title: beta-Catenin regulation during matrigel-induced rat hepatocyte differentiation.
abstract: Hepatocytes in primary cultures de-differentiate and re-differentiate following addition of Engelbreth-Holm-Swarm mouse sarcoma (matrigel) to the cultures. The Wnt/beta-catenin pathway has been shown to be important in liver growth and development. Here, we investigate changes in beta-catenin and its mechanism, during matrigel-induced hepatocyte differentiation. Primary rat hepatocytes were cultured for 8 days, and matrigel was added to half of the cultures. Total and nuclear protein and total RNA were extracted at different days of culture and examined for beta-catenin and other Wnt pathway components. A significant increase in total beta-catenin protein was observed upon matrigel addition, during hepatocyte differentiation, despite a decrease in beta-catenin and frizzled-1 (Wnt receptor) expression. A concurrent decrease in the glycogen synthase kinase-3beta (GSK3beta), axin, and ser45/thr41-phosphorylated beta-catenin proteins was observed in matrigel-treated cultures, implying decreased degradation of beta-catenin. Interestingly, a decrease in nuclear beta-catenin and total active beta-catenin was observed in the presence of matrigel. Matrigel also induced an increased association of beta-catenin with Met (hepatocyte growth factor receptor), whereas association with E-cadherin remained unchanged. This coexisted with decreased beta-catenin tyrosine phosphorylation. Thus, beta-catenin undergoes multifactorial regulation during matrigel-induced hepatocyte differentiation and maturation; this induces its stabilization and membrane translocation, possibly contributing to hepatocyte differentiation.
authors.affiliation: Department of Pathology, School of Medicine, University of Pittsburgh, PA, 15261, USA. smonga@pitt.edu
authors.forename: Satdarshan P S
authors.initials: SP
authors.lastname: Monga
authors.forename: Amanda
authors.initials: A
authors.lastname: Micsenyi
authors.forename: Matt
authors.initials: M
authors.lastname: Germinaro
authors.forename: Udayan
authors.initials: U
authors.lastname: Apte
authors.forename: Aaron
authors.initials: A
authors.lastname: Bell
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology*; D003593:Cytoplasm / Q000378:metabolism; D004338:Drug Combinations; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000502:physiology*; D007797:Laminin / Q000494:pharmacology*; D051379:Mice; D008954:Models, Biological; D011509:Proteoglycans / Q000494:pharmacology*; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D051176:beta Catenin; C059485:matrigel; D003094:Collagen