RESUMO
INTRODUCTION: Human immunodeficiency virus (HIV) / hepatitis B virus (HBV) causes higher rates of liver disease compared to infection with just one virus. Co-infection can accelerate the progression to liver fibrosis or hepatocellular carcinoma and disturb the treatment response. APOBEC3G is a host defense factor which interferes with HIV-1 and HBV. We aimed to determine the prevalence of hepatitis B surface antigen (HBsAg) among HIV-infected patients and seronegative controls, and screen the HIV/HBV population for APOBEC3G variants rs8177832, rs35228531 and rs2294367, previously associated with HIV-1 infection susceptibility in Morocco. METHODOLOGY: A case control study was conducted on 404 individuals (204 HIV-infected and 200 eligible blood donors) from April to November 2021. HBsAg was measured on the Roche Cobas e411 automatic analyzer (Roche Diagnostics, Basel, Switzerland) and APOBEC3G polymorphisms were identified using the TaqMan genotyping allelic discrimination method. Fisher Exact test, odds ratio (OR) with 95% confidence interval (CI), and haplotype frequencies were calculated. RESULTS: Of the 204 HIV-1 seropositive patients and 200 controls, 4.9% (95%CI: 2.38-8.83) and 2.50% (95% CI: 0.82-5.74) were HBsAg-positive respectively. There was a significant association between increasing age (> 40 years) and HBV infection among controls (p = 0.04). The distribution of genotypes and alleles frequencies of APOBEC3G variants was heterogenous and five different haplotypes with frequencies ≥ 5% were obtained, of which ACC (rs8177832, rs35228531, rs2294367) was the most prevalent. CONCLUSIONS: HBV co-infection is common among HIV-1 infected individuals in Morocco. Efforts should be made to prevent, treat and control HBV transmission in this population.
Assuntos
Desaminase APOBEC-3G , Coinfecção , Infecções por HIV , Antígenos de Superfície da Hepatite B , Humanos , Marrocos/epidemiologia , Masculino , Infecções por HIV/genética , Infecções por HIV/complicações , Infecções por HIV/epidemiologia , Feminino , Adulto , Coinfecção/genética , Coinfecção/epidemiologia , Coinfecção/virologia , Desaminase APOBEC-3G/genética , Estudos de Casos e Controles , Antígenos de Superfície da Hepatite B/genética , Antígenos de Superfície da Hepatite B/sangue , Pessoa de Meia-Idade , Prevalência , Hepatite B/genética , Hepatite B/epidemiologia , Hepatite B/complicações , HIV-1/genética , Adulto Jovem , Vírus da Hepatite B/genéticaRESUMO
Intra-organism biodiversity is thought to arise from epigenetic modification of constituent genes and post-translational modifications of translated proteins. Here, we show that post-transcriptional modifications, like RNA editing, may also contribute. RNA editing enzymes APOBEC3A and APOBEC3G catalyze the deamination of cytosine to uracil. RNAsee (RNA site editing evaluation) is a computational tool developed to predict the cytosines edited by these enzymes. We find that 4.5% of non-synonymous DNA single nucleotide polymorphisms that result in cytosine to uracil changes in RNA are probable sites for APOBEC3A/G RNA editing; the variant proteins created by such polymorphisms may also result from transient RNA editing. These polymorphisms are associated with over 20% of Medical Subject Headings across ten categories of disease, including nutritional and metabolic, neoplastic, cardiovascular, and nervous system diseases. Because RNA editing is transient and not organism-wide, future work is necessary to confirm the extent and effects of such editing in humans.
Assuntos
Desaminases APOBEC , Citidina Desaminase , Edição de RNA , Humanos , Citidina Desaminase/metabolismo , Citidina Desaminase/genética , Polimorfismo de Nucleotídeo Único , Citosina/metabolismo , Desaminase APOBEC-3G/metabolismo , Desaminase APOBEC-3G/genética , Uracila/metabolismo , Proteínas/genética , Proteínas/metabolismo , Citosina Desaminase/genética , Citosina Desaminase/metabolismoRESUMO
APOBEC3G (A3G) restricts HIV-1 replication primarily by reducing viral cDNA and inducing G-to-A hypermutations in viral cDNA. HIV-1 encodes virion infectivity factor (Vif) to counteract A3G primarily by excluding A3G viral encapsidation. Even though the Vif-induced exclusion is robust, studies suggest that A3G is still detectable in the virion. The impact of encapsidated A3G in the HIV-1 replication is unclear. Using a highly sensitive next-generation sequencing (NGS)-based G-to-A hypermutation detecting assay, we found that wild-type HIV-1 produced from A3G-expressing T-cells induced higher G-to-A hypermutation frequency in viral cDNA than HIV-1 from non-A3G-expressing T-cells. Interestingly, although the virus produced from A3G-expressing T-cells induced higher hypermutation frequency, there was no significant difference in viral infectivity, revealing a disassociation of cDNA G-to-A hypermutation to viral infectivity. We also measured G-to-A hypermutation in the viral RNA genome. Surprisingly, our data showed that hypermutation frequency in the viral RNA genome was significantly lower than in the integrated DNA, suggesting a mechanism exists to preferentially select intact genomic RNA for viral packing. This study revealed a new insight into the mechanism of HIV-1 counteracting A3G antiviral function and might lay a foundation for new antiviral strategies.
