Chicken 7SK promoter drives efficient shRNA transcription with species specificity

To extend the use of RNAi in chicken, we have developed a RNA interference (RNAi) system using a shortened chicken 7SK (ch7SK) promoter. The results stated that the cloned ch7SK promoter includes multiple Oct-1 motifs, SPH domain, PSE and TATA box, without CACCC box. All RNAi groups driven by ch7SK promoter showed significant mean fluorescence intensity (MFI) reduction. In the pch7SK-shEGFP transfected DF-EGFP cell culture, the MFI reduction ratio was smaller than the pmU6-shEGFP did. In the pmU6-shEGFP transfected Vero-EGFP cell culture, the MFI was reduced significantly than the pch7SK-shEGFP did. In summary, the essential part of ch7SK promoter was capable of efficiently expressing shRNAs with relatively different interfering degrees in avian and mammalian cells, respectively. Our results suggest that ch7SK promoter is an efficient alternative to commercially mouse U6 promoter in shRNA expression with chicken cells, and provide references for furthering functional genome analysis and disease resistant breeding in chicken.