1
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McGuinness CF, Black MA, Dunbier AK. Restriction site associated DNA sequencing for tumour mutation burden estimation and mutation signature analysis. Cancer Med 2023; 12:21545-21560. [PMID: 37974533 PMCID: PMC10726921 DOI: 10.1002/cam4.6711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 11/05/2023] [Accepted: 11/06/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Genome-wide measures of genetic disruption such as tumour mutation burden (TMB) and mutation signatures are emerging as useful biomarkers to stratify patients for treatment. Clinicians commonly use cancer gene panels for tumour mutation burden estimation, and whole genome sequencing is the gold standard for mutation signature analysis. However, the accuracy and cost associated with these assays limits their utility at scale. METHODS WGS data from 560 breast cancer patients was used for in silico library simulations to evaluate the accuracy of an FDA approved cancer gene panel as well as restriction enzyme associated DNA sequencing (RADseq) libraries for TMB estimation and mutation signature analysis. We also transfected a mouse mammary cell line with APOBEC enzymes and sequenced resulting clones to evaluate the efficacy of RADseq in an experimental setting. RESULTS RADseq had improved accuracy of TMB estimation and derivation of mutation profiles when compared to the FDA approved cancer panel. Using simulated immune checkpoint blockade (ICB) trials, we show that inaccurate TMB estimation leads to a reduction in power for deriving an optimal TMB cutoff to stratify patients for immune checkpoint blockade treatment. Additionally, prioritisation of APOBEC hypermutated tumours in these trials optimises TMB cutoff determination for breast cancer. The utility of RADseq in an experimental setting was also demonstrated, based on characterisation of an APOBEC mutation signature in an APOBEC3A transfected mouse cell line. CONCLUSION In conclusion, our work demonstrates that RADseq has the potential to be used as a cost-effective, accurate solution for TMB estimation and mutation signature analysis by both clinicians and basic researchers.
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Affiliation(s)
- Conor F. McGuinness
- Department of BiochemistryUniversity of OtagoDunedinNew Zealand
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyThe University of MelbourneMelbourneVictoriaAustralia
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2
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Hu X, Biswas A, De S. KMT2C-deficient tumors have elevated APOBEC mutagenesis and genomic instability in multiple cancers. NAR Cancer 2022; 4:zcac023. [PMID: 35898555 PMCID: PMC9310081 DOI: 10.1093/narcan/zcac023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 07/03/2022] [Accepted: 07/19/2022] [Indexed: 11/26/2022] Open
Abstract
The histone methyltransferase KMT2C is among the most frequently mutated epigenetic modifier genes in cancer and plays an essential role in MRE11-dependent DNA replication fork restart. However, the effects of KMT2C deficiency on genomic instability during tumorigenesis are unclear. Analyzing 9,663 tumors from 30 cancer cohorts, we report that KMT2C mutant tumors have a significant excess of APOBEC mutational signatures in several cancer types. We show that KMT2C deficiency promotes APOBEC expression and deaminase activity, and compromises DNA replication speed and delays fork restart, facilitating APOBEC mutagenesis targeting single stranded DNA near stalled forks. APOBEC-mediated mutations primarily accumulate during early replication and tend to cluster along the genome and also in 3D nuclear domains. Excessive APOBEC mutational signatures in KMT2C mutant tumors correlate with elevated genome maintenance defects and signatures of homologous recombination deficiency. We propose that KMT2C deficiency is a likely promoter of APOBEC mutagenesis, which fosters further genomic instability during tumor progression in multiple cancer types.
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Affiliation(s)
- Xiaoju Hu
- Rutgers Cancer Institute of New Jersey, Rutgers the State University of New Jersey , New Brunswick, NJ 08901, USA
| | - Antara Biswas
- Rutgers Cancer Institute of New Jersey, Rutgers the State University of New Jersey , New Brunswick, NJ 08901, USA
| | - Subhajyoti De
- Rutgers Cancer Institute of New Jersey, Rutgers the State University of New Jersey , New Brunswick, NJ 08901, USA
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3
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Repair of APOBEC3G-Mutated Retroviral DNA In Vivo Is Facilitated by the Host Enzyme Uracil DNA Glycosylase 2. J Virol 2021; 95:e0124421. [PMID: 34468176 DOI: 10.1128/jvi.01244-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apolipoprotein B mRNA editing enzyme catalytic subunit 3 (APOBEC3) proteins are critical for the control of infection by retroviruses. These proteins deaminate cytidines in negative-strand DNA during reverse transcription, leading to G-to-A changes in coding strands. Uracil DNA glycosylase (UNG) is a host enzyme that excises uracils in genomic DNA, which the base excision repair machinery then repairs. Whether UNG removes uracils found in retroviral DNA after APOBEC3-mediated mutation is not clear, and whether this occurs in vivo has not been demonstrated. To determine if UNG plays a role in the repair of retroviral DNA, we used APOBEC3G (A3G) transgenic mice which we showed previously had extensive deamination of murine leukemia virus (MLV) proviruses. The A3G transgene was crossed onto an Ung and mouse Apobec3 knockout background (UNG-/-APO-/-), and the mice were infected with MLV. We found that virus infection levels were decreased in A3G UNG-/-APO-/- compared with A3G APO-/- mice. Deep sequencing of the proviruses showed that there were significantly higher levels of G-to-A mutations in proviral DNA from A3G transgenic UNG-/-APO-/- than A3G transgenic APO-/- mice, suggesting that UNG plays a role in the repair of uracil-containing proviruses. In in vitro studies, we found that cytoplasmic viral DNA deaminated by APOBEC3G was uracilated. In the absence of UNG, the uracil-containing proviruses integrated at higher levels into the genome than those made in the presence of UNG. Thus, UNG also functions in the nucleus prior to integration by nicking uracil-containing viral DNA, thereby blocking integration. These data show that UNG plays a critical role in the repair of the damage inflicted by APOBEC3 deamination of reverse-transcribed DNA. IMPORTANCE While APOBEC3-mediated mutation of retroviruses is well-established, what role the host base excision repair enzymes play in correcting these mutations is not clear. This question is especially difficult to address in vivo. Here, we use a transgenic mouse developed by our lab that expresses human APOBEC3G and also lacks the endogenous uracil DNA glycosylase (Ung) gene and show that UNG removes uracils introduced by this cytidine deaminase in MLV reverse transcripts, thereby reducing G-to-A mutations in proviruses. Furthermore, our data suggest that UNG removes uracils at two stages in infection-first, in unintegrated nuclear viral reverse-transcribed DNA, resulting in its degradation; and second, in integrated proviruses, resulting in their repair. These data suggest that retroviruses damaged by host cytidine deaminases take advantage of the host DNA repair system to overcome this damage.
