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At least 19 recordsLinked to original sources
PubMed1985

Expression of the pX gene of HTLV-I: general splicing mechanism in the HTLV family.

Human T-cell leukemia virus type I (HTLV-I) is an etiological agent of adult T-cell leukemia. A viral gene pX encodes for p40X and it has been proposed that this protein trans-activates the viral long terminal repeat and possibly some cellular genes; this activation may be associated with T-cell transformation. The mechanism of pX gene expression and the primary structure of p40X are now reported. Two-step splicing generates the 2.1-kilobase pX mRNA; the initiator methionine for env becomes part of the pX protein. These splicing signals are conserved among all members of the HTLV family except for the acquired immune deficiency syndrome-associated viruses.

Animals↗
PubMed1985

Association of the pX gene product of human T-cell leukemia virus type-I with nucleus.

Human T-cell leukemia virus type I (HTLV-I) contains a unique gene pX coding for p40 chi, and this protein was suggested to activate the transcription from the LTR of HTLV. By a similar mechanism, this viral function might be involved in immortalization of T-cells and leukemogenesis in adult T-cell leukemia induced by HTLV-I. In this communication, a part of the p40 chi was found to be tightly associated with nuclei in infected cell lines by subcellular fractionation and immunofluorescence staining.

Cell Fractionation↗
PubMed1990

Detection of px gene product of bovine leukemia virus in infected cells.

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.

Amino Acid Sequence↗
PubMed1987

Immunoelectron microscopic localization of the pX gene products in human T-cell leukemia virus type 1-producing cells.

The location of the pX gene products in human T-cell leukemia virus type 1-producing cells, MT-2 and HUT 102, was studied by immunoelectron microscopy using the direct and indirect peroxidase-labeled antibody methods. Fab'-peroxidase conjugates were prepared for the direct method with a maleimide compound from antisera to the carboxy-terminal region of the pX gene products. Positive immunostaining in MT-2 cells was detected in the endoplasmic reticulum, the outer and inner leaflets of the nuclear membrane, and inside their cisternae, but not in the plasma membrane and viral particles. Staining in the nucleus was faint. On the other hand, positive immunostaining in HUT 102 cells was detected diffusely in the euchromatin regions of the nucleus but not in the nucleoli, nuclear envelope, and cellular membrane systems. The location of the positive immunostaining in the HUT 102 nuclei was reconfirmed by the reaction in isolated nuclei. On the basis of both the immunoelectron microscopic and immunoblotting analyses of the pX gene products, it is suggested that the Mr 40,000 to 42,000 protein (p40x) is localized mainly in the euchromatin regions of the nuclei of human T-cell leukemia virus type 1-producing cells, and the Mr 68,000 protein (p68x) is localized mainly in the nuclear envelope and the endoplasmic reticulum of MT-2 cells. p68x detected in MT-2 cells with the anti-p40x serum was deduced to be a protein consisting of p40x and a part of env gene products and to share epitopes in common with p40x.

Cell Line↗
PubMed1994

A spontaneous point mutation in the human T-cell leukemia virus type 1 pX gene leads to expression of a novel doubly spliced pX-mRNA that encodes a 25-kD, amino-terminal deleted rex protein.

Primary RNA transcripts of the human T-cell leukemia virus type 1 (HTLV-1) are processed into mature mRNA by a complex series of splicing events. In this paper, we report the finding of a novel doubly spliced pX mRNA in two out of eight HTLV-1-infected cell lines and in one out of 13 peripheral blood mononuclear cells from HTLV-1-infected individuals. The second splicing for this novel pX mRNA is different from that for the known doubly spliced pX mRNA. A novel acceptor site in this splicing was generated by a single point mutation (G to A) at nucleotide 7,337 of the pX gene. This mRNA contained a complete open reading frame that encodes an amino-terminal truncated p27rex protein with 189 amino acids. A new 25-kD protein was detected in the cell lines expressing the novel pX mRNA by an antibody against the carboxy-terminal peptide of p27rex and was termed p25rex. Although the function of p25rex is not clear, we clarified that p25rex is a cytoplasmic phosphoprotein and its function is different from the transcriptional regulator function of p27rex. The possibility that the mutated virus is replicable only in cells coinfected with the wild type HTLV-1 may explain why the incidence of the mutants observed here is low.

