Singh Neetu, Ramĩrez-Carvajal Lisbeth, de Los Santos Teresa, Golding Michael C, Long Charles R
1 Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University , College Station, Texas.
2 Oak Ridge Institute for Science and Education (ORISE)-Plum Island Animal Disease Center (PIADC) Research Participation Program , Oak Ridge, Tennessee.
J Interferon Cytokine Res. 2016 Jan;36(1):37-47. doi: 10.1089/jir.2015.0006. Epub 2015 Sep 29.
The genetic regulatory network controlling the innate immune system is well understood in many species. However, the role of the epigenetic mechanisms underlying the expression of immunoregulatory genes is less clear, especially in livestock species. Histone H3 lysine 9 dimethylation (H3K9me2) is an epigenetic modification associated with transcriptional silencing within the euchromatin regions. Euchromatic histone-lysine N-methyltransferase 2 (EHMT2; also known as G9a) is a crucial enzyme responsible for regulating the dynamics of this epigenetic modification. It has been shown that histone modifications play a role in regulating type I interferon (IFN) response. In the present study, we investigated the role of EHMT2 in the epigenetic regulation of bovine antiviral innate immunity and explored its therapeutic potential against viral infections. We evaluated the effects of pharmacological and RNAi-mediated inhibition of EHMT2 on the transcription of IFN-β and other IFN-inducible antiviral genes, as well as its effect on foot-and-mouth disease virus (FMDV) and vesicular stomatitis virus (VSV) replication in bovine cells. We show that treatment of primary bovine cells with the synthetic EHMT2 inhibitor (UNC0638) either before or shortly after virus infection resulted in a significant increase in transcript levels of bovine IFN-β (boIFN-β; 300-fold) and other IFN-inducible genes, including IFN-stimulated gene 15 (ISG-15), myxovirus resistance 1 (Mx-1), Mx-2, RIG-I, 2',5'-oligoadenylate synthetase 1 (OAS-1), and protein kinase R (PKR). Expression of these factors correlated with a significant decrease in VSV and FMDV viral titers. Our data confirm the involvement of EHMT2 in the epigenetic regulation of boIFN-β and demonstrate the activation of a general antiviral state after EHMT2 inhibition.
在许多物种中，控制先天免疫系统的基因调控网络已被充分了解。然而，免疫调节基因表达背后的表观遗传机制的作用尚不清楚，尤其是在牲畜物种中。组蛋白H3赖氨酸9二甲基化（H3K9me2）是一种与常染色质区域内转录沉默相关的表观遗传修饰。常染色质组蛋白赖氨酸N-甲基转移酶2（EHMT2；也称为G9a）是负责调节这种表观遗传修饰动态的关键酶。研究表明，组蛋白修饰在调节I型干扰素（IFN）反应中发挥作用。在本研究中，我们研究了EHMT2在牛抗病毒先天免疫表观遗传调控中的作用，并探索了其对病毒感染的治疗潜力。我们评估了药物和RNAi介导的EHMT2抑制对IFN-β和其他IFN诱导的抗病毒基因转录的影响，以及其对牛细胞中口蹄疫病毒（FMDV）和水疱性口炎病毒（VSV）复制的影响。我们发现，在病毒感染前或感染后不久用合成的EHMT2抑制剂（UNC0638）处理原代牛细胞，会导致牛IFN-β（boIFN-β；300倍）和其他IFN诱导基因的转录水平显著增加，包括IFN刺激基因15（ISG-15）、抗黏液病毒1（Mx-1）、Mx-2、视黄酸诱导基因I（RIG-I）、2',5'-寡腺苷酸合成酶1（OAS-1）和蛋白激酶R（PKR）。这些因子的表达与VSV和FMDV病毒滴度的显著降低相关。我们的数据证实了EHMT2参与了boIFN-β的表观遗传调控，并证明了EHMT2抑制后会激活一般抗病毒状态。
