scholarly journals Apo2L/TRAIL induction and nuclear translocation of inositol hexakisphosphate kinase 2 during IFN-β-induced apoptosis in ovarian carcinoma

2005 ◽  
Vol 385 (2) ◽  
pp. 595-603 ◽  
Author(s):  
Bei H. MORRISON ◽  
Zhuo TANG ◽  
Barbara S. JACOBS ◽  
Joseph A. BAUER ◽  
Daniel J. LINDNER
Keyword(s):  
Fusion Protein ◽  
Ovarian Carcinoma ◽  
Vector Control ◽  
Nuclear Localization ◽  
Nuclear Localization Sequence ◽  
Inositol Hexakisphosphate ◽  
Potent Inducer ◽  
Ic50 Value ◽  
Induced Apoptosis ◽  
Apoptotic Effects

Previously, we have reported that overexpression of IHPK2 (inositol hexakisphosphate kinase 2) sensitized NIH-OVCAR-3 ovarian carcinoma cell lines to the growth-suppressive and apoptotic effects of IFN-β (interferon-β) treatment and γ-irradiation. In the present study, we demonstrate that Apo2L/TRAIL (Apo2L/tumour-necrosis-factor-related apoptosis-inducing ligand) is a critical mediator of IFN-induced apoptosis in these cells. Compared with IFN-α2, IFN-β is a more potent inducer of Apo2L/TRAIL and IHPK2 activity. Overexpression of IHPK2 converts IFN-α2-resistant cells into cells that readily undergo apoptosis in response to IFN-α2. In untreated cells transfected with IHPK2-eGFP (where eGFP stands for enhanced green fluorescent protein), the fusion protein is localized to the cytoplasm and perinuclear region. After treatment with IFN-β, IHPK2-eGFP translocated to the nucleus. In cells transfected with mutant IHPK2-NLS-eGFP (where NLS stands for nuclear localization sequence), containing point mutations in the NLS, the fusion protein remained trapped in the cytoplasm, even after IFN-β treatment. Cells expressing mutant NLS mutation were more resistant to IFN-β. The IC50 value of IHPK2-expressing cells was 2–3-fold lower than vector control. The IC50 value of NLS-mutant-expressing cells was 3-fold higher than vector control. Blocking antibodies to Apo2L/TRAIL or transfection with a dominant negative Apo2L/TRAIL receptor (DR5Δ) inhibited the antiproliferative effects of IFN-β. Thus overexpression of IHPK2 enhanced apoptotic effects of IFN-β, and expression of the NLS mutant conferred resistance to IFN-β. Apo2L/TRAIL expression and nuclear localization of IHPK2 are both required for the induction of apoptosis by IFN-β in ovarian carcinoma.

scholarly journals Degradation of SAMHD1 by Vpx Is Independent of Uncoating

2015 ◽  
Vol 89 (10) ◽  
pp. 5701-5713 ◽  
Author(s):  
Paula Jáuregui ◽  
Eric C. Logue ◽  
Megan L. Schultz ◽  
Stephanie Fung ◽  
Nathaniel R. Landau
Keyword(s):  
T Cells ◽  
Green Fluorescent Protein ◽  
Fusion Protein ◽  
Hela Cell ◽  
Nuclear Localization ◽  
Fluorescent Protein ◽  
Nuclear Localization Sequence ◽  
Hela Cell Lines ◽  
Localization Sequence ◽  
Green Fluorescent

