Berge K E, Djurovic S, Muller H J, Alestrøm P, Berg K
Institute of Medical Genetics, University of Oslo, Department of Medical Genetics, Ullevål University Hospital, Norway.
Clin Genet. 1997 Nov;52(5):314-25. doi: 10.1111/j.1399-0004.1997.tb04349.x.
The reason(s) for the atherogenic properties of Lp(a) lipoprotein is still unclear, and several mechanisms have been studied. Alterations in gene expression in endothelial cells (ECs) could be important with respect to risk for coronary heart disease (CHD). We have tested the effects of Lp(a) lipoprotein or the apolipoprotein of Lp(a) lipoprotein (apo(a)) on cultured human umbilical vein endothelial cells (HUVECs) with respect to: (1) the level of endothelin-1 (ET-1) mRNA; (2) release of ET-1 into the culture medium; (3) plasminogen activator inhibitor-1 (PAI-1) secretion into the culture medium and; (4) total gene expression in HUVECs, examined by a polymerase chain reaction (PCR)-based technique, differential display-reverse transcription-PCR (DD-RT-PCR). Lp(a) lipoprotein reduced the level of ET-1 mRNA as well as the release of ET-1. The reduction of ET-1 in the medium was even more pronounced when HUVECs were incubated with apo(a), but we found no effect of apo(a) on ET-1 mRNA level. Neither Lp(a) lipoprotein nor apo(a) had a significant influence on PAI-1 secretion. DD-RT-PCR revealed 11 fragments that could represent differences between cells exposed or not exposed to Lp(a) lipoprotein. Following subcloning and sequencing, 18 sequences that differed between exposed and unexposed cultures were obtained. Four of the subcloned fragments have up to now been used as a probe for northern blot analyses, and one fragment was confirmed to be regulated by Lp(a) lipoprotein. In conclusion, Lp(a) lipoprotein is shown to control ET-1 mRNA levels and the function of at least one more gene, the nature of which is unknown.
脂蛋白(a)[Lp(a)]致动脉粥样硬化的机制仍不清楚，目前已有多种机制被研究。内皮细胞(ECs)基因表达的改变可能是冠心病(CHD)风险的重要因素。我们测试了Lp(a)脂蛋白或Lp(a)脂蛋白的载脂蛋白[载脂蛋白(a)，apo(a)]对培养的人脐静脉内皮细胞(HUVECs)的影响，具体如下：(1)内皮素-1(ET-1)mRNA水平；(2)ET-1释放到培养基中的情况；(3)纤溶酶原激活物抑制剂-1(PAI-1)分泌到培养基中的情况；(4)通过基于聚合酶链反应(PCR)的技术——差异显示逆转录PCR(DD-RT-PCR)检测HUVECs中的总基因表达。Lp(a)脂蛋白降低了ET-1 mRNA水平以及ET-1的释放。当HUVECs与apo(a)一起孵育时，培养基中ET-1的降低更为明显，但我们发现apo(a)对ET-1 mRNA水平没有影响。Lp(a)脂蛋白和apo(a)对PAI-1分泌均无显著影响。DD-RT-PCR显示有11个片段可能代表暴露于或未暴露于Lp(a)脂蛋白的细胞之间的差异。经过亚克隆和测序，获得了18个在暴露和未暴露培养物之间存在差异的序列。目前，其中4个亚克隆片段已被用作Northern印迹分析的探针，并且有1个片段被证实受Lp(a)脂蛋白调控。总之，研究表明Lp(a)脂蛋白可控制ET-1 mRNA水平以及至少一个其他基因的功能，该基因的性质尚不清楚。
