1
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Xu B, Sui Q, Hu H, Hu X, Zhou X, Qian C, Li N. SAMHD1 Attenuates Acute Inflammation by Maintaining Mitochondrial Function in Macrophages via Interaction with VDAC1. Int J Mol Sci 2023; 24:ijms24097888. [PMID: 37175593 PMCID: PMC10177872 DOI: 10.3390/ijms24097888] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/15/2023] [Accepted: 04/20/2023] [Indexed: 05/15/2023] Open
Abstract
Over-activation of Toll-like receptor 4 (TLR4) is the key mechanism in Gram-negative bacterial infection-induced sepsis. SAM and HD domain-containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) inhibits multiple viruses, but whether it plays a role during bacterial invasion remains unelucidated. Monocyte-macrophage specific Samhd1 knockout (Samhd1-/-) mice and Samhd1-/- macrophage cell line RAW264.7 were constructed and used as research models to evaluate the role of SAMHD1 in TLR4-activated inflammation. In vivo, LPS-challenged Samhd1-/- mice showed higher serum inflammatory factors, accompanied with more severe inflammation infiltration and lower survival rate. In vitro, Samhd1-/- peritoneal macrophages had more activated TLR4 pathway upon LPS-stimulation, accompanied with mitochondrial depolarization and dysfunction and a higher tendency to be M1-polarized. These results could be rescued by overexpressing full-length wild-type SAMHD1 or its phospho-mimetic T634D mutant into Samhd1-/- RAW264.7 cells, whereas the mutants, dNTP hydrolase-function-deprived H238A and phospho-ablative T634A, did not exert the same effect. Lastly, co-IP and immunofluorescence assays confirmed that SAMHD1 interacted with an outer mitochondrial membrane-localized protein, voltage-dependent anion channel-1 (VDAC1). SAMHD1 inhibits TLR4-induced acute inflammation and M1 polarization of macrophages by interacting with VDAC1 and maintaining mitochondria function, which outlines a novel regulatory mechanism of TLR signaling upon LPS stimulation.
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Affiliation(s)
- Bowen Xu
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
| | - Qianyi Sui
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
| | - Han Hu
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
- Faculty of Anesthesiology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Xiangjia Hu
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
| | - Xuchang Zhou
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
- School of Sport Medicine and Rehabilitation, Beijing Sport University, Beijing 100084, China
| | - Cheng Qian
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
| | - Nan Li
- National Key Laboratory of Immunity & Inflammation, Institute of Immunology, Naval Medical University, Shanghai 200433, China
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2
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Barrett B, Nguyen DH, Xu J, Guo K, Shetty S, Jones ST, Mickens KL, Shepard C, Roers A, Behrendt R, Wu L, Kim B, Santiago ML. SAMHD1 Promotes the Antiretroviral Adaptive Immune Response in Mice Exposed to Lipopolysaccharide. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:444-453. [PMID: 34893529 DOI: 10.4049/jimmunol.2001389] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 11/08/2021] [Indexed: 12/13/2022]
Abstract
SAMHD1 is a potent HIV-1 restriction factor that blocks reverse transcription in monocytes, dendritic cells and resting CD4+ T cells by decreasing intracellular dNTP pools. However, SAMHD1 may diminish innate immune sensing and Ag presentation, resulting in a weaker adaptive immune response. To date, the role of SAMHD1 on antiretroviral immunity remains unclear, as mouse SAMHD1 had no impact on murine retrovirus replication in prior in vivo studies. Here, we show that SAMHD1 significantly inhibits acute Friend retrovirus infection in mice. Pretreatment with LPS, a significant driver of inflammation during HIV-1 infection, further unmasked a role for SAMHD1 in influencing immune responses. LPS treatment in vivo doubled the intracellular dNTP levels in immune compartments of SAMHD1 knockout but not wild-type mice. SAMHD1 knockout mice exhibited higher plasma infectious viremia and proviral DNA loads than wild-type mice at 7 d postinfection (dpi), and proviral loads inversely correlated with a stronger CD8+ T cell response. SAMHD1 deficiency was also associated with weaker NK, CD4+ T and CD8+ T cell responses by 14 dpi and weaker neutralizing Ab responses by 28 dpi. Intriguingly, SAMHD1 influenced these cell-mediated immune (14 dpi) and neutralizing Ab (28 dpi) responses in male but not female mice. Our findings formally demonstrate SAMHD1 as an antiretroviral factor in vivo that could promote adaptive immune responses in a sex-dependent manner. The requirement for LPS to unravel the SAMHD1 immunological phenotype suggests that comorbidities associated with a "leaky" gut barrier may influence the antiviral function of SAMHD1 in vivo.
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Affiliation(s)
- BradleyS Barrett
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - David H Nguyen
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Joella Xu
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA
| | - Kejun Guo
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Shravida Shetty
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Sean T Jones
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO.,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
| | - Kaylee L Mickens
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO.,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
| | - Caitlin Shepard
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA
| | - Axel Roers
- Institute for Immunology, Faculty of Medicine, Technical University Dresden, Dresden, Germany
| | - Rayk Behrendt
- Institute for Immunology, Faculty of Medicine, Technical University Dresden, Dresden, Germany
| | - Li Wu
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA; and
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA.,Center for Drug Discovery, Children's Healthcare of Atlanta, Atlanta, GA
| | - Mario L Santiago
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO; .,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
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3
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Wang C, Meng L, Wang J, Zhang K, Duan S, Ren P, Wei Y, Fu X, Yu B, Wu J, Yu X. Role of Intracellular Distribution of Feline and Bovine SAMHD1 Proteins in Lentiviral Restriction. Virol Sin 2021; 36:981-996. [PMID: 33751400 DOI: 10.1007/s12250-021-00351-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/28/2020] [Indexed: 11/28/2022] Open
Abstract
Human SAMHD1 (hSAM) restricts lentiviruses at the reverse transcription step through its dNTP triphosphohydrolase (dNTPase) activity. Besides humans, several mammalian species such as cats and cows that carry their own lentiviruses also express SAMHD1. However, the intracellular distribution of feline and bovine SAMHD1 (fSAM and bSAM) and its significance in their lentiviral restriction function is not known. Here, we demonstrated that fSAM and bSAM were both predominantly localized to the nucleus and nuclear localization signal (11KRPR14)-deleted fSAM and bSAM relocalized to the cytoplasm. Both cytoplasmic fSAM and bSAM retained the antiviral function against different lentiviruses and cytoplasmic fSAM could restrict Vpx-encoding SIV and HIV-2 more efficiently than its wild-type (WT) protein as cytoplasmic hSAM. Further investigation revealed that cytoplasmic fSAM was resistant to Vpx-induced degradation like cytoplasmic hSAM, while cytoplasmic bSAM was not, but they all demonstrated the same in vitro dNTPase activity and all could interact with Vpx as their WT proteins, indicating that cytoplasmic hSAM and fSAM can suppress more SIV and HIV-2 by being less sensitive to Vpx-mediated degradation. Our results suggested that fSAM- and bSAM-mediated lentiviral restriction does not require their nuclear localization and that fSAM shares more common features with hSAM. These findings may provide insights for the establishment of alternative animal models to study SAMHD1 in vivo.
