藥物對變異型脂蛋白解脂酶活性之影響

脂蛋白解脂酶 (LPL) 在脂質代謝方面佔有重要的角色，其主要的功能在於水解乳糜微粒和極低密度脂蛋白中的三酸甘油酯。三酸甘油酯經脂蛋白解脂酶分解會形成游離型脂肪酸及甘油，而游離型脂肪酸可燃燒作為能量使用，或者以脂肪形式貯存。當脂蛋白解脂酶發生變異時會造成第一型高脂血症，脂質的代謝會失去平衡。本實驗室在先前的研究中，從台灣地區高三酸甘油酯血症病人血液中發現了脂蛋白解脂酶兩處基因突變，分別是在第252位置的白胺酸變成精胺酸和纈胺酸。這兩處基因的突變皆會造成高三酸甘油酯血症。為了想治療這兩處的基因突變造成的高三酸甘油酯血症，擬建構包含人類脂蛋白解脂酶啟動子序列及cDNA的質體，分別是野生型PLPLWT及突變型PLPL252R和PLPL252V，將這些質體分別轉染到人類293細胞後再藉由藥物（bezafibrate, ciprofibrate, fenofibrate, gemfibrozil, curcumin, esculetin）處理，觀察看是否能達到提高LPL活性及濃度之效用，藉以降低血中的三酸甘油酯。先利用藥物處理有轉染人類脂蛋白解脂酶啟動子序列之質體的人類293細胞，從這些細胞溶解物中發現啟動子下游的報導基因（β-galactosidase）之活性有明顯增加（P＜0.05），證實這些藥物確實可以作用在人類脂蛋白解脂酶啟動子上，促進下游基因的表現。之後同樣的再使用這些藥物處理PLPLWT質體，從實驗結果發現蛋白解脂酶的mRNA確實是存在細胞中，但卻無法偵測到脂蛋白解脂酶活性及濃度的變化，其原因可能是缺少人類脂蛋白解脂酶序列+80 ~ +144的片段，而影響脂蛋白解脂酶蛋白的生成。目前仍無法直接證明變異型脂蛋白解脂酶會受到藥物影響而提高LPL活性。未來若能重新建構一個包含完整脂蛋白解脂酶序列(-1715 ~ +1643)的質體即能對藥物的功能做更進一步探討。

關鍵字

脂蛋白解脂酶高三酸甘油酯血症；核受體；藥物；活性

並列摘要

Lipoprotein lipase ( LPL ) plays an important role in the metabolism of plasma lipid metabolism. It catalyzes the hydrolysis of triglycerides from chylomicrons and very low density lipoprotein into glycerol, diacylglycerol and free fatty acids and the free fatty acids are supplied to tissues as sources of metabolic energy or stored as triglycerides after re-esterification. The defect in LPL gene can cause type I hyperlipoproteinemia and affect lipid homeostasis. In our previous study, the substitution of leucine for valine or arginine at amino acid residue 252 of LPL was found in hyperlipoproteinemic Taiwanese. Both mutated sites at LPL caused hyperlipoproteinemia. We constructed plasmids carrying either LPL promoter and wild type cDNA ( PLPLWT ) or mutated type cDNA ( PLPL252R, PLPL252V ) and transfected these plasmids into HEK293 cells. The aim of this study was to investigate whether drugs（bezafibrate, ciprofibrate, fenofibrate, gemfibrozil）or chemicals （curcumin, esculetin）could increase LPL activity and concentration in transfected cells. We observed significant expression of reporter gene（β-galactosidase）（P＜0.05） in drugs-treated cells transfected with plasmid carrying human LPL promoter. Although mRNA of LPL was expressed in drugs-treated cells transfected with PLPLWT plasmid, the LPL activity and mass in culture medium were not detected. The reason may be the lack of +80 ~ +144 sequence. According to this result, we could not suggest that drugs increase LPL expression. In the future, we should construct new plasmid containing -1715 ~ +1643 sequence. It is helpful for advanced study about effects of drugs.

並列關鍵字

lipoprotein lipase ； hypertriglyceridemia ； nuclear receptor ； drug ； activity

參考文獻

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藥物對變異型脂蛋白解脂酶活性之影響

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