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W Wachsman

Publications and source records attributed to W Wachsman.

At least 37 records · Page 2Linked to original sources
PubMed1988

Characterization of the human granulocyte-macrophage colony-stimulating factor promoter region by genetic analysis: correlation with DNase I footprinting.

T-cell activation induces expression of the hematopoietic growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF). To define the molecular events involved in the induction of GM-CSF gene expression more clearly, we prepared and analyzed deletion mutants of GM-CSF promoter recombinant constructs. The results localized inducible expression to a 90-base-pair region (-53 to +37) which is active in uninfected and human T-cell leukemia virus-infected T-cell lines but not in resting or mitogen-stimulated B cells. DNase I footprinting experiments revealed protection of sequences contained within this region, including a repeated nucleotide sequence, CATT(A/T), which could serve as a core recognition sequence for a cellular transcription factor. Upstream of these GM-CSF promoter sequences is a 15-base-pair region (-193 to -179) which has negative regulatory activity in human T-cell leukemia virus-infected T cells. These studies revealed a complex pattern of regulation of GM-CSF expression in T cells; positive and negative regulatory sequences may play critical roles in controlling the expression of this potent granulopoietin in the bone marrow microenvironment and in localized inflammatory responses.

B-Lymphocytes↗
PubMed1988

Integrated human T-cell leukemia virus II genome in CD8 + T cells from a patient with "atypical" hairy cell leukemia: evidence for distinct T and B cell lymphoproliferative disorders.

We previously reported isolation of human T-cell leukemia virus II (HTLV-II) from a second patient (N.R.A.) with atypical hairy cell leukemia. Follow-up analysis of the characteristics of the patient's HTLV-II infection over a 2-year period has revealed that the patient had two coexistant lymphoproliferative disorders. Oligoclonally integrated HTLV-II was detected in DNA extracted from the patient's peripheral blood mononuclear cells on separate occasions greater than 1 year apart, similar to integration of HTLV-I seen in adult T cell leukemia/lymphoma. Although integrated provirus was readily detected, no HTLV-II viral RNA expression was seen in fresh peripheral blood lymphoid cells. Although the patient's peripheral blood consistently contained a majority of atypical lymphoid cells with a T cell antigenic phenotype, he ultimately developed extensive pleural, hepatic and soft tissue infiltration with malignant Tac+, tartrate-resistant, acid phosphatase-positive (TRAP+) B cells of clonal origin. To further characterize the role of HTLV-II, the patient's peripheral blood mononuclear cells were fractionated into four enriched subpopulations at autopsy. Oligoclonally integrated HTLV-II was detected in DNA from a T cell-enriched fraction and a CD8+ T cell-enriched fraction, but not in a CD4+ T cell-enriched fraction, a non-T cell fraction, or in B cells obtained from the malignant pleural effusion. We conclude that the patient harbored two distinct lymphoproliferative disorders, a TRAP+, Tac+ B cell malignancy consistent with hairy cell leukemia that did not contain HTLV-II and a Tac-, CD8+ lymphoproliferative syndrome with oligoclonally integrated HTLV-II.

Aged↗
PubMed1987

HTLV x gene mutants exhibit novel transcriptional regulatory phenotypes.

The human T-cell leukemia viruses, HTLV-I and HTLV-II, contain a gene, termed x, with transcriptional regulatory function. The properties of the x proteins were analyzed by constructing mutant genes containing site-directed deletions and point mutations. The results demonstrate that the amino terminal 17 amino acids of the x protein constitute part of a functional domain that is critical for the transcriptional activating properties of the protein. Within this region, substitution of a leucine residue for a proline residue results in major changes in the trans-activation phenotype of the protein. The mutant HTLV-II x protein, though incapable of activating the HTLV-II long terminal repeat, will block trans-activation of the HTLV-II long terminal repeat by the wild-type protein. The altered phenotype of this mutant suggests a potential negative regulatory function of the x protein.

Deltaretrovirus↗
PubMed1986

Comparison of the trans-activation capabilities of the human T-cell leukemia virus type I and II chi proteins.

The mechanism of cellular transformation by the human T-cell leukemia viruses (HTLVs) is thought to involve a novel retrovirus gene known as chi. The chi gene is essential for HTLV replication and acts by enhancing transcription from the viral long terminal repeat. By using the HTLV type I and II chi gene-coding regions inserted into a highly efficient expression vector, we directly compared the efficiencies of the two chi proteins to trans activate the HTLV type I and II long terminal repeats. We demonstrate that the two chi proteins have different patterns of trans activation. The patterns were highly reproducible in all mammalian cells tested. A different pattern of activation was observed in avian cells. These results suggest that the mechanism of trans activation involves specific cellular factors that are highly conserved throughout mammalian species but different in avian cells. Understanding the mechanism of trans activation by the chi gene product may provide insights into mechanisms of cellular transformation by HTLV.

