高親和性磷酸二酯酶對衰老細胞粒線體調控之探討

The Role of High Affinity Phosphodiesterase PDE2 in Mitochondria of Senescent Yeast Cells

尤鈺慈(Yu, Yu Tzu)

指導教授 ： 張壯榮

國立清華大學/生命科學院/生物科技研究所/碩士(2015年)

摘要

粒線體是一種不斷進行融合與分裂的動態胞器，粒線體動態平衡對於維持粒線體的功能非常重要。老化是一種造成生理與粒線體功能損害的退化性過程，在老化的酵母菌細胞中粒線體呈現破碎的型態。白藜蘆醇是一種抗老的天然多酚，我們發現白藜蘆醇除了降低衰老酵母菌細胞中活性氧化物的含量，也減少破碎的粒線體，但對於白藜蘆醇如何調控粒線體的機制並不清楚。有研究指出，白藜蘆醇可以透過抑制磷酸二酯酶的活性來改善細胞中老化的現象，因此我們針對磷酸二酯酶對於衰老酵母菌細胞中粒線體作用加以探討。本論文的實驗結果指出，白藜蘆醇無法在缺乏磷酸二酯酶的衰老酵母菌細胞中改變粒線體型態，且其調控粒線體融合分裂基因也有不同的表現; 另外，白藜蘆醇亦無法在缺乏磷酸二酯酶的衰老酵母菌細胞中減低活性氧化物的含量。我們進一步發現磷酸二酯酶的下游因子:環腺苷酸及蛋白激酶A也參與白藜蘆醇改變粒線體型態及降低活性氧化物的機制。我們的研究結果指出，白藜蘆醇在衰老酵母菌中調控粒線體型態及降低活性氧化物的含量需要透過磷酸二酯酶來達成。

關鍵字

粒線體動態平衡 ； 衰老 ； 白藜蘆醇 ； 磷酸二酯酶

並列摘要

Mitochondria are dynamic organelles that continuously undergo fusion and fission. Mitochondrial dynamics is important for maintaining mitochondrial integrity and cellular function. Aging is a degenerative process that exhibit physiological and mitochondrial dysfunction. Previous studies of our lab revealed mitochondrial fragmentation was present in senescent yeast cells. Resveratrol, a polyphenol mitigated mitochondrial fragmentation and superoxide level. In addition, resveratrol elevated membrane potential in the senescent yeast cells. However, the mechanism of how resveratrol-mediated mitochondria in senescent yeast cells remains unclear. We aim to elucidate the potential mechanisms. Previous studies indicated resveratrol can ameliorate aging-related metabolic phenotypes via inhibiting phosphodiesterase activity. In this thesis, I applied biotin-streptavidin system to isolate replicative senescent yeast cells to clarify the effect of phosphodiesterase, Pde2 on mitochondria. My results demonstrated that deletion of PDE2 reverted the effects of resveratrol on mitochondria dynamics and showed different transcription level of fission/ fusion genes. In the mitochondrial activity assay, resveratrol did not mitigate the superoxide level in Δpde2 senescent cells. Those results indicated that Pde2 is required for resveratrol-mediated mitochondrial dynamics and superoxide scavenging. These evidences provide hints to elucidate resveratrol signaling pathway in the regulation of mitochondrial dynamics in cellular senescence.

並列關鍵字

mitochondrial dynamics ； senescent ； resveratrol ； phosphodiesterase

參考文獻

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