ABSTRACTSterile alpha motif domain and HD domain-containing protein 1 (SAMHD1) restricts human immunodeficiency virus type 1 (HIV-1) replication in myeloid and resting T cells. Lentiviruses such as HIV-2 and some simian immunodeficiency viruses (SIVs) counteract the restriction by encoding Vpx or Vpr, accessory proteins that are packaged in virions and which, upon entry of the virus into the cytoplasm, induce the proteasomal degradation of SAMHD1. As a tool to study these mechanisms, we generated HeLa cell lines that express a fusion protein termed NLS.GFP.SAM595 in which the Vpx binding domain of SAMHD1 is fused to the carboxy terminus of green fluorescent protein (GFP) and a nuclear localization signal is fused to the amino terminus of GFP. Upon incubation of Vpx-containing virions with the cells, the NLS.GFP.SAM595 fusion protein was degraded over several hours and the levels remained low over 5 days as the result of continued targeting of the CRL4 E3 ubiquitin ligase. Degradation of the fusion protein required that it contain a nuclear localization sequence. Fusion to the cytoplasmic protein muNS rendered the protein resistant to Vpx-mediated degradation, confirming that SAMHD1 is targeted in the nucleus. Virions treated with protease inhibitors failed to release Vpx, indicating that Gag processing was required for Vpx release from the virion. Mutations in the capsid protein that altered the kinetics of virus uncoating and the Gag binding drug PF74 had no effect on the Vpx-mediated degradation. These results suggest that Vpx is released from virions without a need for uncoating of the capsid, allowing Vpx to transit to the nucleus rapidly upon entry into the cytoplasm.IMPORTANCESAMHD1 restricts lentiviral replication in myeloid cells and resting T cells. Its importance is highlighted by the fact that viruses such as HIV-2 encode an accessory protein that is packaged in the virion and is dedicated to inducing SAMHD1 degradation. Vpx needs to act rapidly upon infection to allow reverse transcription to proceed. The limited number of Vpx molecules in a virion also needs to clear the cell of SAMHD1 over a prolonged period of time. Using an engineered HeLa cell line that expresses a green fluorescent protein (GFP)-SAMHD1 fusion protein, we showed that the Vpx-dependent degradation occurs without a need for viral capsid uncoating. In addition, the fusion protein was degraded only when it was localized to the nucleus, confirming that SAMHD1 is targeted in the nucleus and thus explaining why Vpx also localizes to the nucleus.

Amino acid sequences that determine the nuclear localization of yeast histone 2B

1987 ◽  
Vol 7 (11) ◽  
pp. 4048-4057
Author(s):  
R B Moreland ◽  
G L Langevin ◽  
R H Singer ◽  
R L Garcea ◽  
L M Hereford
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fusion Protein ◽  
Point Mutation ◽  
Nuclear Localization ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Amino Acid Sequences ◽  
Nuclear Localization Sequence ◽  
Beta Galactosidase

Histone-beta-galactosidase protein fusions were used to identify the domain of yeast histone 2B, which targets this protein to the nucleus. Amino acids 28 to 33 in H2B were required for nuclear localization of such fusion proteins and thus constitute a nuclear localization sequence. The amino acid sequence in this region (Gly-29 Lys Lys Arg Ser Lys Ala) is similar to the nuclear location signal in simian virus 40 large T antigen (Pro-126 Lys Lys Lys Arg Lys Val) (D. Kalderon, B.L. Roberts, W.D. Richardson, and A.E. Smith, Cell 39:499-509, 1984). A point mutation changing lysine 31 to methionine abolished nuclear localization of an H2B-beta-galactosidase fusion protein containing amino acids 1 to 33 of H2B. However, an H2B-beta-galactosidase fusion protein containing both this point mutation and the H2A interaction domain of H2B was nuclear localized. These results suggest that H2A and H2B may be cotransported to the nucleus as a heterodimer.

scholarly journals Multiple regions of NSR1 are sufficient for accumulation of a fusion protein within the nucleolus.

1993 ◽  
Vol 123 (5) ◽  
pp. 1081-1091 ◽  
Author(s):  
C Yan ◽  
T Mélèse
Keyword(s):  
Fusion Protein ◽  
Nuclear Localization ◽  
Ribosome Biogenesis ◽  
Nuclear Localization Sequence ◽  
Rna Recognition Motif ◽  
Rna Recognition ◽  
Rich Region ◽  
Rna Recognition Motifs ◽  
Recognition Motifs ◽  
Beta Galactosidase

