• IMMUNE NETWORK
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• 제2권3호
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• pp.150-157
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• 2002

Background: Although Tat plays a role as a potent transactivator in the viral gene expression from the Human Immunodeficiency Virus type 1 long terminal repeat (HIV-1 LTR), it does not function efficiently in rodent cells implying the absence of a human specific factor essential for Tat-medicated transactivation in rodent cells. In previous experiments, we demonstrated that one of chimeric forms of TAR (transacting responsive element) of HIV-1 LTR compensated the restriction in rodent cells. Methods: To characterize the nature of the compensation, we tested the effects of several upstream binding factors of HIV-1 LTR by simple substitution, and also examined the role of the configuration of the upstream binding factor(s) indirectly by constructing spacing mutants that contained insertions between Sp1 and TATA box on Tat-mediated transactivation. Results: Human Sp1 had no effect whereas its associated factors displayed differential effects in human and rodent cells. In addition, none of the spacing mutants tested overcame the restriction in rodent cells. Rather, when the secondary structure of the chimeric HIV-1 TAR construct was destroyed, the compensation in rodent cells was disappeared. Interestingly, the proper interaction between Sp1 and TATA box binding proteins, which is essential for Tat-dependent transcription, was dispensable in rodent cells. Conclusion: This result suggests that the human-specific Tat cofactor acts to allow Tat to interact effectively in a ribonucleoprotein complex that includes Tat, cellular factors, and TAR RNA, rather than be associated with the HIV-1 LTR upstream DNA binding factors.

• Journal of Microbiology and Biotechnology
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• 제18권6호
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• pp.1044-1049
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• 2008

In order to study functional nucleotides in prototype foamy virus (PFV) DNA on specific recognition by PFV integrase (IN), we designed chimeric U5 long terminal repeat (LTR) DNA substrates by exchanging comparative sequences between human immunodeficiency virus type-1 (HIV-1) and PFV U5 LTRs, and investigated the 3'-end processing reactivity using HIV-1 and PFV INs, respectively. HIV-1 IN recognized the nucleotides present in the fifth and sixth positions at the 3'-end of the substrates more specifically than any other nucleotides in the viral DNA. However, PFV IN recognized the eighth and ninth nucleotides as distinctively as the fifth and sixth nucleotides in the reactions. In addition, none of the nucleotides present in the twelfth, sixteenth, seventeenth, eighteenth, nineteenth, and twentieth positions were not differentially recognized by HIV-1 and PFV INs, respectively. Therefore, our results suggest that the functional nucleotides that are specifically recognized by its own IN in the PFV U5 LTR are different from those in the HIV-1 U5 LTR in aspects of the positions and nucleotide sequences. Furthermore, it is proposed that the functional nucleotides related to the specific recognition by retroviral INs are present inside ten nucleotides from the 3'-end of the U5 LTR.

• BMB Reports
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• 제51권8호
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• Journal of Ginseng Research
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• 제35권4호
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• pp.413-420
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• 2011

We investigated whether Korean red ginseng (KRG) and highly active antiretroviral therapy (HAART) affect the frequency of gross deletion in 5'LTR/gag in 20 hemophiliacs. This study is a prospective study in 20 hemophiliacs who were infected with Korean subclade B of HIV-1 from two cash-paid plasma donors in 1990. Over a 13-year period, we obtained 436 amplicons of 5'LTR/gag genes by nested polymerase chain reaction using 147 peripheral blood mononuclear cells. Of the 436 amplicons, 92 (21.1%) showed gross deletion in 5'LTR/gag. Despite of a 2.3-fold higher monthly dose of KRG intake, the frequency of gross deletion in 5'LTR/gag (16.4%) was significantly decreased during HAART compared with 28.1% prior to HAART (p<0.01). Gross deletion in 5'LTR/gag was 10% more detected on KRG-therapy than prior to KRG-therapy (p<0.05). In addition, we also obtained 28 amplicons containing premature stop codon or isoleucine at initiation codon of 254 amplicons sequenced on KRG intake (7.5%) or HAART (13.6%) compared with 0% before KRG intake. These findings indicate that high frequency of gross deletion in 5'LTR/gag and genetic defects prior to HAART are significantly associated with KRG intake and the detection of gross deletion in 5'LTR/gag is decreased by HAART.

• BMB Reports
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• 제51권7호
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• pp.338-343
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• 2018

Transcription termination factor-1 (TTF-I) is an RNA polymerase 1-mediated transcription terminator and consisting of a C-terminal DNA-binding domain, central domain, and N-terminal regulatory domain. This protein binds to a so-called 'Sal box' composed of an 11-base pair motif. The interaction of TTF-I with the 'Sal box' is important for many cellular events, including efficient termination of RNA polymerase-1 activity involved in pre-rRNA synthesis and formation of a chromatin loop. To further understand the role of TTF-I in human immunodeficiency virus (HIV)-I virus production, we generated various TTF-I mutant forms. Through a series of studies of the over-expression of TTF-I and its derivatives along with co-transfection with either proviral DNA or HIV-I long terminal repeat (LTR)-driven reporter vectors, we determined that wild-type TTF-I downregulates HIV-I LTR activity and virus production, while the TTF-I Myb-like domain alone upregulated virus production, suggesting that wild-type TTF-I inhibits virus production and trans-activation of the LTR sequence; the Myb-like domain of TTF-I increased virus production and trans-activated LTR activity.

