Nuclear factors TOX and TOX2 upregulate TIM3 expression and lead to T-cell exhaustion in malignancies. Here, we demonstrate two distinct TIM3 expression patterns (high & low) with high TOX and TOX2 levels in T-cell acute lymphoblastic leukemia (T-ALL) specimens and cell lines. However, the mechanisms regulated by TOX and TIM3 signaling in leukemogenesis are unclear. We found that TOX and TOX2 proteins each directly upregulated HAVCR2 transcription, while the cellular localization of TOX2 was different in Jurkat and MOLT3 cells (nucleus) and lymphoblastic cell T2 and normal T cells (cytoplasm). Nuclear TOX and TOX2 formed a protein complex and repressed HAVCR2 promoter activity by recruiting transcriptional corepressor LCOR and deacetylase HDAC3. The nuclear-cytosol translocation of TOX2 was deacetylation-dependent and cooperatively mediated by deacetylase Sirt1 and kinase TBK1. Radiation damage induced TOX2 nuclear translocation and decreased Sirt1, TIM3, and caspase 1 expression in normal T cells. Accordingly, knockdown of TOX, TOX2 or LCOR; HDAC3 inhibition; or TIM3 overexpression induced Jurkat cell apoptosis in vitro and slow growth in vivo. Thus, our findings demonstrate a novel regulatory mechanism involving TOX-TOX2 and the TIM3 pathway in the leukemogenesis of T-ALL.

核因子 TOX 和 TOX2 上调 TIM3 表达并导致恶性肿瘤中的 T 细胞耗竭。在这里，我们在T细胞急性淋巴细胞白血病（T-ALL）标本和细胞系中展示了两种不同的TIM3表达模式（高和低），具有高TOX和TOX2水平。然而，TOX 和 TIM3 信号转导在白血病发生中调节的机制尚不清楚。我们发现 TOX 和 TOX2 蛋白分别直接上调 HAVCR2 转录，而 TOX2 的细胞定位在 Jurkat 和 MOLT3 细胞 （细胞核） 以及淋巴细胞 T2 和正常 T 细胞 （细胞质） 中不同。核 TOX 和 TOX2 形成蛋白质复合物，并通过募集转录辅阻遏物 LCOR 和脱乙酰酶 HDAC3 抑制 HAVCR2 启动子活性。TOX2 的核胞质溶胶易位是脱乙酰依赖性的，由脱乙酰酶 Sirt1 和激酶 TBK1 协同介导。辐射损伤诱导正常 T 细胞中 TOX2 核转位并降低 Sirt1 、 TIM3 和 caspase 1 的表达。因此，敲低 TOX、TOX2 或 LCOR;HDAC3 抑制;或 TIM3 过表达在体外诱导 Jurkat 细胞凋亡，在体内缓慢生长。因此，我们的研究结果证明了一种涉及 TOX-TOX2 和 TIM3 通路在 T-ALL 白血病发生中的新调节机制。