Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, UK.
Protein Phosphorylation and Ubiquitylation Unit, James Black Centre, School of Life Sciences, Dundee, UK.
FEBS Lett. 2021 Jan;595(1):14-25. doi: 10.1002/1873-3468.13969. Epub 2020 Nov 18.
The self-renewal efficiency of mouse embryonic stem cells (ESCs) is determined by the concentration of the transcription factor NANOG. While NANOG binds thousands of sites in chromatin, the regulatory systems that control DNA binding are poorly characterised. Here, we show that NANOG is phosphorylated by casein kinase I, and identify target residues. Phosphomimetic substitutions at phosphorylation sites within the homeodomain (S130 and S131) have site-specific functional effects. Phosphomimetic substitution of S130 abolishes DNA binding by NANOG and eliminates LIF-independent self-renewal. In contrast, phosphomimetic substitution of S131 enhances LIF-independent self-renewal, without influencing DNA binding. Modelling the DNA-homeodomain complex explains the disparate effects of these phosphomimetic substitutions. These results indicate how phosphorylation may influence NANOG homeodomain interactions that underpin ESC self-renewal.
小鼠胚胎干细胞 (ESC) 的自我更新效率由转录因子 NANOG 的浓度决定。虽然 NANOG 结合染色质中的数千个位点,但控制 DNA 结合的调节系统的特征描述很差。在这里,我们表明 NANOG 被酪蛋白激酶 I 磷酸化,并确定了靶位残基。同源域内磷酸化位点的磷酸模拟取代具有特定的功能效应。同源域内 S130 和 S131 位磷酸模拟取代会破坏 NANOG 的 DNA 结合并消除 LIF 非依赖性自我更新。相比之下,S131 位磷酸模拟取代增强了 LIF 非依赖性自我更新,而不影响 DNA 结合。对 DNA-同源域复合物的建模解释了这些磷酸模拟取代的不同作用。这些结果表明磷酸化如何影响 NANOG 同源域相互作用,从而支持 ESC 的自我更新。