scholarly journals SAMHD1 Is a Modulator of Nucleos(t)ide Analogues’ Efficacy

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 58
Author(s):  
Ifeanyi Ezeonwumelu ◽  
Marc Castellví ◽  
Eudald Felip ◽  
Maria Pujantell ◽  
Edurne Garcia-Vidal ◽  
...  
Keyword(s):  
Drug Efficacy ◽  
Dntp Pool ◽  
Established Cell Lines ◽  
Promising Target ◽  
Viral Restriction ◽  
Intracellular Dntp ◽  
Wide Range ◽  
Established Cell ◽  
Anti Hiv ◽  
Hiv 1

Nucleos(t)ide analogues are commonly used in the treatment of infectious disease and cancer. SAMHD1 is a deoxyribonucleotide (dNTP) triphosphohydrolase which is involved in the regulation of the intracellular dNTP pool, whose function has been linked to viral restriction, cancer development, and autoimmune disorders. Here, we evaluate SAMHD1 function on the antiviral and antiproliferative efficacy of a wide range of nucleos(t)ide analogues which are currently used to treat infections and cancer. The anti-HIV-1 and cytotoxic activity of compounds was assessed in primary and established cell lines in the presence or absence of SAMHD1. SAMHD1 effectively modified the anti-HIV-1 activity of all the nucleos(t)ide analogues tested, whereas sensitivity to a non-nucleoside inhibitor (nevirapine) or nucleoside phosphonates (cidofovir and tenofovir) was not affected. Interestingly, SAMHD1 could either enhance (gemcitabine, capecitabine, fluorouracil, and floxuridine) or inhibit (Ara-C, fludarabine, cladribine, clofarabine, and nelarabine) the antiviral potency of anticancer analogues, an effect that was not dependent on the specific nucleotide targeted. When cytotoxicity was evaluated, SAMHD1-dependent changes were less evident and were restricted to the increased efficacy of fluorouracil and floxuridine and reduced efficacy of nelarabine and ara-C in the presence of SAMHD1. In summary, our results demonstrate that SAMHD1 modifies the efficacy of a wide variety of nucleoside analogues which are used to treat infections, cancer, and other diseases. In addition, the anti-HIV activity of nucleos(t)ide analogues may represent a more sensitive measure of SAMHD1’s impact on drug efficacy. Thus, modulation of SAMHD1’s function may constitute a promising target for the improvement of multiple therapies.

scholarly journals Novel Human Immunodeficiency Virus (HIV) Inhibitors That Have a Dual Mode of Anti-HIV Action

2003 ◽  
Vol 47 (10) ◽  
pp. 3109-3116 ◽  
Author(s):  
Miguel Stevens ◽  
Christophe Pannecouque ◽  
Erik De Clercq ◽  
Jan Balzarini
Keyword(s):  
Human Immunodeficiency Virus ◽  
Protein Expression ◽  
Viral Protein ◽  
Green Fluorescence Protein Expression ◽  
Wide Range ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Anti Hiv ◽  
Hiv 1

ABSTRACT We have found that novel pyridine oxide derivatives are inhibitors of a wide range of human immunodeficiency virus (HIV) type 1 (HIV-1) and HIV-2 strains in CEM cell cultures. Some of the compounds showed inhibitory activities against recombinant HIV-1 reverse transcriptase (RT), whereas others were totally inactive against this viral protein in vitro. Partial retention of anti-HIV-1 activity against virus strains that contain a variety of mutations characteristic of those for resistance to nonnucleoside RT inhibitors and a lack of inhibitory activity against recombinant HIV-2 RT suggested that these pyridine oxide derivatives possess a mode of antiviral action independent from HIV RT inhibition. Time-of-addition experiments revealed that these pyridine oxide derivatives interact at a postintegration step in the replication cycle of HIV. Furthermore, it was shown that these compounds are active not only in acutely HIV-1-infected cells but also in chronically HIV-infected cells. A dose-dependent inhibition of virus particle release and viral protein expression was observed upon exposure to the pyridine oxide derivatives. Finally, inhibition of HIV-1 long terminal repeat-mediated green fluorescence protein expression in quantitative transactivation bioassays indicated that the additional target of action of the pyridine oxide derivatives may be located at the level of HIV gene expression.

