Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The availability of a patient with basophilic leukemia manifesting 75 to 90% mature basophils permitted the use of a cell concentration sufficient to generate and release mediators upon interaction with a calcium ionophore in quantities adequate for their physiocochemical characterization. The mediators were defined in terms of their physicochemical characteristics: slow reacting substance of anaphylaxis (SRS-A) by purification through silicic acid chromatography and inactivation by arylsulfatase; eosinophil chemotactic factor of anaphylaxis (ECF-A) by its gel filtration through Sephadex G-25 and inactivation by subtilisin and not trypsin; and platelet-activating factor (PAF) by its inherent binding to albumin. Both ECF-A and histamine were present in their preformed state, and for histamine it was possible to establish that the concentration per cell was comparable to that of normal human basophils. Dibutyryl cyclic AMP suppressed release of histamine and SRS-A, indicating that their availability was under a control similar to that observed with normal cells subjected to immunologic activation. The demonstration that a suspension of leukemic human basophils contained the preformed mediators, histamine and ECF-A, and generated SRS-A and PAF for release along with histamine and ECF-A, after activation with a calcium ionophore, establishes that a single cell type can serve as a source of the four recognized mediators of immediate-type hypersensitivity.
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PMID:The release of four mediators of immediate hypersensitivity from human leukemic basophils. 4 47

The primary objective of this study was to examine the feasibility of using a mouse model to evaluate the immunogenicity of proteins as a potential method to determine occupational exposure guidelines. Mice were intratracheally administered a benchmark protein allergen, subtilisin Carlsberg (Alcalase) in detergent matrix once a week for 4 to 6 weeks and specific IgE and IgG1 levels were determined. In all experiments, specific IgE levels were determined by using a rat basophilic leukemia cell (RBL) release assay, while specific IgG1 was measured by an ELISA. A good correlation was observed between IgE titers determined by the RBL assay and rat passive cutaneous anaphylaxis assay. Intratracheal administration of protease with detergent matrix was found to result in significant IgE and IgG1 responses that were dose related. Detergent matrix was found to enhance the Alcalase-specific IgE and IgG1 response when administered by the intratracheal route. The IgG1 response was much more robust, easier to measure, and found to follow the IgE response. These results suggest that a mouse intratracheal model is a feasible approach to examining the immunogenic potency of enzymes using specific IgE or IgG1 as the end points. Additional development and validation of the mouse model with other types of proteins will be pursued.
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PMID:Specific IgE and IgG1 responses to subtilisin Carlsberg (Alcalase) in mice: development of an intratracheal exposure model. 874 21

Human immunodeficiency virus type 1 (HIV-1) gag-encoded proteins play key functions at almost all stages of the viral life cycle. Since these functions may require association with cellular factors, the HIV-1 matrix protein (MA) was used as bait in a yeast two-hybrid screen to identify MA-interacting proteins. MA was found to interact with elongation factor 1-alpha (EF1alpha), an essential component of the translation machinery that delivers aminoacyl-tRNA to ribosomes. EF1alpha was then shown to bind the entire HIV-1 Gag polyprotein. This interaction is mediated not only by MA, but also by the nucleocapsid domain, which provides a second, independent EF1alpha-binding site on the Gag polyprotein. EF1alpha is incorporated within HIV-1 virion membranes, where it is cleaved by the viral protease and protected from digestion by exogenously added subtilisin. The specificity of the interaction is demonstrated by the fact that EF1alpha does not bind to nonlentiviral MAs and does not associate with Moloney murine leukemia virus virions. The Gag-EF1alpha interaction appears to be mediated by RNA, in that basic residues in MA and NC are required for binding to EF1alpha, RNase disrupts the interaction, and a Gag mutant with undetectable EF1alpha-binding activity is impaired in its ability to associate with tRNA in cells. Finally, the interaction between MA and EF1alpha impairs translation in vitro, a result consistent with a previously proposed model in which inhibition of translation by the accumulation of Gag serves to release viral RNA from polysomes, permitting the RNA to be packaged into nascent virions.
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PMID:Translation elongation factor 1-alpha interacts specifically with the human immunodeficiency virus type 1 Gag polyprotein. 1036 86

Human Staufen (hStau), a double-stranded RNA (dsRNA)-binding protein that is involved in mRNA transport, is incorporated in human immunodeficiency virus type 1 (HIV-1) and in other retroviruses, including HIV-2 and Moloney murine leukemia virus. Sucrose and Optiprep gradient analyses reveal cosedimentation of hStau with purified HIV-1, while subtilisin assays demonstrate that it is internalized. hStau incorporation in HIV-1 is selective, is dependent on an intact functional dsRNA-binding domain, and quantitatively correlates with levels of encapsidated HIV-1 genomic RNA. By coimmunoprecipitation and reverse transcription-PCR analyses, we demonstrate that hStau is associated with HIV-1 genomic RNA in HIV-1-expressing cells and purified virus. Overexpression of hStau enhances virion incorporation levels, and a corresponding, threefold increase in HIV-1 genomic RNA encapsidation levels. This coordinated increase in hStau and genomic RNA packaging had a significant negative effect on viral infectivity. This study is the first to describe hStau within HIV-1 particles and provides evidence that hStau binds HIV-1 genomic RNA, indicating that it may be implicated in retroviral genome selection and packaging into assembling virions.
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PMID:The double-stranded RNA-binding protein Staufen is incorporated in human immunodeficiency virus type 1: evidence for a role in genomic RNA encapsidation. 1082 48