Assuntos
Desaminase APOBEC-3G , DNA Complementar , HIV-1 , Mutação , Humanos , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , DNA Complementar/genética , DNA Viral/genética , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Infecções por HIV/virologia , HIV-1/genética , HIV-1/patogenicidade , Linfócitos T/virologia , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , Replicação Viral/genéticaRESUMO
Human retroviruses are derived from simian ones through cross-species transmission. These retroviruses are associated with little pathogenicity in their natural hosts, but in humans, HIV causes AIDS, and human T-cell leukemia virus type 1 (HTLV-1) induces adult T-cell leukemia-lymphoma (ATL). We analyzed the proviral sequences of HTLV-1, HTLV-2, and simian T-cell leukemia virus type 1 (STLV-1) from Japanese macaques (Macaca fuscata) and found that APOBEC3G (A3G) frequently generates G-to-A mutations in the HTLV-1 provirus, whereas such mutations are rare in the HTLV-2 and STLV-1 proviruses. Therefore, we investigated the mechanism of how HTLV-2 is resistant to human A3G (hA3G). HTLV-1, HTLV-2, and STLV-1 encode the so-called antisense proteins, HTLV-1 bZIP factor (HBZ), Antisense protein of HTLV-2 (APH-2), and STLV-1 bZIP factor (SBZ), respectively. APH-2 efficiently inhibits the deaminase activity of both hA3G and simian A3G (sA3G). HBZ and SBZ strongly suppress sA3G activity but only weakly inhibit hA3G, suggesting that HTLV-1 is incompletely adapted to humans. Unexpectedly, hA3G augments the activation of the transforming growth factor (TGF)-ß/Smad pathway by HBZ, and this activation is associated with ATL cell proliferation by up-regulating BATF3/IRF4 and MYC. In contrast, the combination of APH-2 and hA3G, or the combination of SBZ and sA3G, does not enhance the TGF-ß/Smad pathway. Thus, HTLV-1 is vulnerable to hA3G but utilizes it to promote the proliferation of infected cells via the activation of the TGF-ß/Smad pathway. Antisense factors in each virus, differently adapted to control host cellular functions through A3G, seem to dictate the pathogenesis.
Assuntos
Vírus Linfotrópico T Tipo 1 Humano , Leucemia-Linfoma de Células T do Adulto , Humanos , Linhagem Celular , Virulência , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Leucemia-Linfoma de Células T do Adulto/genética , Provírus/genética , Fator de Crescimento Transformador beta/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Desaminase APOBEC-3G/genéticaRESUMO
Human APOBEC3 enzymes are a family of single-stranded (ss)DNA and RNA cytidine deaminases that act as part of the intrinsic immunity against viruses and retroelements. These enzymes deaminate cytosine to form uracil which can functionally inactivate or cause degradation of viral or retroelement genomes. In addition, APOBEC3s have deamination-independent antiviral activity through protein and nucleic acid interactions. If expression levels are misregulated, some APOBEC3 enzymes can access the human genome leading to deamination and mutagenesis, contributing to cancer initiation and evolution. While APOBEC3 enzymes are known to interact with large ribonucleoprotein complexes, the function and RNA dependence are not entirely understood. To further understand their cellular roles, we determined by affinity purification mass spectrometry (AP-MS) the protein interaction network for the human APOBEC3 enzymes and mapped a diverse set of protein-protein and protein-RNA mediated interactions. Our analysis identified novel RNA-mediated interactions between APOBEC3C, APOBEC3H Haplotype I and II, and APOBEC3G with spliceosome proteins, and APOBEC3G and APOBEC3H Haplotype I with proteins involved in tRNA methylation and ncRNA export from the nucleus. In addition, we identified RNA-independent protein-protein interactions with APOBEC3B, APOBEC3D, and APOBEC3F and the prefoldin family of protein-folding chaperones. Interaction between prefoldin 5 (PFD5) and APOBEC3B disrupted the ability of PFD5 to induce degradation of the oncogene cMyc, implicating the APOBEC3B protein interaction network in cancer. Altogether, the results uncover novel functions and interactions of the APOBEC3 family and suggest they may have fundamental roles in cellular RNA biology, their protein-protein interactions are not redundant, and there are protein-protein interactions with tumor suppressors, suggesting a role in cancer biology. Data are available via ProteomeXchange with the identifier PXD044275.
