title: Targeting internal ribosome entry site (IRES)-mediated translation to block hepatitis C and other RNA viruses.
abstract: A number of RNA-containing viruses such as hepatitis C (HCV) and poliovirus (PV) that infect human beings and cause serious diseases use a common mechanism for synthesis of viral proteins, termed internal ribosome entry site (IRES)-mediated translation. This mode of translation initiation involves entry of 40S ribosome internally to the 5' untranslated region (UTR) of viral RNA. Cap-dependent translation of cellular mRNAs, on the other hand, requires recognition of mRNA 5' cap by the translation machinery. In this review, we discuss two inhibitors that specifically inhibit viral IRES-mediated translation without interfering with cellular cap-dependent translation. We present evidence, which suggest that one of these inhibitors, a small RNA (called IRNA) originally isolated from the yeast Saccharomyces cerevisiae, inhibits viral IRES-mediated translation by sequestering both noncanonical transacting factors and canonical initiation factors required for IRES-mediated translation. The other inhibitor, a small peptide from the lupus autoantigen La (called LAP), appears to block binding of cellular transacting factors to viral IRES elements. These results suggest that it might be possible to target viral IRES-mediated translation for future development of therapeutic agents effective against a number of RNA viruses including HCV that exclusively use cap-independent translation for synthesis of viral proteins.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, UCLA School of Medicine, University of California-Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA. dasgupta@ucla.edu
authors.forename: Asim
authors.initials: A
authors.lastname: Dasgupta
authors.forename: Saumitra
authors.initials: S
authors.lastname: Das
authors.forename: Raquel
authors.initials: R
authors.lastname: Izumi
authors.forename: Arun
authors.initials: A
authors.lastname: Venkatesan
authors.forename: Bhaswati
authors.initials: B
authors.lastname: Barat
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism; D016174:Hepacivirus / Q000235:genetics*; D006801:Humans; D014176:Protein Biosynthesis / Q000235:genetics*; D012328:RNA Viruses / Q000235:genetics*; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000502:physiology*; D000097585:SS-B Antigen
chemical_list: D020121:5' Untranslated Regions; D001324:Autoantigens; D012261:Ribonucleoproteins; D000097585:SS-B Antigen