TY - JOUR
T1 - Defining the role of Wnt/β-catenin signaling in the survival, proliferation, and self-renewal of human embryonic stem cells
AU - Dravid, Gautam
AU - Ye, Zhaohui
AU - Hammond, Holly
AU - Chen, Guibin
AU - Pyle, April
AU - Donovan, Peter
AU - Yu, Xiaobing
AU - Cheng, Linzhao
PY - 2005/11
Y1 - 2005/11
N2 - We used a panel of human and mouse fibroblasts with various abilities for supporting the prolonged growth of human embryonic stem cells (hESCs) to elucidate growth factors required for hESC survival, proliferation, and maintenance of the undifferentiated and pluripotent state (self-renewal). We found that supportive feeder cells secrete growth factors required for both hESC survival/proliferation and blocking hESC spontaneous differentiation to achieve self-renewal. The antidifferentiation soluble factor is neither leukemia inhibitory factor nor Wnt, based on blocking experiments using their antagonists. Because Wnt/β-catenin signaling has been implicated in cell-fate determination and stem cell expansion, we further examined the effects of blocking or adding recombinant Wnt proteins on undifferentiated hESCs. In the absence of feeder cell-derived factors, hESCs cultured under a feeder-free condition survived/proliferated poorly and gradually differentiated. Adding recombinant Wnt3a stimulated hESC proliferation but also differentiation. After 4-5 days of Wnt3a treatment, hESCs that survived maintained the undifferentiated phenotype but few could form undifferentiated hESC colonies subsequently. Using a functional reporter assay, we found that the β-catenin-mediated transcriptional activation in the canonical Wnt pathway was minimal in undifferentiated hESCs, but greatly upregulated during differentiation induced by the Wnt treatment and several other methods. Thus, Wnt/β-catenin activation does not suffice to maintain the undifferentiated and pluripotent state of hESCs. We propose a new model for the role of Wnt/β-catenin signaling in undifferentiated hESCs.
AB - We used a panel of human and mouse fibroblasts with various abilities for supporting the prolonged growth of human embryonic stem cells (hESCs) to elucidate growth factors required for hESC survival, proliferation, and maintenance of the undifferentiated and pluripotent state (self-renewal). We found that supportive feeder cells secrete growth factors required for both hESC survival/proliferation and blocking hESC spontaneous differentiation to achieve self-renewal. The antidifferentiation soluble factor is neither leukemia inhibitory factor nor Wnt, based on blocking experiments using their antagonists. Because Wnt/β-catenin signaling has been implicated in cell-fate determination and stem cell expansion, we further examined the effects of blocking or adding recombinant Wnt proteins on undifferentiated hESCs. In the absence of feeder cell-derived factors, hESCs cultured under a feeder-free condition survived/proliferated poorly and gradually differentiated. Adding recombinant Wnt3a stimulated hESC proliferation but also differentiation. After 4-5 days of Wnt3a treatment, hESCs that survived maintained the undifferentiated phenotype but few could form undifferentiated hESC colonies subsequently. Using a functional reporter assay, we found that the β-catenin-mediated transcriptional activation in the canonical Wnt pathway was minimal in undifferentiated hESCs, but greatly upregulated during differentiation induced by the Wnt treatment and several other methods. Thus, Wnt/β-catenin activation does not suffice to maintain the undifferentiated and pluripotent state of hESCs. We propose a new model for the role of Wnt/β-catenin signaling in undifferentiated hESCs.
KW - Cellular proliferation
KW - Colony formation assays
KW - Embryonic stem cell biology
KW - Human embryonic stem cells
KW - Self-renewal
KW - Stem cell differentiation
KW - Wnt signaling
KW - β-catenin signaling
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UR - http://www.scopus.com/inward/citedby.url?scp=28444438841&partnerID=8YFLogxK
U2 - 10.1634/stemcells.2005-0034
DO - 10.1634/stemcells.2005-0034
M3 - Article
C2 - 16002782
AN - SCOPUS:28444438841
VL - 23
SP - 1489
EP - 1501
JO - Stem Cells
JF - Stem Cells
SN - 1066-5099
IS - 10
ER -