Acetyltransferases↗
PubMed1986

The role of the x gene in HTLV associated malignancy.

Future studies on mechanisms of human T-cell leukaemia virus (HTLV) induced T-cell malignancy will focus on the role of the chi gene. This unique gene is found only in HTLV and the related bovine leukaemia virus, and is thought to be the transforming gene of these viruses, though direct proof of that role is still lacking. Recent studies indicate that the protein encoded by this gene has transcriptional regulatory properties similar to those of transcriptional regulatory proteins of other DNA viruses. An understanding of the mechanism of action of the HTLV chi protein will provide further insights into the hypothesis that cellular transformation and, ultimately, leukaemogenesis by HTLV is a result of aberrant transcription in T cells induced by the chi protein.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The x gene is essential for HTLV replication.

The human T-cell leukemia viruses (HTLV) are associated with T-cell malignancies in man and will transform normal human T cells in vitro. The mechanism of malignant transformation by HTLV is unknown but appears to be distinct from that of other classes of retroviruses, which induce malignant transformation through viral or cellular oncogenes. Recently a new gene, termed x, was identified in HTLV. This gene has been hypothesized to be the transforming gene of HTLV because of its conservation within the HTLV class of retroviruses. By in vitro mutagenesis of the HTLV-II x gene, it is now demonstrated that the presence of a functional x gene product is necessary for efficient HTLV transcription. Therefore, these studies provide direct evidence for an important function of the x gene in HTLV replication. The functional analogies between the x gene and transcriptional regulatory genes of some DNA viruses suggest that these viruses share similar mechanisms for cellular transformation.

Base Sequence↗
PubMed1985

HTLV x-gene product: requirement for the env methionine initiation codon.

The human T-cell leukemia viruses (HTLV) are replication-competent retroviruses whose genomes contain gag, pol, and env genes as well as a fourth gene, termed x, which is believed to be the transforming gene of HTLV. The product of the x gene is now shown to be encoded by a 2.1-kilobase messenger RNA derived by splicing of at least two introns. By means of S1 nuclease mapping of this RNA and nucleic acid sequence analysis of a complementary DNA clone, the complete primary structure of the x-gene product has been determined. It is encoded by sequences containing the env initiation codon and one nucleotide of the next codon spliced to the major open reading frame of the HTLV-I and HTLV-II x gene.

Amino Acid Sequence↗
PubMed1985

Human T-cell leukemia virus x gene.

The human T-cell leukemia virus (HTLV) types I and II are associated with specific hematological cancers. These viruses rapidly transform normal T-lymphocytes in vitro. The mechanism of HTLV-induced leukemogenesis is unknown. Structural analysis of HTLV-I and HTLV-II has revealed sequences of unknown function, termed X, at the 3' end of the proviral genome. The distal two-thirds of the X sequences are highly conserved between HTLV-I and HTLV-II. We have shown that these conserved X sequences contain a gene, termed x, that is expressed in both HTLV-I and HTLV-II by identifying a subgenomic X RNA as well as the proteins encoded by these messages. The function of this unique x gene is unknown; however, its conservation and expression suggest that it may play a role in HTLV replication and in HTLV-induced leukemogenesis.

Cell Line↗
PubMed1984

Expression of the 3' terminal region of human T-cell leukemia viruses.

Human T-cell leukemia viruses (HTLV) are closely associated with some human T-cell leukemias and lymphomas. A unique 3' region of the HTLV genome is believed to be involved in HTLV-induced cellular transformation, although the function of this region has yet to be determined. A subgenomic messenger RNA transcribed from this region of HTLV has now been characterized. These results provide direct evidence for the expression of a novel gene in HTLV.

Base Sequence↗
PubMed1984

Nucleotide sequence of the 3' region of an infectious human T-cell leukemia virus type II genome.

The nucleic acid sequence of the 3' region of human T-cell leukemia virus type II (HTLV-II) proviral DNA was determined using a HTLV-II proviral clone that could be recovered as infectious, transforming virus. The sequence data indicate a region of unknown function of approximately equal to 1.6 kilobase pairs in the 3' region, analogous to the X region previously identified in human T-cell leukemia virus type I (HTLV-I). Three overlapping open reading frames are present in the X region of HTLV-II. One of these open reading frames, Xc, is most likely to encode a protein product, because it has greater predicted amino acid sequence homology (78%) with the X-IV region of HTLV-I and a greater percentage of its base differences with X-IV at the third nucleotide position of codons than do the other open reading frames. Sequences of the X-region that include the open reading frames are conserved in two deletion mutants of HTLV-II, which are associated with a subline of Mo cells with a decreased dependence on fetal bovine serum.

B-Lymphocytes↗
PubMed1984

Quinidine-induced neutropenia: report of a case with drug-dependent inhibition of granulocyte colony generation.

