Mid-Germany Heart Center, Division of Cardiology, Angiology, and Intensive Medical Care, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Straße 40, 06120 Halle, Germany.
Department of Cardiology and Angiology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
Cardiovasc Res. 2021 Feb 22;117(3):850-862. doi: 10.1093/cvr/cvaa121.
Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo.
Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice.
Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.
最近的研究表明，溴结构域和末端（BET）表观遗传读蛋白类似于癌症、糖尿病或心血管疾病基础病理生理学的关键调节剂。然而，它们是否也通过对血管细胞的直接作用来调节血管重塑过程尚不清楚。在这项研究中，我们研究了 BET 蛋白对体外人平滑肌细胞（SMC）功能的影响以及体内血管损伤后新生内膜形成的影响。
小分子（+）-JQ1 对 BET 的选择性抑制可剂量依赖性地降低 SMC 的增殖和迁移，而无凋亡或毒性作用。流式细胞术分析显示，（+）-JQ1 存在时细胞周期停滞在 G0/G1 期。微阵列和通路分析显示，FOXO1 转录因子控制的基因集的转录调控发生了实质性变化。沉默受调控最显著的 FOXO1 依赖性基因 CDKN1A，可消除抗增殖作用。免疫组织化学共定位、共免疫沉淀和启动子结合 ELISA 检测数据证实，BET 蛋白 BRD4 可直接与 FOXO1 结合并调节 FOXO1 转录激活能力。在体内，局部应用（+）-JQ1 可显著抑制 C57BL/6 小鼠股动脉丝诱导损伤后 SMC 增殖和新生内膜形成。
血管损伤后（+）-JQ1 抑制 BET 蛋白 BRD4 可恢复 FOXO1 转录激活活性，随后 CDKN1A 表达、细胞周期停滞，从而防止体外 SMC 增殖和体内新生内膜形成。因此，抑制 BET 表观遗传读蛋白可能是预防不良血管重塑的一种有前途的治疗策略。
