葉酸補充對氧化壓力影響中國大頰鼠卵巢細胞株粒線體DNA生合成轉錄因子之調控

Effect of Folate Supplementation on Transcriptional Regulation of Factors Involving Mitochondrial DNA Biogenenesis in Chinese Hamster Ovary Cells under Oxidative Stress Challenge

葉宜玲(Yi-Ling Ye) ； 許瑞芬(Rwei-Fen S. Huang)

《臺灣營養學會雜誌》 32卷3期 (2007/09) Pp. 94-101

https://doi.org/10.6691/NSJ.200709_32(3).0003

摘要

氧化壓力的增加會誘發粒線體增生及功能性損傷。葉酸為－抗氧化營養分子，但葉酸如何調節粒線體增生的機制尚未被了解。本研究選用中國大頰鼠卵巢細胞野生株CHOK1，粒線體serine hydroxylmethyltransferase酵素(mSHMT)缺陷突變株GLYA及粒線體葉酸轉運蛋白缺陷突變株GLYB為研究模式，探討在氧化壓力下，補充葉酸如何調節粒線體生合成機制。投與外來氧化壓力t-butylhyhroperoxide(t-BH)處理48小時後，以即時定量PCR測定調節粒線體生合之轉錄因子之表現。結果顯示，t-BH處理48小時後，粒線體葉酸缺乏GLYB細胞中粒線體生合成相關轉錄因子mitochondrial transcription factor(mtTFA)之mRNA與mtDNA polymerase γ(mt pol γ)表現量顯著增加，mt single stranded DNA binding protein(mtSSB)表現量顯著降低。CHOK1與GLYA細胞中nuclear respiratory factor(NRF)1、2、mtTFA與mt pol γ則無顯著改變。葉酸補充可顯著降低GLYB因t-BH誘發之增加的mtTFA表現量，但對其他與粒線體增生相關因子表現則無影響。縱合上述，補充葉酸可部份調節因粒線體葉酸缺陷而影響之粒線體增生相關因子之表現。

關鍵字

葉酸補充 ； 粒線體生合成 ； 中國大頰鼠卵巢細胞 ； 氧化壓力

並列摘要

Increased oxidative stress results in mitochondrial (mt) DNA damage, mt dysfunction, and enhanced mt biogenesis. The aims of the study were to investigate the effect of folate supplementation on the transcriptional regulation of factors involved in mtDNA biogenenesis in Chinese hamster ovary (CHO) cells upon oxidative stress challenge. CHO cell lines including wild type CHOK1, GLYA mutant with defective mt serine hydroxyl-methyltransferase and GLYB mutant with defective mt folate transport protein were used as experimental models. CHO cells were treated with t-butylhyhroperoxide (t-BH) for 48 h. Gene expressions of transcriptional factors for mt biogenesis were assayed by real-time polymerase chain reaction. Oxidative stress induced increased the expressions of mt transcription factor A (mtTFA) and mtDNA polymerase γ (mt pol γ), and decreased the expression of mt single-stranded DNA binding protein (mtSSB) in GLYB. Pre-incubation of GLYB with 10-100 μM folate significantly reduced mtTFA expression. In CHDK1 and GLYA cells, t-BH treatment did not alter the gene expressions of nuclear respiratory factors 1 or 2, mtTFA, or mtDNA mt pol γ. In summary, folate supplementation partially offset mt folate deficits as the result of defective mt folate metabolism to normalize t-BH-induced expressions of mtTFA for mtDNA biogenesis.

並列關鍵字

folate supplementation ； mitochondrial biogenesis ； CHO cell ； oxidative stress