Naphthalene Diimide-Tetraazacycloalkane Conjugates Are G-Quadruplex-Based HIV-1 Inhibitors with a Dual Mode of Action.

Human immunodeficiency virus 1 (HIV-1) therapeutic regimens consist of three or more drugs targeting different steps of the viral life cycle to limit the emergence of viral resistance. In line with the multitargeting strategy, here we conjugated a naphthalene diimide (NDI) moiety with a tetraazacycloalkane to obtain novel naphthalene diimide (NDI)-tetraazacycloalkane conjugates. The NDI inhibits the HIV-1 promoter activity by binding to LTR G-quadruplexes, and the tetraazacycloalkane mimics AMD3100, which blocks HIV entry into cells by interfering with the CXCR4 coreceptor.

CD38 regulates ovarian function and fecundity via NAD metabolism.

Mammalian female reproductive lifespan is typically significantly shorter than life expectancy and is associated with a decrease in ovarian NAD+ levels. However, the mechanisms underlying this loss of ovarian NAD+ are unclear. Here, we show that CD38, an NAD+ consuming enzyme, is expressed in the ovarian extrafollicular space, primarily in immune cells, and its levels increase with reproductive age.

Fused in Liposarcoma Protein, a New Player in the Regulation of HIV-1 Transcription, Binds to Known and Newly Identified LTR G-Quadruplexes.

HIV-1 integrated long terminal repeat (LTR) promoter activity is modulated by folding of its G-rich region into non-canonical nucleic acids structures, such as G-quadruplexes (G4s), and their interaction with cellular proteins. Here, by a combined pull-down/mass spectrometry/Western-blot approach, we identified the fused in liposarcoma (FUS) protein and found it to preferentially bind and stabilize the least stable and bulged LTR G4, especially in the cell environment. The outcome of this interaction is the down-regulation of viral transcription, as assessed in a reporter assay with LTR G4 mutants in FUS-silencing conditions.

Targeting Conserved Sequences Circumvents the Evolution of Resistance in a Viral Gene Drive against Human Cytomegalovirus.

Gene drives are genetic systems designed to efficiently spread a modification through a population. They have been designed almost exclusively in eukaryotic species, especially in insects. We recently developed a CRISPR-based gene drive system in herpesviruses that relies on similar mechanisms and could efficiently spread into a population of wild-type viruses.

Antiviral Activity of the G-Quadruplex Ligand TMPyP4 against Herpes Simplex Virus-1.

The herpes simplex virus 1 (HSV-1) genome is extremely rich in guanine tracts that fold into G-quadruplexes (G4s), nucleic acid secondary structures implicated in key biological functions. Viral G4s were visualized in HSV-1 infected cells, with massive virus cycle-dependent G4-formation peaking during viral DNA replication. Small molecules that specifically interact with G4s have been shown to inhibit HSV-1 DNA replication.

NAD metabolism and its roles in cellular processes during ageing.

Nicotinamide adenine dinucleotide (NAD) is a coenzyme for redox reactions, making it central to energy metabolism. NAD is also an essential cofactor for non-redox NAD-dependent enzymes, including sirtuins, CD38 and poly(ADP-ribose) polymerases. NAD can directly and indirectly influence many key cellular functions, including metabolic pathways, DNA repair, chromatin remodelling, cellular senescence and immune cell function.

Senescent cells promote tissue NAD decline during ageing via the activation of CD38 macrophages.

Declining tissue nicotinamide adenine dinucleotide (NAD) levels are linked to ageing and its associated diseases. However, the mechanism for this decline is unclear. Here, we show that pro-inflammatory M1-like macrophages, but not naive or M2 macrophages, accumulate in metabolic tissues, including visceral white adipose tissue and liver, during ageing and acute responses to inflammation.

FOXO1 promotes HIV latency by suppressing ER stress in T cells.

