滤泡辅助性T细胞(TFH)是辅助B细胞应答产生抗体的关键辅助T细胞亚群。申请人报道了转录因子TCF-1调控BCL6-Blimp1轴而启动TFH细胞分化的分子机制。申请人还发现，在TFH细胞中TCF-1主要在核内聚集；体外实验表明TCF-1的一个潜在磷酸化位点的突变(S171E)改变了TCF-1的核定位；体内过表达TCF-1和S171A突变促进了TFH细胞的分化，但S171E突变却没有明显变化；体内过表达已报道的TCF-1的激酶TAK/NLK，发现TFH细胞的分化反而增加了。因此申请人拟用CRISPR-Seq、bPPI-Seq和免疫沉淀质谱联用技术筛选在TFH细胞分化中与TCF-1相互作用而致其磷酸化出核的蛋白激酶，并在该激酶的条件敲除小鼠及TFH细胞失调的相关疾病模型中验证该激酶的作用及其分子机制。本项目的研究成果将为疫苗和佐剂的设计及治疗TFH细胞失调引起的各种疾病提供更好的思路和靶点。

Follicular helper T cells (TFH cells), a unique subset of CD4 helper T cells, are specialized to facilitate the establishment of a GC reaction and the selection of GC B cells bearing high-affinity antigen receptors for final differentiation into long-lived plasma cells and memory B cells. Applicant previous work demonstrated TCF-1, a downstream transcription factor of canonical Wnt pathway, functions as an important hub upstream of the BCL6–Blimp1 axis to initiate and secure the differentiation of TFH cells during acute viral infection. Further, applicant noticed that TCF-1 exhibited nuclear aggregation in TFH cells; the localization of TCF-1 was altered by S171E mutant in vitro; overexpression of TCF-1 S171E mutant showed normal differentiation of TFH cells in vivo, although wild-type TCF-1 and its S171A mutant promoted the differentiation; overexpression of TAK or NLK, reported kinase of TCF-1 in colon cancer cells, enhanced the differentiation of TFH cells by contraries. Thus, using CRISPR-Seq, bPPI-Seq and immunoprecipitation-Mass Spectrum, applicant will screen and validate the protein kinase which can phosphorylate TCF-1 and regulate the nuclear export of phosphorylation TCF-1 in the differentiation of TFH cells. This research will shed new light on providing novel strategies and targets against the design of vaccine and adjuvant and the diseases caused by dysregulation of TFH cells.