Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that the p75 isoform of the transcriptional co-activator lens epithelium-derived growth factor (LEDGF) interacts tightly with human immunodeficiency virus (HIV)-1 integrase (IN) and is essential for nuclear targeting of this protein in human cells (Cherepanov, P., Maertens, G., Proost, P., Devreese, B., Van Beeumen, J., Engelborghs, Y., De Clercq, E., and Debyser, Z. (2003) J. Biol. Chem. 278, 372-381; Maertens, G., Cherepanov, P., Pluymers, W., Busschots, K., De Clercq, E., Debyser, Z., and Engelborghs, Y. (2003) J. Biol. Chem. 278, 33528-33539). Here the interaction between recombinant LEDGF/p75 and HIV-1 IN was examined in a pull-down binding test. LEDGF/p75 was shown to increase the solubility of HIV-1 IN. Next, fluorescent correlation spectroscopy was used to measure the interaction of LEDGF/p75 or the complex of HIV-1 IN and LEDGF/p75 with a specific double-stranded DNA oligonucleotide. Whereas LEDGF/p75 displayed only a moderate affinity for DNA, it strongly promoted the binding of HIV-1 IN to DNA. This effect was specific for the p75 isoform of LEDGF and was not seen with p52. In the pull-down assay LEDGF/p75 interacted with HIV-1, HIV-2, and feline immunodeficiency virus IN, but not with the IN of human T-cell lymphotropic virus type 2, Moloney murine leukemia virus, or Rous sarcoma virus. These results strongly suggest that the interaction of LEDGF/p75 with IN is specific to lentiviridae. LEDGF/p75 stimulated the binding of HIV-1 and HIV-2 IN, but not Moloney murine leukemia virus or Rous sarcoma virus IN, to an aspecific DNA. These results provide supporting evidence for our hypothesis that LEDGF/p75 plays a role in the tethering of lentiviral IN to the chromosomal DNA.
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PMID:The interaction of LEDGF/p75 with integrase is lentivirus-specific and promotes DNA binding. 1574 13

Recently we described the interaction of human immunodeficiency virus type 1 (HIV-1)1 integrase (IN) with a cellular protein, lens epithelium-derived growth factor/transcription co-activator p75 (LEDGF/p75). We now present the study of the diffusion behavior of the three independent domains of IN and LEDGF/p75 using fluorescence correlation microscopy (FCM). We show that diffusion in the cell of the different enhanced green fluorescent protein (EGFP) fusion proteins is described by two components with different fractions and that the average parameters in the nucleus are comparable with those in the cytoplasm. In addition, we demonstrate that specific interaction between EGFP-fused HIV-1 IN and LEDGF/p75 results in a shift in diffusion coefficient (D). The opposite shift was observed in an IN-deletion mutant that does not exhibit LEDGF/p75 binding or in a LEDGF/p75 knock-down experiment using siRNA. We thus demonstrate that protein-protein interactions can be studied in living cells, using single-color FCM (scFCM).
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PMID:Measuring protein-protein interactions inside living cells using single color fluorescence correlation spectroscopy. Application to human immunodeficiency virus type 1 integrase and LEDGF/p75. 1578 49

To achieve productive infection, the reverse transcribed cDNA of human immunodeficiency virus type 1 (HIV-1) is inserted in the host cell genome. The main protein responsible for this reaction is the viral integrase. However, studies indicate that the virus is assisted by cellular proteins, or co-factors, to achieve integration into the infected cell. The barrier-to-autointegration factor (BAF) might prevent autointegration. Its ability to bridge DNA and the finding that the nuclear lamina-associated polypeptide-2alpha interacts with BAF suggest a role in nuclear structure organization. Integrase interactor 1 was found to directly interact with HIV-1 integrase and to activate its DNA-joining activity, and the high mobility group chromosomal protein A1 might approximate both long terminal repeat (LTR) ends and facilitate integrase binding by unwinding the LTR termini. Furthermore, the lens-epithelium-derived growth factor (LEDGF; also known as p75) seems to tether HIV-1 integrase to the chromosomes. Although a direct role in integration has only been demonstrated for LEDGF/p75, to date, each validated cellular co-factor for HIV-1 integration could constitute a promising new target for antiviral therapy.
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PMID:Cellular co-factors of HIV-1 integration. 1640 35