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4
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Luo MT, Mu D, Yang X, Luo RH, Zheng HY, Chen M, Guo YQ, Zheng YT. Tree Shrew Cells Transduced with Human CD4 and CCR5 Support Early Steps of HIV-1 Replication, but Viral Infectivity Is Restricted by APOBEC3. J Virol 2021; 95:e0002021. [PMID: 34076481 PMCID: PMC8312864 DOI: 10.1128/jvi.00020-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
The host range of human immunodeficiency virus type 1 (HIV-1) is narrow. Therefore, using ordinary animal models to study HIV-1 replication, pathogenesis, and therapy is impractical. The lack of applicable animal models for HIV-1 research spurred our investigation on whether tree shrews (Tupaia belangeri chinensis), which are susceptible to many types of human viruses, can act as an animal model for HIV-1. Here, we report that tree shrew primary cells are refractory to wild-type HIV-1 but support the early replication steps of HIV-1 pseudotyped with the vesicular stomatitis virus glycoprotein envelope (VSV-G), which can bypass entry receptors. The exogenous expression of human CD4 renders the tree shrew cell line infectible to X4-tropic HIV-1IIIB, suggesting that tree shrew CXCR4 is a functional HIV-1 coreceptor. However, tree shrew cells did not produce infectious HIV-1 progeny virions, even with the human CD4 receptor. Subsequently, we identified tree shrew (ts) apolipoprotein B editing catalytic polypeptide 3 (tsAPOBEC3) proteins as active inhibitors of HIV-1 particle infectivity, with virus infectivity reduced 10- to 1,000-fold. Unlike human APOBEC3G, the tsA3Z2c-Z1b protein was not degraded by the HIV-1 viral infectivity factor (Vif) but markedly restricted HIV-1 replication through mutagenicity and reverse transcription inhibition. The pooled knockout of tsA3Z2c-Z1b partially restored the infectivity of the HIV-1 progeny. This work suggests that tsAPOBEC3 proteins serve as an additional barrier to the development of HIV-1 tree shrew models, even when virus entry is overcome by exogenous expression of human CD4. IMPORTANCE The development of animal models is critical for studying human diseases and their pathogenesis and for evaluating drug and vaccine efficacy. For improved AIDS research, the ideal animal model of HIV-1 infection should be a small laboratory mammal that closely mimics virus replication in humans. Tree shrews exhibit considerable potential as animal models for the study of human diseases and therapeutic responses. Here, we report that human CD4-expressing tree shrew cells support the early steps of HIV-1 replication and that tree shrew CXCR4 is a functional coreceptor of HIV-1. However, tree shrew cells harbor additional restrictions that lead to the production of HIV-1 virions with low infectivity. Thus, the tsAPOBEC3 proteins are partial barriers to developing tree shrews as an HIV-1 model. Our results provide insight into the genetic basis of HIV inhibition in tree shrews and build a foundation for the establishment of gene-edited tree shrew HIV-1-infected models.
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Affiliation(s)
- Meng-Ting Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Dan Mu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China
| | - Xiang Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Rong-Hua Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Hong-Yi Zheng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Min Chen
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Ying-Qi Guo
- National Resource Center for Non-Human Primates, and National Research Facility for Phenotypic & Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Yong-Tang Zheng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Center for Bio-safety Mega-Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
- National Resource Center for Non-Human Primates, and National Research Facility for Phenotypic & Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
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5
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Wang L, Xue W, Zhang H, Gao R, Qiu H, Wei J, Zhou L, Lei YN, Wu X, Li X, Liu C, Wu J, Chen Q, Ma H, Huang X, Cai C, Zhang Y, Yang B, Yin H, Yang L, Chen J. Eliminating base-editor-induced genome-wide and transcriptome-wide off-target mutations. Nat Cell Biol 2021; 23:552-563. [PMID: 33972728 DOI: 10.1038/s41556-021-00671-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 03/26/2021] [Indexed: 12/17/2022]
Abstract
The fusion of CRISPR-Cas9 with cytidine deaminases leads to base editors (BEs) capable of programmable C-to-T editing, which has potential in clinical applications but suffers from off-target (OT) mutations. Here, we used a cleavable deoxycytidine deaminase inhibitor (dCDI) domain to construct a transformer BE (tBE) system that induces efficient editing with only background levels of genome-wide and transcriptome-wide OT mutations. After being produced, the tBE remains inactive at OT sites with the fusion of a cleavable dCDI, therefore eliminating unintended mutations. When binding at on-target sites, the tBE is transformed to cleave off the dCDI domain and catalyses targeted deamination for precise base editing. After delivery into mice through a dual-adeno-associated virus (AAV) system, the tBE system created a premature stop codon in Pcsk9 and significantly reduced serum PCSK9, resulting in a ~30-40% decrease in total cholesterol. The development of tBE establishes a highly specific base editing system and its in vivo efficacy has potential for therapeutic applications.
