Atherosclerosis is associated with deregulated cholesterol metabolism and formation of macrophage foam cells. CCAAT/enhancer-binding protein beta (C/EBPβ) is a transcription factor, and its inhibition has recently been shown to prevent atherosclerosis development and foam cell formation. However, whether C/EBPβ regulates inflammation, endoplasmic reticulum (ER) stress, and apoptosis, in macrophage foam cells and its underlying molecular mechanism remains unknown. Here, we investigated the effect of C/EBPβ knockdown on proteins and genes implicated in inflammation, ER stress, apoptosis, and autophagy in macrophage foam cells. RAW264.7 macrophage cells were transfected with control and C/EBPβ-siRNA and then treated with nLDL and oxLDL. Key proteins and genes involved in inflammation, ER stress, apoptosis, and autophagy were analyzed by western blot and qPCR. We found that short interfering RNA (siRNA)-mediated knockdown of C/EBPβ attenuated atherogenic lipid-mediated induction of proteins and genes implicated in inflammation (P-NFkB-p65, NFkB-p65, and TNFα), ER stress (ATF4 and ATF6), and apoptosis (CHOP, caspase 1, 3, and 12). Interestingly, C/EBPβ knockdown upregulated the expression of autophagy proteins (LC3A/B-II, ATG5) and genes (LC3B, ATG5) but decreased the mammalian target of rapamycin (mTOR) protein phosphorylation and mTORC1 gene expression in oxLDL-loaded RAW264.7 macrophage cells. More importantly, treatment with rapamycin (inhibitor of mTOR) increased expression of proteins implicated in autophagy and cholesterol efflux in oxLDL-loaded RAW 264.7 macrophage cells. The present results suggest that C/EBPβ inactivation regulates macrophage foam cell formation in atherogenesis by reducing inflammation, ER stress, and apoptosis and by promoting autophagy and inactivating mTOR.

中文翻译：

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CCAAT /增强子结合蛋白β（C /EBPβ）组合物可减少炎症，内质网应激和凋亡，并促进经oxLDL处理的RAW264.7巨噬细胞的自噬。

动脉粥样硬化与胆固醇代谢失调和巨噬细胞泡沫细胞形成有关。CCAAT /增强子结合蛋白β（C /EBPβ）是一种转录因子，最近已显示其抑制作用可防止动脉粥样硬化的发展和泡沫细胞的形成。然而，C /EBPβ是否调节巨噬细胞泡沫细胞中的炎症，内质网（ER）应激和凋亡及其潜在的分子机制尚不清楚。在这里，我们研究了C /EBPβ基因敲低对涉及巨噬细胞泡沫细胞中炎症，内质网应激，细胞凋亡和自噬的蛋白质和基因的影响。用对照和C /EBPβ-siRNA转染RAW264.7巨噬细胞，然后用nLDL和oxLDL处理。与炎症，内质网应激，细胞凋亡，通过Western blot和qPCR分析自噬和自噬。我们发现，短干扰RNA（siRNA）介导的C /EBPβ的敲低减弱了动脉粥样硬化脂质介导的与炎症相关的蛋白质和基因（P-NFkB-p65，NFkB-p65和TNFα），内质网应激（ATF4和ATF6）的诱导）和凋亡（CHOP，caspase 1、3和12）。有趣的是，C /EBPβ敲低可上调自噬蛋白（LC3A / B-II，ATG5）和基因（LC3B，ATG5）的表达，但降低了载有oxLDL的RAW264中雷帕霉素（mTOR）蛋白磷酸化和mTORC1基因表达的哺乳动物靶点。 7个巨噬细胞。更重要的是，在载有oxLDL的RAW 264.7巨噬细胞中，雷帕霉素（mTOR抑制剂）治疗可增加涉及自噬和胆固醇外排的蛋白质表达。