Amino Acid Sequence↗
PubMed1993

Detection of HTLV-I pX gene by polymerase chain reaction using newly designed primers.

Newly designed oligonucleotide primers, KI-7 and KI-8 for the human T cell lymphotropic virus type I (HTLV-I) pX gene were synthesized using an automated DNA synthesizer. Previously known HTLV-I-infected cell lines, MT-1 and MT-2, were used as positive controls and HTLV-I-uninfected cell lines, Molt-4, SBC-3, ABC-1, and EBC-1, as negative controls. Peripheral blood mononuclear cells from 17 patients with anti-HTLV-I antibody and 10 healthy individuals without anti-HTLV-I antibody were studied by polymerase chain reaction (PCR) with KI-7 and KI-8. All DNA samples from HTLV-I-infected cell lines and 17 patients with anti-HTLV-I antibodies showed positive signals of the HTLV-I pX gene. None of the DNA samples from HTLV-I-uninfected cell lines or 10 healthy individuals showed positive signals. When serially diluted DNA of MT-2 cells were amplified by 35 cycles of PCR, the detection limit of the pX gene by using the primer pairs was DNA from about 1.5 MT-2 cells. Specificity and detectable capacity of primer pairs, KI-7 and KI-8 were confirmed to be enough to use for the diagnosis of HTLV-I infection.

Base Sequence↗
PubMed1993

Detection of the pX gene of human T-lymphotropic virus type I in respiratory diseases with diffuse interstitial pulmonary shadows and lung cancer.

The presence of the HTLV-I gene in peripheral blood mononuclear cells was studied by polymerase chain reaction in 42 patients including 16 with lung cancer, 12 with diffuse panbronchiolitis (DPB), 11 with idiopathic interstitial pneumonia (IIP), and 3 with pneumoconiosis and hematological malignancy. Sequences equal to a part of the pX gene were found in 44% of the lung cancer cases, 50% of the DPB cases, 55% of the IIP cases, and 100% of the cases of pneumoconiosis and leukemia. In the lung cancer cases, detection of the pX gene was frequently associated with the existence of diffuse interstitial pulmonary shadows. The pX gene was detected in 100% of patients with anti-HTLV-I antibody, 50% of patients with HTLV-I-related reaction and 14% of patients who tested seronegative. It may be inferred from the results that respiratory diseases that produce diffuse interstitial pulmonary shadows are closely associated with HTLV-I infection and that the HTLV-I-related reaction to the immunofluorescent test might reflect the latent infection state of HTLV-I.

Base Sequence↗
PubMed1997

A wide spectrum of collagen vascular and autoimmune diseases in transgenic rats carrying the env-pX gene of human T lymphocyte virus type I.

To investigate the pathogenesis of human T lymphocyte virus type I (HTLV-I)- related diseases, the env-pX gene of HTLV-I was introduced into the germline of inbred Wistar-King-Aptekman-Hokudai rats. A wide spectrum of collagen vascular diseases was evident in the transgenic rats, including chronic destructive arthritis similar to rheumatoid arthritis, necrotizing arteritis mimicking polyarteritis nodosa, polymyositis, myocarditis, dermatitis, and chronic sialoadenitis and dacryoadenitis resembling Sjögren's syndrome in humans. Thymic atrophy with the depletion of CD4 and CD8 double-positive thymocytes was also observed. In these animals, a number of autoantibodies, including high titers of rheumatoid factor, were present in the serum. We propose that the HTLV-I env-pX gene region may play a pathogenetic role in the development of collagen vascular and autoimmune diseases associated with autoimmune phenomenon.

Animals↗
PubMed1989

Thymic atrophy characteristic in transgenic mice that harbor pX genes of human T-cell leukemia virus type I.