Assuntos
Citidina Desaminase , Mapas de Interação de Proteínas , Humanos , Citidina Desaminase/metabolismo , Citidina Desaminase/genética , Desaminação , Desaminases APOBEC/metabolismo , Aminoidrolases/metabolismo , Aminoidrolases/genética , Células HEK293 , Citosina Desaminase/metabolismo , Desaminase APOBEC-3G/metabolismo , Desaminase APOBEC-3G/genética , Spliceossomos/metabolismo , Ligação Proteica , Espectrometria de Massas , RNA/metabolismo , Antígenos de Histocompatibilidade Menor/metabolismo , Antígenos de Histocompatibilidade Menor/genéticaRESUMO
PURPOSE: Despite extensive research, HIV-1 remains a global epidemic with variations in pathogenesis across regions and subtypes. The Viral Infectivity Factor (Vif) protein, which neutralizes the host protein APOBEC3G, has been implicated in differences in clinical outcomes among people living with HIV (PLHIV). Most studies on Vif sequence diversity have focused on subtype B, leaving gaps in understanding Vif variations in HIV-1C regions like South Africa. This study aimed to identify and compare Vif sequence diversity in a cohort of 51 South African PLHIV and other HIV-1C prevalent regions. METHODS: Sanger sequencing was used for Vif analysis in the cohort, and additional sequences were obtained from the Los Alamos database. Molecular modeling and docking techniques were employed to study the influence of subtype-specific variants on Vif-APOBEC3G binding affinity. RESULTS: The findings showed distinct genetic variations between Vif sequences from India and Uganda, while South African sequences had wider distribution and closer relatedness to both. Specific amino acid substitutions in Vif were associated with geographic groups. Molecular modeling and docking analyses consistently identified specific residues (ARGR19, LYS26, TYR30, TYR44, and TRP79) as primary contributors to intermolecular contacts between Vif and APOBEC3G, essential for their interaction. The Indian Vif variant exhibited the highest predicted binding affinity to APOBEC3G among the studied groups. CONCLUSIONS: These results provide insights into Vif sequence diversity in HIV-1C prevalent regions and shed light on differential pathogenesis observed in different geographical areas. The identified Vif amino acid residues warrant further investigation for their diagnostic, prognostic, and therapeutic potential.
Assuntos
Infecções por HIV , HIV-1 , Humanos , HIV-1/genética , HIV-1/metabolismo , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , População Africana , Desaminase APOBEC-3G/genéticaRESUMO
HSP40/DNAJ family of proteins is the most diverse chaperone family, comprising about 49 isoforms in humans. Several reports have demonstrated the functional role of a few of these isoforms in the pathogenesis of various viruses, including HIV-1. Our earlier study has shown that several isoforms of HSP40 get significantly modulated at the mRNA level during HIV-1 infection in T cells. To explore the biological role of these significantly modulated isoforms, we analyzed their effect on HIV-1 gene expression and virus production using knockdown and overexpression studies. Among these isoforms, DNAJA3, DNAJB1, DNAJB7, DNAJC4, DNAJC5B, DNAJC5G, DNAJC6, DNAJC22, and DNAJC30 seem to positively regulate virus replication, whereas DNAJB3, DNAJB6, DNAJB8, and DNAJC5 negatively regulate virus replication. Further investigation on the infectivity of the progeny virion demonstrated that only DNAJB8 negatively regulates the progeny virion infectivity. It was further identified that DNAJB8 protein is involved in the downregulation of Vif protein, required for the infectivity of HIV-1 virions. DNAJB8 seems to direct Vif protein for autophagic-lysosomal degradation, leading to rescue of the cellular restriction factor APOBEC3G from Vif-mediated proteasomal degradation, resulting in enhanced packaging of APOBEC3G in budding virions and release of less infective progeny virion particles. Finally, our results also indicate that during the early stage of HIV-1 infection, enhanced expression of DNAJB8 promotes the production of less infective progeny virions, but at the later stage or at the peak of infection, reduced expression of DNJAB8 protein allows the HIV-1 to replicate and produce more infective progeny virion particles.
