Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan; National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
Stem Cell Reports. 2018 Jan 9;10(1):272-286. doi: 10.1016/j.stemcr.2017.11.007. Epub 2017 Dec 14.
Mouse embryonic stem cells (ESCs) differentiate into multiple cell types during organismal development. Fibroblast growth factor 4 (FGF4) signaling induces differentiation from ESCs via the phosphorylation of downstream molecules such as mitogen-activated protein kinase/extracellular signal-related kinase (MEK) and extracellular signal-related kinase 1/2 (ERK1/2). The FGF4-MEK-ERK1/2 pathway is inhibited to maintain ESCs in the undifferentiated state. However, the inhibitory mechanism of the FGF4-MEK-ERK1/2 pathway in ESCs is uncharacterized. O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a post-translational modification characterized by the attachment of a single N-acetylglucosamine (GlcNAc) to the serine and threonine residues of nuclear or cytoplasmic proteins. Here, we showed that the O-GlcNAc on the phosphorylation site of PKCζ inhibits PKCζ phosphorylation (activation) and, consequently, the FGF4-PKCζ-MEK-ERK1/2 pathway in ESCs. Our results demonstrate the mechanism for the maintenance of the undifferentiated state of ESCs via the inhibition of the FGF4-PKCζ-MEK-ERK1/2 pathway by O-GlcNAcylation on PKCζ.
鼠胚胎干细胞（ESCs）在个体发育过程中分化为多种细胞类型。成纤维细胞生长因子 4（FGF4）信号通过磷酸化下游分子如丝裂原活化蛋白激酶/细胞外信号调节激酶（MEK）和细胞外信号相关激酶 1/2（ERK1/2）诱导 ESCs 的分化。FGF4-MEK-ERK1/2 途径被抑制以维持 ESCs 处于未分化状态。然而，FGF4-MEK-ERK1/2 途径在 ESCs 中的抑制机制尚未确定。O-连接的β-N-乙酰氨基葡萄糖基化（O-GlcNAcylation）是一种翻译后修饰，其特征在于单个 N-乙酰氨基葡萄糖（GlcNAc）连接到核或细胞质蛋白的丝氨酸和苏氨酸残基上。在这里，我们表明 PKCζ 磷酸化位点上的 O-GlcNAc 抑制了 PKCζ 的磷酸化（激活），从而抑制了 ESCs 中的 FGF4-PKCζ-MEK-ERK1/2 途径。我们的结果表明，通过 O-GlcNAcylation 抑制 PKCζ 来维持 ESCs 未分化状态的机制是通过抑制 FGF4-PKCζ-MEK-ERK1/2 途径实现的。
