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F B Hoshino

Publications and source records attributed to F B Hoshino.

15 recordsLinked to original sources
PubMed2001

Ribosomal protein S5 interacts with the internal ribosomal entry site of hepatitis C virus.

Translational initiation of hepatitis C virus (HCV) genome RNA occurs via its highly structured 5' noncoding region called the internal ribosome entry site (IRES). Recent studies indicate that HCV IRES and 40 S ribosomal subunit form a stable binary complex that is believed to be important for the subsequent assembly of the 48 S initiation complex. Ribosomal protein (rp) S9 has been suggested as the prime candidate protein for binding of the HCV IRES to the 40 S subunit. RpS9 has a molecular mass of approximately 25 kDa in UV cross-linking experiments. In the present study, we examined the approximately 25-kDa proteins of the 40 S ribosome that form complexes with the HCV IRES upon UV cross-linking. Immunoprecipitation with specific antibodies against two 25-kDa 40 S proteins, rpS5 and rpS9, clearly identified rpS5 as the protein bound to the IRES. Thus, our results support rpS5 as the critical element in positioning the HCV RNA on the 40 S ribosomal subunit during translation initiation.

5' Untranslated Regions↗
PubMed2001

Interaction of poly(rC)-binding protein 2 with the 5'-terminal stem loop of the hepatitis C-virus genome.

The 5' noncoding region (NCR) of hepatitis C virus (HCV) contains an internal ribosome entry site for translation initiation. Cellular proteins (e.g. La, polypyrimidine tract-binding protein, and p25) that interact with HCV 5' NCR have been implicated in facilitating efficient internal initiation. The 5' NCR may also contain RNA structures and specific RNA sequences that interact with cellular proteins to promote RNA replication. UV crosslinking experiments revealed a 43-kDa cellular protein (p43) also interacts with the HCV 5' NCR. Further UV crosslinking experiments with deletion mutants of HCV 5' NCR demonstrated that p43 bound specifically to the 5'-terminal stem-loop of the HCV 5' NCR. Achromobactor proteinase I digests, competition experiments, and immunoprecipitation confirmed that p43 was identical to human poly(rC)-binding protein 2 (PCBP2). We prepared a PCBP2-immunodepleted rabbit reticulocyte lysate with an anti-PCBP2 antibody. Translation activity promoted by the HCV internal ribosome-entry site was the same in PCBP2-depleted lysates as in mock-depleted lysates. In conclusion, PCBP2 specifically interacted with the 5' terminus of HCV genome but had no effect on HCV translation. We speculate that PCBP2's interaction with HCV 5' NCR may be involved in the replication-initiation complex of HCV.

5' Untranslated Regions↗
PubMed2000

Heterogeneity found in the cagA gene of Helicobacter pylori from Japanese and non-Japanese isolates.

We analyzed cagA genes from Helicobacter pylori strains isolated from Japanese and non-Japanese individuals for differences that could be associated with variations in virulence. The cagA genes from Japanese isolates (n = 12) and non-Japanese American Type Culture Collection (ATCC) strains (n = 4) were sequenced and compared with three published sequences. Phylogenetic analysis resolved two distinct clusters with a genetic distance of 0.1602. Similarity plot analysis of the amino acid sequences identified two highly variable regions of which each was unique to the Japanese and non-Japanese isolates, respectively. Furthermore, nucleic acid sequence analysis revealed that the multiple repeated sequences present in cagA may have been generated by homologous recombination and/or misaligned replication to promote variation in the cagA gene products. Our data indicate that alleic variations in the H. pylori genome exist between isolates from Japanese and non-Japanese subjects and that distinct H. pylori populations may be circulating in different geographical regions. Phylogenetic analysis did not reveal any association of a specific CagA type with a particular disease. Although extensive alterations were found in the cagA gene, none of the isolates contained a prematurely terminated CagA protein. The cagA gene may be advantageous to H. pylori, possibly by aiding its escape from host immune recognition by antigen modulation. Thus, this ability to elude the host immune system may contribute to an increased risk for gastric disease.

Algorithms↗
PubMed1999

Specific interaction of a 25-kilodalton cellular protein, a 40S ribosomal subunit protein, with the internal ribosome entry site of hepatitis C virus genome.