Quiescence is a hallmark of CD4 T cells latently infected with human immunodeficiency virus 1 (HIV-1). While reversing this quiescence is an effective approach to reactivate latent HIV from T cells in culture, it can cause deleterious cytokine dysregulation in patients. As a key regulator of T-cell quiescence, FOXO1 promotes latency and suppresses productive HIV infection.

Stable and Conserved G-Quadruplexes in the Long Terminal Repeat Promoter of Retroviruses.

Retroviruses infect almost all vertebrates, from humans to domestic and farm animals, from primates to wild animals, where they cause severe diseases, including immunodeficiencies, neurological disorders, and cancer. Nonhuman retroviruses have also been recently associated with human diseases. To date, no effective treatments are available; therefore, finding retrovirus-specific therapeutic targets is becoming an impelling issue.

G-quadruplex forming sequences in the genome of all known human viruses: A comprehensive guide.

G-quadruplexes are non-canonical nucleic-acid structures that control transcription, replication, and recombination in organisms. G-quadruplexes are present in eukaryotes, prokaryotes, and viruses. In the latter, mounting evidence indicates their key biological activity.

Mapping and characterization of G-quadruplexes in Mycobacterium tuberculosis gene promoter regions.

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), one of the top 10 causes of death worldwide in 2015. The recent emergence of strains resistant to all current drugs urges the development of compounds with new mechanisms of action. G-quadruplexes are nucleic acids secondary structures that may form in G-rich regions to epigenetically regulate cellular functions.

A core extended naphtalene diimide G-quadruplex ligand potently inhibits herpes simplex virus 1 replication.

G-quadruplexes (G4s) are nucleic acids secondary structures, epigenetic regulators in cells and viruses. In herpes simplex virus 1 (HSV-1)-infected cells, G4s are massively present during viral replication. We here aimed at investigating the possibility to target the HSV-1 G4s by a core extended naphtalene diimide (c-exNDI) G4 ligand.

Conserved presence of G-quadruplex forming sequences in the Long Terminal Repeat Promoter of Lentiviruses.

G-quadruplexes (G4s) are secondary structures of nucleic acids that epigenetically regulate cellular processes. In the human immunodeficiency lentivirus 1 (HIV-1), dynamic G4s are located in the unique viral LTR promoter. Folding of HIV-1 LTR G4s inhibits viral transcription; stabilization by G4 ligands intensifies this effect.

The cellular protein hnRNP A2/B1 enhances HIV-1 transcription by unfolding LTR promoter G-quadruplexes.

G-quadruplexes are four-stranded conformations of nucleic acids that act as cellular epigenetic regulators. A dynamic G-quadruplex forming region in the HIV-1 LTR promoter represses HIV-1 transcription when in the folded conformation. This activity is enhanced by nucleolin, which induces and stabilizes the HIV-1 LTR G-quadruplexes.

Visualization of DNA G-quadruplexes in herpes simplex virus 1-infected cells.

We have previously shown that clusters of guanine quadruplex (G4) structures can form in the human herpes simplex-1 (HSV-1) genome. Here we used immunofluorescence and immune-electron microscopy with a G4-specific monoclonal antibody to visualize G4 structures in HSV-1 infected cells. We found that G4 formation and localization within the cells was virus cycle dependent: viral G4s peaked at the time of viral DNA replication in the cell nucleus, moved to the nuclear membrane at the time of virus nuclear egress and were later found in HSV-1 immature virions released from the cell nucleus.

Targeting of RET oncogene by naphthalene diimide-mediated gene promoter G-quadruplex stabilization exerts anti-tumor activity in oncogene-addicted human medullary thyroid cancer.

Medullary thyroid cancer (MTC) relies on the aberrant activation of RET proto-oncogene. Though targeted approaches (i.e.

Structure and possible function of a G-quadruplex in the long terminal repeat of the proviral HIV-1 genome.

The long terminal repeat (LTR) of the proviral human immunodeficiency virus (HIV)-1 genome is integral to virus transcription and host cell infection. The guanine-rich U3 region within the LTR promoter, previously shown to form G-quadruplex structures, represents an attractive target to inhibit HIV transcription and replication. In this work, we report the structure of a biologically relevant G-quadruplex within the LTR promoter region of HIV-1.

