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https://www.readbyqxmd.com/read/28655787/cytosine-deaminase-apobec3a-sensitizes-leukemia-cells-to-inhibition-of-the-dna-replication-checkpoint
#1
Abby M Green, Konstantin Budagyan, Katharina E Hayer, Morgann A Reed, Milan R Savani, Gerald B Wertheim, Matthew D Weitzman
Mutational signatures in cancer genomes have implicated the APOBEC3 cytosine deaminases in oncogenesis, possibly offering a therapeutic vulnerability. Elevated APOBEC3B expression has been detected in solid tumors, but expression of APOBEC3A (A3A) in cancer has not been described to date. Here we report that A3A is highly expressed in subsets of pediatric and adult acute myeloid leukemia (AML). We modeled A3A expression in the THP1 AML cell line by introducing an inducible A3A gene. A3A expression caused ATR-dependent phosphorylation of Chk1 and cell cycle arrest, consistent with replication checkpoint activation...
June 27, 2017: Cancer Research
https://www.readbyqxmd.com/read/28646470/apobec3b-and-il-6-form-a-positive-feedback-loop-in-hepatocellular-carcinoma-cells
#2
Shuran Li, Xueyang Bao, Duowei Wang, Linjun You, Xianjing Li, Hongbao Yang, Jinsong Bian, Yun Wang, Yong Yang
APOBEC3 protein families, a DNA cytidine deaminase, were up-regulated in multiple tumors. However, the relationship between Hepatocellular carcinoma (HCC) and APOBEC3B (A3B) remains unknown. It has been confirmed that interleukin-6 (IL-6) has significant impacts on oncogenesis of HCC. Here, we reported that the expression of IL-6 was substantially up-regulated by A3B in HepG2 cells. A3B induced IL-6 expression through relocating HuR to enhance the IL-6 mRNA stability. Further analysis indicated that IL-6 also increased the expression of A3B through JAK1/STAT3 signaling pathway, which formed a positive feedback to maintain the continuous expression of A3B and IL-6, and thereby promoted the prolonged non-resolving inflammation...
May 29, 2017: Science China. Life Sciences
https://www.readbyqxmd.com/read/28637869/heat-shock-proteins-stimulate-apobec-3-mediated-cytidine-deamination-in-the-hepatitis-b-virus
#3
Zhigang Chen, Thomas L Eggerman, Alexander V Bocharov, Irina N Baranova, Tatyana G Vishnyakova, Roger Kurlander, Amy P Patterson
Apolipoprotein B mRNA-editing enzyme catalytic subunit 3 (APOBEC-3) enzymes are cytidine deaminases that are broadly and constitutively expressed. They are often upregulated during carcinogenesis and candidate genes for causing the major single-base substitution in cancer-associated DNA mutations. Moreover, APOBEC-3s are involved in host innate immunity against many viruses. However, how APOBEC-3 mutational activity is regulated in normal and pathological conditions remains largely unknown. Heat shock protein levels are often elevated in both carcinogenesis and viral infection and are associated with DNA mutations...
June 21, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28620460/a-putative-antiviral-role-of-plant-cytidine-deaminases
#4
Susana Martín, José M Cuevas, Ana Grande-Pérez, Santiago F Elena
BACKGROUND: A mechanism of innate antiviral immunity operating against viruses infecting mammalian cells has been described during the last decade.  Host cytidine deaminases ( e.g., APOBEC3 proteins) edit viral genomes, giving rise to hypermutated nonfunctional viruses; consequently, viral fitness is reduced through lethal mutagenesis.  By contrast, sub-lethal hypermutagenesis may contribute to virus evolvability by increasing population diversity.  To prevent genome editing, some viruses have evolved proteins that mediate APOBEC3 degradation...
2017: F1000Research
https://www.readbyqxmd.com/read/28604942/micrornas-regulate-apobec-gene-expression
#5
REVIEW
Wei Cao, Wei Wu
Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) is a family of evolutionarily conserved cytidine deaminases, encoded by eleven genes located in the human genome. APOBECs play key roles in innate immunity through their ability to mutagenize viral DNA and restrict rival replication. Recent cancer genomics revealed APOBEC3 subtype-mediated APOBEC-signature mutations are common in a broad spectrum of human cancers. The pervasive APOBEC3 activation in the host genome which converts cytosine to uracile during RNA editing has been suggested to depend on ATR/chk1 pathways...