Assuntos
Infecções por HIV , HIV-1 , Humanos , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , HIV-1/metabolismo , Proteínas Virais/metabolismo , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Produtos do Gene vif/metabolismo , Replicação Viral/fisiologia , Vírion/metabolismo , Infecções por HIV/metabolismo , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/metabolismo , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Proteínas do Tecido Nervoso/metabolismoRESUMO
The APOBEC cytidine deaminase enzyme family is linked to mutational signatures identified in cancer. While previous work has provided insights into the role of APOBEC3A and APOBEC3B in mutational processes in cancer, understanding of the mutational signatures induced by other APOBEC family members is limited. In this issue of Cancer Research, Liu and colleagues investigated the role of APOBEC3G (A3G) in bladder cancer. The authors revealed that transgenic expression of A3G in a murine bladder cancer model promotes tumorigenesis and induces a unique mutational signature distinct from previously identified APOBEC signatures. Expression of this A3G-related mutational signature correlated with significantly worse survival in patients with urothelial bladder carcinoma, and A3G expression was identified in 21 different cancer types. These findings suggest that different APOBEC3 enzymes induce unique mutation signatures and play distinct roles in cancer evolution. More complete understanding of the function of each APOBEC3 enzyme will improve anticancer therapy. See related article by Liu et al., p. 506.
Assuntos
Mutagênicos , Neoplasias da Bexiga Urinária , Humanos , Animais , Camundongos , Mutagênese , Citidina Desaminase/genética , Neoplasias da Bexiga Urinária/genética , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Evolução Clonal , Antígenos de Histocompatibilidade Menor/genéticaRESUMO
Human APOBEC3G (A3G) is a virus restriction factor that inhibits HIV-1 replication and triggers lethal hypermutation on viral reverse transcripts. HIV-1 viral infectivity factor (Vif) breaches this host A3G immunity by hijacking a cellular E3 ubiquitin ligase complex to target A3G for ubiquitination and degradation. The molecular mechanism of A3G targeting by Vif-E3 ligase is unknown, limiting the antiviral efforts targeting this host-pathogen interaction crucial for HIV-1 infection. Here, we report the cryo-electron microscopy structures of A3G bound to HIV-1 Vif in complex with T cell transcription cofactor CBF-ß and multiple components of the Cullin-5 RING E3 ubiquitin ligase. The structures reveal unexpected RNA-mediated interactions of Vif with A3G primarily through A3G's noncatalytic domain, while A3G's catalytic domain is poised for ubiquitin transfer. These structures elucidate the molecular mechanism by which HIV-1 Vif hijacks the host ubiquitin ligase to specifically target A3G to establish infection and offer structural information for the rational development of antiretroviral therapeutics.
Assuntos
Infecções por HIV , HIV-1 , Humanos , Ubiquitina-Proteína Ligases/metabolismo , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , HIV-1/metabolismo , Proteínas Culina/genética , Proteínas Culina/metabolismo , Microscopia Crioeletrônica , Ubiquitina/metabolismo , Ligação Proteica , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismoRESUMO
Mutagenic processes leave distinct signatures in cancer genomes. The mutational signatures attributed to APOBEC3 cytidine deaminases are pervasive in human cancers. However, data linking individual APOBEC3 proteins to cancer mutagenesis in vivo are limited. Here, we showed that transgenic expression of human APOBEC3G promotes mutagenesis, genomic instability, and kataegis, leading to shorter survival in a murine bladder cancer model. Acting as mutagenic fuel, APOBEC3G increased the clonal diversity of bladder cancer, driving divergent cancer evolution. Characterization of the single-base substitution signature induced by APOBEC3G in vivo established the induction of a mutational signature distinct from those caused by APOBEC3A and APOBEC3B. Analysis of thousands of human cancers revealed the contribution of APOBEC3G to the mutational profiles of multiple cancer types, including bladder cancer. Overall, this study dissects the mutagenic impact of APOBEC3G on the bladder cancer genome, identifying that it contributes to genomic instability, tumor mutational burden, copy-number loss events, and clonal diversity. SIGNIFICANCE: APOBEC3G plays a role in cancer mutagenesis and clonal heterogeneity, which can potentially inform future therapeutic efforts that restrict tumor evolution. See related commentary by Caswell and Swanton, p. 487.
Assuntos
Desaminase APOBEC-3G , Evolução Clonal , Mutagênese , Neoplasias da Bexiga Urinária , Animais , Humanos , Camundongos , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Evolução Clonal/genética , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Instabilidade Genômica , Antígenos de Histocompatibilidade Menor/genética , Mutagênese/genética , Mutagênicos , Neoplasias da Bexiga Urinária/genéticaRESUMO
Cytosine deaminases AID/APOBEC proteins act as potent nucleic acid editors, playing important roles in innate and adaptive immunity. However, the mutagenic effects of some of these proteins compromise genomic integrity and may promote tumorigenesis. Here, we demonstrate that human APOBEC3G (A3G), in addition to its role in innate immunity, promotes repair of double-strand breaks (DSBs) in vitro and in vivo. Transgenic mice expressing A3G successfully survived lethal irradiation, whereas wild-type controls quickly succumbed to radiation syndrome. Mass spectrometric analyses identified the differential upregulation of a plethora of proteins involved in DSB repair pathways in A3G-expressing cells early following irradiation to facilitate repair. Importantly, we find that A3G not only accelerates DSB repair but also promotes deamination-dependent error-free rejoining. These findings have two implications: (a) strategies aimed at inhibiting A3G may improve the efficacy of genotoxic therapies used to cure malignant tumours; and (b) enhancing A3G activity may reduce acute radiation syndrome in individuals exposed to ionizing radiation.
Assuntos
Carcinogênese , Imunidade Inata , Humanos , Camundongos , Animais , Linhagem Celular , Mutagênese , Carcinogênese/genética , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Citidina Desaminase/genéticaRESUMO
BACKGROUND: Ubiquitination plays an essential role in many biological processes, including viral infection, and can be reversed by deubiquitinating enzymes (DUBs). Although some studies discovered that DUBs inhibit or enhance viral infection by various mechanisms, there is lack of information on the role of DUBs in virus regulation, which needs to be further investigated. METHODS: Immunoblotting, real-time polymerase chain reaction, in vivo / in vitro deubiquitination, protein immunoprecipitation, immunofluorescence, and co-localization biological techniques were employed to examine the effect of ubiquitin-specific protease 3 (USP3) on APOBEC3G (A3G) stability and human immunodeficiency virus (HIV) replication. To analyse the relationship between USP3 and HIV disease progression, we recruited 20 HIV-infected patients to detect the levels of USP3 and A3G in peripheral blood and analysed their correlation with CD4 + T-cell counts. Correlation was estimated by Pearson correlation coefficients (for parametric data). RESULTS: The results demonstrated that USP3 specifically inhibits HIV-1 replication in an A3G-dependent manner. Further investigation found that USP3 stabilized 90% to 95% of A3G expression by deubiquitinating Vif-mediated polyubiquitination and blocking its degradation in an enzyme-dependent manner. It also enhances the A3G messenger RNA (mRNA) level by binding to A3G mRNA and stabilizing it in an enzyme-independent manner. Moreover, USP3 expression was positively correlated with A3G expression ( r â=â0.5110) and CD4 + T-cell counts ( r â=â0.5083) in HIV-1-infected patients. CONCLUSIONS: USP3 restricts HIV-1 viral infections by increasing the expression of the antiviral factor A3G. Therefore, USP3 may be an important target for drug development and serve as a novel therapeutic strategy against viral infections.
Assuntos
Infecções por HIV , HIV-1 , Humanos , Replicação Viral , Proteases Específicas de Ubiquitina/genética , Proteases Específicas de Ubiquitina/metabolismo , Proteases Específicas de Ubiquitina/farmacologia , Enzimas Desubiquitinantes/metabolismo , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Desaminase APOBEC-3G/farmacologia , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Citidina Desaminase/farmacologiaRESUMO
OBJECTIVES: As a host restriction factor, apolipoprotein B messenger RNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G or A3G) has been shown to suppress the replication of several viruses including hepatitis B virus (HBV). Recently, we reported that IMB-Z, a N-phenylbenzamide derivative, could inhibit Enterovirus 71 replication, and A3G mediated its antiviral activity. Whether IMB-Z exhibits an inhibitory effect on HBV replication has not been investigated. MATERIAL AND METHODS: HBV DNA, pregenomic RNA (pgRNA), core protein, and capsid levels were determined by a qPCR assay or Southern blot, Northern blot, Western blot, and particle gel assay, respectively. Mutation analysis of HBV DNAs was conducted by a differential DNA denaturation PCR assay. A3G encapsidation into HBV nucleocapsids was examined by Western blot analysis after ultracentrifugation and a co-immunoprecipitation (IP) assay between HBV core and A3G proteins. RESULTS: In the present study, we found that IMB-Z could considerably inhibit HBV replication in HepAD38 cells. Interestingly, IMB-Z did not alter the HBV pgRNA production but could reduce the level of core protein, viral nucleocapsids, and core-associated DNA, as well as cccDNA intracellular amplification. Similar to the action of IMB-Z's inhibition of Enterovirus 71 replication, we found that IMB-Z's inhibition of HBV replication was associated with increased level of A3G. Mechanistically, we demonstrated that the inhibitory effect of IMB-Z is independent of the cytidine deaminase activity of A3G and is exerted by increasing its incorporation into viral nucleocapsids. CONCLUSIONS: Our results indicate that IMB-Z inhibits HBV through pharmacological induction A3G expression and incorporation into HBV nucleocapsids.