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Affiliation(s)
- Chu Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,The First Hospital and Institute of Immunology, Jilin University, Changchun, 130012, China
| | - Lina Meng
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jialin Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Kaikai Zhang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Sizhu Duan
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Pengyu Ren
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Yingzhe Wei
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Xinyu Fu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Bin Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jiaxin Wu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
| | - Xianghui Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
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4
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SAMHD1 … and Viral Ways around It. Viruses 2021; 13:v13030395. [PMID: 33801276 PMCID: PMC7999308 DOI: 10.3390/v13030395] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 12/19/2022] Open
Abstract
The SAM and HD domain-containing protein 1 (SAMHD1) is a dNTP triphosphohydrolase that plays a crucial role for a variety of different cellular functions. Besides balancing intracellular dNTP concentrations, facilitating DNA damage repair, and dampening excessive immune responses, SAMHD1 has been shown to act as a major restriction factor against various virus species. In addition to its well-described activity against retroviruses such as HIV-1, SAMHD1 has been identified to reduce the infectivity of different DNA viruses such as the herpesviruses CMV and EBV, the poxvirus VACV, or the hepadnavirus HBV. While some viruses are efficiently restricted by SAMHD1, others have developed evasion mechanisms that antagonize the antiviral activity of SAMHD1. Within this review, we summarize the different cellular functions of SAMHD1 and highlight the countermeasures viruses have evolved to neutralize the restriction factor SAMHD1.
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5
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Retroviral Restriction Factors and Their Viral Targets: Restriction Strategies and Evolutionary Adaptations. Microorganisms 2020; 8:microorganisms8121965. [PMID: 33322320 PMCID: PMC7764263 DOI: 10.3390/microorganisms8121965] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/30/2020] [Accepted: 12/08/2020] [Indexed: 12/17/2022] Open
Abstract
The evolutionary conflict between retroviruses and their vertebrate hosts over millions of years has led to the emergence of cellular innate immune proteins termed restriction factors as well as their viral antagonists. Evidence accumulated in the last two decades has substantially increased our understanding of the elaborate mechanisms utilized by these restriction factors to inhibit retroviral replication, mechanisms that either directly block viral proteins or interfere with the cellular pathways hijacked by the viruses. Analyses of these complex interactions describe patterns of accelerated evolution for these restriction factors as well as the acquisition and evolution of their virus-encoded antagonists. Evidence is also mounting that many restriction factors identified for their inhibition of specific retroviruses have broader antiviral activity against additional retroviruses as well as against other viruses, and that exposure to these multiple virus challenges has shaped their adaptive evolution. In this review, we provide an overview of the restriction factors that interfere with different steps of the retroviral life cycle, describing their mechanisms of action, adaptive evolution, viral targets and the viral antagonists that evolved to counter these factors.
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6
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SAMHD1 Functions and Human Diseases. Viruses 2020; 12:v12040382. [PMID: 32244340 PMCID: PMC7232136 DOI: 10.3390/v12040382] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/12/2022] Open
Abstract
Deoxynucleoside triphosphate (dNTP) molecules are essential for the replication and maintenance of genomic information in both cells and a variety of viral pathogens. While the process of dNTP biosynthesis by cellular enzymes, such as ribonucleotide reductase (RNR) and thymidine kinase (TK), has been extensively investigated, a negative regulatory mechanism of dNTP pools was recently found to involve sterile alpha motif (SAM) domain and histidine-aspartate (HD) domain-containing protein 1, SAMHD1. When active, dNTP triphosphohydrolase activity of SAMHD1 degrades dNTPs into their 2'-deoxynucleoside (dN) and triphosphate subparts, steadily depleting intercellular dNTP pools. The differential expression levels and activation states of SAMHD1 in various cell types contributes to unique dNTP pools that either aid (i.e., dividing T cells) or restrict (i.e., nondividing macrophages) viral replication that consumes cellular dNTPs. Genetic mutations in SAMHD1 induce a rare inflammatory encephalopathy called Aicardi-Goutières syndrome (AGS), which phenotypically resembles viral infection. Recent publications have identified diverse roles for SAMHD1 in double-stranded break repair, genome stability, and the replication stress response through interferon signaling. Finally, a series of SAMHD1 mutations were also reported in various cancer cell types while why SAMHD1 is mutated in these cancer cells remains to investigated. Here, we reviewed a series of studies that have begun illuminating the highly diverse roles of SAMHD1 in virology, immunology, and cancer biology.