June 12, 2017: Histology and Histopathology
https://www.readbyqxmd.com/read/28516844/clues-for-two-step-virion-infectivity-factor-regulation-by-core-binding-factor-beta
#6
Youwei Ai, Jianzhang Ma, Xiaojun Wang
Lentiviruses threaten human and animal health. Virion infectivity factor (Vif) is essential for the infectivity of most lentiviruses, except for the equine infectious anaemia virus (EIAV). Vif promotes viral infectivity by recruiting a Cullin-based E3 ligase to induce the degradation of a class of host restriction factors, named APOBEC3. Core binding factor beta (CBF-β) is necessary for several primate lentiviral Vif functions, including HIV-1 Vif. Although much progress has been made in understanding the contribution of CBF-β to Vif function, the precise mechanism has not yet been fully elucidated...
May 2017: Journal of General Virology
https://www.readbyqxmd.com/read/28482907/a-conflict-of-interest-the-evolutionary-arms-race-between-mammalian-apobec3-and-lentiviral-vif
#7
REVIEW
Yusuke Nakano, Hirofumi Aso, Andrew Soper, Eri Yamada, Miyu Moriwaki, Guillermo Juarez-Fernandez, Yoshio Koyanagi, Kei Sato
Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3 (APOBEC3) proteins are mammalian-specific cellular deaminases and have a robust ability to restrain lentivirus replication. To antagonize APOBEC3-mediated antiviral action, lentiviruses have acquired viral infectivity factor (Vif) as an accessory gene. Mammalian APOBEC3 proteins inhibit lentiviral replication by enzymatically inserting G-to-A hypermutations in the viral genome, whereas lentiviral Vif proteins degrade host APOBEC3 via the ubiquitin/proteasome-dependent pathway...
May 8, 2017: Retrovirology
https://www.readbyqxmd.com/read/28475648/hiv-1-competition-experiments-in-humanized-mice-show-that-apobec3h-imposes-selective-pressure-and-promotes-virus-adaptation
#8
Yusuke Nakano, Naoko Misawa, Guillermo Juarez-Fernandez, Miyu Moriwaki, Shinji Nakaoka, Takaaki Funo, Eri Yamada, Andrew Soper, Rokusuke Yoshikawa, Diako Ebrahimi, Yuuya Tachiki, Shingo Iwami, Reuben S Harris, Yoshio Koyanagi, Kei Sato
APOBEC3 (A3) family proteins are DNA cytosine deaminases recognized for contributing to HIV-1 restriction and mutation. Prior studies have demonstrated that A3D, A3F, and A3G enzymes elicit a robust anti-HIV-1 effect in cell cultures and in humanized mouse models. Human A3H is polymorphic and can be categorized into three phenotypes: stable, intermediate, and unstable. However, the anti-viral effect of endogenous A3H in vivo has yet to be examined. Here we utilize a hematopoietic stem cell-transplanted humanized mouse model and demonstrate that stable A3H robustly affects HIV-1 fitness in vivo...
May 5, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28452355/crystal-structure-of-apobec3a-bound-to-single-stranded-dna-reveals-structural-basis-for-cytidine-deamination-and-specificity
#9
Takahide Kouno, Tania V Silvas, Brendan J Hilbert, Shivender M D Shandilya, Markus F Bohn, Brian A Kelch, William E Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A Schiffer
Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive...
April 28, 2017: Nature Communications
https://www.readbyqxmd.com/read/28443724/genetic-diversity-of-hiv-1-gene-vif-among-treatment-naive-brazilians
#10
Fabiola Villanova, Marta Barreiros, Luiz Mário Janini, Ricardo Sobhie Diaz, Élcio Leal
HIV-1 has the Vif protein, which binds to human antiviral proteins APOBEC3 to form complexes to be degraded by cellular proteolysis. To further explore HIV-1 diversity at the population level, we analyzed blood samples from 317 treatment-naive patients in Brazil. In this study, we explored the correlations of Vif polymorphisms with clinical parameters of the patients and found that mutation K22H is associated with low CD4(+) cell counts and higher viral loads. Phylogenetic analysis of the vif gene indicated that subtype B was predominant in ∼77% (243/317) of the patients, followed by HIV-1 F ∼18% (56/317), and subtype C ∼4% (12/317); five samples were BF recombinants (∼1% of patients), and one was an AG recombinant...
