Forrai Ariel, Boyle Kristy, Hart Adam H, Hartley Lynne, Rakar Steven, Willson Tracy A, Simpson Ken M, Roberts Andrew W, Alexander Warren S, Voss Anne K, Robb Lorraine
The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.
Stem Cells. 2006 Mar;24(3):604-14. doi: 10.1634/stemcells.2005-0323. Epub 2005 Aug 25.
Leukemia inhibitory factor (LIF) is required to maintain pluripotency and permit self-renewal of murine embryonic stem (ES) cells. LIF binds to a receptor complex of LIFR-beta and gp130 and signals via the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway, with signalling attenuated by suppressor of cytokine signalling (SOCS) proteins. Recent in vivo studies have highlighted the role of SOCS-3 in the negative regulation of signalling via gp130. To determine the role of SOCS-3 in ES cell biology, SOCS-3-null ES cell lines were generated. When cultured in LIF levels that sustain self-renewal of wild-type cells, SOCS-3-null ES cell lines exhibited less self-renewal and greater differentiation into primitive endoderm. The absence of SOCS-3 enhanced JAK-STAT and extracellular signal-related kinase 1/2 (ERK-1/2)-mitogen-activated protein kinase (MAPK) signal transduction via gp130, with higher levels of phosphorylated STAT-1, STAT-3, SH-2 domain-containing cytoplasmic protein tyrosine phosphatase 2 (SHP-2), and ERK-1/2 in steady state and in response to LIF stimulation. Attenuation of ERK signalling by the addition of MAPK/ERK kinase (MEK) inhibitors to SOCS-3-null ES cell cultures rescued the differentiation phenotype, but did not restore proliferation to wild-type levels. In summary, SOCS-3 plays a crucial role in the regulation of the LIF signalling pathway in murine ES cells. Its absence perturbs the balance between activation of the JAK-STAT and SHP-2-ERK-1/2-MAPK pathways, resulting in less self-renewal and a greater potential for differentiation into the primitive endoderm lineage.
白血病抑制因子（LIF）是维持小鼠胚胎干细胞（ES细胞）多能性并使其自我更新所必需的。LIF与LIFR-β和gp130的受体复合物结合，并通过Janus激酶-信号转导子和转录激活子（JAK-STAT）途径进行信号传导，细胞因子信号抑制蛋白（SOCS）可减弱该信号传导。最近的体内研究突出了SOCS-3在通过gp130进行信号负调控中的作用。为了确定SOCS-3在ES细胞生物学中的作用，构建了SOCS-3基因缺失的ES细胞系。当在维持野生型细胞自我更新的LIF水平下培养时，SOCS-3基因缺失的ES细胞系表现出较少的自我更新能力，并更易分化为原始内胚层。SOCS-3的缺失增强了通过gp130的JAK-STAT和细胞外信号调节激酶1/2（ERK-1/2）-丝裂原活化蛋白激酶（MAPK）信号转导，在稳态以及对LIF刺激的反应中，磷酸化的STAT-1、STAT-3、含SH-2结构域的细胞质蛋白酪氨酸磷酸酶2（SHP-2）和ERK-1/2水平更高。通过向SOCS-3基因缺失的ES细胞培养物中添加MAPK/ERK激酶（MEK）抑制剂来减弱ERK信号传导，挽救了分化表型，但未将增殖恢复到野生型水平。总之，SOCS-3在小鼠ES细胞的LIF信号通路调节中起关键作用。它的缺失扰乱了JAK-STAT和SHP-2-ERK-1/2-MAPK通路激活之间的平衡，导致自我更新减少以及分化为原始内胚层谱系的潜力增加。
