title: Involvement of the Wnt signaling pathway in feeder‑free culture of human induced pluripotent stem cells.
abstract: Activin A maintains the pluripotency of human induced pluripotent stem (hiPS) cells. A combination of activin A and CHIR99021 (CHIR), a specific inhibitor of glycogen synthase‑3β, is suitable for feeder‑free culture of hiPS cells. In the present study, the specific role of the Wnt signaling pathway in cells cultured under different conditions was investigated. Following transfection with the reporter plasmids, TOPflash and FOPflash, hiPS cells were cultured in medium, containing activin A, CHIR, leukemia inhibitory factor (LIF) or SB431542, a specific inhibitor of activin A. A luciferase reporter assay was performed 48 h later. Western blot analysis was performed to determine the expression levels of β‑catenin and tubulin‑α. The activity of Wnt in hiPS cells was suppressed by culture in the presence of activin A. The activation of the Wnt pathway was most marked when the cells were cultured with a combination of activin A and CHIR. Addition of SB431542 into the culture revealed no significant change in the Wnt pathway. Western blot analysis revealed that β‑catenin accumulated most often in cells cultured with activin A and CHIR. β‑catenin also accumulated in cells cultured with activin A alone. Culture with activin A and CHIR most effectively stimulated the Wnt signaling pathway, as measured by luciferase assays using TOPflash and FOP flash as reporter plasmids. β‑catenin accumulated in the hiPS cells cultured with activin A, via a mechanism, which remains to be elucidated. The Wnt signaling pathway may be important for hiPS cell growth in feeder‑free culture.
authors.affiliation: Department of Gastroenterology, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Tomizawa
authors.affiliation: Department of Radiology, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Fuminobu
authors.initials: F
authors.lastname: Shinozaki
authors.affiliation: Department of Neurology, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Motoyoshi
authors.affiliation: Department of Rheumatology, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Sugiyama
authors.affiliation: Department of Pediatrics, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Department of Neurosurgery, National Hospital Organization, Shimoshizu Hospital, Yotsukaido, Chiba 284‑0003, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishige
mesh_terms: D002478:Cells, Cultured; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D015533:Transcriptional Activation; D014404:Tubulin / Q000235:genetics / Q000378:metabolism; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: C495270:CTNNB1 protein, human; D014404:Tubulin; D051176:beta Catenin; D008156:Luciferases