Hills Leonard Benjamin, Abdullah Leena, Lust Hannah E, Degefu Hanna, Huang Yina H
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756; and.
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756; and
J Immunol. 2021 Jan 1;206(1):89-100. doi: 10.4049/jimmunol.2000216. Epub 2020 Nov 23.
Foxo1 is an essential transcription factor required for the survival and differentiation of memory CD8 T cells, yet it is unclear whether these Foxo1-dependent functions are inherently coupled. To address this question, we examined the effects of different Foxo1 posttranslational modifications. Phosphorylation of Foxo1 by Akt kinases at three distinct residues is well characterized to inhibit Foxo1 transcriptional activity. However, the effect of Foxo1 phosphorylation within its DNA-binding domain at serine 209 by Mst1 kinase is not fully understood. In this study, we show that an S209A phospho-null Foxo1 exhibited Akt-dependent nuclear trafficking in mouse CD8 T cells and augmented the expression of canonical Foxo1 target genes such as and In contrast, an S209D phosphomimetic Foxo1 (SD-Foxo1) was largely excluded from the nucleus of CD8 T cells and failed to transactivate these genes. RNA sequencing analysis revealed that SD-Foxo1 was associated with a distinct Foxo1-dependent transcriptional profile, including genes mediating CD8 effector function and cell survival. Despite defective transactivation of canonical target genes, SD-Foxo1 promoted IL-15-mediated CD8 T cell survival in vitro and survival of short-lived effector cells in vivo in response to infection. However, SD-Foxo1 actively repressed CD127 expression and failed to generate memory precursors and long-lived memory T cells. Together, these data indicate that S209 is a critical residue for the regulation of Foxo1 subcellular localization and for balancing CD8 T cell differentiation and survival.
Foxo1是记忆性CD8 T细胞存活和分化所必需的一种关键转录因子，但目前尚不清楚这些依赖Foxo1的功能是否内在相关。为了解决这个问题，我们研究了不同的Foxo1翻译后修饰的影响。Akt激酶在三个不同位点对Foxo1的磷酸化已被充分表征为可抑制Foxo1的转录活性。然而，Mst1激酶在丝氨酸209位点对其DNA结合域内的Foxo1磷酸化的影响尚未完全明确。在本研究中，我们发现S209A磷酸化缺失的Foxo1在小鼠CD8 T细胞中表现出Akt依赖性的核转运，并增强了典型的Foxo1靶基因如 和 的表达。相比之下，S209D磷酸模拟型Foxo1（SD-Foxo1）在很大程度上被排除在CD8 T细胞的细胞核之外，并且无法激活这些基因。RNA测序分析表明，SD-Foxo1与一种独特的依赖Foxo1的转录谱相关，包括介导CD8效应功能和细胞存活的基因。尽管对典型靶基因的转录激活存在缺陷，但SD-Foxo1在体外促进了IL-15介导的CD8 T细胞存活，并在体内促进了短期效应细胞在应对 感染时的存活。然而，SD-Foxo1积极抑制CD127的表达，并且无法产生记忆前体细胞和长寿记忆T细胞。总之，这些数据表明S209是调节Foxo1亚细胞定位以及平衡CD8 T细胞分化和存活的关键残基。