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7
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Qin Z, Bonifati S, St Gelais C, Li TW, Kim SH, Antonucci JM, Mahboubi B, Yount JS, Xiong Y, Kim B, Wu L. The dNTPase activity of SAMHD1 is important for its suppression of innate immune responses in differentiated monocytic cells. J Biol Chem 2020; 295:1575-1586. [PMID: 31914403 PMCID: PMC7008377 DOI: 10.1074/jbc.ra119.010360] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/22/2019] [Indexed: 12/18/2022] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphohydrolase (dNTPase) with a nuclear localization signal (NLS). SAMHD1 suppresses innate immune responses to viral infection and inflammatory stimuli by inhibiting the NF-κB and type I interferon (IFN-I) pathways. However, whether the dNTPase activity and nuclear localization of SAMHD1 are required for its suppression of innate immunity remains unknown. Here, we report that the dNTPase activity, but not nuclear localization of SAMHD1, is important for its suppression of innate immune responses in differentiated monocytic cells. We generated monocytic U937 cell lines stably expressing WT SAMHD1 or mutated variants defective in dNTPase activity (HD/RN) or nuclear localization (mNLS). WT SAMHD1 in differentiated U937 cells significantly inhibited lipopolysaccharide-induced expression of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) mRNAs, as well as IFN-α, IFN-β, and TNF-α mRNA levels induced by Sendai virus infection. In contrast, the HD/RN mutant did not exhibit this inhibition in either U937 or THP-1 cells, indicating that the dNTPase activity of SAMHD1 is important for suppressing NF-κB activation. Of note, in lipopolysaccharide-treated or Sendai virus-infected U937 or THP-1 cells, the mNLS variant reduced TNF-α or IFN-β mRNA expression to a similar extent as did WT SAMHD1, suggesting that SAMHD1-mediated inhibition of innate immune responses is independent of SAMHD1's nuclear localization. Moreover, WT and mutant SAMHD1 similarly interacted with key proteins in NF-κB and IFN-I pathways in cells. This study further defines the role and mechanisms of SAMHD1 in suppressing innate immunity.
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Affiliation(s)
- Zhihua Qin
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210; Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Serena Bonifati
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Corine St Gelais
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Tai-Wei Li
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Sun-Hee Kim
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Jenna M Antonucci
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Bijan Mahboubi
- Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, Infectious Diseases Institute, The Ohio State University, Columbus, Ohio 43210
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Li Wu
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210; Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242; Department of Microbial Infection and Immunity, Infectious Diseases Institute, The Ohio State University, Columbus, Ohio 43210.
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8
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McMichael TM, Zhang Y, Kenney AD, Zhang L, Zani A, Lu M, Chemudupati M, Li J, Yount JS. IFITM3 Restricts Human Metapneumovirus Infection. J Infect Dis 2019; 218:1582-1591. [PMID: 29917090 DOI: 10.1093/infdis/jiy361] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/12/2018] [Indexed: 11/12/2022] Open
Abstract
Human metapneumovirus (hMPV) utilizes a bifurcated cellular entry strategy, fusing either with the plasma membrane or, after endocytosis, with the endosome membrane. Whether cellular factors restrict or enhance either entry pathway is largely unknown. We found that the interferon-induced transmembrane protein 3 (IFITM3) inhibits hMPV infection to an extent similar to endocytosis-inhibiting drugs, and an IFITM3 variant that accumulates at the plasma membrane in addition to its endosome localization provided increased virus restriction. Mechanistically, IFITM3 blocks hMPV F protein-mediated membrane fusion, and inhibition of infection was reversed by the membrane destabilizing drug amphotericin B. Conversely, we found that infection by some hMPV strains is enhanced by the endosomal protein toll-like receptor 7 (TLR7), and that IFITM3 retains the ability to restrict hMPV infection even in cells expressing TLR7. Overall, our results identify IFITM3 as an endosomal restriction factor that limits hMPV infection of cells.
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Affiliation(s)
- Temet M McMichael
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Yu Zhang
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio
| | - Adam D Kenney
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Lizhi Zhang
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Ashley Zani
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Mijia Lu
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Mahesh Chemudupati
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Jianrong Li
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio.,Infectious Diseases Institute, The Ohio State University, Columbus, Ohio
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9
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Monit C, Morris ER, Ruis C, Szafran B, Thiltgen G, Tsai MHC, Mitchison NA, Bishop KN, Stoye JP, Taylor IA, Fassati A, Goldstein RA. Positive selection in dNTPase SAMHD1 throughout mammalian evolution. Proc Natl Acad Sci U S A 2019; 116:18647-18654. [PMID: 31451672 PMCID: PMC6744909 DOI: 10.1073/pnas.1908755116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The vertebrate protein SAMHD1 is highly unusual in having roles in cellular metabolic regulation, antiviral restriction, and regulation of innate immunity. Its deoxynucleoside triphosphohydrolase activity regulates cellular dNTP concentration, reducing levels below those required by lentiviruses and other viruses to replicate. To counter this threat, some primate lentiviruses encode accessory proteins that bind SAMHD1 and induce its degradation; in turn, positive diversifying selection has been observed in regions bound by these lentiviral proteins, suggesting that primate SAMHD1 has coevolved to evade these countermeasures. Moreover, deleterious polymorphisms in human SAMHD1 are associated with autoimmune disease linked to uncontrolled DNA synthesis of endogenous retroelements. Little is known about how evolutionary pressures affect these different SAMHD1 functions. Here, we examine the deeper history of these interactions by testing whether evolutionary signatures in SAMHD1 extend to other mammalian groups and exploring the molecular basis of this coevolution. Using codon-based likelihood models, we find positive selection in SAMHD1 within each mammal lineage for which sequence data are available. We observe positive selection at sites clustered around T592, a residue that is phosphorylated to regulate SAMHD1 activity. We verify experimentally that mutations within this cluster affect catalytic rate and lentiviral restriction, suggesting that virus-host coevolution has required adaptations of enzymatic function. Thus, persistent positive selection may have involved the adaptation of SAMHD1 regulation to balance antiviral, metabolic, and innate immunity functions.
