title: beta-Catenin stabilization imparts crypt progenitor phenotype to hyperproliferating colonic epithelia.
abstract: Utilizing the Citrobacter rodentium (CR)-induced transmissible murine colonic hyperplasia (TMCH) model, we provide mechanistic basis of changes in beta-catenin/APC/CKIepsilon leading to progression and/or regression of hyperplasia in vivo. In response to CR-induced TMCH, crypt lengths increased significantly between days 6-27 post-infection, followed by a steep decline by day 34. beta-Cat(45)/total beta-catenin were elevated on day 1 post-infection, preceding changes in crypt length, and persisted for 27 days before declining by day 34. Importantly, cellular CKIepsilon and beta-catenin co-immunoprecipitated and exhibited remarkable parallel changes in kinetics during hyperplasia/regression phases. beta-catenin, phosphorylated at Ser33,37 and Thr41 (beta-cat(33,37/41)), was low till day 12, followed by gradual increase until day 27 before declining by day 34. GSK-3beta exhibited significant Ser(9)-phosphorylation/inactivation at days 6-12 with partial recovery at days 27-34. Wild type (wt) APC (p312) levels increased at day 6 with transient proteolysis/truncation to p130 form between days 12 and 15; p312 reappeared by day 19 and returned to baseline by day 34. The kinetics of beta-Cat(45)/beta-catenin nuclear accumulation and acetylation (Ac-beta-Cat(Lys49)) from days 6 to 27, followed by loss of phosphorylation/acetylation by day 34 was almost identical; Tcf-4 co-immunoprecipitated with beta-Cat(45)/beta-catenin and localized immunohistochemically to beta-Cat(41/45)-positive regions leading to elevated cyclin D1 expression, during the hyperproliferative, but not regression phases of TMCH. CKIepsilon mediated phosphorylation of beta-Cat(45), resulting in stabilization/nuclear translocation of beta-Cat(45) may be critical for maintaining proliferation at days 6-27. Reversal of GSK-3beta phosphorylation and APC changes may be equally critical during the regression phase from days 27 to 34.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston TX, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Sellin
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Pomila
authors.initials: P
authors.lastname: Singh
authors.forename: Shahid
authors.initials: S
authors.lastname: Umar
mesh_terms: D000107:Acetylation; D025601:Adenomatous Polyposis Coli Protein / Q000378:metabolism; D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D003106:Colon / Q000201:enzymology / Q000473:pathology*; D019938:Cyclin D1 / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology*; D005629:Frozen Sections; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006965:Hyperplasia; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D051379:Mice; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D055550:Protein Stability; D021381:Protein Transport; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D051820:TCF Transcription Factors / Q000378:metabolism; D000073940:Transcription Factor 4; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D009419:Nerve Tissue Proteins; D018809:Proliferating Cell Nuclear Antigen; D051820:TCF Transcription Factors; C090743:Tcf4 protein, mouse; D000073940:Transcription Factor 4; D051176:beta Catenin; D019938:Cyclin D1; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3