Yu Hong, Hong Jialing, Wang Binghua, Peng Fangfang, Li Xiaoming, He Chunyan
Department of Biochemistry and Molecular Biology, School of Medicine, Wuhan University, Wuhan 430071, China.
Chin Med J (Engl). 2003 May;116(5):721-6.
To assess the atherogenicity of lipoprotein(a), the effect of the heterogeneity of lysine binding of apolipoprotein(a) [apo(a)], a plasminogen-like glycoprotein component on the proliferation of human arterial smooth muscle cells (SMCs).
Both wild type (wt) Trp72 and mutant (mut) Trp72-->Arg forms of apo(a) kringle IV-10 were expressed by employing a GST-gene fusion system into E. coli. The proliferation of SMCs was determined by flow cytometry and MTT colorimetry. Enzyme-linked immunosorbent assay (ELISA) assay was used to detect the active form of transforming growth factor beta(1) (TGF-beta(1)).
Apo(a) wt-kringle IV-10 that has lysine binding properties possessed a growth-stimulating activity to SMCs on a dose-dependence manner by stimulating cells in the G(1)/G(0) phase of cell cycle to S and G(2)/M phase, and reduced significantly the amounts of endogenous active TGF-beta(1) in culture when compared with the control medium and the GST group (2.4 +/- 0.5 vs 8.6 +/- 1.6 and 9.1 +/- 1.7 ng/ml, P < 0.01). The growth-stimulating effect of apo(a) mut-kringle IV-10 deficient in lysine binding was negligible.
Apo(a) induces SMCs growth by inhibiting the activation of latent TGF-beta(1), an activity that may involve the ability of apo(a) kringle IV-10 to bind lysine. The mitogenic effect of apo(a) wt-kringle IV-10 on SMCs might play an active role in the atherogenic function of lipoprotein(a).
评估脂蛋白(a)的致动脉粥样硬化性，即载脂蛋白(a)[apo(a)，一种纤溶酶原样糖蛋白成分]赖氨酸结合异质性对人动脉平滑肌细胞(SMCs)增殖的影响。
采用GST-基因融合系统在大肠杆菌中表达野生型(wt)色氨酸72和突变型(mut)色氨酸72→精氨酸形式的apo(a)kringle IV-10。通过流式细胞术和MTT比色法测定SMCs的增殖。采用酶联免疫吸附测定(ELISA)法检测转化生长因子β(1)(TGF-β(1))的活性形式。
具有赖氨酸结合特性的apo(a)wt-kringle IV-10对SMCs具有剂量依赖性的生长刺激活性，可将细胞周期G(1)/G(0)期的细胞刺激至S期和G(2)/M期，与对照培养基和GST组相比，培养物中内源性活性TGF-β(1)的含量显著降低(2.4±0.5 vs 8.6±1.6和9.1±1.7 ng/ml，P<0.01)。缺乏赖氨酸结合能力的apo(a)mut-kringle IV-10的生长刺激作用可忽略不计。
apo(a)通过抑制潜在TGF-β(1)的激活来诱导SMCs生长，该活性可能与apo(a)kringle IV-10结合赖氨酸的能力有关。apo(a)wt-kringle IV-10对SMCs的促有丝分裂作用可能在脂蛋白(a)的致动脉粥样硬化功能中发挥积极作用。