The human T-cell leukemia viruses (HTLV) are associated with T-cell malignancies in humans. The malignant transformation occurs after a long latency in some carriers, and its mechanism appears to be distinct from that of other classes of retroviruses which induce transformation through viral or cellular oncogenes. A widely postulated explanation is that the products of novel pX genes transactivate endogenous cellular genes which lead to tumor development in T cells. To directly examine the pathological effects of pX genes in vivo, we produced transgenic mice harboring the HTLV type I pX genes under several regulatory units: HTLV type I long terminal repeat, immunoglobulin enhancer-simian virus 40 promoter, and mouse mammary tumor virus long terminal repeat. Atrophy of the thymus was characteristic in these mice no matter which regulatory unit directed the expression of the genes.

Animals↗
PubMed1995

Cytokine-producing mammary carcinomas in transgenic rats carrying the pX gene of human T-lymphotropic virus type I.

In two lines of transgenic rats (pX rats) from WKAH and F344 strains and carrying the human T-lymphotropic virus type I pX gene, undifferentiated mammary carcinomas developed predominantly in females starting at about 5 months of age, and there was massive infiltration of granulocytes in the tumor tissue. The incidence of the tumor reached about 40% when the rats were 12 months old. mRNAs of both pX and host genes Gro and MIP-2, which are granulocyte chemoattractants of the interleukin 8 family, were highly expressed in the tumor tissue. Since expression and point mutation of several oncogenes and the antioncogene were not demonstrated, hitherto unidentified novel oncogenic pathways may be transactivated by the pX transgene in these pX rats.

Animals↗
PubMed1998

[Px gene of rice-field eels primed in situ labeling].

Peroxidase (Px) gene of rice-field eels (Monopterus albus) was successfully localized to the segments of two bivalents, 8q15-q26 and 11q32-q37 with digoxigenin labeled primed in situ labeling (PRINS) technique, which is utilized for localization of single copy gene of fish for the first time. Our results demonstrated the possibility of mapping genes in fish by the DNA probes of other species and PRINS technique.

Animals↗
PubMed1985

Determination of a splice acceptor site of pX gene in HTLV-I infected cells.

The splice acceptor site of pX gene of HTLV-I has been determined to be at base position 7301 using S1 nuclease protection analysis. This splice acceptor site is used in all HTLV-I immortalized T-cell clones studied despite variation in the abundance levels of pX mRNA. Our results confirmed the proposal by Haseltine et al. (W. A. Haseltine, J. Sodroski, R. Patarca, D. Briggs, D. Perkins, and F. Wong-Staal, Science (Washington, D. C. 225, 421-424 (1984); K. Shimotono, W. Wachsman, Y. Takahashi, D. W. Golde, M. Miwa, T. Sigimura, and I. S. Y. Chen, Proc. Natl. Acad. Sci. USA 81, 6657-6661 (1984)) that a pX protein with a molecular weight of at least 38,000 could be synthesized. Generation of a 2.0-kb pX mRNA may involve a double-splicing event.

Base Sequence↗
PubMed1996

The association of antibodies against human T cell lymphotropic virus type I (HTLV-I) pX gene mutant products with HTLV-I-associated myelopathy/tropical spastic paraparesis.

Antibodies specific for the products of the human T cell lymphotropic virus type I (HTLV-I) pX frame-shift mutants were studied by ELISA. The serum IgG antibodies to the synthetic peptide corresponding to one nucleotide insertion at position 7784 were significantly more common in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients than in HTLV-I carriers who had neither HAM/TSP nor adult T cell leukemia (39% vs. 5%). The seropositivities to the other synthetic peptides, which corresponded to the one nucleotide deletion at position 7475 and the internal deletion of nt 7754-7819 and nt 7853-7936, were rare. A genetic study confirmed the presence of the responsible mutation of the pX gene in peripheral blood mononuclear cells and central nervous system tissue from HTLV-I-infected subjects with and without HAM/TSP. These results suggest that HTLV-I pX frame-shift mutants are expressed in vivo in HTLV-I carriers; they also induce antibodies. especially in those with HAM/TSP.

Adult↗
PubMed1990

Recognition of human T cell leukemia virus type I (HTLV-I) gag and pX gene products by MHC-restricted cytotoxic T lymphocytes induced in rats against syngeneic HTLV-I-infected cells.

