Panoply™ Human MAP3K8 Over-expressing Stable Cell Line

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy (HAM) is a severe neuroinflammatory disease for which there is currently no effective treatment. A hallmark of HAM is the transformation of HTLV-1-infected cells into T helper cell type 1 (Th1)-like cells, characterized by excessive production of interferon (IFN)-γ, leading to chronic inflammation. Here, researchers hypothesized that HAM-specific chromatin remodeling plays a crucial role in the overexpression of key genes driving the pathogenesis of inflammation. Through transcriptomic analysis, chromatin accessibility analysis, and biomarker assessment of HTLV-1-related diseases, researchers identified MAP3K8 as a key gene defining the unique inflammatory signature of HAM. MAP3K8 overexpression promotes Th1-like differentiation and persistently activates the MEK-ERK signaling pathway. Furthermore, the mechanism by which HTLV-1 Tax, Fosl2, and c-Jun synergistically induce HAM-characteristic chromatin remodeling in the enhancer region of the MAP3K8 locus was also explored. Crucially, mitogen-activated protein kinase (MEK) inhibitors effectively inhibit the MAP3K8-MEK signaling cascade and significantly reduce inflammatory responses in in vitro culture experiments.

Studies have shown that MAP3K8 overexpression significantly increases the proportion of cells expressing T-bet (a key transcription factor for Th1 differentiation) (Figure 1A). Given the high levels of MAP3K8 expression observed in HTLV-1 infected cells from HAM patients, researchers constructed three stable MAP3K8-expressing T cell lines (MAP3K8-Jurkat) to assess its functional effects. In MAP3K8-overexpressing cells, the phosphorylation levels of MEK1/2, ERK1/2, and p38 were significantly increased, indicating constitutive activation of the MEK-ERK and p38 signaling pathways (Figure 1B). MAP3K8 activation was accompanied by significant upregulation of IFNG and TBX21, two key genes in inflammatory responses and Th1 cell differentiation (Figure 1C). To further investigate the transcriptomic changes induced by MAP3K8 overexpression, researchers used RNA-Seq technology to compare the gene expression profiles of MAP3K8-overexpressing Jurkat cells and control cells. This analysis identified 906 genes that were upregulated more than 2-fold in MAP3K8-overexpressing Jurkat cells compared to the mock control group. Gene ontology analysis of these upregulated genes revealed that they were significantly enriched in pathways associated with immune responses, inflammatory responses, and mitogen-activated protein kinase pathways (Figures 1D and E).

Figure 1. Functions of overexpressed MAP3K8 on normal CD4+ T cells and Jurkat cells. (Nakashima M, et al., 2025)