title: A simple and robust vector-based shRNA expression system used for RNA interference.
abstract: BACKGROUND
  RNA interference (RNAi) mediated by small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) has become a powerful genetic tool for conducting functional studies. Previously, vector-based shRNA-expression strategies capable of inducing RNAi in viable cells have been developed, however, these vector systems have some disadvantages, either because they were error-prone or cost prohibitive.
  
  
  RESULTS
  In this report we described the development of a simple, robust shRNA expression system utilizing 1 long oligonucleotide or 2 short oligonucleotides for half the cost of conventional shRNA construction methods and with a >95% cloning success rate. The shRNA loop sequence and stem structure were also compared and carefully selected for better RNAi efficiency. Furthermore, an easier strategy was developed based on isocaudomers which permit rapid combination of the most efficient promoter-shRNA cassettes. Finally, using this method, the conservative target sites for hepatitis B virus (HBV) knockdown were systemically screened and HBV antigen expression shown to be successfully suppressed in the presence of connected multiple shRNAs both in vitro and in vivo.
  
  
  CONCLUSIONS
  This novel design describes an inexpensive and effective way to clone and express single or multiple shRNAs from the same vector with the capacity for potent and effective silencing of target genes.
authors: Department of Biotechnology, Beijing Institute of Radiation Medicine, Beijing, People's Republic of China.
authors: Xue-jun
authors: XJ
authors: Wang
authors: Ying
authors: Y
authors: Li
authors: Hai
authors: H
authors: Huang
authors: Xiu-juan
authors: XJ
authors: Zhang
authors: Pei-wen
authors: PW
authors: Xie
authors: Wei
authors: W
authors: Hu
authors: Dan-dan
authors: DD
authors: Li
authors: Sheng-qi
authors: SQ
authors: Wang
mesh_terms: D000818:Animals; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000821:virology; D015967:Gene Expression Regulation, Viral; D020868:Gene Silencing; D005818:Genetic Engineering; D005822:Genetic Vectors; D006514:Hepatitis B Surface Antigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006513:Hepatitis B e Antigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000821:virology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D034741:RNA, Small Interfering