title: A decline in Wnt3a signaling is necessary for mesenchymal stem cells to proceed to replicative senescence.
abstract: Umbilical cord blood-derived mesenchymal stem cells are a promising source of cells for regeneration therapy due to their multipotency, high proliferative capacity, relatively noninvasive collection, and ready availability. However, extended cell culture inevitably triggers cellular senescence-the irreversible arrest of cell division-thereby limiting the proliferative lifespan of adult stem cells. Wnt/β-catenin signaling plays a functional role as a key regulator of self-renewal and differentiation in mesenchymal stem cells (MSCs), and thus Wnt/β-catenin signaling and cellular senescence might be closely connected. Here, we show that the expression levels of canonical Wnt families decrease as MSCs age during subculture. Activation of the Wnt pathway by treatment with Wnt3a-conditioned medium or glycogen synthase kinase 3β inhibitors, such as SB-216763 and 6-bromoindirubin-3'-oxime, delays the progression of cellular senescence as shown by the decrease in the senescence effectors p53 and pRb, lowered senescence-associated β-galactosidase activity, and increased telomerase activity. In contrast, suppression of the Wnt pathway by treatment with dickkopf-1 (an antagonist of the Wnt coreceptor) and β-catenin siRNA transfection promotes senescence in MSCs. Interestingly, the magnitude of the response to enhanced Wnt3a/β-catenin signaling appears to depend on the senescent state during extended culture, particularly after multiple passages. These results suggest that Wnt3a signaling might be a predominant factor that could be used to overcome senescence in long-term cultured MSCs by directly intervening in the proliferative capacity and MSC senescence. The functional role of Wnt3a/β-catenin signaling in hedging cellular senescence may allow the development of new approaches for stem cell-based therapies.
authors.affiliation: 1 Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Ji Yung
authors.initials: JY
authors.lastname: Jeoung
authors.forename: Hae Yun
authors.initials: HY
authors.lastname: Nam
authors.forename: Jihye
authors.initials: J
authors.lastname: Kwak
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Jin
authors.forename: Hyang Ju
authors.initials: HJ
authors.lastname: Lee
authors.forename: Byoung Wook
authors.initials: BW
authors.lastname: Lee
authors.forename: Jong Hyeok
authors.initials: JH
authors.lastname: Baek
authors.forename: Jin Sup
authors.initials: JS
authors.lastname: Eom
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Chang
authors.forename: Dong-Myung
authors.initials: DM
authors.lastname: Shin
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Choi
authors.forename: Seong Who
authors.initials: SW
authors.lastname: Kim
mesh_terms: D002460:Cell Line; D016922:Cellular Senescence; D004261:DNA Replication; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000502:physiology; D060490:Receptors, Wnt / Q000037:antagonists & inhibitors; D019098:Telomerase / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D060490:Receptors, Wnt; D016159:Tumor Suppressor Protein p53; D051176:beta Catenin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D019098:Telomerase