scholarly journals A Fragment-Based Approach for the Development of G-Quadruplex Ligands: Role of the Amidoxime Moiety

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1874 ◽  
Author(s):  
Martina Tassinari ◽  
Alberto Lena ◽  
Elena Butovskaya ◽  
Valentina Pirota ◽  
Matteo Nadai ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Screening Methods ◽  
Lead Compounds ◽  
Immunodeficiency Virus ◽  
G Quadruplex ◽  
Preferential Binding ◽  
Nucleic Acid Structures ◽  
Hiv 1

G-quadruplex (G4) nucleic acid structures have been reported to be involved in several human pathologies, including cancer, neurodegenerative disorders and infectious diseases; however, G4 targeting compounds still need implementation in terms of drug-like properties and selectivity in order to reach the clinical use. So far, G4 ligands have been mainly identified through high-throughput screening methods or design of molecules with pre-set features. Here, we describe the development of new heterocyclic ligands through a fragment-based drug discovery (FBDD) approach. The ligands were designed against the major G4 present in the long terminal repeat (LTR) promoter region of the human immunodeficiency virus-1 (HIV-1), the stabilization of which has been shown to suppress viral gene expression and replication. Our method is based on the generation of molecular fragment small libraries, screened against the target to further elaborate them into lead compounds. We screened 150 small molecules, composed by structurally and chemically different fragments, selected from commercially available and in-house compounds; synthetic elaboration yielded several G4 ligands and two final G4 binders, both embedding an amidoxime moiety; one of these two compounds showed preferential binding for the HIV-1 LTR G4. This work presents the discovery of a novel potential pharmacophore and highlights the possibility to apply a fragment-based approach to develop G4 ligands with unexpected chemical features.

scholarly journals Recruitment of Tat to Heterochromatin Protein HP1 via Interaction with CTIP2 Inhibits Human Immunodeficiency Virus Type 1 Replication in Microglial Cells

2003 ◽  
Vol 77 (9) ◽  
pp. 5415-5427 ◽  
Author(s):  
Olivier Rohr ◽  
Dominique Lecestre ◽  
Sylvette Chasserot-Golaz ◽  
Céline Marban ◽  
Dorina Avram ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Gene Expression ◽  
Microglial Cells ◽  
Viral Gene ◽  
Binding Interface ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The Tat protein of human immunodeficiency virus type 1 (HIV-1) plays a key role as inducer of viral gene expression. We report that Tat function can be potently inhibited in human microglial cells by the recently described nuclear receptor cofactor chicken ovalbumin upstream promoter transcription factor-interacting protein 2 (CTIP2). Overexpression of CTIP2 leads to repression of HIV-1 replication, as a result of inhibition of Tat-mediated transactivation. In contrast, the related CTIP1 was unable to affect Tat function and viral replication. Using confocal microscopy to visualize Tat subcellular distribution in the presence of the CTIPs, we found that overexpression of CTIP2, and not of CTIP1, leads to disruption of Tat nuclear localization and recruitment of Tat within CTIP2-induced nuclear ball-like structures. In addition, our studies demonstrate that CTIP2 colocalizes and associates with the heterochromatin-associated protein HP1α. The CTIP2 protein harbors two Tat and HP1 interaction interfaces, the 145-434 and the 717-813 domains. CTIP2 and HP1α associate with Tat to form a three-protein complex in which the 145-434 CTIP2 domain interacts with the N-terminal region of Tat, while the 717-813 domain binds to HP1. The importance of this Tat binding interface and of Tat subnuclear relocation was confirmed by analysis of CTIP2 deletion mutants. Our findings suggest that inhibition of HIV-1 expression by CTIP2 correlates with recruitment of Tat within CTIP2-induced structures and relocalization within inactive regions of the chromatin via formation of the Tat-CTIP2-HP1α complex. These data highlight a new mechanism of Tat inactivation through subnuclear relocalization that may ultimately lead to inhibition of viral pathogenesis.

scholarly journals Contribution of Vpu, Env, and Nef to CD4 Down-Modulation and Resistance of Human Immunodeficiency Virus Type 1-Infected T Cells to Superinfection

