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The complete nucleotide sequence ofthe genome of the type 1 poliovirus vaccine strain (LSc,2ab) was determined by using molecular cloning and rapid sequence analysis techniques. The restriction fragments of double-stranded cDNA synthesized from the vaccine strain RNA were inserted into the adequate sites of cloning vector pBR322. Sequence analysis of the cloned DNAs revealed that the virion RNA molecule was 7,441 nucleotides long and polyadenylylated at the 3' terminus. When the nucleotide sequence was compared with that of the genome of the virulent parental strain (Mahoney), 57 base substitutions were observed to be scattered all over the genome. Of these, 21 resulted in amino acid changes in a number of viral proteins. A cluster of amino acid changes is located in the viral coat proteins, especially in the NH2-terminal halfofthe viral capsid protein VP1.These results may imply that the mutations in the VP1 coding region contribute to attenuation.The genome ofpoliovirus is a single-stranded RNA with positive polarity, in which all of the viral genetic information is stored (1). This genomic RNA is composed of =7,500 nucleotides, polyadenylylated at the 3' terminus (2) and covalently attached to a genome-linked protein (VPg) at the 5' terminus (3-6). Re PVl(Sab)] is a live vaccine strain derived from the PV1(M) by spontaneous mutations during the attenuation process (9, 10).To determine the molecular basis for the biological differences between virulent and attenuated poliovirus strains, the sequences of large and unique RNase Ti-and A-resistant ohigonucleotides of PV1(M) and PV1(Sab) have been compared. We have shown that mutations detected by oligonucleotide analysis were caused by single base substitutions and appeared to be scattered all over the genome (11).For further comparative sequence studies, the restriction fragments obtained from double-stranded cDNA of the PV1(Sab) genome have been cloned (12). We report here the complete 7,441-nucleotide sequence of the PV1(Sab) genome, and the mutation sites were identified by comparison of our sequence with the known sequence of the PV1(M) genome (7,8).

Thioredoxin reductase (TrxR) is a selenoprotein that catalyzes the reduction of the active site disulfide of thioredoxin (Trx), which regulates the redox status of the cells. In the present study, we found that TrxR1, one of the three TrxR isozymes, was induced by cadmium as well as tumor necrosis factor alpha (TNFalpha) in bovine arterial endothelial cells (BAEC), and investigated the mechanism of cadmium-induced TrxR1 expression. We here showed that cadmium, differently from TNFalpha, enhanced the promoter activity of the 5'-flanking region of human TrxR1 gene (nucleotides -1692 to +49). Deletion and site-directed mutation of antioxidant responsive element (ARE) (nucleotides -62 to -48) in this region abolished the response to cadmium. Overexpression of NF-E2-related factor-2 (Nrf2) augmented the TrxR1 promoter activity. In contrast, overexpression of the dominant negative mutant of Nrf2 suppressed cadmium-induced activation of TrxR1 promoter through the ARE. Chromatin immunoprecipitation (ChIP) assays showed that anti-Nrf2 antibody precipitated ARE from the chromatin of the cadmium-treated cells. These results indicated that cadmium-induced TrxR1 gene expression is mediated by the activation of Nrf2 transcription factor and its binding to ARE in the TrxR1 gene promoter. We further found that in addition to cadmium, the activators of Nrf2, such as diethyl maleate (DEM) and arsenite, induced both TrxR1 and Trx gene expression in BAEC. Nrf2 might play an important role in the regulation of the cellular Trx system consisting of Trx and TrxR.

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Metallothionein (MT), a low molecular weight, cysteine-rich metal binding protein, has been associated with cytoprotection from heavy metals and cellular oxidants. As MT has the ability to scavenge hydroxyl radicals, MT may control intracellular redox status. In the present study, we examined whether MT regulates the activity of nuclear factor-U UB (NF-U UB), which is one of the redox-regulated transcription factors, using the MT null embryonic cell lines established from MT null mice. We first found that tumor necrosis factor (TNF)-induced activation of the binding of NF-U UB protein to DNA in wild type MT+/+ cells was lower than that in MT3 3/3 3 cells. The NF-U UB activation in MT-expressing cells established from MT3 3/3 3 cells by the transfection of mouse MT-I gene was also significantly lower than that in MT3 3/3 3 cells. In addition, transfection of the MT gene inhibited TNF-induced IU UB degradation and suppressed NF-U UB-dependent gene expression induced by TNF. These results demonstrate that MT may function as a negative regulator of NF-U UB activity.z 1999 Federation of European Biochemical Societies.