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Affiliation(s)
- Lijie Wang
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Wei Xue
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hongxia Zhang
- Department of Urology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China.,Department of Pathology, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Runze Gao
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Houyuan Qiu
- Department of Urology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China.,Department of Rheumatology and Immunology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Jia Wei
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lina Zhou
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yun-Ni Lei
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiaocheng Wu
- Department of Rheumatology and Immunology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Xiao Li
- Department of Orthopedics, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Chengfang Liu
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jing Wu
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Qiubing Chen
- Department of Urology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China.,Department of Pathology, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Hanhui Ma
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xingxu Huang
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Cheguo Cai
- Department of Orthopedics, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Ying Zhang
- Department of Rheumatology and Immunology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Bei Yang
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Hao Yin
- Department of Urology, Frontier Science Center for Immunology and Metabolism Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China. .,Department of Pathology, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China.
| | - Li Yang
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Jia Chen
- School of Life Science and Technology and Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China. .,Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China. .,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
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6
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Abstract
This study examined for the first time the in vivo function of the serine incorporator (SERINC) proteins during retrovirus infection. SERINC3 and SERINC5 (SERINC3/5) restrict a number of retroviruses, including human immunodeficiency virus 1 (HIV-1) and murine leukemia virus (MLV), by blocking their entry into cells. Nevertheless, HIV-1 and MLV encode factors, Nef and glycosylated Gag, respectively, that counteract SERINC3/5 in vitro. We recently developed SERINC3 and SERINC5 knockout mice to examine the in vivo function of these genes. We found that SERINC5 restriction is dependent on the absence of glycosylated Gag and the expression of a specific viral envelope glycoprotein. On the other hand, SERINC3 had no antiviral function. Our findings have implications for the development of therapeutics that target SERINC5 during retrovirus infection. The serine incorporator (SERINC) proteins are multipass transmembrane proteins that affect sphingolipid and phosphatidylserine synthesis. Human SERINC5 and SERINC3 were recently shown to possess antiretroviral activity for a number of retroviruses, including human immunodeficiency virus (HIV), murine leukemia virus (MLV), and equine infectious anemia virus (EIAV). In the case of MLV, the glycosylated Gag (glyco-Gag) protein was shown to counteract SERINC5-mediated restriction in in vitro experiments and the viral envelope was found to determine virion sensitivity or resistance to SERINC5. However, nothing is known about the in vivo function of SERINC5. Antiretroviral function of a host factor in vitro is not always associated with antiretroviral function in vivo. Using SERINC5−/− mice that we had generated, we showed that mouse SERINC5 (mSERINC5) restriction of MLV infection in vivo is influenced not only by glyco-Gag but also by the retroviral envelope. Finally, we also examined the in vivo function of the other SERINC gene with known antiretroviral functions, SERINC3. By using SERINC3−/− mice, we found that the murine homologue, mSERINC3, had no antiretroviral role either in vivo or in vitro. To our knowledge, this report provides the first data showing that SERINC5 restricts retrovirus infection in vivo and that restriction of retrovirus infectivity in vivo is dependent on the presence of both glyco-Gag and the viral envelope.
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7
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Hakata Y, Li J, Fujino T, Tanaka Y, Shimizu R, Miyazawa M. Mouse APOBEC3 interferes with autocatalytic cleavage of murine leukemia virus Pr180gag-pol precursor and inhibits Pr65gag processing. PLoS Pathog 2019; 15:e1008173. [PMID: 31830125 PMCID: PMC6907756 DOI: 10.1371/journal.ppat.1008173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/30/2019] [Indexed: 01/01/2023] Open
Abstract
Mouse APOBEC3 (mA3) inhibits murine leukemia virus (MuLV) replication by a deamination-independent mechanism in which the reverse transcription is considered the main target process. However, other steps in virus replication that can be targeted by mA3 have not been examined. We have investigated the possible effect of mA3 on MuLV protease-mediated processes and found that mA3 binds both mature viral protease and Pr180gag-pol precursor polyprotein. Using replication-competent MuLVs, we also show that mA3 inhibits the processing of Pr65 Gag precursor. Furthermore, we demonstrate that the autoprocessing of Pr180gag-pol is impeded by mA3, resulting in reduced production of mature viral protease. This reduction appears to link with the above inefficient Pr65gag processing in the presence of mA3. Two major isoforms of mA3, exon 5-containing and -lacking ones, equally exhibit this antiviral activity. Importantly, physiologically expressed levels of mA3 impedes both Pr180gag-pol autocatalysis and Pr65gag processing. This blockade is independent of the deaminase activity and requires the C-terminal region of mA3. These results suggest that the above impairment of Pr180gag-pol autoprocessing may significantly contribute to the deaminase-independent antiretroviral activity exerted by mA3. Soon after the identification of the polynucleotide cytidine deaminase APOBEC3 as a host restriction factor against vif-deficient HIV, it was noticed that deamination-independent mechanisms are involved in the inhibition of viral replication in addition to the deaminase-dependent mechanism. We previously showed that mouse APOBEC3 (mA3) physiologically restricted mouse retrovirus replication in their natural hosts without causing significant G-to-A hypermutations. Inhibition of reverse transcription is reported to be the most plausible mechanism for the deamination-independent antiretroviral function. However, it remains unknown whether the inhibition of reverse transcription is the only way to explain the whole picture of deamination-independent antiviral activity exerted by APOBEC3. Here we show that mA3 targets the autoprocessing of Pr180gag-pol polyprotein. This activity does not require the deaminase catalytic center and mainly exerted by the C-terminal half of mA3. mA3 physically interacts with murine retroviral protease and its precursor Pr180gag-pol. mA3-induced disruption of the autocatalytic Pr180gag-pol cleavage leads to a significant reduction of mature viral protease, resulting in the inhibition of Pr65gag processing to mature Gag proteins. As the Pr180gag-pol autoprocessing is necessary for the maturation of other viral enzymes including the reverse transcriptase, its inhibition by host APOBEC3 may precede the previously described impairment of reverse transcription. Our discovery may lead to the development of novel antiretroviral drugs through the future identification of detailed molecular interfaces between retroviral Gag-Pol polyprotein and APOBEC3.
