摘要：In genetics, the promoter is one of the most important regulatory elements controlling the spatiotemporal expression of a target gene. However, most studies have focused on core or proximal promoter regions, and information on regions that are more distant from the 5′-flanking region of the proximal promoter is often lacking. Here, approximately 4-kb of the sericin 1 ( Ser 1) promoter was predicted to contain many potential transcriptional factor binding sites (TFBSs). Transgenic experiments have revealed that more TFBSs included in the promoter improved gene transcription. However, multi-copy proximal Ser 1 promoter combinations did not improve gene expression at the transcriptional level. Instead, increasing the promoter copy number repressed transcription. Furthermore, a correlation analysis between two contiguous genes, firefly luciferase ( FLuc ) and EGFP , was conducted at the transcriptional level; a significant correlation was obtained regardless of the insertion site. The ELISA results also revealed a significant correlation between the transcriptional and translational EGFP levels. Therefore, the exogenous gene expression level can be predicted by simply detecting an adjacent EGFP . In conclusion, our results provide important insights for further investigations into the molecular mechanisms underlying promoter function. Additionally, a new approach was developed to quickly screen transgenic strains that highly express exogenous genes.
