A Panel of Eight miRNAs Is Deregulated in HTLV-2 Infected PBMCs and BJABGu Cell Line

Abstract

Despite human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 being retroviruses closely related at a genomic level, HTLV-2 differs from HTLV-1 in terms of pathogenicity in both single infection and coinfection contexts. Moreover, the HTLV-2 association with clinical outcomes is still debated and several mechanisms underlying HTLV-2 infection remain unexplored as well. Cellular miRNAs are key factors in the post-transcriptional regulation of gene expression and they are known to be potential targets for several pathogens to control the host microenvironment and, in particular, escape immune responses. Here, we identified a HTLV-2-related signature of eight miRNAs (miR-125a-3p, miR-381-3p, miR-502-5p, miR-708-5p, miR-548d-5p, miR-548c-5p, miR-1-3p, and miR-511-5p) in both HTLV-2 infected PBMC and BJABGu cell lines. Altered miRNA expression patterns were correlated with the impairment of Th cell differentiation and signaling pathways driven by cytokines and transcriptional factors such as the Runt-related transcription factor (RUNX) family members. Specifically, we demonstrated that the RUNX2 protein was significantly more expressed in the presence of Tax-2 compared with Tax-1 in an in vitro cell model. To the best of our knowledge, these data represent the first contribution to elucidating the HTLV-2 mediated alteration of host cell miRNA profiles that may impact on HTLV-2 replication and persistent infection.

Keywords: HTLV-2; RUNX; Tax; cell signaling pathways; host-virus interactions; miRNA.

Figure 1

Dendrogram and heat maps of the differentially expressed miRNAs. (a) The hierarchical clustering dendrogram shows the similarities between the expression profiles of the 226 dysregulated miRNAs. (b) The heat map of miRNAs whose expression levels varied by at least 1 log10 (fold change (FC)) in HTLV-2-infected PBMCs (first column) and profile of corresponding miRNAs altered in BJABGu (second column). (c) The heat map of miRNAs with [log10 (FC) > |1|] in BJABGu (first column) and the profile with miRNAs modulated in the HTLV-2-infected PBMCs (second column). Each colored block represents the expression of 1 miRNA (labeled on the right) in the indicated sample. PCR expression signals are converted into color (green, high signal; red, low signal). Color intensities are proportional to the variation of expression, as indicated in the scale bar: values ranged from −2 to + 2 (z score).

Figure 2

Target genes of deregulated miRNAs. The Venn diagram indicates the target genes of differentially expressed (down or upregulated) in HTLV-2-infected PBMCs (a) and BJABGu (b). The target genes that are common between the two groups are listed in the boxes.

Figure 3

Bubble plot of the KEGG pathway enrichment of the target genes. The strength of the enriched signaling pathways associated with the target genes of the downregulated (DW) miRNAs (left panel) and upregulated (UP) miRNAs (right panel) in HTLV-2 infected PBMCs (upper panel) and BJABGu cells (bottom panel). The size and color of each bubble represent the number of target genes in each pathway and its corresponding p-value, respectively.

Figure 4

On the left (a), representative Western blot analysis of the HEK293T control cells and cells transfected with Tax-1 pJFE or Tax-2 pJFE showing an increase in RUNX2 protein expression in cells transfected with the HTLV-2 Tax protein. On the right (b), histogram bars represent the densitometric analysis of the Western blot bands corresponding to RUNX2 normalized to tubulin. ** = p value < 0.01 using one-way ANOVA; c = control non-transfected cells; Tax-1 = cells transfected with Tax-1 pJFE; Tax-2 = cells transfected with Tax-2 pJFE.

Figure 5

Analysis of PPIs of the target genes of miRNAs down regulated and upregulated in infected PBMCs ((a,b) respectively) and BJABGu cells ((c,d) respectively) related to HIV-1 and HTLV-1 annotations. Red nodes are associated with HTLV-1 infection, while blue nodes are associated with HIV-1 infection. Double coloured nodes share both annotations (genes name are listed in Supplementary S2).