The G-quadruplex-forming aptamer AS1411 potently inhibits HIV-1 attachment to the host cell.

AS1411 is a G-rich aptamer that forms a stable G-quadruplex structure and displays antineoplastic properties both in vitro and in vivo. This oligonucleotide has undergone phase 2 clinical trials. The major molecular target of AS1411 is nucleolin (NCL), a multifunctional nucleolar protein also present in the cell membrane where it selectively mediates the binding and uptake of AS1411.

Synthesis, Binding and Antiviral Properties of Potent Core-Extended Naphthalene Diimides Targeting the HIV-1 Long Terminal Repeat Promoter G-Quadruplexes.

We have previously reported that stabilization of the G-quadruplex structures in the HIV-1 long terminal repeat (LTR) promoter suppresses viral transcription. Here we sought to develop new G-quadruplex ligands to be exploited as antiviral compounds by enhancing binding toward the viral G-quadruplex structures. We synthesized naphthalene diimide derivatives with a lateral expansion of the aromatic core.

Nucleolin stabilizes G-quadruplex structures folded by the LTR promoter and silences HIV-1 viral transcription.

Folding of the LTR promoter into dynamic G-quadruplex conformations has been shown to suppress its transcriptional activity in HIV-1. Here we sought to identify the proteins that control the folding of this region of proviral genome by inducing/stabilizing G-quadruplex structures. The implementation of electrophorethic mobility shift assay and pull-down experiments coupled with mass spectrometric analysis revealed that the cellular protein nucleolin is able to specifically recognize G-quadruplex structures present in the LTR promoter.

The Herpes Simplex Virus-1 genome contains multiple clusters of repeated G-quadruplex: Implications for the antiviral activity of a G-quadruplex ligand.

Guanine-rich nucleic acids can fold into G-quadruplexes, secondary structures implicated in important regulatory functions at the genomic level in humans, prokaryotes and viruses. The remarkably high guanine content of the Herpes Simplex Virus-1 (HSV-1) genome prompted us to investigate both the presence of G-quadruplex forming sequences in the viral genome and the possibility to target them with G-quadruplex ligands to obtain anti-HSV-1 effects with a novel mechanism of action. Using biophysical, molecular biology and antiviral assays, we showed that the HSV-1 genome displays multiple clusters of repeated sequences that form very stable G-quadruplexes.

Anti-HIV-1 activity of the G-quadruplex ligand BRACO-19.

Objectives: A dynamic G-quadruplex region has been previously shown to form in the long terminal repeat (LTR) promoter of the HIV-1 integrated DNA genome. Inhibition of promoter activity and antiviral effects have been observed when this region was stabilized by BRACO-19, a trisubstituted acridine derivative that binds G-quadruplexes. Here, we aimed at characterizing the antiviral mechanism of action of BRACO-19 by analysing its activity towards a broad range of HIV-1 strains, host cells and infection modes.

Formation of a unique cluster of G-quadruplex structures in the HIV-1 Nef coding region: implications for antiviral activity.

G-quadruplexes are tetraplex structures of nucleic acids that can form in G-rich sequences. Their presence and functional role have been established in telomeres, oncogene promoters and coding regions of the human chromosome. In particular, they have been proposed to be directly involved in gene regulation at the level of transcription.

A dynamic G-quadruplex region regulates the HIV-1 long terminal repeat promoter.

G-Quadruplexes, noncanonical nucleic acid structures, act as silencers in the promoter regions of human genes; putative G-quadruplex forming sequences are also present in promoters of other mammals, yeasts, and prokaryotes. Here we show that also the HIV-1 LTR promoter exploits G-quadruplex-mediated transcriptional regulation with striking similarities to eukaryotic promoters and that treatment with a G-quadruplex ligand inhibits HIV-1 infectivity. Computational analysis on 953 HIV-1 strains substantiated a highly conserved G-rich sequence corresponding to Sp1 and NF-κB binding sites.