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

Sequence analysis of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat (LTR) does not reveal a polyadenylation consensus sequence, AAUAAA, close to the polyadenylation site at the 3' end of the viral RNA. Using site-directed mutagenesis, we demonstrated that two cis-acting signals are required for efficient RNA processing in HTLV-I LTR: (i) a remote AAUAAA hexamer at a distance of 276 nucleotides upstream of the polyadenylation site, and (ii) the 20-nucleotide GU-rich sequence immediately downstream from the poly(A) site. It has been postulated that the folding of RNA into a secondary structure juxtaposes the AAUAAA sequence, in a noncontiguous manner, to within 14 nucleotides of the polyadenylation site. To test this hypothesis, we introduced deletions and point mutations within the U3 and R regions of the LTR. RNA 3'-end processing occurred efficiently at the authentic HTLV-I poly(A) site after deletion of the sequences predicted to form the secondary structure. Thus, the genetic analysis supports the hypothesis that folding of the HTLV-I RNA in the U3 and R regions juxtaposes the AAUAAA sequence and the poly(A) site to the correct functional distance. This unique arrangement of RNA-processing signals is also found in the related retroviruses HTLV-II and bovine leukemia virus.
 ...
PMID:An RNA secondary structure juxtaposes two remote genetic signals for human T-cell leukemia virus type I RNA 3'-end processing. 171 87

Human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type I (HTLV-I) were purified by sucrose density gradient centrifugation in the presence of 1 mM EDTA. Pelleted gradient fractions were analyzed for total protein, total Gag capsid protein, and total zinc. Zinc was found to copurify and concentrate with the virus particles. Through successive cycles of resuspending in buffer containing EDTA and repelleting, the zinc content remained constant at about 1.7 mol of zinc per mol of Gag protein. Proteins from purified virus (HIV-1 and HTLV-I) were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, blotted to polyvinylidene fluoride paper, and probed with 65ZnCl2. Viral nucleocapsid (NC) proteins (HIV-1 p7NC and HTLV-I p15NC) bound 65Zn2+. Other retroviruses, including simian immunodeficiency virus, equine infectious anemia virus, bovine leukemia virus, Moloney murine leukemia virus, mouse mammary tumor virus, and Mason-Pfizer monkey virus, were found to contain amounts of zinc per milligram of total protein similar to those found in HIV-1 and HTLV-I. Collectively, these data support the hypothesis that retroviral NC proteins function as zinc finger proteins in mature viruses.
 ...
PMID:Tightly bound zinc in human immunodeficiency virus type 1, human T-cell leukemia virus type I, and other retroviruses. 173 Nov 11

Bovine leukemia virus (BLV), like its closest relatives human T-cell leukemia virus-I and II, contain a 'px' gene, between the 'env' gene and the 3' long terminal repeat in its genome. A monoclonal antibody prepared against a synthetic oligopeptide whose sequence was deduced from highly conserved region of 'px' gene of BLV, was used to detect the presence of 'px' gene product in chronically BLV infected synchronised cells. By immunoperoxidase staining the 'px' gene product was detected maximum after 6-9 hr after synchronization in the nucleus of the cells which demonstrated the close interaction of it with viral DNA which is integrated with host cell genome.
 ...
PMID:Detection of px gene product of bovine leukemia virus in infected cells. 196 80

Bovine leukemia virus (BLV), like human T-cell leukemia viruses, Types I and II, contains three open reading frames at the 3' end of its genome. The longest open reading frame encodes a transactivator protein which is generated by a doubly-spliced mRNA. A series of co-transfection experiments, using proviral BLV pX expression plasmids under the control of the Moloney leukemia virus LTR and the indicator plasmid containing the assayable lac Z gene under the control of BLV LTR, revealed that both NIH3T3 cells and non-infected fetal lamb kidney cells are able to express an active transactivator protein.
 ...
PMID:Recombinants from a proviral bovine leukemia virus genome corresponding to the 3' region transactivate viral LTR in NIH3T3 and non-infected FLK cells. 196 62

A total of 216 cases of the thymic form of bovine leukosis were observed in Holstein calves in several departments of France over a period of 18 months. Almost all of these calves were sired by the same bull. The calves were negative for bovine leukemia virus-specific antibodies. Morphological studies, including light and electron microscopic cytology, and immunophenotyping were performed in 38 cases. The tumor cells exhibit membrane markers (T-cell antigens) at variable levels, which indicate that they are T-lymphoid derived. The cells are maintained at a very early stage of differentiation as indicated by TdT enzyme activity and the presence of MHC class II antigen.
Leukemia 1991 May
PMID:Epidemiological and pathological studies of a familial thymic lymphosarcoma in bovine species. 203 62