May 24, 2017: AIDS Research and Human Retroviruses
https://www.readbyqxmd.com/read/28439266/a-novel-regulator-of-activation-induced-cytidine-deaminase-apobecs-in-immunity-and-cancer-schr%C3%A3-dinger-s-catalytic-pocket
#11
REVIEW
Justin J King, Mani Larijani
Activation-induced cytidine deaminase (AID) and its relative APOBEC3 cytidine deaminases boost immune response by mutating immune or viral genes. Because of their genome-mutating activities, AID/APOBECs are also drivers of tumorigenesis. Due to highly charged surfaces, extensive non-specific protein-protein/nucleic acid interactions, formation of polydisperse oligomers, and general insolubility, structure elucidation of these proteins by X-ray crystallography and NMR has been challenging. Hence, almost all available AID/APOBEC structures are of mutated and/or truncated versions...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28429755/opossum-apobec1-is-a-dna-mutator-with-retrovirus-and-retroelement-restriction-activity
#12
Terumasa Ikeda, Mayuko Shimoda, Diako Ebrahimi, John L VandeBerg, Reuben S Harris, Atsushi Koito, Kazuhiko Maeda
APOBEC3s (A3s) are single-stranded DNA cytosine deaminases that provide innate immune defences against retroviruses and mobile elements. A3s are specific to eutherian mammals because no direct homologs exist at the syntenic genomic locus in metatherian (marsupial) or prototherian (monotreme) mammals. However, the A3s in these species have the likely evolutionary precursors, the antibody gene deaminase AID and the RNA/DNA editing enzyme APOBEC1 (A1). Here, we used cell culture-based assays to determine whether opossum A1 restricts the infectivity of retroviruses including human immunodeficiency virus type 1 (HIV-1) and the mobility of LTR/non-LTR retrotransposons...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28415995/type-i-interferon-signaling-is-required-for-the-apobec3-rfv3-dependent-neutralizing-antibody-response-but-not-innate-retrovirus-restriction
#13
Bradley S Barrett, Michael S Harper, Sean T Jones, Kejun Guo, Karl J Heilman, Ross M Kedl, Kim J Hasenkrug, Mario L Santiago
BACKGROUND: APOBEC3/Rfv3 restricts acute Friend retrovirus (FV) infection and promotes virus-specific neutralizing antibody (NAb) responses. Classical Rfv3 studies utilized FV stocks containing lactate-dehydrogenase elevating virus (LDV), a potent type I interferon inducer. Previously, we showed that APOBEC3 is required for the anti-FV activity of exogenous IFN-alpha treatment. Thus, type I interferon receptor (IFNAR) signaling may be required for the APOBEC3/Rfv3 response. RESULTS: To test if the APOBEC3/Rfv3 response is dependent on type I IFN signaling, we infected IFNAR knockout versus IFNAR/APOBEC3 double-knockout mice with FV/LDV or LDV-free FV, and evaluated acute FV infection and subsequent NAb titers...
April 17, 2017: Retrovirology
https://www.readbyqxmd.com/read/28405512/high-expression-of-pd-1-ligands-is-associated-with-kataegis-mutational-signature-and-apobec3-alterations
#14
Amélie Boichard, Igor F Tsigelny, Razelle Kurzrock
Immunotherapy with checkpoint inhibitors, such as antibodies blocking the programmed cell-death receptor-1 (PD-1), has resulted in remarkable responses in patients having traditionally refractory cancers. Although response to PD-1 inhibitors correlates with PD-1 ligand (PD-L1 or PD-L2) expression, PD-1 ligand positivity represents only a part of the predictive model necessary for selecting patients predisposed to respond to immunotherapy. We used all genomic, transcriptomic, proteomic and phenotypic data related to 8,475 pan-cancer samples available in The Cancer Genome Atlas (TCGA) and conducted a logistic regression analysis based on a large set of variables, such as microsatellite instability (MSI-H), mismatch repair (MMR) alterations, polymerase δ (POLD1) and polymerase ε (POLE) mutations, activation-induced/apolipoprotein-B editing cytidine deaminases (AID/APOBEC) alterations, lymphocyte markers and mutation burden estimates to determine independent factors that associate with PD-1 ligand overexpression...
2017: Oncoimmunology
https://www.readbyqxmd.com/read/28369637/nmr-based-method-of-small-changes-reveals-how-dna-mutator-apobec3a-interacts-with-its-single-stranded-dna-substrate
#15
Stefan Harjes, Geoffrey B Jameson, Vyacheslav V Filichev, Patrick J B Edwards, Elena Harjes
APOBEC3 proteins are double-edged swords. They deaminate cytosine to uracil in single-stranded DNA and provide protection, as part of our innate immune system, against viruses and retrotransposons, but they are also involved in cancer evolution and development of drug resistance. We report a solution-state model of APOBEC3A interaction with its single-stranded DNA substrate obtained with the 'method of small changes'. This method compares pairwise the 2D 15N-1H NMR spectra of APOBEC3A bearing a deactivating mutation E72A in the presence of 36 slightly different DNA substrates...
May 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28336404/mapping-region-of-human-restriction-factor-apobec3h-critical-for-interaction-with-hiv-1-vif
#16
Masaaki Nakashima, Shinya Tsuzuki, Hiroaki Awazu, Akiko Hamano, Ayaka Okada, Hirotaka Ode, Masami Maejima, Atsuko Hachiya, Yoshiyuki Yokomaku, Nobuhisa Watanabe, Hirofumi Akari, Yasumasa Iwatani
The APOBEC3 (A3) family of cellular cytidine deaminases comprises seven members (A, B, C, D, F, G, and H) that potently inhibit retroviral replication. Human immunodeficiency virus type 1 (HIV-1) Vif is a small pleiotropic protein that specifically inactivates these enzymes, targeting them for ubiquitin-mediated proteasomal degradation. A3 Vif-interaction sites are presumed to fall into three distinct types: A3C/D/F, A3G, and A3H. To date, two types of A3G and A3C/D/F sites have been well characterized, whereas the A3H Vif-binding site remains poorly defined...
April 21, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28331087/feline-immunodeficiency-virus-evolutionarily-acquires-two-proteins-vif-and-protease-capable-of-antagonizing-feline-apobec3
#17
Rokusuke Yoshikawa, Junko S Takeuchi, Eri Yamada, Yusuke Nakano, Naoko Misawa, Yuichi Kimura, Fengrong Ren, Takayuki Miyazawa, Yoshio Koyanagi, Kei Sato
The interplay between viral and host proteins has been well studied to elucidate virus-host interactions and their relevance to virulence. Mammalian genes encode apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) proteins, which act as intrinsic restriction factors against lentiviruses. To overcome APOBEC3-mediated antiviral actions, lentiviruses have evolutionarily acquired an accessory protein, viral infectivity factor (Vif), and Vif degrades host APOBEC3 proteins via a ubiquitin/proteasome-dependent pathway...
June 1, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28315663/enhancing-the-catalytic-deamination-activity-of-apobec3c-is-insufficient-to-inhibit-vif-deficient-hiv-1
#18
Ananda Ayyappan Jaguva Vasudevan, Henning Hofmann, Dieter Willbold, Dieter Häussinger, Bernd W Koenig, Carsten Münk
The retroviral restriction factors of the APOBEC3 (A3) cytidine deaminase family catalyze the deamination of cytidines in single-stranded viral DNA. APOBEC3C (A3C) is a strong antiviral factor against viral infectivity factor (vif)-deficient simian immunodeficiency virus Δvif, which is, however, a weak inhibitor against human immunodeficiency virus (HIV)-1 for reasons unknown. The precise link between the antiretroviral effect of A3C and its catalytic activity is incompletely understood. Here, we show that the S61P mutation in human A3C (A3C...
April 21, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28302150/identification-of-a-tripartite-interaction-between-the-n-terminus-of-hiv-1-vif-and-cbf%C3%AE-that-is-critical-for-vif-function
#19
Belete A Desimmie, Jessica L Smith, Hiroshi Matsuo, Wei-Shau Hu, Vinay K Pathak
BACKGROUND: HIV-1 Vif interacts with the cellular core-binding factor β (CBFβ) and counteracts the protective roles of certain human APOBEC3 (A3) proteins by targeting them for proteasomal degradation. Previous studies have identified some amino acids important for Vif-CBFβ interactions, and recently a co-crystal structure of a pentameric complex of HIV-1 Vif, CBFβ, Cul5, EloB, and EloC was resolved. However, a comprehensive analysis of Vif-CBFβ interactions that are important for Vif function has not been performed...
March 17, 2017: Retrovirology
https://www.readbyqxmd.com/read/28299671/cbf%C3%A3-and-hiv-infection
#20
Dong Young Kim, John D Gross
In order to achieve a persistent infection, viruses must overcome the host immune system. Host restriction factors dominantly block virus transmission, but are subject to down regulation by viral accessory proteins. HIV encodes several accessory factors that overcome different cellular restriction factors. For example, the HIV-1 protein Vif down regulates the human APOBEC3 family of restriction factors by targeting them for proteolysis by the ubiquitin-proteasome pathway. Recently, this function was shown to require the transcription cofactor CBFβ, which acts as a template to assist in Vif folding and allow for assembly of an APOBEC3-targeting E3 ligase complex...
2017: Advances in Experimental Medicine and Biology
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