title: Transcription factor NF-kappaB participates in regulation of epithelial cell turnover in the colon.
abstract: The transcription factor nuclear factor (NF)-kappaB regulates the expression of genes that can influence cell proliferation and death. Here we analyze the contribution of NF-kappaB to the regulation of epithelial cell turnover in the colon. Immunohistochemical, immunoblot, and DNA binding analyses indicate that NF-kappaB complexes change as colonocytes mature: p65-p50 complexes predominate in proliferating epithelial cells of the colon, whereas the p50-p50 dimer is prevalent in mature epithelial cells. NF-kappaB1 (p50) knockout mice were used to study the role of NF-kappaB in regulating epithelial cell turnover. Knockout animals lacked detectable NF-kappaB DNA binding activity in isolated epithelial cells and had significantly longer crypts with a more extensive proliferative zone than their wild-type counterparts (as determined by proliferating cell nuclear antigen staining and in vivo bromodeoxyuridine labeling). Gene expression profiling reveals that the NF-kappaB1 knockout mice express the potentially growth-enhancing tumor necrosis factor (TNF)-alpha and nerve growth factor-alpha genes at elevated levels, with in situ hybridization localizing some of the TNF-alpha expression to epithelial cells. TNF-alpha is NF-kappaB regulated, and its upregulation in NF-kappaB1 knockouts may result from an alleviation of p50-p50 repression. NF-kappaB complexes may therefore influence cell proliferation in the colon through their ability to selectively activate and/or repress gene expression.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Inan
authors.forename: V
authors.initials: V
authors.lastname: Tolmacheva
authors.forename: Q S
authors.initials: QS
authors.lastname: Wang
authors.forename: D W
authors.initials: DW
authors.lastname: Rosenberg
authors.forename: C
authors.initials: C
authors.lastname: Giardina
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D003106:Colon / Q000033:anatomy & histology*; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000502:physiology*; D015870:Gene Expression; D020287:In Situ Nick-End Labeling; D007413:Intestinal Mucosa / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
chemical_list: D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000469:Alkaline Phosphatase