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Internal Ribosomal Entry Site (internal + ribosomal_entry_site)
Selected AbstractsIntroduction of NS5A mutations enables subgenomic HCV replicon derived from chimpanzee-infectious HC-J4 isolate to replicate efficiently in Huh-7 cellsJOURNAL OF VIRAL HEPATITIS, Issue 5 2004S. Maekawa Summary., Hepatitis C virus (HCV) subgenomic replicon has been reported to replicate efficiently and continuously in human hepatoma Huh-7 cells. To extend the previous results to other isolated HCV clones, we constructed another HCV replicon from HC-J4, one of chimpanzee-infectious HCV clones. An HCV replicon derived from HC-J4 (RpJ4) consists of HCV-5, untranslated region, neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural region, NS3 to NS5B, and HCV-3, untranslated region. The adaptive mutations known to be required for HCV-Con1 replicon were introduced in RpJ4 replicon, aa.(amino acids number according to HC-J4) 2197 serine to proline, deletion of serine at aa.2201, and aa.2204 serine to isoleucine (RpJ4-S2197P, RpJ4-S22001del, and RpJ4-S2204I). RpJ4/ISDR mutant and RpJ4-S2201del/ISDR mutant were also constructed by introducing six amino acid mutations into the interferon sensitivity determining region (ISDR). After transfection into Huh-7 cells and G418 selection, RpJ4 and RpJ4/ISDR mutants did not produce any colony. In contrast, G418-resistant cells were transduced efficiently by RpJ4-S2197P, RpJ4-S2204I, RpJ4-S2201del and RpJ4-S2201del/ISDR mutant, with the RpJ4-S2201del/ISDR mutant being most efficient. Hence the HCV replicon derived from HC-J4 can replicate efficiently following the introduction of adaptive mutations into the upstream region of ISDR. Moreover, additional introduction of mutations into ISDR further enhanced its replication. These findings demonstrate that the genetic structure of the NS5A domain is critical in HCV replications. [source] Role of adult living donor liver transplantation in patients with hepatitis CLIVER TRANSPLANTATION, Issue 10C 2003Gregory T. Everson Key points 1. Living donor liver transplantation (LDLT) is an option for patients with end-stage liver disease or hepatoma caused by chronic hepatitis C. 2. Reports from some, but not all, transplant centers indicate that hepatitis C may recur earlier, recurrence may be more severe, and graft loss caused by recurrent hepatitis C may be more frequent in LDLT compared with cadaveric transplantation. 3. Several unique characteristics of LDLT (versus cadaveric transplantation) may favor severe recurrence of hepatitis C. These include an increase in genetic similarity between donor and recipient, higher degree of HLA matching, greater systemic bioavailability of immunosuppressive agent, and hepatic regeneration. 4. Hepatic regeneration may promote the acceleration and severity of recurrent hepatitis C by enhancement of hepatitis C viral uptake by hepatocytes through stimulation of the low-density lipoprotein receptor and increase in activity of the internal ribosomal entry site. [source] Crystallization and preliminary X-ray diffraction analysis of the MIF4G domain of DAP5ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2010Filipp Frank Death-associated protein 5 (DAP5) is a member of the eIF4G family of scaffolding proteins that mediate cap-independent translation initiation by recruiting the translational machinery to internal ribosomal entry sites (IRESs) on mRNA. The MIF4G domain of DAP5 directly interacts with the eukaryotic initiation factors eIF4A and eIF3 and enhances the translation of several viral and cellular IRESs. Here, the crystallization and preliminary X-ray diffraction analysis of the MIF4G domain of DAP5 is presented. [source] Novel CNBP- and La-based translation control systems for mammalian cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003Stefan Schlatter Abstract Throughout the development of Xenopus, production of ribosomal proteins (rp) is regulated at the translational level. Translation control is mediated by a terminal oligopyrimidine element (TOP) present in the 5, untranslated region (UTR) of rp -encoding mRNAs. TOP elements adopt a specific secondary structure that prevents ribosome-binding and translation-initiation of rp -encoding mRNAs. However, binding of CNBP (cellular nucleic acid binding protein) or La proteins to the TOP hairpin structure abolishes the TOP-mediated transcription block and induces rp production. Based on the specific CNBP-TOP/La-TOP interactions we have designed a translation control system (TCS) for conditional as well as adjustable translation of desired transgene mRNAs in mammalian cells. The generic TCS configuration consists of a plasmid encoding CNBP or La under control of the tetracycline-responsive expression system (TETOFF) and a target expression vector containing a TOP module between a constitutive PSV40 promoter and the human model product gene SEAP (human secreted alkaline phosphatase) (PSV40 -TOP- SEAP -pA). The TCS technology showed excellent SEAP regulation profiles in transgenic Chinese hamster ovary (CHO) cells. Alternatively to CNBP and La, TOP-mediated translation control can also be adjusted by artificial phosphorothioate anti-TOP oligodeoxynucleotides. Confocal laser-scanning microscopy demonstrated cellular uptake of FITC-labeled oligodeoxynucleotides and their localization in perinuclear organelles within 24 hours. Besides their TOP-based translation-controlling capacity, CNBP and La were also shown to increase cap-independent translation from polioviral internal ribosomal entry sites (IRES) and La alone to boost cap-dependent translation initiation. CNBP and La exemplify for the first time the potential of RNA-binding proteins to exert translation control of desired transgenes and to increase heterologous protein production in mammalian cells. We expect both of these assets to advance current gene therapy and biopharmaceutical manufacturing strategies. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 1,12, 2003. [source] | ||||||||||