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Affiliation(s)
- Yoshiyuki Hakata
- Department of Immunology, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
- * E-mail: (YH); (MM)
| | - Jun Li
- Department of Immunology, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
- Ijunkai Medical Oncology, Endoscopy Clinic, Sakai-ku, Sakai, Osaka, Japan
| | - Takahiro Fujino
- Division of Analytical Bio-Medicine, Advanced Research Support Center (ADRES), Ehime University, Shitsukawa, Toon, Ehime, Japan
| | - Yuki Tanaka
- Division of Analytical Bio-Medicine, Advanced Research Support Center (ADRES), Ehime University, Shitsukawa, Toon, Ehime, Japan
| | - Rie Shimizu
- Department of Immunology, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
| | - Masaaki Miyazawa
- Department of Immunology, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
- Kindai University Anti-Aging Center, Higashiosaka, Osaka, Japan
- * E-mail: (YH); (MM)
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8
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Evgin L, Huff AL, Kottke T, Thompson J, Molan AM, Driscoll CB, Schuelke M, Shim KG, Wongthida P, Ilett EJ, Smith KK, Harris RS, Coffey M, Pulido JS, Pandha H, Selby PJ, Harrington KJ, Melcher A, Vile RG. Suboptimal T-cell Therapy Drives a Tumor Cell Mutator Phenotype That Promotes Escape from First-Line Treatment. Cancer Immunol Res 2019; 7:828-840. [PMID: 30940643 PMCID: PMC7003288 DOI: 10.1158/2326-6066.cir-18-0013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 05/14/2018] [Accepted: 03/27/2019] [Indexed: 12/19/2022]
Abstract
Antitumor T-cell responses raised by first-line therapies such as chemotherapy, radiation, tumor cell vaccines, and viroimmunotherapy tend to be weak, both quantitatively (low frequency) and qualitatively (low affinity). We show here that T cells that recognize tumor-associated antigens can directly kill tumor cells if used at high effector-to-target ratios. However, when these tumor-reactive T cells were present at suboptimal ratios, direct T-cell-mediated tumor cell killing was reduced and the ability of tumor cells to evolve away from a coapplied therapy (oncolytic or suicide gene therapy) was promoted. This T-cell-mediated increase in therapeutic resistance was associated with C to T transition mutations that are characteristic of APOBEC3 cytosine deaminase activity and was induced through a TNFα and protein kinase C-dependent pathway. Short hairpin RNA inhibition of endogenous APOBEC3 reduced rates of tumor escape from oncolytic virus or suicide gene therapy to those seen in the absence of antitumor T-cell coculture. Conversely, overexpression of human APOBEC3B in tumor cells enhanced escape from suicide gene therapy and oncolytic virus therapy both in vitro and in vivo Our data suggest that weak affinity or low frequency T-cell responses against tumor antigens may contribute to the ability of tumor cells to evolve away from first-line therapies. We conclude that immunotherapies need to be optimized as early as possible so that, if they do not kill the tumor completely, they do not promote treatment resistance.
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Affiliation(s)
- Laura Evgin
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Amanda L Huff
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy Kottke
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Jill Thompson
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Amy M Molan
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | | | | | - Kevin G Shim
- Department of Immunology, Mayo Clinic, Rochester, Minnesota
| | | | - Elizabeth J Ilett
- Leeds Institute of Cancer and Pathology, St. James' University Hospital, Leeds, United Kingdom
| | | | - Reuben S Harris
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Matt Coffey
- Oncolytics Biotech Incorporated, Calgary, Canada
| | - Jose S Pulido
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
| | - Hardev Pandha
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Peter J Selby
- Leeds Institute of Cancer and Pathology, St. James' University Hospital, Leeds, United Kingdom
| | | | - Alan Melcher
- Institute of Cancer Research, London, United Kingdom
| | - Richard G Vile
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota.
- Department of Immunology, Mayo Clinic, Rochester, Minnesota
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9
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Deaminase-Dead Mouse APOBEC3 Is an In Vivo Retroviral Restriction Factor. J Virol 2018; 92:JVI.00168-18. [PMID: 29593034 DOI: 10.1128/jvi.00168-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/17/2018] [Indexed: 11/20/2022] Open
Abstract
The apolipoprotein B editing complex 3 (APOBEC3) proteins are potent retroviral restriction factors that are under strong positive selection, both in terms of gene copy number and sequence diversity. A common feature of all the members of the APOBEC3 family is the presence of one or two cytidine deamination domains, essential for cytidine deamination of retroviral reverse transcripts as well as packaging into virions. Several studies have indicated that human and mouse APOBEC3 proteins restrict retrovirus infection via cytidine deaminase (CD)-dependent and -independent means. To understand the relative contribution of CD-independent restriction in vivo, we created strains of transgenic mice on an APOBEC3 knockout background that express a deaminase-dead mouse APOBEC3 due to point mutations in both CD domains (E73Q/E253Q). Here, we show that the CD-dead APOBEC3 can restrict murine retroviruses in vivo Moreover, unlike the wild-type protein, the mutant APOBEC3 is not packaged into virions but acts only as a cell-intrinsic restriction factor that blocks reverse transcription by incoming viruses. Finally, we show that wild-type and CD-dead mouse APOBEC3 can bind to murine leukemia virus (MLV) reverse transcriptase. Our findings suggest that the mouse APOBEC3 cytidine deaminase activity is not required for retrovirus restriction.IMPORTANCE APOBEC3 proteins are important host cellular restriction factors essential for restricting retrovirus infection by causing mutations in the virus genome and by blocking reverse transcription. While both methods of restriction function in vitro, little is known about their role during in vivo infection. By developing transgenic mice with mutations in the cytidine deamination domains needed for enzymatic activity and interaction with viral RNA, we show that APOBEC3 proteins can still restrict in vivo infection by interacting with reverse transcriptase and blocking its activity. These studies demonstrate that APOBEC3 proteins have evolved multiple means for blocking retrovirus infection and that all of these means function in vivo.
