IPO8基因启动子区rs35100176位点变异对基因表达的影响

 目的：研究人importin 8（IPO8）基因启动子区rs35100176多态性位点CCT插入/缺失对基因表达的影响。方法：PCR扩增IPO8基因启动子区包含rs35100176多态位点的342 bp序列，通过测序获得了49例DNA样本的基因多态性分布。以CCT/CCT插入纯合子或-/-缺失纯合子DNA样本为模板，扩增含有不同插入/缺失序列的IPO8基因启动子片段，插入萤光素酶报告质粒pGL3-Basic，构建pGL3-3N Insertion 和pGL3-3N Deletion重组表达载体。重组质粒经Fugene 6.0转染入细胞，采用双萤光素酶报告系统，检测携带不同多态性序列的重组质粒中报告基因的表达活性；real-time PCR检测各不同基因型细胞中IPO8 mRNA表达。结果：通过测序发现rs35100176多态位点存在CCT/CCT、CCT/-和-/- 3种表型，其基因分布频率分别为1837%、5510%和2653%。成功构建pGL3-3N Insertion和pGL3-3N Deletion重组表达载体。双萤光素酶报告基因活性检测结果显示，pGL3-3N Insertion启动下游报告基因表达的相对活性与pGL3-3N Deletion相比显著减弱，两者存在显著差异（P<005）；real-time PCR结果显示，CCT纯合插入的HEK293细胞中IPO8 mRNA的表达显著低于CCT纯合缺失的Saos-2细胞。结论：IPO8基因启动子区rs35100176位点的CCT碱基插入变异能显著抑制启动子活性，从而影响IPO8基因的转录。

Effects of rs35100176 polymorphism in IPO8 promoter on gene expression

AIM: To investigate the effect of rs35100176 CCT insertion/deletion polymorphism in the promoter region of importin 8 (IPO8) gene on its mRNA expression. METHODS: A 342-bp fragment of IPO8 gene promoter containing the rs35100176 polymorphism was amplified from 49 DNA samples and sequenced. The IPO8 promoter fragments containing CCT 3-nucleotide insertion or deletion were amplified using the corresponding homozygote DNA samples. The PCR products were sequenced and inserted into the luciferase reporter vector pGL3-Basic. Recombinant vectors were transfected into the cells by Fugene 6.0 and the expression of the reporter gene was detected by a dual-luciferase reporter assay system. The mRNA expression level of IPO8 was detected by real-time PCR in 3-nucleotide insertion or deletion homozygote cells. RESULTS：The sequencing results showed that there were 3 kinds of genotypes in the rs35100176 polymorphism, CCT/CCT,CCT/- and -/-, and the gene frequencies were 1837%, 5510% and 2653%, respectively. The recombinant expression vectors pGL3-3N Insertion and pGL3-3N Deletion were successfully constructed. The luciferase assay showed that pGL3-3N Insertion produced significantly lower luciferase activity than that by pGL3-3N Deletion. Real-time PCR showed that HEK293 cells with 3-nucleotide insertion homozygote expressed relative lower IPO8 mRNA than Saos-2 cells with 3-nucleotide deletion homozygote. CONCLUSION：The CCT 3-nucleotide insertion variant decreases the promoter activity of IPO8, thus affecting the gene expression.