High doses of siRNAs induce eri-1 and adar-1 gene expression and reduce the efficiency of RNA interference in the mouse.
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.
Hong
Jie
J
Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433, China.
Qian
Zhikang
Z
Shen
Shuiyuan
S
Min
Taishan
T
Tan
Chang
C
Xu
JianFeng
J
Zhao
Yingchun
Y
Huang
Weida
W
D000243:Adenosine Deaminase / Q000235:genetics*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D005092:Exonucleases / Q000235:genetics*; D005095:Exoribonucleases; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D034622:RNA Interference / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins
D006514:Hepatitis B Surface Antigens; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C507007:Eri1 protein, mouse; D005092:Exonucleases; D005095:Exoribonucleases; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase