title: APC mutant zebrafish uncover a changing temporal requirement for wnt signaling in liver development.
abstract: Developmental signaling pathways hold the keys to unlocking the promise of adult tissue regeneration, and to inhibiting carcinogenesis. Patients with mutations in the Adenomatous Polyposis Coli (APC) gene are at increased risk of developing hepatoblastoma, an embryonal form of liver cancer, suggesting that Wnt affects hepatic progenitor cells. To elucidate the role of APC loss and enhanced Wnt activity in liver development, we examined APC mutant and wnt inducible transgenic zebrafish. APC(+/-) embryos developed enlarged livers through biased induction of hepatic gene programs and increased proliferation. Conversely, APC(-/-) embryos formed no livers. Blastula transplantations determined that the effects of APC loss were cell autonomous. Induction of wnt modulators confirmed biphasic consequences of wnt activation: endodermal pattern formation and gene expression required suppression of wnt signaling in early somitogenesis; later, increased wnt activity altered endodermal fate by enhancing liver growth at the expense of pancreas formation; these effects persisted into the larval stage. In adult APC(+/-) zebrafish, increased wnt activity significantly accelerated liver regeneration after partial hepatectomy. Similarly, liver regeneration was significantly enhanced in APC(Min/+) mice, indicating the conserved effect of Wnt pathway activation in liver regeneration across vertebrate species. These studies reveal an important and time-dependent role for wnt signaling during liver development and regeneration.
authors.affiliation: Stem Cell Program and Hematology/Oncology, Children's Hospital and Dana-Farber Cancer Institute, HHMI, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Goessling
authors.forename: Trista E
authors.initials: TE
authors.lastname: North
authors.forename: Allegra M
authors.initials: AM
authors.lastname: Lord
authors.forename: Craig
authors.initials: C
authors.lastname: Ceol
authors.forename: Sang
authors.initials: S
authors.lastname: Lee
authors.forename: Gilbert
authors.initials: G
authors.lastname: Weidinger
authors.forename: Caitlin
authors.initials: C
authors.lastname: Bourque
authors.forename: Robbert
authors.initials: R
authors.lastname: Strijbosch
authors.forename: Anna-Pavlina
authors.initials: AP
authors.lastname: Haramis
authors.forename: Mark
authors.initials: M
authors.lastname: Puder
authors.forename: Hans
authors.initials: H
authors.lastname: Clevers
authors.forename: Randall T
authors.initials: RT
authors.lastname: Moon
authors.forename: Leonard I
authors.initials: LI
authors.lastname: Zon
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D019521:Body Patterning; D019070:Cell Lineage; D049109:Cell Proliferation; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D004707:Endoderm / Q000166:cytology / Q000196:embryology; D006498:Hepatectomy; D022781:Hepatocytes / Q000166:cytology; D008099:Liver / Q000166:cytology / Q000196:embryology*; D008115:Liver Regeneration; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology; D013997:Time Factors; D051153:Wnt Proteins / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology*; D051176:beta Catenin / Q000378:metabolism
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D051153:Wnt Proteins; D051176:beta Catenin