Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lipoatrophy is a selective loss of subcutaneous adipose tissue and a highly prevalent complication of antiretroviral therapy (ART). This form of fat wasting is associated with decreased quality of life, disincentive for adherence to antiretroviral therapy, as well as possibly an increased risk of coronary artery disease. Clinical trials have incriminated long-term ART with nucleoside analogue reverse transcriptase inhibitors (NRTIs) in general and stavudine in particular. The exact mechanism of fat wasting remains unclear, but the pathogenesis can largely be attributed to the mitochondrial toxicity of NRTIs. NRTIs are inhibitors of polymerase gamma, an enzyme which is necessary for the replication of mitochondrial DNA (mtDNA). Indeed, low amounts of mtDNA, abnormalities of mitochondrial ultrastructure, and respiratory chain dysfunction were identified in the subcutaneous fat tissue and skeletal muscle of HIV-patients under ART and linked to the use of stavudine. Switching away from the incriminated NRTI, is of proven benefit, but may not always be feasible. Supplementation with uridine should be investigated in the prevention and treatment of lipoatrophy based on its potential to competitively attenuate the mtDNA decline caused by pyrimidine NRTIs.
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PMID:Role of mitochondria in HIV lipoatrophy: insight into pathogenesis and potential therapies. 1612 Mar 76

Long-term side effects of antiretroviral therapy are attributed to the mitochondrial (mt) toxicity of nucleoside analogue reverse transcriptase inhibitors (NRTIs) and their ability to deplete mtDNA. Studies in hepatocytes suggest that uridine is able to prevent and treat mtDNA depletion by pyrimidine NRTls [zalcitabine (ddC) and stavudine (d4T)] and to fully abrogate hepatocyte death, elevated lactate production and intracellular steatosis. Uridine was also found to improve the liver and haematopoietic toxicities of zidovudine (AZT), which are unrelated to mtDNA depletion, and to prevent neuronal cell death induced by ddC. Most recently, uridine was found to prevent the onset of a lipoatrophic phenotype (reduced intracellular lipids, increased apoptosis, mtDNA depletion and mt depolarization) in adipocytes incubated long-term with d4T and AZT. Various steps of mt nucleoside utilization may be involved in the protective effect, but competition of uridine metabolites with NRTIs at polymerase y or other enzymes is a plausible explanation. Pharmacokinetic studies suggest that uridine serum levels can be safely increased in humans to achieve concentrations which are protective in vitro (50-200 microM). Uridine was not found to interfere with the antiretroviral activity of NRTIs. Mitocnol, a sugar cane extract which effectively increases uridine in human serum, was beneficial in individual HIV patients with mt toxicity and is now being tested in placebo-controlled randomized trials. Until these data become available, the risk-benefit calculation of using uridine should be individualized. The current safety data justify the closely monitored use of uridine in individuals who suffer from mt toxicity but who cannot be switched to less toxic NRTIs.
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PMID:Uridine in the prevention and treatment of NRTI-related mitochondrial toxicity. 1615 13

Various D- and L-thietanose nucleosides were synthesized from D- and L-xylose. The four-membered thietane ring was efficiently synthesized by the cyclization of 1-thioacetyl-3-mesylate (4/38) under basic conditions. Condensation with various heterocyclic bases was conducted via Pummerer-type rearrangement to afford various nucleoside derivatives. Among the synthesized nucleosides, D-uridine (23), D-cytidine (24), D-5-fluorocytidine (25), and L-cytidine (52) analogues showed moderate anti-HIV activity, with EC50 = 6.9, 1.3, 5.8, and 14.1 microM, respectively. However, these four nucleoside analogues are cytotoxic in peripheral blood mononuclear and CEM cells. The other nucleosides are neither active nor cytotoxic. Interestingly, the oxetanocin A analogue 33 was not active. Comparison of the minimized reverse transcriptases (RTs) complexed with the corresponding triphosphates of the cytidine analogue 24 and the adenosine analogue 33 by molecular modeling studies showed that there is no difference in the binding mode of the triphosphate of the cytidine analogue 24 to the active site of HIV-1 RT from that of the triphosphate of the adenosine analogue 33. Modeling studies on the initial monophosphorylation step by deoxycytidine kinase showed that the catalytic efficiency of phosphorylation through a nucleophilic attack of the 4'-hydroxyl group of thietanose on the gamma-phosphate of ATP is diminished in the case of L-cytidine analogue (52) due to the increased distance between the 4'-hydroxyl group and the gamma-phosphate.
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PMID:Synthesis and anti-HIV activity of D- and L-thietanose nucleosides. 1650 80