scholarly journals Novel inhibitors of human immunodeficiency virus type 2 infectivity

2014 ◽  
Vol 95 (12) ◽  
pp. 2778-2783 ◽  
Author(s):  
Lauren B. Beach ◽  
Jonathan M. Rawson ◽  
Baek Kim ◽  
Steven E. Patterson ◽  
Louis M. Mansky
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Dntp Pool ◽  
Novel Drugs ◽  
Immunodeficiency Virus ◽  
Anti Hiv ◽  
Hiv 1

Human immunodeficiency virus type 2 (HIV-2) infects about two million people worldwide. HIV-2 has fewer treatment options than HIV-1, yet may evolve drug resistance more quickly. We have analysed several novel drugs for anti-HIV-2 activity. It was observed that 5-azacytidine, clofarabine, gemcitabine and resveratrol have potent anti-HIV-2 activity. The EC50 values for 5-azacytidine, clofarabine and resveratrol were found to be significantly lower with HIV-2 than with HIV-1. A time-of-addition assay was used to analyse the ability of these drugs to interfere with HIV-2 replication. Reverse transcription was the likely target for antiretroviral activity. Taken together, several novel drugs have been discovered to have activity against HIV-2. Based upon their known activities, these drugs may elicit enhanced HIV-2 mutagenesis and therefore be useful for inducing HIV-2 lethal mutagenesis. In addition, the data are consistent with HIV-2 reverse transcriptase being more sensitive than HIV-1 reverse transcriptase to dNTP pool alterations.

scholarly journals Role of MxB in Alpha Interferon-Mediated Inhibition of HIV-1 Infection

2018 ◽  
Vol 92 (17) ◽  
Author(s):  
Bin Xu ◽  
Qinghua Pan ◽  
Chen Liang
Keyword(s):  
G Protein ◽  
Transmembrane Protein ◽  
Alpha Interferon ◽  
Wild Type Virus ◽  
Target Cells ◽  
Type I ◽  
Wide Range ◽  
Anti Hiv ◽  
Hiv 1

ABSTRACTType I interferon inhibits viruses through inducing the expression of antiviral proteins, including the myxovirus resistance (Mx) proteins. Compared to the human MxA protein, which inhibits a wide range of viruses, the MxB protein has been reported to specifically inhibit primate lentiviruses, including HIV-1, and herpesviruses. Further, the role of endogenous MxB in alpha interferon-mediated inhibition of HIV-1 infection was questioned by a recent study showing that MxB knockout did not increase the level of infection by HIV-1 which carried the G protein of vesicular stomatitis virus (VSV), allowing infection of CD4-negative HT1080 cells. In order to further examine the anti-HIV-1 activity of endogenous MxB, we have used CRISPR/Cas9 to deplete MxB in different cell lines and observed a substantial restoration of HIV-1 infection in the presence of alpha interferon treatment. However, this rescue effect of MxB knockout became much less pronounced when infection was performed with HIV-1 carrying the VSV G protein. Interestingly, a CRISPR/Cas9 knockout screen of alpha interferon-stimulated genes in U87-MG cells revealed that the genes for interferon-induced transmembrane protein 2 (IFITM2) and IFITM3 inhibited VSV G-pseudotyped HIV-1 much more strongly than the rest of the genes tested, including the gene for MxB. Therefore, our results demonstrate the importance of MxB in alpha interferon-mediated inhibition of HIV-1 infection, which, however, can be underestimated if infection is performed with VSV G protein-pseudotyped HIV-1, due to the high sensitivity of VSV G-mediated infection to inhibition by IFITM proteins.IMPORTANCEThe results of this study reconcile the controversial reports regarding the anti-HIV-1 function of alpha interferon-induced MxB protein. In addition to the different cell types that may have contributed to the different observations, our data also suggest that VSV G protein-pseudotyped HIV-1 is much less inhibited by alpha interferon-induced MxB than HIV-1 itself is. Our results clearly demonstrate an important contribution of MxB to alpha interferon-mediated inhibition of HIV-1 in CD4+T cells, which calls for using HIV-1 target cells and wild-type virus to test the relevance of the anti-HIV-1 activity of endogenous MxB and other restriction factors.

