Functional Expression Cloning of Nanog, a Pluripotency Sustaining Factor in Embryonic Stem Cells.
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Date
2003Author
Chambers, Ian
Colby, Douglas
Robertson, Morag
Nichols, Jennifer
Lee, Sonia
Tweedie, Susan
Smith, Austin G
Metadata
Abstract
Embryonic stem (ES) cells undergo extended proliferation while remaining poised for
multilineage differentiation. A unique network of transcription factors may
characterize self-renewal and simultaneously suppress differentiation. We applied
expression cloning in mouse ES cells to isolate a self-renewal determinant. Nanog is a
divergent homeodomain protein that directs propagation of undifferentiated ES cells.
Nanog mRNA is present in pluripotent mouse and human cell lines, and absent from
differentiated cells. In preimplantation embryos, Nanog is restricted to founder cells
from which ES cells can be derived. Endogenous Nanog acts in parallel with cytokine
stimulation of Stat3 to drive ES cell self-renewal. Elevated Nanog expression from
transgene constructs is sufficient for clonal expansion of ES cells, bypassing Stat3 and
maintaining Oct4 levels. Cytokine dependence, multilineage differentiation, and
embryo colonization capacity are fully restored upon transgene excision. These
findings establish a central role for Nanog in the transcription factor hierarchy that
defines ES cell identity.