Translation initiation of hepatitis C virus (HCV) RNA is controlled by an internal ribosome entry site (IRES) contained in 5' noncoding region (NCR) and in several nucleotides of the coding region. The ability of a 25-kilodalton cellular protein (p25) to bind the HCV 5' NCR is correlated with the efficiency of translation initiation of HCV RNA, indicating that this protein plays a critical role in HCV translation (S. Fukushi, C. Kurihara, N. Ishiyama, F. B. Hoshino, A. Oya, and K. Katayama, J Virol 71, 1662-1666, 1997). We have extended the study for identification of the IRES region required for p25 binding. For this purpose, we have performed UV cross-linking competition analyses using 5'- or 3'- deleted mutants of the HCV 5' NCR as competitor RNAs for binding of p25 to wild-type HCV 5' NCR. Competitor RNAs lacking nucleotides (nt) 47-74 or nt 279-331 did not inhibit p25 binding to the HCV IRES, indicating that these regions are necessary for interaction of the p25 and HCV IRES. Since p25 binding was not observed in the IRES elements of encephalomyocarditis virus and poliovirus in UV cross-linking competition analyses, the p25 binding may be specific for the HCV IRES. p25 bound to the HCV IRES was detected when a purified 40S ribosomal subunit was used for UV cross-linking experiment, indicating that p25 is one of 40S ribosomal subunit proteins. These results reveal an unique interaction between the 40S ribosomal subunit and HCV IRES to contribute to translation initiation of the HCV genome.

Base Sequence↗
PubMed1998

Full-length GBV-C/HGV genomes from nine Japanese isolates: characterization by comparative analyses.

The genomes of nine GBV-C/HGV isolates from Japanese chronic hepatitis patients were fully sequenced and characterized. They shared 85% nucleotide sequence homology with previously characterized isolates from the US and West Africa. Homology studies and phylogenetic analyses showed that the Japanese isolates formed a third group distinct from the established groups 1 and 2. The genetic distances between the three groups of GBV-C/HGV were very similar to the distances between the two classical swine fever virus (CSFV) serotypes, which suggested that they might belong to a separate GBV-C/HGV serotype. Plot similarity analysis comparing the three groups exposed relatively conserved terminal non-coding regions. Hairpin structures predicted in the Japanese isolates are probably involved in viral replication. The region coding E1-E2-NS-2 showed the least similarity (80%); in HCV the similarity here is only 50% due to its hypervariability. NS-3 and NS-5b that respectively encode the helicase/protease and RNA-dependent RNA polymerase, had a high degree of amino acid homology, suggesting a high degree of functional constraint in this region. The NS-5b nucleotide sequence was highly conserved perhaps because of constraints from RNA secondary structure and/or an open reading frame in the negative strand.

Base Sequence↗
PubMed1997

New variant groups identified from HGV isolates.

We have determined the primary sequence of the 5' noncoding region (5' NCR) and putative helicase regions (NS-3) of hepatitis G virus (HGV) and GB virus C (GBV-C) that were isolated in Japan from suspected cases of nonA-nonB and/or nonA-nonB-nonC viral hepatitis by using RT-PCR, and we compared the newly isolated sequences with three established isolates. The addition of a "G" residue was found at the 5' terminus of all 8 Japanese isolates. These isolates were more clearly distinguished from the prototype viruses by comparison with the 5' NCR sequence than by comparison with the NS-3 region. Our results suggested that at least three distinct genomic variants of HGV exist. Genotyping of HGV by using RT-PCR based on the sequence of the 5' NCR seems highly feasible.

Base Sequence↗
PubMed1997

The sequence element of the internal ribosome entry site and a 25-kilodalton cellular protein contribute to efficient internal initiation of translation of hepatitis C virus RNA.

Translation of hepatitis C virus (HCV) RNA is initiated by internal entry of ribosomes into the 5' noncoding region (NCR). This process depends on genomic elements within the 5' NCR called the internal ribosome entry site (IRES) and may involve host factors. The alpha-branch structure (nucleotides 47 to 67) of the HCV IRES is considered a cis-acting element critical for translation initiation because it is indispensable for translation in vitro (S. Fukushi, K. Katayama, C. Kurihara, N. Ishiyama, F. B. Hoshino, T. Ando, and A. Oya, Biochem. Biophys. Res. Commun. 199:425-432, 1994). In order to further characterize the function of the alpha-branch, we determined whether sequence exchange within the alpha-branch had any effect on translation initiation. An in vitro translation study revealed that the stem sequences of this region played an important role in efficient IRES function. In addition to several HeLa cell proteins, which had a binding affinity for the 5' NCR, a novel 25-kDa protein that specifically interacted with the HCV IRES was discovered. The binding affinity of the 25-kDa protein for the 5' NCR was correlated with the efficiency of translation initiation of HCV RNA, indicating a critical role for the 25-kDa protein in HCV translation.

Animals↗
PubMed1996

Nucleotide sequence of the 5' noncoding region of hepatitis G virus isolated from Japanese patients: comparison with reported isolates.