scholarly journals Pharmacological Modulation of SAMHD1 Activity by CDK4/6 Inhibitors Improves Anticancer Therapy

Cancers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 713 ◽  
Author(s):  
Marc Castellví ◽  
Eudald Felip ◽  
Ifeanyi Ezeonwumelu ◽  
Roger Badia ◽  
Edurne Garcia-Vidal ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Anticancer Drug ◽  
Cell Cycle Progression ◽  
Drug Efficacy ◽  
Nucleotide Analogs ◽  
Central Process ◽  
Dntp Pool ◽  
Pharmacological Modulation ◽  
Intracellular Dntp ◽  
Samhd1 Expression

Sterile alpha motif and histidine-aspartic acid domain-containing protein 1 (SAMHD1) is a dNTP triphosphohydrolase involved in the regulation of the intracellular dNTP pool, linked to viral restriction, cancer development and autoimmune disorders. SAMHD1 function is regulated by phosphorylation through a mechanism controlled by cyclin-dependent kinases and tightly linked to cell cycle progression. Recently, SAMHD1 has been shown to decrease the efficacy of nucleotide analogs used as chemotherapeutic drugs. Here, we demonstrate that SAMHD1 can enhance or decrease the efficacy of various classes of anticancer drug, including nucleotide analogues, but also anti-folate drugs and CDK inhibitors. Importantly, we show that selective CDK4/6 inhibitors are pharmacological activators of SAMHD1 that act by inhibiting its inactivation by phosphorylation. Combinations of a CDK4/6 inhibitor with nucleoside or folate antimetabolites potently enhanced drug efficacy, resulting in highly synergic drug combinations (CI < 0.04). Mechanistic analyses reveal that cell cycle-controlled modulation of SAMHD1 function is the central process explaining changes in anticancer drug efficacy, therefore providing functional proof of the potential of CDK4/6 inhibitors as a new class of adjuvants to boost chemotherapeutic regimens. The evaluation of SAMHD1 expression in cancer tissues allowed for the identification of cancer types that would benefit from the pharmacological modulation of SAMHD1 function. In conclusion, these results indicate that the modulation of SAMHD1 function may represent a promising strategy for the improvement of current antimetabolite-based treatments.

scholarly journals p21 Restricts HIV-1 in Monocyte-Derived Dendritic Cells through the Reduction of Deoxynucleoside Triphosphate Biosynthesis and Regulation of SAMHD1 Antiviral Activity

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Jose Carlos Valle-Casuso ◽  
Awatef Allouch ◽  
Annie David ◽  
Gina M. Lenzi ◽  
Lydia Studdard ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dendritic Cells ◽  
Antiviral Activity ◽  
Immune Responses ◽  
Reverse Transcription ◽  
Kinase Inhibitor ◽  
Cell Model ◽  
Dntp Pool ◽  
Intracellular Dntp ◽  
Hiv 1

