scholarly journals Cellular Transcription Factor ZASC1 Regulates Murine Leukemia Virus Transcription

2010 ◽  
Vol 84 (15) ◽  
pp. 7473-7483 ◽  
Author(s):  
James W. Bruce ◽  
Michael Hierl ◽  
John A. T. Young ◽  
Paul Ahlquist
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Cell Line ◽  
Binding Sites ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Cellular Transcription Factor ◽  
Cellular Transcription ◽  
Ltr Promoter ◽  
Murine Leukemia

ABSTRACT To identify cellular processes involved in retroviral infection, we employed a high-volume forward genetic screen of insertionally mutagenized somatic cells using a murine leukemia virus (MLV) vector. This approach identified a clonal cell line that exhibited approximately 10-fold reduced gene expression from MLV vectors following infection despite supporting normal levels of MLV reverse transcription and integration. The defect in this cell line was specific for the MLV long terminal repeat (LTR) promoter, as normal levels of reporter gene expression were obtained from both an internal cytomegalovirus (CMV) promoter contained within an LTR-defective MLV vector and LTR expression from an avian sarcoma and leukosis virus (ASLV) vector. Complementation and shRNA knockdown experiments demonstrated that the defective gene in these cells is ZASC1 (ZNF639), a transcription factor with strong links to cancer and inherited ataxias. We demonstrated that ZASC1 is a sequence-specific DNA binding protein with three closely related binding sites located within the MLV LTR promoter, but it does not bind to the ASLV promoter. Mutating these putative ZASC1 binding sites significantly reduced levels of MLV gene expression. While wild-type ZASC1 activated expression from the MLV promoter, a green fluorescent protein-ZASC1 fusion protein showed dominant-negative inhibition of MLV gene expression. These studies identify the cellular transcription factor ZASC1 as an activator of MLV gene expression and provide tools that should be useful in studying the links between ZASC1 and human diseases.

scholarly journals Increased Induction of Osteopetrosis, but Unaltered Lymphomagenicity, by Murine Leukemia Virus SL3-3 after Mutation of a Nuclear Factor 1 Site in the Enhancer

1999 ◽  
Vol 73 (12) ◽  
pp. 10406-10415 ◽  
Author(s):  
Steen Ethelberg ◽  
Barbara D. Tzschaschel ◽  
Arne Luz ◽  
Salvador J. Diaz-Cano ◽  
Finn Skou Pedersen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Binding Sites ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Transcription Factor Binding Sites ◽  
Nuclear Factor ◽  
Wild Type ◽  
Factor Binding ◽  
Nuclear Factor 1 ◽  
Murine Leukemia

ABSTRACT SL3-3 is a murine leukemia virus which is only weakly bone pathogenic but highly T-cell lymphomagenic. A major pathogenic determinant is the transcriptional enhancer comprising several transcription factor binding sites, among which are three identical sites for nuclear factor 1 (NF1). We have investigated the pathogenic properties of NF1 site enhancer mutants of SL3-3. Two different mutants carrying a 3-bp mutation either in all three NF1 sites or in the central site alone were constructed and assayed in inbred NMRI mice. The wild type and both mutants induced lymphomas in all mice, with a mean latency period of 9 weeks. However, there was a considerable difference in osteopetrosis induction. Wild-type SL3-3 induced osteopetrosis in 11% of the mice (2 of 19), and the triple NF1 site mutant induced osteopetrosis in none of the mice (0 of 19), whereas the single NF1 site mutant induced osteopetrosis in 56% (10 of 18) of the mice, as determined by X-ray analysis. A detailed histological examination of the femurs of the mice was carried out and found to support this diagnosis. Thus, the NF1 sites of SL3-3 are major determinants of osteopetrosis induction, without determining lymphomagenesis. This conclusion was further supported by evaluation of the bone pathogenicity of other SL3-3 enhancer variants, the lymphomagenicity of which had been examined previously. This evaluation furthermore strongly indicated that the core sites, a second group of transcription factor binding sites in the viral enhancer, are necessary for the osteopetrosis induction potential of SL3-3.