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10
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Asymmetric Modification of Hepatitis B Virus (HBV) Genomes by an Endogenous Cytidine Deaminase inside HBV Cores Informs a Model of Reverse Transcription. J Virol 2018; 92:JVI.02190-17. [PMID: 29491156 DOI: 10.1128/jvi.02190-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Accepted: 02/20/2018] [Indexed: 02/07/2023] Open
Abstract
Cytidine deaminases inhibit replication of a broad range of DNA viruses by deaminating cytidines on single-stranded DNA (ssDNA) to generate uracil. While several lines of evidence have revealed hepatitis B virus (HBV) genome editing by deamination, it is still unclear which nucleic acid intermediate of HBV is modified. Hepatitis B virus has a relaxed circular double-stranded DNA (rcDNA) genome that is reverse transcribed within virus cores from a RNA template. The HBV genome also persists as covalently closed circular DNA (cccDNA) in the nucleus of an infected cell. In the present study, we found that in HBV-producing HepAD38 and HepG2.2.15 cell lines, endogenous cytidine deaminases edited 10 to 25% of HBV rcDNA genomes, asymmetrically with almost all mutations on the 5' half of the minus strand. This region corresponds to the last half of the minus strand to be protected by plus-strand synthesis. Within this half of the genome, the number of mutations peaks in the middle. Overexpressed APOBEC3A and APOBEC3G could be packaged in HBV capsids but did not change the amount or distribution of mutations. We found no deamination on pregenomic RNA (pgRNA), indicating that an intact genome is encapsidated and deaminated during or after reverse transcription. The deamination pattern suggests a model of rcDNA synthesis in which pgRNA and then newly synthesized minus-sense single-stranded DNA are protected from deaminase by interaction with the virus capsid; during plus-strand synthesis, when enough dsDNA has been synthesized to displace the remaining minus strand from the capsid surface, the single-stranded DNA becomes deaminase sensitive.IMPORTANCE Host-induced mutation of the HBV genome by APOBEC proteins may be a path to clearing the virus. We examined cytidine-to-thymidine mutations in the genomes of HBV particles grown in the presence or absence of overexpressed APOBEC proteins. We found that genomes were subjected to deamination activity during reverse transcription, which takes place within the virus capsid. These observations provide a direct insight into the mechanics of reverse transcription, suggesting that newly synthesized dsDNA displaces ssDNA from the capsid walls, making the ssDNA accessible to deaminase activity.
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11
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Renner TM, Bélanger K, Lam C, Gerpe MCR, McBane JE, Langlois MA. Full-Length Glycosylated Gag of Murine Leukemia Virus Can Associate with the Viral Envelope as a Type I Integral Membrane Protein. J Virol 2018; 92:e01530-17. [PMID: 29298890 PMCID: PMC5827372 DOI: 10.1128/jvi.01530-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/20/2017] [Indexed: 11/20/2022] Open
Abstract
The glycosylated Gag protein (gPr80) of murine leukemia viruses (MLVs) has been shown to exhibit multiple roles in facilitating retrovirus release, infection, and resistance to host-encoded retroviral restriction factors, such as APOBEC3, SERINC3, and SERINC5. One way in which gPr80 helps MLVs to escape host innate immune restriction is by increasing capsid stability, a feature that protects viral replication intermediates from being detected by cytosolic DNA sensors. gPr80 also increases the resistance of MLVs to deamination and restriction by mouse APOBEC3 (mA3). How the gPr80 accessory protein, with its three N-linked glycosylation sites, contributes to these resistance mechanisms is still not fully understood. Here we further characterized the function of gPr80 and, more specifically, revealed that the asparagines targeted for glycosylation in gPr80 also contribute to capsid stability through their parallel involvement in the Pr65 Gag structural polyprotein. In fact, we demonstrate that sensitivity to deamination by the mA3 and human A3 proteins is directly linked to capsid stability. We also show that full-length gPr80 is detected in purified viruses. However, our results suggest that gPr80 is inserted in the NexoCcyto orientation of a type I integral membrane protein. Additionally, our experiments have revealed the existence of a large population of Env-deficient virus-like particles (VLPs) harboring gPr80 inserted in the opposite (NcytoCexo) polarity, which is typical of type II integral membrane proteins. Overall this study provides new insight into the complex nature of the MLV gPr80 accessory protein.IMPORTANCE Viruses have evolved numerous strategies to infect, spread in, and persist in their hosts. Here we analyze the details of how the MLV-encoded glycosylated Gag (gPr80) protein protects the virus from being restricted by host innate immune defenses. gPr80 is a variant of the structural Pr65 Gag protein with an 88-amino-acid extended leader sequence that directs the protein for translation and glycosylation in the endoplasmic reticulum. This study dissects the specific contributions of gPr80 glycans and capsid stability in helping the virus to infect cells, spread, and counteract the effects of the host intrinsic restriction factor APOBEC3. Overall this study provides further insight into the elusive role of the gPr80 protein.
