Immunological memory is a critical characteristic of a successful long-term adaptive immune response. During the initial phases of antigen:B lymphocyte interactions, B cells participate in the germinal center reaction, in which T-B cell interactions take place. CD154 on T cells acts as a ligand that binds to the CD40 receptor on B cells and facilitates the differentiation of B cells to memory B cells. However, cell fate determinants controlled by CD40 signal for cellular differentiation are unclear. In this study, we explored miRNA and miRNA-targets as cell fate determinants in CD40 signaled B cells. We selected candidate miRNAs based on their involvement in the regulation of B cell development, activation, and differentiation. We found that CD40 signal reduced transcript levels of miR150-5p, 17-5p, 146a-5p, 26a-5p and increased levels of miR292a-5p. Gene set enrichment analyses of previously submitted microarray data revealed accordant changes in levels of gene targets of these miRNA. Gene ontology analysis of miRNA-targets showed enrichment of genes participating in pathways such as DNA damage response, RNA/protein metabolism, and cell cycle regulation. Subsequently, studies on candidate miRNA-targets showed a CD40 signal driven differential regulation of Ccnd2, Pten, Traf6, c-Myb, and Btla. Further, 'gain of function' studies using mimics of the downregulated miRNAs, confirmed a predicted reduction in miRNA responsive targets; such as reduction of Ccnd2 levels in mimic treated groups of miR146a-5p, 26a-5p, and 17-5p. In conclusion, our study reveals that CD40 signal modulates levels of selected miRNAs as well as their cognate targets, whose enriched participation in diverse processes may help delineate downstream cell fate decisions.

免疫记忆是成功的长期适应性免疫反应的关键特征。在抗原：B淋巴细胞相互作用的初始阶段，B细胞参与生发中心反应，其中发生TB细胞相互作用。T细胞上的CD154充当与B细胞上的CD40受体结合的配体，并促进B细胞分化为记忆B细胞。然而，尚不清楚由CD40信号控制的细胞命运决定因素。在这项研究中，我们探索了miRNA和miRNA靶标作为CD40信号B细胞中细胞命运的决定因素。我们基于候选miRNA参与B细胞发育，激活和分化的调控来选择候选miRNA。我们发现CD40信号降低了miR150-5p，17-5p，146a-5p，26a-5p和增加的miR292a-5p水平。对先前提交的微阵列数据的基因集富集分析显示，这些miRNA的基因靶标水平发生了相应的变化。miRNA靶标的基因本体分析显示，参与诸如DNA损伤反应，RNA /蛋白质代谢和细胞周期调控等途径的基因富集。随后，对候选miRNA靶标的研究显示了CD40信号驱动的Ccnd2，Pten，Traf6，c-Myb和Btla的差异调节。此外，使用下调的miRNA的模拟物进行的“功能获得”研究证实了miRNA响应靶标的预期减少。例如在miR146a-5p，26a-5p和17-5p的模拟治疗组中降低Ccnd2水平。总而言之，我们的研究表明CD40信号可调节选定的miRNA及其相关靶标的水平，