scholarly journals Expression of human adenosine deaminase from various strong promoters after gene transfer into human hematopoietic cell lines

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 876-881 ◽  
Author(s):  
RA Hock ◽  
AD Miller ◽  
WR Osborne
Keyword(s):  
Gene Expression ◽  
Cell Line ◽  
Adenosine Deaminase ◽  
Cell Lines ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
K562 Cells ◽  
Moloney Murine Leukemia Virus ◽  
Hematopoietic Cell Lines ◽  
Murine Leukemia

Adenosine deaminase (ADA) deficiency is associated with a fatal severe combined immunodeficiency. Because most patients do not have a suitable marrow donor, the introduction of a normal ADA gene into the patient's marrow cells is a potentially useful alternative therapy. To identify vectors that provide optimal gene expression in human hematopoietic cells, we investigated retroviral vectors containing the ADA gene under the transcriptional control of the promoter/enhancers of Moloney murine leukemia virus, the simian virus 40 early region, the cytomegalovirus immediate-early gene, the lymphotropic papovavirus, and the human beta- globin gene. ADA expression from these vectors was monitored in the ADA- human histiocytic lymphoma cell line DHL-9, and in the multipotential chronic myeloid leukemia cell line K562. ADA expression in infected K562 cells was also measured after induction of megakaryoblastic differentiation by phorbol ester, and after induction of erythroid differentiation by sodium n-butyrate or hemin. In these hematopoietic cell lines, the vectors that contained ADA controlled by either the Moloney murine leukemia virus promoter (LASN) or the cytomegalovirus promoter (LNCA) expressed ADA at much higher levels than the other vectors tested. Furthermore, in K562 cells infected with LASN and LNCA vectors, induction of terminal differentiation resulted in the same or higher level expression of ADA. These cell lines have permitted the evaluation of transduced gene expression in proliferating and differentiating hematopoietic cells that provide a model for bone marrow-targeted gene therapy.

scholarly journals Expression of human adenosine deaminase from various strong promoters after gene transfer into human hematopoietic cell lines

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 876-881 ◽  
Author(s):  
RA Hock ◽  
AD Miller ◽  
WR Osborne
Keyword(s):  
Gene Expression ◽  
Cell Line ◽  
Adenosine Deaminase ◽  
Cell Lines ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
K562 Cells ◽  
Moloney Murine Leukemia Virus ◽  
Hematopoietic Cell Lines ◽  
Murine Leukemia

Abstract Adenosine deaminase (ADA) deficiency is associated with a fatal severe combined immunodeficiency. Because most patients do not have a suitable marrow donor, the introduction of a normal ADA gene into the patient's marrow cells is a potentially useful alternative therapy. To identify vectors that provide optimal gene expression in human hematopoietic cells, we investigated retroviral vectors containing the ADA gene under the transcriptional control of the promoter/enhancers of Moloney murine leukemia virus, the simian virus 40 early region, the cytomegalovirus immediate-early gene, the lymphotropic papovavirus, and the human beta- globin gene. ADA expression from these vectors was monitored in the ADA- human histiocytic lymphoma cell line DHL-9, and in the multipotential chronic myeloid leukemia cell line K562. ADA expression in infected K562 cells was also measured after induction of megakaryoblastic differentiation by phorbol ester, and after induction of erythroid differentiation by sodium n-butyrate or hemin. In these hematopoietic cell lines, the vectors that contained ADA controlled by either the Moloney murine leukemia virus promoter (LASN) or the cytomegalovirus promoter (LNCA) expressed ADA at much higher levels than the other vectors tested. Furthermore, in K562 cells infected with LASN and LNCA vectors, induction of terminal differentiation resulted in the same or higher level expression of ADA. These cell lines have permitted the evaluation of transduced gene expression in proliferating and differentiating hematopoietic cells that provide a model for bone marrow-targeted gene therapy.

scholarly journals Mutated primer binding sites interacting with different tRNAs allow efficient murine leukemia virus replication.

