Atherosclerosis (AS) is the most common type in cardiovascular disease. Due to its complex pathogenesis, the exact etiology of AS is unclear. circRNA has been shown to play an essential role in most diseases. However, the underlying mechanism of circRNA in AS has been not understood clearly. Quantitative Real-Time PCR assay was used to detect the expression of circRSF1, miR-135b-5p and histone deacetylase 1 (HDAC1). Western blot was applied to the measure of protein expression of HDAC1, B-cell lymphoma-2 (Bcl-2), BCL2-associated X (Bax), cleaved-caspase-3, vascular cell adhesion molecule 1 (VCAM1), intercellular cell adhesion molecule-1 (ICAM1) and E-selectin. MTT assay and flow cytometry were used to detect cell proliferation and apoptosis, respectively. Dual luciferase reporter assay and RIP assay was used to determine the relationship among circRSF1, miR-135b-5p and HDAC1. Besides, an ELISA assay was performed to measure the levels of IL-1β, IL-6, TNF-α and IL-8. In this study, ox-LDL inhibited circRSF1 and HDAC1 expression while upregulated miR-135b-5p expression in Human umbilical vein endothelial cells (HUVECs). Importantly, ox-LDL could inhibit HUVECs growth. Moreover, promotion of circRSF1 or inhibition of miR-135b-5p induced cell proliferation while inhibited apoptosis and inflammation of ox-LDL-treated HUVECs, which was reversed by upregulating miR-135b-5p or downregulating HDCA1 in ox-LDL-treated HUVECs. More than that, we verified that circRSF1 directly targeted miR-135b-5p and HDAC1 was a target mRNA of miR-135b-5p in HUVECs. CircRSF1 regulated ox-LDL-induced vascular endothelial cell proliferation, apoptosis and inflammation through modulating miR-135b-5p/HDAC1 axis in AS, providing new perspectives and methods for the treatment and diagnosis of AS.

中文翻译：

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CircRNA RSF1通过调节动脉粥样硬化中的miR-135b-5p/HDAC1轴来调节ox-LDL诱导的血管内皮细胞增殖、凋亡和炎症

动脉粥样硬化（AS）是心血管疾病中最常见的类型。由于其发病机制复杂，AS的确切病因尚不清楚。circRNA 已被证明在大多数疾病中发挥重要作用。然而，环状RNA在AS中的潜在机制尚不清楚。定量实时 PCR 检测用于检测 circRSF1、miR-135b-5p 和组蛋白去乙酰化酶 1 (HDAC1) 的表达。蛋白质印迹用于测量 HDAC1、B 细胞淋巴瘤 2 (Bcl-2)、BCL2 相关 X (Bax)、cleaved-caspase-3、血管细胞粘附分子 1 (VCAM1)、细胞间细胞的蛋白质表达粘附分子-1 (ICAM1) 和 E-选择素。MTT法和流式细胞仪分别用于检测细胞增殖和凋亡。双荧光素酶报告基因检测和RIP检测用于确定circRSF1、miR-135b-5p和HDAC1之间的关系。此外，进行ELISA测定以测量IL-1β、IL-6、TNF-α和IL-8的水平。在本研究中，ox-LDL 抑制 circRSF1 和 HDAC1 表达，同时上调人脐静脉内皮细胞 (HUVECs) 中 miR-135b-5p 的表达。重要的是，ox-LDL 可以抑制 HUVECs 的生长。此外，促进 circRSF1 或抑制 miR-135b-5p 可诱导细胞增殖，同时抑制 ox-LDL 处理的 HUVECs 的细胞凋亡和炎症，这可通过上调 miR-135b-5p 或下调 ox-LDL 处理的 HUVECs 中的 HDCA1 来逆转。不仅如此，我们还证实了 circRSF1 直接靶向 miR-135b-5p，而 HDAC1 是 HUVECs 中 miR-135b-5p 的靶 mRNA。