二十碳五烯酸經由
PGC-1α與 p38 MAPK 路徑刺激粒線體生合成 Eicosapentaenoic acid (EPA) stimulates Mitochondrial Biogenesis through PGC-1α and p38 MAPK pathways
中文摘要
過氧化小體增生活化受體γ共同活化子-1α (peroxisome proliferator- activated receptor γ coactivator -1α, PGC-1α)是調節粒線體生合成的重要調節物。我們實驗 室先前已發現二十碳五烯酸(eicosapentaenoic acid, EPA)可增加 PGC-1α 與 TFAM (mitochondrial transcription factor A)基因表現與粒線體功能。本次實驗探討 EPA 是否經由p38 裂質素活化蛋白激酶(p38 mitogen-activated protein kinase, p38 MAPK)路徑調控 PGC-1α基因表現，進而影響粒線體相關基因表現。結果發現 給予25 μM 的 EPA 處理後，會顯著增加 p38 MAPK 蛋白質磷酸化，但不改變 p38 蛋白質表現，且使用共軛焦顯微鏡觀察到磷酸化之 p38 會轉位進入細胞核 中，然而隨著EPA 處理時間增加，核內之轉錄因子 CREB (cAMP response element binding protein)與 ATF2 (activating transcription factor 2)蛋白質磷酸化亦有增加傾 向。使用報導基因分析發現，給予25 μM 的 EPA 24 小時處理會增加 PGC-1α 促
進子轉錄活性。使用同步定量聚合酶反應分析發現，EPA 處理會增加粒線體 DNA
(mitochondrial DNA, mtDNA)之套數，且投予 48 小時之 EPA 會促使 mtDNA 轉譯 的蛋白質ND6 (NADH dehydrogenase 6)表現傾向增加，但不影響核轉譯之粒線體 複合體蛋白質ATP synthase 與 succinate ubiquinol oxidoreductase 蛋白質表現。而 給予EPA 不同濃度與時間處理，低於 100 μM 才不會影響 C6 神經膠瘤細胞的
細胞型態與產生細胞毒性。本次實驗支持予C6 神經膠瘤細胞 EPA 處理會刺激
PGC-1α轉錄且影響粒線體功能是透過 p38 MAPK 路徑。
英文摘要
Peroxisome proliferator- activated receptor γ coactivator -1α (PGC-1α) is a key regulator of mitochondrial biogenesis. Our previous studies have been reported that eicosapentaenoic acid (EPA, n-3 C20:5) could increase pgc-1α and TFAM gene expression and mitochondrial function. To determine whether EPA stimulated pgc-1α gene transcription and resulted in elevated mitochondrial function were through the activation of the p38 mitogen-activated protein kinase (MAPK) pathway, we investigated the role of p38 MAPK in EPA-induced transcription of pgc-1α and mitochondrial gene. We showed increased phosphorylation level of p38 MAPK in C6 glioma cells that treated with 25 μM EPA and no changed levels of total-p38 (T-p38) determined by immunobloting. Following the treatment of 25 μM EPA increased phosphorylation level of CREB and ATF2. After treatment with 25 μM EPA for 24 hr, the pgc-1α promoter transcriptional activity was increased by reporter assay. The
raised mitochondrial DNA (mtDNA) copy number was also determined in the same treated cells by real-time PCR analysis. EPA treatment could raise the expression of mtDNA encoded mitochondrial protein-ND6, but not nuclear encoded mitochondrial protein-ATP synthase and succinate ubiquinol oxidoreductase. However, there was no morphology change in cells treated with both of 25 μM and 50 μM EPA for 48 hr.
These studies supported that EPA stimulated pgc-1α transcription and further resulted to augmente mitochondrial function in C6 glioma cell were mediated through the activation of the p38 MAPK pathway.