Interferons display a wide range of antiviral, antiproliferative, and immunomodulatory activities on a variety of cell types and have been used to treat many diseases including hairy-cell leukemia and hepatitis B and C and have also been applied to other therapeutic areas. To improve the pharmacological properties of interferon (IFN) alpha-2b, a long-acting pegylated form (PEG-IFN) has been developed [PEG, monomethoxy poly(ethylene glycol) with average molecular mass of 12 000 Da]. PEG-IFN is a mixture of pegylated proteins with differing sites of PEG attachment. To identify the major positional isomer in the pegylated material [PEG-IFN(His-34)], NMR studies were conducted on a subtilisin-digested N-acetylated peptide of the major positional isomer [PEG-IFN(His-34)dig], synthetic peptide analogues containing His-34, as well as unmodified IFN and PEG-IFN(His-34). Our studies reveal a novel interferon-polymer attachment site as a histidine-linked interferon conjugate. We show that the major component of PEG-IFN is pegylated in the imidazole side chain of histidine-34. Chemical shift data suggest that pegylation occurs mainly at the N(delta)(1) position in the imidazole side chain of this residue. This positional isomer, PEG-IFN(His-34), comprises approximately 47% of the total pegylated species when PEG-IFN is synthesized under the current experimental conditions at pH 6.5 with an electrophilic derivative of PEG, succinimidyl carbonate PEG. The reversibility of the histidine modification was examined. The PEG-imidazole adduct in the intact protein, PEG-IFN(His-34), is labile but much more stable than in the peptide, PEG-IFN(His-34)dig. Apparently, the tertiary structure of the intact protein protects the His(34)-imidazole ring from depegylation.
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PMID:Identification of the major positional isomer of pegylated interferon alpha-2b. 1097 46

Barrier-to-autointegration factor (BAF) is a conserved human chromatin protein exploited by retroviruses. Previous investigators showed that BAF binds double-stranded DNA nonspecifically and is a host component of preintegration complexes (PICs) isolated from cells infected with human immunodeficiency virus type 1 (HIV-1) or Moloney murine leukemia virus. BAF protects PIC structure and stimulates the integration of salt-stripped PICs into target DNA in vitro. PICs are thought to acquire BAF from the cytoplasm during infection. However, we identified two human tissues (of 16 tested) in which BAF mRNA was not detected: thymus and peripheral blood leukocytes, which are enriched in CD4(+) T lymphocytes and macrophage precursors, respectively. BAF protein was detected in activated but not resting CD4(+) T lymphocytes; thus, if BAF were essential for PIC function, we hypothesized that virions might "bring their own BAF." Supporting this model, BAF copurified with HIV-1 virions that were digested with subtilisin to remove microvesicle contaminants, and BAF was present in approximately zero to three copies per virion. In three independent assays, BAF bound directly to both p55 Gag (the structural precursor of HIV-1 virions) and its cleaved product, matrix. Using lysates from cells overexpressing Gag, endogenous BAF and Gag were coimmunoprecipitated by antibodies against Gag. Purified recombinant BAF had low micromolar affinities (1.1 to 1.4 micro M) for recombinant Gag and matrix. We conclude that BAF is present at low levels in incoming virions, in addition to being acquired from the cytoplasm of newly infected cells. We further conclude that BAF might contribute to the assembly or activity of HIV-1 PICs through direct binding to matrix, as well as DNA.
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PMID:Barrier-to-autointegration factor BAF binds p55 Gag and matrix and is a host component of human immunodeficiency virus type 1 virions. 1464 65

Retroviral envelope glycoproteins undergo proteolytic processing by cellular subtilisin-like proprotein convertases at a polybasic amino-acid site in order to produce the two functional subunits, SU and TM. Most previous studies have indicated that envelope-protein cleavage is required for rendering the protein competent for promoting membrane fusion and for virus infectivity. We have investigated the role of proteolytic processing of the Moloney murine leukemia virus envelope-protein through site-directed mutagenesis of the residues near the SU-TM cleavage site and have established that uncleaved glycoprotein is unable either to be incorporated into virus particles efficiently or to induce membrane fusion. Additionally, the results suggest that cleavage of the envelope protein plays an important role in intracellular trafficking of protein via the cellular secretory pathway. Based on our results it was concluded that a positively charged residue located at either P2 or P4 along with the arginine at P1 is essential for cleavage.
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PMID:Effects of retroviral envelope-protein cleavage upon trafficking, incorporation, and membrane fusion. 2059 59

PCSK9 (Proprotein convertase Subtilisin/Kexin Type 9), an important regulator of lipid metabolism, has been shown to play a role in hepatocellular carcinoma by promoting metastasis. PCSK9 interferes with LDL metabolism and causes dyslipidemias in hematological malignancies particularly acute lymphoblastic leukemia. Nutraceuticals like berberine, curcumin and polydatin have been found effective in modulating PCSK9 expression by lowering LDL levels. Eugenol, a nutraceutical has shown a promising role in cancer due to its antioxidant and antihypercholesterolemic effects. In the present study, PCSK9 expression was measured in acute lymphoblastic leukemia (ALL) patients and was found to be significantly induced. Based on the results of expression analysis, a plausible hypothesis was made. Eugenol being an antioxidant will prevent oxidation of LDL. In the absence of ox-LDL, LOX1 scavenger receptor, which regulates PCSK9 expression, will not be activated. As the circulating LDL is reduced, it will no longer be able to support leukemia cell growth. The hypothesis was validated by an in silico and in vitro study. Molecular docking revealed hydrophobic interactions between ligand eugenol and macromolecules PCSK9 and LOX1. Expression of both PCSK9 and LOX1 were significantly reduced by eugenol in Jurkat cells. To conclude, PCSK9 could therapeutically be targeted by eugenol in leukemia cells.
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PMID:Could PCSK9 be a new therapeutic target of Eugenol? In vitro and in silico evaluation of hypothesis. 3181 13