Cola Clarissa, Almeida Maria, Li Dayuan, Romeo Francesco, Mehta Jawahar L
Departments of Internal Medicine and Physiology and Biophysics, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare System, Little Rock, AR, USA.
Biochem Biophys Res Commun. 2004 Jul 23;320(2):424-7. doi: 10.1016/j.bbrc.2004.05.181.
Vascular calcification is a highly regulated process sharing features of bone mineralization. Since endothelium regulates many of the processes during atherogenesis, we monitored the expression of genes involved in calcification upon exposure of human coronary artery endothelial cells (HCAECs) to atherogenic stimuli. Genes studied were: core binding factor alpha-1 (Cbfa1/Runx2), a pivotal transcriptional regulator of osteogenesis; bone morphogenetic protein-2 (BMP2), an inducer of cartilage and bone; and matrix gla-protein (MGP), a potent inhibitor of calcification, which exerts its action by blocking BMP2. HCAECs were treated with oxidized-low density lipoprotein (ox-LDL, 80 microg/mL) or tumor necrosis factor-alpha (TNFalpha, 10 ng/mL), and the expression of Cbfa1, BMP2, and MGP was quantified by real-time PCR. Cbfa1 was expressed at low levels in untreated HCAECs, and its expression did not change with ox-LDL or TNFalpha treatment. The expression of BMP2 and MGP increased early after exposure to ox-LDL or TNFalpha (at 2-8 h), and the increase was not evident at 24 h. Ox-LDL exerted a stronger effect on MGP than on BMP2 expression. The effects of ox-LDL, but not TNFalpha, on MGP and BMP2 expression were inhibited by pretreatment of cells with an antibody directed at LOX-1, a lectin-like receptor for ox-LDL (10 microg/mL). Thus, the endothelium, when exposed to atherogenic stimuli, ox-LDL in particular, regulates the process of calcification by enhancing the expression of the bone inhibitory MGP, while the expression of Cbfa1 remains unchanged. Upregulation of BMP2 may represent a feedback upregulation in response to increase in MGP. The effect of ox-LDL appears to be mediated by LOX-1 activation.
血管钙化是一个高度受调控的过程，具有骨矿化的特征。由于内皮细胞在动脉粥样硬化形成过程中调节许多过程，我们监测了人冠状动脉内皮细胞（HCAECs）暴露于动脉粥样硬化刺激后参与钙化的基因表达。研究的基因包括：核心结合因子α-1（Cbfa1/Runx2），一种成骨的关键转录调节因子；骨形态发生蛋白-2（BMP2），软骨和骨的诱导剂；以及基质γ-羧基谷氨酸蛋白（MGP），一种有效的钙化抑制剂，它通过阻断BMP2发挥作用。用氧化型低密度脂蛋白（ox-LDL，80μg/mL）或肿瘤坏死因子-α（TNFα，10ng/mL）处理HCAECs，并通过实时PCR定量Cbfa1、BMP2和MGP的表达。Cbfa1在未处理的HCAECs中低水平表达，其表达在ox-LDL或TNFα处理后没有变化。暴露于ox-LDL或TNFα后早期（2-8小时）BMP2和MGP的表达增加，在24小时时增加不明显。ox-LDL对MGP表达的影响比对BMP2表达的影响更强。用针对ox-LDL的凝集素样受体LOX-1的抗体（10μg/mL）预处理细胞可抑制ox-LDL对MGP和BMP2表达的影响，但不抑制TNFα的影响。因此，内皮细胞在暴露于动脉粥样硬化刺激特别是ox-LDL时，通过增强骨抑制性MGP的表达来调节钙化过程，而Cbfa1的表达保持不变。BMP2的上调可能代表对MGP增加的反馈上调。ox-LDL的作用似乎是由LOX-1激活介导的。
