Expression of the human apolipoprotein A-I: polymorphisms and drug effects

在载脂蛋白基因分析过程中，我们在日本高甘油三酯血症患者中发现了APOA5基因c.553G>T多态性。这种多态性导致半胱氨酸取代甘氨酸的氨基酸变化。用限制性片段长度多态性法测定了95例日本高甘油三酯血症患者和119例无血缘关系的正常血脂患者的-1131T>C和- 553g >T多态性的频率。高甘油三酯血症患者T等位基因-1131bp（0.511）和c.553G>T等位基因（0.205）的频率显著高于正常血脂组（0.315和0.105），差异有统计学意义（p<0.01和p<0.02）。两个多态位点处于强烈的连锁不平衡状态。这些结果表明，多态性- 1131t> C和c553g >T与日本人群的高甘油三酯血症有关。他汀类药物治疗降低低密度脂蛋白胆固醇和甘油三酯的水平，并增加抗动脉粥样硬化HDL的水平。我们研究了它们调节APOA5基因表达的能力，从而影响血浆甘油三酯水平。APOA5基因启动子活性是通过检测转染人肝癌HepG2细胞的带有APOA5启动子区的质粒的荧光素酶活性来估计的。匹伐他汀显著提高了人HepG2细胞中APOA5的表达和mRNA水平，同时转染PPARa可显著提高APOA5的表达。这些作用被加入甲羟戊酸或焦磷酸香叶基香叶基逆转，暗示HMG-CoA还原酶是这些药物的相关靶点。

In course of apolipoprotein genes analysis, we found a polymorphism of APOA5 gene, c.553G>T in Japanese patients with hypertriglyceridemia. This polymorphism causes the change of amino acid substitution of a cysteine for a glycine. The frequencies of -1131T>C and c.553G>T polymoiphisms in 95 Japanese patients with hypertriglyceridemia and 119 unrelated normolipidemic subjects were determined by restriction-fragment-length-polymorphisms. The frequencies of the T allele at -1131bp (0.511) and the t allele at c.553G>T (0.205) in patients with hypertriglyceridemia were significantly higher than those in normolipidemic subjects (0.315 and 0.105), respectively (p<0.01and p<0.02). The two polymorphic sites were in strong linkage disequilibrium. These results suggest that the polymorphisms, -1131T>C and c.553G>T were associated with hypertriglyceridemia in Japanese population. Statin treatment reduces the levels of LDL cholesterol and triglyceride, and increases the levels of the antiatherogenic HDL. We investigated their ability to modulate APOA5 gene expression and consequently influence plasma triglyceride levels. Promoter activity of the APOA5 gene was estimated by measuring luciferase activity of plasmids with a APOA5 promoter region transfected into human hepatoma HepG2 cells. Treatment with pitavastatin significantly increased APOA5 expression and mRNA levels in human HepG2 cells, and cotransfection of a PPARa treatment resulted in a significant increase of APOA5 expression. These effects were reversed by the addition of mevalonate or geranylgeranyl pyrophosphate, implicating HMG-CoA reductase as the relevant target of these drugs.