Department of Respiratory and Critical Care Medicine, The Second Xiangya Hospital, Hunan Centre for Evidence-Based Medicine, Central South University, Changsha, Hunan, China.
Department of Hematology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
Aging (Albany NY). 2021 Apr 26;13(9):13179-13194. doi: 10.18632/aging.203000.
Better understanding of the transcriptional regulatory network in acute promyelocytic leukemia (APL) cells is critical to illustrate the pathogenesis of other types of acute myeloid leukemia. Previous studies have primarily focused on the retinoic acid signaling pathway and how it is interfered with by promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion protein. However, this hardly explains how APL cells are blocked at the promyelocytic stage. Here, we demonstrated that C/EBPα bound and transactivated the promoter of long non-coding RNA NEAT1, an essential element for terminal differentiation of APL cells, through C/EBP binding sites. More importantly, PML/RARα repressed C/EBPα-mediated transactivation of NEAT1 through binding to NEAT1 promoter. Consistently, mutation of the C/EBP sites or deletion of retinoic acid responsive elements (RAREs) and RARE half motifs abrogated the PML/RARα-mediated repression. Moreover, silencing of C/EBPα attenuated ATRA-induced NEAT1 upregulation and APL cell differentiation. Finally, simultaneous knockdown of C/EBPα and C/EBPβ reduces ATRA-induced upregulation of C/EBPε and dramatically impaired NEAT1 activation and APL cell differentiation. In sum, C/EBPα binds and transactivates NEAT1 whereas PML/RARα represses this process. This study describes an essential role for C/EBPα in PML/RARα-mediated repression of NEAT1 and suggests that PML/RARα could contribute to the pathogenesis of APL through suppressing C/EBPα targets.
更好地理解急性早幼粒细胞白血病(APL)细胞中的转录调控网络对于阐明其他类型急性髓性白血病的发病机制至关重要。以前的研究主要集中在维甲酸信号通路及其如何被早幼粒细胞白血病/维甲酸受体-α(PML/RARα)融合蛋白干扰。然而,这很难解释 APL 细胞如何在早幼粒细胞阶段被阻断。在这里,我们通过 C/EBP 结合位点证明 C/EBPα 结合并反式激活长非编码 RNA NEAT1 的启动子,NEAT1 是 APL 细胞终末分化的必需元件。更重要的是,PML/RARα 通过结合 NEAT1 启动子抑制 C/EBPα 介导的 NEAT1 反式激活。一致地,C/EBP 位点的突变或维甲酸反应元件(RAREs)和 RARE 半基序的缺失消除了 PML/RARα 介导的抑制作用。此外,沉默 C/EBPα 减弱了 ATRA 诱导的 NEAT1 上调和 APL 细胞分化。最后,同时敲低 C/EBPα 和 C/EBPβ 减少了 ATRA 诱导的 C/EBPε 的上调,并显著损害了 NEAT1 的激活和 APL 细胞分化。总之,C/EBPα 结合并反式激活 NEAT1,而 PML/RARα 抑制此过程。这项研究描述了 C/EBPα 在 PML/RARα 介导的 NEAT1 抑制中的重要作用,并表明 PML/RARα 可能通过抑制 C/EBPα 靶标导致 APL 的发病机制。