title: Phenyl-1-Pyridin-2yl-ethanone-based iron chelators increase IκB-α expression, modulate CDK2 and CDK9 activities, and inhibit HIV-1 transcription.
abstract: HIV-1 transcription is activated by the Tat protein, which recruits CDK9/cyclin T1 to the HIV-1 promoter. CDK9 is phosphorylated by CDK2, which facilitates formation of the high-molecular-weight positive transcription elongation factor b (P-TEFb) complex. We previously showed that chelation of intracellular iron inhibits CDK2 and CDK9 activities and suppresses HIV-1 transcription, but the mechanism of the inhibition was not understood. In the present study, we tested a set of novel iron chelators for the ability to inhibit HIV-1 transcription and elucidated their mechanism of action. Novel phenyl-1-pyridin-2yl-ethanone (PPY)-based iron chelators were synthesized and examined for their effects on cellular iron, HIV-1 inhibition, and cytotoxicity. Activities of CDK2 and CDK9, expression of CDK9-dependent and CDK2-inhibitory mRNAs, NF-κB expression, and HIV-1- and NF-κB-dependent transcription were determined. PPY-based iron chelators significantly inhibited HIV-1, with minimal cytotoxicity, in cultured and primary cells chronically or acutely infected with HIV-1 subtype B, but they had less of an effect on HIV-1 subtype C. Iron chelators upregulated the expression of IκB-α, with increased accumulation of cytoplasmic NF-κB. The iron chelators inhibited CDK2 activity and reduced the amount of CDK9/cyclin T1 in the large P-TEFb complex. Iron chelators reduced HIV-1 Gag and Env mRNA synthesis but had no effect on HIV-1 reverse transcription. In addition, iron chelators moderately inhibited basal HIV-1 transcription, equally affecting HIV-1 and Sp1- or NF-κB-driven transcription. By virtue of their involvement in targeting several key steps in HIV-1 transcription, these novel iron chelators have the potential for the development of new therapeutics for the treatment of HIV-1 infection.
authors.affiliation: Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA.
authors.forename: Namita
authors.initials: N
authors.lastname: Kumari
authors.affiliation: National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, Virginia, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Iordanskiy
authors.affiliation: ChemBio Center, National Taras Shevchenko University, Kiev, Ukraine.
authors.forename: Dmytro
authors.initials: D
authors.lastname: Kovalskyy
authors.affiliation: Viral Immunology Section, Laboratory of Molecular Virology, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, USA.
authors.forename: Denitra
authors.initials: D
authors.lastname: Breuer
authors.affiliation: Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Niu
authors.affiliation: Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA.
authors.forename: Xionghao
authors.initials: X
authors.lastname: Lin
authors.affiliation: Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.affiliation: ChemBio Center, National Taras Shevchenko University, Kiev, Ukraine.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Gavrilenko
authors.affiliation: National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, Virginia, USA.
authors.forename: Fatah
authors.initials: F
authors.lastname: Kashanchi
authors.affiliation: Viral Immunology Section, Laboratory of Molecular Virology, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, USA.
authors.forename: Subhash
authors.initials: S
authors.lastname: Dhawan
authors.affiliation: Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA snekhai@howard.edu.
authors.forename: Sergei
authors.initials: S
authors.lastname: Nekhai
mesh_terms: D002460:Cell Line; D002470:Cell Survival; D019925:Cyclin A / Q000096:biosynthesis / Q000235:genetics; D019927:Cyclin E / Q000096:biosynthesis / Q000235:genetics; D056906:Cyclin T / Q000096:biosynthesis; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D057809:HEK293 Cells; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D051550:I-kappa B Kinase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007502:Iron Chelating Agents / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D048348:Reverse Transcription / Q000187:drug effects; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects; D054299:env Gene Products, Human Immunodeficiency Virus / Q000096:biosynthesis; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000096:biosynthesis
chemical_list: C503684:CCNT1 protein, human; D019925:Cyclin A; D019927:Cyclin E; D056906:Cyclin T; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007502:Iron Chelating Agents; C498143:RELA protein, human; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D054299:env Gene Products, Human Immunodeficiency Virus; D054301:gag Gene Products, Human Immunodeficiency Virus; D051550:I-kappa B Kinase; C495894:CDK2 protein, human; C467969:CDK9 protein, human; D051357:Cyclin-Dependent Kinase 2; D042863:Cyclin-Dependent Kinase 9