Synthetic promoters (SPs) have many advantages over their natural counterparts, especially with regard to transcriptional activity and tissue specificity. Here, we report a new strategy to construct SPs for efficient and muscle-specific gene expression. First, 19 nucleic acid motifs classified to 3 kinds of transcriptional regulatory elements were rationally selected. A recombinant promoter library was constructed by randomly assembling these motifs. Second, the transcriptional activities of ~1200 SPs were screened by intramuscular expression of several reporter genes in different cell lines for activity higher than that of the cytomegalovirus (CMV) promoter, with SP-301 finally identified as the strongest. A single intramuscular injection of mice with an SP-301 plasmid expressing mouse growth hormone releasing hormone accelerated mouse growth significantly over 24 days. Third, the muscle specificity of SP-301 was confirmed in transgenic mice. Finally, in comparison with the CMV promoter, SP-301 accelerated translocation and increased the level of plasmid in the nuclei of myoblast cells to a greater extent than in non-muscle cells. Altogether, the study has provided a more rational strategy to construct efficient and tissue-specific promoters, with the promoter SP-301 exhibiting promising potential for establishing an intramuscular gene expression system for therapeutic applications.

中文翻译：

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合成启动子，可有效和肌肉特异性地表达外源基因。

合成启动子（SP）与天然启动子相比具有许多优势，特别是在转录活性和组织特异性方面。在这里，我们报告了一种构建高效和肌肉特异性基因表达的SP的新策略。首先，合理选择分类为3种转录调控元件的19个核酸基序。通过随机组装这些基序来构建重组启动子文库。其次，通过肌内在不同细胞系中多个报告基因的肌肉表达来筛选〜1200 SPs的转录活性，使其活性高于巨细胞病毒（CMV）启动子的活性，最终确定SP-301最强。用表达小鼠生长激素释放激素的SP-301质粒单次肌内注射小鼠可在24天内显着加速小鼠生长。第三，在转基因小鼠中证实了SP-301的肌肉特异性。最后，与CMV启动子相比，SP-301加速了移位，并使成肌细胞细胞核中质粒的水平增加了，其程度比非肌肉细胞中更大。总之，该研究为构建有效的组织特异性启动子提供了更合理的策略，启动子SP-301在建立用于治疗应用的肌内基因表达系统方面显示出有希望的潜力。与非肌肉细胞相比，SP-301加速了移位，并在成肌细胞细胞核中增加了质粒水平。总之，该研究为构建有效的组织特异性启动子提供了更合理的策略，启动子SP-301在建立用于治疗应用的肌内基因表达系统方面显示出有希望的潜力。与非肌肉细胞相比，SP-301加速了移位，并在成肌细胞细胞核中增加了质粒水平。总之，该研究为构建有效的组织特异性启动子提供了更合理的策略，启动子SP-301在建立用于治疗应用的肌内基因表达系统方面显示出有希望的潜力。