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Affiliation(s)
- Tyler Milston Renner
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Kasandra Bélanger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Cindy Lam
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - María Carla Rosales Gerpe
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Joanne Eileen McBane
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Marc-André Langlois
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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12
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Luo MT, Fan Y, Mu D, Yao YG, Zheng YT. Molecular cloning and characterization of APOBEC3 family in tree shrew. Gene 2017; 646:143-152. [PMID: 29292195 DOI: 10.1016/j.gene.2017.12.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 12/27/2017] [Accepted: 12/28/2017] [Indexed: 11/17/2022]
Abstract
The APOBEC3 family is a series antiviral factors that inhibit the replication of many viruses, such as HIV-1 and HBV. Tree shrews (Tupaia belangeri) possess great potential as an animal model for human diseases and therapeutic responses. However, the APOBEC3 family is unknown in tree shrews. Recent work has showed the presence of the APOBEC3 family in tree shrews. In this work, the cDNA sequences of five APOBEC3 members were identified in tree shrews, namely, tsAPOBEC3A, -3C, -3F, -3G and -3H. The results showed that their sequences encoded a zinc (Z)-coordinating-domain as a characteristic of APOBEC3 proteins. Phylogenetic analysis revealed that the tree shrew APOBEC3 (tsAPOBEC3) genes have occurred independently and that they are clustered with other mammalian APOBEC3 members. Transcript expression analysis indicated that tsAPOBEC3 genes are constitutively expressed, and high in immune-related tissues. tsAPOBEC3 gene expression was up-regulated in hepatocytes and PBMCs by IFN-α stimulation. Finally, tsAPOBEC3 proteins could edit both sides of DNA by inserting G→A and C→T hypermutations. Overall, the results suggest that the tsAPOBEC3 family could play a key role in defense immunity through distinct editing mechanisms. Our results provided insights into the genetic basis for the development of a tree shrew model for studying viral infection. Future studies will focus on deepening our understanding on the antiviral functions of these editing enzymes in tree shrew.
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Affiliation(s)
- Meng-Ting Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China
| | - Yu Fan
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China
| | - Dan Mu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China
| | - Yong-Gang Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China; Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Yong-Tang Zheng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China; Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; KIZ-SU Joint Laboratory of Animal Models and Drug Development, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215006, China..
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13
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Jaguva Vasudevan AA, Hofmann H, Willbold D, Häussinger D, Koenig BW, Münk C. Enhancing the Catalytic Deamination Activity of APOBEC3C Is Insufficient to Inhibit Vif-Deficient HIV-1. J Mol Biol 2017; 429:1171-1191. [DOI: 10.1016/j.jmb.2017.03.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/08/2017] [Accepted: 03/08/2017] [Indexed: 12/17/2022]
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14
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Yoshikawa T, Wu J, Otsuka M, Kishikawa T, Suzuki N, Takata A, Ohno M, Ishibashi R, Yamagami M, Nakagawa R, Kato N, Miyazawa M, Han J, Koike K. Repression of MicroRNA Function Mediates Inflammation-associated Colon Tumorigenesis. Gastroenterology 2017; 152:631-643. [PMID: 27825961 DOI: 10.1053/j.gastro.2016.10.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 10/16/2016] [Accepted: 10/31/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Little is known about the mechanisms by which chronic inflammation contributes to carcinogenesis, such as the development of colon tumors in patients with inflammatory bowel diseases. Specific microRNA (miRNAs) can function as suppressors or oncogenes, and widespread alterations in miRNA expression have been associated with tumorigenesis. We studied whether alterations in miRNA function contribute to inflammation-associated colon carcinogenesis. METHODS We studied the effects of inflammatory cytokines, such as tumor necrosis factor, interleukin-1α (IL1A), and IL1β (IL1B), on miRNA function, measured by activity of reporter constructs containing miRNA-binding sites in their 3' untranslated regions, in human 293T embryonic kidney, Caco-2, HT29, and HCT116 colon carcinoma cells, as well as dicer+/+ and dicer-/-, and Apobec3+/+ and Apobec3-/- mouse embryonic fibroblasts. Cells were analyzed by immunoblots, immunohistochemistry, and flow cytometry. We generated transgenic mice expressing reporter constructs regulated by LET7B, MIR122, and MIR29b response elements; some mice were given injections of miRNA inhibitors (anti-MIR122 or anti-LET7B), a negative control, or tumor necrosis factor. Liver tissues were collected and analyzed by immunoblotting. Reporter mice were given azoxymethane followed by dextran sulfate sodium to induce colitis and colon tumors; some mice were given the ROCK inhibitor fasudil along with these agents (ROCK inhibitors increase miRNA function). Colon tissues were collected and analyzed by immunohistochemistry, immunoblots, and fluorescence microscopy. RESULTS Incubation of cell lines with inflammatory cytokines reduced the ability of miRNAs to down-regulate expression from reporter constructs; dicer was required for this effect, so these cytokines relieve miRNA-dependent reductions in expression. The cytokines promoted degradation of APOBEC3G, which normally promotes miRNA loading into argonaute 2-related complexes. Mice with colitis had reduced miRNA function, based on increased expression of reporter genes. Administration of fasudil to mice did not reduce the severity of colitis that developed but greatly reduced the numbers of colon tumors formed (mean 2 tumors/colon in mice given fasudil vs 9 tumors/colon in mice given control agent). We made similar observations in IL10-deficient mice. CONCLUSIONS We found inflammatory cytokines to reduce the activities of miRNAs. In mice with colitis, activities of miRNAs are reduced; administration of an agent that increases miRNA function prevents colon tumor formation in these mice. This pathway might be targeted to prevent colon carcinogenesis in patients with inflammatory bowel diseases.
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Affiliation(s)
- Takeshi Yoshikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Jianfeng Wu
- State Key Laboratory of Cellular Stress Biology and School of Life Sciences, Xiamen University, Xiamen, China
| | - Motoyuki Otsuka
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Japan Science and Technology Agency, PRESTO, Kawaguchi, Saitama, Japan.
| | - Takahiro Kishikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nobumi Suzuki
- Division of Gastroenterology, The Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan
| | - Akemi Takata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Motoko Ohno
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Rei Ishibashi
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mari Yamagami
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ryo Nakagawa
- Division of Advanced Genome Medicine, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Naoya Kato
- Division of Advanced Genome Medicine, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Masaaki Miyazawa
- Department of Immunology, Faculty of Medicine, Kindai University, Osaka-Sayama, Osaka, Japan
| | - Jiahuai Han
- State Key Laboratory of Cellular Stress Biology and School of Life Sciences, Xiamen University, Xiamen, China.
