title: Anti-HIV host factor SAMHD1 regulates viral sensitivity to nucleoside reverse transcriptase inhibitors via modulation of cellular deoxyribonucleoside triphosphate (dNTP) levels.
abstract: Newly identified anti-HIV host factor, SAMHD1, restricts replication of lentiviruses such as HIV-1, HIV-2, and simian immunodeficiency virus in macrophages by enzymatically hydrolyzing and depleting cellular dNTPs, which are the substrates of viral DNA polymerases. HIV-2 and some simian immunodeficiency viruses express viral protein X (VPX), which counteracts SAMHD1 and elevates cellular dNTPs, enhancing viral replication in macrophages. Because nucleoside reverse transcriptase inhibitors (NRTIs), the most commonly used anti-HIV drugs, compete against cellular dNTPs for incorporation into proviral DNA, we tested whether SAMHD1 directly affects the efficacy of NRTIs in inhibiting HIV-1. We found that reduction of SAMHD1 levels with the use of virus-like particles expressing Vpx- and SAMHD1-specific shRNA subsequently elevates cellular dNTPs and significantly decreases HIV-1 sensitivity to various NRTIs in macrophages. However, virus-like particles +Vpx treatment of activated CD4(+) T cells only minimally reduced NRTI efficacy. Furthermore, with the use of HPLC, we could not detect SAMHD1-mediated hydrolysis of NRTI-triphosphates, verifying that the reduced sensitivity of HIV-1 to NRTIs upon SAMHD1 degradation is most likely caused by the elevation in cellular dNTPs.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Amie
authors.forename: Michele B
authors.initials: MB
authors.lastname: Daly
authors.forename: Erin
authors.initials: E
authors.lastname: Noble
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Schinazi
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bambara
authors.forename: Baek
authors.initials: B
authors.lastname: Kim
mesh_terms: D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D002478:Cells, Cultured; D003853:Deoxyribonucleosides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D054884:Host-Pathogen Interactions; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000821:virology; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019829:Nevirapine / Q000494:pharmacology; D034622:RNA Interference; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D000076106:SAM Domain and HD Domain-Containing Protein 1; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics / Q000502:physiology; D014771:Virion / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects; D015215:Zidovudine / Q000494:pharmacology
chemical_list: D003853:Deoxyribonucleosides; D018894:Reverse Transcriptase Inhibitors; D054334:Viral Regulatory and Accessory Proteins; D015215:Zidovudine; D019829:Nevirapine; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human; D020559:Monomeric GTP-Binding Proteins
keywords: DNA Polymerase; DNA Replication; HIV-1; Macrophages; Nucleoside Nucleotide Analogs