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Affiliation(s)
- Christopher Monit
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Elizabeth R Morris
- Macromolecular Structure Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Christopher Ruis
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Bart Szafran
- Retrovirus-Host Interactions Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Grant Thiltgen
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Ming-Han Chloe Tsai
- Retroviral Replication Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - N Avrion Mitchison
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Kate N Bishop
- Retroviral Replication Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Jonathan P Stoye
- Retrovirus-Host Interactions Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Ariberto Fassati
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom;
| | - Richard A Goldstein
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom;
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10
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Kodigepalli KM, Li M, Bonifati S, Panfil AR, Green PL, Liu SL, Wu L. SAMHD1 inhibits epithelial cell transformation in vitro and affects leukemia development in xenograft mice. Cell Cycle 2018; 17:2564-2576. [PMID: 30474474 DOI: 10.1080/15384101.2018.1550955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a mammalian dNTP hydrolase (dNTPase) and functions as a negative regulator in the efficacy of cytarabine treatment of acute myeloid leukemia (AML). We have reported that SAMHD1 knockout (KO) increased the activity of phosphoinositide 3-kinase (PI3K) in AML-derived THP-1 cells and attenuated their ability to form subcutaneous tumors in xenografted immunodeficient mice. However, the functional significance of SAMHD1 in controlling AML leukemogenesis remains unclear. Previous studies show that in vitro transformation of Madin-Darby canine kidney (MDCK) epithelial cells by the Jaagsiekte sheep retrovirus (JSRV) envelope protein requires activation of the PI3K/Akt oncogenic signaling pathway. Using this cell transformation model, we demonstrated that ectopic expression of wild-type human SAMHD1 or a dNTPase-defective SAMHD1 mutant (HD/AA) significantly inhibited MDCK cell transformation, but did not affect cell proliferation. To visualize and quantify THP-1 cell growth and metastasis in xenografted immunodeficient mice, we generated luciferase-expressing stable SAMHD1 KO THP-1 cells and control THP-1 cells, which were injected intravenously into immunodeficient mice. Bioluminescence imaging and quantification analysis of xenografted mice revealed that SAMHD1 KO cell-derived tumors had similar growth and metastatic potential compared with control cells at 35 days post-injection. However, mice xenografted with SAMHD1 KO cells showed greater survival compared with mice injected with control cells. Our data suggest that exogenous SAMHD1 expression suppresses in vitro cell transformation independently of its dNTPase activity, and that endogenous SAMHD1 affects AML tumorigenicity and disease progression in vivo.
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Affiliation(s)
- Karthik M Kodigepalli
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Minghua Li
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Serena Bonifati
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Amanda R Panfil
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Patrick L Green
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA.,b Department of Cancer Biology and Genetics , The Ohio State University , Columbus , OH , USA.,c Comprehensive Cancer Center, The Ohio State University , Columbus , OH , USA
| | - Shan-Lu Liu
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA.,d Department of Microbial Infection and Immunity , The Ohio State University , Columbus , OH , USA
| | - Li Wu
- a Center for Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA.,c Comprehensive Cancer Center, The Ohio State University , Columbus , OH , USA.,d Department of Microbial Infection and Immunity , The Ohio State University , Columbus , OH , USA
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11
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Antonucci JM, Kim SH, St Gelais C, Bonifati S, Li TW, Buzovetsky O, Knecht KM, Duchon AA, Xiong Y, Musier-Forsyth K, Wu L. SAMHD1 Impairs HIV-1 Gene Expression and Negatively Modulates Reactivation of Viral Latency in CD4 + T Cells. J Virol 2018; 92:e00292-18. [PMID: 29793958 PMCID: PMC6052313 DOI: 10.1128/jvi.00292-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/15/2018] [Indexed: 11/20/2022] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) restricts human immunodeficiency virus type 1 (HIV-1) replication in nondividing cells by degrading intracellular deoxynucleoside triphosphates (dNTPs). SAMHD1 is highly expressed in resting CD4+ T cells, which are important for the HIV-1 reservoir and viral latency; however, whether SAMHD1 affects HIV-1 latency is unknown. Recombinant SAMHD1 binds HIV-1 DNA or RNA fragments in vitro, but the function of this binding remains unclear. Here we investigate the effect of SAMHD1 on HIV-1 gene expression and reactivation of viral latency. We found that endogenous SAMHD1 impaired HIV-1 long terminal repeat (LTR) activity in monocytic THP-1 cells and HIV-1 reactivation in latently infected primary CD4+ T cells. Overexpression of wild-type (WT) SAMHD1 suppressed HIV-1 LTR-driven gene expression at a transcriptional level. Tat coexpression abrogated SAMHD1-mediated suppression of HIV-1 LTR-driven luciferase expression. SAMHD1 overexpression also suppressed the LTR activity of human T-cell leukemia virus type 1 (HTLV-1), but not that of murine leukemia virus (MLV), suggesting specific suppression of retroviral LTR-driven gene expression. WT SAMHD1 bound to proviral DNA and impaired reactivation of HIV-1 gene expression in latently infected J-Lat cells. In contrast, a nonphosphorylated mutant (T592A) and a dNTP triphosphohydrolase (dNTPase) inactive mutant (H206D R207N [HD/RN]) of SAMHD1 failed to efficiently suppress HIV-1 LTR-driven gene expression and reactivation of latent virus. Purified recombinant WT SAMHD1, but not the T592A and HD/RN mutants, bound to fragments of the HIV-1 LTR in vitro These findings suggest that SAMHD1-mediated suppression of HIV-1 LTR-driven gene expression potentially regulates viral latency in CD4+ T cells.IMPORTANCE A critical barrier to developing a cure for HIV-1 infection is the long-lived viral reservoir that exists in resting CD4+ T cells, the main targets of HIV-1. The viral reservoir is maintained through a variety of mechanisms, including regulation of the HIV-1 LTR promoter. The host protein SAMHD1 restricts HIV-1 replication in nondividing cells, but its role in HIV-1 latency remains unknown. Here we report a new function of SAMHD1 in regulating HIV-1 latency. We found that SAMHD1 suppressed HIV-1 LTR promoter-driven gene expression and reactivation of viral latency in cell lines and primary CD4+ T cells. Furthermore, SAMHD1 bound to the HIV-1 LTR in vitro and in a latently infected CD4+ T-cell line, suggesting that the binding may negatively modulate reactivation of HIV-1 latency. Our findings indicate a novel role for SAMHD1 in regulating HIV-1 latency, which enhances our understanding of the mechanisms regulating proviral gene expression in CD4+ T cells.
