CMV与SP双启动子增强外源基因在小鼠骨骼肌中的表达效率

构建分别含有CMV、肌肉特异启动子SP及双启动子CMV-SP的真核报告基因EGFP表达载体（pCMV-EGFP、pSP-EGFP及pCMV-SP-EGFP）和生长激素释放因子（GRF）表达载体（pCMV-GRF、pSP-GRF和pCMV-SP-GRF）.将3种EGFP表达质粒分别注射至小鼠骨骼肌.注射后1周、2周、3周以及4周时,分别提取肌肉组织RNA，应用半定量RT-PCR检测报告基因（EGFP）的表达量，发现pCMV-SP-EGFP组EGFP表达量显著高于pCMV-EGFP组和pSP-EGFP组（P<0.01）；经荧光检测得到了较强的荧光信号.将3种GRF表达质粒分别注射至小鼠骨骼肌，在注射后每10 d记录小鼠累积增重，采血并用RIA法测定血清胰岛素样生长因子Ⅰ（IGF-Ⅰ）浓度，结果pCMVSP-GRF组累积增重、IGF-I浓度分别高于生理盐水组、pCMV-GRF组和pSP-GRF组（P<0.05）.结果表明：CMV与SP两种启动子组合，在小鼠骨骼肌内使外源基因表达效率提高.本研究为提高外源基因在肌肉组织的表达提供了新的途径.

Two Promoters CMV and SP Enhance the Expression Efficacy of an Exogenous Gene in Skeletal Muscle of Mice

Six vectors were constructed,which were carrying EGFP or GRF (pCMV-EGFP, pSP-EGFP, pCMV-SP-EGFP, pCMV-GRF, pSP-GRF and pCMV-SP-GRF) driven by CMV promoter, SP promoter and CMV-SP promoters, respectively. They were injected into skeletal muscle of mice to observe their expression efficacy. The differences of EGFP expressions of the vectors were evaluated by semi-quantitative polymerase chain reaction (PCR) at 1, 2, 3 and 4 weeks postinjection. The results showed that the expression of the EGFP with two promoters was significantly higher than the groups of pCMV-EGFP and pSP-EGFP (P< 0.01) . The accumulative weight gain of mice and concentrations of serum IGF-I were measured in every 10 days. The results showed that injection of pCMV-SP-GRF lead to accumulative weight gain and serum IGF-I levels were significantly higher than the groups of pCMV-GRF and pSP-GRF (P< 0.05). The results indicated that the two promoters combined gained more robust expression of exogenous gene. This result would provide a beneficial exploring to improve the efficiency of gene expression in skeletal muscle.