Thyagarajan Narmadaa, Marshall Jenika D, Pickett Arthur T, Schumacher Clemens, Yang Yanbo, Christian Sherri L, Brown Robert J
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.
Lipids. 2017 Mar;52(3):189-205. doi: 10.1007/s11745-017-4238-1. Epub 2017 Feb 15.
Macrophage lipoprotein lipase (LPL) induces lipid accumulation and promotes atherosclerosis. However, the effects of lipoprotein hydrolysis products generated by LPL on macrophage-derived foam cell formation are not clearly understood. Thus, we analyzed the transcriptomic response to hydrolysis products via microarray analyses on RNA isolated from human THP-1 macrophages incubated with total lipoprotein hydrolysis products generated by LPL. The expression of 183 transcripts was significantly upregulated and 133 transcripts were significantly downregulated. Bioinformatics analyses revealed that there was a significant over-representation of genes involved in cell cycling, stress response, type I interferon signaling, cellular metal ion homeostasis, sterol metabolism, and nuclease activity. Interestingly, transcripts for 63 small nucleolar RNA were significantly upregulated. We verified the microarray data by quantitative real-time PCR and found that the expression of SNORA56, as well as the expression of genes associated with the cell cycle (PCNA and DKC1 variant 3), stress response (ATF3), type I interferon signaling (IFITM1), and lipid metabolism (CD36 and PLIN2) were significantly affected by LPL hydrolysis products. To determine if the free fatty acid (FFA) component of total lipoprotein hydrolysis products is sufficient to alter the expression of these genes, THP-1 macrophages were also incubated with the total FFA or individual classes of the FFA component. The gene regulation by the FFA component did not mimic that of the hydrolysis products, suggesting that the regulation of gene expression in THP-1 macrophages depends on the specific combination and concentration of lipid species present in the hydrolysis products, and not solely on FFA.
巨噬细胞脂蛋白脂肪酶（LPL）可诱导脂质蓄积并促进动脉粥样硬化。然而，LPL产生的脂蛋白水解产物对巨噬细胞源性泡沫细胞形成的影响尚不清楚。因此，我们通过对从与LPL产生的总脂蛋白水解产物孵育的人THP-1巨噬细胞中分离的RNA进行微阵列分析，来分析对水解产物的转录组反应。183个转录本的表达显著上调，133个转录本显著下调。生物信息学分析表明，参与细胞周期、应激反应、I型干扰素信号传导、细胞金属离子稳态、甾醇代谢和核酸酶活性的基因存在显著的过度表达。有趣的是，63个小核仁RNA的转录本显著上调。我们通过定量实时PCR验证了微阵列数据，发现SNORA56的表达以及与细胞周期相关的基因（PCNA和DKC1变体3）、应激反应（ATF3）、I型干扰素信号传导（IFITM1）和脂质代谢（CD36和PLIN2）的表达均受到LPL水解产物的显著影响。为了确定总脂蛋白水解产物中的游离脂肪酸（FFA）成分是否足以改变这些基因的表达，THP-1巨噬细胞也与总FFA或FFA成分的各个类别进行孵育。FFA成分对基因的调控并未模拟水解产物的调控，这表明THP-1巨噬细胞中基因表达的调控取决于水解产物中脂质种类的特定组合和浓度，而不仅仅取决于FFA。