• 대한바이러스학회지
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• 제29권2호
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• pp.107-118
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• 1999

To characterize the molecular nature of human immunodeficiency virus (HIV)-1, we determined the full-length HIV-1 sequences from cultured peripheral blood mononuclear cells (PBMC) of a Korean long-term nonprogressor (LTNP). Without antiretroviral therapy, the individual has maintained CD4+ T counts over $500/{\mu}l$ from 1989 to 1999. Plasma viral RNA copy was 992 U/ml in 1998. Culture supernatant showed positive from culture days 9. A series of 9 overlapping PCR products were amplified from cultured PBMC and cloned About 9.2 kb from R of 5' LTR to R of 3' LTR was determined by automated sequencing. The G-to-A hypermutations were shown throughout the entire region. As a result of G to A hypermutations, premature stop codon was found in integrase coding region. Though there was no recombination between subtypes over all genomes, TATA box in both LTRs was TAAAA which is detected in subtype E instead of TATAA in subtype B. And, there were nucleotide GC insertion between $NF-{\kappa}B$ I and Sp1 III, and duplication of $TCF-1{\alpha}$ in LTR. We could not find any deletion of amino acid in Nef, Gag, Pol and Env gene. This study is the first report on molecular nature of full genomes of HIV-1 isolated in Korea.

• BMB Reports
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• 제51권6호
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• pp.290-295
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• 2018

Y-box binding protein 1 (YB-1) is a member of the cold-shock domain (CSD) protein superfamily. It participates in a wide variety of cellular events, including transcription, RNA splicing, translation, DNA repair, drug resistance, and stress responses. We investigated putative functions of YB-1 in HIV-1 replication. Functional studies using overexpression or knockdown of YB-1 in conjunction with transfection of proviral DNA showed that YB-1 enhances virus production. We found YB-1 regulates HIV-1 production by stimulating viral transcription using HIV-1 LTR sequence U3RU5 with Luciferase assay. We also identified a specific region from amino acids 1 to 324 of YB-1 as necessary for the participation of the protein in the production of virions.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 2007년도 춘계 학술대회
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• pp.17-17
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• 2007

• BMB Reports
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• 제33권4호
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• pp.337-343
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• 2000

The human immunodeficiency virus type 1 (HIV-1), transactivator of transcription (Tat), is one of the viral gene products that is essential for HIV-1 replication. The HIV-l Tat protein regulates transcription from an HIV-1 long terminal repeat (LTR) and affects the gene expression of cellular proteins during infection. In order to develop an expression system to overexpress and simply purify HIV-1 Tat proteins, the HIV-1 Tat coding sequences that contain one or two exons were amplified using PCR and cloned into a pET vector, which contains a consecutive stretch of six histidine residues at the amino-terminus. The reconstituted vectors were overexpressed in the E. coli strain and the soluble recombinant proteins were purified to be homogeneity in a single step by $Ni^{+2}-nitrilotriacetic$ acid Sepharose chromatography under nondenaturing conditions. Recombinant HIV-1 Tat proteins were shown to transactivate the HIV-1 LTR promoter in a dose-dependent manner when introduced into mammalian cells. In addition, treatment of human endothelial cells with purified Tat proteins resulted in a significant increase in the level of vascular cell adhesion molecule-1 (VCAM-1) expression. These results indicate that the recombinant HIV-1 Tat proteins are active in transactivating viral and cellular promoters. The expression and purification system described in this study will facilitate in characterizing the biological functions of the Tat proteins.

• BMB Reports
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• 제53권5호
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• pp.248-253
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• 2020

Gene expression in HIV-1 is regulated by the promoters in 5' long-terminal repeat (LTR) element, which contain multiple DNA regulatory elements that serve as binding sites for cellular transcription factors. YY1 could repress HIV-1 gene expression and latent infection. Here, however, we observed that virus production can be increased by YY1 over-expression and decreased under YY1 depleted condition by siRNA treatment. To identify functional domain(s) of YY1 activation, we constructed a number of YY1 truncated mutants. Our data show that full-length YY1 enhances the viral transcription both through U3 and U3RU5 promoters. Moreover, the C-terminal region (296-414 residues) of YY1 is responsible for the transcriptional upregulation, which could be enhanced further in the presence of the viral Tat protein. The central domain of YY1 (155-295 residues) does not affect LTR activity but has a negative effect on HIV-1 gene expression. Taken together, our study shows that YY1 could act as a transcriptional activator in HIV-1 replication, at least in the early stages of infection.