Bovine leukemia virus (BLV) was inoculated into one-day-old chickens. In a small part of inoculated chickens leukemia developed during observation period of one year. Out of 88 birds inoculated, only 4 developed histopathologically verified leukemia. The induced leukemia was characterized by enlarged liver and spleen. The organs were infiltrated with leukemic cells. The DNAs of body organs of inoculated chickens were analysed by Southern blot hybridization for the presence of BLV specific sequences. Out of 9 suspicious chickens tested in 6 birds the BLV was found to be integrated into host DNA either as a complete viral genome or as a part corresponding to its 3'-end. The leukemic cells were monoclonal as regard to the integration site of the BLV provirus. Neither the expression of BLV provirus in chicken leukemic cells nor the antibody response to BLV antigens in inoculated birds was detected. The rearrangements and amplification of erb-B and myb loci of protooncogenes in leukemic cells was detected. There were no changes in loci of following protooncogenes: myc, sis, fes, fps, erb A, src and yes. All obtained data taken together suggest that the BLV induced leukemia in chickens is caused by insertional mutagenesis.
 ...
PMID:Induction of leukemia in chicken by bovine leukemia virus due to insertional mutagenesis. 216 Feb 29

We tested 11 patients with multiple sclerosis for the presence of human T-cell leukemia virus type I (HTLV-I)- or type II (HTLV-II)-related sequences. DNA from blood mononuclear cells was analyzed by the polymerase chain reaction utilizing three different oligonucleotide primer pairs. Two of these primer pairs detect sequences shared between HTLV-I and HTLV-II in either p24, gag protein, or in p21, env transmembrane protein. The third primer pair was synthesized based on regions in the pol gene where amino acid sequences are conserved between HTLV-I, HTLV-II, and the related bovine leukemia virus. The multiple sclerosis samples were consistently negative while appropriate control samples were positive. We conclude that viruses related to HTLV-I, HTLV-II, or bovine leukemia virus are not present in the blood of patients with multiple sclerosis and, therefore, that HTLV-bovine leukemia virus-related viruses are not likely to be involved in the pathogenesis of multiple sclerosis.
 ...
PMID:Failure to detect human T-cell leukemia virus-related sequences in multiple sclerosis blood. 222 36

Rex protein of human T-cell leukemia virus type 1 (HTLV-1) induces cytoplasmic expression of unspliced gag/pol mRNA and singly spliced env mRNA and thus is essential for replication of the virus. This regulation requires a cis-acting rex-responsive element (RXE), located in the 3' region of the viral RNA. By external deletion, we have identified RXE composed of 205 nucleotides. The secondary structure of RXE was confirmed by studies on its susceptibility to nuclease digestions to consist of four stem-loops and a long stretch of stem structure. Substitution and deletion mutations revealed that two regions of the stem-loops and their secondary structures are essential for rex regulation. Similar secondary structures were found in the corresponding regions of HTLV-2, bovine leukemia virus and human immunodeficiency virus. Furthermore, a sequence of 11 nucleotides in the RXE was found to be conserved in the secondary structures of HTLV-1, HTLV-2, and bovine leukemia virus. These observations suggest that the secondary structure as well as the conserved sequence may be important in expression of unspliced RNA even with diverged sequences as observed in these viruses.
 ...
PMID:Secondary structure of the human T-cell leukemia virus type 1 rex-responsive element is essential for rex regulation of RNA processing and transport of unspliced RNAs. 233 18

Human T-cell leukemia and bovine leukemia viruses have a potential transforming gene, termed X. In addition to the major open reading frame known to encode a functional protein, the X gene harbors another short open reading frame which overlaps this major one. Both of these open reading frames are found on a single spliced X mRNA in a potentially functional form. Circumstantial evidence strongly suggests that they are both translated from the single X mRNA molecule, showing striking similarity to the translation mechanism of an adenovirus Elb gene mRNA. We note that the short open reading frame has the capability to encode a putative nuclear protein with structural features similar to those of an AIDS virus trans-acting protein.
 ...
PMID:Two distinct polypeptides may be translated from a single spliced mRNA of the X genes of human T-cell leukemia and bovine leukemia viruses. 241 30

We have cloned several prototypic members of the family of human endogenous retroviruslike elements having a histidine tRNA primer-binding site (RTVL-H) and have determined the nucleotide sequence of one of these clones (RTVL-H2). The RTVL-H2 sequence is 5,813 nucleotides long, with long terminal repeats of 450 nucleotides. Although this particular sequence contains no long open reading frames, computer searches have revealed several segments of amino acid homology with known retroviral gene products. In the gag region of RTVL-H2, there is a segment with significant homology to a region of the gag protein p30 of type C baboon endogenous virus. In the pol region of RTVL-H2, three segments similar to the Moloney leukemia virus (MLV) pol polyprotein were detected. These correspond to parts of the protease, reverse transcriptase, and endonuclease domains of the MLV pol gene. Interestingly, the last two pol domains are equidistant in RTVL-H2 and the type C murine retroviruslike DNA sequence (MuRRS), both having deletions of equal sizes relative to the MLV pol gene. One other segment similar to a retroviral gene product was identified in the RTVL-H2 gag region. This segment has 55 to 60% amino acid homology to a 50-amino-acid region of the gag nucleic acid-binding proteins encoded by human T-cell lymphotropic viruses types I and II and bovine leukemia virus. Thus, the RTVL-H2 genome harbors sequences related to evolutionarily distant retroviruses.
 ...
PMID:Human endogenous retroviruslike genome with type C pol sequences and gag sequences related to human T-cell lymphotropic viruses. 244 10


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>