After identifying the interaction between the transcriptional coactivator lens epithelium-derived growth factor (LEDGF/p75) and the human immunodeficiency virus type 1 (HIV-1) integrase (IN), we have now investigated the role of LEDGF/p75 during HIV replication. Transient small interfering RNA-mediated knockdown of LEDGF/p75 in HeLaP4 cells resulted in a three- to fivefold inhibition of HIV-1 (strain NL4.3) replication. Quantitative PCR was used to pinpoint the replication block to the integration step. Next, polyclonal and monoclonal HeLaP4-derived cell lines were selected with a stable knockdown of LEDGF/p75 mediated by a lentiviral vector (lentivector) encoding a short hairpin RNA (shRNA) targeting this protein. Cell lines stably transduced with a lentivector encoding an unrelated hairpin or a double-mismatch hairpin served as controls. Again, a two- to fourfold reduction of HIV-1 replication was observed. The extent of LEDGF/p75 knockdown closely correlated with the reduction of HIV-1 replication. After the back-complementation of LEDGF/p75 in the poly- and monoclonal knockdown cell lines using an shRNA-resistant expression plasmid, viral replication was restored to nearly wild-type levels. The Q168A mutation in integrase has been shown to interfere with the interaction with LEDGF/p75 without reducing the enzymatic activity. Transduction by HIV-1-derived lentivectors carrying the Q168A IN mutant was severely hampered, pointing again to a requirement for LEDGF/p75. Altogether, our data validate LEDGF/p75 as an important cellular cofactor for HIV integration and as a potential target for antiviral drug development.
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PMID:Transient and stable knockdown of the integrase cofactor LEDGF/p75 reveals its role in the replication cycle of human immunodeficiency virus. 1643 44

Transcriptional co-activator p75 is implicated in human cancer, autoimmunity and replication of human immunodeficiency virus type 1 (HIV-1) as a dominant integrase-interacting protein. Although characterized as chromatin associated, the normal biological role(s) of p75 remains fairly unclear. To gain insight into p75 function, we have characterized its cellular binding partners and report that JPO2, a recently identified Myc-binding protein, associates with p75 in vitro and in vivo. The pseudo HEAT repeat analogous topology (PHAT) domain of p75, which mediates its interaction with integrase, also mediates the interaction with JPO2, and recombinant integrase protein competes with JPO2 protein for binding to p75 in vitro. JPO2 binds p75 through a 61-residue (amino acids 58-119) region that is distinct from its Myc-interacting domain. In cells, JPO2 and p75 co-localize throughout the cell cycle, and both proteins concentrate on condensed chromosomes during mitosis. Strikingly, the association of JPO2 with chromatin strictly depends upon p75, similar to that of ectopically expressed integrase. Also similar to its effect on integrase, p75 stabilizes intracellular steady-state levels of JPO2 protein. Our results suggest a role for p75 in the Myc regulatory network, and indicate that p75 is a general adaptor protein tethering divergent factors to chromatin through its versatile integrase-binding domain.
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PMID:Transcriptional co-activator p75 binds and tethers the Myc-interacting protein JPO2 to chromatin. 1673 38

Long-term use of antiretroviral nucleoside reverse transcriptase inhibitors (NRTIs) as therapy for human immunodeficiency virus-1 (HIV-1) infection is limited by mitochondrial toxicity. Here we document mitochondrial pathology during the long-term culture of human HeLa cells in the presence or absence of the NRTI Zidovudine(R) (AZT, 800 muM) for up to 77-passages (p), with samples taken at early (p5-p11), middle (p36 and p37), and late (p70-p77) passages. Samples were analyzed for changes in mitochondrial morphology, mitochondrial (mt)DNA quantity, nuclear and mitochondrial gene expression, and mitochondrial membrane potential. Mitochondria showed abnormal proliferation at p5 and abnormal morphology >/=p36. mtDNA quantity was increased at p5 and p11, and 65% depleted at p71. Hierarchical clustering of nuclear gene expression, examined at p37 by the NCI cDNA microarray in AZT-exposed cells, showed down-regulation of 13 out of 16 lipid-metabolizing genes, and up-regulation of most oxidative phosphorylation (OXPHOS) genes. OXPHOS genes encoded by mtDNA, examined at p5, p36, and p75 using the Mitochondrial Gene Mini Array, revealed up-regulation of genes coding for polypeptides of NADH dehydrogenase, ATP synthase, and cytochrome c oxidase. Mitochondrial membrane potential, monitored by JC1 staining, was elevated at p10 and p32, and essentially completely absent at p71. The data show that during chronic exposure of HeLa cells to AZT, a compensatory response was induced at the earlier passages (p5-p37), and by p71 there was widespread mitochondrial morphological damage, severe mtDNA depletion, and a substantial loss of mitochondrial membrane potential.
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PMID:Morphological and molecular course of mitochondrial pathology in cultured human cells exposed long-term to Zidovudine. 1689 29