ABSTRACT HIV-1 infection of noncycling cells, such as dendritic cells (DCs), is impaired due to limited availability of deoxynucleoside triphosphates (dNTPs), which are needed for HIV-1 reverse transcription. The levels of dNTPs are tightly regulated during the cell cycle and depend on the balance between dNTP biosynthesis and degradation. SAMHD1 potently blocks HIV-1 replication in DCs, although the underlying mechanism is still unclear. SAMHD1 has been reported to be able to degrade dNTPs and viral nucleic acids, which may both hamper HIV-1 reverse transcription. The relative contribution of these activities may differ in cycling and noncycling cells. Here, we show that inhibition of HIV-1 replication in monocyte-derived DCs (MDDCs) is associated with an increased expression of p21cip1/waf, a cell cycle regulator that is involved in the differentiation and maturation of DCs. Induction of p21 in MDDCs decreases the pool of dNTPs and increases the antiviral active isoform of SAMHD1. Although both processes are complementary in inhibiting HIV-1 replication, the antiviral activity of SAMHD1 in our primary cell model appears to be, at least partially, independent of its dNTPase activity. The reduction in the pool of dNTPs in MDDCs appears rather mostly due to a p21-mediated suppression of several enzymes involved in dNTP synthesis (i.e., RNR2, TYMS, and TK-1). These results are important to better understand the interplay between HIV-1 and DCs and may inform the design of new therapeutic approaches to decrease viral dissemination and improve immune responses against HIV-1. IMPORTANCE DCs play a key role in the induction of immune responses against HIV. However, HIV has evolved ways to exploit these cells, facilitating immune evasion and virus dissemination. We have found that the expression of p21, a cyclin-dependent kinase inhibitor involved in cell cycle regulation and monocyte differentiation and maturation, potentially can contribute to the inhibition of HIV-1 replication in monocyte-derived DCs through multiple mechanisms. p21 decreased the size of the intracellular dNTP pool. In parallel, p21 prevented SAMHD1 phosphorylation and promoted SAMHD1 dNTPase-independent antiviral activity. Thus, induction of p21 resulted in conditions that allowed the effective inhibition of HIV-1 replication through complementary mechanisms. Overall, p21 appears to be a key regulator of HIV infection in myeloid cells.

scholarly journals Pro-515 of the dynamin-like GTPase MxB contributes to HIV-1 inhibition by regulating MxB oligomerization and binding to HIV-1 capsid

2020 ◽  
Vol 295 (19) ◽  
pp. 6447-6456 ◽  
Author(s):  
Fengwen Xu ◽  
Fei Zhao ◽  
Xiaoxiao Zhao ◽  
Di Zhang ◽  
Xiaoman Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nuclear Localization ◽  
Nuclear Export ◽  
Nuclear Export Signal ◽  
Wide Range ◽  
Localization Signal ◽  
Resistance Protein ◽  
Anti Hiv ◽  
Export Signal ◽  
Hiv 1

Interferon-regulated myxovirus resistance protein B (MxB) is an interferon-induced GTPase belonging to the dynamin superfamily. It inhibits infection with a wide range of different viruses, including HIV-1, by impairing viral DNA entry into the nucleus. Unlike the related antiviral GTPase MxA, MxB possesses an N-terminal region that contains a nuclear localization signal and is crucial for inhibiting HIV-1. Because MxB previously has been shown to reside in both the nuclear envelope and the cytoplasm, here we used bioinformatics and biochemical approaches to identify a nuclear export signal (NES) responsible for MxB's cytoplasmic location. Using the online computational tool LocNES (Locating Nuclear Export Signals or NESs), we identified five putative NES candidates in MxB and investigated whether their deletion caused nuclear localization of MxB. Our results revealed that none of the five deletion variants relocates to the nucleus, suggesting that these five predicted NES sequences do not confer NES activity. Interestingly, deletion of one sequence, encompassing amino acids 505–527, abrogated the anti-HIV-1 activity of MxB. Further mutation experiments disclosed that amino acids 515–519, and Pro-515 in particular, regulate MxB oligomerization and its binding to HIV-1 capsid, thereby playing an important role in MxB-mediated restriction of HIV-1 infection. In summary, our results indicate that none of the five predicted NES sequences in MxB appears to be required for its nuclear export. Our findings also reveal several residues in MxB, including Pro-515, critical for its oligomerization and anti-HIV-1 function.

scholarly journals Vpx overcomes a SAMHD1-independent block to HIV reverse transcription that is specific to resting CD4 T cells

