Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
Nucleic Acids Res. 2022 Aug 26;50(15):8700-8718. doi: 10.1093/nar/gkac645.
FACT (FAcilitates Chromatin Transcription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated in both epithelial and natural killer (NK) cells. The histone acetyltransferase TIP60 contributes to the acetylation of SUPT16H middle domain (MD) at lysine 674 (K674). Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H in both epithelial and NK cells. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (HDAC1, EZH2), and further regulates their activation status and/or promoter association as well as affects the relevant histone marks (H3ac, H3K9me3 and H3K27me3). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, depletion or inhibition of SUPT16H is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that depletion or inhibition of SUPT16H also causes the remarkable activation of IFN signaling in NK cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in coordinating with BRD4 and regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of the FACT inhibitor CBL0137 to treat viral infections.
FACT（促进染色质转录）是一种由 SUPT16H 和 SSRP1 组成的异二聚体蛋白复合物，是一种参与基因转录过程中染色质重塑的组蛋白伴侣。FACT 复合物受到深刻的调控，参与基因激活和抑制。在这里，我们报道 SUPT16H，FACT 的一个亚基，在上皮细胞和自然杀伤 (NK) 细胞中都被乙酰化。组蛋白乙酰转移酶 TIP60 有助于 SUPT16H 中域 (MD) 赖氨酸 674 (K674) 的乙酰化。这种 SUPT16H 的乙酰化被溴结构域蛋白 BRD4 识别，促进了 SUPT16H 在上皮细胞和 NK 细胞中的蛋白质稳定性。我们进一步证明，SUPT16H-BRD4 与组蛋白修饰酶 (HDAC1、EZH2) 相关联，并进一步调节它们的激活状态和/或启动子关联，以及影响相关的组蛋白标记 (H3ac、H3K9me3 和 H3K27me3)。BRD4 被认为可以深刻调节干扰素 (IFN) 信号，而 SUPT16H 的这种功能从未被探索过。令人惊讶的是，我们的结果表明，通过 RNAi 敲低 SUPT16H 或使用其抑制剂 curaxin 137 (CBL0137) 进行药理学抑制，会导致 IFN 和干扰素刺激基因 (ISGs) 的诱导。通过这种机制，耗尽或抑制 SUPT16H 可以有效地抑制多种病毒的感染，包括寨卡病毒、流感病毒和 SARS-CoV-2。此外，我们还证明，耗尽或抑制 SUPT16H 也会导致 NK 细胞中 IFN 信号的显著激活，这促进了人原代 NK 细胞共培养系统中病毒感染细胞的 NK 介导杀伤。总的来说，我们的研究揭示了 FACT 复合物在与 BRD4 协调并调节上皮细胞和 NK 细胞中的 IFN 信号方面的先前未被认识的作用，并提出了 FACT 抑制剂 CBL0137 治疗病毒感染的新应用。