We describe a case of quinidine-induced agranulocytosis in which in vitro marrow culture studies suggested immune inhibition of committed human granulocyte-macrophage progenitors (CFU-GM). Autologous, but not allogeneic, inhibition of CFU-GM was seen with 'acute' serum from the patient in the presence of quinidine but not other drugs. Cytotoxic antibodies to mature granulocytes were not found. These studies provide a novel mechanism for drug-induced neutropenia and suggest that a battery of in vitro assays of progenitor and of mature granulocyte cytotoxicity might identify offending agents in suspected drug-induced neutropenias.

Agranulocytosis↗
PubMed1984

Hairy cell leukemia and human T cell leukemia virus.

HCL is a lymphoproliferative disorder, primarily of B cells. T cell variant HCL is a rare clinical entity, which has a clinical picture similar to that of the common B cell HCL disease. HTLV-II has been isolated from a case of T cell variant HCL. This subtype of HTLV-II-associated disease is indolent in character in comparison to the very aggressive HTLV-I-associated disease. Investigation of the biology and molecular genetics of HTLV is in progress. It is hoped that better understanding of HTLV and the comparative differences between HTLV-I and HTLV-II will provide specific insights into the mechanisms of human leukemogenesis.

Adult↗
PubMed1984

The comparative molecular biology of HTLV-I and HTLV-II.

The human T-cell leukemia viruses (HTLV) I and II, have been implicated in naturally occurring T-cell malignancies in man. We are engaged in ongoing comparative studies of HTLV-I and HTLV-II in our laboratory. We have isolated a replication-competent clone of HTLV-II, as well as several defective HTLV-II proviruses from the Mo-T hairy-cell leukemia line. HTLV-II is able to transform normal T-lymphocytes, and can replicate in both T- and B-cell lines. We have devised a convenient system allowing direct transfection of the HTLV-II genome into a B-cell line, followed by selection of HTLV-infected cells. Transfection studies with HTLV-II indicate that the virus can replicate in lymphoid cells, but not in fibroblasts. Transfection of recombinant constructs demonstrates that the viral long terminal repeat (LTR) can function as a promoter in lymphoid cells, but not in fibroblasts, suggesting a role for the viral LTR in conferring target cell specificity. Structural similarities between the HTLV-I and HTLV-II LTRs, including the presence of similar repeated base sequences in the U3 region, may account for this LTR specificity. The X region of HTLV-II has been sequenced and compared to that of HTLV-I. We have identified an mRNA species encoded by the major open reading frames in the X region of HTLV-I and HTLV-II and have located the splice acceptor site. Using antisera generated to short peptide sequences encoded by X, we have identified specific X-encoded viral proteins in HTLV infected cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Transformation, Neoplastic↗
PubMed1982

Protein A adsorption of acute myelogenous leukemia serum induces in vitro blast lysis.

We studied cytotoxic activity of acute myelogenous leukemia (AML) sera for AML blasts before and after immunoadsorption with Staphylococcus aureus, Cowan I (SAC), which contains protein A. We found in vitro that incubation with treated AML sera reduced viability to 42.7% of control (p less than 0.01) for autologous and 21.0% of control (p less than 0.01) for allogeneic blasts. Normal peripheral blood cells were not killed by treated AML sera. Wood 46 strain of Staphylococcus aureus, which does not contain protein A, did not significantly reduce AML blast viability (94.8%, p greater than 0.4), while Sepharose-bound protein A reduced viability to 63.8% (p less than 0.01). Cytotoxicity does not appear to be complement-mediated, byt cytotoxic activity is trypsin-sensitive and is contained in the immunoglobulin fraction. This model for study of the tumoricidal action of protein A adsorption should be useful for predicting utility of plasma adsorption as a therapeutic adjunct in the future.

Cytotoxicity, Immunologic↗
PubMed1980

Conformational changes in deoxyribonucleic acid during transcription.

Circular dichroism (CD) was used to examine changes in secondary structure of calf thymus DNA during in vitro transcription. Formation of a binary complex between DNA and RNA polymerase (nucleoside triphosphate:nucleotidyltransferase, EC 2.7.7.6) did not alter the CD spectrum of the DNA. Alterations in ellipticity in the spectral region between 245 and 300 nm occurred during synthesis of RNA. This change was consistent with a B- to A-like form transition in polynucleotide conformation. The increment of ellipticity consisted of two separate compounds; component I was insensitive to treatment with pancreatic ribonuclease whereas component II was a ribonuclease labile fraction. Cleavage by restriction endonucleases did not produce or significantly alter the ellipticity of transcription. In contrast, between 50% and 60% of the component I ellipticity was sensitive to pancreatic DNase I. The data indicate that component I is a property of DNA and suggest that the alteration in secondary conformation which affects this component extends cooperatively beyond the DNase I insensitive DNA-RNA polymerase complexes.

Animals↗