We mapped 226 unique integration sites in human hepatoma cells following gene transfer with a feline immunodeficiency virus (FIV)-based lentivirus vector. FIV integrated across the entire length of the transcriptional units. Microarray data indicated that FIV integration favored actively transcribed genes. Approximately 21% of FIV integrations within transcriptional units occurred in genes regulated by the LEDGF/p75 transcriptional coactivator. DNA in regions of FIV insertion sites exhibited a "bendable" structure and a pattern of duplex destabilization favoring strand separation. FIV integration preferences are more similar to those of primate lentiviruses and distinct from those of Moloney murine leukemia virus, avian sarcoma leukosis virus, and foamy virus.
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PMID:Integration site choice of a feline immunodeficiency virus vector. 1691 28

Chromosomal integration enables human immunodeficiency virus (HIV) to establish a permanent reservoir that can be therapeutically suppressed but not eradicated. Participation of cellular proteins in this obligate replication step is poorly understood. We used intensified RNA interference and dominant-negative protein approaches to show that the cellular transcriptional coactivator lens epithelium-derived growth factor (LEDGF)/p75 (p75) is an essential HIV integration cofactor. The mechanism requires both linkages of a molecular tether that p75 forms between integrase and chromatin. Fractionally minute levels of endogenous p75 are sufficient to enable integration, showing that cellular factors that engage HIV after entry may elude identification in less intensive knockdowns. Perturbing the p75-integrase interaction may have therapeutic potential.
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PMID:An essential role for LEDGF/p75 in HIV integration. 1695 72

We initially identified lens epithelium-derived growth factor/p75 (LEDGF/p75) as a binding partner of human immunodeficiency virus type 1 (HIV-1) integrase. To investigate the role of LEDGF/p75 in HIV replication and its potential as a new antiviral target, we stably overexpressed two different fragments containing the integrase binding domain (IBD) of LEDGF/p75 fused to enhanced green fluorescent protein (eGFP). HIV-1 replication was severely inhibited by overexpression of the eGFP-IBD fusion proteins, while no inhibition was observed in cell lines overexpressing the interaction-deficient D366A mutant. Quantitative PCR pinpointed the block to the integration step, whereas nuclear import was not affected. Competition of the IBD fusion proteins with endogenous LEDGF/p75 for binding to integrase led to a potent defect in HIV-1 replication in both HeLaP4- and MT-4-derived cell lines. A previously described diketo acid-resistant HIV-1 strain remained fully susceptible to inhibition, suggesting that this strategy will also work in patients who harbor strains resistant to the current experimental integrase inhibitors. These data support LEDGF/p75 as an important cofactor for HIV replication and provide proof of concept for the LEDGF/p75-integrase interaction as a novel target for treating HIV-1 infection.
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PMID:Overexpression of the lens epithelium-derived growth factor/p75 integrase binding domain inhibits human immunodeficiency virus replication. 1698 86

Lens epithelium-derived growth factor (LEDGF)/p75 is an important cellular co-factor for human immunodeficiency virus (HIV) replication. We originally identified LEDGF/p75 as a binding partner of integrase (IN) in human cells. The interaction has been mapped to the integrase-binding domain (IBD) of LEDGF/p75 located in the C-terminal part. We have subsequently shown that IN carrying the Q168A mutation remains enzymatically active but is impaired for interaction with LEDGF/p75. To map the integrase/LEDGF interface in more detail, we have now identified and characterized two regions within the enzyme involved in the interaction with LEDGF/p75. The first region centers around residues W131 and W132 while the second extends from I161 up to E170. For the different IN mutants the interaction with LEDGF/p75 and the enzymatic activities were determined. IN(W131A), IN(I161A), IN(R166A), IN(Q168A) and IN(E170A) are impaired for interaction with LEDGF/p75, but retain 3' processing and strand transfer activities. Due to impaired integration, an HIV-1 strain containing the W131A mutation in IN displays reduced replication capacity, whereas virus carrying IN(Q168A) is replication defective. Comparison of the wild-type IN-LEDGF/p75 co-crystal structure with that of the modelled structure of the IN(Q168A) and IN(W131A) mutant integrases corroborated our experimental data.
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PMID:Identification of the LEDGF/p75 binding site in HIV-1 integrase. 1713 94


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