PPARGC1A基因多形性、粒線體DNA含量與缺血性中風之相關性研究

Association Study on Genetic Polymorphism of Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α, Mitochondrial DNA Content and Ischemic Stroke

邱尚彥(Shang-Yen Chiu)

指導教授 ： 謝芳宜

臺北醫學大學/公共衛生暨營養學院/公共衛生學系暨研究所/碩士(2014年)

摘要

腦血管疾病是全世界人口的主要死因之一，其中缺血性腦中風約占腦血管疾病的70%。氧化壓力所造成的動脈粥狀硬化可能造成缺血性中風的發生，粒線體被認為是內生性反應性氧化物種 (ROS) 的主要來源，粒線體的功能異常可能造成細胞的氧化壓力，並且導致心血管細胞的病變。PPARGC1A基因會轉譯出PGC-1α，PGC-1α參與了許多轉錄調節路徑，包括了調控粒線體DNA拷貝數與功能的維持，而粒線體DNA含量與維持粒線體的功能可能具有相關。然而，PPARGC1A基因與粒線體DNA含量對於缺血性腦中風的致病機制仍尚未釐清；因此，我們執行了一項病例對照研究以評估PPARGC1A基因多形性與粒線體DNA含量對於缺血性中風的危險性。
本研究根據性別與年齡配對後，總共納入350名缺血性中風病例與350名健康對照。研究對象會經由標準化訓練之訪員進行面訪，並透過結構式問卷收集相關資料，包括了基本人口學特徵、生活習慣、疾病史、藥物使用情形、身體測量以及取得血液樣本測量實驗室生化數值。以PCR-RFLP或PCR-CTPP來判定PPARGC1A基因單核苷酸多形性，並以定量即時聚合酶鏈鎖反應測定周邊血液粒線體DNA含量。羅吉斯迴歸被用來求取PPARGC1A基因多形性或粒線體DNA含量對於缺血性中風的危險對比值以及95%信賴區間；使用協同指數評估已知危險因子與PPARGC1A基因型多形性或粒線體DNA含量對於缺血性中風的交互作用。
我們的研究發現，帶有PPARGC1A rs2970865 C對偶基因者相較於TT基因型者有顯著較高的缺血性中風危險性；而相較於帶有rs8192678 G對偶基因者，AA基因型者有顯著較低的缺血性中風危險性。缺血性中風的病例相較於健康對照，有顯著較低的周邊血液粒線體DNA含量，而粒線體DNA含量的減少，會顯著地增加缺血性中風的危險性；粒線體DNA含量與代謝症候群、高血壓、糖尿病以及吸菸，對於缺血性中風的危險性具有顯著的交互作用。此外，在缺血性中風的病例中，我們觀察到rs2970865與粒線體DNA含量具有顯著相關。
PPARGC1A基因多形性及粒線體DNA含量對於缺血性中風的致病機制可能扮演著重要的角色，將來應該透過功能性的研究以驗證PGC-1α的表現異常及粒線體DNA含量的變化對於缺血性中風發生的影響。

關鍵字

缺血性中風 ； 氧化壓力 ； PPARGC1A基因多形性 ； 粒線體DNA含量

並列摘要

Cerebrovascular diseases are the leading causes of death around the world, and about 70% of cerebrovascular diseases are ischemic stroke. Oxidative stress induced the formation of atherosclerosis which is one of the important causes of ischemic stroke. Mitochondria are the major source of endogenous reactive oxygen species (ROS). Mitochondrial dysfunction may increase cellular oxidative stress and induce cardiovascular lesions. The protein PGC-1α, encoded by the PPARGC1A gene, regulates lots of transcription pathway, some of which are key factors in regulating mitochondrial DNA (mtDNA) copy numbers and maintenance of mitochondrial function. However, the role of PPARGC1A gene and mtDNA content in pathogenesis of ischemic stroke is unclear. Therefore, we conducted a case-control study to evaluate genetic polymorphism of PPARGC1A and mtDNA content on the risk of ischemic stroke.
Three hundred and fifty ischemic stroke patients and 350 healthy controls were recruited in this study. Controls were matched with cases by gender and age (?b5 years). All study subjects were interviewed by well-trained interviewers using a structural questionnaire including demographics data, disease histories, and lifestyle. Biochemical data were measured from fasting blood. The genotypes of PPARGC1A gene were identified by PCR-RFLP or PCR-CTPP. The mtDNA content of white blood cells from peripheral blood were measured by quantitative real time-PCR. Odds ratio (OR) and 95% confidence intervals (C.I.) were calculated by logistic regression models. Synergy index scores were used to evaluate interaction between the PPARGC1A gene or mtDNA content and the traditional risk factors of cardiovascular disease on the risk of ischemic stroke.
Our results showed that subjects with PPARGC1A rs2970865C allele significantly increased the risk of ischemic stroke, as compared to the subjects with CC genotype. Subjects with rs8192678 AA genotype significantly increased the risk of ischemic stroke, as compared to the subjects with G allele. Compared to healthy controls, ischemic stroke patients had dramatically lower levels of mtDNA content. A significant association between lower mtDNA content and increased ischemic stroke risk was found in this study. The significant interactions were observed between the mtDNA content and metabolic syndrome, hypertension, diabetes, or smoke on the risk of ischemic stroke.
In conclusion, PPARGC1A genetic polymorphism and mtDNA content might play crucial roles in the pathogenesis of ischemic stroke. Further functional studies are required to prove the role of PGC-1α and mtDNA content on the development of ischemic stroke.

並列關鍵字

ischemic stroke ； oxidative stress ； PPARGC1A genetic polymorphism ； mitochondrial DNA content

參考文獻

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