抑制異檸檬酸去氫酶A-1表現降低線蟲壽命及抗氧化壓力

Knockdown of Isocitrate Dehydrogenase A-1 Reduces Lifespan and Oxidative Stress Tolerance in Caenorhabditis elegans

張舜雅

指導教授 ： 汪宏達

國立清華大學/生命科學院/生物科技研究所/碩士(2013年)

摘要

檸檬酸循環在許多研究中已經被證實跟壽命的延長有相當大的關係，並且為代謝途徑當中相當重要的的一環。此篇研究中我使用線蟲為模式生物來探討異檸檬酸去氫酶得表現量對於線蟲的壽命的影響，我發現如在線蟲中利用RNAi 的方式來降低線蟲異檸檬酸去氫酶 (idha-1 )的表現量，會使線蟲的壽命減少。此外，降低線蟲中idha-1的表現量也會使線蟲對氧化壓力的抗性降低，且NADPH及NAD的含量在idha-1 RNAi作用下也會減少。也進一步利用即時偵測線蟲耗氧量發現降低idha-1會減少線蟲的耗氧量，表示idha-1的表現量會影響線蟲有氧呼吸及產生能量的能力。另外，為了想知道idha-1在線蟲中是否和其他代謝調控有關係，也利用反轉錄聚合酶鏈鎖反應發現某些細胞自噬反應相關基因 (bec-1、unc-51) 的表現量下降，以及脂肪分解酶 (lipl-4) 、清除自由基蛋白基因 (sod-3)等基因調控量都有下降的趨勢。我也利用STRING 蛋白交互作用資料庫發現IDHA-1和IDHB-1及IDHG-2有結合關係，且減少此兩種基因的改變也會造成線蟲壽命減少。本研究指出，idha-1在維持基本壽命及氧化壓力耐受度上是必要的。

關鍵字

異檸檬酸去氫酶 ； 三羧酸循環 ； 氧化壓力

並列摘要

Tricarboxylic acid cycle (TCA cycle) is an essential metabolism pathway and plays an important role in extending lifespan. In this research, I studied the effect of isocitrate dehydrogenase A-1 (idha-1) expression upon RNAi knockdown on the lifespan in C. elegans. Here I found that RNAi knockdown of idha-1 shortens the lifespan and also decreases the oxidative stress tolerance in C. elegans. Both the NADPH+ and NAD+ concentrations in the idha-1 RNAi treated worms were down-regulated. Furthermore, the decreased oxygen consumption indicates that lower respiration rate and weaker energy production capability occur in the idha-1 RNAi knockdown worms. In addition, several aging related genes expression were altered upon idha-1 knockdown, like autophagy related genes: unc-51 and bec-1, lipase gene: lipl-4, ROS scavenger gene: sod-3, were down regulated in the idha-1 knockdown worms. I used STRING functional protein association networks found IDHA-1 can bind with IDHB-1 and IDHG-2. By RT-PCR, I found that knockdown of idha-1 also decreased the expression levels of idhb-1 and idhg-2, which both also reduce lifespan in C. elegans. Knockdown of idha-1, idhb-1, or idhg-2 reduces the extended lifespan of eat-2 mutant. Together, my thesis research indicated that idha-1 is required to maintain normal lifespan and uphold oxidative stress tolerance.

並列關鍵字

TCA cycle ； Isocitrate Dehydrogenase ； IDHA-1 ； oxidative stress

參考文獻

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