The von Hippel-Lindau Cullin-RING E3 ubiquitin ligase regulates APOBEC3 cytidine deaminases.

The 7 members of the A3 family of cytidine deaminases (A3A to A3H) share a conserved catalytic activity that converts cytidines in single-stranded (ss) DNA into uridines, thereby inducing mutations. After their initial identification as cell-intrinsic defenses against HIV and other retroviruses, A3s were also found to impair many additional viruses. Moreover, some of the A3 proteins (A3A, A3B, and A3H haplotype I) are dysregulated in cancer cells, thereby causing chromosomal mutations that can be selected to fuel progression of malignancy.

Discovery of a Broad-Spectrum Antiviral Compound That Inhibits Pyrimidine Biosynthesis and Establishes a Type 1 Interferon-Independent Antiviral State.

Viral emergence and reemergence underscore the importance of developing efficacious, broad-spectrum antivirals. Here, we report the discovery of tetrahydrobenzothiazole-based compound 1, a novel, broad-spectrum antiviral lead that was optimized from a hit compound derived from a cytopathic effect (CPE)-based antiviral screen using Venezuelan equine encephalitis virus. Compound 1 showed antiviral activity against a broad range of RNA viruses, including alphaviruses, flaviviruses, influenza virus, and ebolavirus.

Genetic analysis of the localization of APOBEC3F to human immunodeficiency virus type 1 virion cores.

Unlabelled: Members of the APOBEC3 family of cytidine deaminases vary in their proportions of a virion-incorporated enzyme that is localized to mature retrovirus cores. We reported previously that APOBEC3F (A3F) was highly localized into mature human immunodeficiency virus type 1 (HIV-1) cores and identified that L306 in the C-terminal cytidine deaminase (CD) domain contributed to its core localization (C. Song, L.

Signals in APOBEC3F N-terminal and C-terminal deaminase domains each contribute to encapsidation in HIV-1 virions and are both required for HIV-1 restriction.

Human cytidine deaminases APOBEC3F (A3F) and APOBEC3G (A3G) inhibit human immunodeficiency virus type-1 (HIV-1) replication. In the absence of HIV-1 Vif, A3F and/or A3G are incorporated into assembling virions and exert antiviral functions in subsequently infected target cells. Encapsidation of A3F or A3G within the protease-matured virion core following their incorporation into virions is hypothesized to be important for the antiviral function of these proteins.

Analysis of human cell heterokaryons demonstrates that target cell restriction of cyclosporine-resistant human immunodeficiency virus type 1 mutants is genetically dominant.

The host cell protein cyclophilin A (CypA) binds to CA of human immunodeficiency virus type 1 (HIV-1) and promotes HIV-1 infection of target cells. Disruption of the CypA-CA interaction, either by mutation of the CA residue at G89 or P90 or with the immunosuppressive drug cyclosporine (CsA), reduces HIV-1 infection. Two CA mutants, A92E and G94D, previously were identified by selection for growth of wild-type HIV-1 in cultures of CD4(+) HeLa cell cultures containing CsA.

Transgenic mice for Cre-inducible overexpression of the oncogenes c-MYC and Pim-1 in multiple tissues.

The transcription factor c-MYC and the serine-threonine kinase Pim-1 have multiple roles in development and cancer, including in lymphomagenesis and prostate tumorigenesis. In some cancers, MYC and Pim-1 oncogenes are co-expressed and show marked cooperativity. To facilitate the analysis of the pathological roles of MYC and Pim-1 in specific cell types and developmental stages, we generated mice carrying Cre-inducible MYC/Pim-1 transgenes.

Chromosomal instability induced by Pim-1 is passage-dependent and associated with dysregulation of cyclin B1.

Overexpression of the oncogenic serine/threonine kinase Pim-1 has been shown to induce chromosomal missegregation and polyploidy in prostate epithelial cell lines (1). Here we demonstrated that Pim-1-induced polyploidy develops in a passage-dependent manner in culture consistent with a stochastic mode of progression. Induction of chromosomal instability by Pim-1 was not restricted to prostate cells as it was also observed in telomerase-immortalized normal human mammary epithelial cells.

Activity of the Mason-Pfizer monkey virus fusion protein is modulated by single amino acids in the cytoplasmic tail.

Mason-Pfizer monkey virus (M-PMV) encodes a transmembrane glycoprotein with a 38-amino-acid-long cytoplasmic tail. After the release of the immature virus, a viral protease-mediated cleavage of the cytoplasmic tail (CT) results in the loss of 17 amino acids from the carboxy terminus and renders the envelope protein fusion competent. To investigate the role of individual amino acid residues in the CT in fusion, a series of mutations was introduced, and the effects of these mutations on glycoprotein biosynthesis and fusion were examined.

Amino acid residues in the cytoplasmic domain of the Mason-Pfizer monkey virus glycoprotein critical for its incorporation into virions.

Assembly of an infectious retrovirus requires the incorporation of the envelope glycoprotein complex during the process of particle budding. We have recently demonstrated that amino acid substitutions of a tyrosine residue in the cytoplasmic domain block glycoprotein incorporation into budding Mason-Pfizer monkey virus (M-PMV) particles and abrogate infectivity (C. Song, S.

Overexpression of the oncogenic kinase Pim-1 leads to genomic instability.

Aneuploidy and chromosomal aberrations are hallmarks of most human epithelial malignancies. Here we show that overexpression of the oncogenic kinase Pim-1 in human prostate epithelial cells induces genomic instability by subverting the mitotic spindle checkpoint. Cells overexpressing Pim-1 have a defect in the mitotic spindle checkpoint, abnormal mitotic spindles, centrosome amplification, and chromosome missegregation.

Variable sensitivity to substitutions in the N-terminal heptad repeat of Mason-Pfizer monkey virus transmembrane protein.

The transmembrane protein of Mason-Pfizer monkey virus contains two heptad repeats that are predicted to form amphipathic alpha-helices that mediate the conformational change necessary for membrane fusion. To analyze the relative sensitivity of the predicted hydrophobic face of the N-terminal heptad repeat to the insertion of uncharged, polar, and charged substitutions, mutations that introduced alanine, serine, or glutamic acid into positions 436, 443, 450, and 457 of the envelope protein were examined. Novel systems using Tat protein and the GHOST cell line were developed to test and quantitate the effects of the mutations on Env-mediated fusion and infectivity of the virus.

A tyrosine motif in the cytoplasmic domain of mason-pfizer monkey virus is essential for the incorporation of glycoprotein into virions.

Mason-Pfizer monkey virus (M-PMV) encodes a transmembrane (TM) glycoprotein with a 38-amino-acid-long cytoplasmic domain. After the release of the immature virus, a viral protease-mediated cleavage occurs within the cytoplasmic domain, resulting in the loss of 17 amino acids from the carboxy terminus. This maturational cleavage occurs between a histidine at position 21 and a tyrosine at position 22 in the cytoplasmic domain of the TM protein.