Figure 2. The regulation of CCR7 expression in T cells. The distinguishing features of naïve, TE, and TM cells reflect different programs of gene expression regulated by various factors. First, the gene encoding CCR7 protein is modulated by epigenetic mechanisms, such as methylation. The CCR7 chromatin can silenced by methylation of the promoter regions, in which transcription factor binding sites such as Sp1 and Ets-1 in effector and TEM cells are located. In contrast, this locus is demethylated, allowing the gene to be expressed in naïve and TCM cells. Additional inhibitory mechanisms of CCR7 gene expression include miRNA-dependent regulation. The indicated miRNAs such as let-7α and miR-21 bind to the 3′ UTR of CCR7 mRNA and decay the mRNA, thereby inhibiting translation efficiency. Following the translation, CCR7 protein can be post-translationally modified to modulate their affinity with their ligands, CCL19 and CCL21. The glycosylation of N-terminus of CCR7 protein suppresses CCR7 activity, while sulfation increases its affinity for the ligands.
