營養素調控粒線體生合成及細胞能量代謝之研究

粒線體為細胞中主要產能的胞器，參與了體內多種生理生化代謝路徑，擔任維持代謝平衡不可或缺的角色。飲食中的營養素經糖解及脂肪酸氧化等生化路徑，最終需進入粒線體Tricarboxylic acid cycle (TCA) cycle代謝及粒線體內膜上呼吸電子傳遞鏈來產生ATP，以供細胞所需。骨骼肌與腦為體內代謝旺盛的組織，需要消耗大量的能量、粒線體的功能是否健全及粒線體生合成之情形，皆會影響骨骼肌及腦部的運作。肌肉細胞作功需要消耗大量能量，介由葡萄糖及脂肪酸代謝後，最後由呼吸電子傳遞鏈氧化磷酸化產生ATP供細胞所需。而棕色脂肪細胞產熱時，需藉粒線體內膜上uncoupling protein去偶合蛋白作用，以另一種形式消耗能量以熱的形式釋放，而產生熱能。因此，在粒線體功能正常前提之下，增加粒線體生合成對細胞代謝途徑皆有幫助。例如：增加粒線體生合成可增加運動時肌肉耐受力、增加抵抗低溫環境的能力、維持體內代謝平衡，減少代謝上的疾病。然而，目前少有研究指出某營養素可直接藉由基因層次上的調控增加粒線體生合成。近來研究較常被證實的為運動或是熱量限制進而使得粒線體生合成增加。因此，本研究建立可透過轉錄因子調控粒線體生合成之穩定轉染細胞，將可能增加粒線體生合成之營養素作更進一步的研究。調控粒線體生合成之路徑繁多且複雜，先前多項研究指出，PGC-1α (Peroxisome proliferator- activated receptor γ coactivator-1α)在粒線體生合成及調控粒線體功能上扮演重要調節的角色，而其下游基因NRF-1 (nuclear respiratory factor 1)與mtTFA (mitochondrial transcription factor A)也多被證實與粒線體DNA轉錄及複製所必需。因此本次實驗設計具有PGC-1α promoter的luciferase報導基因表現質體，並以穩定轉染K562細胞的方式，介入Eicosa pentaenoic acid (EPA)及白藜蘆醇，結果顯示，EPA及白藜蘆醇在介入在12小時不會促進粒線體生合成相關基因之表現量與粒線體質量，經24小時後可增加部分基因之表現量即具粒線體生合成之趨勢，但使否透過事先預期之PGC-1α promoter轉錄因子作調控仍需更多實驗證實。

關鍵字

粒線體生合成；PGC-1α promoter；魚油；白藜蘆醇

並列摘要

Mitochondria provide the principal energy source for the cell and is important in maintaining an equilibrium between energy intake, storage, and expense. The functions of mitochondria and mitochondrial biogenesis affect skeletal muscle cell and brain. Mitochondria also play an essential role in the functioning of brown adipose tissue toward heat production. Thus, we hypothesized that under the premise of normal mitochondrial function, increasing mitochondrial biogenesis may be beneficial for metabolic pathways of the cell. Mitochondrial biogenesis regulation is complicated. Previous studies show that peroxisome proliferator-activated receptor coactivator 1α (PGC-1α) is the primary regulator of mitochondrial biogenesis and function, thus becoming a crucial metabolic node. We hypothesized that PGC-1α would affect the downstream transcription factor, nuclear transcription factor 1 (NRF-1), and promoter mitochondrial transcription factor A (Tfam) which is necessary for mitochondrial DNA transcription. Therefore, the aim of this study was to determine the effect of resveratrol and EPA on peroxisome proliferator-activated receptor coactivator 1α (PGC-1α) promoter, mitochondria biogenesis markers like peroxisome proliferator-activated receptor coactivator 1α (PGC-1α), nuclear transcription factor 1 (NRF-1) and mitochondrial transcription factor A (Tfam) of the k562 stable clone cells. Thus we constructed the luciferase reporter plasmid containing PGC-1α promoter. After incorporating the plasmid into K562 cell, the stable clone was treated with ecosapentaenoic acid (EPA) (10, 20, 30, 50 μM) and resveratrol (RSV) (0.1, 0.5, 1, 10 μM), and the cell were incubated for 12, 24 hours. The activity of reporter gene was not turned on by EPA and RSV. And the marker of mitochondrial biogenesis, fluorescene intensity was not increased by treated with EPA and RSV. The results showed that EPA and RSV could not promote mRNA associated with mitochondrial biogenesis expression within 12 hours. However we can suppose that EPA and resveratrol may enhance PGC-1α mRNA expression and others mRNA about mitochondrial biogenesis expression after treatment with EPA or resveratrol for 24 hours. In conclusion, EPA or resveratrol showed potential of increasing mitochondrial biogenesis in K562 stable clone after 24 hours of treatment.

並列關鍵字

mitochondrial biogenesis ； PGC-1α promoter ； ecosapentaenoic acid ； resveratrol ； NRF- ； Tfam

參考文獻

1. Balaban RS: Regulation of oxidative phosphorylation in the mammalian cell. Am J Physiol 1990, 258:C377-389.

2. Scarpulla RC: Transcriptional paradigms in mammalian mitochondrial biogenesis and function. Physiol Rev 2008, 88:611-638.

3. Hock MB, Kralli A: Transcriptional Control of Mitochondrial Biogenesis and Function. Annual Review of Physiology 2009, 71:177-203.

4. Kelly DP, Scarpulla RC: Transcriptional regulatory circuits controlling mitochondrial biogenesis and function. Genes Dev 2004, 18:357-368.

5. Clayton DA: Vertebrate mitochondrial DNA-a circle of surprises. Experimental Cell Research 2000, 255:4-9.

國際替代計量

營養素調控粒線體生合成及細胞能量代謝之研究

全文下載

主題瀏覽