1993 ◽  
Vol 67 (12) ◽  
pp. 7125-7130 ◽  
Author(s):  
A H Lund ◽  
M Duch ◽  
J Lovmand ◽  
P Jørgensen ◽  
F S Pedersen
Keyword(s):  
Virus Replication ◽  
Binding Sites ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Murine Leukemia

scholarly journals Murine Leukemia Virus P50 Protein Counteracts APOBEC3 by Blocking Its Packaging

2020 ◽  
Vol 94 (18) ◽  
Author(s):  
Wenming Zhao ◽  
Charbel Akkawi ◽  
Marylène Mougel ◽  
Susan R. Ross
Keyword(s):  
Cell Line ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Stable Cell Line ◽  
Host Restriction ◽  
C Terminus ◽  
Alternatively Spliced ◽  
Apobec3 Proteins ◽  
Murine Leukemia

ABSTRACT Apolipoprotein B editing enzyme, catalytic polypeptide 3 (APOBEC3) family members are cytidine deaminases that play important roles in intrinsic responses to retrovirus infection. Complex retroviruses like human immunodeficiency virus type 1 (HIV-1) encode the viral infectivity factor (Vif) protein to counteract APOBEC3 proteins. Vif induces degradation of APOBEC3G and other APOBEC3 proteins and thereby prevents their packaging into virions. It is not known if murine leukemia virus (MLV) encodes a Vif-like protein. Here, we show that the MLV P50 protein, produced from an alternatively spliced gag RNA, interacts with the C terminus of mouse APOBEC3 and prevents its packaging without causing its degradation. By infecting APOBEC3 knockout (KO) and wild-type (WT) mice with Friend or Moloney MLV P50-deficient viruses, we found that APOBEC3 restricts the mutant viruses more than WT viruses in vivo. Replication of P50-mutant viruses in an APOBEC3-expressing stable cell line was also much slower than that of WT viruses, and overexpressing P50 in this cell line enhanced mutant virus replication. Thus, MLV encodes a protein, P50, that overcomes APOBEC3 restriction by preventing its packaging into virions. IMPORTANCE MLV has existed in mice for at least a million years, in spite of the existence of host restriction factors that block infection. Although MLV is considered a simple retrovirus compared to lentiviruses, it does encode proteins generated from alternatively spliced RNAs. Here, we show that P50, generated from an alternatively spliced RNA encoded in gag, counteracts APOBEC3 by blocking its packaging. MLV also encodes a protein, glycoGag, that increases capsid stability and limits APOBEC3 access to the reverse transcription complex (RTC). Thus, MLV has evolved multiple means of preventing APOBEC3 from blocking infection, explaining its survival as an infectious pathogen in mice.

scholarly journals Evidence that Ecotropic Murine Leukemia Virus Contamination in TZM-bl Cells Does Not Affect the Outcome of Neutralizing Antibody Assays with Human Immunodeficiency Virus Type 1

2009 ◽  
Vol 83 (16) ◽  
pp. 8289-8292 ◽  
Author(s):  
Emily J. Platt ◽  
Miroslawa Bilska ◽  
Susan L. Kozak ◽  
David Kabat ◽  
David C. Montefiori
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Line ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Murine Leukemia

ABSTRACT The TZM-bl cell line that is commonly used to assess neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) was recently reported to be contaminated with an ecotropic murine leukemia virus (MLV) (Y. Takeuchi, M. O. McClure, and M. Pizzato, J. Virol. 82:12585-12588, 2008), raising questions about the validity of results obtained with this cell line. Here we confirm this observation and show that HIV-1 neutralization assays performed with a variety of serologic reagents in a similar cell line that does not harbor MLV yield results that are equivalent to those obtained in TZM-bl cells. We conclude that MLV contamination has no measurable effect on HIV-1 neutralization when TZM-bl cells are used as targets for infection.

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