2006 ◽  
Vol 80 (16) ◽  
pp. 8047-8059 ◽  
Author(s):  
Steffen Wildum ◽  
Michael Schindler ◽  
Jan Münch ◽  
Frank Kirchhoff
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Virus Production ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) utilizes Vpu, Env, and Nef to down-modulate its primary CD4 receptor from the cell surface, and this function seems to be critical for the pathogenesis of AIDS. The physiological relevance of CD4 down-modulation, however, is currently not well understood. In the present study, we analyzed the kinetics of CD4 down-modulation and the susceptibility of HIV-1-infected T cells to superinfection using proviral HIV-1 constructs containing individual and combined defects in vpu, env, and nef and expressing red or green fluorescent proteins. T cells infected with HIV-1 mutants containing functional nef genes expressed low surface levels of CD4 from the first moment that viral gene expression became detectable. In comparison, Vpu and Env had only minor to moderate effects on CD4 during later stages of infection. Consistent with these quantitative differences, Nef inhibited superinfection more efficiently than Vpu and Env. Notably, nef alleles from AIDS patients were more effective in preventing superinfection than those derived from a nonprogressor of HIV-1 infection. Our data suggest that protection against X4-tropic HIV-1 superinfection involves both CD4-independent and CD4-dependent mechanisms of HIV-1 Nef. X4 was effectively down-regulated by simian immunodeficiency virus and HIV-2 but not by HIV-1 Nef proteins. Thus, maximal protection seems to involve an as-yet-unknown mechanism that is independent of CD4 or coreceptor down-modulation. Finally, we demonstrate that superinfected primary T cells show enhanced levels of apoptosis. Accordingly, one reason that HIV-1 inhibits CD4 surface expression and superinfection is to prevent premature cell death in order to expand the period of effective virus production.

Helical polymers of the REV protein of human immunodeficiency virus 1

1992 ◽  
Vol 50 (1) ◽  
pp. 456-457
Author(s):  
Manoj Misra ◽  
Benes L. Trus ◽  
Paul Wingfield ◽  
Alasdair C. Steven
Keyword(s):  
Rna Virus ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Helical Polymers ◽  
Immunodeficiency Virus ◽  
Viral Gene Product ◽  
Active Proliferation ◽  
Hiv 1 ◽  
Rev Protein

The pattern of viral gene expression in cells infected with HIV-1 is orchestrated by several regulatory proteins. One such viral gene product is Rev (regulator of expression of virus), a 13 kDa basic protein that plays a crucial role in determining whether full-length transcripts coding for the major structural proteins of HIV-1 are exported intact from the nucleus into the cytoplasm, so that active proliferation of the virus can ensue. Purified Rov has been shown to polymerize in vitro into long filamentous polymers. Based on this and other observations, it has been hypothesized that Rev functions rather like the nucleocapsid protein of a filamentous RNA virus, and that coating of the transcripts in question by Rev is the mechanism whereby they are protected from splicing. To explore this hypothesis further, we have studied the structure of these Rev polymers in greater detail.

scholarly journals Fourth NF-κB site in HIV-1 subtype-C LTR confers functional advantage to viral gene expression

Retrovirology ◽  
2009 ◽  
Vol 6 (S2) ◽  
Author(s):  
Mahesh Bachu ◽  
Rajesh V Murali ◽  
Anil MHKH Babu ◽  
Venkat SRK Yedavalli ◽  
Kuan-Teh Jeang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Subtype C ◽  
Functional Advantage ◽  
Hiv 1

scholarly journals Functional Differences between Human and Bovine Immunodeficiency Virus Tat Transcription Factors

2000 ◽  
Vol 74 (10) ◽  
pp. 4666-4671 ◽  
Author(s):  
Hal P. Bogerd ◽  
Heather L. Wiegand ◽  
Paul D. Bieniasz ◽  
Bryan R. Cullen
Keyword(s):  
Cooperative Interaction ◽  
Bovine Immunodeficiency Virus ◽  
Viral Gene ◽  
Tat Protein ◽  
Cyclin T1 ◽  
Immunodeficiency Virus ◽  
Cellular Cofactor ◽  
Ltr Promoter ◽  
Hiv 1

ABSTRACT Transcriptional transactivation of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) promoter element by the essential viral Tat protein requires recruitment of positive transcription elongation factor b (P-TEFb) to the viral TAR RNA target. The recruitment of P-TEFb, which has been proposed to be necessary and sufficient for activation of viral gene expression, is mediated by the highly cooperative interaction of Tat and cyclin T1, an essential component of P-TEFb, with the HIV-1 TAR element. Species, such as rodents, that encode cyclin T1 variants that are unable to support TAR binding by the Tat-cyclin T1 heterodimer are also unable to support HIV-1 Tat function. In contrast, we here demonstrate that the bovine immunodeficiency virus (BIV) Tat protein is fully able to bind to BIV TAR both in vivo and in vitro in the absence of any cellular cofactor. Nevertheless, BIV Tat can specifically recruit cyclin T1 to the BIV TAR element, and this recruitment is as essential for BIV Tat function as it is for HIV-1 Tat activity. However, because the cyclin T1 protein does not contribute to TAR binding, BIV Tat is able to function effectively in cells from several species that do not support HIV-1 Tat function. Thus, BIV Tat, while apparently dependent on the same cellular cofactor as the Tat proteins encoded by other lentiviruses, is nevertheless unique in terms of the mechanism used to recruit the BIV Tat-cyclin T1 complex to the viral LTR promoter.