APOBEC3G is a potent antiretroviral factor, which belongs to the APOBEC superfamily of cytidine deaminases. It deaminates cytidine to uridine in nascent minus-strand viral DNA, inducing G-to-A hypermutation in the plus-strand viral DNA. HIV-1 Vif protein overcomes the antiviral activity of APOBEC3G by targeting it for ubiquitin-dependent degradation. Recent accumulating evidences that other members of APOBEC proteins also show antiviral activity on a wide variety of viruses suggest that APOBEC family proteins play a crucial role in an antiviral defense as an innate immunity. Here, we review recent progress in research on APOBEC3 proteins.
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PMID:[Antiviral defense by APOBEC3 family proteins]. 1655 12

APOBEC3G has been identified as an anti-human immunodeficiency virus type 1 (HIV-1) host factor that belongs to the APOBEC superfamily of cytidine deaminases. It deaminates cytidine to uridine in nascent minus-strand viral DNA, inducing G-to-A hypermutation in the plus-strand DNA of HIV-1. The accumulating evidence demonstrates that APOBEC family proteins also have an antiviral activity against a wide variety of viruses, including not only retroviruses but also other types of viruses, and that each virus seems to have its own strategy for escaping from APOBEC proteins. These results suggest that the APOBEC3 family plays an important role in antiviral host defense as an innate immunity. Recent progress in research on APOBEC family proteins is reviewed.
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PMID:APOBEC family proteins: novel antiviral innate immunity. 1672 May 50

PA-457 [3-O-(3',3'-dimethylsuccinyl)-betulinic acid] represents a new class of anti-HIV drug candidates termed maturation inhibitors. After oral administration to rats, PA-457 was metabolized to several glucuronide conjugates and mainly eliminated into rat bile. Liquid chromatography-electrospray ionization-mass spectrometry analysis showed that the glucuronidation products of PA-457 were acyl glucuronides including one di-glucuronide, di-PA-457G, and two mono-glucuronides, referred to as mono-PA-457G (I) and mono-PA-457G (II), respectively. In-source fragmentation of MS spectra supported the conclusion that mono-PA-457G (I) was glucuronidated at the C-28 carboxyl of PA-457, whereas mono-PA-457G (II) was conjugated at the dimethylsuccinic acid side chain of the C-3 position. Quantification demonstrated that the predominant glucuronide of PA-457 in rat bile was mono-PA-457G (I) with lower amounts of mono-PA-457G (II) and di-PA-457G. In vitro stability indicated that the mono-acyl glucuronides of PA-457 were not degraded after incubation with 0.1 M phosphate buffer (pH 4, 7.4 and 9), plasma (human, rat, and mouse), and UDP-glucuronosyltransferase reaction media (without uridine 5'-diphosphoglucuronic acid) with microsomes (human, rat, and mouse liver microsomes), respectively, whereas the minor diglucuronide was unstable in rodent liver microsomes. All glucuronides of PA-457 could be hydrolyzed both by beta-glucuronidase and alkaline (1 M NaOH). Minor putative acyl migration products were slowly formed at pH 9, suggesting that the acyl glucuronides of PA-457 have relatively high in vitro stability.
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PMID:Structural characterization of anti-HIV drug candidate PA-457 [3-O-(3',3'-dimethylsuccinyl)-betulinic acid] and its acyl glucuronides in rat bile and evaluation of in vitro stability in human and animal liver microsomes and plasma. 1675 Dec 62

Supplementation with uridine offers the possibility of a new and promising approach to nucleoside analogue reverse transcriptase inhibitor-associated mitochondrial toxicity. We investigated the metabolic effects of short-course treatment with the uridine-enriched food supplement NucleomaxX on hepatic mitochondrial function in thymidine-analogue treated HIV-infected patients. Mitochondrial function was assessed by a recently introduced non-invasive C-methionine breath test. NucleomaxX supplementation enhanced mitochondrial decarboxylation function reversibly but reproducibly in all patients. Repeated administration in shorter treatment intervals may maintain this effect.
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PMID:Uridine supplementation enhances hepatic mitochondrial function in thymidine-analogue treated HIV-infected patients. 1684 12