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Affiliation(s)
- Jenna M Antonucci
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - Sun Hee Kim
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Corine St Gelais
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Serena Bonifati
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Tai-Wei Li
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Olga Buzovetsky
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Kirsten M Knecht
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Alice A Duchon
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Karin Musier-Forsyth
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Li Wu
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
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12
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Kodigepalli KM, Bonifati S, Tirumuru N, Wu L. SAMHD1 modulates in vitro proliferation of acute myeloid leukemia-derived THP-1 cells through the PI3K-Akt-p27 axis. Cell Cycle 2018; 17:1124-1137. [PMID: 29911928 DOI: 10.1080/15384101.2018.1480218] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a mammalian dNTP hydrolase that acts as a negative regulator in the efficacy of cytarabine treatment against acute myeloid leukemia (AML). However, the role of SAMHD1 in AML development and progression remains unknown. We have reported that SAMHD1 knockout (KO) in the AML-derived THP-1 cells results in enhanced proliferation and reduced apoptosis, but the underlying mechanisms are unclear. Here we show that SAMHD1 KO in THP-1 cells increased PI3K activity and reduced expression of the tumor suppressor PTEN. Pharmacological inhibition of PI3K activity reduced cell proliferation specifically in SAMHD1 KO cells, suggesting that SAMHD1 KO-induced cell proliferation is mediated via enhanced PI3K signaling. However, PI3K inhibition did not significantly affect SAMHD1 KO-reduced apoptosis, implicating the involvement of additional mechanisms. SAMHD1 KO also led to enhanced phosphorylation of p27 at residue T157 and its mis-localization to the cytoplasm. Inhibition of PI3K activity reversed these effects, indicating that SAMHD1 KO-induced changes in p27 phosphorylation and localization is mediated via PI3K-Akt signaling. While SAMHD1 KO significantly enhanced THP-1 cell migration in vitro, SAMHD1 KO attenuated the ability of THP-1 cells to form subcutaneous tumors in xenografted immunodeficient mice. This effect correlated with significantly increased expression of tumor necrosis factor α (TNF-α) in tumors, which may suggest that TNF-α-mediated inflammation could account for the decreased tumorigenicity in vivo. Our findings implicate that SAMHD1 can regulate AML cell proliferation via modulation of the PI3K-Akt-p27 signaling axis, and that SAMHD1 may affect tumorigenicity by downregulating inflammation.
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Affiliation(s)
- Karthik M Kodigepalli
- a Center of Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA.,b Center for Cardiovascular Research , Nationwide Children's Hospital Research Institute , Columbus , OH , USA
| | - Serena Bonifati
- a Center of Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Nagaraja Tirumuru
- a Center of Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA
| | - Li Wu
- a Center of Retrovirus Research, Department of Veterinary Biosciences , The Ohio State University , Columbus , OH , USA.,c Department of Microbial Infection and Immunity , The Ohio State University , Columbus , OH , USA.,d Comprehensive Cancer Center , The Ohio State University , Columbus , OH , USA
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13
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Schott K, Fuchs NV, Derua R, Mahboubi B, Schnellbächer E, Seifried J, Tondera C, Schmitz H, Shepard C, Brandariz-Nuñez A, Diaz-Griffero F, Reuter A, Kim B, Janssens V, König R. Dephosphorylation of the HIV-1 restriction factor SAMHD1 is mediated by PP2A-B55α holoenzymes during mitotic exit. Nat Commun 2018; 9:2227. [PMID: 29884836 PMCID: PMC5993806 DOI: 10.1038/s41467-018-04671-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 05/15/2018] [Indexed: 12/20/2022] Open
Abstract
SAMHD1 is a critical restriction factor for HIV-1 in non-cycling cells and its antiviral activity is regulated by T592 phosphorylation. Here, we show that SAMHD1 dephosphorylation at T592 is controlled during the cell cycle, occurring during M/G1 transition in proliferating cells. Using several complementary proteomics and biochemical approaches, we identify the phosphatase PP2A-B55α responsible for rendering SAMHD1 antivirally active. SAMHD1 is specifically targeted by PP2A-B55α holoenzymes during mitotic exit, in line with observations that PP2A-B55α is a key mitotic exit phosphatase in mammalian cells. Strikingly, as HeLa or activated primary CD4+ T cells enter the G1 phase, pronounced reduction of RT products is observed upon HIV-1 infection dependent on the presence of dephosphorylated SAMHD1. Moreover, PP2A controls SAMHD1 pT592 level in non-cycling monocyte-derived macrophages (MDMs). Thus, the PP2A-B55α holoenzyme is a key regulator to switch on the antiviral activity of SAMHD1.
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Affiliation(s)
- Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Rita Derua
- Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, 3000, Leuven, Belgium.,Facility for Systems Biology based Mass Spectrometry (SYBIOMA), KU Leuven, 3000, Leuven, Belgium
| | - Bijan Mahboubi
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | | | - Janna Seifried
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Christiane Tondera
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Heike Schmitz
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Caitlin Shepard
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Alberto Brandariz-Nuñez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andreas Reuter
- Division of Allergology, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA.,Department of Pharmacy, Kyung-Hee University, 2447, Seoul, South Korea
| | - Veerle Janssens
- Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, 3000, Leuven, Belgium
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany. .,Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA. .,German Center for Infection Research (DZIF), 63225, Langen, Germany.
