as in various cells of the lamina propria and muscular layers. Thus, specific C/EBP isoforms are differentially regulated during murine colon post-natal development. Differential C/EBP isoforms pattern of expression suggests a role for these transcription factors in colon-specific gene expression during development.
authors.affiliation: Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Québec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Blais
authors.forename: F
authors.initials: F
authors.lastname: Boudreau
authors.forename: J F
authors.initials: JF
authors.lastname: Beaulieu
authors.forename: C
authors.initials: C
authors.lastname: Asselin
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D003106:Colon / Q000196:embryology* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology*; D004742:Enhancer Elements, Genetic / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D007150:Immunohistochemistry; D007536:Isomerism; D051379:Mice; D008813:Mice, Inbred ICR / Q000196:embryology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D014157:Transcription Factors / Q000502:physiology
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors