鸡卵清蛋白基因第一内含子和3′-调控区对外源基因表达的调控作用

The Regulatory Effect of the First Intron and 3′-Regulatory Region of Ovalbumin Gene on Transgene Expression

摘要:

探明鸡卵清蛋白基因(ov)第一内含子和3′-调控区对目的基因表达水平的影响, 为鸡输卵管表达载体的构建提供科学依据。用牛生长激素基因(BGH)poly A序列替换鸡输卵管表达载体中ov 3′-调控区, 用限制酶消化法逐步删减第一内含子序列, 获得5个表达人组织激肽释放(hK1)cDNA的鸡输卵管表达载体, 分别命名为pOV2K、pOV3K、pOV4K、pOV5K和pOV6K。经翅静脉给产蛋鸡注射聚乙烯亚胺包裹的相同拷贝数重组载体, 通过蛋清中酶活性定量检测评价不同载体的表达水平。结果表明: 受控于3.0kb ov 5′-和3′-调控区的pOV2K表达的重组酶活性明显高于用BGH poly A 替换3′-调控区的pOV3K; 无内含子的pOV6K表达水平显著低于含不同长度第一内含子的pOV3K、pOV4K和pOV5K, 重组酶表达水平随第一内含子的缩短呈逐渐下降趋势。该试验结果表明ov第一内含子和3′-调控区对目的基因在鸡输卵管细胞中的表达具有正调节作用, 应当包括在鸡输卵管表达载体中。

Abstract:

We studied the influence of the first intron and 3′-regulatory region of ovalbumin gene (ov) on oviduct-specific transgene expression. The 3′-regulatory region in the oviduct-specific expression vector containing human tissue kallikrein (hK1) cDNA was replaced with bovine growth hormone (BGH) poly A, and the first intron was deleted by restriction enzyme digestion, resulting in five new vectors pOV2K, pOV3K, pOV4K, pOV5K and pOV6K. After mixing with polyethylenimine, we injected same copies of the five vectors via wing vein route into laying hens and compared their expression levels by quantitative assay for enzymatic activities in the egg whites. Among the five vectors tested, the pOV2K containing both the 5′- and 3′-regulatory regions expressed highest level of rhK1 activity, followed by pOV3K with the 3′-regulatory region replaced with BGH poly A, and then by the first intron-shortened vectors pOV4K, pOV5K and pOV6K. These data suggest that both the first intron and 3′-regulatory region of ov gene have enhancing effect on transgene expression in oviduct cells, which should be included in oviduct-specific expression vectors.