We established rat T cell lines expressing human T cell leukemia virus type I (HTLV-I) Ag from inbred strains of rats, WKA/H, DA, and F344, to study CTL response against the HTLV-I-infected cells. HTLV-I-specific Ag expressed in these rat cells were HTLV-I gag Ag, p19, p24, and p15, and pX Ag, p40tax and p27rex, but not env Ag, as determined by immunofluorescence and immunoblot assays. By immunization of rats with syngeneic HTLV-I-infected cells, CTL against syngeneic HTLV-I-infected cells and antibodies to HTLV-I Ag were generated in WKA/H and DA rats. The bulk CTL cultures from WKA/H and DA rats lysed specifically syngeneic SV40-transformed kidney cells infected with recombinant vaccinia viruses (RVV) expressing HTLV-I gag and pX Ag, but not those infected with RVV expressing HTLV-I env Ag or a control vaccinia virus. From WKA/H rat CTL cultures, four CTL clones reactive with syngeneic HTLV-I-infected cells were isolated, three of which were specific for p27rex/p21x, but the Ag recognized by the other CTL clone was not defined with any RVV used. These results indicate that HTLV-I gag and pX gene products are recognized by MHC-restricted rat CTL specific for syngeneic HTLV-I-infected cells.

Animals↗
PubMed1996

[Case of adult T-cell leukemia without antibodies for HTLV-I but with for pX gene region].

A 76-year-old woman had lymphocytosis with lymphocytes having convoluted or lobulated nuclei. These abnormal lymphocytes (leukemic cells) were positive for CD4, and some expressed IL-2R (CD25) and CD3 molecules, respectively. These morphologic and phenotypic features were compatible with adult T-cell leukemia, but serum antibodies to human T-cell lymphotropic virus type I (HTLV-I) were not detected by the particle aggregation method and an enzyme-linked immunosorbent assay. The polymerase chain reaction showed that the LTR, gag, pol, and env regions of HTLV-I proviral DNA had not been incorporated into the leukemic cells. Only the pX region was detected in these leukemic cells.

Aged↗
PubMed1986

A sequence homology between the pX genes of HTLV-I/II and the murine IL-3 gene.

Searching the protein sequence database for amino acid sequences homologous to the x-lor sequence in the pX region of human T-cell leukemia virus types I and II (HTLV-I/II), we found that there is a region of 38 amino acids where the murine interleukin 3 (IL-3) sequence has a 40% homology with the x-lor sequence. A statistical analysis shows that this homology is highly significant with a probability of 1.57 X 10(-10). The biological implication of this homology is discussed.

Amino Acid Sequence↗
PubMed1998

Promotion of early osteoclastogenesis and B lymphopoiesis in the bone marrow of transgenic rats with the env-pX gene of human T-cell lymphotropic virus type I.

Human T-cell lymphotropic virus type I (HTLV-I) is associated with various clinical disorders including adult T cell leukemia, myelopathy, arthropathy. Hypercalcemia resulting from osteoclast activation and a variety of hematopoietic abnormalities have been also observed in HTLV-I infected patients, however, precise mechanism about initial trigger(s) prior to presenting symptoms is still unknown. In this study, to assess effects of HTLV-I on hematopoiesis, we analysed characteristics of early hematopoietic precursors in HTLV-I env-pX transgenic rats. Progenitor cells for osteoclasts were significantly increased even in the marrow of asymptomatic env-pX rats. Progenitors for B cells were also highly enriched, while colony forming cells (CFC) elicited by GM-CSF(CFU-GM) and M-CSF(CFU-M) were comparable to normal littermates. Following arthritis in env-pX transgenic rats, osteoclastogenesis was further augmented and the CFCs were increased. Bone marrow cells carrying adjuvant-induced arthritis retained a constant number of progenitors for osteoclast and B lymphocytes, whereas the number of CFU-GM and CFU-M increased. These results indicate that the env-pX transgene affect early stages of osteoclast and B-cell lineages prior to developing diseases, in contrast, an increase of the CFCs was caused indirectly by arthritis. This study provides a novel standpoint for the mechanisms of pathogenesis by HTLV-I.

Animals↗