BACKGROUND: Translation of the hepatitis C virus (HCV) is mediated by an internal ribosome entry site (IRES). Here, we analyzed the functional relevance of La protein for replication of HCV using an infectious HCV clone, JFH-1. METHODS: A single-nucleotide mutation from A to U was introduced at the 338th nucleotide in the stem-loop domain IV structure of HCV IRES, which stabilized stem-loop IV and abolished translation and replication of JFH-1 almost completely. RESULTS: During JFH-1 replication, translation initiation factors required for HCV IRES activity, including La protein, polypyrimidine tract binding protein (PTB), PSMA7, and PCBP2, were significantly induced in Huh-7.5 cells. Interestingly, JFH-1 infection increased telomerase activity and induced the expression of human telomerase RNA (hTR) in Huh-7.5 cells. In 37 tissue specimens from patients with chronic hepatitis C, La protein significantly correlated with the representative essential telomerase components hTR, p23, and HSP90 (P<.001). Recombinant adenovirus that expressed short-hairpin RNA against La protein successfully suppressed the levels of La protein and core protein of JFH-1 to 30% of that in the control cells. CONCLUSIONS: HCV infection might be strongly related to telomerase activity in the liver through La protein induction. Inhibition of La protein substantially repressed JFH-1 replication; therefore, La protein is a potential therapeutic target for HCV.
BACKGROUND: Translation of the hepatitis C virus (HCV) is mediated by an internal ribosome entry site (IRES). Here, we analyzed the functional relevance of La protein for replication of HCV using an infectious HCV clone, JFH-1. METHODS: A single-nucleotide mutation from A to U was introduced at the 338th nucleotide in the stem-loop domain IV structure of HCV IRES, which stabilized stem-loop IV and abolished translation and replication of JFH-1 almost completely. RESULTS: During JFH-1 replication, translation initiation factors required for HCV IRES activity, including La protein, polypyrimidine tract binding protein (PTB), PSMA7, and PCBP2, were significantly induced in Huh-7.5 cells. Interestingly, JFH-1 infection increased telomerase activity and induced the expression of human telomerase RNA (hTR) in Huh-7.5 cells. In 37 tissue specimens from patients with chronic hepatitis C, La protein significantly correlated with the representative essential telomerase components hTR, p23, and HSP90 (P<.001). Recombinant adenovirus that expressed short-hairpin RNA against La protein successfully suppressed the levels of La protein and core protein of JFH-1 to 30% of that in the control cells. CONCLUSIONS:HCV infection might be strongly related to telomerase activity in the liver through La protein induction. Inhibition of La protein substantially repressed JFH-1 replication; therefore, La protein is a potential therapeutic target for HCV.
Authors: Sergey M Dibrov; Jerod Parsons; Maia Carnevali; Shu Zhou; Kevin D Rynearson; Kejia Ding; Emily Garcia Sega; Nicholas D Brunn; Mark A Boerneke; Maria P Castaldi; Thomas Hermann Journal: J Med Chem Date: 2013-11-05 Impact factor: 7.446