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14
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SAMHD1 suppresses innate immune responses to viral infections and inflammatory stimuli by inhibiting the NF-κB and interferon pathways. Proc Natl Acad Sci U S A 2018; 115:E3798-E3807. [PMID: 29610295 DOI: 10.1073/pnas.1801213115] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Sterile alpha motif and HD-domain-containing protein 1 (SAMHD1) blocks replication of retroviruses and certain DNA viruses by reducing the intracellular dNTP pool. SAMHD1 has been suggested to down-regulate IFN and inflammatory responses to viral infections, although the functions and mechanisms of SAMHD1 in modulating innate immunity remain unclear. Here, we show that SAMHD1 suppresses the innate immune responses to viral infections and inflammatory stimuli by inhibiting nuclear factor-κB (NF-κB) activation and type I interferon (IFN-I) induction. Compared with control cells, infection of SAMHD1-silenced human monocytic cells or primary macrophages with Sendai virus (SeV) or HIV-1, or treatment with inflammatory stimuli, induces significantly higher levels of NF-κB activation and IFN-I induction. Exogenous SAMHD1 expression in cells or SAMHD1 reconstitution in knockout cells suppresses NF-κB activation and IFN-I induction by SeV infection or inflammatory stimuli. Mechanistically, SAMHD1 inhibits NF-κB activation by interacting with NF-κB1/2 and reducing phosphorylation of the NF-κB inhibitory protein IκBα. SAMHD1 also interacts with the inhibitor-κB kinase ε (IKKε) and IFN regulatory factor 7 (IRF7), leading to the suppression of the IFN-I induction pathway by reducing IKKε-mediated IRF7 phosphorylation. Interactions of endogenous SAMHD1 with NF-κB and IFN-I pathway proteins were validated in human monocytic cells and primary macrophages. Comparing splenocytes from SAMHD1 knockout and heterozygous mice, we further confirmed SAMHD1-mediated suppression of NF-κB activation, suggesting an evolutionarily conserved property of SAMHD1. Our findings reveal functions of SAMHD1 in down-regulating innate immune responses to viral infections and inflammatory stimuli, highlighting the importance of SAMHD1 in modulating antiviral immunity.
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15
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A Cyclin-Binding Motif in Human SAMHD1 Is Required for Its HIV-1 Restriction, dNTPase Activity, Tetramer Formation, and Efficient Phosphorylation. J Virol 2018; 92:JVI.01787-17. [PMID: 29321329 DOI: 10.1128/jvi.01787-17] [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: 10/12/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) regulates intracellular deoxynucleoside triphosphate (dNTP) levels and functions as a retroviral restriction factor through its dNTP triphosphohydrolase (dNTPase) activity. Human SAMHD1 interacts with cell cycle regulatory proteins cyclin A2, cyclin-dependent kinase 1 (CDK1), and CDK2. This interaction mediates phosphorylation of SAMHD1 at threonine 592 (T592), which negatively regulates HIV-1 restriction. We previously reported that the interaction is mediated, at least in part, through a cyclin-binding motif (RXL, amino acids [aa] 451 to 453). To understand the role of the RXL motif in regulating SAMHD1 activity, we performed structural and functional analyses of RXL mutants and the effect on HIV-1 restriction. We found that the RXL mutation (R451A and L453A, termed RL/AA) disrupted SAMHD1 tetramer formation and abolished its dNTPase activity in vitro and in cells. Compared to wild-type (WT) SAMHD1, the RL/AA mutant failed to restrict HIV-1 infection and had reduced binding to cyclin A2. WT SAMHD1 and RL/AA mutant proteins were degraded by Vpx from HIV-2 but were not spontaneously ubiquitinated in the absence of Vpx. Analysis of proteasomal and autophagy degradation revealed that WT and RL/AA SAMHD1 protein levels were enhanced only when both pathways of degradation were simultaneously inhibited. Our results demonstrate that the RXL motif of human SAMHD1 is required for its HIV-1 restriction, tetramer formation, dNTPase activity, and efficient phosphorylation at T592. These findings identify a new functional domain of SAMHD1 important for its structural integrity, enzyme activity, phosphorylation, and HIV-1 restriction.IMPORTANCE SAMHD1 is the first mammalian dNTPase identified as a restriction factor that inhibits HIV-1 replication by decreasing the intracellular dNTP pool in nondividing cells, although the critical mechanisms regulating SAMHD1 function remain unclear. We previously reported that mutations of a cyclin-binding RXL motif in human SAMHD1 significantly affect protein expression levels, half-life, nuclear localization, and phosphorylation, suggesting an important role of this motif in modulating SAMHD1 functions in cells. To further understand the significance and mechanisms of the RXL motif in regulating SAMHD1 activity, we performed structural and functional analyses of the RXL motif mutation and its effect on HIV-1 restriction. Our results indicate that the RXL motif is critical for tetramer formation, dNTPase activity, and HIV-1 restriction. These findings help us understand SAMHD1 interactions with other host proteins and the mechanisms regulating SAMHD1 structure and functions in cells.
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16
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Buzovetsky O, Tang C, Knecht KM, Antonucci JM, Wu L, Ji X, Xiong Y. The SAM domain of mouse SAMHD1 is critical for its activation and regulation. Nat Commun 2018; 9:411. [PMID: 29379009 PMCID: PMC5788916 DOI: 10.1038/s41467-017-02783-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/28/2017] [Indexed: 11/09/2022] Open
Abstract
Human SAMHD1 (hSAMHD1) is a retroviral restriction factor that blocks HIV-1 infection by depleting the cellular nucleotides required for viral reverse transcription. SAMHD1 is allosterically activated by nucleotides that induce assembly of the active tetramer. Although the catalytic core of hSAMHD1 has been studied extensively, previous structures have not captured the regulatory SAM domain. Here we report the crystal structure of full-length SAMHD1 by capturing mouse SAMHD1 (mSAMHD1) structures in three different nucleotide bound states. Although mSAMHD1 and hSAMHD1 are highly similar in sequence and function, we find that mSAMHD1 possesses a more complex nucleotide-induced activation process, highlighting the regulatory role of the SAM domain. Our results provide insights into the regulation of SAMHD1 activity, thereby facilitating the improvement of HIV mouse models and the development of new therapies for certain cancers and autoimmune diseases.
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Affiliation(s)
- Olga Buzovetsky
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Chenxiang Tang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Kirsten M Knecht
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Jenna M Antonucci
- Center of Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, 43210, USA
| | - Li Wu
- Center of Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, 43210, USA
| | - Xiaoyun Ji
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, 210023, China.