Members of the APOBEC family of cellular polynucleotide cytidine deaminases (e.g., APOBEC3G) are potent inhibitors of HIV infection. Wild type viral infections are largely spared from APOBEC function through the action of the viral Vif protein. In Vif's absence, inhibitory APOBEC proteins are encapsidated by budding virus particles leading to excessive cytidine (C) to uridine (U) hypermutation of negative sense reverse transcripts in newly infected cells. This registers as guanosine (G) to adenosine (A) mutations in plus stranded cDNA. Because the functions of Vif and APOBEC proteins oppose each other, it is likely that fluctuations in the Vif/APOBEC balance can influence the natural history of HIV infection. Experimental support for this notion would further justify and stimulate drug discovery initiatives in this area.
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PMID:Natural resistance to HIV infection: The Vif-APOBEC interaction. 1706 30

Apolipoprotein B mRNA-editing, enzyme-catalytic, polypeptide-like-3G (A3G) is an intracellular innate antiviral factor that deaminates retroviral cytidine to uridine. In an attempt to harness the anti-HIV effect of A3G, we searched for an agent that would up-regulate A3G and identify the receptors involved. Stimulation of cell surface CCR5 with CCL3 and CD40 with CD40L or both molecules with microbial 70-kDa heat shock protein (HSP)70 up-regulated A3G mRNA and protein expression in human CD4(+) T cells and monocyte-derived dendritic cells (DC), demonstrated by real-time PCR and Western blots, respectively. The specificity of CCR5 and CD40 stimulation was established by inhibition with TAK 779 and mAb to CD40, as well as using human embryonic kidney 293 cells transfected with CCR5 and CD40, respectively. A dose-dependent increase of A3G in CCL3- or HSP70-stimulated CD4(+) T cells was associated with inhibition in HIV-1 infectivity. To differentiate between the inhibitory effect of HSP70-induced CCR5 binding and that of A3G, GFP-labeled pseudovirions were used to infect human embryonic kidney 293 cells, which showed inhibition of pseudovirion uptake, consistent with A3G being responsible for the inhibitory effect. Ligation of cell surface CCR5 receptors by CCL3 or CD40 by CD40L activated the ERK1/2 and p38 MAPK signaling pathways that induced A3G mRNA expression and production of the A3G protein. These in vitro results were corroborated by in vivo studies in rhesus macaques in which A3G was significantly up-regulated following immunization with SIVgp120 and p27 linked to HSP70. This novel preventive approach may in addition to adaptive immunity use the intracellular innate antiviral effect of A3G.
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PMID:Stimulation of cell surface CCR5 and CD40 molecules by their ligands or by HSP70 up-regulates APOBEC3G expression in CD4(+) T cells and dendritic cells. 1723 17

Immune activation is a major characteristic of human immunodeficiency virus type 1 (HIV-1) infection and a strong prognostic factor for HIV-1 disease progression. The underlying mechanisms leading to immune activation in viremic HIV-1 infection, however, are not fully understood. Here we show that, following the initiation of highly active antiretroviral therapy, the immediate decline of immune activation is closely associated with the reduction of HIV-1 viremia, which suggests a direct contribution of HIV-1 itself to immune activation. To propose a mechanism, we demonstrate that the single-stranded RNA of HIV-1 encodes multiple uridine-rich Toll-like receptor 7/8 (TLR7/8) ligands that induce strong MyD88-dependent plasmacytoid dendritic cell and monocyte activation, as well as accessory cell-dependent T-cell activation. HIV-1-encoded TLR ligands may, therefore, directly contribute to the immune activation observed during viremic HIV-1 infection. These data provide an initial rationale for inhibiting the TLR pathway to directly reduce the chronic immune activation induced by HIV-1 and the associated immune pathogenesis.
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PMID:MyD88-dependent immune activation mediated by human immunodeficiency virus type 1-encoded Toll-like receptor ligands. 1750 80


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