Polymorphisms in the transcribed 3' untranslated region of eukaryotic genes.

In this review we present preliminary evidence for a new class of polymorphism that may be used in a systematic way to map cDNAs efficiently and to expedite the construction of a high-resolution genetic map of the human genome. Ultimately, transcribed 3' untranslated polymorphisms will warrant further study because they should be widely distributed throughout the genome within transcribed sequences, and they can be readily identified as a result of cDNA cloning and sequencing. Furthermore, these markers should be universally available on the basis of the sequence data and highly useful in linkage analyses.     

The inhibitory effect of the 5' untranslated region of muscle acylphosphatase mRNA on protein expression is relieved during cell differentiation

Previous experiments suggested that the upstream AUG triplet present in the 5' untranslated region (UTR) of muscle acylphosphatase mRNA is involved in the regulation of protein expression. In this paper, we study the involvement of the 5'UTR secondary structure and upstream peptide on mRNA stability and protein translation. Our data, obtained using deletion and frame-shift mutants, demonstrate that the 5'UTR controls protein expression regulating translation together with mRNA stability. Furthermore, we demonstrate that the inhibitory effect of the 5'UTR of muscle acylphosphatase is relieved during the differentiation process in agreement with previous data reporting an increase of acylphosphatase content during cell differentiation. Finally, UV cross-linking experiments show that specific mRNA-binding proteins are associated with the 5'UTR of the muscle acylphosphatase mRNA.     

3′端非翻译区对重组人肝细胞生成素表达不均一性的影响

在工程菌pBV－hHPO／DH5α中表达的人肝细胞生成素（hHPO）以两种分子形式存在,经分析可能是由于表态质粒中hHPO基因的终止密码子TAG的通读造成的。表达载体经改构后,去掉质粒子hHPO基因终止密码子后的非翻译区,采用TAA作终止密码子,结果改构后的表达载体只表达单一形式的hHPO。     

Both the 5' and 3' LTRs of FIV contain minor RNA encapsidation determinants compared to the two core packaging determinants within the 5' untranslated region and gag

This study was undertaken to address the role of feline immunodeficiency virus (FIV) long terminal repeats (LTR) as potential packaging determinants. A number of studies in the recent past have clearly demonstrated that the core packaging determinants of FIV reside within at least two distinct regions at the 5' end of the viral genome, from R in the 5' LTR to approximately 150 bp within the 5' untranslated region (5' UTR) and within the first 100 bp of gag; however, there have been conflicting observations as to the role of the LTR regions in packaging and whether they contain the principal packaging determinants of FIV. Using a semi-quantitative RT-PCR approach on heterologous non-viral vector RNAs in an in vivo packaging assay, this study demonstrates that the principal packaging determinants of FIV reside within the first 150 bp of 5' UTR and 100 bp of gag (the two core regions) and not the viral 5' LTR. Furthermore, it shows that in addition to the 5' LTR, the 3' LTR also contains packaging determinants, but of a less significant nature compared to the core packaging determinants. This study defines the relative contribution of the various regions implicated in FIV genomic RNA packaging, and reveals that like other primate lentiviruses, the packaging determinants of FIV are multipartite and spread out, an observation that has implications for safer and more streamlined design of FIV-based gene transfer vectors.     

A three-nucleotide insertion in the H stem-loop of the 5' untranslated region of Theiler's virus attenuates neurovirulence.

The highly structured 5' untranslated region (5' UTR) of Theiler's murine encephalomyelitis virus is involved in cap-independent translation of the viral RNA. Previously, we reported that the bicistronic mRNA chloramphenicol acetyltransferase-5' UTR-luciferase (Luc) efficiently expressed Luc both in a rabbit reticulocyte lysate and when transfected into BHK-21 cells. Insertion of 3 nucleotides at position 665 in the 5' UTR of this bicistronic mRNA resulted in greatly reduced Luc expression in BHK-21 cells but had little effect on expression of Luc in rabbit reticulocyte lysate. This mutation was also introduced into a virulent Theiler's murine encephalomyelitis virus chimera, Chi-VL. The kinetics of viral RNA and protein synthesis and virus production in BHK-21 cells were slower for the mutant chimera [Chi-VL(IN668)] than for Chi-VL; however, the final virus yields were comparable. Intracerebral inoculation of mice with the chimeras revealed that Chi-VL(IN668) was completely attenuated in neurovirulence. The reduced neurovirulence of Chi-VL(IN668) may be ascribed to its reduced growth in the central nervous system, most likely due to an impaired ability to synthesize viral proteins.