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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17
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Jobe O, Kim J, Tycksen E, Onkar S, Michael NL, Alving CR, Rao M. Human Primary Macrophages Derived In Vitro from Circulating Monocytes Comprise Adherent and Non-Adherent Subsets with Differential Expression of Siglec-1 and CD4 and Permissiveness to HIV-1 Infection. Front Immunol 2017; 8:1352. [PMID: 29123518 PMCID: PMC5662875 DOI: 10.3389/fimmu.2017.01352] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/03/2017] [Indexed: 12/18/2022] Open
Abstract
Macrophages are a major target for human immunodeficiency virus type 1 (HIV-1) infection. However, macrophages are largely heterogeneous and may exhibit differences in permissiveness to HIV-1 infection. This study highlights the interplay of macrophage heterogeneity in HIV-1 pathogenesis. We show that monocyte-derived macrophages (MDMs) could be divided into two distinct subsets: CD14+Siglec-1hiCD4+ (non-adherent MDM) and CD14+Siglec-1LoCD4− (adherent MDM). The CD14+Siglec-1hiCD4+MDM subset represented the smaller proportion in the macrophage pool, and varied among different donors. Fractionation and subsequent exposure of the two MDM subsets to HIV-1 revealed opposite outcomes in terms of HIV-1 capture and infection. Although the CD14+Siglec-1hiCD4+MDM captured significantly more HIV-1, infection was significantly higher in the CD14+Siglec-1LoCD4−MDM subset. Thus, CD14+Siglec-1hiCD4+MDM were less permissive to infection. Depletion of CD14+Siglec-1hiCD4+MDM or a decrease in their percentage, resulted in increased infection of MDM, suggestive of a capacity of these cells to capture and sequester HIV-1 in an environment that hinders its infectivity. Increased expression of innate restriction factors and cytokine genes were observed in the non-adherent CD14+Siglec-1hiCD4+MDM, both before and after HIV-1 infection, compared to the adherent CD14+Siglec-1LoCD4−MDM. We speculate that the differential expression of gene expression profiles in the two macrophage subsets may provide an explanation for the differences observed in HIV-1 infectivity.
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Affiliation(s)
- Ousman Jobe
- U.S. Military HIV Research Program, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States.,Laboratory of Adjuvant and Antigen Research, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Jiae Kim
- U.S. Military HIV Research Program, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States.,Laboratory of Adjuvant and Antigen Research, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Eric Tycksen
- Genome Technology Access Center, Department of Genetics, Washington University in St. Louis, St. Louis, MO, United States
| | - Sayali Onkar
- U.S. Military HIV Research Program, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States.,Laboratory of Adjuvant and Antigen Research, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Nelson L Michael
- Laboratory of Molecular Virology and Pathogenesis, Host Genetics Section, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Carl R Alving
- Laboratory of Adjuvant and Antigen Research, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Mangala Rao
- Laboratory of Adjuvant and Antigen Research, U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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18
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Herold N, Rudd SG, Sanjiv K, Kutzner J, Myrberg IH, Paulin CBJ, Olsen TK, Helleday T, Henter JI, Schaller T. With me or against me: Tumor suppressor and drug resistance activities of SAMHD1. Exp Hematol 2017; 52:32-39. [PMID: 28502830 DOI: 10.1016/j.exphem.2017.05.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 04/29/2017] [Accepted: 05/02/2017] [Indexed: 01/04/2023]
Abstract
Sterile alpha motif and histidine/aspartic acid domain-containing protein 1 (SAMHD1) is a (deoxy)guanosine triphosphate (dGTP/GTP)-activated deoxyribonucleoside triphosphate (dNTP) triphosphohydrolase involved in cellular dNTP homoeostasis. Mutations in SAMHD1 have been associated with the hyperinflammatory disease Aicardi-Goutières syndrome (AGS). SAMHD1 also limits cells' permissiveness to infection with diverse viruses, including human immunodeficiency virus (HIV-1), and controls endogenous retroviruses. Increasing evidence supports the role of SAMHD1 as a tumor suppressor. However, SAMHD1 also can act as a resistance factor to nucleoside-based chemotherapies by hydrolyzing their active triphosphate metabolites, thereby reducing response of various malignancies to these anticancer drugs. Hence, informed cancer therapies must take into account the ambiguous properties of SAMHD1 as both an inhibitor of uncontrolled proliferation and a resistance factor limiting the efficacy of anticancer treatments. Here, we provide evidence that SAMHD1 is a double-edged sword for patients with acute myelogenous leukemia (AML). Our time-dependent analyses of The Cancer Genome Atlas (TCGA) AML cohort indicate that high expression of SAMHD1, even though it critically limits the efficacy of high-dose ara-C therapy, might be associated with more favorable disease progression.
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Affiliation(s)
- Nikolas Herold
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden; Theme of Children's and Women's Health, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden.
| | - Sean G Rudd
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kumar Sanjiv
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Juliane Kutzner
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Ida Hed Myrberg
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Cynthia B J Paulin
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Thale Kristin Olsen
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Helleday
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Jan-Inge Henter
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden; Theme of Children's and Women's Health, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Torsten Schaller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.
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19
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Kodigepalli KM, Li M, Liu SL, Wu L. Exogenous expression of SAMHD1 inhibits proliferation and induces apoptosis in cutaneous T-cell lymphoma-derived HuT78 cells. Cell Cycle 2016; 16:179-188. [PMID: 27929746 DOI: 10.1080/15384101.2016.1261226] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Sterile α motif and HD domain-containing protein 1 (SAMHD1) is a mammalian dNTP hydrolase (dNTPase) that regulates intracellular dNTP balance. We have previously reported that SAMHD1 mRNA and protein levels are significantly downregulated in CD4+ T-cells of patients with cutaneous T-cell lymphoma (CTCL), a disease characterized by infiltration of neoplastic CD4+ T-lymphocytes into the skin. However, functional significance of SAMHD1 in CTCL development and progression remains unknown. Here we investigate the mechanism by which SAMHD1 induces apoptosis in CTCL-derived CD4+ T-cells. We stably expressed exogenous SAMHD1 in the CTCL-derived HuT78 T-cell line containing a very low level of endogenous SAMHD1 protein. We found that low-level exogenous expression of SAMHD1 led to a significant reduction in HuT78 cell growth, proliferation, and colony formation. Exogenous SAMHD1 expression in HuT78 cells also resulted in increased spontaneous and Fas ligand (Fas-L)-induced apoptosis levels via activation of the extrinsic pathway, including caspase-8, -3 and -7. Additionally, increased SAMHD1 significantly reduced the protein and mRNA expression of the short isoform of cFLIP (cFLIPS), an important negative regulator of Fas-L-mediated apoptotic signaling. Our results indicate that exogenous SAMHD1 expression inhibits HuT78 cell growth and proliferation in part by increasing apoptosis. These findings implicate that SAMHD1 acts as an inhibitor in CTCL cell growth, suggesting that downregulation of SAMHD1 expression in neoplastic T-cells can facilitate uncontrolled cell proliferation.
