Transcription factor Zfp281 sustains CD4+ T lymphocyte activation by directly repressing Ctla-4 transcription

Expression of co-inhibitory receptors, such as CTLA-4, on effector T cells is a key mechanism for the negative regulation of T cell activation. However, how CTLA-4 is transcriptionally regulated is not well understood. Zfp281, a C2H2 zinc finger protein, is a negative regulator of maintaining pluripotency for embryonic stem cells. Nevertheless, its function in differentiated cells has not been studied. We generated Zfp281 conditional knockout mice in which the function of Zfp281 gene was conditionally disrupted by Cd4Cre transgene to study its impact on T cell function. Zfp281 was dispensable for T cell development, but CD4+ T cell activation and cytokine production were impaired due to diminished T cell receptor signaling. Furthermore, Zfp281 deficiency inhibited in vivo T cell responses to Listeria monocytogenes infection. Using genome-wide expression profiling assays, we determined that Zfp281 repressed Ctla-4 expression by directly binding GC-rich sites of its promoter, which inhibited the negative feedback of T cell activation. In line with this, CTLA-4 blockade and shRNA knock down can partly rescue the reduced cytokine production caused by Zfp281 deficiency. These findings identify that Zfp281 sustains CD4+ T lymphocyte activation by directly repressing Ctla-4 transcription. Overall design: CD4+ T cell RNA-SEQ

效应T细胞上的共抑制受体（co-inhibitory receptors）如细胞毒性T淋巴细胞相关蛋白4（CTLA-4）的表达，是负调控T细胞活化的关键机制。然而，目前对于CTLA-4的转录调控机制仍不甚明晰。Zfp281作为一种C2H2锌指蛋白（C2H2 zinc finger protein），是维持胚胎干细胞（embryonic stem cells）多能性的负调控因子，但其在分化细胞中的功能尚未得到研究。我们构建了Zfp281条件性敲除小鼠，通过Cd4Cre转基因（Cd4Cre transgene）条件性敲除Zfp281基因，以探究其对T细胞功能的影响。Zfp281对T细胞发育并非必需，但CD4+ T细胞的活化与细胞因子产生因T细胞受体信号通路减弱而受损。进一步研究发现，Zfp281缺陷会抑制小鼠体内针对单核细胞增生李斯特菌（Listeria monocytogenes）感染的T细胞应答。通过全基因组表达谱分析（genome-wide expression profiling assays），我们证实Zfp281可直接结合Ctla-4启动子的GC富集位点，从而抑制其表达，进而阻断T细胞活化的负反馈通路。与此相符的是，CTLA-4阻断实验及短发夹RNA（shRNA）敲低实验可部分挽救Zfp281缺陷导致的细胞因子产生减少表型。本研究表明Zfp281通过直接抑制Ctla-4转录，维持CD4+ T淋巴细胞的活化。整体实验设计：CD4+ T细胞RNA测序（RNA-SEQ）