Niwa H, Burdon T, Chambers I, Smith A
Centre for Genome Research, University of Edinburgh, Edinburgh EH9 3JQ, UK.
Genes Dev. 1998 Jul 1;12(13):2048-60. doi: 10.1101/gad.12.13.2048.
The propagation of embryonic stem (ES) cells in an undifferentiated pluripotent state is dependent on leukemia inhibitory factor (LIF) or related cytokines. These factors act through receptor complexes containing the signal transducer gp130. The downstream mechanisms that lead to ES cell self-renewal have not been delineated, however. In this study, chimeric receptors were introduced into ES cells. Biochemical and functional studies of transfected cells demonstrated a requirement for engagement and activation of the latent trancription factor STAT3. Detailed mutational analyses unexpectedly revealed that the four STAT3 docking sites in gp130 are not functionally equivalent. The role of STAT3 was then investigated using the dominant interfering mutant, STAT3F. ES cells that expressed this molecule constitutively could not be isolated. An episomal supertransfection strategy was therefore used to enable the consequences of STAT3F expression to be examined. In addition, an inducible STAT3F transgene was generated. In both cases, expression of STAT3F in ES cells growing in the presence of LIF specifically abrogated self-renewal and promoted differentiation. These complementary approaches establish that STAT3 plays a central role in the maintenance of the pluripotential stem cell phenotype. This contrasts with the involvement of STAT3 in the induction of differentiation in somatic cell types. Cell type-specific interpretation of STAT3 activation thus appears to be pivotal to the diverse developmental effects of the LIF family of cytokines. Identification of STAT3 as a key transcriptional determinant of ES cell self-renewal represents a first step in the molecular characterization of pluripotency.
胚胎干细胞（ES细胞）在未分化的多能状态下的增殖依赖于白血病抑制因子（LIF）或相关细胞因子。这些因子通过含有信号转导子gp130的受体复合物发挥作用。然而，导致ES细胞自我更新的下游机制尚未明确。在本研究中，将嵌合受体导入ES细胞。对转染细胞的生化和功能研究表明，需要激活潜在的转录因子STAT3。详细的突变分析意外地发现，gp130中的四个STAT3对接位点在功能上并不等同。然后使用显性干扰突变体STAT3F研究STAT3的作用。持续表达该分子的ES细胞无法分离。因此，采用附加型超转染策略来研究STAT3F表达的后果。此外，构建了一个可诱导的STAT3F转基因。在这两种情况下，在LIF存在下生长的ES细胞中STAT3F的表达特异性地消除了自我更新并促进了分化。这些互补的方法证实，STAT3在维持多能干细胞表型中起核心作用。这与STAT3参与体细胞类型的分化诱导形成对比。因此，STAT3激活的细胞类型特异性解读似乎是LIF细胞因子家族不同发育效应的关键。将STAT3鉴定为ES细胞自我更新的关键转录决定因素是多能性分子特征研究的第一步。