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Affiliation(s)
- Karthik M Kodigepalli
- a Center of Retrovirus Research, Department of Veterinary Biosciences ; The Ohio State University , Columbus , OH , USA
| | - Minghua Li
- a Center of Retrovirus Research, Department of Veterinary Biosciences ; The Ohio State University , Columbus , OH , USA
| | - Shan-Lu Liu
- a Center of Retrovirus Research, Department of Veterinary Biosciences ; The Ohio State University , Columbus , OH , USA
| | - Li Wu
- a Center of Retrovirus Research, Department of Veterinary Biosciences ; The Ohio State University , Columbus , OH , USA.,b Comprehensive Cancer Center, The Ohio State University , Columbus , OH , USA.,c Department of Microbial Infection and Immunity , The Ohio State University , Columbus , OH , USA
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Bloch N, Gläsker S, Sitaram P, Hofmann H, Shepard CN, Schultz ML, Kim B, Landau NR. A Highly Active Isoform of Lentivirus Restriction Factor SAMHD1 in Mouse. J Biol Chem 2016; 292:1068-1080. [PMID: 27920203 DOI: 10.1074/jbc.m116.743740] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/01/2016] [Indexed: 11/06/2022] Open
Abstract
The triphosphohydrolase SAMHD1 (sterile α motif and histidine-aspartate domain-containing protein 1) restricts HIV-1 replication in nondividing myeloid cells by depleting the dNTP pool, preventing reverse transcription. SAMHD1 is also reported to have ribonuclease activity that degrades the virus genomic RNA. Human SAMHD1 is regulated by phosphorylation of its carboxyl terminus at Thr-592, which abrogates its antiviral function yet has only a small effect on its phosphohydrolase activity. In the mouse, SAMHD1 is expressed as two isoforms (ISF1 and ISF2) that differ at the carboxyl terminus due to alternative splicing of the last coding exon. In this study we characterized the biochemical and antiviral properties of the two mouse isoforms of SAMHD1. Both are antiviral in nondividing cells. Mass spectrometry analysis showed that SAMHD1 is phosphorylated at several amino acid residues, one of which (Thr-634) is homologous to Thr-592. Phosphomimetic mutation at Thr-634 of ISF1 ablates its antiviral activity yet has little effect on phosphohydrolase activity in vitro dGTP caused ISF1 to tetramerize, activating its catalytic activity. In contrast, ISF2, which lacks the phosphorylation site, was significantly more active, tetramerized, and was active without added dGTP. Neither isoform nor human SAMHD1 had detectable RNase activity in vitro or affected HIV-1 genomic RNA stability in newly infected cells. These data support a model in which SAMHD1 catalytic activity is regulated through tetramer stabilization by the carboxyl-terminal tail, phosphorylation destabilizing the complexes and inactivating the enzyme. ISF2 may serve to reduce the dNTP pool to very low levels as a means of restricting virus replication.
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Affiliation(s)
- Nicolin Bloch
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Sabine Gläsker
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Poojitha Sitaram
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Henning Hofmann
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Caitlin N Shepard
- the Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322, and
| | - Megan L Schultz
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Baek Kim
- the Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322, and.,the School of Pharmacy, Kyunghee University, Seoul 02447, South Korea
| | - Nathaniel R Landau
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016,
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Antonucci JM, St Gelais C, de Silva S, Yount JS, Tang C, Ji X, Shepard C, Xiong Y, Kim B, Wu L. SAMHD1-mediated HIV-1 restriction in cells does not involve ribonuclease activity. Nat Med 2016; 22:1072-1074. [PMID: 27711056 PMCID: PMC5069697 DOI: 10.1038/nm.4163] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Jenna M Antonucci
- Center for Retrovirus Research, Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
| | - Corine St Gelais
- Center for Retrovirus Research, Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, USA
| | - Suresh de Silva
- Center for Retrovirus Research, Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, USA
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, Ohio, USA
| | - Chenxiang Tang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, USA
| | - Xiaoyun Ji
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, USA
| | - Caitlin Shepard
- Department of Pediatrics, Center for Drug Discovery, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, USA
| | - Baek Kim
- Department of Pediatrics, Center for Drug Discovery, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Li Wu
- Center for Retrovirus Research, Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, USA
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, Ohio, USA
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Bonifati S, Daly MB, St Gelais C, Kim SH, Hollenbaugh JA, Shepard C, Kennedy EM, Kim DH, Schinazi RF, Kim B, Wu L. SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells. Virology 2016; 495:92-100. [PMID: 27183329 DOI: 10.1016/j.virol.2016.05.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 05/03/2016] [Indexed: 01/09/2023]
Abstract
SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G1/G0 phase and reduces apoptosis. These alterations correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection.
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Affiliation(s)
- Serena Bonifati
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Michele B Daly
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Corine St Gelais
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Sun Hee Kim
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Joseph A Hollenbaugh
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Caitlin Shepard
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Edward M Kennedy
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA
| | - Dong-Hyun Kim
- Department of Pharmacy, School of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA; Department of Pharmacy, School of Pharmacy, Kyung-Hee University, Seoul, South Korea.
| | - Li Wu
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA.
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