scholarly journals Impact of Tat Genetic Variation on HIV-1 Disease

2012 ◽  
Vol 2012 ◽  
pp. 1-28 ◽  
Author(s):  
Luna Li ◽  
Satinder Dahiya ◽  
Sandhya Kortagere ◽  
Benjamas Aiamkitsumrit ◽  
David Cunningham ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Transcriptional Activation ◽  
Viral Gene Expression ◽  
Functional Domains ◽  
Viral Gene ◽  
Molecular Architecture ◽  
Viral Transactivator ◽  
Hiv Drugs ◽  
Hiv 1

The human immunodeficiency virus type 1 (HIV-1) promoter or long-terminal repeat (LTR) regulates viral gene expression by interacting with multiple viral and host factors. The viral transactivator protein Tat plays an important role in transcriptional activation of HIV-1 gene expression. Functional domains of Tat and its interaction with transactivation response element RNA and cellular transcription factors have been examined. Genetic variation withintatof different HIV-1 subtypes has been shown to affect the interaction of the viral transactivator with cellular and/or viral proteins, influencing the overall level of transcriptional activation as well as its action as a neurotoxic protein. Consequently, the genetic variability withintatmay impact the molecular architecture of functional domains of the Tat protein that may impact HIV pathogenesis and disease. Tat as a therapeutic target for anti-HIV drugs has also been discussed.

scholarly journals Oxadiazole/Pyridine-Based Ligands: A Structural Tuning for Enhancing G-Quadruplex Binding

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2162 ◽  
Author(s):  
Filippo Doria ◽  
Valentina Pirota ◽  
Michele Petenzi ◽  
Marie-Paule Teulade-Fichou ◽  
Daniela Verga ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Structural Transition ◽  
Binding Mode ◽  
Telomeric Sequence ◽  
Recognition Element ◽  
New Family ◽  
G Quadruplex ◽  
Preferential Binding ◽  
High Cytotoxicity ◽  
Nucleic Acid Structures

Non-macrocyclic heteroaryls represent a valuable class of ligands for nucleic acid recognition. In this regard, non-macrocyclic pyridyl polyoxazoles and polyoxadiazoles were recently identified as selective G-quadruplex stabilizing compounds with high cytotoxicity and promising anticancer activity. Herein, we describe the synthesis of a new family of heteroaryls containing oxadiazole and pyridine moieties targeting DNA G-quadruplexes. To perform a structure–activity analysis identifying determinants of activity and selectivity, we followed a convergent synthetic pathway to modulate the nature and number of the heterocycles (1,3-oxazole vs. 1,2,4-oxadiazole and pyridine vs. benzene). Each ligand was evaluated towards secondary nucleic acid structures, which have been chosen as a prototype to mimic cancer-associated G-quadruplex structures (e.g., the human telomeric sequence, c-myc and c-kit promoters). Interestingly, heptapyridyl-oxadiazole compounds showed preferential binding towards the telomeric sequence (22AG) in competitive conditions vs. duplex DNA. In addition, G4-FID assays suggest a different binding mode from the classical stacking on the external G-quartet. Additionally, CD titrations in the presence of the two most promising compounds for affinity, TOxAzaPy and TOxAzaPhen, display a structural transition of 22AG in K-rich buffer. This investigation suggests that the pyridyl-oxadiazole motif is a promising recognition element for G-quadruplexes, combining seven heteroaryls in a single binding unit.

scholarly journals 8 Implication of the HIV-1 pol gene intragenic enhancer in myeloid-specific viral gene expression

2017 ◽  
Vol 3 ◽  
pp. 8
Author(s):  
R. Verdikt ◽  
L. Colin ◽  
C. Vanhulle ◽  
B. Van Driessche ◽  
A. Kula ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Hiv 1

scholarly journals Evidence for Gene Expression by Unintegrated Human Immunodeficiency Virus Type 1 DNA Species

2004 ◽  
Vol 78 (20) ◽  
pp. 11263-11271 ◽  
Author(s):  
Audrey Brussel ◽  
Pierre Sonigo
Keyword(s):  
Gene Expression ◽  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Gene ◽  
Viral Expression ◽  
Molecular Stability ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The integrated form of human immunodeficiency virus type 1 (HIV-1) DNA is classically considered to be the sole template for viral gene expression. However, several studies have suggested that unintegrated viral DNA species could also support transcription. To determine the contribution of the different species of HIV-1 DNA to viral expression, we first monitored intracellular levels of various HIV-1 DNA and RNA species in a single-round infection assay. We observed that, in comparison to the precocity of HIV-1 DNA synthesis, viral expression was delayed, suggesting that only the HIV-1 DNA species that persist for a sufficient period of time would be transcribed efficiently. We next evaluated the transcriptional activity of the circular forms of HIV-1 DNA bearing two long terminal repeats, since these episomes were reported to exhibit an intrinsic molecular stability. Our results support the notion that these circular species of HIV-1 DNA are naturally transcribed during HIV-1 infection, thereby participating in virus replication.

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