| | - Kazuhiko Koike
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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15
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Abstract
The AID/APOBEC family enzymes convert cytosines in single-stranded DNA to uracils, causing base substitutions and strand breaks. They are induced by cytokines produced during the body's inflammatory response to infections, and they help combat infections through diverse mechanisms. AID is essential for the maturation of antibodies and causes mutations and deletions in antibody genes through somatic hypermutation (SHM) and class-switch recombination (CSR) processes. One member of the APOBEC family, APOBEC1, edits mRNA for a protein involved in lipid transport. Members of the APOBEC3 subfamily in humans (APOBEC3A, APOBEC3B, APOBEC3C, APOBEC3D, APOBEC3F, APOBEC3G, and APOBEC3H) inhibit infections of viruses such as HIV-1, HBV, and HCV, and retrotransposition of endogenous retroelements through mutagenic and nonmutagenic mechanisms. There is emerging consensus that these enzymes can cause mutations in the cellular genome at replication forks or within transcription bubbles depending on the physiological state of the cell and the phase of the cell cycle during which they are expressed. We describe here the state of knowledge about the structures of these enzymes, regulation of their expression, and both the advantageous and deleterious consequences of their expression, including carcinogenesis. We highlight similarities among them and present a holistic view of their regulation and function.
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Affiliation(s)
- Sachini U Siriwardena
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - Kang Chen
- Department of Obstetrics and Gynecology, Wayne State University , Detroit, Michigan 48201, United States
- Mucosal Immunology Studies Team, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland 20892, United States
- Department of Immunology and Microbiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
- Department of Immunology and Microbiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States
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16
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Marx A, Galilee M, Alian A. Zinc enhancement of cytidine deaminase activity highlights a potential allosteric role of loop-3 in regulating APOBEC3 enzymes. Sci Rep 2015; 5:18191. [PMID: 26678087 PMCID: PMC4683357 DOI: 10.1038/srep18191] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/16/2015] [Indexed: 12/25/2022] Open
Abstract
The strong association of APOBEC3 cytidine deaminases with somatic mutations leading to cancers accentuates the importance of their tight intracellular regulation to minimize cellular transformations. We reveal a novel allosteric regulatory mechanism of APOBEC3 enzymes showing that APOBEC3G and APOBEC3A coordination of a secondary zinc ion, reminiscent to ancestral deoxycytidylate deaminases, enhances deamination activity. Zinc binding is pinpointed to loop-3 which whilst highly variable harbors a catalytically essential and spatially conserved asparagine at its N-terminus. We suggest that loop-3 may play a general role in allosterically tuning the activity of zinc-dependent cytidine deaminase family members.
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Affiliation(s)
- Ailie Marx
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Meytal Galilee
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Akram Alian
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
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17
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Nitta T, Ha D, Galvez F, Miyazawa T, Fan H. Human and murine APOBEC3s restrict replication of koala retrovirus by different mechanisms. Retrovirology 2015; 12:68. [PMID: 26253512 PMCID: PMC4528783 DOI: 10.1186/s12977-015-0193-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 07/23/2015] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Koala retrovirus (KoRV) is an endogenous and exogenous retrovirus of koalas that may cause lymphoma. As for many other gammaretroviruses, the KoRV genome can potentially encode an alternate form of Gag protein, glyco-gag. RESULTS In this study, a convenient assay for assessing KoRV infectivity in vitro was employed: the use of DERSE cells (initially developed to search for infectious xenotropic murine leukemia-like viruses). Using infection of DERSE and other human cell lines (HEK293T), no evidence for expression of glyco-gag by KoRV was found, either in expression of glyco-gag protein or changes in infectivity when the putative glyco-gag reading frame was mutated. Since glyco-gag mediates resistance of Moloney murine leukemia virus to the restriction factor APOBEC3, the sensitivity of KoRV (wt or putatively mutant for glyco-gag) to restriction by murine (mA3) or human APOBEC3s was investigated. Both mA3 and hA3G potently inhibited KoRV infectivity. Interestingly, hA3G restriction was accompanied by extensive G → A hypermutation during reverse transcription while mA3 restriction was not. Glyco-gag status did not affect the results. CONCLUSIONS These results indicate that the mechanisms of APOBEC3 restriction of KoRV by hA3G and mA3 differ (deamination dependent vs. independent) and glyco-gag does not play a role in the restriction.
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Affiliation(s)
- Takayuki Nitta
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Department of Biology, Savannah State University, 3219 College St, Savannah, GA, 31404-5254, USA.
| | - Dat Ha
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
| | - Felipe Galvez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
| | - Takayuki Miyazawa
- Laboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
| | - Hung Fan
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
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18
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Harris RS, Dudley JP. APOBECs and virus restriction. Virology 2015; 479-480:131-45. [PMID: 25818029 PMCID: PMC4424171 DOI: 10.1016/j.virol.2015.03.012] [Citation(s) in RCA: 384] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 02/10/2015] [Accepted: 03/04/2015] [Indexed: 12/22/2022]
Abstract
The APOBEC family of single-stranded DNA cytosine deaminases comprises a formidable arm of the vertebrate innate immune system. Pre-vertebrates express a single APOBEC, whereas some mammals produce as many as 11 enzymes. The APOBEC3 subfamily displays both copy number variation and polymorphisms, consistent with ongoing pathogenic pressures. These enzymes restrict the replication of many DNA-based parasites, such as exogenous viruses and endogenous transposable elements. APOBEC1 and activation-induced cytosine deaminase (AID) have specialized functions in RNA editing and antibody gene diversification, respectively, whereas APOBEC2 and APOBEC4 appear to have different functions. Nevertheless, the APOBEC family protects against both periodic viral zoonoses as well as exogenous and endogenous parasite replication. This review highlights viral pathogens that are restricted by APOBEC enzymes, but manage to escape through unique mechanisms. The sensitivity of viruses that lack counterdefense measures highlights the need to develop APOBEC-enabling small molecules as a new class of anti-viral drugs.
