WNT signaling pathway regulates several processes involved in the homeostasis of normal cells. Its dysregulation is associated with pathological outcomes like cancer. We previously demonstrated that downregulation of WNT7A correlates with higher proliferation rates in acute lymphoblastic leukemia. However, the regulation of this gene in pathological and normal conditions remains unexplored. In this work, we aimed to analyze the transcriptional regulation of WNT7A in leukemic cells and in normal T lymphocytes after a proliferative stimulus. WNT7A expression was measured in blood cells and in T lymphocytes after phytohemagglutinin-L (PHA-L) treatment or T-cell receptor (TCR) activation by qPCR and Western blot. Promoter methylation was assessed using methylation-sensitive restriction enzymes, and histone modifications were determined by chromatin immunoprecipitation and qPCR. In T-cell acute lymphoblastic leukemia (T-ALL), WNT7A expression is silenced through DNA methylation of CpG island in the promoter region. In normal peripheral blood cells, WNT7A is mainly expressed by monocytes and T lymphocytes. TCR activation induces the downregulation of WNT7A in normal T lymphocytes by changes in histone methylation marks (H3K4me2/3) and histone deacetylases. A proliferative stimulus mediated by IL-2 keeps WNT7A expression at low levels but in the absence of IL-2, the expression of this gene tends to be restored. Furthermore, after TCR activation and WNT7A downregulation, target genes associated with the WNT canonical pathway were upregulated indicating an independent activity of WNT7A from the WNT canonical pathway. WNT7A expression is silenced by long-term DNA methylation in T-ALL-derived cells and downregulated by histone modifications after TCR activation in normal T lymphocytes.

WNT信号通路调节正常细胞体内稳态涉及的几个过程。其失调与诸如癌症的病理结果有关。我们以前证明WNT7A的下调与急性淋巴细胞白血病中较高的增殖率相关。然而，在病理和正常情况下该基因的调控仍未探索。在这项工作中，我们旨在分析增生性刺激后白血病细胞和正常T淋巴细胞中WNT7A的转录调控。在植物血凝素-L（PHA-L）处理或T细胞受体（TCR）激活后，通过qPCR和Western印迹检测了血细胞和T淋巴细胞中WNT7A的表达。使用对甲基化敏感的限制酶评估启动子甲基化，通过染色质免疫沉淀和qPCR确定组蛋白修饰。在T细胞急性淋巴细胞白血病（T-ALL）中，WNT7A表达通过启动子区域CpG岛的DNA甲基化而沉默。在正常的外周血细胞中，WNT7A主要由单核细胞和T淋巴细胞表达。TCR激活通过组蛋白甲基化标记（H3K4me2 / 3）和组蛋白脱乙酰基酶的变化诱导正常T淋巴细胞WNT7A的下调。由IL-2介导的增殖刺激使WNT7A表达保持较低水平，但在没有IL-2的情况下，该基因的表达趋于恢复。此外，TCR激活和WNT7A下调后，与WNT规范途径相关的靶基因被上调，表明WNT7A与WNT规范途径具有独立的活性。