High doses of siRNAs induce eri-1 and adar-1 gene expression and reduce the efficiency of RNA interference in the mouse

Biochem J. 2005 Sep 15;390(Pt 3):675-9. doi: 10.1042/BJ20050647.


RNAi (RNA interference) is a gene-silencing mechanism that is conserved in evolution from worm to human and has been a powerful tool for gene functional research. It has been clear that the RNAi effect triggered by endogenous or exogenous siRNAs (small interfering RNAs) is transient and dose-dependent. However, there is little information on the regulation of RNAi. Recently, some proteins that regulate the RNA-silencing machinery have been identified. We have observed in previous work that the expression of target genes rebounds after being suppressed for a period of time by siRNAs. In the present study, we used secretory hepatitis B virus surface antigen gene as a reporter and compared its expression level in cell culture and mice challenged by different doses of siRNAs. A quicker and higher rebound of gene expression was observed in mice tail-vein-injected with higher doses of siRNA, and the rebound was associated with an increase in the mRNA level of meri-1 (mouse enhanced RNAi) and adar-1 (adenosine deaminase acting on RNA) genes encoding an exonuclease and RNA-specific adenosine deaminase respectively. Down-regulation of meri-1 by RNAi enhanced the sensitivity and efficiency of siRNA in inhibiting the expression of hepatitis B virus surface antigen. These results indicate that RNAi machinery may be under negative regulation, through the induction of a series of genes coding for destabilizing enzymes, by siRNAs introduced into the cell, and also suggest that a suitable amount of siRNA should be used for research or therapeutic applications.

MeSH terms

  • Adenosine Deaminase / genetics*
  • Animals
  • CHO Cells
  • Cricetinae
  • Exonucleases / genetics*
  • Exoribonucleases
  • Hepatitis B Surface Antigens / genetics
  • Hepatitis B Surface Antigens / metabolism
  • Male
  • Mice
  • RNA Interference / physiology*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism*
  • RNA-Binding Proteins


  • Hepatitis B Surface Antigens
  • RNA, Messenger
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Eri1 protein, mouse
  • Exonucleases
  • Exoribonucleases
  • ADARB1 protein, human
  • Adenosine Deaminase