The nucleotide sequences of the 5' noncoding region (NCR) of hepatitis G virus (HGV) from sera of Japanese patients were determined. Among these isolates, there was a high degree (> 96.9%) of sequence identity, whereas identity with previously reported GB virus-C or HGV strains was low (> 87.0%). Phylogenetic analyses showed that the HGV strains from Japanese patients clustered in groups distantly separated from previously reported strains. Among the Japanese HGV isolates, the genetic distances corresponded to subtype differences observed within hepatitis C virus (HCV) isolates, whereas the differences between the Japanese isolates and the prototypes corresponded to genetic distances observed between HCV genotypes. The Japanese HGV isolates found in this study should be placed in a new genotype distinct from previously described isolates.

Base Sequence↗
PubMed1995

A preadipocyte clonal line from bovine intramuscular adipose tissue: nonexpression of GLUT-4 protein during adipocyte differentiation.

A clonal bovine intramuscular preadipocyte (BIP) line has been established from the intramuscular white adipose tissue of the M. longissimus thoracis in each of three Japanese Black cattle. Exponentially growing BIP cells exhibited a fibroblastic appearance. Adipocyte differentiation was initiated by treating confluent BIP cells with differentiation medium containing insulin and dexamethasone. Small lipid droplets appeared 5-6 days after stimulation and occupied a large fraction of the cell volume at 10 days and beyond. During the adipose conversion, the incorporation of acetate to the cells gradually increased by 10-fold and reached a maximum at day 5. However, incorporation of glucose increased only 3-folds prior to this conversion, even though GLUT-1 level increased by 13-fold at day 7. GLUT-4, on the other hand, was not detected during the course of differentiation. These results suggested that adipose tissue metabolisms in ruminants were different from that of non-ruminants.

Acetates↗
PubMed1995

Characterization of the hog cholera virus 5' terminus.

Hog cholera virus (HoCV) 5' terminus of the ALD and GPE(-) strains were analyzed by using rapid amplification of cDNA end method (5'RACE). An additional nine nucleotides were found at the 5' termini of genomic RNA in the ALD and GPE(-) strains of HoCV. These nine nucleotides were also conserved in BVDV and were suggested to form a hairpin structure at the 5' terminus by computer-assisted analysis. It seems possible that the secondary structure and/or the 5' terminus sequence has a significant role in the HoCV virus genome.

Animals↗
PubMed1994

GLUT2 expression in the rat retina: localization at the apical ends of Müller cells.

In order to understand the molecular basis of glucose regulation supporting visual function, this study examined the presence of GLUT2, a facilitated-diffusion glucose transporter isoform, and delineated its localization in the rat retina. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated the presence of GLUT2 mRNA, and immunoblot analysis using polyclonal antibody specific to rat GLUT2 revealed a band at a molecular weight of approximately 60 kDa, indicating the presence of GLUT2 protein in the rat retina. Fluorescence and electron microscopy localized GLUT2 expression to the apical ends of Müller cells that face the inter-photoreceptor space. These findings suggest that GLUT2 on Müller cells may control intra-retinal glucose homeostasis by performing both anterior and posterior glucose transport within the rat retina. This is the first study to provide evidence that GLUT2 is present in the mammalian central nervous system and indicates that GLUT2 may have local glucose homeostatic functions within the retina in addition to its role in the regulation of systemic blood glucose level.

Animals↗
PubMed1994

Complete 5' noncoding region is necessary for the efficient internal initiation of hepatitis C virus RNA.

The mechanism of translational initiation by the 5' noncoding region (5'NCR) of hepatitis C virus (HCV) genome was analyzed. Using an in vitro translation system with artificial RNA containing a modified 5' NCR of HCV under the various KCl conditions, nucleotides (nt.) 62 to 341 of the HCV 5'NCR were not functional as an internal ribosome entry site (IRES). However, the full-length 5'NCR (nt. 1 to 341) produced an efficient internal initiation. To identify the essential region of the HCV-IRES, various mutants were produced in which stem-loops, predicted by secondary structure analysis of the HCV 5'NCR, were deleted. These constructs were analyzed by in vitro translation. Comparison of translation efficiency among these mutants suggested that the alpha- or both alpha- and beta-branches of domain II are essential for efficient translation. Moreover, the formation of correct secondary structure of IRES seems to be stabilized by the presence of domain I in 5'NCR. Furthermore, the uncapped 5'NCR of HCV promotes translation more efficiently than capped truncated 5'NCR constructs. Our results strongly suggested that complete 5'NCR containing all stem-loop structures is necessary for initiation by HCV-IRES.

Base Sequence↗