Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt-Ingram Cancer Center, Nashville, TN 37232, USA.
Cell Genom. 2024 Apr 10;4(4):100537. doi: 10.1016/j.xgen.2024.100537.
Transcriptional dysregulation is a hallmark of diffuse large B cell lymphoma (DLBCL), as transcriptional regulators are frequently mutated. However, our mechanistic understanding of how normal transcriptional programs are co-opted in DLBCL has been hindered by a lack of methodologies that provide the temporal resolution required to separate direct and indirect effects on transcriptional control. We applied a chemical-genetic approach to engineer the inducible degradation of the transcription factor FOXO1, which is recurrently mutated (mFOXO1) in DLBCL. The combination of rapid degradation of mFOXO1, nascent transcript detection, and assessment of chromatin accessibility allowed us to identify the direct targets of mFOXO1. mFOXO1 was required to maintain accessibility at specific enhancers associated with multiple oncogenes, and mFOXO1 degradation impaired RNA polymerase pause-release at some targets. Wild-type FOXO1 appeared to weakly regulate many of the same targets as mFOXO1 and was able to complement the degradation of mFOXO1 in the context of AKT inhibition.
转录失调是弥漫性大 B 细胞淋巴瘤（DLBCL）的一个标志，因为转录调节剂经常发生突变。然而，由于缺乏能够提供分离转录控制的直接和间接影响所需的时间分辨率的方法，我们对正常转录程序如何在 DLBCL 中被篡夺的机制理解受到了阻碍。我们应用了一种化学遗传学方法来设计转录因子 FOXO1 的诱导降解，该因子在 DLBCL 中经常发生突变（mFOXO1）。mFOXO1 的快速降解、新生转录本的检测以及染色质可及性的评估，使我们能够识别 mFOXO1 的直接靶标。mFOXO1 需要维持与多个癌基因相关的特定增强子的可及性，并且 mFOXO1 的降解会损害某些靶标处的 RNA 聚合酶暂停释放。野生型 FOXO1 似乎像 mFOXO1 一样弱调节许多相同的靶标，并且能够在 AKT 抑制的情况下补充 mFOXO1 的降解。
