Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America.
PLoS One. 2019 May 2;14(5):e0216203. doi: 10.1371/journal.pone.0216203. eCollection 2019.
Transcription factor RUNX1 and its binding partner CBFβ play a critical role in gene regulation for hematopoiesis. Mutations of RUNX1 cause ~10% of acute myeloid leukemia (AML) with a particularly poor prognosis. The current paradigm for the leukemogenesis is that insufficient activity of wild-type (WT) RUNX1 impairs hematopoietic differentiation. The majority of mutant RUNX1 proteins lose the DNA-binding affinity and inhibit WT RUNX1 by depletion of CBFβ. Here, isothermal titration calorimetry (ITC) was used to quantitatively study the interactions of WT and three clinical mutant RUNX1, CBFβ and DNA. Our data show that the binding of RUNX1 to DNA is enthalpy-driven, and the affinity decreases in the order of WT > S114L > R139Q >> K83E, which support previous observations and conclusion. To find potentially beneficial RUNX1 mutations that could increase the overall RUNX1 activity, K83R and H179K mutations of RUNX1 were designed, using structure-based computational modeling, and found to possess significantly higher DNA-binding affinities than does WT RUNX1. K83R and H179K mutant RUNX1 could therefore be protein-based RUNX1 activators.
转录因子 RUNX1 及其结合伴侣 CBFβ 在造血的基因调控中发挥着关键作用。RUNX1 的突变导致约 10%的急性髓系白血病 (AML)，预后特别差。目前的白血病发生模型认为，野生型 (WT) RUNX1 的活性不足会损害造血分化。大多数突变的 RUNX1 蛋白失去 DNA 结合亲和力，并通过耗尽 CBFβ 来抑制 WT RUNX1。在这里，使用等温滴定量热法 (ITC) 定量研究了 WT 和三种临床突变型 RUNX1、CBFβ 和 DNA 的相互作用。我们的数据表明，RUNX1 与 DNA 的结合是焓驱动的，亲和力的顺序为 WT > S114L > R139Q >> K83E，这支持了先前的观察和结论。为了寻找可能增加整体 RUNX1 活性的有益 RUNX1 突变，我们使用基于结构的计算建模设计了 RUNX1 的 K83R 和 H179K 突变，发现它们比 WT RUNX1 具有更高的 DNA 结合亲和力。因此，K83R 和 H179K 突变型 RUNX1 可以作为基于蛋白质的 RUNX1 激活剂。
