Differential expression of miR-17∼92 and its predicted gene targets in MPECs and SLECs correlates with differences in cell proliferation. P14 chimeric mice containing 10⁴ D^bGP33-specific CD8 T cells were infected with LCMV, and memory cells were FACS-purified at day 60 after infection, along with naïve P14 cells from uninfected mice. KLRG-1^lo MPECs and KLRG-1^hi SLECs were also FACS-purified at days 4.5 and 9.0 after infection. Total RNA (including small miRNA species) was isolated and miRNA expression profiling was conducted. (A) Heat map representation with unsupervised hierarchical cluster analysis of differentially expressed miRNAs, P ≤ .05. (B) Venn diagram comparison of predicted target list of miRNAs upregulated in SLECs with genes downregulated in SLECs. Common subset of 283 genes that are downregulated in SLECs and predicted to be targets of miRNAs upregulated in SLECs were then intersected with the predicted target list of miR-17∼92. (C) Heat map and (D) bar graph representations of relative expression of miRs -17, -18a, -19a, -19b, -20a, and -92a belonging to the miR-17∼92 cluster. (E) Functional classification of miR-17∼92–predicted target genes that are downregulated in SLECs into cellular processes and pathways. (F) Heat map representation of how increased expression of miR-17∼92 in SLECs regulates pathways that are predicted to affect cell growth and proliferation. Fifty genes predicted to be regulated by miR-17∼92 were functionally classified into 23 annotated pathways in Ingenuity and the z-score of impact on proliferation, expansion, and colony formation pathways is presented as heat map. A positive z-score correlates positively with the activation of a given pathway and is depicted by the orange color in the heat map. (G) P14 chimeric mice containing 10⁴ D^bGP33-specific CD8 T cells were infected with LCMV, and BrdU was administered intraperitoneally at days 4.75 and 6.75 after infection. Six hours later, proliferation of CD8⁺ Thy1.1⁺ KLRG-1^lo MPECs or KLRG-1^hi SLECs was analyzed by flow cytometry. Representative histogram plots and line graphs of BrdU incorporation are shown. Each line represents % BrdU⁺-proliferating MPECs and SLECs in individual mice. Results are representative of 3 independent experiments with 2 to 5 mice per experiment. Paired Student t test was used for statistical significance of difference of means (*P ≤ .05, **P ≤ .01, ***P ≤ .001).