%0 Journal Article
%T Refractoriness of hepatitis C virus internal ribosome entry site to processing by Dicer in vivo
%A Dominique L Ouellet
%A Isabelle Plante
%A Vincent Boissonneault
%A Cherifa Ayari
%A Patrick Provost
%J Journal of Negative Results in BioMedicine
%D 2009
%I BioMed Central
%R 10.1186/1477-5751-8-8
%X We report that HCV IRES can be recognized and processed into small RNAs by the human ribonuclease Dicer in vitro. Furthermore, we identify domains II, III and VI of HCV IRES as potential substrates for Dicer in vitro. However, maintenance of the functional integrity of the HCV IRES in response to Dicer overexpression suggests that the structure of the HCV IRES abrogates its processing by Dicer in vivo.Our results suggest that the HCV IRES may have evolved to adopt a structure or a cellular context that is refractory to Dicer processing, which may contribute to viral escape of the host RNA silencing machinery.Hepatitis C virus (HCV), a member of the Flaviviridae family, is a positive-strand RNA virus that establishes a persistent infection in the liver, leading to the development of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma [1]. HCV is one of the main causes of liver-related morbidity and mortality [2]. Its ~9,6-kilobase (kb) RNA genome, which is flanked at both termini by conserved, highly structured untranslated regions (UTRs), encodes a polyprotein processed by host and viral proteases to produce the structural (core, E1, E2-p7) and non-structural (NS2, NS3, NS4A, NS4B, NS5A, NS5B) proteins of the virus [3,4]. Located in its 5'UTR, the internal ribosome entry site (IRES) of HCV essentially controls translation initiation [5-8] in a process involving cellular [9] as well as viral [10-14] proteins. The HCV IRES contains several double-stranded RNA (dsRNA) regions forming stem-bulge-loop structures [15,16] analogous to that of microRNA precursors (pre-miRNAs).Known to originate from Drosha processing of primary miRNAs (pri-miRNAs) in the nucleus [17], pre-miRNAs are the endogenous substrates of the ribonuclease III (RNase III) Dicer into the cytoplasm. Involved in the microRNA (miRNA)-guided RNA silencing pathway, Dicer converts pre-miRNAs into ~21 to 23-nucleotide (nt) RNA guide sequences [18,19], referred to as miRNAs. These short regulatory
%U http://www.jnrbm.com/content/8/1/8