Assuntos
Desaminase APOBEC-3G , Antivirais , Vírus da Hepatite B , Hepatite B , Humanos , Antivirais/química , Antivirais/farmacologia , Desaminase APOBEC-3G/efeitos dos fármacos , Desaminase APOBEC-3G/genética , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Citidina Desaminase/farmacologia , Hepatite B/tratamento farmacológico , Vírus da Hepatite B/genética , Nucleocapsídeo/genética , Nucleocapsídeo/metabolismo , Replicação ViralRESUMO
The apolipoprotein B mRNA editing enzyme catalytic subunit 3G (APOBEC3G) converts cytosine to uracil in DNA/RNA. Its role in resisting viral invasion has been well documented. However, its expression pattern and potential function in AML remain unclear. In this study, we carried out a bioinformatics analysis and revealed that the expression of APOBEC3G was significantly upregulated in AML, and high expression of APOBEC3G was significantly associated with short overall survival (OS). APOBEC3G expression was especially increased in non-M3AML, and correlated with the unfavorable cytogenetic risks. Additionally, Cox regression analyses indicated APOBEC3G is a hazard factor that cannot be ignored for OS of AML patients. In molecular docking simulations, the natural product crotonoside was found to interact well with APOBEC3G. The expression of APOBEC3G is the highest in KG-1 cells, and the treatment with crotonoside can reduce the expression of APOBEC3G. Crotonoside can inhibit the viability of different AML cells in vitro, arrest KG-1 and MV-4-11 cells in the S phase of the cell cycle and affect the expression of cycle-related proteins, and induce cell apoptosis. Therefore, APOBEC3G could be a potential drug target of crotonoside, and crotonoside can be considered as a lead compound for APOBEC3G inhibition in non-M3 AML.
Assuntos
Produtos Biológicos , HIV-1 , Leucemia Mieloide Aguda , Desaminase APOBEC-1 , Desaminase APOBEC-3G/genética , Adenosina , Biomarcadores , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Citosina , Guanosina , HIV-1/genética , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Simulação de Acoplamento Molecular , Prognóstico , RNA , UracilaRESUMO
The mechanisms for the protection of the human body from viral or bacterial agents are extremely diverse. In one such mechanism, an important role belongs to the cytidine deaminase APOBEC3 family, which is the factor of congenital immunity and protects the organism from numerous viral agents. One of the proteins of this family, APOBEC3G, is able to protect against Human Immunodeficiency Virus type 1 in the absence of viral protein Vif. In turn, Vif opposes APOBEC3G action, causing polyubiquity of the protein and degradation in the proteasome. The review describes possible ways to increase the anti-HIV activity of APOBEC3G, giving it resistance to viral protein Vif, as well as potential approaches to the use of modified APOBEC3G in gene therapy for HIV.
Assuntos
HIV-1 , Produtos do Gene vif do Vírus da Imunodeficiência Humana , Desaminase APOBEC-3G/genética , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Terapia Genética , HIV-1/metabolismo , Humanos , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismoRESUMO
Over the last few decades, protein NMR isotope labeling methods using E. coli based expression have revolutionized the information accessible from biomolecular NMR experiments. Selective labeling of a protein of interest in a multi-protein complex can significantly reduce the number of cross-peaks and allow for study of large protein complexes. However, limitations still remain since some proteins are not stable independently and cannot be separately labeled in either NMR active isotope enriched or unenriched media and reconstituted into a multimeric complex. To overcome this limitation, the LEGO NMR method was previously developed using protein expression plasmids containing T7 or araBAD promoters to separately express proteins in the same E. coli after changing between labeled and unlabeled media. Building on this, we developed a method to label the Human Immunodeficiency Virus type 1 viral infectivity factor (HIV-1 Vif), a monomerically unstable protein, in complex with CBFß, it's host binding partner. We designed a dual promoter plasmid containing both T7 and araBAD promoters to independently control the expression of HIV-1 Vif in NMR active isotope enriched media and CBFß in unenriched media. Using this method, we assigned the backbone resonance and directly observed the binding of HIV-1 Vif with APOBEC3G, a host restriction factor to HIV-1.