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Affiliation(s)
- Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, and Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States.
| | - Jaquelin P Dudley
- Department of Molecular Biosciences, Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, United States.
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19
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Stavrou S, Blouch K, Kotla S, Bass A, Ross SR. Nucleic acid recognition orchestrates the anti-viral response to retroviruses. Cell Host Microbe 2015; 17:478-88. [PMID: 25816774 DOI: 10.1016/j.chom.2015.02.021] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/06/2015] [Accepted: 02/05/2015] [Indexed: 12/21/2022]
Abstract
Intrinsic restriction factors and viral nucleic acid sensors are important for the anti-viral response. Here, we show how upstream sensing of retroviral reverse transcripts integrates with the downstream effector APOBEC3, an IFN-induced cytidine deaminase that introduces lethal mutations during retroviral reverse transcription. Using a murine leukemia virus (MLV) variant with an unstable capsid that induces a strong IFNβ antiviral response, we identify three sensors, IFI203, DDX41, and cGAS, required for MLV nucleic acid recognition. These sensors then signal using the adaptor STING, leading to increased production of IFNβ and other targets downstream of the transcription factor IRF3. Using knockout and mutant mice, we show that APOBEC3 limits the levels of reverse transcripts that trigger cytosolic sensing, and that nucleic acid sensing in vivo increases expression of IFN-regulated restriction factors like APOBEC3 that in turn reduce viral load. These studies underscore the importance of the multiple layers of protection afforded by host factors.
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Affiliation(s)
- Spyridon Stavrou
- Department of Microbiology, Institute for Immunology and Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristin Blouch
- Department of Microbiology, Institute for Immunology and Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Swathi Kotla
- Department of Microbiology, Institute for Immunology and Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Antonia Bass
- Department of Microbiology, Institute for Immunology and Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Susan R Ross
- Department of Microbiology, Institute for Immunology and Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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20
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Antiretroviral restriction factors in mice. Virus Res 2014; 193:130-4. [PMID: 25018022 DOI: 10.1016/j.virusres.2014.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/30/2014] [Accepted: 07/01/2014] [Indexed: 12/31/2022]
Abstract
One of the most exciting areas in contemporary retrovirus research is the discovery of "restriction factors". These are cellular proteins that act after virus entry to inhibit infection by or replication of retroviruses (and other viruses and intracellular pathogens). We briefly discuss here three antiretroviral restriction factors in mice: Fv1, APOBEC3, and tetherin, touching on both biological and molecular aspects of these restriction systems.
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21
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Mouse knockout models for HIV-1 restriction factors. Cell Mol Life Sci 2014; 71:3749-66. [PMID: 24854580 PMCID: PMC4160573 DOI: 10.1007/s00018-014-1646-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/24/2014] [Accepted: 05/05/2014] [Indexed: 12/21/2022]
Abstract
Infection of cells with human immunodeficiency virus 1 (HIV-1) is controlled by restriction factors, host proteins that counteract a variety of steps in the life cycle of this lentivirus. These include SAMHD1, APOBEC3G and tetherin, which block reverse transcription, hypermutate viral DNA and prevent progeny virus release, respectively. These and other HIV-1 restriction factors are conserved and have clear orthologues in the mouse. This review summarises studies in knockout mice lacking HIV-1 restriction factors. In vivo experiments in such animals have not only validated in vitro data obtained from cultured cells, but have also revealed new findings about the biology of these proteins. Indeed, genetic ablation of HIV-1 restriction factors in the mouse has provided evidence that restriction factors control retroviruses and other viruses in vivo and has led to new insights into the mechanisms by which these proteins counteract infection. For example, in vivo experiments in knockout mice demonstrate that virus control exerted by restriction factors can shape adaptive immune responses. Moreover, the availability of animals lacking restriction factors opens the possibility to study the function of these proteins in other contexts such as autoimmunity and cancer. Further in vivo studies of more recently identified HIV-1 restriction factors in gene targeted mice are, therefore, justified.
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Abstract
Cytidine deaminases are enzymes that catalyze the removal of an amino group from cytidine, forming uridine. APOBEC3 (ApolipoproteinB mRNA editing enzyme, catalytic polypeptide like) proteins are cytidine deaminases that deaminate cytidines in polynucleotides (RNA/DNA), resulting in editing of their target substrates. Mammalian APOBEC3 proteins are an important element in cellular defenses against retrovirus replication, and this "restriction" of retroviral infections is partially due to the cytidine deaminase activity of the APOBEC3. The present protocol (Nair et al., 2014) describes the assay to detect the deaminase activity of mouse APOBEC3 protein, which targets cytidines present in TCC or TTC motifs in a single-stranded DNA substrate. In brief, the protein preparation to be assayed is incubated with a fluorophore-labeled oligodeoxynucleotide containing the deamination target motif (radiolabeled oligonucleotide substrates have also been successfully used by other groups). Cytidines in the oligonucleotide are deaminated to uridines; the addition of Uracil DNA Glycosylase (UDG) catalyzes the hydrolysis of the N-glycosylic bond between uracil and sugar, generating an abasic (AB) site in the oligonucleotide. Mild alkali treatment cleaves the substrate oligonucleotide at the AB site; cleaved products are resolved from uncleaved substrate by denaturing polyacrylamide gel electrophoresis and visualized on a fluorescence scanner. The protocol described here is mainly adapted from that described by Iwatani et al. (2006) with modifications. The assay can, of course, be used to detect the activity of other APOBEC3 deaminases targeting DNA substrates, using oligonucleotides containing the cytidine-containing target sequence for the deaminase.
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Affiliation(s)
- Smita Nair
- Center for Cancer Research, National Cancer Institute, Frederick, USA; London School of Hygiene and Tropical Medicine, Faculty of Infectious and Tropical Diseases, London, UK
| | - Alan Rein
- Center for Cancer Research, National Cancer Institute, Frederick, USA
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