2017 ◽  
Vol 114 (10) ◽  
pp. 2729-2734 ◽  
Author(s):  
Hanna-Mari Baldauf ◽  
Lena Stegmann ◽  
Sarah-Marie Schwarz ◽  
Ina Ambiel ◽  
Maud Trotard ◽  
...  
Keyword(s):  
T Cells ◽  
Reverse Transcription ◽  
Cd4 T Cells ◽  
Single Amino Acid ◽  
Sooty Mangabey ◽  
Dntp Pool ◽  
Sam Domain ◽  
Virion Incorporation ◽  
Intracellular Dntp ◽  
Hiv 1

Early after entry into monocytes, macrophages, dendritic cells, and resting CD4 T cells, HIV encounters a block, limiting reverse transcription (RT) of the incoming viral RNA genome. In this context, dNTP triphosphohydrolase SAM domain and HD domain-containing protein 1 (SAMHD1) has been identified as a restriction factor, lowering the concentration of dNTP substrates to limit RT. The accessory lentiviral protein X (Vpx) proteins from the major simian immunodeficiency virus of rhesus macaque, sooty mangabey, and HIV-2 (SIVsmm/SIVmac/HIV-2) lineage packaged into virions target SAMHD1 for proteasomal degradation, increase intracellular dNTP pools, and facilitate HIV cDNA synthesis. We find that virion-packaged Vpx proteins from a second SIV lineage, SIV of red-capped mangabeys or mandrills (SIVrcm/mnd-2), increased HIV infection in resting CD4 T cells, but not in macrophages, and, unexpectedly, acted in the absence of SAMHD1 degradation, dNTP pool elevation, or changes in SAMHD1 phosphorylation. Vpx rcm/mnd-2 virion incorporation resulted in a dramatic increase of HIV-1 RT intermediates and viral cDNA in infected resting CD4 T cells. These analyses also revealed a barrier limiting HIV-1 infection of resting CD4 T cells at the level of nuclear import. Single amino acid changes in the SAMHD1-degrading Vpx mac239 allowed it to enhance early postentry steps in a Vpx rcm/mnd-2–like fashion. Moreover, Vpx enhanced HIV-1 infection of SAMHD1-deficient resting CD4 T cells of a patient with Aicardi-Goutières syndrome. These results indicate that Vpx, in addition to SAMHD1, overcomes a previously unappreciated restriction for lentiviruses at the level of RT that acts independently of dNTP concentrations and is specific to resting CD4 T cells.

Anticardiolipin Antibodies Are Elevated in HIV-1 Infected Haemophiliacs but Do Not Predict for Disease Progression

1989 ◽  
Vol 61 (01) ◽  
pp. 081-085 ◽  
Author(s):  
Simon Panzer ◽  
Christoph Stain ◽  
Hubert Hartl ◽  
Robert Dudczak ◽  
Klaus Lechner
Keyword(s):  
Normal Values ◽  
Anticardiolipin Antibodies ◽  
Haemophilia A ◽  
Serum Samples ◽  
Factor Viii Concentrates ◽  
Patient Groups ◽  
Anti Hiv ◽  
Hiv 1 ◽  
Cd4 Lymphocytes

SummaryLevels of anticardiolipin antibodies (ACA) were measured in 55 patients with haemophilia A in serum samples obtained in 1983 and in 1987. Twenty-one patients were negative for anti HIV-1 antibodies in 1983 and remained negative in 1987; 34 patients had anti HIV-1 antibodies in 1983; 17 of these latter patients remained asymptomatic, whereas 17 patients developed ARC or AIDS during the 4 years follow-up. Thirteen anti HIV-1 negative patients had elevated ACA levels in 1983; subsequently, a significant decrease was observed in all these subjects (p <0.001). All anti HIV-1 positive patients had elevated ACA levels in 1983; normal values were found in 9 patients in 1987. Yet, these changes were not significant (p >0.05). ACA levels were significantly higher in HIV-1 infected patients than in those without anti HIV-1 antibodies (p <0.05). There was no difference of ACA levels between the two anti HIV-1 positive patient groups, be it in 1983 or be it in 1987 (p >0.05). There was no correlation of ACA levels with serum IgG concentrations, CD4+ lymphocytes, or the consumption of factor VIII concentrates.

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