台灣族群帕金森氏症FBXO7 基因變異的分子遺傳及功能研究

Abstract

帕金森氏症主要為中腦黑質緻密區的多巴胺神經細胞缺失所引起的神經退化性疾病。FBXO7基因位於染色體22號q12-q13上，與家族性早發性帕金森氏症和錐狀體病症有相關。FBXO7蛋白由522個胺基酸組成，N端帶有ubiquitin-like fold、C端帶有F-box domain，為ubiquitin E3 ligase complex內的重要因子。本研究探討FBXO7基因變異與台灣族群帕金森氏症的相關性。首先針對家族性及早發性84位帕金森氏症病人進行FBXO7 cDNA定序分析，結果共發現二個兩個多型性點Y52C (c.155A>G)、I115M (c.345A>G)。進一步對所蒐集的帕金森氏症病人(516位)與性別、年齡相當的正常人(516位)進行Y52C、I115M的病例-對照組分析，結果顯示Y52C多型性G等位基因頻率在病人族群中明顯較正常人族群低，且和低帕金森氏症感受性相關(0.4% vs. 1.2%, P = 0.046)。進一步結合中國大陸數據(Luo et al., 2010)，651位病人與716位正常人的病例-對照組分析結果亦顯示低帕金森氏症感受性(0.5% vs. 1.4%, P = 0.012)及低罹病機率(odds ratio: 0.33, 95% confidence interval: 0.12-0.77, P = 0.017)。目前已建構EGFP標記及V5-His和pcDNA5/FRT/TO的FBXO7 cDNA質體，表現於SH-SY5Y及HEK-293T細胞，進行次細胞分層、西方轉漬、螢光顯微鏡分析、蛋白穩定性、蛋白質體功能分析和神經纖維分析。本實驗希望可提供疾病診斷及遺傳諮詢的文獻。 關鍵字: 帕金森氏症、神經退化性疾病、FBXO7 基因、多型性點Y52CParkinson's disease (PD) is a progressive neurodegenerative disorder caused by with loss of dopamine neurons in the SNc. The chromosome 22q12-q13 FBXO7 mutations have been identified in several families with early-onset parkinsonism and pyramidal tract signs. FBXO7 gene codes for a protein of 522 amino acids, with an ubiquitin-like fold in its N-terminal and an F-box in its C-terminal half. FBXO7 is a key component of an ubiquitin E3 ligase complex. This study investigates the FBXO7 variability in Taiwanese PD. By direct cDNA sequencing of 84 patients with familiar or early-onset PD, two amino acid changed variants Y52C (c.155A>G) and I115M (c.345A>G) were identified. To examine whether Y52C and I115M affect the risk of PD, PCR-RFLP test was developed to assess their frequency in a larger cohort of PD (n = 516) and age- and gender-matched controls (n = 516). We found The Y52C G allele frequency was notably lower in PD patients than the controls (0.4% vs. 1.2%, P = 0.046). After combining data from China (Luo et al., 2010), the Y52C G allele frequency is significantly different between PD (n = 651) and controls (n = 716) (0.5% vs. 1.4%, P = 0.012) and a significant decrease in risk of developing PD can be demonstrated (odds ratio: 0.33, 95% confidence interval: 0.12-0.77, P = 0.017). Cloning and expressing of cDNAs with Y52C in dopaminergic neuroblastoma SH-SY5Y cells and HEH-293T cell are currently ongoing to examine if Y52C affect FBXO7 localization, protein stability, proteasome activity and neurite outgrowth. The study may provide a reference for clinical diagnosis and genetic counseling. key words:Parkinson’s disease (PD)、neurodegenerative disorder、FBXO7 gene、Y52C polymorphism、Dopamine