篇名 | 載脂蛋白 apo-VLDL-II 影響雞隻極低密度脂蛋白粒徑與組成 |
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卷期 | 46增刊 |
並列篇名 | Apo VLDL-II affects VLDL particle size and composition in laying hens |
作者 | 葉宥麟 、 鍾正玗 、 陳洵一 |
頁次 | 090-090 |
關鍵字 | 輔脂蛋白apoVLDL-II 、 極低密度脂蛋白 、 粒徑分佈 、 蛋雞 、 MTP 、 ApoVLDL-II 、 VLDL 、 Particle diameter 、 Laying hens 、 MTP |
出刊日期 | 201712 |
鳥類產蛋期時,血漿中出現較小粒徑 VLDL 顆粒(VLDLy),此粒徑的改變被證實能便利 VLDLy 通過濾泡內各層藩籬,最後被攝入形成蛋黃。因 apoVLDL-II 與較小粒徑同時發生在 產蛋期 VLDL 上,故 apoVLDL-II 一直被猜測是導致 VLDL 較小粒徑的主因。然一直沒有 直接的證據,因此本研究為證明 apo VLDL-II 是否影響 VLDLy 粒徑。以小雞初代肝臟細胞, 經轉染 apo VLDL-II 基因後,apo VLDL-II 大量分泌至培養液中,而在 oleate 刺激下,其分 泌 TG(triacylglycerol)隨劑量遞增。外源性 estradiol 處理與 apo VLDL-II 過度表達 (overexpression)皆會刺激肝細胞 TG 分泌,且會增強 oleate 所誘發 TG 分泌。培養液中 分離出 VLDL,以電子顯微鏡觀察下,apo VLDL-II 過度表達的確會導致 VLDL 粒徑變小。 而 apo VLDL-II overexpression 與 oleate 刺激皆會增強 MTP(microsomal transfer protein)表 現,此意味 apo VLDL-II 可能影響雞隻肝細胞內脂質可運用性,進而影響 VLDL 合成與分泌, 並導致產蛋期 VLDL 粒徑與 lipid 組成的改變。
Plasma VLDL biology in laying hens differs distinctively from that of immature hens, including a smaller VLDL particle diameter, dramatic increases of actual and fractional of levels of VLDL-TG (triacylglycerol) concentration, and the presence of an avian specific apolipoprotein; VLDL-II (apoVLDL-II). Despite lacking direct evidences, due to the presence of apoVLDL-II in VLDLy simultaneously with smaller particle size, apoVLDL-II was postulated to mediate smaller particle diameter of VLDLy to facilitate VLDLy penetration across the barrier of follicle layers for yolk deposition. Therefore, the study aimed to prove that apoVLDL-II really mediates physical changes of VLDLy size. A dramatic level of apo VLDL-II protein was found in the culture medium from primary chick hepatocytes overexpressing apoVLDL-II. Oleate (OA), estragon, and apoVLDL-II overexpression stimulated TG (triacylglycerol) secretion. Under the examination of scanning electron microscope (SEM), apo VLDL-II overexpression caused smaller VLDL particle size in the secretion. Oleate treatment and apo VLDL-II overexpression also increased MTP (microsomal transfer protein) expression. These results suggested that the presence apo VLDL-II mediates physic changes of VLDL particle size, and regulate intracellular lipid availability to facilitate VLDL assembly and secretion.