Assuntos
Desaminase APOBEC-3G , HIV-1 , Produtos do Gene vif do Vírus da Imunodeficiência Humana , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Escherichia coli , HIV-1/genética , Humanos , Regiões Promotoras Genéticas , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismoRESUMO
HIV-1 encodes accessory proteins that neutralize antiviral restriction factors to ensure its successful replication. One accessory protein, the HIV-1 viral infectivity factor (Vif), is known to promote ubiquitination and proteasomal degradation of the antiviral restriction factor apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G), a cytosine deaminase that leads to hypermutations in the viral DNA and subsequent aberrant viral replication. We have previously demonstrated that the HIV-1 viral transcription mediator Tat activates the host progrowth PI-3-AKT pathway, which in turn promotes HIV-1 replication. Because the HIV-1 Vif protein contains the putative AKT phosphorylation motif RMRINT, here we investigated whether AKT directly phosphorylates HIV-1 Vif to regulate its function. Coimmunoprecipitation experiments showed that AKT and Vif interact with each other, supporting this hypothesis. Using in vitro kinase assays, we further showed that AKT phosphorylates Vif at threonine 20, which promotes its stability, as Vif becomes destabilized after this residue is mutated to alanine. Moreover, expression of dominant-negative kinase-deficient AKT as well as treatment with a chemical inhibitor of AKT increased K48-ubiquitination and proteasomal degradation of HIV-1 Vif. In contrast, constitutively active AKT (Myr-AKT) reduced K48-ubiquitination of Vif to promote its stability. Finally, inhibition of AKT function restored APOBEC3G levels, which subsequently reduced HIV-1 infectivity. Thus, our results establish a novel mechanism of HIV-1 Vif stabilization through AKT-mediated phosphorylation at threonine 20, which reduces APOBEC3G levels and potentiates HIV-1 infectivity.
Assuntos
Desaminase APOBEC-3G , Infecções por HIV , HIV-1 , Produtos do Gene vif do Vírus da Imunodeficiência Humana , Desaminase APOBEC-3G/genética , Desaminase APOBEC-3G/metabolismo , Infecções por HIV/fisiopatologia , Infecções por HIV/virologia , HIV-1/genética , HIV-1/patogenicidade , Humanos , Fosforilação , Estabilidade Proteica , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Treonina/metabolismo , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismoRESUMO
Human immunodeficiency virus (HIV) mutagenesis is driven by a variety of internal and external sources, including the host APOBEC3 (apolipoprotein B mRNA editing enzyme catalytic polypetide-like 3; A3) family of mutagenesis factors, which catalyze G-to-A transition mutations during virus replication. HIV-2 replication is characterized by a relative lack of G-to-A mutations, suggesting infrequent mutagenesis by A3 proteins. To date, the activity of the A3 repertoire against HIV-2 has remained largely uncharacterized, and the mutagenic activity of these proteins against HIV-2 remains to be elucidated. In this study, we provide the first comprehensive characterization of the restrictive capacity of A3 proteins against HIV-2 in cell culture using a dual fluorescent reporter HIV-2 vector virus. We found that A3F, A3G, and A3H restricted HIV-2 infectivity in the absence of Vif and were associated with significant increases in the frequency of viral mutants. These proteins increased the frequency of G-to-A mutations within the proviruses of infected cells as well. A3G and A3H also reduced HIV-2 infectivity via inhibition of reverse transcription and the accumulation of DNA products during replication. In contrast, A3D did not exhibit any restrictive activity against HIV-2, even at higher expression levels. Taken together, these results provide evidence that A3F, A3G, and A3H, but not A3D, are capable of HIV-2 restriction. Differences in A3-mediated restriction of HIV-1 and HIV-2 may serve to provide new insights in the observed mutation profiles of these viruses.