NSR1, a 67-kD nucleolar protein, was originally identified in our laboratory as a nuclear localization signal binding protein, and has subsequently been found to be involved in ribosome biogenesis. NSR1 has three regions: an acidic/serine-rich NH2 terminus, two RNA recognition motifs, and a glycine/arginine-rich COOH terminus. In this study we show that NSR1 itself has a bipartite nuclear localization sequence. Deletion of either basic amino acid stretch results in the mislocation of NSR1 to the cytoplasm. We further demonstrate that either of two regions, the NH2 terminus or both RNA recognition motifs, are sufficient to localize a bacterial protein, beta-galactosidase, to the nucleolus. Intensive deletion analysis has further defined a specific acidic/serine-rich region within the NH2 terminus as necessary for nucleolar accumulation rather than nucleolar targeting. In addition, deletion of either RNA recognition motif or point mutations in one of the RNP consensus octamers results in the mislocalization of a fusion protein within the nucleus. Although the glycine/arginine-rich region in the COOH terminus is not sufficient to bring beta-galactosidase to the nucleolus, our studies show that this domain is necessary for nucleolar accumulation when an RNP consensus octamer in one of the RNA recognition motifs is mutated. Our findings are consistent with the notion that nucleolar localization is a result of the binding interactions of various domains of NSR1 within the nucleolus rather than the presence of a specific nucleolar targeting signal.

scholarly journals Amino acid sequences that determine the nuclear localization of yeast histone 2B.

1987 ◽  
Vol 7 (11) ◽  
pp. 4048-4057 ◽  
Author(s):  
R B Moreland ◽  
G L Langevin ◽  
R H Singer ◽  
R L Garcea ◽  
L M Hereford
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fusion Protein ◽  
Point Mutation ◽  
Nuclear Localization ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Amino Acid Sequences ◽  
Nuclear Localization Sequence ◽  
Beta Galactosidase

Histone-beta-galactosidase protein fusions were used to identify the domain of yeast histone 2B, which targets this protein to the nucleus. Amino acids 28 to 33 in H2B were required for nuclear localization of such fusion proteins and thus constitute a nuclear localization sequence. The amino acid sequence in this region (Gly-29 Lys Lys Arg Ser Lys Ala) is similar to the nuclear location signal in simian virus 40 large T antigen (Pro-126 Lys Lys Lys Arg Lys Val) (D. Kalderon, B.L. Roberts, W.D. Richardson, and A.E. Smith, Cell 39:499-509, 1984). A point mutation changing lysine 31 to methionine abolished nuclear localization of an H2B-beta-galactosidase fusion protein containing amino acids 1 to 33 of H2B. However, an H2B-beta-galactosidase fusion protein containing both this point mutation and the H2A interaction domain of H2B was nuclear localized. These results suggest that H2A and H2B may be cotransported to the nucleus as a heterodimer.

Apoptotic Effects of N-(2-hydroxyphenyl)-2-propylpentanamide on U87-MG and U-2 OS Cells and Antiangiogenic Properties

2020 ◽  
Vol 20 ◽  
Author(s):  
Paola Castillo-Juárez ◽  
Sebastián C. Sanchez ◽  
Alma D. Chávez-Blanco ◽  
Humberto Mendoza-Figueroa ◽  
José Correa-Basurto
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Histone Deacetylases ◽  
Biochemical Mechanism ◽  
Antiproliferative Effects ◽  
Human Osteosarcoma ◽  
Antiproliferative Agent ◽  
Induced Apoptosis ◽  
Apoptotic Effects

Background and Objective: Histone deacetylases (HDACs) are important therapeutic targets for many types of human cancers. A derivative of valproic acid, N-(2-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA), has antiproliferative properties on some cancer cell lines and inhibits the HDAC1 isoform. Materials and Methods: In this work, HO-AAVPA was tested as an antiproliferative agent in U87-MG (human glioblastoma) and U-2 OS cells (human osteosarcoma), which are types of cancer that are difficult to treat, and its antiangiogenic properties were explored. Results: HO-AAVPA had antiproliferative effects at 48 h with an IC50 = 0.655 mM in U87-MG cells and an IC50 = 0.453 mM in U-2 OS cells. Additionally, in the colony formation assay, HO-AAVPA decreased the number of colonies by approximately 99% in both cell lines and induced apoptosis by 31.3% in the U-2 OS cell line and by 78.2% in the U87-MG cell line. Additionally, HO-AAVPA reduced the number of vessels in chorioallantoid membranes (CAMs) by approximately 67.74% and IL-6 levels in both cell lines suggesting that the biochemical mechanism on cancer cell of HO-AAVPA is different compared to VPA. Conclusion: HO-AAVPA has antiproliferative effects on glioblastoma and osteosarcoma and antiangiogenic properties.

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