Pronounced oncogenic function of nuclear TCL1A. (A) Experimental setup of adoptive transfer of hTCL1A transgenic stem cells, HSC/HPC isolated from B6.SJL donor mice, were retrovirally transduced with vectors expressing different variants of hTCL1A (bottom). hTCL1A: unrestricted WT TCL1A; myr-hTCL1A: membrane-targeted TCL1A expression; nls-hTCL1A: nuclear enrichment of TCL1A. After transduction, cells were injected into bone marrow–depleted C57BL/6 mice. (B) Immunofluorescence images of HEK293T cells retrovirally transduced with 3 different TCL1A variants, validating their subcellular localization. Images were captured at original magnification ×60 using an Axio Scope.A1 fluorescent microscope (Zeiss, Germany). For subcellular distribution of TCL1A in the lymphomatous spleens, see supplemental Figure 1B. (C) Kaplan-Meier curves of mice transplanted with HSC/HPC, expressing generic hTCL1A (orange, N = 5), myr-hTCL1A (green, N = 16), and nls-hTCL1A (red, N = 15). Log-rank test showed a significantly shorter survival of nls-hTCL1A than the hTCL1A-recipient mice. For an overview of disease characteristics of transplanted mice, see supplemental Table 1, and for histology of organs, see supplemental Figure 1C. (D) Gene expression of splenocytes from mice with B-cell malignancies (>70% tumor cell content) was analyzed via microarrays. GSEA identified several deregulated pathways between lymphomas of nls-hTCL1A- vs hTCL1A-recipient mice (false discovery rate [FDR] <0.05). Identified nuclear pathways are upregulated in tumor cells from nls-hTCL1A recipients. Deregulated pathways for TCL1A variants vs GFP only and myr-hTCL1a vs nls-TCL1A are displayed in supplemental Figure 2. (E) Enrichment plots of significantly deregulated pathways involved in cell cycle and in DNA repair between nls-hTCL1A- and hTCL1A-expressing cells. IFNγ, interferon γ; IL2, interleukin 2; IRES, internal ribosomal entry site; LTR, long terminal repeat; TNFα, tumor necrosis factor α; wPRE, woodchuck hepatitis virus post-transcriptional regulatory element.