Assuntos
Desaminase APOBEC-3G/metabolismo , Aminoidrolases/metabolismo , Citosina Desaminase/metabolismo , HIV-2 , Desaminase APOBEC-3G/genética , Aminoidrolases/genética , Citidina Desaminase/metabolismo , Citosina Desaminase/genética , Expressão Gênica , Infecções por HIV , HIV-2/genética , Humanos , Mutação , Replicação ViralRESUMO
APOBEC3G (A3G) is a host-encoded cytidine deaminase that potently restricts retroviruses such as HIV-1 and depends on its ability to package into virions. As a consequence of this, HIV-1 protein Vif has evolved to antagonize human A3G by targeting it for ubiquitination and subsequent degradation. There is an ancient arms race between Vif and A3G highlighted by amino acids 128 and 130 in A3G that have evolved under positive selection due to Vif-mediated selective pressure in Old World primates. Nonetheless, not all possible amino acid combinations at these sites have been sampled by nature, and the evolutionary potential of species to resist Vif antagonism is not clear. To explore the evolutionary space of positively selected sites in the Vif-binding region of A3G, we designed a combinatorial mutagenesis screen to introduce all 20 amino acids at sites 128 and 130. Our screen uncovered mutants of A3G with several interesting phenotypes, including loss of antiviral activity and resistance of Vif antagonism. However, HIV-1 Vif exhibited remarkable flexibility in antagonizing A3G 128 and 130 mutants, which significantly reduces viable Vif resistance strategies for hominid primates. Importantly, we find that broadened Vif specificity was conferred through loop 5 adaptations that were required for cross-species adaptation from Old World monkey A3G to hominid A3G. Our evidence suggests that Vif adaptation to novel A3G interfaces during cross-species transmission may train Vif toward broadened specificity that can further facilitate cross-species transmissions and raise the barrier to host resistance. IMPORTANCE APOBEC3G (A3G) is an antiviral protein that potently restricts retroviruses like HIV. In turn, the HIV-1 protein Vif has evolved to antagonize A3G through degradation. Two rapidly evolving sites in A3G confer resistance to unadapted Vif and act as a barrier to cross-species transmission of retroviruses. We recently identified a single amino acid mutation in a simian immunodeficiency virus (SIV) Vif that contributed to the cross-species origins of SIV infecting chimpanzee and, ultimately, the HIV-1 pandemic. This mutation broadened specificity of this Vif to both antagonize the A3G of its host while simultaneously overcoming the A3G barrier in the great apes. In this work, we explore the evolutionary space of human A3G at these rapidly evolving sites to understand if the broadened Vif specificity gained during cross-species transmission confers an advantage to HIV-1 Vif in its host-virus arms race with A3G.
Assuntos
Desaminase APOBEC-3G/antagonistas & inibidores , HIV-1/fisiologia , Produtos do Gene vif do Vírus da Imunodeficiência Humana/antagonistas & inibidores , Desaminase APOBEC-3G/genética , Adaptação Fisiológica/genética , Aminoácidos , Animais , Infecções por HIV/transmissão , Infecções por HIV/virologia , HIV-1/genética , Interações entre Hospedeiro e Microrganismos , Humanos , Mutação , Primatas , Vírus da Imunodeficiência Símia/genética , Zoonoses Virais/transmissão , Zoonoses Virais/virologia , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genéticaRESUMO
The host restriction factor APOBEC3G (A3G) inhibits an extensive variety of viruses, including retroviruses, DNA viruses, and RNA viruses. Our study shows that A3G inhibits enterovirus 71 (EV71) and coxsackievirus A16 (CA16) via competitively binding the 5' untranslated region (UTR) with the host protein poly(C)-binding protein 1 (PCBP1), which is required for the replication of multiple EVs. However, whether A3G inhibits other EVs in addition to EV71 and CA16 has not been investigated. Here, we demonstrate that A3G could inhibit the replication of EVD68, which requires PCBP1 for its replication, but not CA6, which does not require PCBP1 for replication. Further investigation revealed that the nucleic-acid-binding activity of A3G is required for EVD68 restriction, similar to the mechanism presented for EV71 restriction. Mechanistically, A3G competitively binds to the cloverleaf (1 to 123 nucleotides [nt]) and the stem-loop IV (234 to 446 nt) domains of the EVD68 5' UTR with PCBP1, thereby inhibiting the 5' UTR activity of EVD68; by contrast, A3G does not interact with CA6 5' UTR, resulting in no effect on CA6 replication. Moreover, the nonstructural protein 2C, encoded by EVD68, overcomes A3G suppression by inducing A3G degradation via the autophagy-lysosome pathway. Our findings revealed that A3G might have broad-spectrum antiviral activity against multiple EVs through this general mechanism, and they might provide important information for the development of an anti-EV strategy. IMPORTANCE As the two major pathogens causing hand, foot, and mouth disease (HFMD), enterovirus 71 (EV71) and coxsackievirus A16 (CA16) attract a lot of attention for the study of their pathogenesis, their involvement with cellular proteins, and so on. However, other EVs such as CA6 and EVD68 constantly occur sporadically or have spread worldwide in recent years. Therefore, more information related to these EVs is needed in order to develop a broad-spectrum anti-EV inhibitor. In this study, we first reveal that the protein poly(C)-binding protein 1 (PCBP1), involved in PV- and EV71 virus replication, is also required for the replication of EVD68, but not for the replication of CA6. Next, we found that the host-restriction factor A3G specifically inhibits the replication of EVD68, but not the replication of CA6, by competitively binding to the 5' UTR of EVD68 along with PCBP1. Our findings broaden knowledge related to EV replication and the interplay between EVs and host factors.